Retaining ring with wear pad for use in chemical mechanical planarization
View Patent ↗A novel retaining ring having a wear pad of such construction, design and material such that it provides improved resistance to wear and/or degradation as compared to currently available products for use in the chemical mechanical planarization (CMP) of semiconductor wafers and similar materials. The retaining ring with wear pad of the invention is able to withstand increased operating temperatures and pressures at the polishing surface of the wafer with less wear than would normally be encountered with currently used materials and designs. The ability to operate at increased temperature and pressure can accelerate the rate of removal of material from a semiconductor wafer in some processes. The flexibility of a manufacturer to use an expanded range of temperature and pressure in CMP processes, combined with a significant reduction in the cost of consumables, provides a significant advantage in the final cost of ownership in the production of multilayer, integrated circuit devices and other products where CMP is utilized in manufacture. Moreover, the retaining with wear pad of the present invention may also retrofitted to previously used and worn retaining rings of the prior-art design, thus salvaging the major structural component of the CMP processing apparatus, thereby reducing costs. It is also an integral part of this invention to make the consumable component of the new design replaceable, so as to make replacement of this part less costly when such replacement finally does become necessary.
1. A retaining ring for use with a chemical mechanical planarization (CMP) apparatus for the polishing of wafers, which CMP apparatus comprises a polishing pad for polishing the wafer, the retaining ring holding a wafer for contact against the polishing pad of the CMP apparatus during the polishing process, comprising;
a main body portion, said main body portion having a bottom portion for contacting against a polishing pad during wafer-polishing, and also having an interior annular surface for holding a wafer; and
said bottom portion of said main body portion being made of fibrous material impregnated with a thermosetting resin.
2. The retaining ring according to claim 1 , further comprising an inner absorption means mounted to said main body portion against which a wafer is secured by abutting contact, said inner absorption means absorbing impact from the wafer during the polishing process.
3. The retaining ring according to claim 2 , wherein said bottom portion of said main body portion is stepped and defines an interior annular cutout section; said inner absorption means comprising annular ring means being mounted in said annular cutout section.
4. The retaining ring according to claim 3 , wherein said inner annular absorption ring means has a depth less than the depth of said interior annular cutout section, whereby the bottom surface of said absorption ring means is spaced from, and does not contact, a polishing pad during a wafer-polishing process.
5. The retaining ring according to claim 2 , wherein said inner absorption means is made of thermoplastic material.
6. The retaining ring according to claim 1 , wherein at least said bottom portion of said main body portion comprises hard abrasive particle additive for conditioning a polishing pad as said bottom portion contacts the polishing pad during the polishing process.
7. A method of using a retaining ring for use with a chemical mechanical planarization (CMP) apparatus for the polishing of wafers, which CMP apparatus comprises a polishing pad for polishing the wafer, the retaining ring holding a wafer for contact against the polishing pad of the CMP apparatus during the polishing process, said retaining ring comprising a main portion having a bottom surface and a replaceable bottom wear pad secured to said bottom surface of said main portion for contacting against the polishing pad during the polishing process of the wafer secured in the retaining ring, comprising:
(a) using the bottom wear pad during wafer-polishing in a CMP apparatus by contacting the wear pad against the polishing pad during the polishing process, said step of using contacting only said bottom wear pad against the polishing pad and leaving the main portion of said retaining ring out of contact with the polishing pad during the polishing process; and
(b) replacing the wear pad of step (a) from said bottom surface with another wear pad when the wear-pad of said step (a) has been used up, whereby the main portion of the retaining ring need not be replaced, said step of replacing comprising removably attaching the another wear pad to said bottom surface of said main portion.
8. The retaining ring according to claim 7 , wherein said step (b) comprises inserting insulating layer means between said main portion and said wear pad, whereby heat generated during the wafer-polishing process is retained in order to provide wafer-polishing at elevated temperatures.
9. A retaining ring for use with a chemical mechanical planarization (CMP) apparatus for the polishing of wafers, which CMP apparatus comprises a polishing pad for polishing the wafer, the retaining ring holding a wafer for contact against the polishing pad of the CMP apparatus during the polishing process, comprising;
a main body portion, said main body portion having a bottom portion, and also having an interior annular surface; and
replaceable wear pad means removably secured to said bottom portion of said main body portion for contact against the polishing pad during the polishing process of the wafer secured in the retaining ring, whereby when said wear pad means is used up, it is replaced with another said wear pad means.