METHOD OF MANUFACTURING BUPOLAR AND CMOS TRANSISTOR ON COMMON SUBSTRATE

摘要

PURPOSE: To obtain excellent step coverage, namely, step coating on a metallic layer by performing isotropic wet etching after a vertical opening is formed by performing anisotropic dry etching on a double coating layer consisting of a first layer composed of undoped silicon oxide and a second layer composed of doped silicon dioxide formed on a substrate. CONSTITUTION: After a second layer 63 made of polycrystalline silicon is demarcated, undoped low-temperature silicon dioxide(LTO) is stuck to the entire upper surface of the layer 63 and boron/phosphorus-doped glass 65(BPSG) is stuck to the LTO. Then a contact opening is formed by completely etching the doped glass and undoped glass by performing reactive ion etching using a mask. After the contact opening is formed, the opening is further etched with a buffer hydrofluoric acid solution. Since the glass richly doped with phosphorus has etching selectivity of about 9:1 against the undoped glass in 10% hydrofluoric acid solution, the upper end section of the contact opening is smoothly rounded.