Inkjet Resist Deposition for Solar Cell Etching
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Solution Overview
Problem
The existing methods for manufacturing solar cells, particularly in creating electrical contact structures, face challenges with the need for improved etching and plating techniques as they often require multiple stages and can be stressful on thinner, more delicate silicon wafers, necessitating a more precise and stress-free method for creating finer details.
Innovation Solution
The process involves ink jet printing an alkali removable, water insoluble hot melt ink onto a silicon wafer to form a resist image, followed by etching or plating in an aqueous acid medium, and then removing the resist image with an aqueous alkali, utilizing a non-contact method that reduces stress on the substrate and allows for finer detail creation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If screen printing is used to apply resist, then good image definition and reliability are achieved, but the method is contact-based and may stress delicate substrates
Solution Approach 1:
The patent replaces the mechanical screen printing process with an inkjet printing system that deposits resist material in a non-contact manner. The inkjet print head deposits liquid or aerosol resist droplets onto the substrate through a printhead, eliminating the mechanical contact and stress associated with screen printing while maintaining precise pattern formation through digitally controlled droplet placement.
Solution Approach 2:
The inkjet printing system utilizes pneumatic and hydraulic mechanisms to propel and control the deposition of resist material. Liquid or aerosol resist is delivered through fluid delivery systems and deposited as controlled droplets onto the substrate, enabling contactless application with high precision through fluid dynamics control rather than mechanical contact.
2Productivity
If conventional etching and plating methods are used, then electrical contact structures are created, but multiple stages are required and the process is complex
Solution Approach 1:
The patent combines multiple separate process stages into a more integrated workflow. By using inkjet printing to apply resist with finer detail capability, the process enables more precise single-stage or reduced-stage etching and plating operations, eliminating the need for multiple sequential stages required by conventional methods and simplifying the overall manufacturing process.
Solution Approach 2:
The invention changes the key parameter of resist application from mechanical screen printing to inkjet deposition, enabling finer feature sizes and more precise patterns. This parameter change in resist application capability directly enables simplified etching and plating processes with fewer stages, as the precise resist patterns allow for more efficient single-stage processing compared to conventional multi-stage approaches.
3Productivity
If thinner silicon wafers are used, then device performance is improved, but the substrates become more delicate and stress from conventional methods causes damage
Solution Approach 1:
The patent replaces mechanical screen printing with non-contact inkjet printing, eliminating the physical stress and potential damage to thin, delicate silicon wafers. The inkjet system deposits resist material through a printhead without mechanical contact, preserving substrate integrity while enabling precise pattern formation on fragile, high-performance thin wafers.
Solution Approach 2:
The inkjet-deposited resist acts as an intermediary that protects specific areas of the thin silicon wafer during subsequent etching and plating processes. The resist material is applied without stress and provides precise protective patterning, allowing thin wafers to undergo processing without direct mechanical or chemical stress to the substrate itself.
4Reliability
If screen printing is used, then reliable resist application is achieved, but finer detail and precision are limited
Solution Approach 1:
The patent replaces screen printing with inkjet printing technology that uses digitally controlled droplet deposition to achieve finer feature sizes and more precise patterns. The inkjet system can deposit resist material with sub-millimeter precision through computer-controlled printhead movement and droplet ejection timing, enabling detailed patterns that exceed the resolution limits of screen printing while maintaining process reliability through automated control.
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 provides improved resist image definition and reduces stress on the substrate, enabling the creation of finer electrical contact structures on thinner silicon wafers while ensuring effective removal of the resist without leaving residues, thus enhancing the efficiency and quality of solar cell manufacturing.
Implementation Method 1
ink jet printing an alkali removable water insoluble hot melt ink jet ink onto a substrate comprising a silicon wafer to form a resist image on the substrate
Implementation Method 2
removing the resist image with an aqueous alkali
Data Source
AI summary
A process of manufacturing a solar cell is provided. The process comprising the steps of: i) ink jet printing an alkali removable water insoluble hot melt ink jet ink onto a substrate comprising a silicon wafer to form a resist image on the substrate; ii) etching or plating the substrate in an aqueous acid medium; and iv) removing the resist image with an aqueous alkali.