Self-Aligned Backside Contact Structure for Nanometer Source/Drain Alignment
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Solution Overview
Problem
The formation of backside contact structures in semiconductor devices is complicated by substrate warpage and etching variations, leading to misalignment and difficulties in connecting backside contact structures to source/drain regions in nanometer-scale dimensions, especially in 3D-stacked semiconductor devices.
Innovation Solution
A self-aligned backside contact structure is formed by creating a placeholder structure and using backside spacers to precisely align the contact structure with the source/drain region, allowing for accurate connection and improved backside contact performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional backside contact formation processes are used, then substrate processing is performed, but alignment precision deteriorates due to substrate warpage and etching variations
Solution Approach 1:
The patent applies preliminary action by forming the placeholder structure before the actual backside contact structure. The placeholder structure is created in advance to define the precise location and dimensions of the contact hole, serving as a template that guides subsequent processing steps. This preliminary structure ensures alignment precision is maintained despite substrate warpage and etching variations that occur during later thermal and chemical processes.
Solution Approach 2:
The placeholder structure acts as an intermediary element between the source/drain region and the final backside contact structure. It mediates the alignment process by providing a stable reference structure that can be precisely formed and measured, then used to guide the formation of the actual contact. This intermediary structure transfers the alignment information through multiple processing steps without losing precision.
2Productivity
If contact poly pitch is reduced to increase device density, then device density improves, but alignment precision deteriorates due to substrate warpage and etching variation
Solution Approach 1:
By forming the placeholder structure in advance with precise dimensions and location, the patent enables reduced contact poly pitch while maintaining alignment precision. The placeholder structure serves as a pre-defined template that ensures each contact is accurately positioned even when pitch is reduced, compensating for substrate warpage and etching variations that become more significant at smaller dimensions.
Solution Approach 2:
The patent changes the parameter of contact structure formation by introducing a two-stage process: first forming a placeholder structure with controlled dimensions, then using it to define the final contact. This parameter change allows precise control of contact pitch and position, enabling higher device density while maintaining manufacturing precision despite process variations.
3Ease of manufacture
If etching is performed to form contact holes, then contact structures can be formed, but deposition quality deteriorates due to tapering or cone shape of holes
Solution Approach 1:
The placeholder structure is formed in advance with vertical sidewalls and precise dimensions. This preliminary structure defines the contact hole geometry before metal deposition, ensuring that the holes have uniform width and vertical profiles rather than tapering or cone shapes. The placeholder acts as a mold that guides the deposition process, guaranteeing high deposition quality and uniform metal filling.
Data Source
AI summary
Provided is a semiconductor device and a method of manufacturing the semiconductor device. The semiconductor device includes: a 1st source/drain region; a 2nd source/drain region; a channel structure connecting the 1st source/drain region to the 2nd source/drain region; a gate structure surrounding the channel structure; a backside contact structure, below the 1st source/drain region, connected to the 1st source/drain region; and a 1st backside spacer at a lateral side of the backside contact structure.