Oxide Semiconductor Transistor Polishing Method
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Solution Overview
Problem
Miniaturization of transistors for semiconductor devices leads to decreased yield and compromised characteristics due to the need for precise alignment of oxide semiconductor and gate electrode layers, and chemical mechanical polishing treatments that damage the semiconductor layer.
Innovation Solution
A semiconductor device structure and manufacturing method where a conductive film forms source and drain electrode layers covering an oxide semiconductor layer and channel protection layer, with the overlapping region removed by chemical mechanical polishing, and sidewall layers are formed to create a Lov region without the need for precise etching, thereby protecting the oxide semiconductor layer and improving processing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemical mechanical polishing treatment is performed on the conductive film to remove overlapping regions, then manufacturing precision is improved, but the oxide semiconductor layer is damaged
Solution Approach 1:
A protective film is formed over the oxide semiconductor layer before the chemical mechanical polishing step. This protective film prevents damage to the oxide semiconductor layer during polishing while allowing the polishing process to proceed to achieve precise alignment of the conductive film with the oxide semiconductor layer.
Solution Approach 2:
The protective film acts as an intermediary layer between the polishing pad and the oxide semiconductor layer. It absorbs the mechanical stress and friction during polishing, preventing direct contact and damage to the oxide semiconductor layer while still allowing the conductive film to be polished to the required precision.
2Productivity
If transistor size is miniaturized to achieve high-speed operation and low power consumption, then productivity is improved, but manufacturing precision requirements increase leading to decreased yield
Solution Approach 1:
The protective film is formed in advance before the polishing step, enabling precise alignment to be achieved through polishing without the risk of damage. This preliminary protection allows manufacturers to pursue miniaturization with confidence that the precision requirements can be met without compromising yield.
Solution Approach 2:
The invention replaces the traditional etching process with chemical mechanical polishing to remove the conductive film in overlapping regions. Polishing provides more uniform and controllable material removal compared to etching, achieving better alignment precision with reduced sensitivity to process variations, which is critical for miniaturized transistors.
3Manufacturing precision
If etching step is used to remove conductive film overlapping region, then manufacturing precision is improved, but process complexity increases
Solution Approach 1:
The invention extracts and eliminates the etching step from the manufacturing process by using chemical mechanical polishing instead. This removes the need for resist mask formation and etching parameters optimization, simplifying the process while maintaining or improving alignment precision.
Solution Approach 2:
The invention changes the processing method from chemical/physical etching to mechanical-chemical polishing. This parameter change in the material removal mechanism simplifies the process flow by eliminating the need for photoresist application and etching, while providing better control over the removal depth and uniformity for precise alignment.
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 allows for the miniaturization of transistors with high electric characteristics and high yield, reducing on-state current decrease and maintaining favorable transistor characteristics by protecting the oxide semiconductor layer during polishing and enabling precise processing without etching steps.
Implementation Method 1
a region of the conductive film which overlaps with the oxide semiconductor layer and the channel protection layer is removed by chemical mechanical polishing treatment
Data Source
AI summary
To provide a miniaturized transistor having high electric characteristics. A conductive film to be a source electrode layer and a drain electrode layer is formed to cover an oxide semiconductor layer and a channel protection layer, and then a region of the conductive film, which overlaps with the oxide semiconductor layer and the channel protection layer, is removed by chemical mechanical polishing treatment. Precise processing can be performed accurately because an etching step using a resist mask is not performed in the step of removing part of the conductive film to be the source electrode layer and the drain electrode layer. With the channel protection layer, damage to the oxide semiconductor layer or a reduction in film thickness due to the chemical mechanical polishing treatment on the conductive film can be suppressed.