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`Feinmetall Exhibit 2020
`FormFactor, Inc. v. Feinmetall, GmbH
`IPR2019-00082
`
`Page 1 of 18
`
`

`

`
`US. Patent
`
`
`
`
`Nov. 7,2000
`
`
`
`
`
`Sheet 1 0f 10
`
`6,144,212
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`
`
`
`FIG. 1
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`
`FIG. 28
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`Page 2 of 18
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`Page 2 of 18
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`

`

`
`US. Patent
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`
`
`
`Nov. 7,2000
`
`
`
`
`Sheet 2 0f 10
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`6,144,212
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`
`
`
`FIG. 3
`
`F
`
`
`
`DISPLACEMENT
`
`
`
`
`FIG. 4
`
`
`5a 5b
`
`
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`5a 5b
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`
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`5
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`
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`‘1'“!-
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`
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`Page 30f 18
`
`Page 3 of 18
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`

`

`
`US. Patent
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`
`
`
`Nov. 7,2000
`
`
`
`
`Sheet 3 0f 10
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`6,144,212
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`
`
`
`FIG. 6
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`Page 40f 18
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`Page 4 of 18
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`

`

`
`US. Patent
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`
`
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`Nov. 7, 2000
`
`
`
`
`Sheet 4 0f 10
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`6,144,212
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`
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`FIG. 9
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`FIG. 10
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` \\\\\“\‘ s\\\\\\“
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`FIG. 11
`
`4d
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`4d
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`5
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`
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`' {II/II'—
`
`4b '
`
`\‘\\““‘
`.‘\‘\\“‘
`
`\
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`4b
`
`\
`
`VIII/l,
`\“
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`
`
`Page 50f 18
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`Page 5 of 18
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`

`

`
`US. Patent
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`
`
`
`Nov. 7,2000
`
`
`
`
`Sheet 5 0f 10
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`6,144,212
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`
`
`
`FIG. 12
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`FIG. 13
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`
`FIG. 14
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`Page 60f 18
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`Page 6 of 18
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`

`

`
`US. Patent
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`
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`Nov. 7,2000
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`
`
`
`Sheet 6 0f 10
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`6,144,212
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`FIG. 15
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`21
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`FIG. 16
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`21
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`7
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`\\\\\\\\\\\\\\\\\\\\VX\\\\\
`'IIIIIIIEEm:Will/[11111-‘ 20
`—
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`/ 4c
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`4
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`6
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`FIG. 17
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`
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`23
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`20\
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`- ///////\
`‘\\\Z\
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`//////1
`///////////Il/l/lfl/l//////////
`
`
`
`4d
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`Page 7 of 18
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`Page 7 of 18
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`

`

`
`US. Patent
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`Nov. 7, 2000
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`Sheet 7 0f 10
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`6,144,212
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`FIG. 18
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`FIG. 19
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`Page 80f 18
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`Page 8 of 18
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`

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`US. Patent
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`Nov. 7,2000
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`Sheet 8 0f 10
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`6,144,212
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`FIG. 21
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`\\\\\\\\‘
` ‘\\\\\\\c
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`FIG. 23
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`4d
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`n\\\\\\\‘——\\\
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`VII/1
`E‘—
`
`_
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`58.
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`Page 90f 18
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`Page 9 of 18
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`

`

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`US. Patent
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`Nov. 7, 2000
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`Sheet 9 0f 10
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`6,144,212
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`FIG. 24 PRIOR ART
`
`
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`”III/II/IllIII/IIIIIII’I”_ 'llI’III/IIII/III/II/I/II/IA
`RW’WJ’
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`
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`FIG. 25 PRIOR ART
`
`
`
`DISPLACEMENT
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`FIG. 26 PRIOR ART
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`Page 100f18
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`Page 10 of 18
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`

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`US. Patent
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`Nov. 7,2000
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`Sheet 10 0f 10
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`6,144,212
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`FIG. 27 PRIORART
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`FIG. 28 PRIOR ART
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`
` l—argy/arvy/
`V/////;2’nlay/y.
`[£5]
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`V
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`Page11of18
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`Page 11 of 18
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`

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`6,144,212
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`
`1
`VERTICAL NEEDLE TYPE PROBE CARD,
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`
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`
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`METHOD OF MANUFACTURING THEREOF,
`
`
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`METHOD OF REPLACING DEFECTIVE
`
`
`
`PROBE NEEDLE AND TEST METHOD OF
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`WAFER USING THE PROBE CARD
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`
`
`BACKGROUND OF THE INVENTION
`
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`1. Field of the Invention
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`The present invention relates generally to a vertical needle
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`type probe card and more particularly to an improved
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`vertical needle type probe card which can be manufactured
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`low cost and allow a shorter test
`time. The present
`at
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`invention also relates to a method of manufacturing such a
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`vertical needle type probe card. Further, the present inven-
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`tion relates to a method of replacing a defective probe needle
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`of the vertical needle type probe card. The present invention
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`also relates to a test method of a wafer using the probe card.
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`2. Description of the Background Art
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`In manufacturing an IC, an LSI or the like, a plurality of
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`wafer chips are generally produced on one board. Before
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`these wafer chips are cut on a chip basis, a wafer test is
`carried out to check whether an individual chip is defective
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`or not. In such a wafer test, a device called a prober is
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`usually connected to a probe card, and a probe needle of the
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`probe card comes into contact with a prescribed electrode
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`(pad) of a semiconductor chip. After the probe needle comes
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`into contact with the semiconductor chip, constant pressure
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`(called needle pressure) is applied between the probe needle
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`and the pad (this operation is called an overdrive). As a result
`of the overdrive, the probe needle is slid and moved on the
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`pad surface, removing aluminum oxide of the pad surface.
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`Thus, aluminum under aluminum oxide is electrically con-
`nected to the probe needle.
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`FIG. 24 is a cross sectional view of a probe card using a
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`conventional cantilever type probe needle disclosed in Japa-
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`nese Utility Model Laying-Open No. 57-146340. The probe
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`card includes one printed wiring board 1 (hereinafter
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`referred to as a board). An opening 2 is provided in the
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`center of board 1. Aplurality of probe needles 3 are radially
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`provided at the lower surface of board 1 so that their tips
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`reach prescribed positions in opening 2. The base of probe
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`needle 3 and a contact portion for connecting a connector
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`(not shown) provided at the end of board 1 are connected by
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`a printed wiring or wire.
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`FIG. 25 shows the relationship between the displacement
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`of the cantilever type probe needle and a force (F). In this
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`specification,
`the probe needle displacement denotes the
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`height of the tip of probe needle 3 from the lower surface of
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`board 1, as shown in FIG. 26. In this specification, the force
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`(F) denotes needle pressure (F) which is applied to probe
`needle 3 in its height direction at the time of the overdrive.
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`Referring to FIG. 25, a linear relationship is formed by the
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`displacement of the probe needle and the force. In general,
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`the overdrive of approximately 100 um applies the needle
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`pressure of approximately a few grams (for example, 7 g) to
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`probe needle 3. Thus,
`the pad and probe needle 3 are
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`electrically connected to perform the wafer test.
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`The relative positions of probe needle 3 and the pad are
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`essential in each of longitudinal, lateral and height direc-
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`tions. For each direction, the precision of approximately :10
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`pm is required. A high density IC which will be developed
`from now on should demand a much stricter precision. At
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`present, the relative positions of the probe needle and the
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`pad are adjusted by hand. In this case, it is difficult to adjust
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`the height of the probe needle (distance of the tip of the
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`probe needle from the lower surface of the board).
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`10
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`15
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`20
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`25
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`Page 12 of18
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`2
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`In order to test a memory IC, a method called a simulta-
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`neous test
`is usually employed to simultaneously test a
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`plurality of memory IC chips on a wafer. In the simultaneous
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`test, probe needles usually come into contact with a total of
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`2x8=16 pads. In short, referring to FIG. 24, one row of the
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`cantilever type probe needles comes into contact with 1
`row><8 ICs and another row of the probe needles comes into
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`contact with 1 row><8 ICs, with a total of 2x8 memory IC
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`chips tested simultaneously by the probe needles on the both
`sides.
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`It is assumed here that one wafer has such number and
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`arrangement of IC chips that the tests of all the IC chips are
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`completed after 20 times of the 2x8 simultaneous tests. In
`this case, the numbers of the 4x4 simultaneous tests and the
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`4x8 simultaneous tests are smaller than the 2x8 simulta-
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`neous tests, as described below.
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`In the case of the 2x8 simultaneous test, 20 times/wafer
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`in the case of the 4x4 simultaneous test, 15 times/wafer
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`(—25%)
`in the case of the 4x8 simultaneous test, 10 times/wafer
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`(—50%)
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`The more the number of chips to be tested simultaneously
`as in the case of 4x8=32 chips, the smaller the number of the
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`test times. For the same number of the simultaneous tests,
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`the test numbers are smaller in the 4x4 test than in the 2x8
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`test. It can be understood considering the arrangement of a
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`plurality of memory IC chips on one wafer.
`The smaller number of the test times means a shorter test
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`time per wafer. The data above indicates that reduction of the
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`test time by 25% or 50% is possible simply through modi-
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`fication of the probe card structure.
`With the reduction of the test time, the time for the test
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`process is shortened and therefore quick delivery of products
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`becomes possible. Further, production is increased by 25%
`or 50% with the same number of the testers. Therefore, it is
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`a great task for those of who carry out the wafer tests to
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`increase the number of chips to be tested simultaneously by
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`a probe card.
`Both of the 2x8 structure and the 4x4 structure which
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`allow the simultaneous test of 16 chips do not require
`modification of the tester. Therefore, the 4x4 structure which
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`allows a shorter test time should have been realized by now.
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`However,
`the 4x4 structure in which two stages of the
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`cantilever type probe needles are placed on both sides as
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`shown in FIG. 27 has not been realized. Although this type
`of the 4x4 structure can be manufactured in principle,
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`maintenance such as adjustment of longitudinal, lateral and
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`height positions and repair after each test is very compli-
`cated and difficult, resulting in the maintenance cost per
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`needle several times higher.
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`For example, the difficulty of adjustment would be readily
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`understood if the precision of the probe needle is indicated
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`by numerical values. The probe needle specification is as
`follows.
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`tip diameter of the probe needle: about 30 Mmq)
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`pitch of the probe needle: about 100 um
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`number of the probe needle: about 300 pieces/row
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`positional precision of the probe needle: about :10 pm
`In short, in the case of the 4x4 simultaneous test, there are
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`about 300 needles in one row. Let us consider the two inner
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`rows of the probe needles which are longer with reference to
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`FIG. 27.
`In this case,
`it
`is very difficult
`to adjust
`the
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`longitudinal, lateral and height positions of the probe needle
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`so that the positional precision of the tip of the probe needle
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`is always about :10 pm. In this present situation, therefore,
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`the 2x8 simultaneous test method is employed by the probe
`card which has only the two outer rows.
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`Page 12 of 18
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`6,144,212
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`In recent years, the degree of integration has greatly be
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`improved from 16 M to 64 M and to 256 M especially in a
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`DRAM memory IC, and it causes a longer test time which
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`is an obstacle in the IC production line. Therefore, reduction
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`in the test time is immediately required.
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`The structures such as 4x4, 4x8 and n (at least 4)><m
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`which are effective in reducing the test time have been
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`studied for practical use by introducing a probe card
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`(hereinafter referred to as a vertical needle type probe card)
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`which uses a probe needle called a vertical needle.
`FIG. 28 is a cross sectional view of a conventional vertical
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`needle type probe card described in NIKKEI
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`MICRODEVICES, September 1996, pp. 101—106. Referring
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`to FIG. 28, a pin 4 is arranged in a vertical direction through
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`a hole in a guide plate 6. The end of pin 4 is arranged in an
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`arbitrary manner. A wafer is vertically moved from below
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`toward above to contact pin 4. Since pin 4 functions as a
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`spring, a load is applied to the pin end when the pin is
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`retrieved. Since the conventional vertical needle type probe
`card has been described to this extent, its structure and the
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`method of manufacturing thereof are not well known.
`SUMMARY OF THE INVENTION
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`Therefore, an object of the present invention is to provide
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`a vertical needle type probe card which facilitates provision
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`of the structures such as 4x4, 4x8 and n (at least 4)><m.
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`Another object of the present invention is to provide an
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`improved vertical needle type probe card which can be
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`manufactured easily and at low cost.
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`Yet another object of the present invention is to provide an
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`improved vertical needle type probe card which allows a
`shorter test time.
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`Yet another object of the present invention is to provide an
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`improved vertical needle type probe card which allows
`reduction in test cost.
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`Another object of the present invention is to provide a
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`vertical needle type probe card which allows cheap ICs to
`users.
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`Yet another object of the present invention is to provide a
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`method of manufacturing such a vertical needle type probe
`card.
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`A further object of the present invention is to provide a
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`method of replacing a defective probe needle of the vertical
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`needle type probe type.
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`A further object of the present invention is to provide a
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`test method of a wafer using the probe card.
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`A vertical needle type probe card according to a first
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`aspect of the present invention is adapted to transfer an
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`electric signal from an IC to a tester by bringing the lower
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`portion of a probe needle vertically in contact with an IC
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`pad. The vertical needle type probe card includes a probe
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`needle having upper and lower portions and an intermediate
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`portion connecting them. The upper portion of the probe
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`needle penetrates an upper guide plate. The upper guide
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`plate supports the upper portion of the probe needle. Alower
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`guide plate is provided under the upper guide plate. The
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`lower portion of the probe needle penetrates the lower guide
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`plate. The lower guide plate supports the lower portion of the
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`probe needle. A conductive rubber sheet is provided on the
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`upper guide plate. Aprinted wiring board is provided on the
`conductive rubber sheet. In the conductive rubber sheet, a
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`conductive path is provided which electrically connects the
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`upper portion of the probe needle to the printed wiring board
`so as to transfer the electric signal from the IC to the tester.
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`According to a vertical needle type probe card of a second
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`aspect, the intermediate portion of the probe needle is finer
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`40
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`Page 13 of18
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`4
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`than the upper and lower portions, and the upper portion of
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`the probe needle is bent into an L shape to have vertical and
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`horizontal portions.
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`According to a vertical needle type probe card of a third
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`aspect, the intermediate portion of the probe needle has a
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`rectangular sectional shape.
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`According to a vertical needle type probe card of a fourth
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`aspect, the probe needle is formed by bending a plate-like
`member.
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`According to a vertical needle type probe card of a fifth
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`aspect, the upper guide plate has a hole for passing the upper
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`portion of the probe needle therethrough, and a groove
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`provided at the surface of the plate to be connected to the
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`hole for fiXing the horizontal portion of the probe needle
`which is fit therein.
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`According to a vertical needle type probe card of a sixth
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`aspect, the upper and lower guide plates are spaced apart by
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`a prescribed distance to eXpose the intermediate portion of
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`the probe needle, and the upper and lower guide plates are
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`horizontally displaced to curve the intermediate portion of
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`the probe needle.
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`According to a vertical needle type probe card of a
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`seventh aspect, one end of the conductive path is in contact
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`with the surface of the horizontal portion of the probe
`needle.
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`According to a vertical needle type probe card of a eighth
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`aspect, the upper and lower guide plates are formed of the
`same material as a wafer on which an IC chip to be
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`wafer-tested is formed.
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`According to a vertical needle type probe card of a ninth
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`the upper and lower guide plates are formed of
`aspect,
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`mica-based ceramics having superior processability.
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`According to a method of manufacturing a vertical needle
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`type probe card of a tenth aspect, the lower portion of the
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`probe needle is vertically in contact with an IC pad, and an
`electric signal from the IC is transferred to a tester. First, a
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`probe needle is prepared which has upper and lower portions
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`and an intermediate portion connecting them, with its upper
`portion bent into an L shape to form vertical and horizontal
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`portions. Then, an upper guide plate is prepared which has
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`through hole for passing the probe needle
`a first
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`therethrough, and a groove formed at the surface so that the
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`vertical portion of the probe needle is fit in the groove. A
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`lower guide plate is prepared which has a second through
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`hole for passing the probe needle therethrough. The upper
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`guide plate is placed on the lower guide plate so that the first
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`and second through holes are aligned vertically. A probe
`needle is inserted into the first and second through holes
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`until the horizontal portion is fit in the groove. The upper and
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`lower guide plates are separated to eXpose the intermediate
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`portion of the probe needle. The upper and lower guide
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`plates are horizontally displaced to curve the intermediate
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`portion of the probe needle. A conductive rubber sheet is
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`formed on the upper guide plate. A printed wiring board is
`formed on the conductive rubber sheet. The conductive
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`rubber sheet is compressed by the upper guide plate and the
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`printed wiring board.
`In the conductive rubber sheet, a
`conductive path is formed which has one end connected to
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`the printed wiring board and the other end electrically
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`connected to the horizontal portion of the probe needle.
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`The invention according to an eleventh aspect relates to a
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`method of replacing a defective probe needle with a new
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`probe needle. First, a vertical needle type probe card is
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`prepared which includes a probe needle having upper and
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`lower portions and an intermediate portion connecting them,
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`and an upper guide plate having a first through hole and
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`Page 13 of 18
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`6,144,212
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`5
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`supporting the upper portion of the probe needle by passing
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`the upper portion through the first through hole, a lower
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`guide plate provided under the upper guide plate, having a
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`second through hole and supporting the lower portion of the
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`probe needle by passing the lower portion through the first
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`through hole, a conductive rubber sheet provided on the
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`upper guide plate, and a printed wiring board provided on
`the conductive rubber sheet, wherein the upper and lower
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`guide plates are spaced apart by a prescribed distance to
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`expose the intermediate portion of the probe needle, and the
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`upper and lower guide plates are displaced in a first hori-
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`zontal direction to curve the intermediate portion of the
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`probe needle. The conductive rubber sheet and the printed
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`wiring board are removed from the upper guide plate. The
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`lower guide plate is moved in an opposite direction from the
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`first horizontal direction so as to vertically align the first and
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`second through holes. A defective probe needle is removed
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`and a new probe needle is inserted instead. The upper and
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`lower guide plates are displaced in the first horizontal
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`direction so as to curve the intermediate portion of the probe
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`needle. The conductive rubber sheet and the printed wiring
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`board are returned on the upper guide plate.
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`The invention according to a twelfth aspect relates to a
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`test method of a wafer using the probe cards.
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`A vertical needle type probe card is prepared which
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`includes: a probe needle having an upper portion, a lower
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`portion, and an intermediate portion connecting the upper
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`and lower portions; an upper guide plate supporting the
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`upper portion of the probe needle by passing the upper
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`portion therethrough; a lower guide plate provided under the
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`upper guide plate and supporting the lower portion of the
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`probe needle by passing the lower portion therethrough; a
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`conductive rubber sheet provided on the upper guide plate;
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`a printed wiring board provided on the conductive rubber
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`sheet; and a conductive path provided in conductive rubber
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`sheet for electrically connecting the upper portion of the
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`probe needle and the printed wiring board and transferring
`an electric signal from an IC to a tester. The probe needle is
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`pressed against a surface of a wafer.
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`The foregoing and other objects, features, aspects and
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`advantages of the present
`invention will become more
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`apparent from the following detailed description of the
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`invention when taken in conjunction with the
`present
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`accompanying drawings.
`BRIEF DESCRIPTION OF THE DRAWINGS
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`FIG. 1 is a cross sectional view of a vertical needle type
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`probe card according to the present invention.
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`FIGS. 2A and 2B are views for describing in detail a probe
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`needle used for the vertical needle type probe card according
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`to the present invention.
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`FIG. 3 shows the relationship between the needle pressure
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`and the displacement of the vertical needle type probe card
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`according to the present invention.
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`FIG. 4 is a cross sectional view of an upper guide plate
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`used for the vertical needle type probe card according to the
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`present invention.
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`FIG. 5 is a plan view of the upper guide plate.
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`FIG. 6 is a plan view showing another embodiment of the
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`upper guide plate.
`FIG. 7 is a cross sectional view of a lower guide plate.
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`FIG. 8 is a plan view of the lower guide plate.
`FIGS. 9 to 12 show first to fourth steps of a method of
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`manufacturing the vertical needle type probe card according
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`to the present invention.
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`5
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`10
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`15
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`20
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`25
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`30
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`35
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`45
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`55
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`60
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`65
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`Page 14 of18
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`6
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`FIG. 13 is a cross sectional view of a printed wiring board
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`used for the vertical needle type probe card according to the
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`present invention.
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`FIG. 14 is a plan view of the printed wiring board.
`FIG. 15 is a cross sectional view of a conductive rubber
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`sheet used for the vertical needle type probe card according
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`to the present invention.
`FIG. 16 shows the finished state of the vertical needle type
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`probe card according to the present invention.
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`FIG. 17 is a view for describing functions and effects of
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`FIG. 18 is a view for describing functions and effects of
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`another example of the conductive rubber sheet used for the
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`present invention.
`FIGS. 19 to 23 show first to fifth steps of a method of
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`replacing a defective needle according to the present inven-
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`FIG. 24 is a cross sectional view of a conventional
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`cantilever type probe card.
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`FIG. 25 shows the relationship between the displacement
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`lever type probe card.
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`FIG. 26 shows the directions of the needle pressure and
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`the displacement of the cantilever type probe card.
`FIG. 27 shows a cross sectional view of a conventional
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`cantilever type probe card having a 4x4 structure.
`FIG. 28 is a cross sectional view of a conventional vertical
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`needle type probe card.
`DESCRIPTION OF THE PREFERRED
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`EMBODIMENTS
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`A vertical needle type probe card which facilitates pro-
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`vision of the structures such as 4x4, 4x8 and n (at least 4)><m
`and which can be manufactured easily and at low cost, as
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`well as a method of manufacturing the vertical needle type
`probe card will be described below with reference to the
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`drawings.
`First Embodiment
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`FIG. 1 is a cross sectional view of a vertical needle type
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`probe card according to a first embodiment, showing probe
`needles in the third and fourth rows of the right half of the
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`4x4 structure shown in FIG. 27.
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`Referring to FIG. 1, probe needle 4 includes an upper
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`portion 4a, a lower portion 4c, and an intermediate portion
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`4b connecting them. Upper portion 4a of probe needle 4
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`penetrates an upper guide plate 5. As described below, upper
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`guide plate 5 prevents the rotation of probe needle 4 and
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`fixes probe needle 4. Lower portion 46 of probe needle 4
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`penetrates a lower guide plate 6. Lower guide plate 6
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`positions probe needle 4 to bring the tip of probe needle 4
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`in contact with a pad. These two types of upper guide plate
`5 and lower guide plate 6 are formed of the same silicon
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`compound as an IC chip wafer. For example,
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`formed of silicon nitride Si3N4 and mica-based ceramics at
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`which fine pores are easily formed.
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`A conductive rubber sheet 20 is provided on upper guide
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`plate 5. For example, conductive rubber sheet 20 is Shinetsu
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`Interconnector® MT type from Shinetsu Polymer Company.
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`This is formed by arranging and burying a gold plated metal
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`wiring to high density in soft silicon rubber. The conductive
`rubber sheet causes electrical conduction due to pressure
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`from above and below. As another conductive rubber sheet,
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`Micro Rubber Probe® from Japan Synthetic Rubber Com-
`pany may be used. It causes electrical conduction because
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`Page 14 of 18
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`6,144,212
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`7
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`the rows of metal particles arranged in the silicon rubber
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`sheet in the thickness direction are connected by pressure
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`applied from above and below. A conductive path 21 formed
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`in conductive rubber sheet 20 electrically connects part of
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`probe needle 4 to a land formed at printed wiring board 7.
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`A flat cable or a coaxial cable, not shown, is provided on
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`printed wiring board 7. The flat cable or coaxial cable
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`functions to transfer a signal. Printed wiring board 7, con-
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`ductive rubber sheet 20, upper guide plate 5 and lower guide
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`plate 6 are firmly fixed by a support member 10.
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`Probe needle 4 is pressed against the IC pad on the wafer.
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`The electric signal obtained from the tip of the probe needle
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`which is in contact with the pad is transferred through
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`conductive rubber sheet 20 and printed wiring board 7 to the
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`tester so as to perform the wafer test of the IC.
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`According to the vertical needle type probe card of the
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`embodiment, the probe needle is compact as in the case of
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`a conventional vertical needle, so that the probe needles can
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`be arranged to high density and in a lattice. Therefore, the
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`n><m structure can easily be attained. Since lower guide plate
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`6 which positions probe needle 4 is formed of the same
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`silicon compound as the IC chip wafer, precise alignment is
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`ensured in every temperature environment.
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`The function and operation of parts constituting the
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`vertical needle type probe card according to the embodiment
`will be described in more detail with reference to the
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`drawings.
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`FIGS. 2A and 2B are views for describing a vertical
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`needle in the probe card according to the embodi