Patent ID: 9136377
Filing Date: 2015-09-15
Classification: H01L

Abstract:
1. A method for fabricating a high density trench-gated MOSFET array device comprising: a) providing a semiconductor substrate, forming an epitaxial layer on the semiconductor substrate; b) creating an array of active trenches in a MOSFET array area and a pickup trench in a gate pickup area with the active trenches and the pickup trench extending a predetermined total trench depth (TCD) from a top surface of the epitaxial layer into the epitaxial layer; c) creating an array of active nitride-capped trench gate stacks (ANCTGS) upon the active trenches, a pickup nitride-capped trench gate stack (PNCTGS) upon the pickup trench, and implanting into the epitaxial layer body regions and source regions, wherein: and wherein the PNCTGS comprises a stack of: thereby forming a MOSFET array in the MOSFET array area and a gate pickup structure in the gate pickup area; and d) depositing a patterned dielectric region atop the MOSFET array and the gate pickup structure and a patterned metal layer atop the patterned dielectric region wherein the patterned metal layer forms a number of self-aligned source and body contacts through the inter-ANCTGS separations in the MOSFET array area and a self-aligned gate contact through the center gap between said pair silicon nitride caps in the gate pickup structure area; and wherein creating the array of active nitride-capped trench gate stacks (ANCTGS) upon the active trenches, and the pickup nitride-capped trench gate stack (PNCTGS) upon the pickup trench further comprises: Forming a polysilicon gate recess inside each active trench and the pickup trench from a top surface of a hard mask; Depositing then dry etching a silicon nitride layer to form a silicon nitride cap seed that just fills up the gate recess in each active trench and only partially fills up the gate recess in the pickup trench; Stripping of the hard mask then depositing and dry etching a second silicon nitride layer to form a silicon nitride cap on top of each active trench gate and a pair silicon nitride cap on top of the pickup trench gate.