Self-aligned trench MOSFET structure and method of manufacture
First Claim
1. A method of forming a trench gate field effect transistor (FET) in a semiconductor die comprising an active region for housing active transistor cells 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 and a non-active termination trench in the termination region, the plurality of active gate trenches and the non-active termination trench extending into and penetrating through the well region to there by divide the well region into a plurality of active body regions in the active region and a termination body region in the termination region;
using a mask, forming an opening over the termination body region and an opening over the active region;
implanting dopants into the active body regions through the opening over 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 each first region such that portions of each first region remain in a corresponding active body region, the remaining portions of the first regions in the active body regions forming source regions which are self-aligned to the active gate trenches.
7 Assignments
0 Petitions
Accused Products
Abstract
PATENT A trench gate FET is formed as follows. A well region is formed in a silicon region. A plurality of active gate trenches and a termination trench are simultaneously formed in an active region and a termination region of the FET, respectively, such that the well region is divided into a plurality of active body regions and a termination body region. Using a mask, openings are formed over the termination body region and the active body region. Dopants are implanted into the active body regions and the termination body region through the openings thereby forming a first region in each active and termination body region. Exposed surfaces of all first regions are recessed so as to form a bowl-shaped recess having slanted walls and a bottom protruding through the first region such that remaining portions of the first region in each active body region form source regions that are self-aligned to the active gate trenches.
40 Citations
22 Claims
-
1. A method of forming a trench gate field effect transistor (FET) in a semiconductor die comprising an active region for housing active transistor cells 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 and a non-active termination trench in the termination region, the plurality of active gate trenches and the non-active termination trench extending into and penetrating through the well region to there by divide the well region into a plurality of active body regions in the active region and a termination body region in the termination region;
using a mask, forming an opening over the termination body region and an opening over the active region;
implanting dopants into the active body regions through the opening over 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 each first region such that portions of each first region remain in a corresponding active body region, the remaining portions of the first regions in the active body regions forming source regions which are self-aligned to the active gate trenches. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
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. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22)
-
Specification