Semiconductor Substrate Inspection Pads for Contact Failure Detection
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Solution Overview
Problem
It is challenging to determine whether defects in semiconductor substrates during electrical inspection are due to internal issues or contact failures with inspection needles, as high surface hardness electrode pads often prevent needle marks from forming, making it difficult to assess contact failures.
Innovation Solution
Incorporating second pads with lower surface hardness than the primary pads, which are not electrically connected to the internal circuit, to facilitate the formation of needle marks during inspection, allowing for easier determination of contact failures between inspection needles and the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the surface hardness of electrode pads is increased to prevent needle marks, then the pads resist needle indentation, but it becomes difficult to determine whether defects are caused by contact failures or internal substrate issues
Solution Approach 1:
The pad structure is segmented into two distinct types: first pads with high surface hardness for electrical connection, and second pads with low surface hardness for inspection marking. This segmentation allows each pad type to fulfill its specific function without compromising the other.
Solution Approach 2:
Different regions of the pad structure are assigned different hardness properties. The first pads maintain high hardness locally to prevent unwanted marks, while the second pads have low hardness locally to facilitate visible needle marks for defect analysis.
2Object-generated harmful factors
If the surface hardness of electrode pads is increased to prevent needle marks, then needle marks are prevented on the pad, but contact failure detection capability is reduced
Solution Approach 1:
The second pads with low hardness serve as intermediary elements that provide visible marking capability. These intermediary pads allow inspection needles to leave marks that indicate successful contact, thereby mediating between the need for mark prevention on functional pads and the need for contact verification.
Solution Approach 2:
The second pads are designed as sacrificial or disposable elements whose primary purpose is to receive needle marks during inspection. They serve their function of indicating contact success and can be replaced or re-inspected without affecting the permanent functional first pads.
Data Source
AI summary
A semiconductor substrate has an internal circuit, a plurality of first pads electrically connected to the internal circuit, and one or a plurality of second pads that have a surface hardness lower than that of the plurality of first pads and are not electrically connected to the internal circuit.