Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B37/00—Lapping machines or devices; Accessories
  • B24B37/27—Work carriers
  • B24B37/30—Work carriers for single side lapping of plane surfaces
  • B24B37/32—Retaining rings

Definitions

• CMP Chemical mechanical planarization
• material is removed from a wafer substrate by the action of a polishing pad, a polishing slurry, and optionally chemical reagents. Over time, the polishing pad becomes matted and filled with debris from the CMP process.
• the polishing pad is reconditioned using a pad conditioner that abrades the polishing pad surface and opens pores and creates asperities on the surfaces of the polishing pad. The function of the pad conditioner is to maintain the removal rate in the CMP process.
• CMP represents a major production cost in the manufacture of semiconductor and memory devices. These CMP costs include those associated with polishing pads, polishing slurries, pad conditioning disks and a variety of CMP parts that become worn during the planarizing and polishing operations. When the pad conditioner is worn or a predetermined term of use has been reached the pad is replaced with a new pad. Additional cost for the CMP process includes tool downtime in order to replace the polishing pad and the cost of the test wafers to recalibrate the CMP polishing pad.
• a typical polishing pad comprises closed-cell polyurethane foam approximately
• the pads are subjected to mechanical abrasion in order to physically cut through the cellular layers of the pad surface.
• the exposed surface of the pad contains open cells, which can be used during the CMP process to trap abrasive slurry consisting of the spent polishing slurry and material removed from the wafer.
• the pad conditioner removes the outer layer of cells containing the embedded materials and minimizes removal of layers below the outer layer. Over-texturing of the polishing pad results in a shortened life, while under-texturing results in insufficient material removal rate and lack of wafer uniformity during the CMP step. This technology is described in U.S. published patent application 201401 13532 hereby incorporated by reference in its entirety for all purposes.
• CMP pad conditioner is a four-inch disc with fixed diamond abrasives.
• the diamond coated disc is rotated and pressed onto the polishing pad surface to cut and remove the top layer.
• the diamonds are typically set in an epoxy or a metal matrix material.
• diamonds from these pad conditioners can become dislodged which can lead to yield loss due to scratching of the wafer during the polishing operation.
• the components of the CMP system form an integrated unit such that replacement of any of the components will require a recalibration of the whole system, further increasing the down time of the system.
• the components of the polishing system form a set, such that the best results in preparation of wafers results from components of the system being well matched with each other.
• the invention provides a polishing pad conditioner that has removable and refurbishable and or replaceable conditioning segments.
• the conditioning segments include a ceramic substrate that has a layer of CVD diamond deposited on an outer face that contacts the polishing pad.
• the inner face of the ceramic substrate has threaded recesses present therein by which the segment can be attached and removed from a backing plate. For reuse, the segment is detached from the backing plate and the damaged CVD diamond coating removed. A new CVD diamond coating can then be deposited on the surface of the substrate and the segment reattached to the backing plate.
• the invention also provides for an integrated system for CMP with multiple components with contact surfaces having replaceable segments, the replaceable segments having CVD diamond deposited thereon. The segments being refurbishable by replacing the CVD diamond.
• the conditioning segments are attached to a backing plate that is also reusable to hold new or refurbished conditioning segments.
• a backing plate that is also reusable to hold new or refurbished conditioning segments.
• the invention provides a conditioner for a polishing pad used in a chemical mechanical planarization process comprising a backing plate with a tool mounting side and a segment mounting side and one or more removable segments.
• the removable segments having a front side and a rear side, the rear side fixed to the segment mounting side of the backing plate.
• the front side of the removable segments form a surface that contacts a polishing pad.
• the removable segments are fixed to the backing plate by threaded fastening recesses in the removable segment.
• the removable segment has a substrate formed from a carbide forming material.
• the carbide forming material is tungsten, molybdenum, tantalum, silicon, copper, aluminum, carbon, alumina, silicon carbide, tungsten carbide, titanium carbide, silicon nitride, and boron nitride.
• the backing plate is formed of a carbide forming material, a metal or a ceramic.
• the carbide forming material is the carbide forming material is tungsten, molybdenum, tantalum, silicon, copper, aluminum, carbon, alumina, silicon carbide, tungsten carbide, titanium carbide, silicon nitride, and boron nitride.
• the metal is stainless steel, molybdenum, or aluminum and the ceramic is alumina, steatite or zirconia.
• the invention provides a refurbishable segment for a CMP polishing pad conditioner comprising a removable segment designed and configured to be removably fixed to a backing plate.
• the backing plate having a plurality of apertures or through holes therein designed to mate with threaded recesses in the removable segment.
• the removable segment includes a substrate of a carbide ceramic and the threaded recesses are machined into a graphite prepreg of the segment prior to ceramization of the segment.
• the side of the removable segment contacting the CMP polishing pad has a layer of CVD diamond grown thereon.
• the refurbished segment can then be re-fixed to the backing plate.
• the invention provides a method of making a conditioner for a polishing pad used in a chemical mechanical planarization process including providing a prepreg for a removable conditioning segment machined from a graphite block. Providing threaded recesses in the prepreg dimensioned and configured to mate with features on a backing plate. Ceramisizing the prepreg by converting the graphite prepreg into a carbide ceramic segment and installing screw thread coils, such as a heli-coil®, in one or more of the threaded recesses created in the carbide ceramic; and fixing one or more ceramic segments to a backing plate using threaded fasteners.
• the method further includes growing a layer of CVD diamond on the surface of the segments.
• the carbide ceramic is formed from tungsten, molybdenum, tantalum, silicon, copper, aluminum, carbon, alumina, silicon carbide, tungsten carbide, titanium carbide, silicon nitride, and boron nitride.
• the backing plate is fashioned from metal or ceramic.
• the metal is stainless steel, molybdenum, or aluminum and the ceramic is alumina, steatite or zirconia.
• the invention provides for An integrated system for use in chemical mechanical planarization comprising: replaceable contact segments used in the CMP process wherein the contact segments comprise a carbide substrate having threaded recesses allowing the contact segments to be fastened to a backing support using a threaded fastener; wherein replacing the contact segments does not require replacing the backing support.
• the replaceable contact segment further includes a layer of CVD diamond deposited on the contact surface.
• the replaceable contact segments include CMP polishing pad conditioner contact segments and retaining ring contact segments.
• the carbide substrate is machined from a graphite precursor.
• the CVD diamond coating of the contact segments is optimized for use with other components of the system and does not exclude a different CVD diamond variant for the different components of the CMP system.
• the carbide substrate is formed from a carbide forming material including tungsten, molybdenum, tantalum, silicon, copper, aluminum, carbon, alumina, silicon carbide, tungsten carbide, titanium carbide, silicon nitride, and boron nitride.
• FIGs. 1 A-C illustrate several embodiments of polishing pad conditioners.
• FIG. 2A is a top plan, perspective view of a polishing pad conditioner backing plate having three of five replaceable conditioning segments attached. Also shown are the fastener through holes in the backing plate. The inset, FIG. 2B illustrates a fourth conditioning segment from a rear perspective view ready for attachment to the backing plate.
• FIGs. 3A-C include a perspective, top plan view of the backing plate shown in FIG. 2, a perspective bottom plan view of a conditioning segments in FIG. 3B and a top plan view of the same segment in FIG. 3C.
• FIG. 4 is a top plan view of a separate backing plate embodiment.
• FIGs. 5A-C are various views of conditioning segments according to various embodiments of the invention.
• 5A is a schematic top plan view of a conditioning segment optimized at the edges.
• FIG. 5B is a bottom plan view of a segment having a variety of attachment and fixation pockets.
• FIG 5C is a photomicrograph of a conditioning segment with etched topography.
• FIGs. 6A and 6B illustrate the attachment of the removable conditioning segment to the backing plate and the backing plate to the conditioning head.
• FIG. 6A is an exploded view of the attached segment shown in FIG. 6B
• compositions and methods are described in terms of “comprising” various components or steps (interpreted as meaning “including, but not limited to”), the compositions and methods can also “consist essentially of or “consist of the various components and steps, such terminology should be interpreted as defining essentially closed or closed member groups.
• the terms “ceramization” and “ceramisizing” refer to the process of making a ceramic from a ceramic precursor.
• diamond has a significantly lower coefficient of friction than the materials used in the CMP process today, and is among the lowest coefficient of friction (COF) materials available. This low COF will greatly reduce the shear and horizontal frictional forces on the pad reducing or eliminating the pad push under the wafer edge.
• the diamond coating or in some versions a polycrystalline diamond coating can be further coated with diamond like carbon to provide some charge dissipation and modified coefficient of friction.
• the diamond coating on the segments also has excellent heat transfer characteristics and will remove heat from the process allowing greater design control over the application.
• Diamond is also the hardest material available, this will enable a long process life for segments utilized on the ring.
• the diamond film will be available to be measured by the CMP tools end point detection system employed for the wafer. By also picking up the diamond layer, the film thickness can be observed and the ring end of life can be determined by the remaining film thickness.
• Converting a near net shaped porous graphite precursor to a near net shaped silicon carbide pad conditioner can provide cost advantages over texturing silicon carbide directly, because machining silicon carbide is a difficult and time-consuming process due to its hardness.
• the pad conditioner surface or segment is then adhered to the conditioning base plate by adhesive, such as epoxy.
• U.S. Patent 8,142,845 to Rashed et al. (incorporated by reference herein in its entirety) describes machining a graphite block into a near-net shape article and then contacted with silicon monoxide gas at a first preselected temperature to form the porous silicon carbide preform.
• the first preselected temperature is in a range of about 1400° C to about 2000° C.
• a substantial number of pores within the porous silicon carbide preform are then filled with a carbon precursor to produce a filled silicon carbide preform.
• the carbon precursor is a gas
• the filled carbide preform has its pores at least partially filled with the gas.
• the carbon precursor impregnates or infiltrates the porous silicon carbide preform to produce a carbon structure within the open pores of the porous silicon carbide preform.
• the carbon precursor is liquid
• the filled silicon carbide preform is then heated at a second preselected temperature to polymerize the carbon precursor contained within the filled silicon carbide preform to form a polymerized filled silicon carbide preform.
• the second preselected temperature is in a range of about 70° C. to about 250° C.
• Another preferred embodiment includes the second preselected temperature being in a range of about 90° C. to about 150° C.
• the polymerized filled silicon carbide structure is further heated at a third preselected temperature to produce a carbonaceous porous structure within the pores of the porous silicon carbide preform.
• the carbonaceous porous structure is essentially charred.
• the third preselected temperature is in a range of about 800° C to about 1800° C. In a preferred embodiment, the third preselected temperature is in a range of about 800° C. to about 1200° C. The process can be repeated until the desired amount of carbon is produced within the pores of the porous SiC preform.
• the carbonaceous porous structure is then contacted with silicon in an inert atmosphere at a fourth preselected temperature and a first preselected pressure.
• the fourth preselected temperature is about above a melting point of silicon.
• the silicon infiltrates or diffuses through the carbonaceous porous structure and reacts with carbon contained within the pores of the porous silicon carbide preform to produce silicon carbide within the pores of the porous silicon carbide preform.
• the produced silicon carbide is a near-net shape dense silicon carbide article.
• the conversion of carbon to SiC is accompanied with an increase in the molar volume which results in densification.
• the produced dense silicon carbide has essentially no or substantially reduced open porosity.
• the current inventors have recognized that, in its graphite, prepreg, stage, SiC segments provide a unique opportunity to introduce features into the SiC component substrate which not only makes the component more usable, but also makes the components reusable providing the only CMP components which are not encumbered with the built-in obsolescence of conventional CMP components.
• the graphite prepregs can be machined to include screw or fixture holes in the rear (non-contact) face, of the segment. Therefore, in use, the SiC segment does not have to rely on adhesive to adhere it to a backing ring, can be removed from a backing plate as desired and can be reattached following a refurbishing process.
• CVD diamond could be grown on the finished SiC segment substrates as is known in the art. Because of its hardness, inertness and high melting point, 2,730° C SiC provides the ideal substrate on which to grow CVD diamond.
• a carbon gas is ionized at very high temperatures using microwave power, hot filament a laser or electron beam or the like and the ionized carbon deposits on the substrate as diamond. During this process the substrate can reach temperatures of about 800° C. Because the melting point of PEEK and PPS is much lower 343° C and 218° C respectively, conventional materials for making CMD components are simply not applicable for the growth of CVD diamond.
• the segments can be securely attached to a backing plate by the threaded holes and readily detached allowing the ability to not just to replace segments on the backing ring but to refurbish used segments by removing the diamond layer and re-depositing a new CVD - diamond layer on the existing SiC segment substrate.
• FIGs. 1A, B and C illustrate several exemplary embodiments of polishing pad conditioners 10 according to the invention.
• removable conditioning segments 12a, 12b and 12c can be fabricated as described above, the ceramisized segments are then attached to a backing plate 14 by means of a screw or bolt through the backing plate 14 and into the threaded holes (not shown) in the back of the conditioning segment 12.
• FIG. 2 illustrates the assembly of conditioner 10 according to one exemplary embodiment of the invention.
• FIG. 2A is a perspective top plan view of a conditioner backing plate.
• 44a are thread support for fasteners 50 mounting the backing plate 14 to the conditioning tool head 54 (not shown).
• 42a are thread supports for mounting the removable segment 12a to the backing plate 14.
• FIG. 2B is a perspective view of the underside of a conditioning segment 12a flipped alone line a-a.
• Pocket 44b is clearance for thread support 44a of backing plate 14 which are used to secure the retaining ring to the conditioning head.
• Recesses 42b are threaded holes for fasteners such as screw or bolts (not shown) which pass through fastening holes 42a of backing plate 14 and secure the conditioning segments to backing plate 14.
• FIG. 3 is a perspective, rear plan view of a backing plate 14 according to the embodiment illustrated in FIG. 2. Fastening holes 42a and 44a are illustrated. In some embodiments, the holes are the same size from a rear view.
• FIG. 4 is a schematic rear, perspective view of a universal backing plate 14 according to one embodiment of the invention. As seen in this embodiment, a single backing plate can be made to accommodate various conditioner segment profiles.
• FIG. 5A is a schematic top plan view of one embodiment of a conditioner segment 12 according to the invention.
• FIG. 5B is a perspective bottom plan view of the conditioner segment shown in FIG. 5A showing a universal set of fastening recesses complementary to those of universal backing plat shown in FIG. 4. Note in this embodiment, not all fastener recesses need to be unutilized to secure the segment 12 to backing plate 14.
• FIG. 5C is a photomicrograph of a conditioning segment according to one embodiment of the invention having CVD diamond grown on the surface.
• FIGs 6A and 6B illustrate the attachment of the removable segment 12 to the backing plate 14 and to the conditioning head 54.
• FIG. 6 A is an exploded view showing fastener 50a connecting conditioner head 54 to backing plate 14. Also shown are fasteners 50b connecting backing plate 14 to conditioner segment 12. Screw thread coils 52 can be inserted in the ceramic with the threaded insert machined into the graphite prepreg.
• polishing pad conditioner provides many benefits over conventional conditioners.
• SiC is extremely hard providing the substrate with useful longevity.
• diamond has a very high thermal conductivity and can there for act as a heat sink further increasing the efficiency and longevity of the CMP system and components.
• Fifth, diamond has an extremely low coefficient of friction to greatly reduce shear and horizontal frictional forces on the polishing pad.
• the diamond coating, the SiC conditioning segments and a backing plate made of resistant substrates such as carbides or metals such as stainless steel, molybdenum, or aluminum are much more inert to the chemistry of the CMP process than are polymers such as PEEK or PPS. Further, all of these factors act to lower the wear rate not only of the polishing pad conditioner but of the CMP system.
• the methods and components of the invention allow a customized solution to various problems of the silicon wafer manufacturing process.
• the method and components described herein allows the user to match morphology and composition of the components, including the polishing pad, wafer retaining ring and polishing pad conditioner to CMD process specifics, such as the pressure a wafer is subjected to on the polishing pad, types of chemicals used to polish the wafer, slurry types and/or the processes used to condition the polishing pad.
• CMD process specifics such as the pressure a wafer is subjected to on the polishing pad, types of chemicals used to polish the wafer, slurry types and/or the processes used to condition the polishing pad.
• Those of skill in the art recognize that all the components of the CMD process are integrated such that more durable construction of the components and longer use in the system results in less down time and faster return to operation upon reconditioning of the segment.
• the invention disclosed herein provides for removable and refurbishable conditioning segments for use in the CMP process.
• a similar technology has been developed
• the invention described herein allows the user to reduce development time and cost because removable segments both for a conditioning and for a retaining ring can be removed from a backing plate or backing ring and the CVD diamond can be stripped from the SiC segment using high temperatures in an oxidizing atmosphere.
• the SiC substrate segments can be re-coated to offer many variants of CVD film to allow for ideal alignment with process requirements. This includes providing a diamond surface for a conditioning segment which is optimized for cleaning a polishing pad and providing a diamond surface for a retaining ring that is optimized for low friction and to eliminate or decreases pad push at the wafer edge.
• the CVD diamond film's chemical and or physical properties and or morphology can be modified to align with CMP process demands, for example retaining ring pressure or slurry or polishing chemistry. Additionally the morphology and composition of the CVD diamond film can be modulated to align with process requirements. For example, the roughness of the diamond film can be varied through CVD process conditions. Further, diamond coating deposited by the CVD process is more stably adhered to the substrate then when attached via epoxy or other adhesive.
• the carbide forming segment substrate can be re-coated to offer many variants of
• CVD film to allow for ideal alignment with process requirements.
• the used or worn diamond coating can be removed by a plasma etching process until the underlying silicon carbide is exposed and then recoated with CVD diamond.
• the CVD diamond coating on the carbide forming segments can be made using hot filament chemical vapor deposition as disclosed in WO/1 99/002309 to Zimmer et al incorporated herein by reference in its entirety.
• Materials for ceramic segments that comprise the retaining ring in versions of the present invention, methods of making and shaping the ceramic segments, and materials and methods for coating them with CVD diamond are disclosed in WO/2012/122186, Galpin et al, the contents of which are incorporated herein by reference in its entirety.
• the CVD diamond deposited on the ceramic segment is polycrystalline diamond.
• a diamond like carbon (DLC) coating can be applied over the CVD diamond on the one or more segments.
• Diamond like carbon coatings can advantageously be used to modify the coefficient of friction, the wear rate, and the electrical charge dissipation of the retaining ring.
• the backing plate can be formed of a rigid material such as a metal, e.g., stainless steel, molybdenum, or aluminum, or a ceramic, e.g., alumina, steatite or zirconia, or other exemplary materials.
• a metal e.g., stainless steel, molybdenum, or aluminum
• a ceramic e.g., alumina, steatite or zirconia, or other exemplary materials.
• the backing plate can also be made from the same carbide forming materials as the conditioning segments such as are tungsten, molybdenum, tantalum, silicon, copper, aluminum, carbon, alumina, silicon carbide, tungsten carbide, titanium carbide, silicon nitride, and boron nitride.
• the backing plate can include structures like bolts, holes, threaded structures and the like for attaching segments to a surface of the backing plate and for securing the backing plate to the carrier head of a polishing pad conditioning
• the backing plate or a backing ring for use with a retaining ring may include one or more additional layers, for example as disclosed in U.S. Pat. No. 6,251,215, Zuniga et al, the contents of which are incorporated herein by reference in its entirety.
• the removable segments may be substituted for the lower portion 180 and bonded to upper portion 184 as illustrated in U.S. Pat. No. 6,251,215.
• the segments that are fixed to the backing plate can be made from carbide-forming materials to create a surface that is more favorable for diamond growth.
• the segments can be carbide forming materials including metals, such as tungsten, molybdenum, tantalum, silicon, copper, aluminum, or non-metals, such as carbon, alumina, silicon carbide, tungsten carbide, titanium carbide, silicon nitride, and boron nitride.
• the segments can be a ceramic material.
• the segments comprise silicon carbide.
• the silicon carbide can be formed from graphite precursors and may be porous or may be porous silicon carbide whose porosity is closed.
• the silicon carbide may also be a dense silicon carbide.
• Segments can be fixed or secured to the backing plate by various techniques or a combination of techniques. For example, one or more screws or bolts may be inserted through the backing ring and into one or more threaded holes or threaded inserts in a segment.
• versions of the invention can include segments that are a combination of two or more smaller segments.
• a carbide forming material can have two, three, or more individual conditioning. These larger segments can then be fixed to the backing plate.
• a conditioner for a polishing pad used in a chemical mechanical planarization process comprising:
• a backing plate with a tool mounting side and a segment mounting side; one or more removable segments, the removable segments having a front side and a rear side, the rear side fixed to the segment mounting side of the backing plate, the front side of the removable segments form a surface that contacts a polishing pad;
• a refurbishable segment for a CMP polishing pad conditioner comprising: a removable segment designed and configured to be removably fixed to a backing plate;
• a backing plate having a plurality of apertures therein designed to mate with threaded recesses in the removable segment
• the removable segment includes a substrate of a carbide ceramic and the threaded recesses are machined into a graphite prepreg of the segment prior to ceramization of the segment.
• a method of refurbishing a CMP polishing pad conditioner comprising: removing CVD diamond from one of more surfaces of a worn diamond coated segment to provide and uncoated segment;
• a method of making a conditioner for a polishing pad used in a chemical mechanical planarization process comprising:
• fixing the segments to the backing plate comprises using a screw, bolt, adhesive or combinations thereof, to fix the segments to holes in the backing plate.
• the carbide ceramic is formed from tungsten, molybdenum, tantalum, silicon, copper, aluminum, carbon, alumina, silicon carbide, tungsten carbide, titanium carbide, silicon nitride, and boron nitride.
• An integrated system for use in chemical mechanical planarization comprising:
• replaceable contact segments used in the CMP process wherein the contact segments comprise a carbide substrate having threaded recesses allowing the contact segments to be fastened to a backing support using a threaded fastener; wherein replacing the contact segments does not require replacing the backing support.
• replaceable contact segment further includes a layer of CVD diamond deposited on the contact surface.
• replaceable contact segments include CMP polishing pad conditioner contact segments and retaining ring contact segments.

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• Grinding-Machine Dressing And Accessory Apparatuses (AREA)

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• 2014
  • 2014-07-11 WO PCT/US2014/046430 patent/WO2015006745A1/en active Application Filing
  • 2014-07-11 WO PCT/US2014/046427 patent/WO2015006742A1/en active Application Filing
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