Apparatus and method for plasma etching

Abstract

A plasma etching apparatus capable of performing processing with excellent in-plane uniformity on an object to be processed having a large diameter is provided. The present invention provides a plasma etching apparatus including a processing chamber 13 which performs plasma processing on an object to be processed 1, a first processing gas supply source 40, a second processing gas supply source 50, a first gas inlet 65-1 which introduces a processing gas into the processing chamber, second gas inlets 65-2 which introduce the processing gas into the processing chamber, flow rate regulators 42 and 53 which regulate the flow rate of the processing gas and a gas shunt 60 which divides the first processing gas into a plurality of portions, wherein at least two gas pipes branched by the shunt 60 are provided with the first gas inlet 65-1 or second gas inlets 65-2 and merging sections 63-1 and 63-2 are provided between the shunt 60 and the first gas inlet 65-1 and between the shunt 60 and the second gas inlets 65-2 for merging the second processing gas.

Description

[0001] The present application claims priority from Japanese application JP2003-206042 filed on Aug. 5, 2003, the content of which is hereby incorporated by reference into this application. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a plasma etching apparatus for processing an object to be processed such as a semiconductor wafer, and a plasma etching method using the plasma etching apparatus. [0004] 2. Description of the Related Art [0005] In a semiconductor chip manufacturing process, a plasma etching apparatus using reactive plasma to process an object to be processed such as a semiconductor wafer is conventionally used. [0006] Here, with reference to across-sectional view of an object to be processed shown in FIG. 13, etching for forming a poly-silicon (Poly-Si) gate electrode of an MOS (Metal Oxide Semiconductor) transistor (hereinafter referred to as “gate etching”) will be explained as one example of a plasma etching pr...

AI Technical Summary

Benefits of technology

[0033] Furthermore, the present invention calculates the amount of deposition in the processing chamber 13 from the photoreception result of plasma emission, estimates the amount of generated ions and radicals from the calculation result to thereby adjust the composition and / or flow rate of the processing gas 21 introduced from the plurality of inlets.

Problems solved by technology

Gate etching is performed using the plasma etching apparatus as described above, but with the recent increase in the diameter of the object to be processed 1, it is becoming more difficult to secure the in-plane uniformity of etching rates or the in-plane uniformity of the gate width 8 over a wide area of the object to be processed 1.

For example, in an area with a high etching rate, the concentration of reaction products including silicon deriving from the poly-silicon film 4 becomes higher than in areas with a low etching rate, which may cause in-plane nonuniformity of CD shifts.

This may also cause in-plane nonuniformity of CD shifts.

When these depositions fall off and attach to the surface of the object to be processed 1, the yield of volume production of semiconductor devices is deteriorated.

This art is capable of changing the in-plane uniformity of the etching rate, but since the processing gas introduced from the respective inlets has the same composition, it cannot sufficiently adjust the in-plane uniformity of ions and radicals.

However, since the position of introducing the reaction product gas as the reaction inhibition gas is limited to one inlet, this structure has constraints on the improvement of in-plane uniformity of the etching rate.

However, on the contrary, when the etching rate in the outer regions of the object to be processed is greater than the etching rate in the central part, this structure requires gas pipes to be replaced, so it is unable to respond to the demand quickly.

It also has the disadvantage that a supply source of the reaction product gas and piping system need to be added in addition to the gas used for normal etching to the apparatus.

Images