Semiconductor Channel Formation Before Isolation Structures
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Solution Overview
Problem
Current semiconductor manufacturing techniques result in uneven shallow trench isolation (STI) structures due to non-uniform exposure during etching processes, leading to 'divots' that can cause lithographic issues, gate encapsulation problems, and increased leakage currents.
Innovation Solution
Forming semiconductor channel region materials before isolation structures, specifically forming a semiconductor material on the substrate regions where transistors will be created, and then forming isolation structures around these materials, which helps in achieving uniform trench isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If STI structures are formed first using traditional photolithography and etching processes, then isolation structures are created to separate circuit elements, but uneven topography with divots is created in the STI structures due to non-uniform exposure during subsequent etching processes
Solution Approach 1:
The patent applies preliminary action by forming the semiconductor channel region material before forming the isolation structures. This allows the channel material to be present during the trench formation process, enabling it to protect the underlying substrate and prevent divot formation during subsequent etching operations. The channel material acts as a sacrificial layer that maintains STI uniformity while still allowing isolation functionality.
Solution Approach 2:
The patent applies preliminary anti-action by using the semiconductor channel region material to counteract the harmful effect of non-uniform etching on the STI structures. The channel material is formed in advance to compensate for material removal during etching processes, preventing the formation of divots and maintaining a planar STI topography.
2Productivity
If traditional etching processes are used after STI formation, then circuit elements are processed, but divots are created that can cause incomplete etching and short circuits
Solution Approach 1:
The patent applies preliminary action by forming the semiconductor channel region material before isolation structure formation. This preliminary material presence protects the substrate during subsequent etching processes, preventing divot formation that would lead to incomplete etching and short circuits, thereby reducing device failure rates while maintaining processing capability.
3Ease of manufacture
If multiple etching and cleaning processes are performed after STI formation, then circuit elements are fabricated, but STI structures are consumed unevenly leading to topography issues
Solution Approach 1:
The patent applies preliminary action by forming the semiconductor channel region material before isolation structure formation. This allows multiple subsequent etching and cleaning processes to be performed with greater fabrication flexibility, as the channel material protects the substrate and maintains STI topography uniformity throughout the fabrication sequence.
Solution Approach 2:
The patent applies homogeneity by ensuring uniform STI structure formation through the presence of semiconductor channel region material during trench formation. This material ensures consistent protection and material removal rates across the STI structure, maintaining homogeneous topography even after multiple processing steps.
Data Source
AI summary
One example of a method disclosed herein for forming a transistor surrounded by an isolation structure includes the steps of, prior to forming the isolation structure, forming a semiconductor material on a region of a semiconducting substrate, after forming the semiconductor material, forming the isolation structure in the substrate around the semiconductor material, and forming a gate structure above the semiconductor material.