APPARATUS AND PROCESS WITH A DC-PULSED CATHODE ARRAY

Abstract

An apparatus for sputter deposition of material on a substrate. The apparatus includes a deposition chamber and a cathode array mounted in the deposition chamber. The array has three or more rotating cathodes. Each cathode has a cylindric target of equal target length L.sub.T and a magnetic system. The cathodes are spaced from one another such that their longitudinal axes Y.sub.Cj are arranged parallel to each other, in a distance T.sub.SD from a substrate plane S, and spaced apart along a projection of a substrate axis X in a distance T.sub.TT, whereat each cathode of the cathode array includes a magnetic system. The magnetic system of at least one cathode is swivel mounted round respective cathode axis Y.sub.Cj to swivel the magnetic system into and out of a swivel plane P.sub.TS. A pedestal is designed to support at least one substrate of maximal dimensions x*y to be coated in a static way. The pedestal is positioned in the deposition chamber in front of and centered with reference to the cathode array. At least one pulsed power supply is configured for supplying and controlling a power to at least one of the cathodes.

Claims

1. An apparatus for sputter deposition of material on a substrate, said apparatus (30) comprising: a deposition chamber (31); a cathode array mounted in the deposition chamber, said array having three or more rotating cathodes (1,2,3,4,n), each cathode having a cylindric target (5,6,7,8,n) of equal target length L.sub.T and a magnetic system (9,10,11,12,n), the cathodes being spaced from one another such that their longitudinal axes Y.sub.Cj are arranged parallel to each other, in a distance Tse from a substrate plane S, and spaced apart along a projection of a substrate axis X in a distance TTT, whereat each cathode of the cathode array comprises a magnetic system (9,10,11,12,n) and the magnetic system (9,12,n) of at least one cathode is swivel mounted round respective cathode axis Y.sub.Cj to swivel the magnetic system into and out of a swivel plane P.sub.TS; a pedestal (15) designed to support at least one substrate (14) of maximal dimensions x*y to be coated in a static way, the pedestal being positioned in the deposition chamber in front of and centered with reference to the cathode array; at least one pulsed power supply (13) configured for supplying and controlling a power to at least one of the cathodes.

2. The apparatus of claim 1, whereat the following applies:
(T.sub.LA−3.9 MT.sub.SD)≥y.sub.max≥(T.sub.LA−2 MT.sub.SD) whereat T.sub.LA is the length of an active region on the target surface, y.sub.max is a maximum substrate dimension parallel to longitudinal axes Y.sub.Cj, MT.sub.SD is the mean shortest distance between the outer target diameter D.sub.Tn and the substrate plane S.

3. The apparatus of claim 2, whereat MT.sub.SD≈T.sub.SD1≈ . . . ≈T.sub.SDn.

4. The apparatus according to claim 1, whereat a distance T.sub.TT between the axes of neighboring cathodes is equal for all distances T.sub.TTK-n between neighboring cathodes.

5. The apparatus according to claim 1, whereat the cathodes are spaced equidistantly in a normal distance T.sub.SC from the substrate plane S.

6. The apparatus according to claim 1, whereat the distance T.sub.SCo of at least one or both outer cathodes to the target plane S is different to the distance T.sub.SCi of the inner cathodes to the target plane S.

7. The apparatus according to claim 1, whereat for an angle α between swivel plane PTs and the substrate plane S the following applies: 40°≤α≤100°.

8. The apparatus according to claim 1, whereat for a maximum swivel angle β of the at least one swivel mounted magnetic system the following applies: ±0°≤|β⊕≤±80°.

9. The apparatus according to claim 1, whereat the pulsed power supply is a bipolar pulsed power supply.

10. The apparatus according to claim 9, whereat the bipolar power supply is configured as a dual magnetron supply, the outputs of different polarity being electrically connected with the inputs of two neighboring electrodes.

11. The apparatus according to claim 1, comprising at least two pulse power supplies connected to a pulse synchronizing unit.

12. The apparatus according to claim 1, whereat both outer cathodes are connected to DC power supplies.

13. The apparatus according to claim 1, whereat the pedestal is electrically isolated.

14. The apparatus according to claim 13, whereat the pedestal is connected to an RF supply.

15. The apparatus according to claim 1, whereat the pedestal is electrically grounded.

16. The apparatus according to claim 1, comprising a gas distribution system for providing one or more process gases;

17. The apparatus according to claim 1, whereat the anode is a ground anode formed by the process chamber.

18. Process to deposit a coating comprising: the use of providing the apparatus according to claim 1, whereat a substrate is mounted to and positioned with the pedestal in the deposition chamber, a vacuum is applied to the deposition chamber and a process gas is introduced to the chamber, depositing the coating on at least one flat substrate within the dimensions x*y in the target plane S by applying a pulsed target power to at least one cathode of the array.

19. Process according to claim 18, whereat:
(T.sub.LA−3.9 MT.sub.SD)≥y.sub.max≥(T.sub.LA−2 MT.sub.SD) whereat T.sub.LA is the length of an active region on the target surface, y.sub.max is a maximum substrate dimension parallel to longitudinal axes Y.sub.Cj, MT.sub.SD is the mean shortest distance between the outer target diameter D.sub.Tn and the substrate plane S.

20. Process according to claim 18, whereat a coating thickness uniformity unif.sub.T<5% is produced within the substrate dimensions x*y.

21. Process according to claim 18, whereat at least one power supply is a bipolar power supply.

22. Process according to claim 21, whereat two neighboring cathodes are driven by a bipolar pulsed power supply in a dual magnetron configuration with an output of different polarity connected to each neighboring electrode.

23. Process according to claim 18, whereat a Chrome (Cr), copper (Cu), tantalum (Ta), titanium (Ti), tungsten (W), or tungsten titanium (WTi) coating is deposited by sputtering of Cr, Cu, Ta, Ti, W, or WTi targets.

24. Process according to claim 18, whereat the substrate is mounted electrically floating or on an RF potential.

25. Process according to claim 18, whereat the substrate is mounted electrically grounded.

26. The process according to claim 18, wherein the coating has a uniformity unif.sub.R of the specific resistance R [Ωm] of unif.sub.R<5% within the substrate dimensions x*y.

27. The process according to claim 18, wherein the substrate is manufactured to include the coating having a thickness uniformity unif.sub.T≤5% within the substrate dimensions x*y.

Description

FIGURES

[0041] The invention shall now be further exemplified with the help of figures. Figures are drawn exemplarily for mere demonstrative purposes only and therefore do not show actual equipment dimensions, nor do they show details known to the man of art but not essential for the understanding of the present invention. Same numbers and reference signs refer to same features also with different figures. Apostrophes and subscripted indices “i” for features of an inner cathode, and “o”, for features of an outer cathode, or numbers refer to alternatives or specific features of a specific cathode. The figures show:

[0042] FIG. 1: apparatus vertical projection

[0043] FIG. 2: apparatus horizontal projection

[0044] FIG. 3: deposition in substrate plane S

[0045] FIG. 4: cathode side view

[0046] FIG. 5: thickness distribution along X-coordinate

[0047] FIG. 6: pulse scheme (bi-polar)

[0048] FIG. 7: pulse scheme (dual magnetron)

[0049] FIG. 8: simulated thickness scheme

[0050] FIG. 9: thickness distributions along y-coordinate (DC)

[0051] FIG. 10: relative thickness along y-coordinate (DC)

[0052] FIG. 11: relative thickness along y-coordinate (pulsed)

[0053] FIG. 12: surface scan thickness distribution (DC)

[0054] FIG. 13: surface scan thickness distribution (pulsed)

[0055] FIG. 1 is a vertical projection along central axes X and Z of an inventive apparatus 30 comprising a four cathodes 1,2,3,4 array. The cathodes being equipped with rotating targets 5,6,7,8 and swivel mounted magnetic systems 9,10,11,12, both moving round respective longitudinal axes Y.sub.C1,Y.sub.C2,Y.sub.C3,Y.sub.C4 of the cathodes. Magnetic systems 10 and 11 are shown in a facing position to the substrate surface or substrate plane S, whereas magnetic systems 9 and 12 are swiveled towards the center, with all magnetic systems shown as positioned within their respective swivel plane P.sub.TS defining the center of a respective total swivel angle 2β, e.g. for the swivel angles of the inner cathodes, here with an angle α.sub.i=90° between a swivel plane P.sub.TSi of an inner cathode 2,3 and the substrate plane S, 2β.sub.i=|+β.sub.i|+|−β.sub.i| and |−β.sub.i|=|+β.sub.i|, the same is valid for ±β.sub.o, here with an angle α.sub.o=45° between the swivel plane P.sub.TSo of an outer cathode 1,4 and the substrate plane S. With such a configuration outer and inner swivel angles will be usually different, e.g. β.sub.o<β.sub.i, to avoid positions where magnetic systems might face the next neighboring cathode and mutual cathode deposition would take place.

[0056] With inner cathode 2 and outer cathode 4 the shaft 33 of the cathode axes Y.sub.C2,Y.sub.C4 and transmission spokes 34 are shown, whereas with outer cathode 1 and inner cathode 3 inner and outer swivel planes P.sub.TSi, P.sub.TSo (dash-pointed lines) and respective inner and outer swivel angles ±β.sub.i, ±β.sub.o (dashed lines) are shown exemplarily. The cathode arrangements 1,2 with magnetic systems 9,10 can be seen as mirrored in the YZ-plane to respective arrangement 3,4 with magnetic systems 11,12. The angle α.sub.i of the inner swivel planes P.sub.TSi is normal to the substrate plane S, whereas the angle α.sub.o of the outer swivel planes P.sub.TSo are inclined at nearly 45° to the substrate plane S, so that planes P.sub.TSo are oblique downward and to the central plane YZ seen from axes Y.sub.Co. Where indices “i” and “o” refer to inner and outer cathodes and respective dimensions, angles, swivel planes and the like. The maximum of the magnet swing out of the swivel planes P.sub.TS is given by respective angles ±β. Outer swivel angles ±β are about 20°, inner swivel angles ±β.sub.i are about 40°, which each can be varied up to the respective process needs. It should be mentioned that for many processes in the semiconductor industry, due to the thin layers, e.g. from some nanometers to about 500 nm, and high process efficiency which means a high cathode power applied, usually one magnet swing between the maximum positions, i.e. from +β position to −β position will suffice to deposit the required layer thickness. The swivel movement can be realized in a constant or a stepwise manner. Speed may vary or hold time may be different with consecutive swivel positions so that dwell time of the magnet system may vary and be different for instance for angle range +β to zero and range zero to −β. As shown with FIG. 1 and FIG. 2 cathode axes Y.sub.C2, Y.sub.C4 of the outer cathodes 1,4 may have an offset of some millimeters, e.g. 5 mm to 60 mm, to the maximum substrate dimensions in an x-direction. Alternatively, as shown with FIG. 3 they may be essentially flush, e.g. within ±10 mm, with the respective y-sides of the maximum substrate dimensions. In each case, axes of the outer cathodes will be symmetrical and in parallel to the center Y-axis.

[0057] Cathodes 1,2,3,4 with mounted targets 5,6,7,8 are of the same size, respective of the same diameter D.sub.T, arranged in equal distance T.sub.TT (i.e. T.sub.TTi=T.sub.TTo) from each other and in equal distance T.sub.SD (i.e. T.sub.SD1= . . . =T.sub.SD4) or at least in approximately equal distance MT.sub.SD−±2 mm from the target plane S. Alternatively, as shown in dotted lines, the position of the outer cathodes 1′, 4′ with targets 5′,8′ can be moved vertically, e.g. lowered as shown, so that the distance T.sub.SDo′ of the outer targets 1′, 4′ to the target plane is different to the distant T.sub.SDi of the inner targets 2,3 to the target plane S. In addition, position of the outer cathodes 1′, 4′ with targets 5′,8′ can be moved sidewise, e.g. towards the middle as shown, so that the distance T.sub.TTi between two inner targets is different to the distant T.sub.TTo between an outer target to the next inner target. Alternatives as discussed may help to improve layer uniformity parameters like (thickness or specific resistance) in an x-direction, e.g. when length x of the centrally positioned substrate would be shorter than the distance between the two outer axes in an arrangement of equal distances as shown with cathodes 1,2,3,4, or more formally expressed:

[00001]$x<\left\{\underset{k=1}{\overset{n}{.Math.}}{T}_{\mathrm{TTk}}\right\},\mathrm{here}x<3T_{\mathrm{TT}}=T_{\mathrm{TTi}}+2T_{\mathrm{TTo}}$

for: T.sub.TT=T.sub.TTk=1 . . . =T.sub.TTn (here n=3)
and at the same time: T.sub.SD≈T.sub.SDk=1≈ . . . ≈T.sub.SDm (here m =4) and T.sub.SC=T.sub.SCo=T.sub.Sci.

[0058] Therefore, an arrangement as shown with dotted cathodes 1′,2′,3′,4′ would allow to adjust the nearest distance of the outer cathodes to the substrate surface to be coated, e.g. to a distance value |T.sub.SDi| according to the normal distance T.sub.SDi of the inner cathodes 2 and 3. In such case of different target to substrate plane distances, the longer distance has to be used to calculate the minimum value of the target protrusions or to calculate the maximum y-value for the substrate area for a given cathode array. Such an arrangement may be helpful also when the outer cathodes are driven with a different power, e.g. with higher or lower power, or a different power supply like an AC or a DC-supply, see below.

[0059] As a counter-pole to the cathodes a ground anode 19 is provided encompassing the cathode array. This can be realized by respective liners or shields, e.g. encompassing and/or forming essentially the whole inner surface of the deposition chamber 31 with the exception of the cathodes 1,2,3,4 and the pedestal 15 for the substrate 14.

[0060] The pedestal encompasses further an isolation or an isolated ESC 16 to allow a biased, e.g. RF, grounded or floating substrate potential, up to the respective process needs. A cooling/heating circuit comprising a cooling or heating fluid inlet 17, and a fluid outlet 18 may be provided. Usually water will be used as cooling liquid.

[0061] The pedestal may be further provided with a back-gas supply 20 to enhance thermal transfer from the pedestal 15 to a flat substrate 14 mounted to it or vice-versa. A back-gas supply 20 may comprise a gas supply for at least one inert gas, e.g. He and/or Ar and at least one gas inlet 21a leading to the surface of the pedestal 15, e.g. in the surface of the isolated ESC 16. Alternatively, there may be several inlets or gas distribution ducts, e.g. leading from a center towards further outside pedestal or ESC surface areas and having a flow area to transport back-gas with a low flow resistance. The ducts may be in part or even completely open to the backside of the wafer and being connected to shallow but wide gas channels, e.g. from 10 μm to 100 μm, or 50±10 μm depth, having a considerable higher flow resistance than the ducts and covering an essential area of the pedestal/ESC surface to provide an effective thermal transfer between the wafer and the pedestal/ESC surface via the back-gas. Alternatively, the wafer may be positioned on spacers in a close distance above the pedestals or the ESCs surface, e.g. according to the channel depth as mentioned, thereby forming another kind of channel between the wafer and the pedestal/ESC. With both variations the substrate may be further positioned on a surrounding projection, e.g. a gasket to allow a higher back-gas pressure. In a further embodiment the projection may be provided with small outlet openings to the process atmosphere or a back-gas outlet 21b may be provided to lead the back gas directly to the pump socket 22 of the high vacuum pump 23.

[0062] Elevation rods 24 allow to move the pedestal in a vertical direction, e.g. to load the substrate 14 to the pedestal in a lowered position (not shown), to close the deposition chamber 31 and/or adjust the substrate to cathode distance in an upper position as shown.

[0063] A process gas inlet 36 for inert sputter gases like Argon, Neon and/or Krypton and, if reactive processes should be performed to deposit compounds of the target material, respective reactive gases comprising e.g. nitrogen, carbon, or oxygen, can be connected to a gas distribution system 37 to distribute process gasses evenly in the deposition chamber 31.

[0064] In FIG. 2 a system similar to FIG. 1 is shown in a horizontal projection. For same reference numbers it may be referred to FIG. 1. Cathodes 1,2,3,4 have target caps 35 to protect mechanical arrangements like drive gears 26 to move the targets 5,6,7,8 and other feedthroughs and will usually be provided with further target caps 35′, schematically shown with cathode 2 only, both to avoid particle exchange from the hollow target cathodes to the deposition chamber and vice-versa. Additionally caps 35, 35′ may be provided with vacuum gaskets and/or sealings for the target cooling system. As usual, only the target and respective voltage connection of the cathode will be connected to the respective voltage supply 13, whereas other parts of the cathode are isolated from the target and connected to ground.

[0065] Attention should be given to the different power supply systems the apparatuses of FIG. 1 and FIG. 2 are provided with. In FIG. 1, cathodes 1 or 1′ and 2, as cathodes 3 and 4 or 4′ are connected with respective two supplies 13 each in a dual magnetron configuration, with each pulse supply 13 providing its symmetric negative and positive signals alternatingly to cathodes 1 (1′) and 2 respectively to cathodes 3 and 4 (4′). A synchronizing unit 38 synchronizes the signals of the respective supplies 13. A typical voltage signal from a dual magnetron supply providing a signal symmetric in signal height and time is shown in FIG. 7.

[0066] Contrary to that with FIG. 2 each outer cathode 1, 4 and each inner cathode 2, 3 is provided with power supplies 13.sub.o and 13.sub.i respectively. In a first embodiment comprising dashed and solid connection lines between the synchronization unit 38 and power supplies, all power supplies 13.sub.o and 13.sub.i are pulse power supplies, however, need not fulfill the same signal criteria as dual power pulse supplies. As can be seen with FIG. 6 with such power supplies period time t may have a longer negative time span t− and a shorter positive time span t+ for the respective sub-periods, and height of the positive discharge voltage V+ can be essentially lower than the negative voltage V−. Even a positive spike discharge Sp as exemplarily shown on the right side of the graph may suffice to provide the effect of the invention to minimize the sidewise area of swing induced thickness asymmetries in cathode arrays.

[0067] In a further embodiment shown in FIG. 2 including only the solid connection lines between the pulse power supplies 13.sub.i of the inner cathodes 2,3 and synchronization unit 38, outer cathodes 1,4 may be provided with DC-supplies. It has to be understood that the power supply schemes as shown with FIG. 2 can be applied also to the cathode array as shown in FIG. 1, e.g. pulsed power supplies 13.sub.o or DC-supplies may be applied to the lowered and/or sidewise in an x-direction shifted outer cathodes 1′,4′ and at least one “inner” pulse power supply 13.sub.i can be connected to the inner cathodes either with a separate supply for every cathode or in a dual magnetron configuration comprising inner cathodes 2 and 3.

[0068] In FIG. 2 also the maximal substrate surface dimensions xy and their relation to the target dimensions, e.g. TL, the geometric target length, and T.sub.LA, the active target length referring to the target length at which sputtering takes place, are shown. With an ideal cathode design, which is strongly influenced by the type of the magnetic system 9, 10, 11, 12, T.sub.LA will equal to TL so that the whole target surface can be sputtered equally. It should be mentioned that only magnetic systems 9 and 11 are shown in FIG. 2 for reasons of clarity. FIG. 3 depicts the substrate plane S only out of FIG. 2 and shows further details like the respective protrusion T.sub.SD on both sides of the maximum dimension y of the substrate surface. Further on areas of higher thickness 45 diagonally opposed on both sides of each axis Y.sub.C1, Y.sub.C2, Y.sub.C3, Y.sub.C4 are shown in a centered plane of dimensions x=x and y=T.sub.LA. Areas 45 are provoked by as mentioned swing induced thickness asymmetries during swiveling of the magnetic systems round respective axes.

[0069] FIG. 4 shows further details of a cathode 1 in a side view with magnetic system 10 in solid lines facing the substrate 14 and in dashed lines swiveled and therewith inclined to the substrate plane S. The magnetic system 10 is swiveled within the inner space of the cooling tube 40 which can be at ambient atmosphere, the latter defining also the inner boarder of the cooling circuit 44 of the sputter target, the outer boarder being defined by a backing tube 39 which also gives mechanically support to the target. Respective vacuum gaskets and/or sealings for the target cooling system may be provided with caps 35, 35′. Target cooling water in- and outlets may be provided axially and be radially distributed, e.g. at opposite cathode ends.

[0070] In table 1 the key dimensions of two inventive apparatuses for two different substrate geometries are shown. Both apparatuses are of a modified Clusterline PNL type. For apparatus 1 (Appar.1), which is based on a Clusterline PNL500 model, substrates in the range of 500±15 m×500±15 mm could be coated with a three cathodes array. For apparatus 2 (Appar.2), which is based on a Clusterline PLN600 model, substrates in the range of 600±20 m×600±20 mm could be coated with a four cathodes array.

TABLE-US-00001 TABLE 1 Apparatus Geometry Unit Appar. 1 Appar. 2 Number of cathodes 1 3 4 y.sub.max mm 500 600 0.5(T.sub.LA − y.sub.max)/MT.sub.SD 1 1.42 1.91

[0071] The formula defines respective target protrusions as used per side of the respective substrates. Targets having a diameter D.sub.T from 140 mm to 160 mm have been used. Using such apparatuses, DC-power supplies for state of the art processes and bipolar pulsed DC-power supplies for inventive processes have been used with targets comprising swivel mounted magnetic systems. Parameters as shown in table 2 have been applied to show that swing induced thickness asymmetry could be effectively improved to enlarge the substrate surface in both y directions.

TABLE-US-00002 TABLE 2 Process parameters Unit Range 1 Range 2 Proc. pressure tot. mbar 1E−2-1E−4  5E−3-5E−4  Pulsed DC power W/targ.  100-10000 500-6000 Frequency kHz 50-350 50-150 Negative Pulse μs 2-15 5-15 width t− Target material — Al, trans. Me* Al, Cu, Gr. 4-10** MT.sub.SD mm 60-110  70-100 Chuck temperature ° C. 20-450 50-150 *Any transition metal, i.e. group 3 to 12 of the periodic system, or Al, or a combination thereof; **Any group 4 to 10 element, Al, or Cu, or a combination thereof.

[0072] Applying such parameters, coating properties could be reached as shown in table 3.

TABLE-US-00003 TABLE 3 Coating properties: Unit Example 1 Example 2 Material Nm Ti Cu Thickness nm 50-250 100-500 Thick. Uniformity, unif.sub.T % ≤5 ≤5 Specific resistance R μOhms*cm ≤85 ≤2.6 R uniformity, unif.sub.R % ≤5 ≤5

[0073] With parameters as listed above a thickness distribution as shown in FIG. 5 could be deposited along the central x-coordinate of the substrate normal to cathode axes Y.sub.Cn of a 4 cathodes array using Cu-targets. It should be mentioned that in case of a distribution along the X-axis relative thickness variations of coatings deposited by a DC- or a pulsed DC-driven process are about the same, as swing induced thickness asymmetries can be seen in outer y-coordinates of the substrate plane S only. Such deviations along the X-axis have been optimized up-front by an optimization program as commercially available from Sputtering Components Incorporation. An example of such calculations for a four cathodes array is shown in FIG. 8. The cumulative curve of the superposition of the thickness distributions of the four cathodes as shown gives a central uniformity deviation of about ±0.34%. Such optimization when applied to a PNL600 sputtering system resulted in a central uniformity deviation of about ±2% in case of the Cu-layer from FIG. 5. As shown with the four cathode array of FIG. 1 and FIG. 2 the projections of the axes Y.sub.C1 and Y.sub.C4 of the outer cathodes are offset outward from the maximum substrate dimensions.

[0074] In FIGS. 10 and 11 comparative thickness distributions of two titanium single layers deposited in a Clusterline PNL600 system are shown. For apparatus geometries of PNL600 equipment as used, see table 1, column Appar.2. The thickness distribution was measured along a line with constant x-coordinate in parallel to cathode axes Y.sub.Cj and a center axis Y of a 600 m×600 mm substrate surface plane. For these experiments only cathode two of the four cathode array has been used in DC-mode according to a state of the art process, and with a stationary magnetic system in a non-pivoted zero position, in opposition to the substrate plane S, and in a pivoted position with a pivot angle Υ=60° from the zero position of the magnetic system. It should be noted that Υ=0° and Υ=60° refer to respective swivel plane angles α=90° and α=30° towards the substrate plane S and swivel angles β=0°, as with this experiments the magnetic system was used stationary. The distance x has been chosen according to the highest absolute thickness along the X-axis of the substrate surface, which also refers to the highest relative thickness with any other y-value of the same x-coordinate due to the orthogonal arrangement of the cathode axis Y.sub.Cj to the X-axis. That maximum thickness value is, in case of a stationary magnetic system at about x=400 mm, the place where the target faces the substrate at normal distance TsD2, the magnetic system being directed towards the substrate.

[0075] In case of a pivoted magnetic system at Υ=60° from the zero position towards the central ZY-plane, the thickness maximum can be found shifted sidewise towards the center at about 325 mm, the substrates center being at 300 mm. Measuring points for deposition with a magnetic system in zero position are square and denominated DC Υ=0°, measuring points for deposition with a pivoted magnetic system are circular and denominated Υ=60°. A middle thickness of about 375 nm can be calculated from FIG. 9 when the cathode was driven in a stationary mode and a respective thinner middle thickness of about 280 nm could be calculated for the pivoted cathode. However more interesting than the absolute thicknesses as shown in FIG. 9 are relative thicknesses, normalized to the respective middle thicknesses of the two coatings as shown in FIG. 10.

[0076] From there a thickness uniformity unif.sub.T(Υ=0°)=±1.5% can be deduced for a deposition in the zero position of magnetic system, whereas the thickness uniformity achieved with the pivoted magnetic system was very poor with uniformity unif.sub.T(Υ=60°)=±7.8. At the same time the distribution is highly asymmetric being thin at one end and thick at the other end of the y-coordinates. It should be noted again that these measurements were made on one x-coordinate of maximum thickness only. Taking into account a thickness distribution of the whole substrate surface it is clear that despite optimization programs for the thickness distribution along a central x-coordinate, as shown with FIG. 8, thickness non-uniformities along y-coordinates are still a challenge. These results also clearly show the need to provide excessive protrusions over the substrate dimensions with both target ends, e.g. ≥2 T.sub.SD at each side, to arrive at an at least somehow acceptable thickness uniformity along the y-coordinates when pivoted or swiveled magnetic systems are used to optimize the thickness distribution along the x-coordinates of a substrate coated statically with an anode array arrangement. It should be mentioned that this effect isn't of a similar importance for inline systems where substrates are moved through zones of different deposition rates whereby thickness differences in x-direction are leveled, and thus the magnets can always stay at α=90° and do not need to be pivoted or swiveled.

[0077] In FIG. 11 the results of similar comparative relative thickness distributions of titanium coatings deposited with a stationary magnetic system as with FIG. 10 are shown. In this case however contrary to state of the art processes in FIG. 9 and 10 a bipolar pulsed DC-power supply has been connected to the only powered cathode three of the array. Measuring points for deposition in zero position, here of cathode 3, denominated as pulsed DC Υ=0° are square, measuring points for deposition with a pivoted magnetic system are triangular and denominated pulsed DC Υ=60°. The difference to the DC driven cathode is very surprisingly to the man of art, as the uniformity of the thickness distribution with a magnetic system pivoted by Υ=60° an about 3-fold smaller deviation from the uniformity, namely unif.sub.T(Υ=60°)=±2.1, could be attained compared to the respective DC-driven pivoted cathode as shown in FIG. 10. At the same time the symmetry of the distribution is now similar to the distribution of the coatings deposited with a non-pivoted system showing a slightly thicker central region and a respective decease of the coating thickness towards the side areas.

[0078] FIG. 12 and FIG. 13 show a surface scan thickness distribution of a coating deposited with a state of the art DC-process respectively with an inventive pulsed-DC process on a PLN600 (appar.2) system as schematically shown in FIG. 1 and FIG. 2 and respective dimensions in table 1. All four cathodes, respectively copper targets were at the same distance T.sub.SD from the cathode plane S. Power was supplied by four dedicated DC-supplies for the state of the art process and by four pulsed and synchronized DC-supplies for the inventive process.

[0079] The results of surface area measurements of the thickness uniformity on a 600 m×600 mm glass substrate with an edge exclusion of 10 mm for DC sputtering showing distinct swing induced thickness asymmetry is shown in FIG. 12. For practical reasons, with FIG. 12 and 13 the axes origin is in the left lower corner of the substrate. The gray scale is adjusted to show a range of −15% to +15% relative to mean value. The state of the art process in FIG. 12 resulted in a mean thickness of about 238 nm and a uniformity unif.sub.T=7.6 within the substrate dimensions as measured. The measurements were performed with a 4-point probe surface resistance Rs measurement device and measured sheet resistance was transferred to film thickness values assuming constant specific resistivity.

[0080] The same measurement on a respective glass substrate coated with a pulsed-DC process according to the present invention however resulted in a mean thickness of about 205 nm and a uniformity unif.sub.T<5.0 between the minimum and the maximum value, which is more than 30% better than the uniformity of the DC-process. Especially in the side areas between with 200≥y and 400≤y topographic differences are remarkably lowered.

[0081] Experimental results as shown with FIG. 9 to FIG. 13 therefore clearly show that thickness-uniformity can be considerably improved by use of bipolar pulsed power supplies whereby substrate surface can be enlarged with a given cathode geometry, or cathode length can be reduced with a given substrate geometry.

REFERENCE NUMBERS

[0082] 1 cathode (electrode in case of dual magnetron supply) [0083] 2 cathode (electrode in case of dual magnetron supply) [0084] 3 cathode (electrode in case of dual magnetron supply) [0085] 4 cathode (electrode in case of dual magnetron supply) [0086] 5 target [0087] 6 target [0088] 7 target [0089] 8 target [0090] 9 magnetic system [0091] 10 magnetic system [0092] 11 magnetic system [0093] 12 magnetic system [0094] 13 pulse power supply [0095] 13′ power lines [0096] 14 substrate [0097] 15 pedestal [0098] 16 isolation, or isolated ESC (electrostatic chuck) [0099] 17 cooling liquid in [0100] 18 cooling liquid out [0101] 19 anode [0102] 20 back-gas supply [0103] 21a back-gas inlet [0104] 21b back-gas outlet [0105] 22 pump channel [0106] 23 pump [0107] 24 elevation rods [0108] 25 target drive [0109] 26 drive gear [0110] 27 bottom [0111] 28 sidewalls [0112] 29 top [0113] 30 apparatus [0114] 31 deposition chamber [0115] 32 magnet motor [0116] 33 shaft [0117] 34 spokes [0118] 35 target cap [0119] 36 process gas inlet [0120] 37 gas distribution system [0121] 38 synchronizing unit [0122] 39 backing tube [0123] 40 cooling tube [0124] 41 inner magnets [0125] 42 outer magnets [0126] 43 magnet yoke [0127] 44 cooling circuit [0128] 45 area of higher coating thickness [0129] i, o indices i and o refer to inner and outer cathodes and respective dimensions, angles, swivel planes, power supplies . . . [0130] α.sub.o, α.sub.i angle between plane P.sub.Tso, P.sub.TSi and the vertical [0131] β, β.sub.i, β.sub.o max. swivel angle of (inner/outer) magnet system [0132] C.sub.L cathode length [0133] D.sub.T target diameter; D.sub.T indicates any of the target diameters D.sub.T1 . . . D.sub.Tn, D.sub.Tmax, D.sub.Ti, or D.sub.To; [0134] P.sub.Tso, P.sub.TSi swivel plane for magnets of outer, inner cathode [0135] S substrate plane [0136] Sp electric spike [0137] T.sub.L target length [0138] T.sub.LA length of an active target surface region [0139] T.sub.SC distance cathode axis to substrate plane S; T.sub.SC indicates any of the distances T.sub.SCi or T.sub.SCo which can be equal or different [0140] T.sub.SD distance target to substrate plane S; T.sub.SD indicates any of the distances T.sub.SD1 . . . T.sub.SDn, T.sub.SDi, T.sub.SDo′, and MT.sub.SD which can be equal or different [0141] MT.sub.SD mean distance value MT.sub.SD=(T.sub.SD1+ . . . +T.sub.SDn)/n [0142] T.sub.TT distance between target axes; T.sub.TT indicates any of the distances T.sub.TTi or T.sub.TTo which can be equal or different [0143] x*y maximal dimensions of the substrate surface [0144] X,Y,Z axes [0145] Y.sub.cj longitudinal axis of the cathode; Y.sub.cj indicates any of the axes Y.sub.C1 . . Y.sub.C4, Y.sub.Ci and Y.sub.Co;