JP2009503255A - Method and apparatus for sputtering on large flat panels - Google Patents

Abstract

  A magnet of opposite polarity (164) arranged on the back of the rectangular sputter target (16) and arranged to form a gap therebetween corresponding to the plasma track proximate to the target to enhance the plasma A rectangular magnetron (160) for coating the rectangular panel (14) with the material sputtered from the target. The gap extends with a closed loop having a serpentine or helical shape. The magnetron is somewhat smaller in size than the target and is scanned in two perpendicular directions of the target. The scan length is, for example, about 100 mm for a 2 m target. The scan follows a double Z pattern along two links parallel to the target side and two connecting diagonals. Suspended from a gantry (364) that slides vertically at the chamber wall (276), an external actuator (416) moves the magnetron along a two-dimensional path.

Description

Field of Invention

  The present invention generally relates to sputtering of materials. In particular, the present invention relates to magnetron scanning that creates a magnetic field to improve sputtering from a rectangular target.

  Over the past decade, technology has been focused on producing, for example, flat panel displays (FPDs) used for computer displays, and more recently for television screens. Sputtering is a preferred approach in flat panel manufacturing where deposition is performed on large, generally rectangular panels. The panel is made of glass, polymer panel or flexible sheet, and includes a conductive layer including a metal such as aluminum or molybdenum and a transparent conductor such as a conductive metal oxide, for example, indium tin oxide (ITO). I have. The finished panel incorporates thin film transistors, plasma displays, field emitters, liquid crystal display (LCD) elements or organic light emitting diodes (OLEDs). A solar cell having a pn or pin junction may be similarly formed on a low cost substrate. Similar techniques may be used to coat glass windows with optical layers and to form color filters on FPDs. In particular, it may be used to manufacture solar cells on a lower cost substrate. Flat panel sputtering is fundamentally distinguished from the long-developed wafer sputtering technology due to the large size of the substrate and its rectangular shape. Demaray et al. Describe such a flat panel sputter reactor in US Pat. No. 5,565,071, incorporated herein by reference. The reactor includes a rectangular-shaped sputtering pedestal electrode 12, as illustrated in the schematic cross-sectional view of FIG. 1, which is typically electrically grounded and within the vacuum chamber 18, The rectangular glass panel 14 or other substrate is held on the opposite side of the rectangular sputtering target 16. The target 16, at least the surface made of the metal to be sputtered, is vacuum sealed to the vacuum chamber 18 with the isolator 20 therebetween. Typically, the sputtered metal layer is bonded to a backing plate, where cooling water channels are formed to cool the target 16. A sputtering gas, typically argon, is supplied to a vacuum chamber 18 held at a pressure in the millitorr range. Advantageously, the back chamber 22 is vacuum sealed to the back of the target 16 and evacuated to a low pressure to substantially eliminate the pressure differential between the target 16 and its backing plate. This makes it possible to create a much thinner target assembly. When a negative DC bias is applied to the conductive target 16 with respect to the pedestal electrode 12 or other grounded part of the chamber such as a wall shield, the argon is ionized into plasma. Positive argon ions are added to the target 16 from which metal atoms are sputtered. The metal atoms are directed partially to the panel 14 and deposit thereon a layer at least partially composed of the target metal. During metal sputtering, metal oxides or nitrides may be deposited in a process called reactive sputtering, with additional supply of oxygen or nitrogen to chamber 18.

  In order to increase the sputtering rate, a linear magnetron 24 shown in the schematic bottom view of FIG. There is a central magnetic pole 26 which is a vertical magnetic pole, and an outer magnetic pole 28 of opposite polarity surrounds it, causing a magnetic field to protrude parallel to the front surface of the target 16 in the chamber 18. The two magnetic poles 26, 28 are separated by a substantially constant gap 30 so that a high density plasma is formed in the chamber 18 under proper chamber conditions and flows into a closed loop or track. The outer magnetic pole 28 is composed of two straight portions 32 connected by two semicircular arc portions 34. As the magnetic field traps electrons, the density of the plasma increases and, as a result, the sputtering rate of the target 16 increases. Since the widths of the linear magnetron 24 and the gap 30 are relatively small, the magnetic flux density becomes high. The closed shape of the magnetic field distribution along a single closed track forms a plasma loop that generally follows the gap 30 and prevents plasma leakage from the ends. However, since the size of the magnetron 24 is small with respect to the target 16, it is necessary to scan the magnetron 24 in a straight line from the back surface of the target 16 in a direction crossing the long dimension of the linear magnetron 24. Typically, a lead screw mechanism drives linear scanning. This is disclosed for a more complex magnetron in Halsey et al., US Pat. No. 5,855,744. Although horseshoe magnets may be used, preferred structures include a number of cylindrical strong magnets, eg, NdBFe, arranged in opposite directions between the two shown polarities in the shown pole shape. A pole piece may cover the operating surface, define a pole surface, and magnetically couple a magnetic yoke that bridges the two poles 26, 28 to the other end of the magnet.

  De Bosscher et al. Described such linear magnetron coupled two-dimensional scanning in US Pat. Nos. 6,322,679 and 6,416,639.

The described magnetron was originally developed for a rectangular panel with a size of about 400 mm x 600 mm. Over the years, however, panel sizes have been increasing in size both for economies of scale and for providing larger display screens. Reactors have been developed for sputtering into panels having a size of about 2mx2m. In certain generation, and it processes the panel having a size of 1.87Mx2.2M, because the total area of more than 40,000 cm ^2, are referred to as 40K. The size of the next generation called 50K is over 2m on each side. However, the present invention is implemented for solar cells, especially when the substrate is not a glass panel but other more economical substrates, including roll substrates having components that are continuously provided to the sputtering apparatus. be able to. The width of the linear magnetron is usually limited relatively narrow when a high magnetic field is to be generated. As a result, for large panels with minimum dimensions of over 1.8 m, linear magnetrons are becoming increasingly ineffective and long deposition times are required to uniformly sputter large targets and coat large substrates. is there.

  One method for dealing with large targets is to repeat the racetrack magnetron 24 of FIG. 2 laterally along the scan direction, up to nine times to cover the majority of the target. See US Pat. No. 5,458,759, Hosokawa et al. Scanning is still desirable to average the magnetic field distribution. However, this iterative approach has several drawbacks. First, it is considered that the separated magnetron does not optimally use the magnetic field of the constituent magnets. That is, the effective magnetic field is lower than possible. Secondly, the generation of a large number of particles has been observed during plasma striking in the portion of the magnetron near the plasma dark shield near the arc portion 34 of the outer pole 28 of the racetrack magnetron 24. It is believed that electrons are leaking from the plasma to the adjacent shield. A striking voltage of about 800 VDC is required. Such a high voltage is considered disadvantageous because it produces excessive particles. Third, in the prior art using the single racetrack magnetron 24 of FIG. 2, the magnetrons are scanned with each other at relatively high speeds over a large portion of the target size, during a typical 1 minute sputter deposition period. Perform 30-40 scans. Such high scan speeds require difficult mechanical designs for fairly heavy magnetrons that cover the majority of large targets. Fourth, a scanning magnetron that includes one or more racetrack magnetrons does not completely solve the uniformity problem. The side end portion of the target 16 below the end of the racetrack magnetron 24 receives a high time integral magnetic flux. This is because most of the arc portion 34 extends along the scanning direction. Also, the axial end of the target underneath the magnetron receives a high time integral magnetic flux for the finite time required to reverse the direction even if the scanning direction is reversed. In this way, the target ends are eroded unevenly, reducing target usefulness and target life, and leading to non-uniform deposition.

Summary of the Invention

  One aspect of the present invention includes magnetrons having convoluted plasma loops, particularly those having a generally rectangular profile. The loops may be arranged in a serpentine shape with parallel straight portions connected by curved portions, or a rectangular spiral shape with straight portions arranged along an orthogonal direction. The plasma loop may be formed between an inner magnetic pole of one magnetic polarity formed in a convoluted shape and an outer magnetic pole of the opposite magnetic polarity surrounding it. The inner pole preferably has a simple curved shape that can be described as extending along a single path with two ends. Sputter erosion uniformity increases when one or two outer ends of the plasma loop extend to a tail that extends outside the useful rectangular profile.

  The loop may be twisted around the center with multiple wraps, eg, 2, 4 or 6 or more wraps. The rectangular spiral loop may be formed by a curved plasma loop that wraps around the center.

  The convoluted shape follows a path that preferably has a straight portion that is at least 50% of the total path length, preferably greater than 75%.

  The plasma loop follows a curved track surrounded by two magnetic poles, and it has been demonstrated that excellent results can be obtained if the parallel portions are separated by a pitch of 50-125 mm, 75 mm. The scan must be over a distance longer than this pitch, for example at least 10 mm longer.

  The magnetron is only somewhat smaller than the target being scanned, and the target may be relatively large, corresponding to a rectangular flat panel substrate with a minimum dimension of at least 1.8 m. The magnetron has an effective magnetic field that extends in a region having sides that are at least 80% and more than 90% of the corresponding dimensions of the target.

  Another aspect of the invention involves scanning the magnetron along the two dimensions of a rectangular target. It is possible to scan along a single diagonal of a rectangular target. However, it is preferred that the two dimensions of the scan are not fixed together. The scanning speed is relatively low, for example 0.5-5 mm / s, and the corresponding scanning time is 20-200 s. For a panel, a single scan time is sufficient.

  A preferred scan pattern is double Z with continuous scan, which is along the two opposite sides of the rectangle aligned with the sides of the target and connects the ends of the sides of the rectangle 2. Made along two diagonals. If the magnetron is sufficiently far from the frame at the end of the target, the target output may be turned off, scanning along the side may be reduced, or left on. The double Z scan may be repeated with a slight displacement between the scans, preferably in the direction perpendicular to the two sides, and then between the adjacent scans in the other vertical direction. More preferably. The displacement offset is in the range of 5-15 mm, preferably 8-12 mm.

  Diagonal and other scans that are tilted with respect to the Cartesian coordinates of the target are preferably made in a zigzag pattern along the Cartesian coordinates. The length of each linear portion of the zigzag pattern is preferably 0.4 to 3 mm, more preferably 0.8 to 1.2 mm.

  Yet another aspect of the present invention is to move the scanned magnetron, preferably a distance of 1-5 mm, from the ground frame or shield defining the chamber walls prior to plasma ignition.

  By using a strong magnet near the center, or by placing one or more magnetic shims between the magnet near the center and the yoke, the center magnet is closer to the target and the plasma loop is a magnet of different strength Or by extending to shimmed and unshimted portions of the magnetron plate, the magnetic uniformity is improved.

  The magnet may be held magnetically by a magnetic magnetron plate acting as a yoke and arranged side by side with an opposite non-magnetic retainer screwed to the magnetron plate. The retainer may be split into curved retainers connected in a vertical set. The retainer has a serrated inner end and may have one or two alternating rows of columnar magnets in between.

  The magnetron may be at least partially supported and scanned by an overhead mechanism. The overhead mechanism is a pair of vertically arranged rails that slide by two separate actuators in two vertical directions. Two actuators are sufficient, but with an additional actuator, only a pushing action is possible. Alternatively, the magnetron may be pushed along the surface of the target assembly at least partially supported by the target assembly through a slider or roller.

Detailed Description of the Preferred Embodiment

  One aspect of the present invention includes a convoluted magnetron shape rather than the linear racetrack of FIG. By convoluted is meant a magnetron that forms a closed plasma track, that is, it includes a curved portion that extends into an arc of greater than 360 °, preferably greater than 720 °. In another definition, the linear racetrack magnetron is twisted to maintain a substantially constant separation of the gap portions leading to parallel plasma tracks, for example, in a fold or spiral shape. In one embodiment, schematically illustrated in the plan view of FIG. 3, the serpentine magnetron 40 formed in the magnetron plate 42 includes a number of long parallel straight portions 43 arranged at a pitch P that are connected flat by the ends 44. Contains. The end 44 may be arcuate or may be a short straight part with a curved corner connecting the straight part 43. The serpentine magnetron 40 is curved in parallel sections from one side to the other and has a substantially short section adjacent to two sides perpendicular to the side. Since the magnetron described herein is generally molded to form a closed plasma loop, the illustrated pitch P is referred to as the loop pitch and is distinct from the track pitch described below. The effective area of the serpentine magnetron 40 defined by the substantially rectangular outline outside the magnetic field distribution parallel to the target surface is the majority of the target area. The serpentine magnetron 40 is scanned across the long straight section 43 beyond a distance closely related to the order of the pitch P. This is because the target region is completely scanned to more uniformly sputter the material from that region of the target.

  In the related embodiment outlined in the plan view of FIG. 4, the helical magnetron 50 includes a series of straight sections 52, 54 that extend along a vertical axis and are rectangular. They are smoothly connected together in a spiral. Adjacent parallel straight portions 52 or 54 are separated by a loop pitch Q. The helical magnetron 50 is considered a number of wraps around the center point of the magnetron. The helical magnetron 50 is scanned in one of the rectangular directions beyond the track pitch Q, which is half the loop pitch P, for example along the straight portion 54.

  The magnetron shape described above is somewhat schematic. The number of folds or wraps in the magnetrons 40, 50 may be greatly increased. Although not required, each magnetron is considered a fold or spiral wrap version of the elongate racetrack magnetron of FIG. A plasma loop is formed between the inner magnetic pole and the surrounding outer magnetic pole. When the linear magnetron 24 of FIG. 2 is bent, the magnetic poles of the adjacent bent portions are fused. As shown in the plan view of FIG. 5, the serpentine magnetron 60 is formed by an inner magnetic pole 64, an outer magnetic pole 66 that completely surrounds the inner magnetic pole 64, and a closed meandering gap 62 therebetween. The plasma loop includes two closely spaced non-parallel spreading plasma tracks, which are separated by a track pitch Q, are curved, and are approximately periodic in the x-direction shown in the cycle of the track pitch Q. There is formed a structure having a substantially constant end along the y direction. The single curved track, that is, the magnetron, has a shape substantially following a long straight portion 68 extending symmetrically in one direction around the center line M and a short straight portion 70 extending in the other direction. The curved portions 72, 74, 76 connect the straight portions 68, 70. Inner curve portion 74 and end curve portion 76 are sharply curved at approximately 180 °. In the figure, the outermost portion of the outer pole 66 is shown thinner than the inner portion, which represents the relative magnetic flux density. It is believed that the serpentine magnetron 60 may include additional folds of the plasma loop, especially for large target sizes.

  However, when testing such a serpentine magnetron 60, the target region 78 under the end curved portion 76 of the magnetron 60 exhibited a very low sputtering rate. Rather than increasing the scan length or increasing the overall size of the magnetron, the improved serpentine magnetron 80 shown in the plan view of FIG. 6 includes a tail portion 82 and both inner and outer poles 64, 66 are included. Both extend to a region surrounding the end curved portion 84 of the gap 62, and the end curved portion 84 is outside the rectangular outer shape of the effective region of the magnetron 80. As a result, the region 78 that is not so eroded in FIG. 5 is outside the effective target region. The target needs to be somewhat larger to accommodate the tail portion 82, but there is less sputtering, so the tail portion 82 extends closer to the target periphery than the rest of the magnetron 80 and possibly , May extend to the end of the target. When the number of times the plasma loop is bent is odd, it is considered that two tail portions 82 are formed on the opposite side surfaces of the magnetron plate 42. A similar tail portion 82 may extend from a single outer end of the helical magnetron 50 of FIG.

A double comb magnetron 90 shown in the plan view of FIG. 7 includes an inner magnetic pole 92 formed by two opposing rows of substantially straight tooth portions 94 and an outer magnetic pole 96 separated from the inner magnetic pole by a closing gap 98. Contains. Linear portion of the gap 98 is arranged in two lines Q _1, Q ₂ around a substantially symmetrical. The serpentine magnetrons 60, 80 and the double comb magnetron 90 are similar in phase but different in appearance and provide similar magnetic field distributions. Both advantageously have a linear portion of at least 50%, preferably more than 75% of the total track length. However, the comb magnetron is distinguished from the meandering magnetron 60 and the helical magnetron described below by its inner magnetic pole 92 having a complicated shape with many protrusions, and a single twisting the elongated linear magnetron 24 of FIG. The path cannot explain it. In contrast, the inner poles of serpentine and helical magnetrons have a substantially constant width and follow a single convolution or folding path that extends from one end to the other. In other words, the inner poles of serpentine and helical magnetrons have only two ends defining the ends of the closed plasma loop, while the inner poles of the comb magnetron are It has three or more ends, many of which are equivalent ends. As will be described later, these ends advantageously cause problems that are clearly related to their tight curvature, so it is advantageous to minimize their number. Hope et al. Disclose a single comb magnetron in US Pat. No. 4,437,966, and Ribeiro describes a double comb magnetron in US Pat. No. 4,826,584. is doing.

  The rectangular spiral magnetron 100 shown in the plan view of FIG. 8 has continuous grooves 102 and 104 formed in a nonmagnetic magnetron plate 106 made of, for example, 6061 aluminum. Cylindrical magnets (not shown) of opposite polarity each fill the two grooves 102, 104 and form a plasma track between them. The groove 102 completely surrounds the groove 104. The two grooves 102 and 104 are arranged at a track pitch Q and are separated from each other by a mesa 108 having a substantially constant width. From the above description, the mesa 108 represents the gap between the counter electrodes. One groove 102 represents the outer magnetic pole. The other groove 104 represents the inner magnetic pole surrounded by the outer magnetic pole. Similar to the racetrack magnetron, one magnetic pole, represented by groove 104, whether twisted or not, is completely surrounded by the other magnetic pole, represented by groove 102. This intensifies the magnetic field and forms one or more plasma loops to prevent edge losses. The width of the outermost portion of the groove 102 is slightly larger than half the width of the inner portion of the groove 102 and all the portions of the other groove 104. This is because the outermost portion accommodates only one row of magnets, and the other groove portion accommodates two rows in a staggered arrangement. The grooves 102, 104 of the magnetron 100 may be modified to include a tail portion around the 180 ° curved end 110 of the mesa 108, similar to the tail portion 82 of FIG. A single magnetic yoke plate may cover the back of the magnetron plate 106 and magnetically couple all the magnets.

  The rectangular spiral magnetron has grooves 102, 104, and straight sections that, when fitted with magnets, have magnetic poles, extend along the vertical direction and are connected to each other by curved corners. The straight portion is preferably at least 50%, more preferably 75% of the total length of the pattern.

  The grooves 102, 104 typically represent two magnetic poles that define a plasma track between them. However, the structure is more complex. In this embodiment, the grooves 102, 104 are machined into, for example, an aluminum non-magnetic magnetron plate 42 to include an array of cylindrical holes or serrated ends, so that they are separate cylindrical permanent magnets in a close-packed configuration. To capture. The cylindrical holes in the thick portions of the grooves 102, 104 may form parallel rows extending in two staggered lines to increase the magnet packing density. On the other hand, the outer portions of the grooves 102, 104 may have only one such linear array. Typically, two optional pole pieces formed of magnetically soft stainless steel have the shape of the grooves 102, 104 and approximate width. An optional pole piece is screwed to the bottom of the magnetron plate above the grooves 102, 104 to capture both the magnets in the lower facing grooves 102, 104 and act as pole pieces. However, the magnetic yoke plate may provide a sufficient holding force so that neither pole pieces nor screwing means are required. This will be described later with respect to a nonmagnetic retainer for arranging magnets.

  The number of raps or folds can be greatly increased. Other convoluted shapes for the magnetron are possible. For example, serpentine and helical magnetrons can be combined in different ways. A helical magnetron may be coupled to the serpentine magnetron. Both are formed by a single plasma loop. Two helical magnetrons may be joined together, eg, with opposite twists. Two helical magnetrons may surround the serpentine magnetron. Typically, a single plasma loop is desirable. However, the advantages of the present invention are also enjoyed with multiple convoluted plasma loops.

  Although the rectangular helical magnetron 100 has been found to be effective, there is room for improvement in its uniformity. There are some problems. Cold spots, i.e., regions with slow deposition rates associated with the curved corner 112 of the gap 108, end regions near the curved outer end 110 of the plasma track, and concave regions near the outer end of the helical plasma loop with reduced magnetic field. There are 114. Furthermore, it has been observed that the central, generally rectangular region has reduced deposition relative to the large outer region. For the magnetron 100, several improvements are possible.

  The single helical magnetron 120 shown in the plan view of FIG. 9 and the enlarged plan view of the corner in FIG. 10 includes an outer magnetic pole 122 of one magnetic pole and an inner magnetic pole 124 of the other magnetic pole that surrounds it. There is a gap 126 having a substantially constant width. The structure shown is implemented as a swivel retainer structure of a pair of retainers. Briefly stated, the magnets are arranged in between and contain cylindrical magnets in one of two perpendicular magnetic poles along the hole axis. There are magnet holes or positions 128 to do so. The opposite magnets represent two opposite magnetic poles. A through hole 130 is opened in the retainer to receive a screw that secures the opposite pair of linear retainer 132 and curved retainer 134 to a magnetic plate acting as a magnetic yoke. The retainer structure can accommodate about 6000 magnets at the outer and inner poles 122, 124 and can create a convoluted plasma track with a length of more than 75m. However, it is not necessary to fill all holes or locations.

  First, magnets are arranged on the inner part in pairs along one line of the outer part of the outer magnetic pole 122 along the spiral path. Thereby, each plasma track corresponding to the gap 126 is surrounded between a number of opposite two rows of magnets substantially equal in number to the magnets for that track. However, the corners of the rectangular track are formed by separate curved retainers 134. At least inside the curved retainer 134 is an additional arc-shaped line of the hole 136 away from the gap 126 to accommodate not only the normal component of a single arc-shaped line of magnet holes, but also additional magnets. Is also formed. These additional magnets are to compensate for the reduction in deposition that would occur at the 90 ° corner. The location of these additional magnets is filled with a magnet of the same polarity as its magnetic pole that is required to obtain a uniform deposit.

  The overall structure forms a rectangularized helical plasma loop that is about 6-3 / 4 wraps, ie, much more than the less than 2 wraps of FIG. Each lap corresponds to two plasma tracks. It is preferably carried out at least over the length of the separation of the two-dimensional scanning needs, roughly two or many plasma tracks. An increase in the number of laps means that the scanning length can be reduced.

  The double helical magnetron 140 shown in the plan view of FIG. 11 and the enlarged plan view of the corner of FIG. 12 includes an outer magnetic pole 142 that surrounds the inner magnetic pole 144 and is separated by a gap 146 having a substantially constant width. Again, the illustrated structure includes a pair of retainers 132, 134 that are screwed to the magnetic base plate to hold multiple magnets. The location of the magnet indicates the magnetic pole. This figure does not show magnets mounted on the retainer double sawtooth structure, and in this embodiment, no additional corner magnet positions are shown. However, in this embodiment, the spiral wrap is implemented differently. First, the elongate linear plasma loop magnetron 24 of FIG. 2 is bent so that the two end portions 34 are close to each other on the side surface, and the middle of the axis of the magnetic poles 26 and 28 and the gap 30 are half of a wide radius. Make a bend at the circular end. In the configuration of FIG. 11, the rectangularized helix includes an outer end 150 having four adjacent generally parallel plasma tracks and an inner end 152 having two separate ends for the dual plasma track. . This structure has a large straight section with four parallel gaps 146 and produces four parallel plasma tracks. This 4-track structure is wrapped in the illustrated rectangularized helix with approximately 30 plasma tracks in the approximate center. Note that the curved linear magnetron of FIG. 2 wraps with the wide radius ends on the outside and the two short radius ends 30 on the inside. It is possible to wrap in other ways, but the center will not be very symmetric.

  Both magnetrons 120, 150 are still less deposited near the center of the magnetron, for example, the magnetron 156 illustrated in the plan view of FIG. 13 and the enlarged plan view of the corner of FIG. 14 is generally about 10% of the total magnetron region. Occupying a rectangular inner region 158, which reduces the sputter deposition rate. Disparate deposition can be reduced by using a strong cylindrical magnet within the less deposited interior region 158 than using magnets outside the region 158. If a cylindrical magnet, for example, a rare earth magnet of NdBFe has a magnetic strength of 38MgO, the overall deposition rate is sufficient. MgO represents Mega Gauss Oersted. Strong magnets are commercially available with a magnetic strength of 48 MgO, ie 26% stronger. Stronger magnets are available in limited quantities and are very expensive. When a 38MgO magnet is mounted on the main track of the magnetron 156 outside the low deposition internal region 158 and the 48MgO magnet is located inside the internal region 158, deposition uniformity is greatly improved, but not completely. .

  The serpentine magnetron 160 shown in the plan view of FIG. 15 and the enlarged plan view of FIG. 16 has a linear racetrack magnetron that is bent ten times. Its retainer structure is more regular than a helical magnetron. The outer retainer 161 and the inner retainer 162 are typically separated by a gap 163 associated with the plasma track, and as shown, a regular, generally straight line with two rows inside and one row at the two side edges. It has the arrangement of. The retainers 161, 162 also have a number of additional magnet positions 165 that are incorporated into the bent retainer at the long 180 ° bends of the gap 163 on either side of the 180 ° bends. The end of the stub retainer 166 associated with the outer pole has an additional magnet position 167 with a sharp 180 ° bend in the gap 163. In addition, an additional magnet position 168 is between the long 180 ° bend close to the two outer tops and the lower end of the magnetron 160, as shown.

  In particular, in spiral magnetrons, other than increasing the strength of the magnet in the central region 158, another way to increase the central deposition rate requires some understanding of the vertical structure of the magnetron. As shown in the cross-sectional view of FIG. 17, the magnetic magnetron or back plate 170 acts as a main support member for the movable magnetron and magnetic yoke. It is a thick plate, e.g. 1/2 "(12 mm) thick, made of soft magnetic material, i.e. steel, e.g. cold-rolled steel A36 or stainless steel. Non-magnetic retainer 172 is a non-magnetic screw. It is fixed to the lower part of the back plate 170 in its operating direction by 174. The retainer 172 may be made of aluminum (eg 6061 Al) or non-magnetic stainless steel or brass. The columnar magnets 176 and 178 are loosely fitted between two retainers 172 having a gap 180 therebetween, and are held by the magnetic back plate 170 by a strong magnetic force, and are held between the parallel retainers 172. The magnets 176 and 178 have opposite polarities and generate a magnetic field B beyond the gap 180 between the magnets 176 and 178. The corners 172, 174 need not be as thick as the length of the magnets 176, 178 that are held in. The pole pieces may be fixed on top of the magnets 176, 178, but are not required. If the magnets 176, 178 have opposite polarities as shown, the back plate 170 acts as a magnetic yoke, and the opposite magnets 176, 178 generate a magnetic field B. Non-magnetic retainer. Since 172 does not interfere with the magnetic field, the gap 180 between the opposite poles is considered the distance between the opposite polarity magnets 176, 178 in different lines The retainer 172 is typically more than the magnetic yoke 170. The advantage is that it is made of light material and can be designed and installed separately.

  The largest portion of magnetrons 120, 140, 156, 160 includes two adjacent alternating rows of magnets. As shown in the plan view of FIG. 18, the two linear retainers 190, 192 have opposing serrated or scalloped ends, and an arcuate pocket 194 with a slightly larger radius than the magnet 194 is retained in them. ing. A non-magnetic screw 196 holds the retainers 190, 192 on the back plate 170, and the pockets 194 are axially offset from each other at half the diameter of the magnet and have space to accommodate the two closest rows of magnets 198. .

  The outer portion of the outer pole is typically filled with a row of magnets. These external portion linear retainers 190, 192 can have a similar sawtooth design but are secured to the backplate 170. The pockets 194 are side-by-side with a space for capturing a row of magnets 198. The corner section connecting the straight sections includes a curved portion, which bends one or two rows of magnets 90 °. The corner section may include a similar retainer, but the curved portion has a different radius. The corner sections are individually manufactured and screwed to the back plate 170 side by side with adjacent linear retainers 190, 192.

  As illustrated in the cross-sectional view of FIG. 19, another method of increasing central deposition is to use a shim 200 of magnetic material, such as cold rolled steel, as described above, with a backplate facing the target in the central region 158 that exhibits a low deposition rate. The thickness of the shim is in the range of 2 to 8 mm, for example, 5 mm, and the surface height is efficiently increased. When the retainer is screwed to the shim 190 directly in the central region 158 to the back plate 170 outside the central region 158, the height of the magnet 202 held by the retainer is effectively increased in the low deposition central region 158, For magnets 204 held outside area 158, they are brought close to the target. Thus, the magnetic field is increased at the target close to the central region 158 to increase the plasma density and sputtering rate. If desired, a thinner, eg 2 mm, transition shim 206 is secured to the back plate 170 around the central shim 200 and a magnet retainer is further secured to the transition shim 206 to hold the magnets 202 at different heights, The transition between 204 may be facilitated and deposition uniformity may be improved. Alternatively, the transition shim 206 is below the main shim 200 but may extend laterally beyond that. An additional peripheral shim may be used, or a shim having a combined outer shape may be machined to form a shim. It is also possible to machine the outer shape to form the back plate 170. However, using one or more shims enhances flexibility.

  Returning to FIG. 13, the above-described magnetron focuses on straight portions parallel to the sides of the rectangular magnetron in order to increase uniformity. The straight portions are connected by curved portions or corners 210, which are generally located at the two diagonals of the rectangular magnetron, details of which are illustrated in FIG. The corners generally have the same very small radius. As a result, the gap width between the opposite magnets increases within the curved portion of the corner 210, reducing the magnetic field protruding in front of the target and reducing the sputtering rate. A few or many additional magnets may be placed in additional holes 136 formed in the curved retainer 134 to compensate for the reduced magnetic field at the corner 210. The corner 210 may need to be adjusted not only in the development of the apparatus, but also when the machine is applied to different sputtering materials and sputtering conditions. In other words, the corner 210 needs a lot of adjustment both in the development laboratory and on site.

  The back plate 170 is a large and very heavy piece. Once manufactured and shipped at the machine shop, the development lab is designed not only by adjusting the number of magnets, but also by designing new retainers and shims that can be machined cheaper, shipped more easily and installed on site Or it is desirable to make corrections on site. For example, FIGS. 20-22 illustrate a linear retainer 220 with pockets 222 aligned with each other to accommodate a row of magnets in this example. However, in other embodiments, a plurality of rows of magnets may be included. The screw 196 fixes the linear retainer 220 at a predetermined position on the back plate 170. The vertically extending linear retainer 220 is connected by an inner corner retainer 224 and an outer corner retainer 226, which are also designed to accommodate a single row of magnets. The three sets of corner retainers 224, 226 illustrated in the different figures of FIGS. 20-22 include curved portions of different radii and straight portions that have a reduced range between the three embodiments. However, the ends are similarly arranged with each other, and the screw holes of the screws 196 of both corner retainers 224, 226 and the back plate 170 are similarly arranged in all three embodiments. As a result, in order to adjust the magnetic field distribution at the corners of the magnetron, it is only necessary to replace the different sets of corner retainers 224, 226 with existing sets of screw holes drilled in the back plate 170.

The magnetic field strength can be increased by using a high strength magnet at the corner and a low strength magnet at the straight portion.
Two row corners are illustrated in the plan view of FIG. It has two vertical sets of linear retainers 230, 232 that are connected at the corners by an outer corner retainer 234 and an inner corner retainer 236. The pockets of the linear retainers 230, 232 accommodate the two closest rows of cylindrical magnets 238 in an alternating fashion. The corner retainers 234, 236 are arranged to also accommodate two curved rows of magnets 238 that are as dense as the curvature allows. The corner retainers 234, 236 have different curvatures and are easily exchanged for other corner retainers 234, 236 with short or long straight sections.

  It is a further feature that the corner retainers 234, 236 may also have auxiliary magnet holes 240, 242 inside and outside the two rows of magnets 238. As required to optimize the magnetic field distribution at the corner, an auxiliary magnet may be placed in one or more of the auxiliary magnet holes 240, 242 to increase the magnetic field strength at the corner. Auxiliary magnet holes 240, 242 may also be formed in the row of corner retainers 234, 236 of FIGS.

  Additional features are illustrated in FIG. If the exact location of the screw hole for the screw 196 is selected to satisfy both two opposite directions, the pair of linear retainers 230, 232 are inverted around their longitudinal axis to create a straight line Retainers 230 ', 232' can be formed, with a series of rectangular or bar magnets 248 polarized perpendicular to the plane of the figure with the serrated end 244 facing outward and the flat end 246 facing inward. Accommodate. The bar magnet 248 can provide a large magnetic field strength due to a single fill factor. Of course, special linear retainers having only flat ends may be designed.

  The serpentine magnetrons 60, 80, 160 have a single main set of straight sections 220, 222, mostly connected by 180 ° curved sections, and the rectangular spiral magnetrons 100, 120, 140, 156 are: It has two sets of parallel straight sections 220, 222. Both are considered the main set connected mostly by 90 ° curved sections 204, 206 or 234, 236. All magnetrons benefit from a one-dimensional scan beyond pitch P, transverse to one of the main sets of straight sections. However, such one-dimensional scanning still has drawbacks. First, the sputtering uniformity is greatly impaired. This is because most of the magnetron extends in a direction having components parallel to the scanning direction. The effect is most noticeable in a rectangular spiral magnetron where the straight section extends along the scanning direction and has a large non-uniformity in the direction transverse to the scanning direction. Even in a serpentine magnetron, high magnetic density tends to occur in the region of the 180 ° curved section, causing the side edges of the target to erode faster than the central portion of the target. These magnetrons also erode the central part of the target, but less than the sides. Second, if no other precautions are taken, all magnetrons will continue to create plasma near the side edges of the target near the plasma shield. As previously described in the Linear Racetrack Magnetron, close proximity greatly increases particle generation during plasma ignition. Third, when magnetrons are scanned immediately and with respect to each other, end erosion results in excessive erosion.

  Sputtering uniformity can be increased by scanning a convoluted magnetron in two orthogonal directions for a rectangular target. The scanning mechanism can assume different forms depending on the complexity of the desired scanning pattern. In the scanning mechanism 260 shown in FIG. 24, the target 16 supports a magnetron plate 262 including a magnet on the back side and on the upper side through a plurality of insulating pads 264 or roller bearings held in holes at the bottom of the magnetron plate 262. is doing. If the pad 264 is such, it is composed of Teflon plastic (a registered trademark of DuPont) or other soft polymer material, with a diameter of 5 cm and protruding 2 mm from the magnetron plate 262. Yes. An opposing push rod 266 driven by an external drive source 268 passes through the vacuum seal back wall 22 and through the coupler 270 in the opposite direction from the magnetron plate 262. For two-dimensional scanning, the coupler 270 may be formed with rotatable wheels that selectively and smoothly push the magnetron plate 262. However, a soft Teflon pad is sufficient. The power source 268 is typically a bi-directional rotary motor that drives a drive shaft having a rotational seal with respect to the rear wall 22. A lead screw mechanism inside the rear wall 22 converts rotational motion into linear motion. Alternatively, the lead screw mechanism may be external to the sealed rear wall 22 and coupled to the push rod 266 through the rear wall 22 by a sealed bellows assembly. Two pairs of push rods 266 and power source 268 arranged vertically provide independent two-dimensional scanning. A pair of push rods 266 and a power source 268 diagonally along the target provide a coupled two-dimensional scan for the sides of the target. Other types of actuators are possible, including pneumatic cylinders, stepping motors, and rack and pinions, both inside and outside the low pressure back chamber.

  In another embodiment illustrated in the plan view of FIG. 25, the spring 272, preferably the illustrated compression spring, may be replaced with an opposing push rod 266 for push drive force. Also, the coupler 274 is secured between the push rod 266 and the magnetron plate 262 so that a single rod 266 pushes or pulls the magnetron plate 262 against the spring 262, preferably a tension spring. Can do. To implement a diagonal scan pattern, the convoluted magnetron formed on the magnetron plate 262, illustrated in the plan view of FIG. 25, is supported within a rectangular frame 276 that forms the rear wall 22 portion. Although a serpentine magnetron is illustrated, other magnetron shapes may be used. A fixed coupler 274 drives an actuator 268 coupled to the magnetron plate 262 along the diagonal of the frame 276, ie, from northwest to southeast. This is both parallel and transverse to the direction of the main set of linear portions of the magnetron. In the illustrated embodiment, the spring 272 reacts with the actuator 268. As a result of the diagonal scan, hypererosion on the north and south sides of the target is reduced.

  With the plasma on, along the diagonal of the frame or along one of its principal axes, the scan is extended to the front-rear scan and the magnetron is returned to its original position to prepare the next panel for sputtering. can do. Alternatively, a back scan can be performed with the plasma turned off, a new panel placed in the sputter reactor, and the sputter chamber pumped down to equilibrate. In a further variation, the first panel can be sputter deposited during the forward scan and the next panel can be deposited during the subsequent back scan.

  Other types of scanning mechanisms are possible. The sliding pad 264 can be replaced with wheels, rolling or roller bearings. US patent application Ser. No. 11 / 347,677, filed Feb. 3, 2006, Inagawa et al., Which is incorporated herein by reference. The wheels, rolling or roller bearings are preferably electrically isolated, grounded to the magnetron plate 262 and supported by the biased target 16. For simple movements, a guide plate intermediate the magnetron plate 262 and the target 16 guides the scan. As described in the Halsey patent mentioned above, the magnetron plate 262 may be supported from above through the wheels and support rods by one or more guide plates.

  The range of scanning is relatively limited. The scanning length is preferably at least the pitch between adjacent plasma tracks and is approximately equal to or several times the pitch. For example, for a relatively small number of fold or lap magnetrons designed for a 2 m target with a pitch between adjacent non-parallel tracks of 75 mm, the scan distance should be at least 75 mm. For many fold or wrap magnetrons, eg, magnetrons 120, 140, 156, 160, the scanning distance can be reduced. In order to make the magnet strength and position variable, it is recommended that the scanning distance be at least 10 mm longer than the pitch of the plasma track. If the scanning distance is 50% or more longer than the pitch, the advantage of the present invention is impaired. Experiments have shown that excellent erosion is provided at a scanning distance of 85-100 mm. A pitch of 75 mm between the magnet grooves, that is, between the plasma tracks has proved to be very effective, and a preferred range of 50 to 125 mm is indicated for the pitch. In a convoluted magnetron, the required scan length decreases as the number of wraps and folds increases.

  Scanning has the advantage of two operational features. The first is advantageous because the scan can be performed at a relatively slow rate of about 1 mm / s, and complete deposition can be achieved with a single scan of the frame diagonal, or several such diagonal scans as described below To be implemented. Very good results have been obtained at a scanning speed of 2 mm / s, the preferred range being 0.5-5 mm / s. For a 100 mm scan, a full scan can be performed in 20-200 s. Low speed simplifies heavy mechanisms. Second, after the plasma is extinguished, a slow scan is started and the magnetron strikes the plasma after the initial scan of 2 mm, preferably 1-5 mm, for example, after the magnetron has come off very close to the grounded frame 276. It is advantageous. When striking is delayed, the scanning speed can be balanced. Importantly, however, striking away from the frame 266 significantly reduces particle generation, which is believed to result from uncontrolled arcing during plasma striking.

  Experiments were performed and a linear racetrack magnetron was scanned across the frame with a constant power source. Observing the target voltage, as shown by the plot 278 in the graph of FIG. 26, it rises from about 500V in the middle to about 600V near the frame 276 or shield, indicating the dependence of plasma impedance on the magnetron position. This high voltage near the frame is thought to be the result of electrons leaking into the frame 276 and is associated with excessive arcing during striking. Instead, arcing is greatly reduced when the plasma is striked on a flat portion of the curve. It is also advantageous to extinguish the plasma before the magnetron reaches the other diagonal corner. As is well known, the strike and extinguishment of the plasma are mainly performed by raising and lowering the power applied to the sputtering target, respectively. Furthermore, if the deposition is performed on the same substrate, the target power can be reduced to obtain a low density plasma rather than completely extinguishing the plasma, thereby significantly generating particles at the target edge. Reduce to. The same variation in voltage may be applied to a scan perpendicular to the side of the frame 276. Reduce voltage or extinguish plasma near frame 276.

  It has also been observed that the target voltage in the rectangular spiral magnetron 100 of FIG. 8 is only about 350V, indicating a very efficient magnetron.

  With the magnetron 280 shown in FIG. 27, the same effect as the diagonal scanning mechanism of FIG. 25 can be obtained. With respect to the rectangular configuration of the frame 276, a magnetron plate 262 is formed with one or two main sets of straight sections 282 formed at an inclined angle, for example 45 ° or parallel to the frame diagonal. ing. The effect of a diagonally arranged magnetron is most apparent in the serpentine magnetron shown, but a rectangularized helix with straight sections arranged at complementary tilt angles for side and uniaxial movement of the frame The same effect can be obtained with a magnetron. Opposite actuators 268 aligned along one of the two rectangular configurations scan the magnetron plate 262 along that configuration. In this embodiment, the scan is one dimensional, but the magnetron shape is clearly two dimensional with respect to the frame 276. In order to eliminate the edge effects during striking, additional target space must be provided along the sides.

  The scanning along two diagonals can be performed by the scanning mechanism 290 illustrated in the schematic plan view of FIG. Four actuators 268 are arranged in opposite pairs along two frame diagonals. Each actuator 268 is secured to one of the corner push rods 266. The corner bracket 292 connected to the end of the push rod 266 has two vertical arms 294, each having a plurality of wheels 296 or other sliding means, each corner of the magnetron plate 262 being Engage smoothly, line up, and push it exactly along one of the frame diagonals. Although a serpentine magnetron is illustrated, other convoluted magnetron shapes may be used for this and other two-dimensional scanning mechanisms. A scan along any diagonal requires only one of the actuators 268. The scan moves from one diagonal to the other. This is done by pushing the magnetron plate 262 along the first diagonal to the center point through which the second diagonal passes by one of the actuators aligned with the first diagonal. Thereafter, one of the actuators 268 aligned with the second diagonal engages the magnetron plate 262 and pushes it along the second diagonal.

  The rectangular arrangement scanning mechanism 300 shown in FIG. 29 includes eight actuators 268, which are arranged in pairs along the four sides of the rectangular frame 276 and are arranged at the end of the push rod 266. Each part has a wheel 302 or other rotating member, and the vertical frame side is engaged at the corner. A soft push pad, such as that of Teflon, may be substituted for the wheel 302. Paired actuators 268 are controlled in the same manner to extend the associated push rod 266 in the same manner. When there is no fixed connecting portion between the actuator 268 and the magnetron plate 262 and only a pressing force is generated, it is preferable to make a pair. Only one pair of wheeled actuator push rod 266 needs to engage the magnetron plate 262 and move it along the Cartesian direction.

  The other overhead scanning and support mechanism 310 illustrated in orthographic projection in FIG. 30 is supported by a frame 276, which is supported around the target backing plate. The cooling manifold 312 distributes cooling fluid from the supply line 314 to the target backing plate. The corresponding drain manifold and drain line on the opposite side are not shown. Tanase et al. Describe an improved cooling backing plate and manifold in patent application 11 / 190,389, filed July 27, 2005, which is incorporated herein by reference. The Tanase cooling plate has a cooling hole that opens to the side of the integrated backing plate, and a cooling liquid manifold is arranged in a plane to form a counterflowing cooling liquid on the plate. Yes. The Tanase reference also teaches that a generally rectangular multi-tile target may have corners that follow the outer plasma track. The slider plate 320 includes two opposite side rails 322, 324 and slides along a series of wheel bearings mounted on the frame 276 at the top thereof in a first direction. Two slots 326, 328 are formed in the slider plate 320 and extend in a second vertical direction. Two reverse rails 330, 332 fixed to and supporting the magnetron plate 170 extend through two slots 326, 328 and are slidable on a series of wheel bearings mounted on the slider plate 320. It is supported and can move in the second direction. That is, the magnetron plate 170 and associated magnetron can slide in vertical first and second directions. In addition, the heavy magnetron is supported by the frame 276 and the target backing plate, which itself is directly supported by the chamber walls and not by the relatively thin inner part of the target and target backing plate. US patent application Ser. No. 11 / 347,667, filed Feb. 3, 2006, which is incorporated herein by reference, Inagawa et al. Discloses a suspension system in which a magnetron plate 170 is Partly supported by the rails 330, 332 through the springs and partly on the target backing plate through the rollers. That is, the Inagawa system combines the features of FIGS.

  Along the direction of the slider rail 322, opposite first sets of actuators 334, 336 are supported by the frame 276 and drive independently controlled bidirectional motors 338, 340 and push rod 344, respectively. A worm gear 342 is included. Accordingly, the bosses 346 and 348 extending upward from the slider plate 320 are selectively adjacent to and engaged with each of the bosses 346 and 348 to selectively apply a force. Along the direction of the magnetron plate rails 330, 332, opposite second sets of similarly configured actuators 352, 354 are supported by the frame 276. Accordingly, the bosses 356 and 358 that are fixed to the magnetron plate 170 and extend upward on the slider plate 320 and pass through the windows 360 and 362 are selectively engaged. The windows 360, 362 are much larger in size than the associated bosses 356, 358, allowing the bosses 356, 358 to move the full scan distance in two orthogonal directions.

  The opposite pair of actuators 334, 336, 352, 354 can be used to move the magnetron plate 170 and attach the magnets in the orthogonal direction. The bosses 356, 358 secured to the magnetron plate 170 have a relatively wide surface 364 so that when another set of actuators 334, 336 moves the magnetron plate 170 laterally, the associated actuator 352, The push rods 344 of 354 allow slidable engagement therewith.

  Still another scanning and support mechanism 370 illustrated in the exploded orthographic view of FIG. 31 is an improvement over FIG. 30 and is more fully illustrated. Frame 276 supports two rows of rollers 372 on the opposite side of the frame. These movably support the opposite frame rails 322, 324 that support the gantry 374 between them. The gantry 374 has an open lattice structure than the slider plate 320 of FIG. 30, but provides substantially the same function. The gantry 374 includes four rows of rollers (not shown) in the inner support members 376 and 378 and the outer support members 380 and 382. Four struts support the reverse gantry inner rails 384, 386 and outer rails 388, 390 in a rollable manner. The gantry rail partially supports a magnetron plate 170 that includes a magnet on its underside. The outer struts 380, 382 and the outer rails 388, 390 are optional but provide additional support at the sides of the heavy magnetron plate 170, closer to the end compared to the two rail supports of FIG. Reduce the amount of drooping. The bracket-shaped base plate 392 is fixed to a frame structure that forms the gantry 374.

  A magnet chamber roof 400 forming the upper wall of the back chamber 22 of FIG. 1 is supported and sealed by a frame 276 having a gantry structure therebetween, and provides a vacuum wall on top of the chamber containing the magnetron. . Magnet chamber roof 400 includes a rectangular aperture 402 and a lower portion of bracket recess 404. The bracket chamber 406 is fitted in the bracket recess 404 and is sealed to the chamber roof 400 around the rectangular aperture 404. The top plate 408 is sealed to the top of the bracket chamber 406 to complete the vacuum seal.

  A gantry bracket 410 movably disposed in the bracket chamber 406 is fixed to a base plate 392 of the gantry 374. Support bracket 401 and intermediate angle steel 414 secured to the exterior of magnet chamber roof 400 hold actuator assembly 416 in actuator recess 418 in roof 400 outside the vacuum seal. Support bracket 412 also acts as part of the truss system in magnet chamber roof 400. Actuator assembly 416 is coupled to the interior of bracket chamber 400 through two sealed vacuum ports.

  Actuator assembly 416 includes a belt having an end fixed to magnetron plate 170, independently moving gantry 374 in one direction by a force applied through gantry bracket 410 fixed to gantry base plate 392. The magnetron plate 170 is moved in the vertical direction by the belt drive.

  The actuator assembly 416 illustrated in the detailed orthographic view of FIG. 32 includes two actuators that are coupled to the interior of the bracket chamber 406 through two sealed ports including each bellows 420, 422. Yes. The bellows penetrates the side wall 424 of the bracket chamber 406 of FIG. Each of the bellows 420 and 422 is an integral tubular member that is corrugated in the axial direction, and has sufficient elasticity to expand along the actuator axis by the same distance as the scanning distance along the frame side rails 322 and 324. . Bellows 420, 422 have one end sealed around the aperture of side wall 424 and the other end with respective vacuum seal caps 426, 428.

  The actuator assembly 416 also illustrated from the opposite side of the orthographic view of FIG. 33 includes two actuators for two vertical movements. This view includes an actuator assembly 416 and a gantry 374 but does not include the intermediate magnet chamber roof 400. 32 and 33 both illustrate a plate structure for the gantry 374 rather than the frame structure of FIG.

  The linear actuator of actuator assembly 416 includes a first stepper motor 430, a gear box 432 and a worm gear 434. An actuator rod 436 driven in a straight line by the worm gear 434 is connected to the end cap 428 of the bellows 422. This is not hollow. The push rod 438 connected to the other end of the end cap 428 is fixed to the gantry bracket 410 by a screw fixing fixture 440. However, other straight vacuum ports are possible. For example, the lead screw mechanism can be incorporated into a lead nut and lead screw that rotates with the gantry bracket 410. The lead screw is formed at the end of the rotary output shaft of the first stepper motor 430 that passes through the rotary seal into the vacuum chamber.

  The rotary actuator of actuator assembly 416 includes a second stepper motor 444 that is supported on angle iron 414 through linear slide 446 and has a rotary output shaft 448. The shaft 448 passes through the other bellows 420 to the sealed bracket chamber side wall 424. Bellows 420 includes a rotational seal at its end cap 426 for the rotating shaft 448. The linear slide 446 moves the second stepper motor 444 and its output shaft 448 along the axis of the rotating shaft 448 relative to the roof 400 and the frame 276. Other means are possible for the vacuum port that conveys linear and rotational movement. The other end of the rotating shaft 448 is supported by a bearing 450 held by the gantry bracket 410. The rotating shaft 448 holds a toothed pulley or capstan 452 and is wrapped around a ribbed belt 454. Two pulleys or rollers 456, 458 rotatably supported by two supports 460, 462 mounted on the base pail 392 or on the magnetron plate 170 have belt 444 down and their two ends. Lead outward toward. They are fixed to two pedestals 450 and 452, respectively, and the pedestals 450 and 452 are fixed to the magnetron plate 170 and extend upward through the window 468 in the gantry 364. The belt structure can be replaced with other structures. For example, the pinion gear of the rotating shaft 438 may engage the toothed rack of the magnetron plate 170.

  When combined, the linear actuator moves the gantry 374 along the direction of the frame side rails 322, 324, and the rotary actuator moves the magnetron plate 170 perpendicular to the supports 376, 378, 380, 382 fixed to the gantry 374. Move along the direction facing.

  The scanning mechanism 370 of FIGS. 31-33 provides a fixed connection between the two actuators and the magnetron plate 170, requiring four or more actuators for full vertical motion, In contrast to the unidirectional or sliding connection or contact of the embodiments, each provides an independent vertical bidirectional movement.

  The sputter chamber of FIG. 1 is typically controlled by a computerized control system, not shown, operated according to a recipe set for processing a series of panels 14. The control system includes a DC power source that supplies power to the target 16, a vacuum pumping system that pumps the inside of the sputtering chamber 18 and the back chamber 22 to a desired low pressure, a slit valve that connects the chamber interior to the moving chamber, and a moving chamber interior. The robot controls the robot that moves the substrate 14 in and out of the sputtering chamber 18. The control system is further connected to the actuators of various embodiments and scans a large magnetron behind the target 16 in a desired two-dimensional pattern.

  Multiple actuators may be controlled in combination with providing the desired scan pattern. One mode of simultaneous operation follows the device specific diagonal scan of FIG. For example, from northwest to southeast. However, scanning from southwest to northeast is also possible. The second mode of operation is to perform a first diagonal scan 460 along a single diagonal direction and extinguish the plasma near the end of the diagonal scan 470 as illustrated in the map of FIG. (Or reduce target power) improves erosion uniformity by scanning a full double Z pattern. The plasma is then extinguished or reduced, and the magnetron is scanned near the target end along a linear path 472 parallel to the Cartesian coordinates. Next, a second diagonal scan 474 is performed along the other diagonal with the active plasma, but the plasma is extinguished near the end of the second diagonal scan 474. Finally, the plasma is extinguished and the magnetron is scanned back along a linear scan 476 that is non-parallel to Cartesian (rectangular) coordinates near the other target end. This pattern is called double Z. Note that the path shown extends only over the scan dimension, e.g., 75 or 100 mm, and does not extend over the entire target with sides about 10 times larger. That is, the magnetron has an effective magnetic field that extends in a region with sides that are 80% or 90% or more of the corresponding dimensions of the target in the frame. Referring to the serpentine magnetrons 60, 80 of FIGS. 5 and 6, a double Z scan is performed and the end scans 472, 476 are performed either parallel to or perpendicular to the main set of straight sections 68. be able to. For helical wrap magnetrons, the end selection is not so important.

  Double Z scanning can be performed on a single substrate. Alternatively, a new substrate can be replaced during each of the rectangular scans 472, 476 without exciting the plasma, and the chamber pressure and gaseous ambient are relatively unimportant. The size of the double Z pattern is small enough that if the end effect is eliminated in the end passes 472, 476 in the presence of the plasma, an advantageous scan pattern is initiated at the center where the plasma is ignited. The While scanning the magnetron through a complete double Z pattern, the plasma remains ignited and eventually ends back to the center. Plasma ignition thus occurs at the maximum distance from any part of the grounded frame 276.

  Double Z scans and other types of scans do not need to be repeated exactly from one step to the next. The target erosion non-uniformity that determines the life of the target can be improved by replacing the double Z scan of FIG. 34 with the rotating double Z scan illustrated in the map of FIG. It also has two diagonal scans 480, 484 and two linear scans 482, 486, but the double Z pattern is rotated 90 ° from the double Z pattern of FIG. In particular, during the linear scans 482, 486, when the plasma is ignited, the rotating double Z scan erodes the portion of the target that was not efficiently scanned in the first double Z scan of FIG.

  Target erosion uniformity can also be improved by offsetting successive double Z scans in one or two directions. For example, as illustrated in the map of FIG. 36, after a first baseline double Z scan with diagonal scans 490, 492 and end scans 494, 496, the pattern is along a short distance, eg, 10 mm, Cartesian coordinates. Move. This is preferably perpendicular to the end scans 494, 496 for the execution of the second double Z scan 498. The range of the offset is 5 to 15 mm, preferably 8 to 12 mm. For the execution of the third double Z-scan 500, more uniformity is obtained by equal movement in the opposite direction from the baseline scan. Thereafter, the scan pattern may be returned to the baseline scan. Additional offset values may be used. Various portions of the full scan may be performed for deposition on a single substrate or multiple consecutively inserted substrates. A single full double Z scan is advantageously performed with sputter deposition on a single substrate, and a later transferred double Z scan is performed on the subsequent substrate.

  Double Z-scan movement may be performed in two directions as illustrated in the maps shown following FIGS. The exact sequence is not critical, but the first double Z-scan 510 of FIG. 37 includes the usable point closest to the southwest corner and does not extend to the eastern usable region. . The second double Z scan 512 of FIG. 38 is moving towards the east and includes the usable point closest to the southeast corner. In one method of sputtering, double Z scans 510, 512 are used for each single panel that is sputter coated. Returning to FIG. 37, the third double Z scan 514 is moving north from the first double Z scan 510. For example, the second scan 514 may move a distance Z from the first scan 510 in the x direction, and the third scan 514 may move the same or different distance Z from the first scan 510 in the y direction. Good. This process is repeated 4 times, 5 times, 6 times, for double Z scans 516, 518, 520. This process may continue for additional double Z scans, eg, a total of 10 scans, until the closest usable point in both northwest and northeast has been scanned. It is possible to move more than three times from west to east.

  A single double Z scan takes about 1 minute, which is sufficient to sputter the layer to a thickness of, for example, 1 μm. However, some layers need to be deposited to a thinner thickness. In particular, for short deposition times, one advantageous scanning pattern is the serpentine pattern of FIG. The first linear scan 530 extends along one side of the total scan area between the two opposite sides, during which the plasma is turned on and sputter deposition occurs. The first linear scan 530 may be short enough to sputter coat the required thickness for the first panel. The scan moves vertically in the first vertical scan 532 along the second side of the total scan area, which is perpendicular to the first side. The vertical scan 532 is performed while the plasma is extinguished and the first panel is replaced with the second panel in the sputtering chamber. Next, a second linear scan 534 that is non-parallel to the first linear scan 530 is performed with the plasma on, and a second panel having the same thin layer of sputtered material is sputter coated. While moving the scan back in the vertical direction, the plasma is turned off and the second panel is replaced with a third panel in the sputter chamber. This process continues until there is no useful scan area. This process is repeated either from the first point or in a reverse direction or other similar scan pass, including exchanging the direction of the straight and vertical scans, canceling the previous scan.

  The simple Cartesian scan pattern illustrated in the map of FIG. 40 follows a closed rectangular pattern with four sides 540, 542, 544, 546 with 90 ° corners between them, called the O-pattern. When used simultaneously with a serpentine magnetron having a long section arranged parallel to the east and west sides 542, 546, the plasma is turned off while scanning the east and west sides 542, 546, while scanning the north and south sides 540, 546, It is advantageous to turn it on. Alternatively, the plasma may be excited to a higher intensity when scanning the north and south sides 540, 544 and to a lower intensity when scanning the east and west sides 542, 546. This type of different power supply gives the panel a fairly uniform deposition pattern and more uniform erosion of the target.

  Two vertically arranged actuators can be activated simultaneously to move the magnetron along a diagonal path 550 illustrated in FIG. However, in some cases, it is preferable to follow a zigzag path instead. The zigzag path consists of small movements 552 along Cartesian coordinates and alternating small movements 554 arranged perpendicular to the Cartesian coordinates along the other. For example, each movement 552, 554 is about 1 mm. The range of the length of the movements 552, 554 is 0.4-3 mm, preferably 0.8-1.2 mm. If the diagonal path 550 is not positioned at 45 ° with respect to Cartesian coordinates, the movements 552, 554 are different in length between them and approach the diagonal scan 550. For example, if it is difficult to give the stepper motor an accurate ratio of vertical movement, different movements in the same direction will have different lengths and, on average, produce a whole path 550 in the desired direction. . This alternating movement provides a wide effective scanning area and increases sputtering uniformity. The alternating movement is further advantageous in the case of the vertically arranged push-in actuator of FIG. In this case, due to simultaneous movement in the vertical direction, at least one of the rod contacts slides relative to the magnetron plate, boss or gantry bracket. In contrast, alternating movement allows unused actuators to be retracted from the magnetron plate so that they do not contact the magnetron plate as they pass by the sides.

  In the case of a full set actuator, depending on the case, a more complicated substantially indefinite scan pattern including a curved portion is possible. For example, the number 8 scan 560 shown in FIG. 42 is obtained by successively changing the control of four sets of push actuators or two bidirectional actuators operated in the lateral direction. A scan 560 of numeral 8 is an example showing a substantially indefinite scan pattern obtained by the present invention.

  Experiments have shown that a rectangular target can be substantially uniform over a central region that extends to within 150 mm of the frame. Uniformity in one direction is increased by increasing the length of the straight portion of the serpentine magnetron, and uniformity in the other direction is increased by scanning the magnetron.

  In the described embodiment, a single scannable magnetron was used, but many aspects of both the scanning device and the scan pattern, each of which can be scanned separately and large portions independently. It may be applied to a sputter reactor having In particular, the usefulness of the target can be increased for many different forms of magnetrons. Similarly, the present invention may be applied to magnetron assemblies having multiple separate magnetrons that are scanned in conjunction. Split magnetrons are particularly useful when the target is split into strips with gaps in between and containing anodes or external cathode electrodes, or adjacent strips with DC or AC power being biased differently It is. Le et al. Describe a number of individually movable magnetrons in flat panel sputtering in US patent application Ser. No. 11 / 146,762, filed Jun. 6, 2005, incorporated herein by reference. .

  Many of the advantages of the present invention can be achieved when two-dimensional scanning or delayed plasma ignition is applied to conventional magnetrons. The conventional magnetron is composed of a plurality of parallel but independent linear magnetrons 24 of FIG. 2 and is formed of a plurality of parallel inner magnetic poles 26 all surrounded by a single outer magnetic pole 32. There are also a plurality of parallel openings for the inner pole 26 and each plasma loop. However, the serpentine and helical magnetron convoluted single plasma loops of the present invention are believed to provide more efficient and controllable sputtering.

  Different aspects of the present invention provide more uniform target erosion and sputter deposition with very large rectangular sputter targets. A convoluted magnetron can be obtained with little increase in cost. Two-dimensional scanning adds complexity to the scanning mechanism, but particularly with large magnetrons, slow scanning along the reduced scan length reduces the volume and cost of the scanning mechanism.

1 is a schematic side view of a conventional plasma sputter reactor configured to sputter deposit on a rectangular flat panel. FIG. FIG. 2 is a plan view of a conventional linear racetrack magnetron useful for the sputter reactor of FIG. 1. 1 is a schematic plan view of a serpentine magnetron according to an aspect of the present invention. It is a schematic plan view of the rectangular spiral magnetron of the present invention. It is a more practical plan view of a meandering magnetron. FIG. 6 is a plan view of an improved serpentine magnetron. It is a top view of the deformation | transformation embodiment of a meandering magnetron. It is a more realistic top view of a rectangular spiral magnetron. 1 is a plan view of a helical magnetron with multiple wraps and built-in retainers. FIG. FIG. 10 is an enlarged plan view of a corner of the magnetron of FIG. 9. It is a top view of a double wrap helical magnetron. FIG. 12 is an enlarged plan view of a corner of the magnetron of FIG. 11. FIG. 2 is a plan view of a helical magnetron showing a region with reduced deposition. FIG. 14 is an enlarged plan view of a corner of the magnetron of FIG. 13 including additional magnet holes. It is a top view of a large meandering magnetron. FIG. 15 is an enlarged plan view of a corner of the magnetron of FIG. 14 including additional magnet holes at various locations. It is sectional drawing of the retainer used for catching a cylindrical magnet. FIG. 5 is a plan view of a retainer that is screwed to a magnetic back plate and captures a magnet that forms a magnetron. 2 is a cross-sectional view of a magnetron incorporating shims to improve deposition uniformity. FIG. ~ FIG. 6 is a plan view of an interchangeable corner retainer with different radii. It is a top view of the retainer which captures two rows of cylindrical magnets and also captures bar magnets. It is a front view of the linear scanning mechanism which has the magnetron supported by the target so that sliding was possible. It is a top view of a diagonal scanning mechanism. It is a graph which shows the fluctuation | variation of the target voltage by a scanning position. FIG. 6 is a plan view of a linear scanning mechanism combined with a tilted magnetron that provides some results of diagonal scanning. It is a top view of 1st Embodiment of a two-dimensional scanning mechanism. It is a top view of 2nd Embodiment of a two-dimensional scanning mechanism. It is an orthographic view of the third embodiment of the two-dimensional scanning mechanism and the support structure of the magnetron. It is an exploded orthographic view of a fourth embodiment of a two-dimensional scanning mechanism. ~ FIG. 32 is a detailed orthographic view of an actuator portion of the scanning mechanism of FIG. 31. 2 is a map of a double Z scan path. FIG. 35 is a map of another double Z scan pass that is rotated 90 degrees from FIG. 34 and performed alternately. Fig. 6 is a path map for a sequence of offset double Z scans. ~ FIG. 6 includes a map of a path of a double Z-scan sequence offset in an orthogonal direction. It is a map of a meandering scanning path. It is a map of a rectangular scanning path. Fig. 3 is a map of a zigzag diagonal scan path. It is a map of the scanning path of number 8 as an example of a two-dimensional curved scanning path.

Claims (57)

  A sputtering magnetron on a surface having a substantially rectangular outer shape, the outer magnetic pole of one magnetic pole perpendicular to the surface, the inner magnetic pole of the other magnetic pole, and the inner magnetic pole surrounded by the outer magnetic pole, A sputtering magnetron in which the magnetic poles are arranged such that the gap forms a closed loop formed by three or more wraps around a point in the plane.   The magnetron according to claim 1, wherein a closed loop is formed by five or more times of the wrap.   The magnetron of claim 1, wherein the closed loop provides more than four tracks, which are traversed by a line radiating outward from the center of the magnetron.   The magnetron according to claim 1, wherein the loop is bent to form a bent loop, and the bent loop is wrapped around the point by two or more wraps.   5. The magnet according to claim 1, comprising magnets of opposite polarities forming the inner and outer magnetic poles, wherein the magnet in the central part of the magnetron is substantially stronger than the magnet in the outer part. Magnetron.   5. A scanning mechanism comprising a scanning mechanism that scans the magnetron in a two-dimensionally extending pattern over at least the same distance as the separation of parallel portions of the gap in the loop. The magnetron according to item 1.   The sputtering method implemented with the sputtering reactor containing the said magnetron of any one of Claims 1-4.   8. The method of claim 7, comprising scanning the magnetron over two perpendicularly extending patterns for at least the same distance as the separation of parallel portions of the gap in the loop.   The sputtering magnetron according to claim 1, wherein the magnetic pole is arranged such that the gap forms a closed loop formed by three or more spiral wraps around a point in the plane.   The magnetron according to claim 9, wherein the closed loop is formed by five or more times of the wrap.   The magnetron of claim 9, wherein the closed loop provides five or more plasma tracks, which are traversed by a line radiating outward from the center of the magnetron. A sputtering magnetron,
A ferromagnetic backplate;
At least two non-magnetic retainers provided with a convoluted gap formed therebetween to accommodate the magnet and secured to the back plate, wherein the gap is arranged in a convoluted pattern. Sputtering magnetron that forms a closed loop.   The magnetron of claim 12, wherein the wrapped closed loop is wrapped in a spiral pattern around a point in the backplate.   The magnetron according to claim 12, wherein the retainer is configured to accommodate both one row of columnar magnets and two rows of close-packed columnar magnets.   The magnetron according to claim 12, wherein the retainer includes a plurality of linear retainers extending along a vertical direction, and a corner retainer having a curved portion connecting the vertical linear retainers.   The magnetron according to claim 15, wherein the straight and corner retainers are detachably fixed to the holes of the back plate, and different configurations of the corner retainers can be detachably fixed to the holes.   A pair of the corner retainers can hold one or two rows of columnar magnets between each pair and can further hold at least one additional magnet radially inside or outside the one or two rows. The magnetron according to claim 16, wherein the magnetron is configured.   The magnetron of claim 16, wherein at least some of the corner retainers include at least one additional cylindrical hole for holding at least one magnet.   The sputtering method implemented with the sputtering reactor containing the said magnetron of any one of Claims 12-17.   20. The method of claim 19, comprising scanning the magnetron over two perpendicularly extending patterns for at least the same distance as the separation of parallel portions of the gap in the loop. A magnetron,
A ferromagnetic backplate;
A magnetron including a first ferromagnetic shim secured to a central region of the backplate to which a magnet of opposite polarity can be attached.   24. The magnetron of claim 23, comprising a non-magnetic retainer that holds the magnet and is secured to both the first shim and a portion of the back plate outside the shim.   The magnetron according to claim 21, wherein the central region is 10% to 40% of the region of the magnetron.   The magnetron of claim 21, further comprising a second shim thinner than the first shim disposed at least partially around the first shim.   The magnetron according to claim 21, wherein the magnet is cylindrical.   In a closed loop where the magnet is placed and twisted into a convoluted shape, a gap is formed between the opposite polarity magnet extending beyond the first shim region and the outer region of the first shim. The magnetron according to claim 21, wherein the magnetron is formed.   27. A sputtering method carried out in a sputtering reactor including the magnetron according to any one of claims 21 to 26.   28. The method of claim 27, comprising scanning the magnetron over two perpendicularly extending patterns for at least the same distance as the separation of parallel portions of the gap in the loop. In a plasma sputter reactor comprising a magnetron having a chamber, compatible with a rectangular target, sputtering the deposited material of the target onto a rectangular substrate and supported by a disposable support plate on the back of the target opposite the substrate The scanning mechanism
A gantry, supported on two opposite sidewalls of the chamber, slidable in a first direction, from which the magnetron plate is supported and in a second direction orthogonal to the first direction; A gantry configured to slide
A first actuator coupled to the gantry and moving it in the first direction;
And a second actuator coupled to the magnetron plate and moving it in the second direction. A first pair of rollers disposed in the first direction and supported on the two opposite side walls to movably support the gantry;
30. A scanning mechanism according to claim 29, comprising a second pair of rollers disposed in the second direction, supported by the gantry and movably supported by the magnetron plate.   30. The scanning mechanism of claim 29, wherein the first actuator also moves the second actuator in the first direction.   30. The scanning mechanism of claim 29, wherein the target, magnetron, and gantry are disposed inside the evacuated chamber and the actuator is disposed outside the chamber.   The output shaft of the first actuator is coupled through the chamber wall by a bellows assembly having a sealed end plate, and the output shaft of the second actuator includes a rotary seal at its end. The scanning mechanism of claim 32, wherein the scanning mechanism is coupled to the chamber through an assembly.   The output of the first actuator moves the gantry in a direction opposite to the first direction, and the second actuator moves the magnetron plate in a direction opposite to the second direction. 29. A scanning mechanism according to 29.   30. The scanning mechanism according to claim 29, wherein an output shaft of the first actuator is fixed to the gantry. A rotational output shaft of the second actuator;
A pulley fixed to the rotary output shaft;
30. The scanning mechanism of claim 29, further comprising: a belt having an end portion at least partially wrapped around the pulley and secured to the support plate.   37. The scanning mechanism according to claim 29, wherein the support plate is magnetic and acts as a magnetic yoke. In a plasma sputter reactor comprising a magnetron having a chamber, compatible with a rectangular target, sputtering the deposited material of the target onto a rectangular substrate and supported by a disposable support plate on the back of the target opposite the substrate The scanning mechanism
A first actuator fixedly connected to the support plate and moving it in a non-parallel first direction;
And a second actuator fixedly connected to the support plate and moving it in a non-parallel second direction perpendicular to the first direction.   The scanning mechanism according to claim 38, wherein the first and second actuators are operated independently.   39. The scanning mechanism according to claim 38, wherein the first actuator is a linear actuator, and the second actuator is a rotary actuator.   41. The scanning mechanism according to claim 40, wherein the second actuator is attached to a slider that is movable by the first actuator.   A method of sputtering a rectangular substrate, comprising scanning a magnetron on the back side of the sputtering target along a first two-dimensional multipart path having at least one straight portion.   43. The double Z path of claim 42, wherein the first path is a double Z path having two parallel portions and two intersecting portions connecting each pair of ends between the two parallel portions. Method.   43. The method of claim 42, wherein the second pass is a serpentine pass.   43. The method of claim 42, comprising scanning the magnetron at a back surface of the sputtering target along a second direction along a second direction that is offset from the first pass along a first direction.   Scanning the magnetron on the back side of the sputtering target along a second two direction perpendicular to the first direction and along a third two-dimensional multipart path offset from the first pass. 46. The method of claim 45, comprising.   A method of sputtering onto a rectangular substrate, comprising scanning a magnetron with a back surface of a substantially rectangular sputtering target along a path having straight portions that are non-parallel to each other.   48. The method of claim 47, wherein the magnetron is substantially rectangular and forms a closed plasma loop having a convoluted shape.   The magnetron is scanned in a double Z pattern along two opposite sides of the rectangle aligned with the target and along the diagonal connecting the ends of the two opposite sides 48. The method of claim 47.   50. The method of claim 49, wherein the magnetron is scanned with a plurality of double Z patterns offset from each other.   51. The method of claim 50, wherein the plurality of double Z patterns are offset from each other in a combination of orthogonal offsets.   The magnetron is scanned in a serpentine pattern, the serpentine pattern extending in a first direction substantially beyond a first scan distance, respectively, and the first scan 50. The method of claim 49, further comprising: a second portion extending in each of a second direction orthogonal to the second direction beyond a respective second scanning distance that is less than the distance.   A method of scanning a magnetron around the back surface of a substantially rectangular target, connecting two opposite sides parallel to the first end of the target and opposite ends of the two sides Moving the magnetron in a path having two diagonals.   A second having two opposite second sides perpendicular to the first end of the target and two second diagonals connecting the opposite ends of the two second sides. 54. The method of claim 53, comprising a second step of moving the magnetron around the back surface of the target in two passes.   55. The method of claim 54, comprising exciting a plasma proximate to the target during the first and second moving steps. A method of scanning a magnetron around the back of a substantially rectangular target, the target having side portions extending along first and second directions, respectively, arranged vertically,
A first step of scanning the magnetron in a first closed pass including first, second, third and fourth sections scanned in succession, wherein the first and third sections are Extending along a first direction, wherein the second and fourth sections are arranged diagonally with respect to the first and second directions, the first and third sections A first step of connecting ends arranged opposite to each other;
A second step of scanning the magnetron in a second closed pass including continuously scanned fifth, sixth, seventh and eighth sections, wherein the fifth and eighth sections are Extending along a second direction, wherein the sixth and eighth sections are arranged diagonally with respect to the first and second directions, the fifth and seventh sections A second step of connecting oppositely disposed ends.   57. The method of claim 56, wherein the first and second steps are alternately performed a plurality of times.

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