Metal Gate Electrode Crown Structure for Narrow Trench Filling

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Solution Overview

Problem

Existing technologies face challenges in filling the recessed portion of a metal gate structure in transistor devices as dimensions shrink, leading to inefficiencies in forming the gate electrode.

Innovation Solution

A gate trench is formed over a channel region and sequentially filled with a gate dielectric, work function metal, and electrode metal, with the electrode metal being patterned to form a gate electrode in a 'crown' shape, avoiding the need to refill a relatively narrow space.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the minimum feature size is reduced to increase integration density, then more components can be integrated into a given area, but the difficulty of filling narrow spaces in the gate structure increases

Engineering Contradiction:

Improveintegration densityVSAvoiddifficulty of filling narrow spaces

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

Instead of filling the recessed portion from the top down (conventional approach), the patent forms the gate electrode by depositing material conformally on the sidewalls and then selectively removing the recessed portion, effectively building the structure from the sides inward. This inversion of the filling approach eliminates the difficulty of refilling narrow recessed spaces while maintaining small feature sizes for high integration density.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If the recessed portion of the metal gate structure is refilled with gate electrode material, then the gate electrode can be formed, but the process becomes increasingly challenging as dimensions shrink

Engineering Contradiction:

Improvegate electrode formationVSAvoidprocess complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent performs preliminary conformal deposition of the gate electrode material on the sidewalls of the recessed portion before attempting to fill the recess. This preliminary action ensures that the electrode material is already in position on the critical surfaces, eliminating the need for subsequent refilling operations and simplifying the overall process as dimensions shrink.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent extracts or removes the problematic recessed portion of the metal gate structure after conformal deposition, rather than attempting to refill it. This extraction approach eliminates the manufacturing challenges associated with refilling narrow spaces while preserving the beneficial conformally deposited electrode material on the sidewalls.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS12532529B2Semiconductor devices and methods of manufacturing thereof

Publication Date: 2026.01.20 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method for fabricating semiconductor devices is disclosed. The method includes forming a gate trench over a semiconductor channel, the gate trench being surrounded by gate spacers. The method includes sequentially depositing a work function metal, a glue metal, and an electrode metal in the gate trench. The method includes etching respective portions of the electrode metal and the glue metal to form a gate electrode above a metal gate structure. The metal gate structure includes a remaining portion of the work function metal and the gate electrode includes a remaining portion of the electrode metal. The gate electrode has an upper surface extending away from a top surface of the metal gate structure.