| 摘要 |
PURPOSE:To obtain a simple groove isolating structure with good reproducibility and its forming method, by forming recess parts in the surface of a semiconductor substrate for isolating elements, forming an insulating film on the side surface and the bottom surface of each recess part, and filling the inside of each recess with boron phosphorus glass (BPSG). CONSTITUTION:A thermal oxide SiO2 film 4 and a polycrystalline silicon film 6 are sequentially formed on a silicon substrate 1. Then, the polycrystalline silicon film 6 and the oxide film 4 are etched away. Recess parts 3 are formed in the surface of the substrate in order to isolate elements. A resist pattern 2 is removed. The side surface and the bottom surface of each recess part 3 and the surface of the polycrystalline silicon film 6 are thermally oxidized. The SiO2 film 4 is formed. Then, a BPSG film 7 is deposited in each recess part 3 and on the surface of the substrate. The reflow of the BPSG film 7 is performed. The BPSG film 7 is etched away until the polycrystalline silicon layer 6 is exposed and so that the layer remains in the recess part 3. The polycrystalline film 6 is removed. Thereafter, the surface of the BPSG film, which is embedded in the recess parts, is smoothly flattened owing to the surface tension by heat treatment of ordinary gate oxidation and the like.
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