Polysilicon Resistor Tank Structure for Semiconductor Fabrication
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Solution Overview
Problem
Conventional methods for integrating metal gate transistors with polysilicon resistors face issues such as lateral over-etching and conductive residue due to height differences in hard masks, which affect the integrity and performance of semiconductor devices.
Innovation Solution
The method involves forming a tank in the shallow trench isolation (STI) of the resistor region and implanting boron atoms into the polysilicon layer to create differential etching selectivity, ensuring the polysilicon resistor and metal gate are even and reducing over-etching and residue issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to integrate metal gate transistor with polysilicon resistor, then the fabrication process is simple, but lateral over-etching and conductive residue occur due to height differences in hard masks
Solution Approach 1:
The patent introduces a vertical dimension solution by forming a tank structure (a recess or cavity) in the STI layer. This dimensional change allows the polysilicon resistor to be formed at a different height level, specifically within the tank region, thereby compensating for the height difference between the metal gate transistor and polysilicon resistor hard masks. This resolves the lateral over-etching issue by providing a structural foundation that equalizes the etching reference planes.
Solution Approach 2:
The patent applies local quality by creating a tank structure specifically in the STI layer at the resistor region, rather than uniformly modifying the entire structure. This localized modification allows the polysilicon resistor to be formed with proper height alignment only where needed (in the tank region), while leaving other regions unchanged. The tank provides localized height compensation to prevent over-etching and residue formation at the resistor contacts.
2Reliability
If height differences in hard masks are not compensated, then the fabrication process is simple, but lateral over-etching and conductive residue occur
Solution Approach 1:
The tank structure introduces a vertical dimension solution by creating a recess in the STI layer. This allows the polysilicon resistor to be positioned at a different height level, specifically lower than the surrounding STI surface, thereby compensating for the height difference between the metal gate transistor and polysilicon resistor hard masks. This resolves the lateral over-etching issue by providing a structural foundation that equalizes the etching reference planes.
Solution Approach 2:
The patent applies local quality by creating a tank structure specifically in the STI layer at the resistor region, rather than uniformly modifying the entire structure. This localized modification allows the polysilicon resistor to be formed with proper height alignment only where needed (in the tank region), while leaving other regions unchanged. The tank provides localized height compensation to prevent over-etching and residue formation at the resistor contacts.
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 improves the integration of metal gate transistors and polysilicon resistors by eliminating lateral over-etching and conductive residue, enhancing the reliability and performance of semiconductor devices.
Implementation Method 1
implanting boron atoms into the polysilicon layer to create differential etching selectivity
Data Source
AI summary
A method for fabricating semiconductor device is disclosed. The method includes the steps of: providing a substrate having a transistor region and a resistor region; forming a shallow trench isolation (STI) on the resistor region of the substrate; forming a tank in the STI; and forming a resistor in the tank and on two sides of the top surface of the STI outside the tank.