Semiconductor Contact Hole Formation via Segmented Etching
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Solution Overview
Problem
The existing technologies face challenges in accurately forming contact holes for semiconductor devices, particularly due to the need for multiple etching steps and the use of sacrificial layers, which increases production costs and complexity.
Innovation Solution
The semiconductor device architecture includes a layered structure with specific insulation and metal films, allowing for the formation of contact holes with precise depth and reduced etching complexity, eliminating the need for sacrificial layers and minimizing the number of metal films used.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sacrificial layer is used to prevent hydrofluoric acid permeation during cleaning, then the oxide semiconductor is protected from damage, but the manufacturing process becomes more complex and costly due to multiple etching steps
Solution Approach 1:
The patent removes the sacrificial layer (oxide film) entirely from the structure. Instead of using aluminum oxide as a protective sacrificial layer that requires multiple etching steps, the invention forms contact holes through insulation films using a simplified process that does not require this intermediate protective layer, thereby reducing manufacturing complexity while maintaining protection of the oxide semiconductor
Solution Approach 2:
The patent segments the etching process into separate steps for different contact holes. First contact holes are formed through the first insulation film to connect to the oxide semiconductor, and second contact holes are formed through the second insulation film to connect to the LTPS transistor. This segmentation allows each etching step to be optimized independently, eliminating the need for a sacrificial layer that would require coordinated etching of multiple layers simultaneously
2Productivity
If through holes are formed collectively for both first TFT and second TFT, then the number of etching steps is reduced, but the etching accuracy deteriorates because different numbers of insulation films must be etched for each TFT type
Solution Approach 1:
The patent divides the contact hole formation into two separate etching processes: first etching forms contact holes through the first insulation film for the oxide semiconductor TFT, and second etching forms contact holes through the second insulation film for the LTPS TFT. This segmentation allows each etching step to achieve the precise depth required for its specific application, solving the accuracy problem while maintaining efficient productivity
3Ease of manufacture
If the sacrificial layer is etched twice to form contact holes, then both first TFT and second TFT connections are achieved, but the production cost increases
Solution Approach 1:
The patent eliminates the sacrificial layer entirely from the manufacturing process. By removing the aluminum oxide sacrificial layer that would require twice etching, the invention simplifies the process to form contact holes directly through the necessary insulation films, thereby reducing production costs while maintaining the capability to form both first and second TFT connections
Data Source
AI summary
A semiconductor device includes a first TFT, a first source-side connection section that is formed from a part of a second metal film and connected to a first source region, a first drain-side connection section that is formed from a part of the second metal film and connected to a first drain region, a second TFT that is driven by the first TFT, a second source-side connection section that is formed from a part of a first metal film and connected to a second source region, and a second drain-side connection section that is formed from a part of the first metal film or a second transparent electrode film and connected to a second drain region.