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`Samsung Electronics Co., Ltd. v. Demaray LLC
`Samsung Electronic's Exhibit 1019
`Exhibit 1019, Page 1
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`

`

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`U.S. Patent
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`Feb. 24, 2004
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`Sheet 1 of 2
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`US 6,695,954 B2
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`10
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`SOLIITIIZI~
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`Ex. 1019, Page 2
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`Ex. 1019, Page 2
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`

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`U.S. Patent
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`Feb. 24, 2004
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`Sheet 2 of 2
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`US 6,695,954 B2
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`
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`1@)
`@S
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`Z@
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`Ex. 1019, Page 3
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`Ex. 1019, Page 3
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`

`

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`US 6,695,954 B2
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`
`1
`PLASMA VAPOR DEPOSITION WITH COIL
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`SPUTTERING
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`CROSS-REFERENCE TO RELATED
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`APPLICATIONS
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`This is a continuation of my application Ser. No. 08/971,
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`867, filed Nov. 19, 1997 now US. Pat No. 6,375,810,
`entitled PLASMA VAPOR DEPOSITION WITH COIL
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`SPUTTERING,which is a continuation-in-part of applica-
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`tion Ser. No. 08/907382,filed Aug. 7, 1997, now abandoned
`entitled PLASMA VAPOR DEPOSITION WITH COIL
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`SPUTTERING,Attorney Docket 1957/PVD/DV.
`BACKGROUND OF THE INVENTION
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`The present invention relates to the deposition of layers,
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`or films, of metals and metal compounds on a workpiece, or
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`substrate, during fabrication of integrated circuits, display
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`components, etc.
`In connection with the fabrication of
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`integrated circuits, the substrate may be constituted by one
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`or more semiconductor wafers, while in the case of fabri-
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`cation of a display, such as a liquid crystal display,
`the
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`substrate may be one or more glass plates. The substrate
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`could also be a hard disc that will be used for data storage,
`or read/write heads for a disc drive.
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`It
`is known to deposit
`layers on such substrates by
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`processes such as physical vapor deposition. By way of
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`example, as described in copending application Ser. No.
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`08/680,335 abandoned, filed Jul. 10, 1996 (Attorney Docket
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`No. 1390CIP/PVD/DV), entitled “Coils for Generating a
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`Plasma and for Sputtering” by Jaim Nulmanetal., which is
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`assigned to the assignee of the present application and
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`incorporated herein by referencein its entirety, processes of
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`this type may be performed in apparatus including a depo-
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`sition chamber which contains a target, a coil and a support
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`for the substrate. The target is made of a material such as a
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`metal which will form a metal layer or the metal component
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`of a metal compoundlayer. The coil will be supplied with an
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`RF current that will generate, within the chamber, an RF
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`electromagnetic field.
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`When a gas is introduced into the chamberat an appro-
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`priate pressure, a dense plasma (10'’-10"° ions/em*) may be
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`ignited inside the chamberby the RF electromagnetic field.
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`The target may be associated with a magnetic field produc-
`45
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`ing device, such as a magnetron, and may be biased by a DC
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`or RF voltage applied to the target from a voltage source.
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`The magnetic field traps electrons, while the DC bias voltage
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`on the target attracts ions to the target. These ions dislodge,
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`or sputter, atoms or clusters of atoms of material from the
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`target. The sputtered atomstravel toward the support and a
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`certain proportion of these atoms are ionized in the plasma.
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`The support provides a surface for supporting the substrate
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`and may bebiased, usually by an AC source, to bias the
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`substrate with a polarity selected to attract ionized target
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`material to the substrate surface. The bottom coverage of
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`high aspect ratio trenches and holes on the substrate can be
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`improved by this substrate bias. Alternatively, the chamber
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`may sputter target material without an RF coil or other
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`devices for generating an ionizing plasmasuch that substan-
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`tially all the material deposited is not ionized.
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`Although the RF electromagnetic field is generated by
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`applying an alternating RF currentto the coil, a DC potential
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`may be induced in the coil as described in the aforemen-
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`tioned copending application Ser. No. 08/680,335. This
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`potential which maybereferred to as a self bias, combines
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`with the RF potential on the coil. The combined DC and RF
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`potentials have the net effect of attracting ions from the
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`2
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`plasma to the coil. If the coil is made of the same material
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`as the target, the coil can constitute an additional source of
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`deposition material which will be sputtered from the coil by
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`ions attracted from the plasma to be deposited on the
`substrate.
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`If a film consisting essentially of only the sputtered
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`material is to be formed on a substrate, then the gas within
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`the chamber is preferably nonreactive with respect to the
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`sputtered atoms. If, on the other hand, a compound film
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`formed by a chemical reaction of the target material with
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`another constituent is to be formed, the gas introduced into
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`the chamber may have a composition selected to react with
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`the sputtered target material ions and atoms to form mol-
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`ecules of the compound, which are then deposited on the
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`substrate. Alternatively, the gas may react with the target
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`material while or after it is deposited.
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`For example, plasma and nonionizing plasma sputtering
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`deposition processes of the type described above can be used
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`to deposit either a pure metal or metal alloy, such as
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`titanium,
`tantalum, aluminum, copper, aluminum-copper,
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`etc., or a metal compound, such as titanium nitride (TiN),
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`aluminum oxide (Al,O,), etc. Also, other non metallic
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`materials may be deposited such as silicon and silicon
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`dioxide. For deposition of a pure metal or metal alloy, the
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`target, and possibly the coil, will be made of this metal and
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`the plasma gas is preferably a non-reactive gas, i.e. a gas
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`such as argon, helium, xenon,etc., which will not react with
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`the metal. For deposition of a metal compound,the target,
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`and possibly the coil, will be made of one componentof the
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`compound,
`typically the metal or metal alloy, and the
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`chamber gas will include a reactive gas composed of, or
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`containing,
`the other component or components of the
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`compound, such as nitrogen or oxygen. The sputtered metal
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`reacts with gas atoms or molecules to form the compound,
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`molecules of which are then deposited on the substrate. In
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`the same manner, a nonmetallic target material may be
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`sputtered in a nonreactive environmentto deposit relatively
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`pure target material onto the substrate. Alternatively, the
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`target material may be sputtered in a reactive environmentto
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`produce on the substrate a layer of a compoundofthe target
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`material and a reactive component. Hereinafter, a compound
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`formed of a target or coil material and a reactive component
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`will be referred to as a reaction compound, whether the
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`sputtered material is metallic or otherwise.
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`Onefactor determining the performanceof such apparatus
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`is the density of gas, and hence the density of the plasma, in
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`the chamber. A relatively dense plasma can provide an
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`increased ionization rate of the sputtered material atoms,
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`thus improving bottom coverage of trenches and holes on
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`the substrate. However, under high pressure conditions,
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`material sputtered from the target tends to be deposited
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`preferentially in a central region of the substrate support
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`surface. Such nonuniformity can often increase at higher
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`deposition rates or higher pressures.
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`This nonuniformity is disadvantageous because the thick-
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`ness of the deposited layer preferably should correspond to
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`a nominalvalue, within a narrow tolerance range, across the
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`entire support surface. Therefore, when the substrate is, for
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`example, a wafer which will ultimately be diced into a
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`plurality of chips, and there is a substantial variation in the
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`thickness of the layer across the wafer surface, many of the
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`chips may becomerejects that must be discarded.
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`As described in the aforementioned copending applica-
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`tion Ser. No. 08/680,335, it has been recognized that mate-
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`rial sputtered from the coil may be used to supplementthe
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`deposition material sputtered from the primary target of the
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`Ex. 1019, Page 4
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`Ex. 1019, Page 4
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`

`

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`US 6,695,954 B2
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`A further specific object of the invention is to facilitate
`chamber. Because the coil can be positioned so that material
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`deposition of a layer of a target material such as an elemental
`sputtered from the coil tends to deposit more thickly at the
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`metal or metal alloy in a single deposition apparatus a short
`periphery of the wafer, the center thick tendency for material
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`time after completion of deposition of a layer of a reaction
`sputtered from the primary target can be compensated by the
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`compound of the target material and another constituent.
`edge thick tendency for material sputtered from the coil. As
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`A still more specific object of the invention is to rapidly
`a result, uniformity can be improved.
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`remove reaction compound material which has been depos-
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`The quantities of material sputtered from the coil and the
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`ited on the target or coil in a deposition chamber subsequent
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`target are a function of several factors including the DC
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`to a reaction compoundlayer deposition process andprior to
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`powerapplied to the target and the RF powerapplied to the
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`10
`a target material layer deposition process which does not
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`coil. However, the freedom to adjust these and other factors
`include a reactive constituent.
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`may be limited in some applications by the requirements of
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`The above and other objects are achieved, according to
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`other process parameters which are often interdependent.
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`the present invention, by a method and apparatus for sputter
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`Thus, a need exists for further control over the quantity of
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`depositing a layer on a substrate in which following depo-
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`material sputtered from the coil to facilitate further increases
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`sition of a layer of reaction compound formed from con-
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`stituents which includes a reactive material and a material
`in the degree of uniformity of deposition that may be
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`achieved.
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`sputtered from a target or coil, a layer of material sputtered
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`In addition, when such apparatus is used to deposit a
`from the same target or coil may be deposited in the same
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`chamber in which the subsequentlayer is substantially free
`reaction compound layer, some of the reaction compound
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`of contamination by the reaction compound orthe reactive
`typically also coats the target and the coil. For example,
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`material.
`In the illustrated embodiment,
`this may be
`when titanium nitride is deposited in a chamber having a
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`achieved by removing the reactive material from the sputter
`titanium metal target in a nitrogen atmosphere,
`titanium
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`chamberfollowing the deposition of the reaction compound,
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`nitride typically coats the target and coil. Therefore, if it
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`introducing a non-reactive gas into the enclosure, and sput-
`were then attempted to deposit a pure target material layer,
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`tering substantially all reaction compoundfrom the target or
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`ie., a layer of just titanium, in the same apparatus,
`the
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`coil which provided the source of the sputtered material. As
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`reaction compound molecules of titanium nitride would
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`a consequence, the same chamberis then ready to deposit
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`likely also be sputtered from the target, and also from the
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`another layer except that the layer may be a layer consisting
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`coil, and thus could contaminate the titantum metal layer.
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`essentially of only material sputtered from the source. In this
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`Therefore,
`it has generally not been practical to sputter
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`manner, a chamber may be used to deposit a metal com-
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`deposit a metal or metal alloy layer fromatarget of the same
`30
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`pound such as titanium nitride and then after sputter
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`material immediately after having deposited a metal com-
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`cleaning, be ready to deposit a layer of relatively pure
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`pound layer in the same apparatus.
`titanium in the same chamber without substantial contami-
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`Some efforts have been made to deal with this drawback
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`nation by titanium nitride.
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`by sputtering away the metal compoundlayer coating on the
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`This aspect of the invention is particularly applicable to
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`target, and covering over the metal compound layer coating
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`apparatus which includes a chambercontaining a sputtering
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`on the coil with a layer of the metal sputtered from the target,
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`target and a plasma generating coil. According to the
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`this procedure being known as “pasting”. However, such
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`invention, a suitable voltage is applied to the coil, while the
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`attempts have generally been found to be unacceptably
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`chamber is filled with a non-reactive gas and does not
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`costly and time-consuming, and otherwise unsatisfactory.
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`contain any substrate,
`to produce a plasma which will
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`Therefore, facilities in which layers of a metal and layers
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`rapidly sputter deposited metal compound material from the
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`of a compoundof that metal are to be deposited on substrates
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`target, and possibly also from the coil.
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`are typically equipped with two apparatuses, each for depos-
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`The above and other objects are further achieved, accord-
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`iting a respective type of layer. This, of course, may entail
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`ing to the present invention, by a method and an apparatus
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`twice the investment cost associated with one apparatus.
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`for depositing a layer of a material which contains a metal
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`Moreover, in production systems having multiple chambers
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`on a workpiece surface in which both RF energy is supplied
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`coupled to a central transfer chamber, valuable perimeter
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`to a coil
`to generate a plasma to ionize the deposition
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`space of the transfer chamber is occupied by an extra
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`material, and a separate DC bias is applied to the coil to
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`chamberthat could otherwise be used by another chamberto
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`the coil sputtering rate.
`In the illustrated
`control
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`increase throughput or provide additional processes.
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`embodiment, a DC voltage source is coupled to the coil
`BRIEF SUMMARY OF THE INVENTION
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`through an RFfilter to provide a DC bias potential which is
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`different in magnitude from the coil DC self bias potential
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`It is an object of the present invention to alleviate the
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`whichresults from the applied RF power. In this manner, the
`above difficulties.
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`coil bias potential and hence the coil sputtering rate may be
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`Amore specific object of the invention is to improve the
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`controlled with a degree of independence from the RF power
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`uniformity with which a layer of material is deposited on a
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`applied to the coil.
`substrate.
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`In another aspect of the invention, the coil may be shaped
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`Another object of the invention is to achieve such
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`and positioned to permit use as the sole source of sputtered
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`improvementin uniformity without any significant increase
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`material within said chamber while maintaining good uni-
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`in the cost or complexity of the deposition apparatus.
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`formity. As a consequence, in some applications, the need
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`Still another object of the invention is to improve depos-
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`for a separate target and associated magnetron may be
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`ited film uniformity while, at the same time, improving
`eliminated.
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`apparatus throughput.
`BRIEF DESCRIPTION OF THE SEVERAL
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`Still another object of the invention is to improve depos-
`VIEWS OF THE DRAWINGS
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`ited film uniformity while at the same time reducing the cost
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`and complexity of the deposition apparatus.
`FIG. 1 is a simplified, elevational, cross-sectional view of
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`Still another object of the invention is to allow added
`deposition apparatus constructed according to one embodi-
`ment of the invention.
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`control of the rate of deposition of material on a substrate.
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`Ex. 1019, Page 5
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`Ex. 1019, Page 5
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`

`

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`US 6,695,954 B2
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`6
`5
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`illustrated embodiment, this bias will have a negative polar-
`FIG. 2 is a circuit diagram illustrating electrical systems
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`ity and can be of the order of -100 volts. If coil 6 is made
`associated with the apparatus of FIG. 1.
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`of a sputterable material, then ions in the plasma will be
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`FIG. 3 is a view similar to that of FIG. 1 showing another
`attracted to coil 6 as a result of the DC self bias and these
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`embodimentof deposition apparatus according to the inven-
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`ions will sputter, or dislodge, atoms or clusters of atoms of
`tion.
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`material from the surface of coil 6. Therefore, by making
`FIG. 4 is a cross-sectional view of another embodiment of
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`coil 6 of the same material as target 4, the rate of generation
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`a coil which may be employed in apparatus according to the
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`of material for deposition on the workpiece surface can be
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`present invention.
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`increased. Still further, the target and coil 6 provide spatially
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`separated sources of sputter material, which can be used to
`DETAILED DESCRIPTION OF EMBODIMENTS
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`improve film properties.
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`Since coils, such as coil 6, may be dimensioned and
`FIG. 1 showsthe basic components of one embodiment of
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`positioned so as to be outside the periphery of workpiece
`a deposition apparatus constructed according to a first pre-
`ferred embodiment of the invention.
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`support surface 14, it has been found that sputtered material
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`originating from coil 6 will tend to be deposited thicker in
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`Theillustrated apparatus includes a deposition chamber2,
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`the peripheral region of the workpiece support surface than
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`a sputtering target 4, a plasma generating coil 6 and a
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`in the center region. This is beneficial because in many
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`workpiece support 8, all of which are disposed within
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`installations, and particularly those operating with high
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`chamber 2. Outside of chamber 2, and abovetarget 4, there
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`pressures, material sputtered from target 4 tends to be
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`is provided a magnetic field generating assembly, such as a
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`deposited thicker in the central region of the workpiece
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`magnetron, 10. Target 41s made of a conductive material, for
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`the
`support surface than in the peripheral region. Thus,
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`example a metal, such as titantum, whichis to be sputtered
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`sputtering of deposition material from coil 6 can help to
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`and then deposited on a workpiece provided on a workpiece
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`counteract the tendency of material sputtered from target 4
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`support surface 14 of workpiece support 8. Other materials
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`to be deposited to a greater thicknessin the central region of
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`which are currently deposited in such apparatus include
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`the workpiece support surface.
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`metals and alloys such as aluminum, copper,
`tantalum,
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`To obtain the best deposition uniformity, the coil sputter-
`aluminum-copper alloys and metal compounds such as
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`titanium nitride and tantalum nitride.
`ing rate is preferably sufficiently high relative to the target
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`sputtering rate to compensate for any deposition nonunifor-
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`In order to make possible the generation of a plasma
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`mity of material from the target. One way this might be
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`within chamber 2, a suitable quantity of an ionizable gas,
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`achieved is to reduce the target sputtering rate. But a lower
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`such as argon, is introduced into the chamberthrough a port
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`target sputtering rate usually results in a lower deposition
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`15 and RF poweris supplied to coil 6 from an RF power
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`rate on the substrate, and therefore a lower system through-
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`supply 16 via an appropriate matching network 20. One end
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`put. Another approachis to increase the coil sputtering rate
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`of coil 6 is connected to matching network 20 and the other
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`by increasing RF powerlevel. However, the optimum value
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`end of coil 6 is connected to ground via a DC blocking
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`of the RF power applied to the coil is a function of several
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`capacitor 22 (FIG. 2). The RF power supplied to coil 6
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`process parameters and chamber design considerations.
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`results in the generation of an electromagnetic field that
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`Hence, in many applications a particular RF power level
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`produces a plasma. Assembly 10 also contributes to genera-
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`which mayprovide a useful self bias on the coil 6 to provide
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`tion of a plasma within chamber 2. In the absence of RF
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`a desired coil sputtering rate, may have a disadvantageous
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`current in coil 6, a plasma of lower density can also be
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`effect on these other factors or may be higher than that which
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`generated in the vicinity of target 4 and magnetron 10 by
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`may be provided by the particular system. Thus, the RF
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`applying a DC or RFvoltage to target 4.
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`powerlevel which provides the best uniformity of deposi-
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`Under these conditions, a material to be deposited on a
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`tion may not be appropriate for the particular chamber or
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`substrate disposed on surface 14 will be sputtered from
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`may adversely affect other film properties.
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`target 4, at least partially ionized in the plasmafield and
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`In accordance with one aspect of the invention, the coil
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`directed to the workpiece.
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`sputtering rate may be controlled with a degree of indepen-
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`The sputtering of material from target 4 is aided by
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`dence of the RF powerlevel. In the illustrated embodiment,
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`biasing target 4, by means of a biasing voltage source 24,
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`not only is RF energy supplied to the coil to generate a
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`such as a DC source, with a polarity to attract ions in the
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`plasma to ionize the deposition material, but a separate DC
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`plasma. The attracted ions impact on target 4 and dislodge
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`bias is also applied to the coil to separately control the coil
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`atomsor clusters of atoms of the material making up target
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`bias level and hence control the coil sputtering rate. As a
`4.
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`result, one need not be limited to the DC self bias which is
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`A proportion of the atoms sputtered from target 4 will be
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`created whenonly an alternating RF currentis applied to the
`coil.
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`ionized in the plasma to become, in the case of a metal,
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`positive ions. In order to promote deposition of these posi-
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`Thus, according to the invention, the DC bias on coil 6 is
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`tive ions on the workpiece surface, workpiece support 8 is
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`altered, independently of the magnitude and frequency of
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`connected to a suitable bias voltage source 26 such as an AC
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`the RF power delivered by supply 16, by also connecting
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`source. In the illustrated embodiment, sources 24 and 26
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`coil 6 to a DC voltage source 30. Preferably, an RF blocking
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`cause a negative bias to develop on the target 6 and the
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`filter 32 is connected between coil 6 and DC voltage source
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`substrate 14, respectively.
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`30. Such an RF blocking filter, when designed properly, can
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`Since it is often desired to be able to move workpiece
`eliminate or reduce substantially RF current flowing to the
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`support 8 vertically within chamber 2, while the interior of
`DC source 30. Filter 32 provides a negligibly small DC
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`chamber remains sealed, workpiece support 8 may be
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`impedance between source 30 and coil 6 so that coil 6 will
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`coupled to chamber 2 by an appropriate bellows 28.
`be placed at a DC bias essentially equal to the voltage
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`provided by voltage source 30. While voltage source 30 is
`When the only voltage applied to coil 6 is an alternating
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`RFvoltage, it is believed that a DC self bias is inherently represented schematically byabattery, it will be appreciated
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`induced on coil 6 across blocking capacitor 22. In the
`that any suitable DC voltage source can be employed and the
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`Ex. 1019, Page 6
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`Ex. 1019, Page 6
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`US 6,695,954 B2
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`7
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`output voltage thereof can be adjusted to produce the desired
`level of DC bias on coil 6.
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`While the RF generator 16 and matching network 20 are
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`preferably coupled to one end of the coil 6, the DC source
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`30 and RF filter 32 may be coupled to the coil anywhere
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`along its length. For example, as shown in FIG. 2, the DC
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`source 30 and filter 32 may be coupled to end of coil 6 to
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`which is the end to which the blocking capacitor 22 is
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`coupled which is opposite to the end to which RF generator
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`16 is coupled.
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`As an alternative to the arrangementillustrated in FIG. 1,
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`it will be appreciated that a separate voltage source 30 need
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`not be provided and RFfilter 32 could, instead, be connected
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`between coil 6 and the DC voltage source 24. Since there is
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`no DC path from coil 6 to ground, the current flow between
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`voltage source 30 and coil 6 will be a function primarily of
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`the sputtering current as ions impactthe coil 6 and secondary
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`electrons are emitted into the plasma. Therefore, voltage
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`source 30, or voltage source 24, if used in place of source 30,
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`preferably should be capable of producing a sufficiently high
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`output current to accommodate the anticipated sputtering
`rate.
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`FIG. 2 is a circuit diagram illustrating one example of
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`circuitry employed for supplying RF current and a DC bias
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`voltage to coil 6. Here coil 6 is represented by its equivalent
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`circuit, which is a series arrangement of an inductance and
`a resistance.
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`Matching network 20 is a conventional network which
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`includes two adjustable capacitors and an inductor. As is
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`known, the purpose of circuit 20 is to match the output
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`impedance of RF power supply 16 to the impedance of the
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`load to which it is connected. In addition, the DC blocking
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`capacitor 22 connected between coil 6 and ground servesto
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`prevent flow of a DC current from coil 6 to ground. To
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`improve deposited layer uniformity, RF frequency and
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`powerlevels may be periodically altered during deposition.
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`In addition, impedances of the components of the matching
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`network and blocking capacitor ma