Molybdenum Target Plasma Projection with Cryogenic Cooling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for producing molybdenum targets for vacuum deposition processes, such as plasma spray, fail to achieve properties similar to those obtained by traditional manufacturing processes, particularly in terms of purity, density, and electrical resistivity, which are crucial for applications like photovoltaic and thin-film transistor technologies.
Innovation Solution
A method involving plasma projection using a plasma torch with cryogenic cooling jets to project molybdenum powder in an inert gas atmosphere, reducing oxidation and improving target quality by ensuring immediate cooling and clean cohesion between particles, while also using a reducing plasma gas mixture to minimize oxide levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional plasma spray methods are used to produce molybdenum targets, then the production process is simple and fast, but the target quality (purity, density, electrical resistivity) does not reach the level of traditional manufacturing processes
Solution Approach 1:
The invention changes key process parameters including using cryogenic cooling jets to reduce target temperature, using a reducing plasma gas mixture (hydrogen-containing) to minimize oxide levels, and controlling powder projection parameters to achieve dense particle packing. These parameter changes transform the plasma spray process from a simple fast method into one that produces target quality comparable to traditional manufacturing.
Solution Approach 2:
The invention uses a reducing plasma gas mixture containing hydrogen to create a reducing atmosphere during projection. This atmosphere prevents oxidation of molybdenum powder particles and minimizes oxide levels in the final target, significantly improving target purity and quality without requiring complex post-processing.
2Reliability
If molybdenum powder is projected using plasma spray without cryogenic cooling, then the process is simpler, but oxidation occurs and particle cohesion is poor
Solution Approach 1:
The invention applies cryogenic cooling jets immediately during the powder projection process to prevent oxidation before it can occur. The cooling action is performed in advance and simultaneously with particle deposition, ensuring particles are cooled and protected from oxidation as they are being projected and bonded to the target surface.
Solution Approach 2:
The cryogenic cooling jets act as an intermediary between the hot plasma spray process and the molybdenum powder particles. The cooling gas mediates the thermal interaction, rapidly cooling particles to prevent oxidation while also enhancing particle cohesion through thermal contraction and improved bonding to the target surface.
3Manufacturing precision
If higher powder purity is used to reduce oxygen content in targets, then target quality improves, but material cost increases
Solution Approach 1:
The invention converts the potentially harmful oxidation effect into a beneficial process by using a reducing plasma atmosphere. Instead of trying to prevent oxidation through expensive high-purity powder, the process uses hydrogen-containing plasma to actively reduce oxides during projection, transforming oxygen that would be harmful into water vapor that is removed from the system.
Solution Approach 2:
The invention changes the chemical environment parameter during projection by introducing hydrogen-containing plasma gas. This parameter change enables in-situ reduction of oxide layers on powder particles and in the target bulk, achieving low oxygen content (less than 500 ppm) without requiring expensive high-purity starting materials.
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 method produces targets with an oxygen level less than 500 ppm, achieving a lamellar microstructure and electrical resistivity lower than the theoretical value, enhancing material utilization rates and layer homogeneity, and reducing the risk of arcing and thermal/mechanical failures.
Implementation Method 1
at least a fraction of said compound in the form of a powder composition of said compound is projected by thermal projection onto at least a portion of the surface of the target
Implementation Method 2
powerful cryogenic cooling jets are used, directed towards the target during its construction and distributed around the torch
Implementation Method 3
using a reducing plasma gas mixture to minimize oxide levels
Data Source
Figure 1a~1b
Figure 1c~2a
Figure 2b
AI summary
The invention relates to a target of nominal thickness, comprising at least one compound based on molybdenum, said target being characterised in that it has a lamellar microstructure, an oxygen rate lower than 1000 ppm, preferably lower than 600 ppm, and especially preferably lower than 450 ppm, an electrical resistance of less than 5 times, preferably 3 times, and especially preferably twice the theoretical electrical resistance of the compound.