Patent Grant
9272390
This application claims the priority of Taiwanese patent application No. 102128884, filed on Aug. 12, 2013, which is incorporated herewith by reference.
1. Field of the Invention
The present invention relates generally to a pad conditioning tool for Chemical Mechanical Polishing (CMP) process, and more particularly a pad conditioning tool that has a plurality of sapphire dressing particles for dressing a wafer polishing pad such that the wafer polishing pad possesses high efficient polishing yield.
2. The Prior Arts
Rapid advance of semiconductor product and optical instrument demands minimizing width of circuit paths in the integrated circuit board. The more the circuits are integrated into a chip, the more planarization of surfaces in the semiconductor material is required, since formation of a circuit or thin film is obtained only after each deposition process. To be more specific, if the integrated circuit includes 10 conductive layers (like Cu, Al, W), insulated layers (like black diamond) and anti-abrasive layer, several deposition processes are conducted so as to form the 10 conductive layers. Since smoothing of the surface is required after formation of each layer, presently Chemical Mechanical Polishing (CMP) technique is generally applied in the production of a semiconductor, which in fact is a process of smoothing surfaces of silicone wafers or other base material with the combination of chemical and mechanical forces, so that it is named CMP. The CMP technique generally includes two parts, namely, (I) polishing the semiconductor surface with a polishing pad; and (II) conditioning the polishing pad to provide effective polishing ability.
The conventional pad conditioning tool generally includes a plurality of diamond particles formed on a metal substrate via hard brazing process. Because the diamond particles protrude outwardly from the outer surface at different heights, the exterior appearance and dimension or height is not uniform so that the diamond conditioning tool can only provide roughly about 40% polishing effect. Note that thousands of diamond particles are electroplated or via hard brazing process onto the metal substrate so that there exists co-relation between the surface areas and the number of diamond particles mounted within the surface area and the diamond particles at the adjoining surfaces may fall off owing to contraction and expansion of the metal substrate at different temperatures. The diamond particles may fall off upon introduction of the slurry and the etching process on the metal substrate or the tips of the diamond particles break off owing to non-uniform strength, which, in turn, may result in scratches partially or wholly on the wafer being polished. Of late, a pad conditioning tool has been developed, which includes an integrally formed polishing pad made from relatively hard sapphire material and which are exposed to an exterior more evenly and thus provides longer service life and efficient polishing rate. However, the polishing surface of the polishing pad conditioned by the above-mentioned pad conditioning tool still suffers a new cilia and trench error of 10˜20 μm, which needs to be overcome.
Therefore, how to develop a pad conditioning tool, which does not suffer the disadvantages, like the diamond particles falling off the metal substrate owing to expansion and contraction of the metal substrate at different temperatures, etching of the adhesion layer in coming contact with the polishing slurry, resulting of scratches on the surface of the article being polished, the tool serving a longer service life and providing high yield of the finished products.
A primary objective of the present invention is to provide a pad conditioning tool which is capable of wiping the undesired abrasive waste and micro particles entirely and clearly from the polishing pad and simultaneously forming new trenches and cilia structure in the polishing surface. The pad conditioning tool of the present invention includes a sapphire substrate with a specific orientation plane, wherein the specific orientation plane is selected from a group consisting of a-plane, c-plane, r-plane, m-plane, n-plane and v-plane, the sapphire substrate further defining a mounting surface; and a plurality of sapphire dressing particles and a plurality of scrapers formed on the mounting surface of the substrate in a predetermined geometric arrangement, wherein the dressing particles are scattered between an adjacent pair of the scrapers. In case a wafer polishing pad is conditioned by the dressing particles of the pad conditioning tool, the scrapers are capable of removing abrasive waste and particles entirely and clearly from the wafer polishing pad during a dressing operation, thereby forming new trenches and cilia structure on a polishing surface of the wafer polishing pad.
In one embodiment, the sapphire substrate has a center axis or an eccentric axis and an outer periphery. Each of the scrapers extends radially or inwardly from the outer periphery and terminating adjacent to the center axis or the eccentric axis.
Preferably, each of the scrapers is elongated and extends in a straight line to terminate adjacent to the center axis or eccentric axis.
Alternately, each of the scrapers is curved and extends in a curved line to terminate adjacent to the center axis or eccentric axis.
Each of the dressing particles is shaped like a symmetric truncated cone with a flat head.
Each of the dressing particles and each of the scrapers respectively have a height difference therebetween. Preferably, the height difference between the dressing particle and the scraper ranges 3˜15 μm.
Alternately, the height difference between the dressing particle and the scraper ranges 3˜50 μm.
Each of the dressing particles and each of the scrapers are respectively shaped like an asymmetric truncated cone with a flat head.
Preferably, the flat head of each of the dressing particles and the flat head of each of the scrapers have different widths measured in a transverse direction of their respective top and the widths are different from each other by less than 50 μm.
In one embodiment of the present invention, the sapphire substrate defines two opposite mounting surfaces. The sapphire dressing particles and the scrapers are formed on the mounting surfaces of the sapphire substrate in the predetermined geometric arrangement.
Owing to the specific geometric arrangement between the dressing particles and the scrapers, the undesired abrasive waste and micro particles from the wafer polishing pad are wiped off entirely and clearly during the dressing operation, thereby forming new trenches and cilia structure on a polishing surface of the wafer polishing pad.
The present invention will be apparent to those skilled in the art by reading the following detailed description of a preferred embodiment thereof, with reference to the attached drawings, in which:
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
In this embodiment, the dressing particles 41 and the scrapers 42 do not overlap relative to each other. According to the present invention, the sapphire substrate 40 has a center axis and an outer periphery. Each of the scrapers 42 extends radially and inwardly from the outer periphery and terminating adjacent to the center axis. Each of the scrapers 42 is preferably elongated and thus extends in a straight line. When a wafer polishing pad 3 is conditioned by the dressing particles 41 of the pad conditioning tool 4 of the present invention, the scrapers 42 are capable of removing the undesired abrasive waste and micro particles entirely and clearly from the wafer polishing pad 3 during the dressing operation, thereby forming new trenches and cilia structure on a polishing surface of the wafer polishing pad 3.
The growth techniques of the sapphire substrate 40 to possess the specific orientation direction, includes ingot coring, tail cutting, end plane grinding, cylindrical grinding, multi-wire saw cutting, single or double side lapping and polishing to form the sapphire substrate. Later, coating a photo resistance layer, photolithography process, wet or dry etching, hard baking, deposition process are conducted and these actions are not directly related to the pad conditioning tool of the present invention and thus is omitted herein for the sake of brevity.
It is to note that the height H1 of each dressing particle 41 should be greater than the height H2 of each scraper 42, since the tips of the dressing particles 41 must be exposed to an exterior of the scrapers 42, only then the conditioning of a wafer polishing pad can be carried out so as to permit formation of new trenches and cilia structure in the wafer polishing pad. The scrapers 42 is required to remove the undesired abrasive waste and micro particles from the wafer polishing pad 3 when the same is being conditioned by the pad conditioning tool 4 of the present invention. The pad conditioning tool 4 of the present invention provides high efficient performance if each dressing particle 41 and the scraper 42 is shaped like a symmetric truncated cone with a flat head, as best shown in
Referring to
In order to achieve the height difference between the dressing particle 41 and the scraper 42, twice coating and deposition processes are required to form two photo resistance layers. Each process includes coating photo resistance material, lithographic exposure, hard baking and wet or dry etching operations and etc to form the dressing particle 41 and the scraper 42, where both posses the same height while another process results the height difference between the dressing particle 41 and the scraper 42. Any other fabrication means can be performed so long as they provide the targeted features.
Referring to
It is to note that owing to the above-mentioned eccentric arrangement of the scrapers 42 on the sapphire substrate 40, the undesired abrasive waste and the micro particles are wiped off entirely and clearly from the polishing pad when the former is being conditioned by the pad conditioning tool 4 of the present invention without leaving dead angles. In addition, the layout design or track of the pad conditioning tool of the present is simplified when compared to the prior art ones.
Although the present invention has been described with reference to the preferred embodiments thereof, it is apparent to those skilled in the art that a variety of modifications and changes may be made without departing from the scope of the present invention which is intended to be defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102128884 A | Aug 2013 | TW | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 8398466 | Sung et al. | Mar 2013 | B2 |
| 20090098807 | Bakshi et al. | Apr 2009 | A1 |
| 20100248596 | Sung | Sep 2010 | A1 |
| 20110275288 | Sung | Nov 2011 | A1 |
| 20120302146 | Sung | Nov 2012 | A1 |
| 20150004787 | Hung et al. | Jan 2015 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20150044950 A1 | Feb 2015 | US |
