Process for fabricating a DRAM array having feature widths that transcend the resolution limit of available photolithography
US5013680A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 18, 1990 |
| Grant date | May 7, 1991 |
| Priority date | — |
| Expiry date | Jul 18, 2010 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S438/947
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A process for creating a DRAM array having feature widths that transcend the resolution limit of the employed photolithographic process using only five photomasking steps. The process involves the following steps: creation of a half-pitch hard-material mask that is used to etch a series of equidistanty-spaced isolation trenches in a silicon substrate; filling the isolation trenches with insulative material; creation of a hard-material mask consisting of strips that are 1-1/2F in width, separated by spaces that are 1/2F in width, that is used to etch a matrix of storage trenches; angled implantation of a N-type impurity in the storage trench walls; another anisotropic etch to deepen the storage trenches; deposition of a capacitor dielectric layer; deposition of a protective polysilicon layer on top of the dielectric layer; removal of the dielectric layer and the protective polysilicon layer at the bottom of each storage trench with a further anisotropic etch; filling the storage trenches with in-situ-doped polysilicon; planarization down to the substrate level; creation of an access gate on opposite sides of each storage trench, in addition to wordlines which interconnect gates with…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.