Method for etching a wafer edge using a potassium-based chemical oxidizer in the presence of hydrofluoric acid
US6482749B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 10, 2000 |
| Grant date | Nov 19, 2002 |
| Priority date | — |
| Expiry date | Nov 17, 2020 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC11D2111/22
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A method for fabricating wafers is provided that uses a potassium-based oxidizer in the presence of hydrofluoric acid as the chemical etchant for etching the wafer edge. The potassium-based chemical etchant is preferably potassium permanganate KMnO4 that is mixed with hydrofluoric acid such that the ratio of hydrofluoric acid to potassium permanganate is between 2:1 and 4:1. The method for fabricating wafers initially divides a crystal ingot into a plurality of wafers before grinding the wafer edge to size and shape the wafer. The wafer can then be subjected to alkaline cleaning and acid etching. After a polysilicon layer is deposited on the wafer for gettering purposes and a silicon dioxide back seal layer, if any, is deposited, the wafer is then etched with the potassium-based chemical oxidizer in the presence of hydrofluoric acid to oxidize and remove the polysilicon layer and any silicon dioxide layer from the edge. The wafer is then rinsed and thermally annealed prior to undergoing edge polishing. In order to concentrate the potassium-based chemical etchant on the wafer edge, the opposed major surfaces can be covered, such as by being stacked in an alternating fashion with spa…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.