Claims
- 1. A polishing pad for use with a polishing fluid comprising:a polishing layer and a window in an opening through the polishing layer, the undersurfaces of which are covered by an underlying fluid impermeable layer; an adhesive on the fluid impermeable layer forming respective bond seals with the polishing layer and the window to resist wetting of an interface between the adhesive and each of, the polishing layer and the window and the fluid impermeable layer; the fluid impermeable layer spanning the polishing layer; the fluid impermeable layer being optically transmissive and spanning across the window and the opening; and the fluid impermeable layer being a continuous barrier to leakage of polishing fluid.
- 2. The polishing pad of claim 1 wherein, the fluid impermeable layer comprises, a flexible thin film of hydrophobic polymeric material.
- 3. The polishing pad of claim 1 wherein, the adhesive is of minimized thickness to maximize its optical transparency.
- 4. The polishing pad of claim 1 wherein, the adhesive is a pressure sensitive adhesive that is hydrophobic.
- 5. The polishing pad of claim 1, and further comprising, a backing layer adhered to the fluid impermeable layer, with the fluid impermeable layer being between the backing layer and the polishing layer, and an opening through the backing layer, the opening through the backing layer being aligned with the window in the opening through the polishing layer.
- 6. The polishing pad of claim 5 wherein, the backing layer around a periphery of the opening through the backing layer forms a circumferential ledge that serves as a seat for the window and the fluid impermeable layer.
- 7. The polishing pad of claim 5 wherein, the opening through the backing layer is smaller in circumference than the opening through the polishing layer.
- 8. The polishing pad of claim 5 wherein, additional adhesive adheres the backing layer to the fluid impermeable layer.
- 9. The polishing pad of claim 8 wherein, the additional adhesive is of minimized thickness to maximize its optical transparency.
- 10. The polishing pad of claim 8 wherein, the additional adhesive is a pressure sensitive adhesive that is hydrophobic.
CROSS REFERENCE TO RELATED APPLICATION
This application claims the benefit of U.S. Provisional Patent Application Serial No. 60/156,614 filed on Sep. 29, 1999.
Semiconductor wafers having integrated circuits fabricated thereon must be polished to provide a very smooth and flat wafer surface which in some cases may vary from a given plane by as little as a fraction of a micron. Such polishing is usually accomplished in a chemical-mechanical polishing (CMP) operation which utilizes a chemically active slurry that is buffed against the wafer surface by a polishing pad.
U.S. Pat. No. 5,893,796 discloses a polishing pad for use with a polishing fluid, the polishing pad having, a polishing layer and a window in an opening through the polishing layer. The window transmits an optical beam for detection of the presence or absence of a thickness of material being removed from a semiconductor wafer by a CMP polishing operation. One of the problems to be faced is to prevent polishing fluid from leaking beyond the polishing layer and, thereby, causing optical interference with the optical beam being transmitted by the window. To prevent leakage, an adhesive seal is imbedded in the opening between the window and the fluid impermeable layer. However, the seal can be defective by having a leakage path due to a gap in the adhesive seal. Further, the polishing pad is thin and, thereby, is easily bent, which tends to develop a crack or separation of the adhesive from the sides of the opening, due to bending during routine handling of the polishing pad, or due to exertion of polishing pressure during use of the polishing pad, or due to small voids or gaps in the adhesive.
US Referenced Citations (6)
Number |
Name |
Date |
Kind |
5893796 |
Birang et al. |
Apr 1999 |
A |
6077783 |
Allman et al. |
Jun 2000 |
A |
6102775 |
Ushio et al. |
Aug 2000 |
A |
6146248 |
Jairath et al. |
Nov 2000 |
A |
6190234 |
Swedek et al. |
Feb 2001 |
B1 |
6213845 |
Elledge |
Apr 2001 |
B1 |
Foreign Referenced Citations (1)
Number |
Date |
Country |
0 663 265 |
Jul 1995 |
EP |
Provisional Applications (1)
|
Number |
Date |
Country |
|
60/156614 |
Sep 1999 |
US |