United States Patent
`Ohmi et al.
`
`[19]
`
`[54] PARALLEL PlAI'E SPUTI'ERlNG DEVICE
`).\'ITH RF POWERED AUXILIARY
`ELECTRODES AND APPLIED EXTERNAL
`MAGNETIC FJELD
`
`[75]
`
`Inventors: Tadahiro Ohmi, 1-17-301.
`Komegabulmro 2-chome. Aoba-ku.
`Sendai-shi, Miyagi-ken 980-0813;
`Masaki Hirayama, Miyagi-ken;
`Haruyuki Takano, Miyagi-ken; Yustlke
`Hirayama, Miyagi-ken, all of Japan
`
`[73] As.signee; Tadahiro Ohmi, Miyagi-ken, Japan
`
`[21] Appl. o. : 09/035,325
`
`[22] Filed:
`Foreign Application Priority Data
`
`Mar. 5, 1998
`
`[30]
`
`[51]
`[52]
`
`Mar. 7, 1997
`
`J~pan .... , ............................. 9-070431
`
`(JP]
`................................. .................... C23C 14/34
`Int. Cl.7
`.S. Cl . .................. .............. 204/298.06; 204/298.08;
`204/298.14
`l58] Field of Search ........... .............. 204/192.12, 298.0J,
`204/298.02, 298.06, 298.07, 298.08, 298.16,
`298.17, 298.19, 298.14
`
`1111111111111111111111 IIIII IIIII IIIII IIIII IIIII IIIII IIIII IIIIII Ill lllll 1111
`US006153068A
`[11] Patent umber:
`[45] Date of Patent:
`
`6,153,068
`Nov. 28, 2000
`
`5,316,645
`5,431,799
`5,800,688
`
`5/1994 Yamagami el al. ................ 204/298.06
`7/1995 Mosely el al. ..................... 204/298.06
`9/1998 La11tsma11 et al. ................. 204/298.11
`
`FOREIGN PATENT DOCUME TS
`
`WO 89/06437
`6-252059
`08319564
`WO 98/01898
`
`7/1989
`9/1994
`12/1996
`1/1998
`
`Japan ................ ............. HOlL 21/31
`Japan .......... ...... ... ... ... .. £-IOlL 21/205
`Japan ................ ............. C23C 14/34
`Japan ......................... HOtL 21/3065
`
`Primary Examiner-Nam Nguyen
`Assistant Examiner-Gregg Cantelmo
`andall J. Knuth
`Attorney, Agent, or Firm
`
`[57]
`
`ABSTRACT
`
`The present invention provides a sputtering device provided
`with two electrodes I and II of parallel plate type within a
`vessel inside which pressure can be reduced, wherein: a
`target to be sputtered is placed on said electrode I, and a base
`body on which a film is to be deposited is placed on said
`electrode II, with the target and the base body being opposed
`to each other; a process gas is introduced into said vessel
`from a gas supply system; rawo frequency power is applied
`to said target through at least said electrode I so as to excite
`plasma between the electrode I and the electrode II ; char(cid:173)
`acterize-cl in ihat: outside said vessel, is provided a means for
`introducing magnetic field horizontal at least to a surface to
`be sputtered of said target.
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`5,178,739
`
`1/1993 Bames et al. ...................... 204/192.12
`
`2 Claims, 9 Drawing Sheets
`
`113
`Rf POWER 9.FPL Y
`
`111 OC POWER SJPPLY
`
`121
`
`123 1..----, , - - - - - 122
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`fWl
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`124~
`MOVAIU lP AN) DOWN 1
`
`--z..-- 120
`
`110
`
`=
`
`Page 1 of 13
`
`APPLIED MATERIALS EXHIBIT 1020
`
`

`

`l MOVABLE UP ArO DOWN
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`SYSTEM
`GAS SLPPLY
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`OWER SUPPLY
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`
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`PUMP
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`
`,------, ,----rt 122
`
`123
`
`Page 2 of 13
`
`

`

`U.S. Patent
`US. Patent
`
`Nov. 28, 2000
`Nov. 28, 2000
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`Sheet 2 0f 9
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`6,153,068
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`Nov. 28, 2000
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`Sheet 3 of 9
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`6,153,068
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`Page 4 of 13
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`U.S. Patent
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`Nov. 28, 2000
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`U.S. Patent
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`Nov. 28, 2000
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`Sheet 9 of 9
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`

`

`6,153,068
`
`1
`PARALLEL PLATE SPUTTERING DEVICE
`
`
`
`
`WITH RF POWERED AUXILIARY
`
`
`
`
`ELECTRODES AND APPLIED EXTERNAL
`
`
`
`MAGNETIC FIELD
`
`BACKGROUND OF THE INVENTION AND
`
`
`
`
`
`DESCRIPTION OF RELATED ART
`
`
`
`
`
`
`1. Technical Field
`
`
`The present invention relates to a sputtering device, and
`
`
`
`
`
`
`
`in particular to a sputtering device provided with a means for
`
`
`
`
`
`
`
`
`
`introducing magnetic field which is horizontal to a target
`
`
`
`
`
`
`surface to be processed by sputtering, so as to enable to
`
`
`
`
`
`perform uniform sputtering all over the surface of the target.
`
`
`
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`
`
`
`
`
`2. Background Art
`
`
`
`
`
`Recently, as chip sizes of DRAM, MPU etc. become
`
`
`
`
`larger, silicon substrates used as their base bodies tend to
`
`
`
`
`
`
`
`
`have larger diameters. For the case that a thin film is to be
`
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`formed on a larger-diameter base body by sputtering, it is
`
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`desired to develop a sputtering device which can use a target
`
`
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`
`
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`
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`having a larger diameter corresponding to a size of a base
`
`
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`body, and can form a homogeneous deposit film having
`
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`
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`uniform film thickness on the base body.
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`As a conventional sputtering device, is mentioned an RF
`
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`sputtering device FIG. 6) which has parallel plate electrodes
`
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`and sputters a target while applying RF bias to the target, or
`
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`a magnetron sputtering device (FIG. 7) which has such
`structure that magnetic field is generated from a back surface
`
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`of a target, and which applies RF bias to the target while
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`applying that magnetic field, so as to generate higher—density
`plasma on the surface of the target.
`
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`FIG. 9 shows a result of investigating sputtering capacity
`of the above-described RF sputtering device and magnetron
`
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`
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`sputtering device. Namely, after application of radio fre-
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`quency power (13.56 MHz) to an Al target (150 mmq)) for
`100 hours, scraped amounts of the target were investigated
`
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`at 8 points on a surface of the target at intervals of 20 mm
`
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`in the diametral direction to obtain the result. From this
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`result,
`is seen that a magnetron sputtering device has
`it
`
`
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`
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`higher sputtering capacity than a RF sputtering device. As
`
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`
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`
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`
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`shown in FIG. 8, however,
`in the magnetron sputtering
`
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`
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`device, directions of the magnetic field generated on the
`
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`target surface are not uniform, and accordingly, on the target
`surface, strong plasma is generated only in a limited space
`
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`enclosed by magnetic flux.
`
`
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`One method of avoiding this problem that is known in the
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`art utilizes a yoke structure design rotating a magnet mecha-
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`nism on a back surface of a target, and the like. However, in
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`the case that yoke structure design is employed, it leads to
`complication of the hardware, and in the case that
`the
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`magnet mechanism is rotated, plasma is rotated and accord-
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`ingly film substance grown on a substrate becomes weak in
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`stress resistance.
`In addition, deposit film with uniform
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`quality can not necessarily be obtained on a base body.
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`OBJECT AND SUMMARY OF THE INVENTION
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`An object of the present invention is to provide [provided]
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`a sputtering device which provides a [can make] plasma
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`with a uniform density [uniform for a target] and deposits a
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`film with a [can form deposit film having] uniform film
`quality on a base body.
`
`
`
`The present invention provides a sputtering device pro-
`
`
`
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`
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`vided with two electrodes I and II of parallel plate type
`
`
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`
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`within a vessel
`inside which pressure can be reduced,
`
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`wherein: a target to be sputtered is placed on said electrode
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`I, and a base body on which a film is to be deposited is
`
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`1O
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`15
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`30
`
`U.)Ln
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`4O
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`45
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`50
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`55
`
`60
`
`65
`
`2
`placed on said electrode II, with the target and the base body
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`being opposed to each other; a process gas is introduced into
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`said vessel from a gas supply system; radio frequency power
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`is applied to said target through at least said electrode I so
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`as to excite plasma between the electrode I and the electrode
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`II; characterized in that: outside said vessel, is provided a
`means for introducing magnetic field horizontal at least to a
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`surface to be sputtered of said target.
`
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`BRIEF DESCRIPTION OF THE DRAWINGS
`
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`FIG. 1 is a schematic sectional View showing an embodi-
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`ment of the sputtering device according to the present
`
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`invention;
`FIG. 2 is a schematic plan View showing a case that a pair
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`of permanent magnets are used as a means for introducing
`magnetic field shown in FIG. 1;
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`FIG. 3 is a schematic plan View showing a case that a
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`dipole ring magnets (DRM) is used as the means for
`introducing magnetic field shown in FIG. 1;
`
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`FIG. 4 is a graph showing a result of investigation of
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`scraped amounts of the target in the sputtering device of the
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`present invention;
`
`FIG. 5 is a graph showing specific resistance of the
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`deposit film;
`
`FIG. 6 is a schematic sectional View showing an example
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`of the conventional RF sputtering device;
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`FIG. 7 is a schematic sectional View showing an example
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`of the conventional magnetron sputtering device;
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`FIG. 8 is a schematic sectional View showing a state of
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`magnetic field generation in the magnetron sputtering device
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`of FIG. 7; and
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`FIG. 9 is a graph showing a result of investigation of
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`scraped amounts of the target in the conventional sputtering
`device.
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`(Symbols)
`100 vessel, 101 means for introducing magnetic field, 102
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`electrode I,
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`103 target, 104 auxiliary electrode A, 105 base body,
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`106 electrode II, 107 auxiliary electrode B,
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`108—110 band eliminators (BB), 111 and 112 low—pass
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`113—115 AC power supplies, 116—118 matching circuits,
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`119 and 120 DC power supply, 121 gas supply system,
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`122 turbo—molecular pump, 123 dry pump, and 124
`exhaust system,
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`200 vessel, 230a, 23% permanent magnets, 300 vessel,
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`303 target, 330 permanent magnet, 601 sputtering chamber,
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`602 anode, 603 target, 604 shutter, 605 shield, 606 gas
`supply port, 607 exhaust port, 608 matching circuit, 609 RF
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`power supply, 610 matching box, 703 target, 704 erosion
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`position, 705 shield, 706 magnet, 707 magnet support, 708
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`power supply line, 709 cooling water inlet, 710 cooling
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`water exit, 711 insulating material, 803 target, 806 magnet,
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`807 magnet support, 812 leakage flux
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`DETAILED DESCRIPTION OF THE
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`PREFERRED EMBODIMENT OF THE
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`INVENTION
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`(Best Mode for Carrying Out the Invention)
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`FIG. 1 is a schematic sectional View showing an example
`of the sputtering device according to the present invention.
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`In FIG. 1, reference numeral 100 refers to a vessel, inside
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`which pressure can be reduced, 101 to a means for intro-
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`ducing magnetic field, 102 to an electrode I, 103 to a target,
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`104 to an auxiliary electrode A, 105 to a base body, 106 to
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`Page 11 ofl3
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`Page 11 of 13
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`6,153,068
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`an electrode II, 107 to an auxiliary electrode B, 108—110 to
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`band eliminators (B.E.), 111 and 112 to low—pass filters,
`113—115 to AC power supplies, 116—118 to matching
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`circuits, 119 and 120 to DC power supply, 121 to a gas
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`supply system, 122 to a turbo-molecular pump, 123 to a dry
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`pump, and 124 to an exhaust system.
`In FIG. 1, the vessel 100 can be reduced in pressure to
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`such a level that plasma process can be carried out in its
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`inside. To that end, the gas supply system 121 introduces gas
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`into the vessel 100 for plasma excitation, and the exhaust
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`system 124 can reduce the pressure inside the vessel.
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`As wall surface material of the vessel 100, Al alloy or the
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`like may be used. Preferably, however, nitrided material (for
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`example, AlN) may be used, taking it into consideration that
`water content released from the chamber wall surface etc.
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`deteriorates adherence between material to be formed with
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`film and the base body to be processed, and that other
`material than the target base body to be processed is sput-
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`tered. This is not limited to the chamber wall surface, and,
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`as the electrodes and other materials within the chamber,
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`materials which do not release water content and have
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`higher plasma resistance should be used as far as possible.
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`Candidates of conductive material are glassy carbon, SiC,
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`etc. and candidates of insulating material are AlN, SiN, etc.
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`Selection of material is decided taking into consideration
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`thermal conductivity, ratio of electric field strength on a
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`surface, and the like.
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`The means for introducing magnetic field 101 is installed
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`outside the vessel 100, can be moved in upward and down-
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`ward directions and in rotational direction, and produces
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`uniform magnetic field on the target 103 by introducing
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`magnetic field horizontal to a surface to be sputtered of the
`target 103.
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`The electrode 1 102 has a function of holding the target
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`103, while it
`is an electrode for exciting plasma. This
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`electrode I 102 is electrically connected with the AC power
`supply 113 through the matching circuit 116, and with the
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`DC power supply through the low-pass filter (IPF). This is
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`provided for controlling energy of ions radiated onto the
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`target 103. When the target is not conductive material, this
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`energy is controlled by varying frequency and power of the
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`radio frequency power supply.
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`The target 103 is a parent material to form a deposit film
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`on a base body 105 placed in an opposite position. As the
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`target 103, semiconductor material such as Si, metal mate-
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`rial such as W, Ta, and insulating material such as SiO2 can
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`be used preferably, for example. Further, the material used
`as the target 103 is not limited to one to be directly formed
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`as a film. Material which is different in chemical composi-
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`tion or which is to constitute a part of composition of the
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`material of the aimed film may be used and reacted with gas
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`existing within the plasma, so at to form the desired deposit
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`film. By carrying out such a method of forming deposit film,
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`i.e., a reactive sputtering method, it is possible, for example,
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`to form SiN film by using Si as the target 103 and N2 as the
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`gas for producing plasma.
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`The auxiliary electrode A 104 is provided in the area
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`outside the outer peripheral end of the target, and is con—
`tacted with the electrode I 102. The connection between the
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`electrode I 102 and the auxiliary electrode A 104 may be of
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`an electrical conductive state, or, alternatively, may be
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`connected through a condenser to have electrical capacity. In
`particular, in the latter case, the auxiliary electrode A 104 is
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`not easily sputtered. The auxiliary electrode A 104 has an
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`effect of enlarging generation space for the plasma excited
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`on the target 103 toward the inside of the surface, and is
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`greatly different in function from a yoke of magnetic mate-
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`1O
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`U.)Ln
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`4
`rial employed in the conventional technique as a means for
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`introducing magnetic field.
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`The base body 105 is a substrate for receiving particles
`etc. sputtered from the target 103 and for depositing a film
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`on it. As the base body 105, for example, Si substrate, SiC
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`substrate, glass substrate, or the like may be used, although
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`it is not limited to these.
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`The electrode II 106 has a function of holding the base
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`body 105, and is connected with the AC power supply 114
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`through the matching circuit 117 as well as connected with
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`the DC power supply 120 through the low-pass filter (LPF)
`112. This is to give self-bias to the base body 105. In the case
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`that the base body 105 is conductive and the material to be
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`formed as the film on the base body 105 is also conductive,
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`only the DC power supply 120 may suffice. In the case that
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`either of them is insulating material, the DC power supply
`120 is not necessary and it is suffice that only the AC power
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`supply 114 is connected.
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`The auxiliary electrode B 107 is located in the area
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`outside the outer peripheral end of the base body 105, and
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`in the position spaced from the base body 105 and the
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`electrode II 106. Further, the auxiliary electrode B 107 is
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`connected with the AC power supply 115 through the
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`matching circuit 118 to apply radio frequency power. This is
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`provided for relaxing bias of the plasma due to application
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`of the magnetic field.
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`The band eliminators (B.E.) 108—110 are band-rejection
`filters, and suitably set in such a manner that only radio
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`frequency power having desirable frequencies are applied to
`the respective electrodes connected, so that the applied radio
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`frequencies are not affect one another.
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`Embodiments
`In the following, the sputtering device according to the
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`present
`invention will be described referring to the
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`drawings, although the present invention is not limited to
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`these embodiments.
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`(Embodiment 1)
`In this embodiment, the sputtering device shown in FIG.
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`1 was used with various means for introducing magnetic
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`field 101 to investigate sputtering capacities. Sputtering
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`capacity was evaluated by scraped amounts of an Al target
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`(150 mm¢) at eight points on the surface of the target at
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`intervals of 20 mm in the diametral direction, after applying
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`radio frequency power (13.56 MHZ) for 100 hours.
`As the means for introducing magnetic field 101, a case
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`of magnetic arrangement shown in FIG. 2 and a case of
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`magnetic arrangement shown in FIG. 3 were investigated. In
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`the magnetic arrangement of FIG. 2, a pair of permanent
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`magnets 230a, 230b are positioned in parallel so that the
`vessel 200 of the sputtering device is located between them.
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`In the magnetic arrangement of FIG. 3, a plurality of
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`permanent magnets 330 are positioned so as to surround the
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`vessel 300 of the sputtering device, which is a case using
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`“so-called” dipole ring magnets (DRM). In FIG. 3, direction
`of arrow sign depicted in each permanent magnet shows
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`direction of magnetization.
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`In the present embodiment, however, the auxiliary elec-
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`trodes A 104 and B 107 shown in FIG. 1 were not installed.
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`FIG. 4 is a graph showing scraped amounts of the target.
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`As a comparison example, a result for conventional mag—
`netron sputtering device shown in FIG. 6 is shown in FIG.
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`4.
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`Following facts have been found from FIG. 4.
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`(1) By introducing the horizontal magnetic field on the
`surface of the target, the scraped amounts become more
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`uniform than the conventional technique.
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`(2) The arrangement of magnets of FIG. 3 is further more
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`uniform in the scraped amounts than the arrangement of
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`magnets of FIG. 2.
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`6,153,068
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`Embodiment 2)
`In the present embodiment, as the means for introducing
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`magnetic field 101 in the sputtering device shown in FIG. 1,
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`the magnet arrangement shown in FIG. 3 was used, and film
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`qualities of deposit films were investigated for a case that the
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`auxiliary electrodes A 104 and B 107 were not installed and
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`for a case that the auxiliary electrodesA104 and B 107 were
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`installed.
`When the auxiliary electrode B 107 was installed, fre-
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`quency dependency was investigated with respect to radio
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`frequency applied to the auxiliary electrode B 107 from the
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`AC power supply 115. As the frequency, four kinds, 30 kHz,
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`13.56 MHZ, 40 MHZ, and 100 MHZ, were used.
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`As the base body 105, a plurality of single crystal Si
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`wafers (33 mmq)) were placed on the electrode II 106. As the
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`target 103, N-type Si (P-doped) was sputtered using Ar gas
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`so as to deposit Si film on the base body 105. As the film
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`quality of the deposit film, specific resistance was evaluated.
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`FIG. 5 is a graph showing results of measurements of
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`specific resistances together. In FIG. 5, the symbol 0 shows
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`the result in the case that the auxiliary electrode A 104 and
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`A shows the result in the case that radio frequency of 40
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`MHZ was applied to the auxiliary electrode B 107, and the
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`symbol A shows the result in the case that radio frequency
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`of 100 MHZ was applied to the auxiliary electrode B 107.
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`Values of specific resistance shown in the ordinate axis of
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`FIG. 5 are expressed being standardized by a value of
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`specific resistance measured for a base body No. 1.
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`From FIG. 5, following facts have been found.
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`(1) In comparison with the case that the auxiliary electrodes
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`A 104 and B 107 were not installed (shown by symbols
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`0), dispersion of the specific resistances was smaller in
`the cases that the auxiliary electrodes A 104 and B 107
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`were installed (shown by symbols A and A).
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`(2) The dispersion of the specific resistances was further
`smaller in the case that the frequency fc applied to the
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`auxiliary electrode B 107 was sufficiently large relative to
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`the frequency f (1356 MHZ) applied to the target through
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`the electrode I 102 (namely, the case of fc=40 MHZ had
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`smaller dispersion of the specific resistances than the case
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`of fc=100 MHZ).
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`(3) The dispersion of the specific resistances was not
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`improved when the frequency fc applied to the auxiliary
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`electrode B 107 is smaller (380 kHz) than or equal (13.56
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`MHZ) to the frequency f (13.5 6 MHZ) applied to the target
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`103 through the electrode I 102, and the results were
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`similar to the case that the auxiliary electrodes A 104 and
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`B 107 were not installed (shown by symbols 0).
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`(4) In particular, in the case that the frequency fc (1356
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`MHZ) applied to the target 103 through the electrode I 102
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`was equal to the frequency fc (13.56 MHZ) applied to the
`auxiliary electrode B 107, plasma interfered and electric
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`discharge became unstable.
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`10
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`15
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`30
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`35
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`4O
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`45
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`50
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`6
`Thus, it is considered that the frequency fc of the radio
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`frequency power applied to the auxiliary electrode B is
`larger than the frequency f of the radio frequency power
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`applied to the above-described target through the above-
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`described electrode I, film quality of the deposit film can be
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`made uniform.
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`Effects of the Invention
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`As described above, according to the present invention,
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`by introducing magnetic field horizontal to a target’s surface
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`to be sputtered, there is obtained the sputtering device in
`which scraped amounts of the target are uniform.
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`Further, film quality of the deposit film can be uniformed,
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`by providing the auxiliary electrode A in contact with the
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`electrode I and in the area outside the outer peripheral end
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`of the target, and by providing the auxiliary electrode B in
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`the area outside the outer peripheral end of the base body
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`and in a location spaced from the base body and the
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`above-described electrode II. In that case, it is more pref-
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`erable if the frequency fc of the radio frequency power
`applied to the auxiliary electrode B is larger than the
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`frequency f of the radio frequency power applied to the
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`above-described target through the above-described elec-
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`trode I.
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`What is claimed is:
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`1. A sputtering device provided with two electrodes I and
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`II of parallel plate type within a vessel inside which pressure
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`can be reduced, wherein:
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`a target to be sputtered is placed on said electrode I, and
`a base body on which a film is to be deposited is placed
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`on said electrode II, with the target and the base body
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`being opposed to each other;
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`a process gas is introduced into said vessel from a gas
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`supply system;
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`a means for generating a magnetic field with a particular
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`magnetic field oriented horizontal to a sputterable sur-
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`face of the target;
`a radio frequency power is applied to said target through
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`at least said electrode I so as to excite plasma between
`the electrode I and the electrode II;
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`an auxiliary electrode B is supplied; and
`a frequency fc of a radio frequency power is applied to
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`said auxiliary electrode B, said frequency being higher
`than a frequency fof the radio frequency power applied
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`to said target through said electrode I.
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`2. The sputtering device according to claim 1, wherein:
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`said auxiliary electrode B to which said radio frequency
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`power is applied is provided in an area outside an outer
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`peripheral end of said base body and in a position
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`spaced from said base body and said electrode II.
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`*
`*
`>i<
`*
`>l<
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`Page 13 of 13
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`Page 13 of 13
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