Contact Hole Step Portion for Semiconductor Electrode Stability
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Solution Overview
Problem
Conventional thin film transistors face challenges in forming contact holes with precise control over etching, leading to issues like partial thinning or disconnection of wiring, especially when the semiconductor layer is thin, and require complex multi-step processes increasing manufacturing costs.
Innovation Solution
A method involving the use of a resist with a step portion as a mask to form a contact hole with a step portion at the side surface, allowing for a single etching process that covers the side surface of the contact hole with a conductive layer, reducing the number of masks and manufacturing steps while preventing variations in electrode thickness or disconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a contact hole is formed into a tapered shape to allow wiring material to cover the side surface, then the wiring coverage is improved, but the upper portion of the contact hole is widened making minute contact holes difficult to form
Solution Approach 1:
A step portion is formed in the insulating layer before contact hole formation. This preliminary structural preparation allows the contact hole to maintain a smaller upper opening while still enabling wiring material to cover the side surface effectively, resolving the contradiction between wiring coverage and contact hole size control
2Manufacturing precision
If two etching processes are used to form a contact hole with a step portion, then the wiring coverage is improved, but the number of masks and manufacturing steps are increased
Solution Approach 1:
The step portion formation and contact hole formation are merged into a single etching process. By using a resist mask with a specific pattern, both the step portion in the insulating layer and the contact hole through-hole are created simultaneously, eliminating the need for separate etching processes and reducing manufacturing complexity
3Reliability
If the contact hole is formed to reach the surface of the source region or drain region, then the electrical connection is improved, but the etching control becomes difficult especially when the semiconductor layer is thin
Solution Approach 1:
The step portion is formed in the insulating layer before contact hole etching. This preliminary structure acts as a guide and stop layer during etching, allowing precise control of the etching depth and shape while ensuring the contact hole reaches the semiconductor layer without excessive etching into the source or drain regions
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 the easy manufacture of semiconductor devices with stable source and drain electrodes, reducing the risk of electrode variation and disconnection, and simplifies the manufacturing process by eliminating the need for complex multi-step etching processes.
Implementation Method 1
a contact hole having a step portion at the side surface is formed using a resist having a step portion at the side surface as a mask
Implementation Method 2
a conductive layer is formed in the contact hole... covering the side surface of an opening which reaches the semiconductor layer
Data Source
AI summary
A method for easily manufacturing a semiconductor device in which variation in thickness or disconnection of a source electrode or a drain electrode is prevented is proposed. A semiconductor device includes a semiconductor layer formed over an insulating substrate; a first insulating layer formed over the semiconductor layer; a gate electrode formed over the first insulating layer; a second insulating layer formed over the gate electrode; an opening which reaches the semiconductor layer and is formed at least in the first insulating layer and the second insulating layer; and a step portion formed at a side surface of the second insulating layer in the opening.