Semiconductor Gate Structure with Non-Uniform Profile
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Solution Overview
Problem
Existing 'gate last' processes for forming metal gates in semiconductor devices are not entirely satisfactory as device scaling-down continues, particularly in terms of electrical performance and adhesion between the metal gate and sidewalls.
Innovation Solution
A semiconductor structure is formed with a dummy gate structure having a designed profile, where the dummy gate is replaced by a metal gate, with specific etching processes controlling the profile to improve electrical performance and adhesion, including the use of high-k dielectric materials and work function metals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional gate last process is used to form metal gates, then the number of subsequent processes is reduced, but the electrical performance and adhesion of the metal gate structure deteriorate
Solution Approach 1:
The dummy gate structure is formed in advance with a specifically designed profile (wider at the middle portion than at the top and bottom portions) before the metal gate formation process. This preliminary structuring of the dummy gate enables improved adhesion and electrical performance in the final metal gate structure without requiring additional post-processing steps, thus maintaining the efficiency of the gate-last approach while achieving better reliability
Solution Approach 2:
The invention changes the geometric parameters of the dummy gate structure by creating a non-uniform profile where the middle portion width is greater than the top and bottom portions. This parameter modification of the dummy gate geometry directly influences the metal gate formation process, resulting in improved adhesion and electrical characteristics without adding process complexity
2Productivity
If device feature sizes are shrunk to increase integration levels, then the higher levels of integration are achieved, but the tolerances and manufacturing precision become more difficult to maintain
Solution Approach 1:
The dummy gate structure is designed with non-uniform local dimensions, where the middle portion has a different width than the top and bottom portions. This local variation in geometry provides better control over the metal gate formation process at scaled dimensions, enabling improved manufacturing precision and tolerance control in miniaturized devices while maintaining high integration levels
Data Source
AI summary
Semiconductor structures are provided. The semiconductor structure includes a substrate and a gate structure formed over the substrate. In addition, a sidewall of the gate structure has a top portion having a first inclination, a middle portion having a second inclination, and a bottom portion having a third inclination, and the first inclination, the second inclination, and the third inclination are different from one another.