US 5,690,781 AGranted

Plasma processing apparatus for manufacture of semiconductor devices

AssigneeNEC Corporation

InventorsKazuyoshi Yoshida, Hidenobu Miyamoto

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Abstract

A plasma processing apparatus comprises a reaction chamber to hold a high-density plasma and having a dielectric plate window, a spiral coil placed outside the reaction chamber and close to the dielectric window, and a lower electrode which holds a wafer to be processed in place and installed in the reaction chamber facing the dielectric plate. A first radio frequency current supply to the coil, a mechanism for varying the distance between the coil and the dielectric plate window, and a second radio frequency voltage supply to the lower electrode is provided. Excellent uniformity of the ion current density of the plasma and hence etching rate is achieved by making the thickness of a central part of the dielectric plate window thicker than its peripheral parts. Also, the uniformity of the plasma and the etching rate is achieved by making the induction field produced by the coil axially symmetrical about the axial center of the reaction chamber. The etching profile and the material etching selectivity are controlled by moving the coil in the axial direction of the coil.

Claims11

Dependent claims

A plasma processing apparatus comprising:

a reaction chamber in which a plasma is generated, said chamber having a dielectric plate with an inner main surface and an outer main surface, said inner main surface facing the interior of said chamber, said chamber being electrically grounded except for said dielectric plate;
a spiral coil placed outside said reaction chamber and adjacent said outer main surface;
a radio frequency power source for supplying a first high frequency electrical current to said coil;
a tuning mechanism for electromagnetically matching said radio frequency power source and said coil;
at least one inlet for introducing a plurality of process gas into said vacuum reaction chamber;
a pressure controller for controlling the pressure of said process gas;
a lower electrode for receiving a wafer to be processed, said lower electrode being contained within said reaction chamber and positioned remote from said dielectric plate;
a mechanism for varying the distance between said dielectric plate and said spiral coil;
and
a second high frequency voltage supply connected to said lower electrode;
wherein said dielectric plate comprises a central portion with a constant first thickness, a circumferential portion with a constant second thickness, and a tapered portion between said central portion and said circumferential portion, said central portion of said dielectric plate having a diameter 0.2 to 0.4 times the diameter of said dielectric plate, and said first thickness being 2 to 5 times said second thickness.

8 more elements

Dependencies are inferred from the claim text.