| 摘要 |
<p>A method for forming a semiconductor device isolation region including steps of forming a first silicon oxide film (2) on a silicon substrate (1), depositing a first silicon nitride film (3) over the first silicon oxide film (2), and removing the first silicon oxide film (2) and first silicon nitride film (3) in a device isolation region (5) by using a resist pattern (4), which is formed by a one-time photolithographic step, as a mask so as to expose the surface of the silicon substrate, removing the resist pattern, and oxidizing the exposed surface of the silicon substrate so as to form a second silicon oxide film (4) having a smaller thickness than the first silicon oxide film and to deposit a second silicon nitride film (7), removing the second silicon nitride film (7) by anisotropic etching until the second silicon oxide film (4) is exposed in the device isolation region so as to make the second silicon nitride film remain as the side wall portion (7a,7b) of the silicon nitride film in only the opening side wall portion of the first silicon nitride film, etching the second silicon oxide film in the opening (8) of the first silicon nitride film on a self-aligning basis by using as etching masks the first silicon nitride film and the side wall portion (7a,7b) of the second silicon nitride film remaining on the opening side wall portion of the first silicon nitride film, and selectively carrying out oxidation so as to form a thick silicon oxide film (9) in the device isolation region. <IMAGE> <IMAGE> <IMAGE></p> |
