Composite Airgap Spacer Etch Stop for Semiconductor Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As semiconductor devices miniaturize, there is a need for transistors with higher drive currents, and low-k dielectric materials help reduce unintended device capacitance, but air gap spacers in semiconductor devices can lead to shorts due to conductive material filling passages within the spacers during manufacturing.
Innovation Solution
A method of forming a semiconductor device with a composite dielectric spacer including an air gap, where a conformal dielectric material encloses the air gap and an etch-resistant cap material is used to protect the spacer during contact formation, reducing the risk of shorts by maintaining the integrity of the spacer's solid sidewalls and upper surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If air gap spacers are used to reduce device capacitance, then device capacitance is reduced, but the spacers may develop void openings during etch processing that lead to shorts
Solution Approach 1:
The patent applies composite materials by creating a composite dielectric spacer that combines air gap regions with solid dielectric material regions. The spacer includes an air gap portion for reducing capacitance and a solid dielectric cap portion that protects against void openings during etch processing. This composite structure resolves the contradiction by maintaining the low-k dielectric benefits while adding protective solid material to prevent shorts.
Solution Approach 2:
The patent segments the dielectric spacer into distinct functional regions: an air gap portion (first dielectric material) for capacitance reduction and a solid dielectric cap portion (second dielectric material) for structural protection. This segmentation allows each region to perform its specific function optimally - the air gap provides low-k properties while the solid cap prevents etch-induced void openings.
2Reliability
If conformal dielectric material is deposited to enclose the air gap, then spacer integrity is improved, but the upper portion of the spacer opening requires additional recessing and cap material formation
Solution Approach 1:
The patent applies preliminary action by forming the conformal dielectric material layer that encloses the air gap before completing the spacer formation process. This preliminary enclosure of the air gap in solid dielectric material protects it during subsequent processing steps, preventing void openings while the additional recessing and cap material formation are completed.
Data Source
AI summary
A semiconductor device that includes a gate structure on a channel region of a semiconductor device. Source and drain regions may be present on opposing sides of the channel region. The semiconductor device may further include a composite gate sidewall spacer present on a sidewall of the gate structure. The composite gate sidewall spacer may include a first composition portion having an air gap encapsulated therein, and a second composition portion that is entirely solid and present atop the first composition portion.