| US 7,452,777 B2 | ||
| Self-aligned trench MOSFET structure and method of manufacture | ||
| Christopher Boguslaw Kocon, Mountaintop, Pa. (US); and Nathan Lawrence Kraft, Pottsville, Pa. (US) | ||
| Assigned to Fairchild Semiconductor Corporation, South Portland, Me. (US) | ||
| Filed on Jan. 25, 2006, as Appl. No. 11/339,998. | ||
| Prior Publication US 2007/0173021 A1, Jul. 26, 2007 | ||
| Int. Cl. H01L 21/336 (2006.01) | ||
| U.S. Cl. 438—270 [438/197; 438/299; 257/331; 257/E29.146; 257/E29.156] | 22 Claims |
| 13. A method of forming a trench gate field effect transistor (FET) in a semiconductor die comprising an active region wherein
active transistor cells are formed and a termination region surrounding the active region, the method comprising:
forming a well region in the active region and the termination region at the same time, the well region being formed in a
silicon region having a conductivity type opposite that of the well region;
simultaneously forming a plurality of active gate trenches in the active region, a non-active gate runner trench, and a non-active
termination trench in the termination region, the plurality of active gate trenches, the non-active gate runner trench, and
the non-active termination trench extending into and penetrating through the well region to thereby divide the well region
into a plurality of active body regions in the active region and a termination body region in the termination region;
forming a recessed active gate electrode in each active gate trench and a recessed gate runner electrode in the non-active
gate runner trench at the same time, the recessed active gate electrodes being electrically connected to the recessed gate
runner electrode;
defining an opening over the termination body region and an opening over the active region using a mask;
implanting dopants into the active body regions through the opening in the active region and into the termination body region
through the opening over the termination body region, thereby forming a first region in each active body region and in the
termination body region, the first regions having a conductivity type opposite that of the well region; and
recessing exposed surfaces of all first regions using a silicon etch to form a bowl-shaped silicon recess having slanted walls
and a bottom protruding through the first region such that portions of each first region remain in a corresponding active
body region, the remaining portions of the first region in the active body regions forming source regions which are self-aligned
to the active gate trenches.
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