Inner Spacer Gate Structure for Self-Aligned Gate Metal
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Solution Overview
Problem
Existing semiconductor devices face challenges in achieving precise alignment of gate metal to the edges of the gate structure without causing stress or shorts, which complicates fabrication and increases costs.
Innovation Solution
A self-aligned inner spacer gate structure is employed, utilizing inner dielectric spacers to precisely align the gate metal to the p-GaN gate structure, eliminating the need for isotropic etch-back processes and reducing fabrication time and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional gate metal alignment methods are used, then gate metal can be connected to gate structure, but alignment precision is insufficient and stress/shorts may occur
Solution Approach 1:
Inner dielectric spacers are introduced as intermediary structures between the gate metal and gate structure. These spacers serve as physical mediators that precisely define the lateral position of gate metal, ensuring accurate alignment while preventing direct contact that could cause shorts or stress. The spacers act as self-aligned reference structures that eliminate alignment errors.
Solution Approach 2:
The inner dielectric spacers are formed through self-aligned processes where the spacer material automatically conforms to the gate structure geometry. This self-alignment mechanism ensures that the gate metal, deposited subsequent to spacer formation, is precisely positioned relative to the gate structure without requiring additional alignment steps, thereby achieving high manufacturing precision and reliability.
2Manufacturing precision
If isotropic etch-back processes are used for alignment, then gate metal alignment can be achieved, but fabrication complexity and costs increase
Solution Approach 1:
The complex isotropic etch-back alignment process is extracted and replaced by a simpler spacer-based self-aligned approach. The inner dielectric spacers are formed using standard deposition and patterning techniques, eliminating the need for complex etch-back processes while maintaining or improving alignment precision. This reduces fabrication process complexity and costs.
Solution Approach 2:
The self-aligned spacer formation process automatically provides precise alignment without requiring complex etch-back operations. The spacer material self-conforms to the gate structure, and subsequent gate metal deposition naturally aligns to the spacer-defined position, simplifying the overall fabrication process while maintaining high alignment precision.
3Productivity
If inner dielectric spacers are used for self-aligned gate metal, then fabrication time and costs are reduced, but alignment precision may be compromised
Solution Approach 1:
Inner dielectric spacers serve as precise intermediary reference structures that define the lateral position of gate metal. The spacers are formed with controlled thickness and sidewall profiles through standard deposition processes, providing accurate alignment references that maintain high manufacturing precision while enabling simplified fabrication procedures and improved productivity.
Solution Approach 2:
The self-aligned spacer formation process inherently provides precise alignment through the physical conformal deposition of spacer material on the gate structure. This self-service mechanism ensures that gate metal alignment precision is maintained without requiring complex additional steps, thereby achieving both high precision and improved fabrication efficiency.
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to a device with a self-aligned inner spacer sidewall structures. The structure includes: a gate structure on a semiconductor substrate; a gate metal connecting to the gate structure and offset from edges of the gate structure; and inner sidewall spacers on an upper surface of the gate structure and surrounding the gate metal.