Unleveled Gate Structure for Semiconductor Miniaturization
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Solution Overview
Problem
Existing semiconductor manufacturing processes are inadequate for effective miniaturization, leading to challenges in device scaling-down due to issues with tolerances and the risk of short circuits and breakdown voltage in semiconductor structures.
Innovation Solution
The method involves forming a semiconductor structure with a gate dielectric layer, a work function metal layer, and a gate electrode layer, where the top surfaces are not level, and using etching processes to create recesses between these layers to form a hard mask structure with different thicknesses, which helps control distances and prevent short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If device dimensions are shrunk to increase integration levels, then circuit integration density is improved, but manufacturing precision and tolerance control deteriorate
Solution Approach 1:
The gate structure is segmented into multiple layers (gate dielectric layer, work function metal layer, gate electrode layer) with non-uniform thicknesses. This segmentation allows each layer to be independently controlled and optimized, enabling precise dimensional control even as overall device dimensions are shrunk for higher integration density.
Solution Approach 2:
Different regions of the gate structure have different thicknesses tailored to local requirements. The gate electrode layer has varying thickness to provide appropriate electrical characteristics in different areas, while the work function metal layer has non-uniform thickness to maintain proper work function values. This local quality approach enables precise control of electrical properties without requiring uniform dimensional tolerances across the entire structure.
2Length of moving object
If layer thicknesses are reduced for miniaturization, then device size is improved, but reliability against short circuits and breakdown voltage degradation worsens
Solution Approach 1:
The gate structure employs a nested multi-layer configuration where the gate dielectric layer, work function metal layer, and gate electrode layer are stacked together. This nesting allows each layer to contribute to both miniaturization and reliability: thinner individual layers enable smaller device size, while the combined structure maintains adequate breakdown voltage and prevents short circuits through proper material selection and thickness distribution.
Solution Approach 2:
The gate structure uses composite materials comprising different functional layers (dielectric, metal, electrode materials) with distinct properties. This composite approach allows optimization of each material for its specific function while maintaining overall reliability: the dielectric layer provides insulation, the work function metal layer controls electrical characteristics, and the gate electrode layer provides conductivity, all while enabling reduced device dimensions.
Data Source
AI summary
Methods for forming the semiconductor structure are provided. The method includes forming a fin structure and forming a gate dielectric layer across the fin structure. The method includes forming a work function metal layer over the gate dielectric layer and forming a gate electrode layer over the work function metal layer. The method further includes etching the work function metal layer to form a gap and etching the gate dielectric layer to enlarge the gap. The method further includes etching the gate electrode layer from the enlarged gap and forming a dielectric layer covering the gate dielectric layer, the work function metal layer, and the gate electrode layer. In addition, the dielectric layer includes a first portion, a second portion, and a third portion, and the first portion is thicker than the second portion, and the second portion is thicker than the third portion.