News Column

"Composite Conditioner and Associated Methods" in Patent Application Approval Process

May 22, 2014



By a News Reporter-Staff News Editor at Politics & Government Week -- A patent application by the inventor Sung, Chien-Min (Tansui, TW), filed on March 12, 2013, was made available online on May 8, 2014, according to news reporting originating from Washington, D.C., by VerticalNews correspondents.

This patent application has not been assigned to a company or institution.

The following quote was obtained by the news editors from the background information supplied by the inventors: "For the tiny copper circuit or the interlayer tungsten circuit on the silicon wafer surface, even for the oxide film dielectric layer of the insulated circuit, making the surface flat through the planarization process to facilitate the subsequent process steps is necessary. Currently, with the process of manufacture integrated circuits (IC) on the semiconductor wafer, the most outstanding planarization technology is the chemical-mechanical planarization (CMP), which flattens a surface by pressing the wafer grinding on a rotating polishing pad.

"The chemical-mechanical planarization is processed by transferring the slurry in between the wafer and the polishing pad stably and evenly to soak the polishing pad surface with slurry which containing chemicals (for instance, acid and oxidant) to erode the film on the wafer surface. The myriad of nano ceramics abrasive (ex. SiO2, Al2O3 and CeO2) in the slurry further pierce and scrape trace film, and simultaneously conduct chemical etching and mechanical grinding to remove the protruding deposit layer on the wafer. The purpose of planarization can be achieved by polishing the wafer surface.

"A conditioner, whose function is to polish pad, is a necessary supply for chemical-mechanical planarization. The so-called condition is directed to shaving polishing pad surface and removing the waste accumulated on the polishing pad surface to maintain the roughness of the polishing pad surface. In addition, a conditioner could also produce tiny uplift and compression on the surface, and it is known as the height different of the asperities. Accordingly, the contact area on the polishing pad would be reduced significantly. Once the contact area becomes smaller, the contact pressure becomes greater to make the slurry at the contact point extrusion the protruding part of the wafer and the chemicals (ex. H2O2) in the slurry would be oxidation to soften or erode the wafer.

"However, the waste produced in the process of the chemical-mechanical planarization, including the debris of the wafer, ex. copper wires, tungsten filled holes, oxidation film, slurry, abrasive and polishing pad scrap etc, the debris usually accumulates on the polishing pad surface and is pressed to become glaze. Once the glaze is formed, polishing pad would become slippery and difficult to maintain grinding power. Therefore, after polishing each wafer, it is necessary to utilize a conditioner to achieve the grinding efficiency of the process (ex. polishing speed) and flatness (ex. the thickness distributed of the wafer coating) as to stabilize the wafer quality.

"However, previous diamond conditioner is usually secured the diamond on the metal table surface by binder. Although it is adapted for conditioning the polishing pad, with regard to the more accurate chemical-mechanical planarization process, scratch, partial dishing, erosion and thickness non-uniformity of the wafer would cause easily by the rough asperities of the polishing pad. The smaller the required IC critical dimension, the greater the demand to the flatness of the wafer surface, also the greater the demand to the conditioner, and which can lead to previous diamond conditioner not being able to satisfy the pre-requirement of the chemical-mechanical planarization process smaller than 45 nm.

"In an effort to obtain a dresser with abrasive tips that are as level as possible, it is often prudent to use diamond abrasives of high shape regularity, and the crystal surface coverage of this kind of crystal is quite high, otherwise, using the crystal with low crystal surface coverage would cause an overshooting height difference. Additionally, a diamond having the highest polishing pad penetration ability, the so-called killer diamond, presents no difference when compared to other diamonds with respect to pad height. In order to meet the demand for a smaller critical dimension, continuing improvement of the conditioner is necessary. Using the sharper polishing tips and maintaining the flatness of the tips height (i.e. the difference of the polishing tips top height), making conditioner forming the subtler and more uniform nick on the polishing pad, and improving the removal ratio to the polishing pad simultaneously, by this, it is efficient to remove the hard layer and recover the asperities on the polishing pad to polish the coating on the wafer rapidly."

In addition to the background information obtained for this patent application, VerticalNews journalists also obtained the inventor's summary information for this patent application: "The present disclosure provides efficient methods, devices, and systems of conditioning a CMP pad. In one aspect, for example, a composite conditioner can include a base plate and a plurality of polishing units secured to a surface of the base plate by an adhesive layer, where each polishing unit includes a plurality of polishing tips secured in a binding layer. Additionally, a height difference between a first highest polishing tip and a second highest polishing tip is less than or equal to about 10 .mu.m, a height difference between the first highest polishing tip and a tenth highest polishing tip is less than or equal to about 20 .mu.m, and a height difference between the first highest polishing tip and a 100th highest polishing tip is less than or equal to about 40 .mu.m. Furthermore, the first highest polishing tip protrudes from the binding layer to a height of greater than or equal to about 50 .mu.m. In some aspects, at least 1% of the plurality of polishing tips actively condition a CMP pad during a conditioning process. In other aspects, less than 40% of the surface of the base plate is covered with polishing units. The polishing units can be arranged on the plate in a variety of configurations. Non-limiting examples can include a single ring, double rings, multi-rings, radial arrangements, spiral arrangements, and the like.

"In another aspect of the present disclosure, a method of making a composite conditioner can include disposing a second mold on a first mold, wherein the second mold includes a plurality of holes, placing a polishing unit in each of the plurality of holes of the second mold, where each polishing unit includes a plurality of polishing tips secured in a binding layer, applying an adhesive layer over the second mold to secure the polishing units, and removing the first mold and the second mold to form a composite conditioner. Regarding the conditioner, a height difference between a first highest polishing tip and a second highest polishing tip is less than or equal to about 10 .mu.m, a height difference between the first highest polishing tip and a tenth highest polishing tip is less than or equal to about 20 .mu.m, and a height difference between the first highest polishing tip and a 100th highest polishing tip is less than or equal to about 40 .mu.m and the first highest polishing tip protrudes from the binding layer to a height of greater than or equal to about 50 .mu.m.

"In yet another aspect, a process of chemical-mechanical planarization (CMP) can include polishing a wafer against a rotating polishing pad and applying the conditioner as has been described against the polishing pad to remove debris and condition the pad.

"There has thus been outlined, rather broadly, various features of the invention so that the detailed description thereof that follows may be better understood, and so that the present contribution to the art may be better appreciated. Other features of the present invention will become clearer from the following detailed description of the invention, taken with the accompanying claims, or may be learned by the practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1A to 1G show a flow chart of manufacturing a composite conditioner in accordance with one embodiment of the present invention;

"FIG. 2A to 2G show a flow chart of manufacturing the composite conditioner in accordance with one embodiment of the present invention;

"FIG. 2H shows a top view of a composite CMP pad dresser in accordance with an embodiment of the present invention;

"FIG. 3 shows a comparison chart of the tip height difference and the working granule amount of a conditioner in accordance with one embodiment of the present invention as compared to a prior art conditioner;

"FIG. 4 shows a comparison chart of the height difference (.mu.m) and the scratch amount of the first highest point and the second highest point of a conditioner in accordance with one embodiment of the present invention as compared to a prior art conditioner;

"FIG. 5 shows a comparison chart of the scratch amount and the removal rate of a conditioner in accordance with one embodiment of the present invention as compared to a prior art conditioner;

"FIG. 6 shows a comparison chart of the in use time and the removing rate of a conditioner in accordance with one embodiment of the present invention as compared to a prior art conditioner;

"FIG. 7 shows a comparison chart of the polishing wafer amount and the removal rate of a conditioner in accordance with one embodiment of the present invention as compared to a prior art conditioner;

"FIG. 8 shows a schematic diagram of the chemical-mechanical planarization process in accordance with one embodiment of the present invention; and

"FIG. 9 shows a schematic diagram of polishing granules in accordance with one embodiment of the present invention.

"It will be understood that the above figures are merely for illustrative purposes in furthering an understanding of the invention. Further, the figures are not drawn to scale, thus dimensions, particle sizes, and other aspects may, and generally are, exaggerated to make illustrations thereof clearer. Therefore, departure can be made from the specific dimensions and aspects shown in the figures in order to produce the heat spreaders of the present invention."

URL and more information on this patent application, see: Sung, Chien-Min. Composite Conditioner and Associated Methods. Filed March 12, 2013 and posted May 8, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=2636&p=53&f=G&l=50&d=PG01&S1=20140501.PD.&OS=PD/20140501&RS=PD/20140501

Keywords for this news article include: Patents, Chemicals, Chemistry.

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Source: Politics & Government Week


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