| 摘要 |
PURPOSE:To prevent wirings from being disconnected in a contact hole by forming the contact hole 15, then selectively etching a PSG film an oxide film, forming a steplike structure, and heat treating it to form the tapered contact hole as a whole. CONSTITUTION:When a contact hole 15 is formed and wet etched with an etchant of fluoric acid, a PSG and an SiO2 are selectively etched, the portion 12a of the SiO2 film is exposed, projected in the state that no SPG exists thereon, and the insulating film of a 2-layer structure that the PSG an the SiO2 are erected is formed in a steplike structure. Then, when it is wet melted in an atmosphere added with stream to N2 at 1,050 deg.C for 10min, the PSG is melted, and the melted PSG is extended also on the projection 12a of the SiO2 film due to the surface tension between the PSG and the SiO2 film having good bondability so that the shape of the contact hole is tapered from the bottom toward the upper portion.
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