Method for forming masks comprising silicon nitride and novel mask structures produced thereby
US4002511A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 16, 1975 |
| Grant date | Jan 11, 1977 |
| Priority date | — |
| Expiry date | Apr 16, 1995 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S148/117
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
In the fabrication of integrated circuits, a method is provided for forming masking structures comprising silicon nitride which avoids the stresses and dislocations associated with direct silicon nitride masking as well as the "bird's beak" problems associated with silicon dioxide-silicon nitride composite mask structures. The mask is formed by first forming a silicon dioxide mask having at least one opening through which the substrate is exposed. Then, a mask comprising silicon nitride is formed on the first mask; this mask has at least one opening laterally smaller than the openings in the first mask and respectively in registration with at least some of the openings in said first mask. Thus, the second mask contacts and covers a portion of the exposed silicon substrate under each of the registered openings. The masked silicon substrate is subjected to a processing step such as oxidation, etching or diffusion which alters the characteristics of those portions of the silicon substrate remaining exposed. During this processing step a second mask serves as a barrier mask.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.