HYBRID CMP CONDITIONING HEAD

Abstract

In various implementations, a conditioning head includes a substrate comprising a substrate surface; and at least one raised non-planar abrasive region relative to the substrate surface. The non-planar abrasive region comprises an edge shaving region and a point cutting region, the ratio of the surface area of the edge shaving region to the point cutting region is at least 2:1; and wherein the cutting point region comprises one or more protrusions extending no more than 250 microns from the mean height of the edge shaving region

Claims

1. A conditioning head comprising: a substrate comprising a substrate surface; at least one vane, wherein the at least one vane comprises a non-planar abrasive region raised relative to the substrate surface, and wherein the at least one vane comprises: an edge shaving region; and a point cutting region; and wherein a ratio of a surface area of the edge shaving region to the point cutting region is at least approximately 2: approximately 1; and wherein the point cutting region comprises one or more protrusions extending no more than 250 microns from a mean height of the edge shaving region.

2. The conditioning head of claim 1, wherein the edge shaving region is coated with a CVD diamond layer.

3. The conditioning head of claim 1, wherein the point cutting region is positioned greater than 50% along a straight radial line starting from a central axis and ending at a peripheral edge of the conditioning head.

4. The conditioning head of claim 1, wherein the point cutting region is positioned greater than 90% along a radial line starting from a central axis and ending at a peripheral edge of the conditioning head.

5. The conditioning head of claim 1, wherein the point cutting region comprises one or more protrusions comprising CVD diamond coated diamond grit.

6. The conditioning head of claim 1, wherein the point cutting region and the edge shaving region comprises a polycrystalline diamond layer, the average grain size of the polycrystalline diamond on the point cutting region being greater than the average grain size of the polycrystalline diamond layer on the edge shaving region.

7. The conditioning head of claim 6, wherein the cutting point region is adjacent catalytic seeds disposed upon the substrate.

8. The conditioning head of claim 7, wherein the catalytic seeds comprise diamond, silicon, iron, cobalt, nickel and/or alumina.

9. The conditioning head of claim 1, wherein the one or more protrusions extend between 5 and 250 micron from the mean height of the edge shaving region.

10. The conditioning head of claim 1, wherein the one or more protrusions extend between 10 and 50 micron from the mean height of the edge shaving region.

11. The conditioning head of claim 1, wherein the one or more protrusions are rounded or convex.

12. The conditioning head of claim 1, wherein the one or more protrusions are non-geometric.

13. The conditioning head of claim 1, wherein the point cutting region comprising one or more isolated or clusters of protrusions.

14. The conditioning head of claim 1, wherein the ratio of the surface area of the edge shaving region to the point cutting region is at least 100:1.

15. The conditioning head of claim 1, wherein the ratio of the surface area of the edge shaving region to the point cutting region is at least 200:1.

16. The conditioning head of claim 1, wherein the raised non-planar abrasive region or R.sub.es comprises at least four radially extending vanes and between one and fifty protrusions, wherein each vane comprises between zero and five protrusions and said protrusion(s) are positioned greater than 70% along a radial line starting at the central axis and ending at the peripheral edge of the conditioning head.

17. A conditioning head comprising: a substrate comprising a substrate surface; at least vane, wherein the at least one vane comprises a non-planar abrasive region raised relative to the substrate surface, and wherein at least one of the vanes comprises: an edge shaving region; and a point cutting region; and wherein a ratio of a surface area of the edge shaving region to the point cutting region is at least approximately 2: approximately 1; and wherein the point cutting region comprises one or more protrusions extending no more than 250 microns from a mean height of the edge shaving region.

18. The conditioning head of claim 1, wherein the at least one vane comprises one or more discrete raised non-planar abrasive segments, and wherein the one or more segments comprises at least one of concentric circles, broken concentric circles, spirals, broken spirals segments, linear segments, broken linear segments, curved segments, or broken curved segments.

19. The conditioning head of claim 18, wherein the point cutting region is distributed across one or more of the segments.

20. The conditioning head of claim 18, wherein the point cutting region is distributed across less than 60% of the segments.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0073] FIGS. 1a and 1b are schematic diagrams of a cross section of a portion of the conditioner head, in accordance with one embodiment of the present invention.

[0074] FIGS. 2a to 2f are magnified optical images of a spiral vane surface on the conditioner head represented in FIGS. 1a and 1b.

[0075] FIG. 3a is an image of a diamond particle adhered to the substrate prior to diamond CVD. FIG. 3b is an image of FIG. 3a after diamond CVD.

[0076] FIG. 4 is a schematic diagram of the conditioner head of FIGS. 1a and 1b.

[0077] FIG. 5 is a topographic profile of a protrusion (cutting point region) and an adjacent edge shaving region.

[0078] FIGS. 6 to 10 are images and associated topography profiles of the surface of a portion of the conditioner head of FIG. 1a.

[0079] FIG. 11a to 11f are images of alternative raised non-planar edge shaving regions of conditioner head of the present invention.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE PRESENT INVENTION

[0080] FIG. 1a illustrates a cross-sectional portion of a conditioning head 10 though a longitudinal portion of a spiral vane, with the left side positioned proximal to the central axis of the conditioning head and the right side forming the peripheral edge. The conditioning head comprises a backing plate 20, such as a stainless steel plate. The substrate 30 may comprise a variety of materials including ceramic material, such as Si and/or Si.sub.3N.sub.4, or from at least one ceramic material such as Al.sub.2O.sub.3, AlN, TiO.sub.2, ZrO.sub.x, SiO.sub.2, SiC, SiO.sub.xN.sub.y, WN.sub.x, Wo.sub.x, DLC (diamond-like coating), BN and/or Cr.sub.2O.sub.3. In some implementations, the substrate is a carbide.

[0081] The substrate 30 can be made from a cemented carbide material such as tungsten carbides (WC) such as tungsten carbonite-cobalt (WC—Co), tungsten carbonite-carbon titanium-cobalt (WC—TiC—Co) and/or tungsten carbonite-carbon titanium-carbon tantalium-cobalt (WC—TiC—TaC—Co). The substrate 30 can also be made from other cemented carbide materials such as TiCN, B.sub.4C or TiB.sub.2. In some embodiments, the substrate comprises Reaction-Bonded Silicon Carbide (RBSiC) comprising silica carbide and unreacted silica carbide forming material, e.g. Si. Further details on RBSiC are disclosed in U.S. Pat. No. 7,367,875, which is incorporated by reference to the extent it does not conflict with the disclosure herein.

[0082] The substrate is usually in the form of a disk ranging in diameter from about two (2) to four (4) inches (about 50 to 100 mm). However, other geometries have been used as the substrate for conditioning heads. The base substrate thickness ranges from about 0.5 mm to about 6.5 mm and/or about 1.0 mm to about 2.0 mm for a silicon substrate. Thicknesses for other substrates may vary from these ranges. For instance, the silicon carbide-silicon composite substrate may have a thickness ranging from about 1.0 mm to about 7.5 mm, although thicknesses outside this range are also feasible. Larger diameter substrates will be correspondingly thicker.

[0083] The substrate 30 comprises a raised non-planar abrasive region in the form of a spiral vane. The top of the spiral vane 40 is raised approximately between 0.5 mm to 2 mm from the natural plane of the conditioning head.

[0084] Details of the variations in configuration and methods of producing the non-planar abrasive region are further detailed in US20090224370 in the name of the applicant. US20090224370 is incorporated into the current specification to the extent allowable under national law.

[0085] The polycrystalline CVD diamond layer 40 typically covers the whole of the conditioning head, although in some embodiments the vanes may be separately attached to a backing plate. The diamond layer 40 forms the edge shaving region, which covers the majority (e.g. >80%) of the top of the spiral vane and/or the vane side. The edge shaving region of the substrate 40 may be first uniformly distributed with about 100 to 5000 grains per mm.sup.2 of diamond grit, which may have an average particle diameter of less than 10 μm and/or approximately 0.5 to approximately 2 μm. However, seedless formation of the CVD diamond layer is also possible. The concentration and size of the grain as well as the CVD diamond processing conditions, may be adjusted to achieve the desired surface roughness. Further details of the CVD diamond process are provided in paragraphs 73 to 76 of US20090224370, which is incorporated by reference to the extent that it does not conflict with the disclosures herein. Other seeding methods are disclosed in U.S. Pat. No. 6,054,183, which is incorporated by reference to the extent that it does not conflict with the disclosures herein.

[0086] The lateral cross-section view of the vane is the shape of a truncated triangle with the top about 1.1 mm wide. A protrusion 50 (cutting point region) is positioned towards the peripheral edge of the spiral vane at the outer diameter of the conditioning head 10. The protrusion is an enlarged diamond grain adhered to the substrate prior to the CVD diamond layer being applied. The protrusion 50 has a height of 40 μm (R.sub.p2) above the edge shaving region 40 of AB, corresponding to the difference between the peak height of the protrusion to the peak height of the edge shaving region 40. The mean thickness of the protrusion (relative to the substrate) is about 30 μm. In FIG. 1a, the mean CVD diamond layer thickness is about 10 μm for the edge shaving region, with a roughness R.sub.p1 of about 4 μm.

[0087] FIG. 1b illustrates an embodiment in which the point cutting region is defined between enlarged diamond grains 50 and 52. The diamond height AB is 42 μm (R.sub.p2), whilst roughness R.sub.p1 remains at about 4 μm.

[0088] FIGS. 2a to 2f illustrate protrusions positioned towards the peripheral edge of the spiral vanes, such as those illustrated in FIG. 4. The protrusions were formed by adhering single diamond grains (or three diamond grains in FIG. 2e) to the predetermined location prior to applying the CVD diamond layer. Through selection of appropriately sized diamond grains, protrusions may be formed within a height tolerance of ±5 μm. In some implementations, protrusion may be formed with a height tolerance of approximately ±3 μm. FIG. 3a illustrates a substrate with the diamond grain adhered thereto, whilst FIG. 3b illustrates the protrusion formed therefrom after application of the CVD diamond layer. In a variation to the conditioning head of FIG. 4, the spiral vanes form the surface edge shaving region; raised cutting point protrusions may be positioned within approximately 3 mm of the peripheral edge between one or more of the spiral vanes and/or between alternatively spiral vanes. The spiral vanes comprise a shaving edge which is able to efficiently remove the top layers of the polishing pad without an excessive pad wear rate. The small portion of raised cutting points is able to rejuvenate the polishing pad surface by breaking up glazed areas and restoring the asperity structure.

[0089] When compared to the 3M Trizact B5 pad conditioner, the conditioning head of FIG. 4 created about the same contact area (contact area is the area of the polishing pad that will contact the wafer during CMP under 2 psi load). However, the conditioning head of the present invention had a mean contact density (at 2 psi pressure) of 220 counts/mm.sup.2 compared to 129 counts/mm.sup.2 when the polishing pad was conditioned with the 3M pad conditioner. These results indicate that the conditioning heads of the present invention are able to produce a polishing pad asperity structure defined by a higher frequency of smaller asperity peaks. This enables improved wafer material removal and lower wafer defects as the contact areas can stay more lubricated. Larger contact areas can become non-lubricated, causing friction and increased defects.

[0090] FIG. 5 illustrates a portion of a surface profile of a raised spiral vane of FIG. 4. The roughness of the edge shaving region Rp.sub.1 is determined by performing a line scan across the full length of the spiral vane (excluding the cutting point region). In FIG. 4, this involved two separate line scans either side of the protrusion. The largest Rp.sub.1 between the separate line scans was 8 μm, whilst Rp.sub.2 was 41 μm.

[0091] FIGS. 6 to 8 illustrate the shape and dimensions of protrusions formed from the adhering diamond grains to the top surface of the non-planar raised substrate. As illustrated, the protrusions have substantially level top surfaces. FIGS. 9 and 10 illustrate protrusions with rounded tops formed from catalytic seeds, which promoted accelerated diamond growth and resulted in a thicker diamond layer immediately adjacent the catalytic seeds.

[0092] The cross-sectional portion of the grains ranged from about 30 μm to 50 μm. The spiral shaving edge vane has a shaving edge length of about 50 mm. Therefore, the portion of the cutting point/shaving edge functioning as cutting points is about 0.06% to 0.10%. For embodiments in which only half of the vanes comprised these protrusions, the portion of the cutting/shaving edge functioning as cutting points would also be halved.

[0093] FIGS. 11a to 11f provide a number of possible configurations of the raised non-planar edge shaving region. The Rp.sub.1 in all samples was less than 5 μm, whilst the protrusion heights were all greater than 30 μm and less than 50 μm. In embodiments where the region comprises concentric circular vanes (such as those illustrated in FIGS. 11e and 11f), the protrusions of the point cutting region may be disposed on the outermost concentric circular vane. The embodiments shown in FIGS. 11a, 11b, 11c, and 11d each have a series of spiral raised edge shaving regions.

[0094] It will be appreciated that the cutting points may be generated by a variety of means. In one embodiment, the substrate adjacent the cutting point region is distributed with catalytic seeds. Accordingly, the cutting point region may be adjacent catalytic seed(s) disposed upon the substrate. The catalytic seeds may include diamond, silicon, iron, cobalt, nickel and/or alumina. A CVD diamond layer is then deposited, resulting in the cutting point region comprising larger and higher diamond grains relative to the diamond grains forming the edge shaving region.

[0095] In another embodiment, the substrate comprises one or more protrusions which form the cutting point region once coated with CVD diamonds.

[0096] In yet another embodiment, the cutting point region may be obtained through etching protrusions from a diamond layer, as described in U.S. Pat. No. 8,979,6183.

[0097] It is to be understood the implementations are not limited to particular systems or processes described which may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular implementations only, and is not intended to be limiting. As used in this specification, the singular forms “a”, “an” and “the” include plural referents unless the content clearly indicates otherwise. Thus, for example, reference to “a shape” includes a combination of two or more shapes and reference to “a layer” includes different types and/or combinations of layers.

[0098] Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. For the avoidance of doubt, the terms “may”, “and/or”, “e.g.”, “for example” and any similar term as used herein should be interpreted as non-limiting such that any feature so-described need not be present. Indeed, any combination of optional features is expressly envisaged without departing from the scope of the invention, whether or not these are expressly claimed. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim, although not originally claimed in that manner.