Cold Sprayed CIG Sputtering Target Manufacturing
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Solution Overview
Problem
Sputtering targets made from copper indium gallium (CIG) alloys face challenges such as porosity, structural defects, and macroscopic segregation due to large freezing ranges and thermal contraction, which affect the uniformity and efficiency of thin film deposition in solar cell production.
Innovation Solution
A cold spraying method is used to form CIG sputtering targets directly onto a backing structure, employing a powder with specific composition and particle size, and a high-velocity gas stream to achieve dense, uniform deposition with controlled porosity and minimal segregation, using a system with a converging-diverging nozzle and pre-chamber for optimal process gas heating and powder feeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sputtering target manufacturing methods are used, then production efficiency may be maintained, but porosity and structural defects occur in the target material
Solution Approach 1:
The patent changes the fundamental manufacturing parameters by transitioning from conventional sintering methods to cold spraying deposition. This involves controlling particle velocity (100-500 m/s), gas pressure (1-20 bar), and substrate temperature (room temperature to 200°C) to achieve dense target material with minimal porosity while maintaining high production efficiency through direct deposition onto backing structures
Solution Approach 2:
The patent replaces conventional mechanical sintering and bonding processes with a gas-dynamic cold spraying system. Powder particles are accelerated through a de Laval nozzle and deposited onto the backing structure through kinetic energy transfer, eliminating the need for high-temperature sintering and subsequent bonding operations
2Manufacturing precision
If cold spraying with fine powder particles is used, then deposition density improves, but deposition efficiency decreases
Solution Approach 1:
The patent optimizes powder particle size to the range of 1-10 μm, which balances deposition density and efficiency. This specific size range allows particles to achieve sufficient velocity for dense packing while maintaining adequate acceleration response to the gas stream, resulting in both high deposition density and acceptable deposition rates
Solution Approach 2:
The patent employs a de Laval nozzle design that dynamically accelerates the process gas and powder particles to supersonic velocities. The converging-diverging nozzle geometry creates a shock wave structure that efficiently transfers energy to the particles, ensuring fine particles reach the substrate with sufficient kinetic energy for dense deposition without requiring excessive gas pressure
3Stability of the object's composition
If macroscopic segregation is reduced through controlled cooling, then composition uniformity improves, but manufacturing complexity increases
Solution Approach 1:
The patent replaces conventional high-temperature melting and cooling processes with cold spraying deposition. Powder particles are deposited in the solid state onto the backing structure, eliminating macroscopic segregation entirely since there is no melting and solidification cycle. This approach achieves composition uniformity without requiring complex thermal management systems
Solution Approach 2:
The patent changes the deposition temperature parameter from high-temperature melting (above 1000°C for CIG materials) to room temperature or mildly elevated temperatures (up to 200°C). This parameter change prevents phase separation and macroscopic segregation during deposition, achieving uniform composition through direct solid-state accumulation rather than melting and controlled cooling
Data Source
AI summary
A method of making a sputtering target includes providing a backing structure, and forming a copper indium gallium sputtering target material on the backing structure by cold spraying. The step of cold spraying includes spraying a powder comprising copper, indium and gallium in a process gas stream, and at least one of an average particle size of the powder is at least 35 μm, a velocity of the process gas stream is at least 150 m/s, or a process gas pressure is 20 bar or less.