FinFET Metal Gate Formation Using a Hanging Dummy Gate
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Solution Overview
Problem
In the semiconductor industry, the formation of FinFET devices faces challenges such as voids in the gate electrode layer, leading to defects and increased resistance in the metal gate structure due to shrinking feature sizes and difficulties in depositing material between closely spaced fins, which can result in incomplete coverage and voids, affecting the integrity and performance of the device.
Innovation Solution
The method involves forming a hanging dummy gate structure with a gate fill material that fills the gap between the dummy gate and isolation regions, reducing the risk of voids and allowing for a subsequent replacement with a metal gate, which includes forming a dielectric layer over the dummy gate, etching to create a gap, depositing gate fill material, and then replacing the dummy gate and fill material with a metal gate structure through controlled etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If material is deposited between closely spaced fins to form gate electrode, then gate coverage is improved, but voids and defects occur due to incomplete coverage
Solution Approach 1:
A gate fill material is introduced as an intermediary substance between the dummy gate electrode and the isolation region. This gate fill material fills the gap and prevents void formation, serving as a mediator that resolves the coverage issue without requiring direct deposition between closely spaced fins
Solution Approach 2:
The gate fill material is deposited before the metal gate structure is formed. This preliminary action ensures that the gap is filled and voids are prevented before the critical metal gate deposition step, improving subsequent manufacturing yield
2Productivity
If feature size is reduced to increase integration density, then more components fit in given area, but voids and defects increase in gate electrode layer
Solution Approach 1:
The gate fill material serves as a mediator that enables continued scaling to smaller feature sizes by preventing void formation that would otherwise occur at reduced dimensions. This allows integration density to increase while maintaining gate electrode integrity
Solution Approach 2:
By preliminarily filling the gap with gate fill material before metal gate deposition, the method enables reliable manufacturing at smaller feature sizes where direct deposition would fail due to void formation
3Reliability
If dummy gate electrode is removed and replaced with metal gate, then device performance is improved, but voids and defects from previous steps are transferred to metal gate structure
Solution Approach 1:
The gate fill material acts as a protective intermediary that prevents void formation during the dummy gate removal and metal gate formation steps. By maintaining continuous material presence in the gap, it ensures the metal gate structure inherits no voids or defects from previous processing steps
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the likelihood of defects and high resistance in the metal gate structure by ensuring complete coverage and reduces leakage current by increasing the distance between the metal gate and source/drain regions, thereby enhancing the overall performance and reliability of FinFET devices.
Implementation Method 1
forming a dielectric layer over the dummy gate
Implementation Method 2
depositing gate fill material
Implementation Method 3
etching to create a gap
Data Source
AI summary
A method of forming a semiconductor device includes: forming a fin protruding above a substrate; forming isolation regions on opposing sides of the fin; forming a dummy gate electrode over the fin; removing lower portions of the dummy gate electrode proximate to the isolation regions, where after removing the lower portions, there is a gap between the isolation regions and a lower surface of the dummy gate electrode facing the isolation regions; filling the gap with a gate fill material; after filling the gap, forming gate spacers along sidewalls of the dummy gate electrode and along sidewalls of the gate fill material; and replacing the dummy gate electrode and the gate fill material with a metal gate.