| 摘要 |
PURPOSE: To form contacts for electrical connection having various widths, by preventing unnecessary over-etching by simultaneously etching a plurality of via holes by using such an etchant that can be stopped by an etch stopping layer and can pass through a dielectric layer. CONSTITUTION: After a low-dielectric material layer 56 is stuck to the surface of a device and the layer 56 is flattened, a photoresist mask 57 having openings 58 and 60 above base contacts 36 and sub-collector reach through areas 28, respectively, is formed, and the layer 56 is etched by anisotropic RIE. Via holes 58 and 60 having different depths can be formed by using a polycrystalline silicon layer 54 as an etch stop layer. In addition, the holes 58 and 60 can be brought into contact with the contacts 36 and an area 26 without causing over- etching by removing layers 54, 52, and 48 by performing RIE using appropriate plasma and, therefore, the holes 58 and 60 can be made to function as electrical contacts to each area through processes.
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