Patent Number: 048779628
Section: claims

1. An ion implantation method comprising: positioning a generally planar silicon substrate having a (100) orientation in a first position in which said substrate is tilted with respect to an incident ion beam and said substrate is rotated in its own plane by an angle of 15.degree. to 75.degree. to a first position from a position in which the (110) crystal planes of said substrate are aligned with said ion beam;  irradiating said substrate in said first position with the ion beam with a dose of ions equal to approximately 1/4 of the total desired dose of ions to be implanted into said substrate;  rotating said substrate in its plane to a second position which is 90.degree. removed from the first position and irradiating said substrate with said ion beam with a dose of ions equal to approximately 1/4 of the total desired dose of ions;  rotating said substrate in its plane to a third position which is 180.degree. removed from the first position and irradiating said substrate with said ion beam with a dose of ions equal to approximately 1/4 of the total desired dose of ions; and  rotating said substrate in its plane to a fourth position which is 270.degree. removed from the first position and irradiating said substrate with said ion beam with a dose of ions equal to approximately 1/4 of the total desired dose of ions. 2. An ion implantation method as claimed in claim 1 wherein said angle of said first position is about 45.degree.. 3. An ion implantation method as claimed in claim 1 wherein said substrate is tilted with respect to said ion beam by about 7.degree..