Silicon Wafer Etching via Segmented Top and Bottom Application
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Solution Overview
Problem
Existing methods for treating silicon wafers, such as etching away material from both sides using etching solutions, fail to efficiently address sawing damage and achieve optimal texturing and polish-etching results, particularly in producing a smooth and reflective underside for solar cells.
Innovation Solution
A method and device where silicon wafers are transported horizontally, with texturing etching solution applied from above and polish-etching solution applied exclusively from below, utilizing nozzles and transport rollers to control the etching process, allowing for precise material removal and surface preparation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If etching solution is applied from both sides of silicon wafers, then sawing damage is eliminated, but texturing control and material removal precision deteriorate
Solution Approach 1:
The etching process is segmented into two distinct stages: first applying etching solution only from the top side to remove sawing damage and create texturing, then flipping the wafer to apply solution from the bottom side for polish-etching. This segmentation allows independent optimization of each etching objective without interference from bidirectional solution application.
Solution Approach 2:
The conventional approach of simultaneous bidirectional etching is inverted by sequentially applying etching solution from opposite sides. The wafer is flipped between etching stages, reversing the application direction to achieve different surface treatment objectives at different times, thereby improving both damage removal and texturing control.
2Productivity
If etching solution is sprayed from above during transport, then texturing efficiency is improved, but solution application to the underside becomes uncontrolled
Solution Approach 1:
The etching process is segmented into two distinct stages: first applying etching solution only from the top side to remove sawing damage and create texturing, then flipping the wafer to apply solution from the bottom side for polish-etching. This segmentation allows independent optimization of each etching objective without interference from bidirectional solution application.
Solution Approach 2:
The top-side etching and texturing is performed as a preliminary action before the wafer is flipped for bottom-side treatment. By completing the texturing phase first with controlled top-side solution application, the subsequent flip ensures that only minimal solution transfer to the underside occurs during the second etching stage, preventing excessive texturing on the back surface.
3Reliability
If material removal of 4-6 μm from top and 2 μm from bottom is achieved, then sawing damage is eliminated, but etching solution consumption increases
Solution Approach 1:
The etching solution application is localized to specific regions and orientations. During the first stage, solution is applied only from the top side to the texturing surface. During the second stage, solution is applied only from the bottom side to the polish-etch surface. This localized application eliminates unnecessary solution exposure and transfer, reducing overall consumption while achieving the required 4-6 μm top and 2 μm bottom material removal for complete sawing damage elimination.
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 effectively removes 4-6 μm of material from the top side and 2 μm from the underside, eliminating sawing damage while achieving desired texturing and polish-etching, resulting in improved solar cell performance with efficient material usage and minimal surface texturing.
Implementation Method 1
texturing etching solution for texturing the silicon wafers is applied or sprayed on from above during transport by means of nozzles or the like
Implementation Method 2
The device also has a horizontal transport path with tranport rollers or the like
Implementation Method 3
the silicon wafers, with the same orientation as in the first method step, are wetted with a polish etching solution for polish-etching from below
Data Source
AI summary
A method and device for treating silicon wafers. In a first step, the silicon wafers (22) are conveyed flat along a continuous, horizontal conveyor belt (12, 32) and nozzles (20) or the like spray an etching solution (21) from the top onto the wafers to texture them, only little etching solution (21) being applied to the silicon wafers (22) from below. In a second step, the silicon wafers (22), which are aligned as in the first step, are wetted exclusively from below with the etching solution (35) to etch-polish them.