Procedure for eliminating bubbles formed during reflow of a dielectric layer over an LDD structure
US5834346A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 14, 1997 |
| Grant date | Nov 10, 1998 |
| Priority date | — |
| Expiry date | Oct 14, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L21/76801
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A method for preventing bubble formation over source/drain active areas in p-channel MOSFETs is described. Bubble formation occurs when the source/drain areas and silicon containing gate electrodes are implanted with BF.sub.2.sup.+ molecule ions following an anisotropic LDD spacer etch using a plasma. It is found that the plasma causes the silicon surface to become prone to adsorption of BF.sub.2.sup.+ molecule ions during the source/drain/gate implantation. These adsorbed species are released and form bubbles during reflow of a subsequently deposited glass layer. The invention performs the spacer etch only partially with the anisotropic plasma and completes the spacer formation with a wet etch. The active silicon and gate electrode surfaces are thus not damaged by the plasma. Consequently adsorption of BF.sub.2.sup.+ molecule ions is inhibited and bubble formation does not occur during reflow.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.