Sacrificial Gate Layout for Uniform Multi-Gate HV Fabrication
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Solution Overview
Problem
The challenge in semiconductor device fabrication lies in the complexity and cost of transitioning from planar high voltage devices to multi-gate counterparts, particularly due to differences in gate length and density, leading to issues like uneven etching and dishing during CMP processes, which affect device performance and reliability.
Innovation Solution
A method is introduced to form semiconductor devices with distinct gate structure densities by using sacrificial gate stacks of varying lengths in core and high voltage areas, accompanied by tailored photoresist layer patterning to ensure uniform etching and removal, thereby facilitating the transition to multi-gate structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If planar high voltage devices are transitioned to multi-gate structures, then device performance is improved, but fabrication complexity and cost increase
Solution Approach 1:
The substrate is divided into distinct first device area and second device area, with different gate structure densities in each area. Core devices use standard gate structures while high voltage devices use extended gate structures, allowing independent optimization of each device type without affecting the other.
Solution Approach 2:
Different gate structure densities are implemented in different areas of the substrate. The first device area has a first gate structure density suitable for core devices, while the second device area has a second gate structure density suitable for high voltage devices, enabling localized optimization for specific device requirements.
2Productivity
If gate structure density is increased in high voltage areas, then device integration is improved, but uneven etching and dishing occur during CMP processes
Solution Approach 1:
The patent implements different gate structure densities in different areas: a first gate structure density in the first device area and a second gate structure density in the second device area. This local differentiation allows high integration density where needed while maintaining etching uniformity in other areas, resolving the contradiction between integration and manufacturing precision.
Solution Approach 2:
The substrate is segmented into distinct device areas with different gate densities. By separating high voltage devices into a dedicated second device area with its own gate structure density, the patent avoids the uneven etching and dishing problems that would occur if a uniform high density were applied across the entire substrate.
3Reliability
If gate structure density varies across device areas, then noise and errors are reduced, but fabrication process complexity increases
Solution Approach 1:
The patent applies different gate structure densities in different areas to reduce noise and errors in high voltage devices while maintaining standard performance in core devices. The fabrication process complexity is managed by using standard semiconductor manufacturing techniques applied to different areas, rather than requiring entirely new process steps.
Data Source
AI summary
Embodiments with present disclosure provide a method for fabricating a semiconductor device with long gate lengths. A patterned photoresist layer is formed over device areas with long gate lengths to enable process uniformity and improve device density.