Apparatus and method for pulsed plasma processing of a semiconductor substrate
US5983828A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 8, 1996 |
| Grant date | Nov 16, 1999 |
| Priority date | — |
| Expiry date | Oct 8, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J2237/3345
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Apparatus and method for an improved etch process. A power source alternates between high and low power cycles to produce and sustain a plasma discharge. Preferably, the high power cycles couple sufficient power into the plasma to produce a high density of ions (>10.sup.11 cm.sup.-3) for etching. Preferably, the low power cycles allow electrons to cool off to reduce the average random (thermal) electron velocity in the plasma. Preferably, the low power cycle is limited in duration as necessary to prevent excessive plasma loss to the walls or due to recombination of negative and positive ions. It is an advantage of these and other aspects of the present invention that average electron thermal velocity is reduced, so fewer electrons overcome the plasma sheath and accumulate on substrate or mask layer surfaces. A separate power source alternates between high and low power cycles to accelerate ions toward the substrate being etched. In one embodiment, a strong bias is applied to the substrate in short bursts. Preferably, multiple burst occur during the average transit time for an ion to cross the plasma sheath and reach the substrate surface. Ions are pulsed toward the surface for etch…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.