Semiconductor Wafer Back Electrode Process to Prevent Silver Oxidation
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Solution Overview
Problem
The use of silver as a back surface electrode in semiconductor chips is prone to oxidation, which can degrade the performance and reliability of semiconductor devices, and existing methods do not effectively prevent this oxidation.
Innovation Solution
A manufacturing method involving selective grinding of the semiconductor wafer to create a central portion with reduced thickness and a peripheral portion with increased thickness, followed by the application of a silver film as the back surface electrode and adherence to a dicing tape with a polyvinyl chloride base material layer to prevent oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a silver film is used as the back surface electrode instead of a gold film, then the manufacturing cost is reduced, but the oxidation resistance deteriorates
Solution Approach 1:
The invention uses a composite structure where a silver film (cost-effective) is combined with a protective film made of oxidation-resistant material. This composite approach allows the silver film to provide electrical conductivity and cost benefits while the protective film layer prevents oxidation, thus resolving the contradiction between cost reduction and oxidation resistance.
2Ease of manufacture
If the back surface of the semiconductor wafer is polished to create a thickness difference between central and peripheral portions, then the dicing process is improved, but the manufacturing complexity increases
Solution Approach 1:
The invention performs preliminary grinding of the back surface to create a thickness difference between the central and peripheral portions before the dicing process. This preliminary action facilitates easier dicing by preventing chip breakage and improving handling, while the added complexity is minimal and integrated into the existing manufacturing flow.
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 method effectively prevents oxidation of the silver back surface electrode, maintaining device performance and reliability while reducing manufacturing costs by using silver instead of gold.
Implementation Method 1
as silver is more easily oxidized compared to gold. And, when the silver film is oxidized, there is a possibility that the performance and reliability of a semiconductor device assembled by using the semiconductor chip may be decreased. Therefore, it is desirable to take some measures to prevent the oxidation of the back surface electrode
Data Source
AI summary
After grinding a back surface of a semiconductor substrate SB such that a thickness of a central portion of the semiconductor substrate is less than a thickness of a peripheral portion of the semiconductor substrate, a metal film including a film made of silver or copper is formed on the back surface of the semiconductor substrate. Thereafter, a dicing tape is adhered to the back surface of the semiconductor substrate via the metal film. A base material layer of the dicing tape is made of polyvinyl chloride. Also, after separating the peripheral portion from the central portion and the dicing tape, the semiconductor substrate adhered to the dicing tape is diced. Thereafter, the semiconductor substrate adhered to the dicing tape is transported.