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`Samsung Electronics Co., Ltd. v. Demaray LLC
`Samsung Electronic's Exhibit 1028
`Exhibit 1028, Page 1
`
`

`

`pSASLLLLELLLL
`VYLLLELLLO
`0¢l~~~__
`
`
`
`AS22272.LLLELLLLLLLLE
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Patent Application Publication
`
`
`
`
`
`
`
`
`Oct. 10,2002 Sheet 1 of 3
`
`
`
`US 2002/0144889 Al
`
`Ril
`
`
`
`
` cel YATIONLNOOD
`
`
`|ASNVHXa.Be
`
`
`
`NAN
`
`dd
`
`S
`
`BEL
`
`~GiSpa
`
`
`
`C1YO)fOd
`
`Ex. 1028, Page 2
`
`Ex. 1028, Page 2
`
`
`

`

`
`
`
`
`
`
`
`Patent Application Publication Oct. 10,2002 Sheet 2 of 3
`
`
`
`US 2002/0144889 Al
`
`
`°
`'e
`
`—
`
`"
`
`
`|
`somt
`40mT i
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`
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`
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`
`|
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`200 |
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`450. oS
`
`
`3
`4 45 5
`4 45 5
`2
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`
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`
`
`
`
`
`RF Power (kW)
`
`
`
`APSE SD
`
`
`~~ 70.
`
`
`
`
`
`1
`
`|
`
`2
`
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`
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`
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`
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`
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`
`_a- NewBurn-in .
`i
`
`
`~a- Old Burn-in
`
`
`
`
`
`X27303 Finish Bum-in with NewProcess
`|
`3.0; A \
`
`
`
`
`
`
`Finish Burn-in with Old Process
`!
`DN
`
`/ a |
`af
`5 Fee
`|
`!
`
`
`
`|
`or
`
`
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`
`
`35;
`
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`2.0,
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`1.5
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`
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`
`5
`2
`4
`3
`
`
`
`
`
`Target Burn-in kW-hrs
`
`
`
`6
`
`
`
`7
`
`8
`
`
`
`Ex. 1028, Page 3
`
`.
`
`
`Cu
`
`,
`
`Resor
`
`
`fut
`(ohm-um)
`
`ro
`
`Ex. 1028, Page 3
`
`

`

`
`
`
`
`
`
`
`Patent Application Publication Oct. 10,2002 Sheet 3 of 3
`
`
`
`US 2002/0144889 Al
`
` @ FWHM- New Process
`
`
`
`
`
`
`a@ FWHM- Old Process
`
`
`
`
`t |I
`
`iA.
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`
`
`
`
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`
`
`
`Finish Burn-in with Old Process
`
`
`
`
`
`
`
`+
`
`/
`*
`.
`.
`
`
`FW!
`
`ot Cu (Akt)
`
`
`
`
`peak
`
`
`
`6.0
`
`
`
`50
`
`
`40
`
`
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`
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`
`Finish Burn-in with New Process
`
`
`
`
`
`
`
`0)
`
`
`
`i
`
`2
`
`3
`
`
`
`
`
`Target Burn-in kW-hrs
`
`4
`
`FiG, +
`
`6
`
`
`7
`
`
`
`
`
`5
`
`
`Ex. 1028, Page 4
`
`Ex. 1028, Page 4
`
`

`

`
`
`US 2002/0144889 Al
`
`
`
`Oct. 10, 2002
`
`
`
`BURN-IN PROCESS FOR HIGH DENSITY PLASMA
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`
`PVD CHAMBER
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`
`
`FIELD OF THE INVENTION
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`[0001] The present invention relates generally to semicon-
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`ductor device manufacturing, and more particularly to a
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`burn-in process employed in an high density plasma physi-
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`cal vapor deposition (HDPPVD) chamber.
`BACKGROUND OF THE INVENTION
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`[0002] FIG. 1 is a side diagrammatic illustration, in sec-
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`tion, of the pertinent portions of a conventional high density
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`plasma (HDP) sputtering or physical vapor deposition
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`(PVD) chamber 100. The sputtering chamber 100 contains a
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`coil 102 which is operatively coupled to a first RF power
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`supply 104 via one or more feedthroughs 105. The coil 102
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`may comprisea plurality of coils, a single turn coil, a single
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`turn material strip, or any other similar configuration. The
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`coil 102 is positioned along the inner surface of the sput-
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`tering chamber 100, between a sputtering target 106 and a
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`substrate pedestal 108. Both the coil 102 and the target 106
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`are formed from the to-be-deposited material (e.g., copper,
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`aluminum,titanium, tantalum, etc.).
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`[0003] The substrate pedestal 108 is positioned in the
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`lower portion of the sputtering chamber 100 and typically
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`comprises a pedestal heater (not shown) for elevating the
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`temperature of a semiconductor wafer or other substrate
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`supported by the substrate pedestal 108 during processing
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`within the sputtering chamber 100. The sputtering target 106
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`is mounted to a water cooled adapter 110 in the upper
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`portion of the sputtering chamber 100 so as to face the
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`substrate receiving surface of the substrate pedestal 108. A
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`cooling system 112 is coupled to the adapter 110 and
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`delivers cooling fluid (e.g., water) thereto.
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`[0004] The sputtering chamber 100 generally includes a
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`vacuum chamberenclosure wall 114 havingat least one gas
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`inlet 116 coupled to a gas source 118 and having an exhaust
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`outlet 120 coupled to an exhaust pump 122 (e.g., a cry-
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`opumpor a cryoturbo pump). The gas source 118 typically
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`comprises a plurality of processing gas sources 118a, 1185
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`such as a source of argon, helium and/or nitrogen. Other
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`processing gases may be employedif desired.
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`[0005] Aremovable shield 124 that circumferentially sur-
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`rounds the coil 102, the target 106 and the substrate pedestal
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`108 is provided within the sputtering chamber 100. The
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`shield 124 may be removed for cleaning during chamber
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`maintenance, and the adapter 110 is coupled to the shield
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`124 (as shown). The shield 124 also supports the coil 102 via
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`a plurality of cups 126a-b attached to, but electrically
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`isolated from the shield 124, and via a plurality of pins
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`128a-b coupled to both the cups 126a-b and the coil 102.
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`The coil 102 is supported by resting the coil 102 on the pins
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`128a-b which are coupled to the cups 126a-b. The cups
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`126a-b and the pins 128a-b comprise the same material as
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`the coil 102 and the target 106 (e.g., copper) and are
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`electrically insulated from the shield 124 via a plurality of
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`insulating regions 129a-b (e.g., a plurality of ceramic
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`regions). The sputtering chamber 100 also includes a plu-
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`rality of bake-out lamps 130 located between the shield 124
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`and the chamber enclosure wall 114, for baking-out the
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`sputtering chamber 100.
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`[0006] The sputtering target 106 and the substrate pedestal
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`108 are electrically isolated from the shield 124. The shield
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`124 may be grounded so that a negative voltage (with
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`respect
`to grounded shield 124) may be applied to the
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`sputtering target 106 via a first DC power supply 132
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`coupled between the target 106 and ground, or may be
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`floated or biased via a second DC power supply 133 coupled
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`to the shield 124. Additionally, a negative bias may be
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`applied to the substrate pedestal 108 via a second RF power
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`supply 134 coupled between the pedestal 108 and ground. A
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`controller 136 is operatively coupled to the first RF power
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`supply 104, the first DC power supply 132, the second DC
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`powersupply 133, the second RF powersupply 134,the gas
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`source 118 and the exhaust pump 122. The controller 136
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`includes computer program code adapted to control various
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`operating parameters of the chamber 100 including the
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`powerlevels provided by the power supplies 104, 132, 133,
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`134 and the pressure level in the chamber 100.
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`[0007]
`To perform deposition within the sputtering cham-
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`ber 100, a substrate 138 (e.g., a semiconductor wafer, a flat
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`panel display, etc.) is loaded into the sputtering chamber
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`100, is placed on the substrate pedestal 108 and is securely
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`held thereto via a clamp ring 140. An inert gas such as argon
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`then is flowed from the gas source 118 into the high density
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`plasma sputtering chamber 100 and the first DC power
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`supply 132 biases the sputtering target 106 negatively with
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`respect to the substrate pedestal 108 and the shield 124. In
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`response to the negative bias, argon gas atoms ionize and
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`form a plasma within the high density plasma sputtering
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`chamber 100. An RF bias preferably is applied to the coil
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`102 via the first RF power supply 104 to increase the density
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`of ionized argon gas atoms within the plasma and to ionize
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`target atoms sputtered from the target 106 (as described
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`below).
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`[0008] Because argon ions have a positive charge, argon
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`ions within the plasmaare attracted to the negatively biased
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`sputtering target 106 andstrike the sputtering target 106 with
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`sufficient energy to sputter target atoms from the target 106.
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`The RF powerapplied to the coil 102 increases the ioniza-
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`tion of the argon atoms, and,
`in combination with the
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`coupling of the coil power to the region of argon and
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`sputtered target atoms, results in ionization of at least a
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`substantial portion of the sputtered target atoms. The ion-
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`ized, sputtered target atoms travel to and deposit on the
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`substrate 138 so as to form over time a continuous target
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`material film 142 thereon. Because the sputtered target
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`atomsare ionized bythe coil 102, the target atomsstrike the
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`substrate 138 with increased directionality under the influ-
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`ence of the electric field applied between the target 106 and
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`the substrate pedestal 108 (e.g., by the first DC power supply
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`132). The second RF power supply 134 may be employed to
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`apply a negative bias to the substrate pedestal 108 relative to
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`both the sputtering target 106 and to shield 124 to further
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`attract sputtered target atoms to the substrate 138 during
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`deposition.
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`[0009]
`In addition to target atoms, coil atoms are sputtered
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`from the coil 102 during deposition and deposit on the
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`substrate 138. Because of the coil’s proximity to the wafer’s
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`edge the sputtered coil atoms predominantly coat the sub-
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`strate 138 near its edges and, wheretheflat target atoms tend
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`to deposit a center thick layer, result in overall uniformity of
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`the thickness of the film 142 deposited on the substrate 138.
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`Following deposition, the flow of gas to the high density
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`Ex. 1028, Page 5
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`Ex. 1028, Page 5
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`

`

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`US 2002/0144889 Al
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`Oct. 10, 2002
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`plasma sputtering chamber 100 is halted, all biases (e.g.,
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`target, pedestal and coil) are terminated, and the substrate
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`138 is removed from the high density plasma sputtering
`chamber 100.
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`[0010] Occasionally the sputtering chamber 100 must be
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`vented to the atmosphere to permit cleaning or routine
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`maintenance and/or replacementof the sputtering target 106
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`and the coil 102. After the chamber 100 has been exposed to
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`atmosphere, and before proceeding with deposition, decon-
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`tamination processes must be performed to place the cham-
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`ber in a suitable condition for deposition processing. One
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`decontamination procedure is known as “bake-out”. During
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`the chamber 100 is maintained at an elevated
`bake-out,
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`temperature (e.g., via the bake-out
`lamps 130)
`for an
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`extended period of time to de-sorb contaminants such as
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`moisture or other gases from the chamber walls and other
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`{0011] Another decontamination process is referred to as
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`“burn-in” and is applied to the sputtering target 106 and to
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`the coil 102. During burn-in the respective powersignals are
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`applied to the target 106 and to the coil 102, and contami-
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`nants such as surface oxides, or trace metals introduced into
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`the target or coil during manufacturing, are removed by
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`sputtering atoms or molecules from the target and coil.
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`Typically, burn-in is carried out
`intermittently, with a
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`sequence of substrates present
`in the chamber 100 for
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`monitoring purposes. That is, a substrate is loaded onto the
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`pedestal 108, a burn-in cycle is performed, and the substrate
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`is removed and replaced with another substrate, whereupon
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`another burn-in cycle is performed.
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`[0012] One application that has been proposed for HDP
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`sputtering chambers is deposition of copper as a seed layer
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`for electroplating. To obtain suitable Cu seed layer quality,
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`it has been foundto be desirable to provide active cooling of
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`the substrate during the seed layer deposition. In order to
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`provide active cooling, the conventional clamp ring (e.g.,
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`clamp ring 140) has been replaced with a low temperature
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`the
`biasable electrostatic chuck (LTBESC). However,
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`LTBESC has proven to be susceptible to malfunction or
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`permanentfailure resulting from contamination from copper
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`evaporation from the coil that occurs during burn-in. To
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`prevent chuck malfunction or permanent failure, the con-
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`ventional burn-in process may be modified to reduce copper
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`evaporation from the coil by reducing the duty cycle of the
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`RF powersignal applied to the coil. Also, to avoid substrate
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`breakage, the dwell time in the chamber for each monitor
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`substrate employed during burn-in may be reduced so that
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`the total number of substrates used for monitoring was
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`increased. However, these changes may result in a substan-
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`tial increase in the total elapsed time required for burn-in,
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`and a corresponding increase in the down-time for the
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`sputtering chamber when maintenance is performed.
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`[0013]
`It would be desirable to provide a burn-in process
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`that can be performed more rapidly, but without compro-
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`mising the functioning of the LTBESC.
`SUMMARYOF THE INVENTION
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`[0014] An aspect of the invention provides a method of
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`performing a burn-in process wherein contaminants are
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`removed from a coil and a sputtering target installed in a
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`high density plasma PVD chamber. The inventive method
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`includes applying respective power signals to the coil and
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`the sputtering target while maintaining a pressure level in the
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`chamber of less than 40 mT.
`In one embodiment,
`the
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`pressure level in the chamber is maintained at less than 25
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`mT, and in another embodimentat substantially 10 mT.
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`[0015] The present inventors have discovered that a burn-
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`in process performed at a lower pressure is more efficient
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`than a conventional burn-in process (e.g.,
`typically per-
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`formed at a pressure of at least 40 mT or higher), thereby
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`permitting the total elapsed time for burn-in to be decreased
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`and reducing overall down-time required for chamber main-
`tenance.
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`features and advantages of the
`[0016] Other objects,
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`invention will become more fully apparent from the follow-
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`ing detailed description of the exemplary embodiments, the
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`appended claims and the accompanying drawings.
`BRIEF DESCRIPTION OF THE DRAWINGS
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`[0017] FIG. 1 is a side diagrammatic illustration, in sec-
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`tion, of components of a conventional high density plasma
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`sputtering chamber;
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`[0018] FIG.2 isa graph of coil voltage data obtained from
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`coils that were burned-in using processes that varied in
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`terms of chamberpressure, powerlevel applied to target, and
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`powerlevel applied to coil;
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`[0019] FIG.3 isa graph of copperresistivity data gathered
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`from wafers processed according to conventional and inven-
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`tive burn-in processes; and
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`[0020] FIG. 4 is a graph of data indicative of full-width-
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`half-max (FWHM)readings for the Cu (111) peak obtained
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`from monitor wafers processed in accordance with conven-
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`tional and inventive burn-in processes.
`DETAILED DESCRIPTION OF PREFERRED
`
`
`EMBODIMENTS
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`[0021] The present inventors carried out a series of experi-
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`ments to determine the effects of process pressure, level of
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`DC power applied to the target, and level of RF power
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`applied to the coil on the efficiency of burn-in processes.
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`These experiments were performed using an HDPsputtering
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`chamberlike that illustrated in FIG.1, except that, as noted
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`before, a LTBESC (not shown) wasinstalled in placeof the
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`clamp ring 140. The coil voltage was taken as an indicator
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`of the efficiency of the burn-in. In the experimental burn-in
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`processes, the chamberpressure was varied in a range of 60
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`mT to 10 mT; the DC powersupplied to the target was set
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`at 1 kW, 1.5 kW and 2 kW;and the RF powerapplied to the
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`coil was varied in a range of 2-5 kW.
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`[0022] FIG. 2 presents data indicating the coil voltages
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`obtained from the respective experimental burn-in pro-
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`cesses. The left-hand third of the graph of FIG.2 indicates
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`results obtained from burn-in processes carried out with a
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`DC powerlevel applied to the target of 1 kW. The middle
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`third indicates results obtained with a DC powerlevel of 1.5
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`kW. The mnght-hand third of the graph indicates results
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`obtained with the DC powerlevel at 2 kW.
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`[0023] The results presented in FIG. 2 indicate that low-
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`ering the process pressure of the sputtering chamber, raising
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`the DC powerlevel applied to the target and raising the RF
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`powerlevel applied to the coil all generally have a positive
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`effect on coil voltage. Of these three factors, lowering the
`
`Ex. 1028, Page 6
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`Ex. 1028, Page 6
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`

`

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`US 2002/0144889 Al
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`Oct. 10, 2002
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`monitor wafers for the old recipe burn-in process. Once
`more it will be observed that the desired benchmark was
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`achieved with a burn-in corresponding to 3 kW-hr of DC
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`powerappliedto the target with the new recipe, as compared
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`to 5 kW-hr being required to achieve this benchmark using
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`the old recipe process.
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`[0027] The monitor wafers were also examined using
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`secondary ion mass spectroscopy (SIMS) and it was deter-
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`mined that a 3 kW-hr target burn-in using the new recipe
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`performed satisfactorily in terms of eliminating trace metal
`contaminants.
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`[0028] Based on these results, it was determined that a
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`burnin process using the new recipe could be satisfactorily
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`terminated upon 3 kW-hr of DC powerhaving been applied
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`to the target. This is in contrast to the conventional process
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`using the old recipe, in which a total of 5 kW-hr of DC
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`power was applied to the target. The total elapsed time for
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`the burn-in process using the new recipe was about 6 hours,
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`as compared to 10 hoursfor the burn-in process using the old
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`recipe. This represents a substantial
`reduction in time
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`required for burn-in, and a corresponding reduction in the
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`down-time required for maintenance of the HDP sputtering
`chamber.
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`process pressure is the most significant in increasing coil
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`voltage (e.g.,
`increase coil voltage and thus evidence
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`improved burn-in efficiency). Moreover,
`there are con-
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`straints upon increasing the DC and RF powerlevels applied
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`to the target and coil, respectively. As to increasing the RF
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`powerlevel applied to the coil, at increased levels the coil
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`temperature is increased, leading to coil evaporation. As
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`noted before, coil evaporation may interfere with the func-
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`tioning of the LTBESC. Onthe other hand, increased DC
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`power applied to the target may lead to net deposition from
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`the target on the coil. Deposition from the target to the coil
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`may generate particles, and may trap contaminants on the
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`coil. However, lowering the pressure within the sputtering
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`chamber does not suffer from these adverse effects, and
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`therefore was consideredto be the best way of improving the
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`efficiency of the burn-in process.
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`[0024] With these factors in mind, the present inventors
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`determined that an optimal recipe for the burn-in process
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`called for 1 kW of DC powerapplied to the target, 3 kW of
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`RF powerapplied to the coil, and a process pressure of 10
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`mT. This is in contrast to a conventional burn-in recipe of 1
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`kW-DC/3 kW-RF/40 mT. The duty cycle in both cases was
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`1:1 on:off. The improved efficiency of the lower-pressure
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`recipe as compared to the conventionalrecipe is indicated by
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`comparing data points 201 and 202 in FIG. 2. Data point
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`201 indicates that a coil voltage of 245 V was produced by
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`[0029] The foregoing description discloses only exem-
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`the 1 kW-DC/3 kW-RF/10 mT recipe (the “new recipe”),
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`plary embodiments of the invention; modifications of the
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`whereas data point 202 indicates that a coil voltage of 170
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`above disclosed apparatus and method whichfall within the
`V was produced by the 1 kW-DC/3 kW-RF/40 mTrecipe
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`scope of the invention will be readily apparent to those of
`(the “old recipe”). As stated previously, a higher coil voltage
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`ordinary skill in the art. For example, although the invention
`is indicative of a more effective burn-in process.
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`has been described in connection with burn-in of a copper
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`[0025] To confirm the improved effectiveness of the new
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`target and copper coil, it is also applicable to burn-in of
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`recipe relative to the old recipe, further experiments were
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`targets and coils for depositing other metals, such as Ti, W,
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`undertaken. In one set of experimentsthe resistivities of Cu
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`and Ta. Moreover, the HDP chamberto which the invention
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`films deposited on monitoring wafers were compared for
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`is applicable need not be equipped exactly as described
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`burn-in processes using the old and new recipes. Results of
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`herein. Although the invention is particularly advantageous
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`this experiment are presented in FIG. 3. In FIG.3, curve
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`when used in a HDP sputtering chamber which uses an
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`203 plots resistivity data for Cu layers deposited during the
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`LTBESC, an LTBESC need not necessarily be employed.
`new recipe burn-in process. Curve 204 plots resistivity data
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`for Cu layers deposited during an old recipe burn-in process.
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`[0030] Also, althoughit is preferred to perform the burn-in
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`In the case of both processes, resistivity decreases with
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`process at a chamberpressure of substantially 10 mT,it is
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`increased burn-in duration, but after an initial period lower
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`within the scope of the invention to employ any pressure
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`resistivity levels are achieved with the new recipe process.
`level that is less than the conventional level of 40 mT.
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`Taking a 2.5 ohm-cm deposited copperfilm as a benchmark
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`Further, the inventive burn-in processes described herein
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`indicative of a satisfactory burn-in, it will be noted that this
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`may be performed within an HDP sputtering chamber during
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`level of resistivity is achieved with the new recipe burn-in
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`and/or after a bake out process is performed within the
`process after applyingatotal of 3 kW-hr of DC powerto the
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`chamber(e.g., any conventional bake-out procedure used to
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`target. With a 1:1 on:off duty cycle, this amount of total
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`bake out the walls, shield,
`target, pedestal or any other
`applied powerresults in about a six-hour elapsed time for
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`chamber surface). In accordance with at least one embodi-
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`burn-in for a 1 kW level of DC power. On the other hand,
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`mentof the invention, an inventive HDPsputtering chamber
`with the old recipe process, the benchmark is not achieved
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`may be provided based on the conventional HDP sputtering
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`until a total of 5 kW-hr has been applied to the target which
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`chamber 100 of FIG. 1 (or based on any other HDP
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`requires about 10 hours.
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`sputtering chamber such as one that employs a LTBESC) by
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`[0026]
`In another confirming experiment, the texture of
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`providing the controller 136 with computer program code
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`the Cu thin films deposited on monitor wafers was compared
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`adapted to perform a burn-in process by applying respective
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`for the new recipe and old recipe processes. The full width
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`powersignals to the coil and the target while maintaining the
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`half max (FWHM)of the Cu (111) peak was detected for
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`pressure level in the chamberat less than 40 mT.
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`each deposited copperfilm, and a benchmark of 3.8 or below
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`[0031] Accordingly, while the present invention has been
`was considered to indicate a satisfactory burn-in. FIG. 4
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`presents the results of this experiment.
`In FIG. 4 the
`disclosed in connection with a preferred embodiment
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`diamond-shaped data points represent FWHM-Cu (111)
`thereof, it should be understood that other embodiments may
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`peak figures for monitor wafers for the new recipe burn-in
`fall within the spirit and scope of the invention, as defined
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`process. The square data points represent the results for
`by the following claims.
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`Ex. 1028, Page 7
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`Ex. 1028, Page 7
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`US 2002/0144889 Al
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`Oct. 10, 2002
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`The invention claimedis:
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`1. A method of performing a burn-in process wherein
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`contaminants are removed from a coil and a sputtering target
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`installed in a high density plasma PVD chamber, the method
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`comprising applying respective powersignals to the coil and
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`the sputtering target while maintaining a pressure level in the
`chamberof less than 40 mT.
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`2. The method of claim 1, wherein the pressure level in the
`chamber is maintained at less than 25 mT.
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`3. The method of claim 2, wherein the pressure level in the
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`chamber is maintained at substantially 10 mT.
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`4. The method of claim 3, wherein the power signal
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`applied to the sputtering target is a DC signal at a level of
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`substantially 1 kW and the power signal applied to the coil
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`is an RF signal at a level of substantially 3 kW.
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`5. The method of claim 4, wherein the burn-in processis
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`terminated upon substantially 3 kW-hr of power having been
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`applied to the sputtering target.
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`6. The method of claim 1, wherein the sputtering target
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`and the coil are formed of copper.
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`7. An apparatus comprising:
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`a high density plasma PVD chamber having:
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`a target;
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`a first signal source coupled to the target;
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`a coil;
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`a second signal source coupled to the coil;
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`a substrate pedestal; and
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`an exhaust system adapted to control a pressure level in
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`the chamber; and
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`a controller coupled to the first signal source, the second
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`signal source, and the exhaust system, the controller
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`having computer program code adapted to perform a
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`burn-in process by applying respective powersignals to
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`the coil and the target while maintaining the pressure
`level in the chamberat less than 40 mT.
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`8. The apparatus of claim 7, wherein the computer pro-
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`gram code is adapted to maintain the pressure level in the
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`chamberat less than 25 mT during the burn-in process.
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`9. The apparatus of claim 8, wherein the computer pro-
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`gram code is adapted to maintain the pressure level in the
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`chamberat substantially 10 mT during the burn-in process.
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`10. The apparatus of claim 9, wherein the computer
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`program code is adapted to control the first and second
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`signal sources such that a DC powersignal is applied to the
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`target at a level of substantially 1 kW and an RF power
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`signal is applied to the coil at a level of substantially 3 kW.
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`11. The apparatus of claim 10, wherein the computer
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`program code is adapted to terminate the burn-in process
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`upon substantially 3 kW-hr of power having been applied to
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`the target.
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`12. The apparatus of claim 7, wherein the target and the
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`coil are formed of copper.
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`13. A method of decontaminating a high density plasma
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`PVD chamber, comprising the steps of:
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`baking-out the chamber by applying heat to the chamber
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`to desorb contaminants from a chamber surface; and
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`performing a burn-in process to remove contaminants
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`from a coil and a sputtering target installed in the
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`chamber by applying respective power signals to the
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`coil and the sputtering target while maintaining a
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`pressure level in the