Partial implantation method for semiconductor manufacturing
View Patent ↗Disclosed herein is a partial implantation method for manufacturing semiconductor devices. The method involves implantation of dopant ions at different densities into a plurality of wafer regions, including first and second regions, defined in a wafer by means of a boundary line. In the method, first, second and third implantation zones are defined. The first implantation zone is the remaining part of the first region except for a specific part of the first region close to the boundary line, the second implantation zone is the remaining part of the second region except for a specific part of the second region close to the boundary line, and the third implantation zone is the remaining part of the wafer except for the first and second implantation zones. Then, dopant ions are implanted into the first implantation zone at a first density, into the second implantation zone at a second density different from the first density, and into the third implantation zone at a third density that is a midway value between the first and second densities.
1. A partial implantation method to implant dopant ions at different densities into a center region and a peripheral region defined in a wafer by means of a circular boundary line, the method comprising:
defining a first region at an upper side of a horizontal line as a tangent line of the circular boundary line and a second region at a lower side of the horizontal line;
implanting dopant ions at a first density into a first implantation zone as a remaining part of the first region except for a specific part of the first region close to the horizontal line, at a second density different from the first density into a second implantation zone as a remaining part of the second region except for a specific part of the second region close to the horizontal line, and at a third density between the first and second densities into a third implantation zone as remaining part of the wafer except for the first and second implantation zones; and
repeatedly implanting the ions while intermittently rotating the wafer within an angular range of 360°,
wherein a slope of the density of dopants in the third implantation zone can be adjusted by varying the area of a least one of the first and second implantation zones.
2. The method as set forth in claim 1 , wherein the repeated implanting of the ions while intermittently rotating the wafer is performed until the wafer is rotated beyond at least the angular range of 360°.
3. The method as set forth in claim 1 , wherein the wafer is intermittently rotated by an angle of less than 180° during the implantation of the dopant ions.
4. The method as set forth in claim 1 , wherein the first implantation zone has an area corresponding to about 98% of the area of the first region.
5. The method as set forth in claim 1 , wherein the second implantation zone has an area corresponding to about 98% of the area of the second region.
6. The method as set forth in claim 1 , wherein:
the first density of the dopant ions implanted in the first implantation zone is lower than the third density of the dopant ions implanted in the third implantation zone; and
the second density of the dopant ions implanted in the second implantation zone is higher than the third density of the dopant ions implanted in the third implantation zone.
7. The method as set forth in claim 6 , wherein:
the first density is lower than the third density by about 5%; and
the second density is higher than the third density by about 5%.