Patent ID: 7682910

Claim:
A method of implanting ions into a semiconductor substrate comprising: providing a semiconductor substrate including a first semiconductor region and a second semiconductor region separated from each other by a first shallow trench isolation (STI) region; forming a patterned photoresist covering said second semiconductor region and not covering any of said first semiconductor region; implanting ions into said semiconductor substrate in a first direction at a first non-zero tilt angle from a surface normal of said semiconductor substrate, wherein said first direction is within an x-z plane of a Cartesian coordinate system having a z-axis along said surface normal, and an entirety of said first semiconductor region and an entirety of said second semiconductor region are shielded from said ions by said patterned photoresist; and implanting additional ions into said semiconductor substrate in a second direction at a second non-zero tilt angle from said surface normal of said semiconductor substrate and with said patterned photoresist on said semiconductor substrate, wherein said second direction is within said x-z plane of said Cartesian coordinate system, said first direction and said second direction are different, and said entirety of said second semiconductor region is shielded from said additional ions by said patterned photoresist, and wherein said additional ions are implanted to an entirety of a surface portion of said first semiconductor region.