Si etching method and device

Abstract

To achieve a high aspect ratio and improvement of the etching rate in Si etching. Mixture gas of Cl2 / O2 / NF3is introduced from a process gas supply part 42 into a chamber 10 as an etching gas, and etching is performed under the condition, where the residence time is about 180 nsec or larger. High-frequency near 60 MHz is applied from a first high-frequency power source 58 to an upper electrode 30 at a specified power level. Further, a high frequency near 2MHz is applied from a second high-frequency power source 64 to a lower electrode (susceptor) 16 with a specified power level. The etching gas, discharged from a porous electrode plate or a shower head 36 of the upper electrode 30, is turned into a plasma during the glow discharge between the electrodes, and a Si wafer W is etched by radicals and ions generated in the plasma.

Description

technical field

[0001] The invention relates to a technique for etching Si (silicon), in particular to an etching method and device suitable for forming and processing small-diameter deep trenches on Si substrates or Si layers. Background technique

[0002] A trench separation method for separating elements in an LSI (Large Scale Integrated circuit) is generally an STI (Shallow Trench Isolation) method. In STI, a Si substrate is dry-etched using a resist layer or an insulating film as a mask to form relatively shallow grooves (grooves) with a depth of 1 μm or less. For this trench etching, a technique for controlling the depth and shape of the trench, especially the angle of the side wall (taper angle) is required.

[0003] At present, STI uses etching gas, mostly using mixed gas with Br (bromine element) as the basic raw material, typically HBr / O 2 mixed composition. Since the HBr pairs pass O 2 The oxide film (SiO 2 ) is relatively weak in attack, so it is easy to be ...

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