Abstract:
PROBLEM TO BE SOLVED: To provide a method for forming a BiCMOS device comprising a deep sub-collector region and a self-aligning mark. SOLUTION: There are provided a step (a) where a layer with a first pattern comprising a thick dielectric material is formed on the surface of a material stack formed on a semiconductor substrate through lithography, a step (b) where high energy/high dose injection is performed via an opening of the first layer as well as the material stack to form at least one deep sub-collector region in the semiconductor substrate, a step (c) where a layer with a second pattern (photoresist or dielectrics) is formed by lithography, and a step (d) where etching is performed through the material stack for forming an alignment mark in the semiconductor substrate, which is positioned below, using the layer with the first pattern as an alignment mark mask.
Abstract:
PROBLEM TO BE SOLVED: To provide a method for anisotropic etching of a nitride layer on a substrate. SOLUTION: In this etching process, an etchant gas containing fluorohydrocarbon rich in hydrogen, oxidant and carbon source is used. It is preferable that the fluorohydrocarbon rich is hydrogen be CH3 or CH2 F2 , the carbon source be CO2 or CO, and the oxidant be O2 . It is preferable that the fluorohydrocarbon exsist in a gas of about 7-35 vol.%, the oxidant exsist in a gas of about 1-35 vol.%, and the carbon source exsists in a gas of about 30-92 vol.%.