Semiconductor Isolation Structure for Coplanar Multi-Voltage Regions
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Solution Overview
Problem
The development of semiconductor integrated circuits with varying threshold and operation voltages leads to height differences in manufacturing processes, causing yield issues due to differences in gate oxide layers and trench isolation structures.
Innovation Solution
A semiconductor structure with trench isolation and distinct gate oxide layers is fabricated, featuring a medium-voltage and low-voltage device region with coplanar trench surfaces and varying gate oxide thicknesses, along with a method that includes conformal mask deposition, resist patterning, and selective oxidation to form and remove sacrificial oxide layers, ensuring proper surface exposure and gate formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If different gate oxide layer thicknesses are used to achieve different operation voltages, then voltage control precision is improved, but height differences between regions are generated causing manufacturing problems
Solution Approach 1:
The substrate is divided into multiple device regions (first device region and second device region) with different gate oxide layer thicknesses. Each region can be independently optimized for specific voltage requirements, allowing precise voltage control while managing height differences through regional segmentation.
Solution Approach 2:
Different gate oxide layer thicknesses are applied to different device regions based on their specific voltage requirements. The first device region receives a first gate oxide layer thickness while the second device region receives a different thickness, enabling localized optimization of electrical characteristics without affecting the entire substrate uniformly.
2Adaptability or versatility
If height differences are created between high-voltage and low-voltage areas, then voltage control is improved, but manufacturing yield decreases due to process problems
Solution Approach 1:
The patent addresses height differences by introducing additional structural dimensions - specifically using trench isolation structures with carefully controlled depths and fill materials, as well as adjusting gate electrode structures. This multi-dimensional approach allows voltage control while compensating for height variations that would otherwise harm manufacturing yield.
3Reliability
If thicker gate oxide layers are used in high-voltage areas, then operation voltage is enhanced, but coplanarity with low-voltage areas deteriorates
Solution Approach 1:
The patent employs nested structural approaches where trench isolation structures are integrated within the substrate, and gate electrodes are positioned at different levels. The trench isolation structures with varying depths allow thicker gate oxide layers in high-voltage regions while maintaining overall surface coplanarity through the nesting of isolation structures and gate electrodes at different hierarchical levels.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances manufacturing yield by maintaining coplanar trench surfaces and appropriate gate oxide thicknesses, addressing the challenges of height differences and voltage variations in semiconductor devices.
Implementation Method 1
The top surface of the substrate in the first device region is oxidized to form a sacrificial oxide layer
Data Source
AI summary
A semiconductor structure includes a substrate having a first device region and a second device region in proximity to the first device region. A trench isolation structure is disposed in the substrate between the first device region and the second device region. The trench isolation structure includes a first bottom surface within the first device region and a second bottom surface within the second device region. The first bottom surface is coplanar with the second bottom surface.