Single electrode U-MOSFET random access memory
US4462040A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 30, 1980 |
| Grant date | Jul 24, 1984 |
| Priority date | — |
| Expiry date | Mar 30, 2000 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D84/01
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method for making highly dense, dielectrically isolated, U-shaped MOSFET. In a preferred method a monocrystalline silicon P substrate with a N+ layer thereon, a P layer on the N+ layer and a N+ layer on the P layer is provided. A pattern of U-shaped openings is formed in the body through to the P substrate by the reactively ion etching technique. This pattern of openings is filled with an insulator material, such as silicon dioxide. A conductive layer of N+ doped polycrystalline silicon is deposited on the bare surface of this silicon body. Openings are formed in the polycrystalline silicon over the silicon dioxide filled openings. A silicon dioxide layer is then grown by, for example, thermal oxidation over the polycrystalline silicon layer. Reactively ion etching is used to produce substantially U-shaped openings through the layers over the P substrate and into the P substrate to substantially bisect the regions of monocrystalline silicon. This etching step forms two storage cells in the monocrystalline silicon areas and a bit line for each column of cells in the polycrystalline silicon layer. A silicon dioxide gate insulator is grown on the monocrystalline silicon surfaces of …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.