Metal Gate Isolation Structure to Reduce Voids and Shorts
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Solution Overview
Problem
As the minimum feature sizes in semiconductor devices are reduced, issues such as isolation void defects and drain to gate shorts arise, leading to reduced processing yield and potential device performance issues.
Innovation Solution
The method involves forming isolation features with specific shapes and air gap configurations within trenches, using techniques such as etching and conformal deposition of isolation materials, to minimize voids and improve device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional isolation features are formed without air gaps, then processing yield is reduced due to void defects, but device performance is compromised due to drain to gate shorts
Solution Approach 1:
The patent applies local quality by creating air gaps only in specific regions of the isolation feature where they provide benefit. The air gaps are formed between the isolation material and the trench walls at selected locations, allowing the isolation feature to have different properties in different regions - solid contact in some areas for mechanical stability, and air gaps in other areas for electrical isolation and void prevention.
Solution Approach 2:
The patent utilizes porous material structure by incorporating air gaps within the isolation feature. The isolation feature becomes a composite structure with solid isolation material regions and air void regions, creating a porous-like architecture that prevents void defects while maintaining electrical isolation properties.
2Productivity
If minimum feature sizes are reduced to increase integration density, then more components can be integrated into a given area, but isolation void defects and drain to gate shorts increase
Solution Approach 1:
The patent applies segmentation by dividing the isolation feature into distinct segments - solid isolation material segments and air gap segments. This segmentation allows the isolation feature to function both as a structural element and as an electrical isolator, preventing the defects that typically arise when minimizing feature sizes for higher integration density.
Solution Approach 2:
The patent uses composite material structure by combining isolation material with air gaps to create a composite isolation feature. This composite structure leverages the advantages of both solid material (mechanical support, structural integrity) and air (electrical isolation, void prevention), enabling reliable operation at reduced minimum feature sizes.
Data Source
AI summary
Devices with isolated metal structures and methods of fabrication are provided. A method for isolating a metal gate includes forming a gate line over a semiconductor substrate; patterning a mask over the gate line, wherein an opening in the mask is located over a region of the gate line to be removed; performing an etching process through the opening to form a trench; and forming an isolation feature in the trench, wherein the isolation feature is selectively formed with no air gap, with a small air gap, or with a full air gap.