| abstract |
(57) [Problem] To provide an element isolation method for a semiconductor device. SOLUTION: An insulating film for a mask is formed in a predetermined region on a semiconductor substrate 100, and a trench 110 having a predetermined depth is formed in the semiconductor substrate using the insulating film for the mask. An oxide film 10 is formed on the side wall of the insulating film for mask and the inner wall of the trench. 5 and 107, and a trench liner film 10 is formed thereon. 9 is formed. Next, a filling insulating film 111 is formed so as to completely fill the trench. Subsequently, the insulating film for the mask is removed. As described above, in the trench-type element isolation method, the oxide film is also formed on the side wall of the insulating film for the mask after the trench etching of the semiconductor substrate, thereby preventing a depression phenomenon which is likely to occur on both upper sides of the trench, A bird's beak type oxide film penetrating phenomenon occurring at an interface in contact with the mask insulating film is prevented, and a leakage current of the semiconductor device is reduced and suppressed, thereby improving a threshold voltage characteristic. |