Self-Aligned Inner Spacer Gate Structure for Precise HEMT Alignment
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Solution Overview
Problem
Existing semiconductor fabrication processes for high-electron-mobility transistors (HEMTs) face challenges in aligning gate metal to the edges of the gate structure, leading to increased fabrication time and costs, and potential stress or shorts, which affect device performance.
Innovation Solution
A self-aligned inner spacer gate structure is introduced, where the gate metal is precisely aligned using inner dielectric spacers, eliminating the need for isotropic etch-back processes and ensuring accurate alignment without causing stress or shorts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional gate metal alignment processes are used, then gate metal can be connected to gate structure, but alignment precision is poor and fabrication time increases
Solution Approach 1:
The patent introduces inner spacer sidewall structures as intermediary elements between the gate metal and gate structure. These spacers serve as self-aligned reference structures that guide precise gate metal deposition, eliminating the need for complex alignment processes while maintaining high precision. The spacers act as a mediator that translates the gate structure geometry into precise gate metal positioning.
Solution Approach 2:
The inner spacer sidewall structures are formed before gate metal deposition through a self-aligned process. This preliminary formation of spacers establishes the precise alignment reference in advance, allowing gate metal to be deposited accurately without requiring subsequent alignment adjustments or additional etch-back processes.
2Reliability
If traditional alignment processes are used, then gate metal can be formed, but stress and shorts may occur affecting device performance
Solution Approach 1:
The inner spacer sidewall structures serve as intermediary elements that physically separate and electrically isolate the gate metal from the gate structure edges. This mediation prevents direct contact that could cause shorts, while the controlled spacing eliminates stress concentration points, thereby improving device reliability without compromising electrical performance.
Solution Approach 2:
The patent extracts the alignment reference function from the gate structure itself and separates it into dedicated inner spacer sidewall structures. This extraction allows the gate structure to focus on its primary function while the spacers handle alignment and isolation, preventing stress and short issues that arise when these functions are combined.
3Manufacturing 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 inner spacer sidewall structures are formed through a self-aligned process where the spacers automatically position themselves relative to the gate structure without requiring additional alignment steps. The spacers serve themselves as the alignment reference, eliminating the need for complex isotropic etch-back processes and reducing fabrication complexity while maintaining high precision.
Solution Approach 2:
The self-aligned inner spacer structures are formed preliminarily before gate metal deposition, establishing the alignment reference in advance. This preliminary action eliminates the need for subsequent isotropic etch-back processes, simplifying the overall fabrication workflow while achieving precise gate metal alignment.
Data Source
Figure 1
Figure 2A~2C
Figure 2D~2E
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.