Bottom Isolation Structure for 3D Semiconductor Leakage Blocking
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Solution Overview
Problem
The 3D-stacked semiconductor devices face challenges with current leakage due to disconnection between the lowermost inner spacer and the bottom isolation structure, leading to degraded device performance and reduced process margin.
Innovation Solution
A bottom isolation structure is formed with an inner spacer residue and an inner isolation structure, both made of different materials, to prevent current leakage by ensuring a continuous connection without disconnection, using silicon nitride for the inner spacer residue and silicon oxide for the inner isolation structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the inner spacer is disconnected from the bottom isolation structure, then the manufacturing process is simpler, but current leakage occurs and device performance degrades
Solution Approach 1:
The patent introduces an inner spacer residue as an intermediary element that connects the inner spacer to the bottom isolation structure. This residue acts as a bridge that ensures continuous electrical isolation while maintaining manufacturing feasibility. The inner spacer residue is specifically positioned at the interface between the inner spacer and the bottom isolation structure to prevent current leakage paths.
Solution Approach 2:
The patent applies preliminary action by forming the inner spacer residue before finalizing the bottom isolation structure. This ensures that the connection path is established in advance, preventing current leakage issues that would otherwise require complex post-processing corrections. The inner spacer residue is formed as part of the initial isolation structure fabrication sequence.
2Ease of manufacture
If the inner spacer and inner isolation structure use the same material composition, then the manufacturing process is simpler, but current leakage prevention is insufficient
Solution Approach 1:
The patent applies local quality by using different material compositions for different parts of the isolation structure. Specifically, the inner spacer residue uses a first material composition while the bottom isolation structure uses a second material composition. This local differentiation ensures optimal electrical isolation properties at the critical interface region where current leakage prevention is most needed.
Solution Approach 2:
The patent employs composite materials by combining different material compositions in the isolation structure. The inner spacer residue and bottom isolation structure use different materials with complementary properties, creating a composite structure that provides superior current leakage prevention compared to a single-material approach. This composite design allows each material to contribute its optimal properties to the overall isolation function.
Data Source
AI summary
Provided is a semiconductor device which includes: a substrate; a channel structure on the substrate; a source/drain pattern connected to the channel structure; a gate structure on the channel structure; an inner spacer structure comprising an inner spacer between the source/drain pattern and the gate structure, and an inner spacer residue connected to the inner spacer structure; and an inner isolation structure between the inner spacer residue and a bottom surface of the source/drain pattern.