Oxide Semiconductor Etching for Miniaturization and Indium Recovery
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Solution Overview
Problem
Current processing techniques for semiconductor devices using oxide semiconductors are inefficient, leading to high costs due to the wastage of rare metals like indium and lack of resource-saving measures, with wet etching being unsuitable for miniaturization and dry etching being time-consuming and variable.
Innovation Solution
A method involving dry etching using a gas mixture of chlorine and oxygen to process island-shaped oxide semiconductor layers, with a gate insulating layer of silicon oxide, and combining wet and dry etching to form recessed portions and source/drain electrodes, allowing for miniaturization and resource recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wet etching is used to process oxide semiconductor layers, then ease of operation is improved, but manufacturing precision deteriorates due to isotropic etching preventing miniaturization
Solution Approach 1:
The patent segments the etching process into two distinct stages: first using wet etching to form the island-shaped oxide semiconductor layer with good ease of operation, then using dry etching to process the conductive layer and create recessed portions for miniaturization. This segmentation allows each method to be used for its optimal function.
Solution Approach 2:
The patent dynamically selects different etching methods based on the specific processing requirements at each stage. Wet etching is used when ease of operation is prioritized (forming island shapes), while dry etching is used when manufacturing precision and miniaturization are prioritized (processing conductive layers and creating recesses).
2Manufacturing precision
If dry etching is used to process oxide semiconductor layers, then manufacturing precision is improved for miniaturization, but productivity deteriorates due to small etching rates requiring much time
Solution Approach 1:
The patent segments the etching tasks so that wet etching handles the initial oxide semiconductor layer formation (where speed is less critical but ease of operation matters), while dry etching handles the subsequent conductive layer processing and recess creation (where precision is critical). This avoids using slow dry etching for all steps.
Solution Approach 2:
The patent applies partial dry etching to remove only the necessary portions of the oxide semiconductor layer to create recessed portions, rather than attempting to process the entire layer with dry etching. This reduces the total etching time while maintaining the precision benefits where needed.
3Ease of manufacture
If conventional etching techniques are used, then ease of manufacture is improved, but loss of substance increases due to removal and wastage of expensive rare metals like indium
Solution Approach 1:
The patent converts the harmful effect of material wastage into a benefit by using selective dry etching to create recessed portions that remove only the minimum necessary oxide semiconductor material, thereby preserving expensive rare metals like indium while still achieving the desired device structure.
Solution Approach 2:
The patent implements a more precise etching approach that minimizes discarding of valuable oxide semiconductor material containing rare metals. By using controlled dry etching to create recessed portions rather than removing entire layers, the method recovers and retains expensive materials that would otherwise be wasted.
4Manufacturing precision
If dry etching is used to process conductive layers and oxide semiconductor layers, then manufacturing precision is improved for miniaturization, but loss of time increases due to variable etching rates and process complexity
Solution Approach 1:
The patent segments the processing into distinct etching stages: wet etching for oxide semiconductor layer formation, then dry etching for conductive layer processing. This segmentation allows optimization of each stage independently, reducing total process time while maintaining precision where critical.
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 enables miniaturization and performance improvement of semiconductor devices while reducing costs by efficiently using indium and other resources, and improving throughput through controlled etching processes.
Implementation Method 1
the island-shaped oxide semiconductor layer and the conductive layer covering the island-shaped oxide semiconductor layer are processed by dry etching using a gas including chlorine and oxygen
Implementation Method 2
the oxide semiconductor layer is processed by wet etching to form an island-shaped oxide semiconductor layer
Data Source
AI summary
An object is to establish a processing technique in manufacture of a semiconductor device in which an oxide semiconductor is used. A gate electrode is formed over a substrate, a gate insulating layer is formed over the gate electrode, an oxide semiconductor layer is formed over the gate insulating layer, the oxide semiconductor layer is processed by wet etching to form an island-shaped oxide semiconductor layer, a conductive layer is formed to cover the island-shaped oxide semiconductor layer, the conductive layer is processed by dry etching to form a source electrode, and a drain electrode and part of the island-shaped oxide semiconductor layer is removed by dry etching to form a recessed portion in the island-shaped oxide semiconductor layer.