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US 8,575,016 B1Granted
Method for etching gate stack
AssigneeIntermolecular, Inc.
InventorsJohn Foster, Kim Van Berkel
Life of this patent
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Abstract
A method for etching a metal gate stack is provided. The method includes forming a gate stack on a substrate, where the gate stack includes a metal gate. A wet etch process is performed on the gate stack. The wet etch process includes submersing the substrate with the gate stack in an aqueous solution composed of a wet etchant and an oxidizer, removing the substrate from the solution and rinsing the solution from the etched gate stack.
Claims9
A method, comprising:
- forming a silicon dioxide pedestal on a surface of a substrate;
- forming a high-k dielectric film on the silicon dioxide pedestal;
- forming a metal film on the high-k dielectric film;
- forming a polysilicon film on the metal film;
- wherein the silicon dioxide pedestal, high-k dielectric film, metal film, and the polysilicon films collectively form a gate stack;
- preparing a solution of a wet etchant and an oxidizer;
- undercutting the gate stack by contacting the gate stack with the solution for a period of time, wherein each layer of the gate stack is contemporaneously exposed to the solution to etch side surfaces of each layer of the gate stack;
- and
- wherein the silicon dioxide pedestal, high-k dielectric film, metal film, and the polysilicon film have varying widths.
6 more elements
Dependencies are inferred from the claim text.