Al Alloy Electrode Deposition for Early Wafer Defect Detection
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Solution Overview
Problem
Conventional semiconductor device manufacturing methods fail to detect defects larger than 0.5 μm during wafer processing, leading to non-conforming devices and material wastage, as defect inspection sensitivity decreases after Al alloy film formation and voids or defects in the base-substrate Al alloy film can cause Vth anomalies.
Innovation Solution
A method involving the formation of a thin first Al alloy film with crystal grain boundaries smaller than 0.2 μm, allowing for sensitive defect detection using dark field inspection before patterning, followed by a thicker second Al alloy film deposition to form the emitter electrode, enabling detection of defects greater than 0.5 μm and reducing the need for burn-in tests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thick Al alloy film is formed for the emitter electrode, then the electrode strength and conductivity are improved, but defect detection sensitivity decreases and Vth anomalies occur
Solution Approach 1:
The Al alloy film is divided into two separate films: a thin first Al alloy film (50-500 nm) for defect detection and a thick second Al alloy film for electrode functionality. This segmentation allows the thin film to enable sensitive defect detection while the thick film provides the required electrode strength and conductivity, resolving the contradiction between detection sensitivity and electrode performance.
2Ease of manufacture
If defect inspection is performed after Al alloy film formation, then manufacturing process is simplified, but defect detection sensitivity decreases leading to non-conforming devices
Solution Approach 1:
Defect inspection is performed preliminarily after forming only the thin first Al alloy film, before depositing the thick second Al alloy film. This preliminary inspection enables detection of defects larger than 0.5 μm with high sensitivity. By performing the inspection at this intermediate stage, the patent maintains manufacturing simplicity while achieving high defect detection accuracy, preventing Vth anomalies before they occur.
3Productivity
If conventional single-stage Al alloy film deposition is used, then manufacturing process is simple, but defects larger than 0.5 μm cannot be detected causing material wastage
Solution Approach 1:
The Al alloy film deposition is segmented into two stages with an intermediate inspection step. The thin first film enables defect detection, while the thick second film ensures electrode performance. This segmented approach maintains high manufacturing efficiency by performing inspection at the optimal intermediate stage, preventing defective chips from proceeding to costly post-dicing testing and reducing material wastage.
4Reliability
If burn-in tests are performed on all chips, then reliability is ensured, but time and resource consumption increases
Solution Approach 1:
Defect inspection is performed preliminarily during wafer processing after forming the thin first Al alloy film, identifying and isolating defective regions before dicing. This preliminary defect detection enables selective processing of only non-defective chips, eliminating the need for exhaustive burn-in testing of all chips. The result is maintained device reliability with significantly reduced testing time and resource consumption.
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 detection of defects that could cause Vth anomalies during wafer processing, preventing non-conforming devices and reducing material wastage by identifying and removing defective chips early in the process, thus optimizing semiconductor device manufacturing efficiency.
Implementation Method 1
detecting, using a dark field, a defect of a surface of the first Al alloy film
Implementation Method 2
forming a first Al alloy film in contact with the surface structure and covering an entire surface of the interlayer insulating film
Data Source
AI summary
A method of manufacturing a semiconductor device, including: forming a surface structure including a metal oxide semiconductor structure in a semiconductor substrate; forming an interlayer insulating film covering the surface structure; forming, in the interlayer insulating film, a contact hole to expose the surface structure; forming a first Al alloy film in contact with the surface structure and covering an entire surface of the interlayer insulating film, the first Al alloy film having a thickness of 0.05 μm to 0.5 μm; detecting, using a dark field, a defect of a surface of the first Al alloy film; forming a second Al alloy film covering the entire surface of the first Al alloy film; patterning the first and second Al alloy films; annealing the first and second Al alloy films; and dicing the semiconductor substrate into a plurality of chips, and picking, among the plurality of chips, chips free of the detected defect.