| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method of a semiconductor device capable of preventing the deterioration of various characteristics in a low breakdown voltage region and a high breakdown voltage region, even when trench separation is employed especially in connection with the microfabrication of the low breakdown voltage region, in the semiconductor device having a low breakdown voltage transistor and a high breakdown voltage transistor having different thicknesses of gate insulating films. SOLUTION: Separation in the high breakdown voltage region is effected by LOCOS separation 13 with a separating end having a smooth bird's beak configuration, and separation in the low breakdown voltage region is effected by trench separation 6 suitable for the microfabrication. The low breakdown voltage region is protected by a silicone nitride film 7 upon forming a thick thermal oxidation film 16 of the high breakdown voltage region, whereby the film 16 is formed separately from a thin thermal oxidation film 19 of the low breakdown voltage region. Accordingly, the semiconductor device and its manufacturing method can prevent the deterioration of various characteristics in both regions even when the trench separation is adopted especially in connection with the microfabrication of the low breakdown voltage region. COPYRIGHT: (C)2005,JPO&NCIPI
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