Formation of wells utilizing masks in manufacturing semiconductor device

A method for manufacturing a semiconductor device, comprising:

• forming a first mask on a semiconductor substrate, said first mask having a first opening;
• forming a first layer well having first and second regions used to form a pair of MOS transistors by implanting first ion into said semiconductor substrate using said first mask as a mask;
• forming a second mask on said semiconductor substrate, said second mask having a second opening;
• and
• forming a second layer well located below said first layer well by implanting second ion into said semiconductor substrate using said second mask as a mask;
• wherein
• said first mask is formed in such a manner that said first ion, deflected by a first inner wall surface of said first opening of said first mask, is supplied to said first region;
• and
• said second mask is formed in such a manner that said second ion, deflected by a second inner wall surface of said second opening of said second mask, is supplied to said second region.

A method for manufacturing a semiconductor device, comprising:

• providing a semiconductor substrate having a first, a second and a third regions, said first, said second and said third regions arranged in that order on a line;
• forming a first mask on said semiconductor substrate, said first mask having a first opening;
• implanting first ion into said first, said second and said third regions to form a first layer well using said first mask, so that said first and said third regions also include said first ion deflected by a first inner wall surface of said first opening of said first mask;
• forming a second mask on said semiconductor substrate, said second mask having a second opening;
• and
• implanting second ion into said second and third regions to form a second layer well using said second mask, so that said second region also includes said second ion deflected by a second inner wall surface of said second opening of said second mask.