Chemical polishing of single crystal dielectrics
US3964942A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 16, 1970 |
| Grant date | Jun 22, 1976 |
| Priority date | — |
| Expiry date | Oct 16, 1990 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D99/00
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A polishing method for single crystal dielectrics such as sapphire and magnesium spinel is disclosed. A single crystal wafer of sapphire or magnesium spinel is immersed in a mixture of sulphuric and phosphoric acid in a range of mixtures of 9 parts sulphuric acid to 1 part phosphoric acid to 1 part sulphuric acid to 9 parts phosphoric acid by volume while the mixture is held at a temperature in the range of 200.degree.-325.degree.C. The rate of polishing as well as the quality of polishing of the wafers of sapphire or magnesium spinel is orientation sensitive and polishing is achieved for magnesium spinel having the orientations (100) and (110). Polishing is achieved for sapphire having the orientations (0001), (1123), (1100), (1124), (1120) and (0112). A wafer to be polished is suspended in the heated solution and may be rotated slowly. Nonpreferential material removal rates of fractions of a micron per minute are obtained. Crystals of both sapphire and spinel having the above-mentioned orientations may be polished in a preferred temperature range of 250.degree.-300.degree.C. The preferred polishing mixture for sapphire is 1 part sulphuric acid to 1 part phosphoric acid by volume …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.