Samsung Electronics Co., Ltd. v. Demaray LLC
`Samsung Electronic's Exhibit 1048
`Exhibit 1048, Page 1
`
`

`

`P.J. Kelly et al./Surface and Coatings Technology86 -87 ( 1996) 28-32
`
`29
`
`Rf. sputtering is generally considered too slow and
`complex a process for large scale commercial applica-
`tions [7,8].
`the pulsed magnetron sputtering process
`However,
`(PMS)offers the potential to overcome the problems
`encountered when operating in the reactive sputtering
`mode with the CFUBMSsystem. Initial studies have
`indicated that pulsing the magnetron discharge at
`medium frequencies
`(10-200kHz), when depositing
`highly insulating materials, can significantly reduce the
`formation of arcs and, consequently reduce the number
`of defects in the resulting film [6-11]. For example,
`Schiller [9,10] found that during the reactive sputtering
`of Al,O3, raising the pulse rate from 10 to 50 kHz
`reduced the defect density of the coating by several
`orders of magnitude. Furthermore, deposition rates of
`4-5 nms~! were achieved, which compares with less
`that
`1 nms~* for RF sputtering of Al,O3. This rate
`amounted to about 60% of the rate achieved by Schiller
`for
`the non-reactive sputtering of pure aluminium.
`Pulsing was also found to stabilise the discharge. This
`allowed Frach [7]
`to deposit virtually defect-free
`Al,O3 coatings up to 50 wm thick.
`If a single magnetron discharge is pulsed, then the
`system is described as unipolar pulsed sputtering. In this
`situation, the pulse-on time is limited so that the charging
`of the insulating layers does reach the point where
`breakdown and, therefore, arcing occurs. The discharge
`is dissipated during the pulse-off time through the
`plasma. If two magnetrons are connected to the same
`pulse supply then the configuration is described as
`bipolar pulsed sputtering. Each magnetron source then
`alternately acts as an anode and a cathodeof a discharge.
`The periodic pole changing promotes discharge of the
`insulating layers, hence preventing arcing.
`The high rate deposition of defect-free ceramic coat-
`ings onto complex components would be a commercially
`attractive process. In view of this, the PMS process is
`being increasingly studied. This paper, therefore, reports
`on work carried out at Salford University to investigate
`the deposition of alumina coatings in a closed-field
`unbalanced magnetron system, utilising the PMS
`process.
`
`2. Experimental
`
`Alumina coatings were deposited by reactive magnet-
`ron sputtering in a Teer Coatings UDP 450 rig. The rig
`is equipped with two 300 x 100 mm vertically opposed
`unbalanced magnetrons installed in a closed-field con-
`figuration. The aluminium sputter targets were 99.5%
`pure and were also obtained from Teer Coatings.
`Coatings were deposited onto silicon wafers, polished
`aluminium SEM pin stubs and ground stainless steel
`coupons.
`The reactive sputtering process was controlled using
`
`spectral line monitoring [12-14]. The optical emission
`monitor (OEM) was tuned to the 396 nm line in the
`aluminium emission spectrum. The target current was
`ramped up and pure Alfilms were deposited for 2 min.
`The OEMsignal at this point was taken as the “100%”
`metal signal. The reactive gas was then allowed into the
`chamber until the OEMsignalfell to a pre-determined
`proportion of the initial 100% metal signal. The value
`of the “turn-down”signal was maintained by the feed-
`back loop throughout the remainder of the deposition
`run. After each reactive deposition,
`the targets were
`sputter cleaned until
`the OEM signal returned to its
`initial value.
`The coatings were deposited using, either a d.c. power
`supply in series with a fixed 20kHz pulse unit, or a
`supply with a variable frequency in the range 0.05 Hz
`to 33 kHz (for comparison purposes, coatings were also
`deposited by reactive d.c. sputtering, without pulsing the
`discharge). The 20 kHz unit was an Advanced Energy
`SPARC-LEunit, which was connected in series with the
`existing Advanced Energy MDX magnetron driver [8].
`The magnitude of the positive pulse is fixed at about
`10% of the magnitudeof the negative pulse. The variable
`frequency supply was a Magtron unit [15]. This unit is
`more sophisticated than the SPARC-LE.It can be used
`in unipolar or bipolar mode and the pulse-on and pulse-
`off times can be varied independently. Only the unipolar
`configuration was used in this investigation.
`All
`the coatings were deposited at a substrate-
`to-target separation of 110mm and a pressure of
`1.25 mTorr. Target current, substrate bias and OEM
`turn-down signal were varied. The run conditions are
`summarised in Table 1. The coatings deposited on silicon
`wafers were fractured to allow the coating structure to
`be examined in the SEM. Thickness measurements were
`taken from SEM micrographs of the fracture sections.
`Knoop microhardness measurements were also made of
`these coatings. Measurements were taken at three appro-
`priate loads. The results were then extrapolated to zero
`load to remove any influence of the substrate material
`on the apparent hardness of the coatings. The composi-
`tion of the coatings, deposited on polished pin stubs,
`was determined using a JEOL JXA-50A microanalyser,
`equipped with WDAX. The accuracy of this machine,
`as quoted by the manufacturer, is between 1 and 5 at.%.
`Pin-on-disc wear tests were carried out on selected
`specimens, deposited onto ground stainless steel cou-
`pons. The “pin” was a 6.35 mm diameter hardened steel
`ball. The normal load was 3 N; the sliding speed 44
`mmin™*; and the sliding distance 61.6 m. Profilometry
`tests and SEM examination were carried out on the
`specimensafter testing. Someinitial results are presented.
`
`3. Results
`
`The deposition rates, microhardnesses and composi-
`tions of the coatings are listed in Table 1. As expected,
`
`Ex. 1048, Page 2
`
`Ex. 1048, Page 2
`
`

`

`30
`
`PJ, Kelly et al.{Surface and Coatings Technology 86-87 ( 1996) 28-32
`
`Table 1
`Run conditions and properties of aluminium oxide coatings depositedby d.c, and pulsed magnetron sputtering
`
`Run
`Target
`Substrate
`Turn down
`Thickness
`Dep. rate
`Hk
`AIO
`Power
`
`no.
`Current (A)
`bias (V)
`signal (%)
`(ym)
`(um min7*)
`(kg mm7?)
`(at.%)
`supply
`
`1
`2
`3
`4
`5
`6
`7
`8
`9
`10
`il
`12
`13
`
`6
`6
`6
`6
`6
`6
`8
`6
`6
`6
`3
`3
`3
`
`~— 50 rf
`— 50 rf
`~ 50 rf
`~30 rf
`~30 rf
`— 100 rf
`—50 rf
`self-bias (—19)
`—50 de
`—50 de
`— 100 de
`—50 de
`— 30 de
`
`60
`50
`50
`30
`30
`15
`15
`25
`20
`20
`15
`20
`15
`
`13.9
`17
`5.3
`31
`2.0
`33
`3.8
`40.0
`13.0
`10.0
`49
`8.1
`5.0
`
`0.52
`0.28
`0.19
`0.11
`0.07
`0,07
`0.07
`0.31
`0.13
`0.18
`0.06
`0.07
`0.06
`
`90
`210
`320
`2650
`1240
`1180
`2480
`270
`1940
`1710
`1020
`1510
`2010
`
`51/49
`51/49
`58/42
`45/55
`44/56
`37/63
`41/59
`54/46
`42/58
`43/57
`41/59
`40/60
`37/63
`
`d.c. only
`d.c. only
`d.c.+SPARC-LE
`d.c.+SPARC-LE
`d.c.+SPARC-LE
`d.ic.+SPARC-LE
`d.c.+SPARC-LE
`Magtron 15.4 kHz
`d.c.+ SPARC-LE
`Magtron (15.4 kHz)
`Magtron(15.4 kHz)
`Magtron (25 kHz)
`Magtron (25 kHz)
`
`the d.c. reactive sputtering of aluminium oxide coatings
`proved extremely difficult. Arcing took place from the
`target throughout the runs, and the process was highly
`unstable, even at turn-down signals of 60% of the pure
`metal signal, i.c., relatively low levels of target poisoning.
`The structure of one of these coatings (run no. 1) is
`shown in Fig.1. As can be seen,
`the coating has a
`granular, porous structure. Reference to Table 1 indicates
`a
`sub-stoichiometric
`composition
`and
`vyery
`low
`microhardness.
`By contrast, when operating with the SPARC-LE
`units the process was very stable, with few arc events at
`the target. This was found to be the case, even at turn-
`down signals of 15%,
`ie., sputtering from a heavily
`poisoned target. Figs,2 and 3 show SEM micrographs
`of the fracture sections of coatings 7 and9, respectively.
`Both coatings are fully dense with no discernible struc-
`tural aspects on the fracture surface, Also, both coatings
`remained well adhered to the substrate after fracture.
`
`The composition of these coatings is very close to
`
`Fig. £, SEM micrographoffracture section of aluminium oxide coating
`number 1, deposited by d.c, magnetron sputtering onto silicon wafer,
`
`
`
`Fig. 2. SEM micrograph offracture section of aluminium oxide coating
`number 7, deposited by d.c. magnetron sputtering with SPARC-LE
`pulse unit attachment. The substrate is a silicon wafer.
`
`2,
`
`SONATS SOURERIS TR
`
`
`onsen
`
`|
`
`Fig. 3. SEM micrographoffracture section of aluminium oxide coating
`number 9, deposited by d.c. magnetron sputtering with SPARC-LE
`pulse unit attachment, The substrateis a silicon wafer.
`
`Ex. 1048, Page 3
`
`

`

`P.J. Kelly et al./Surface and Coatings Technology 86-87 ( 1996) 28-32
`
`31
`
`stoichiometric Al,O;. Both have high microhardness
`values (2480 and 1940 kg mm ~*, respectively). However,
`the deposition rate for run 9 was nearly twice that of
`run 7, despite the fact that the target current was lower.
`This, presumably, reflects the greater degree of target
`poisoning (i.e., the lower OEM signal) during run 7.
`It proved difficult to optimize the performance of the
`Magtron unit. When operating at a target current of 6
`A and a pulse frequency of 15.4 kHz, arcing occurred at
`the target throughout the run, with the frequency of arcs
`increasing with run time. The supply operated most
`successfully when delivering a target current of 3 A, at
`a frequency of 20 kHz with identical pulse-on and pulse-
`off times. Fig.4 shows an SEM micrograph of the
`fracture section of coating 13, deposited using the
`Magtron supply. Again, the coating has a fully dense
`structure and good coating-to-substrate adhesion. The
`microhardness, deposition rate and composition of this
`coating are very similar to coating 7, deposited using
`the SPARC-LE unit. However, coating 7 was deposited
`at a target current of 8 A, whereas, coating 13 was
`deposited at a target current of 3 A. Thesimilarity in
`deposition rates, despite the significant difference in
`target powers between these two coatings cannot be
`explained at
`this stage, particularly as both coatings
`were deposited at the same turn-downsignal.
`Pin-on-disc tests were carried out on a number of
`selected specimens, as described earlier. The results of
`these tests are listed in Table 2. Profilometry measure-
`ments were made of the wear tracks for coatings 7, 8
`and 13 and, from this, wear volumes were calculated.
`Fig. 5 shows a SEM micrographof the surfaceof coating
`8, showing part of the wear track. The wear track for
`coating 9 was within the original surface roughness and,
`therefore, a wear volumecould notbe calculated for this
`specimen. A section of the wear track on the surface of
`coating 9 is shown in Fig. 6. For coating 12, material
`
`
`
`Fig. 4. SEM micrographoffracture section of aluminium oxide coating
`number 13, deposited by pulsed magnetron sputtering onto silicon
`wafer.
`
`Table 2
`Results of pin-on-disc tests on selected aluminium oxide coatings
`deposited on stainless steel coupons
`
`Coating number
`
`7
`
`0.25
`0,83
`
`8
`
`9
`
`12
`
`13
`
`0.1
`0.33
`
`0.26
`0.87
`
`0.2
`0.63
`
`0.26
`0.87
`
`LO2QE-3
`
`O41
`
`—
`
`-
`
`1.23B-3
`
`Frictional force (N)
`Steady state coef,
`offriction (1s)
`Wear volume (mm’)
`
`
`
`
`Fig. 5. SEM micrograph ofsurface of aluminium oxide coating number
`8, showingpart of pin-on-disc wear track,
`
`Fig. 6. SEM micrograph of surface of aluminium oxide coating number
`9, showing part of pin-on-disc wear track.
`
`transfer occurred from the steel ball to the coating
`surface. SEM examination of the wear track showed
`that only transferred material was present, and no wear
`of the coating was observed. Figs.7 and 8 are SEM
`micrographs of the wear track region for coating 12,in
`which transferred material can clearly be seen. Fig.7
`also demonstrates how closely the topography of the
`coating surface matches the topographyof the substrate,
`
`Ex. 1048, Page 4
`
`

`

`32
`
`Fig. 7. SEM micrographof surface of aluminium oxide coating number
`
`pure aluminium films using the SPARC-LE attachment
`and for d.c. sputtering alone under otherwise identical
`conditions.
`Both of the pulse units investigated were stable in
`operation (once optimized), with very few arcs being
`observed at the target. Both allowed control over the
`reactive sputtering process to be established. Thus, the
`composition of the coating and, therefore, its properties,
`could be controlled.
`
`5. Conclusions
`
`This investigation has demonstrated that fully dense
`coatings of alumina can be deposited in a CFUBMS
`system at rates of about 40% of that obtained for the
`d.c, sputtering of aluminium. The pulsed magnetron
`sputtering process is a major developmentin the reactive
`sputtering field. The prevention of arcs at the target
`provides stability to the reactive sputtering process. This,
`in turn, permits the coating composition and properties
`to be controlled. The ability to deposit defect-free oxide
`coatings at high rates offers the potential to improve the
`performance and extend the range of applications of
`these coatings.
`
`P.J, Kellyet al./Surface and Coatings Technology 86-87 ( 1996) 28-32
`12, showing part of pin-on-disc wear track and topographicaldetail.
`
`Fig. 8. SEM micrograph of wear track region of aluminium oxide coat-
`ing number 12, showing transferred material from steel ball.
`
`Grinding marks on the substrate are perfectly repro-
`duced through a coating thickness of (in this case) 8 jim.
`Based on these results described above, the coatings
`were ranked in the following order of increasing wear
`resistance; run 8, run 13, run 7, run 9 and run 12, As
`mentioned earlier,
`these are preliminary results. The
`tribological properties of these coatings will be investi-
`gated in moredetail in the future.
`
`4. Discussion
`
`This investigation has demonstrated that fully dense,
`stoichiometric alumina coatings can be deposited at
`relatively high rates by closed-field unbalanced magnet-
`ron sputtering, provided the magnetron discharge is
`pulsed. Extremely dense coatings with high microhard-
`ness values were deposited at
`rates of up to 0.13
`um min~‘. This rate is equivalent to 47.5 and 39.4%,
`respectively, of the rates obtained for the deposition of
`
`References
`
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`weier, Germany.
`
`Ex. 1048, Page 5
`
`