Apparatus and method for pulsed plasma processing of a semiconductor substrate

Patent 5983828 Issued on November 16, 1999. Estimated Expiration Date:

October 8, 2016. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

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Inventor

Savas, Stephen E.

Assignee

Mattson Technology, Inc.

Application

No. 727209 filed on 10/08/1996

US Classes:

118/723I, Radio frequency antenna or radio frequency inductive coil discharge means118/723IR, Producing energized gas remotely located from substrate156/345.48, With radio frequency (rf) antenna or inductive coil gas energizing means216/68, Using coil to generate the plasma315/111.51, Induction type427/569, Plasma (e.g., corona, glow discharge, cold plasma, etc.)438/714Including change in etch influencing parameter (e.g., energizing power, etchant composition, temperature, etc.)

Examiners

Primary: Breneman, R. Bruce
Assistant: Alejandro, Luz

Attorney, Agent or Firm

Wilson Sonsini Goodrich & Rosati

Foreign Patent References

2 105 729 GB 03/25/1983

International Class

C23C 016/00

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 (>1011 cm-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 etching. These ions are not deflected into sidewalls as readily as ions in conventional low energy etch processes due to reduced charge buildup and the relatively low duty cycle of power used to pulse ions toward the substrate surface.

Other References

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