Method for forming a void-free tungsten-plug contact in the presence of a contact opening overhang
US5654234A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 29, 1996 |
| Grant date | Aug 5, 1997 |
| Priority date | — |
| Expiry date | Apr 29, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L21/28556
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A method for the fabrication of an ohmic, low resistance contact to silicon is described using a CVD deposited tungsten plug provided with Ti/TiN barrier metallurgy. The method provides for a glass insulator layer deposited on the silicon. After the glass is flowed to planarize its surface, contact holes are patterned in the glass exposing the silicon substrate. The Ti/TiN barrier metallurgy is deposited by sputtering which, because of inferior edge coverage, results in a sidewall with a negative taper. Subsequent deposition of the tungsten results in a tungsten plug with an exposed void. The method taught by this invention deposits first a thin layer of tungsten whose thickness is governed by the amount of overhang caused by the tapered sidewall. An anisotropic dry etch step is then performed to achieve a vertical sidewall of tungsten. The remaining tungsten is then deposited to fill the contact opening without the occurrence of voids.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.