Wafer Reflow Oxide Removal Using Electron Attachment Heating
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Solution Overview
Problem
Existing wafer bumping processes require organic fluxes for oxide removal during reflow, which is not environmentally friendly and can be inefficient.
Innovation Solution
A batch fluxless process using an apparatus with a heating plate and electron attachment pin plate for oxide removal and reflow treatment, enabling rapid heating and cooling of wafers up to 304.8 mm in size, utilizing electron attachment to reduce oxides and produce hydrogen anions for oxide removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic fluxes are used for oxide removal during reflow, then good wetting of molten solder is achieved, but environmental pollution and process inefficiency occur
Solution Approach 1:
The patent removes organic fluxes from the reflow process entirely and replaces them with electron attachment for oxide removal. The electron attachment unit generates electrons that attach to oxide molecules on the wafer surface, converting them to negative ions that are then removed by gas flow, eliminating the need for harmful organic chemicals while maintaining effective oxide removal.
Solution Approach 2:
The patent replaces the chemical mechanism (organic fluxes) with a physical mechanism (electron attachment). Electrons are generated and directed at the wafer surface to attach to oxide molecules, a physical process that substitutes the chemical action of organic fluxes, thereby eliminating environmental pollution while achieving oxide removal.
2Productivity
If batch processing is used for wafer reflow, then processing time is reduced, but heating and cooling control becomes more difficult
Solution Approach 1:
The patent segments the heating and cooling functions into separate, independently controlled units. The heating plate can be raised to contact the sample plate for heating, then lowered to allow passive cooling. This segmentation enables rapid temperature changes while maintaining precise control over the thermal history of the wafers during batch processing.
Solution Approach 2:
The heating plate is designed with dynamic movement capability, allowing it to be raised and lowered relative to the sample plate. This dynamic positioning enables control over the degree and duration of thermal contact, providing flexible temperature control for batch processing while maintaining rapid heating and cooling rates.
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
The process achieves efficient oxide removal and reflow treatment within one hour, is environmentally friendly, and suitable for small-scale batch processing, suitable for R&D purposes.
Implementation Method 1
utilizing electron attachment to reduce oxides and produce hydrogen anions for oxide removal
Implementation Method 2
heating the wafer sample on the sample plate when the heating plate is in contact with the sample plate
Implementation Method 3
The term 'reflow' refers to a process for making a previously applied solder on a substrate melt and flow upon application of an energy source such as, for example, thermal energy
Data Source
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AI summary
The present invention relates to an apparatus and method for wafer oxide removal and reflow treatment. In particular, the present invention relates to an apparatus for wafer oxide removal and reflow treatment, comprising: a heating plate (1), a sample plate (2) for supporting a wafer sample above the heating plate (1), and an electron attachment pin plate (3) above the sample plate (2), wherein the heating plate (1) is configured to be capable of moving up and down, and contacting and heating the sample plate (2).