Refractory Metal Sputtering Target Density via Cold Isostatic Pressing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Sintering techniques have not been effectively employed in producing high-density sputtering targets due to inconsistent density achievement, which affects the performance of refractory metal products.
Innovation Solution
A process involving cold isostatic pressing of refractory metal powders followed by a controlled heating schedule to achieve densities greater than 97% theoretical, resulting in fine grain size, uniform texture, and the production of sputtering targets with improved thin film deposition rates and resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sintering techniques are used to produce refractory metal products, then production cost is reduced, but density consistency is insufficient
Solution Approach 1:
The patent applies preliminary action by performing cold isostatic pressing before sintering to pre-densify the powder compact. This preliminary densification step ensures that the subsequent sintering process can achieve consistent high density (>97% theoretical density) while maintaining cost advantages, resolving the contradiction between production cost and density consistency.
2Manufacturing precision
If traditional hot isostatic pressing and rolling are used, then high density is achieved, but production cost increases
Solution Approach 1:
The patent segments the traditional hot isostatic pressing process into two separate steps: cold isostatic pressing followed by controlled atmosphere sintering. This segmentation allows each step to be optimized independently - cold pressing achieves initial densification at lower cost, while sintering achieves final high density with consistent quality, thereby reducing overall production cost while maintaining density levels.
3Ease of manufacture
If cold isostatic pressing followed by sintering is used, then production cost is reduced, but achieving high density consistently is difficult
Solution Approach 1:
The patent applies parameter changes by carefully controlling multiple process parameters: cold isostatic pressing pressure (10-30 tons/inch²), sintering temperature (2800-3600°F), heating rate (50-120°F per hour), and atmosphere composition. These controlled parameter changes ensure consistent achievement of >97% theoretical density while maintaining the cost advantages of the cold pressing-sintering route.
4Productivity
If rapid heating is applied during sintering, then processing time is reduced, but grain growth and texture non-uniformity increase
Solution Approach 1:
The patent applies periodic action through a multi-stage heating schedule with controlled rates (50-120°F per hour) and extended holding periods at each temperature stage. This periodic, staged heating approach allows gradual and uniform grain growth, achieving fine grain size and random texture while maintaining reasonable processing time, thus resolving the contradiction between productivity and grain uniformity.
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 high-density refractory products with fine grain size and random texture, leading to higher deposition rates, lower resistivities, and reduced non-uniformity in thin films, while offering a cost advantage over traditional methods like hot isostatic pressing and rolling.
Implementation Method 1
cold isostatically pressing a refractory metal powder at a pressure of from about 10,000 psi to about 65,000 psi to form a pressed product
Implementation Method 2
heating said pressed product with the temperature being increased at a rate of from about 20 to about 120° F. per hour to a first temperature of from about 300 to about 1000° F. and holding at said first temperature for a period of from about one to about thirty-eight hours
Implementation Method 3
The present invention is directed to a process for making refractory metal products, and particularly sputtering targets
Data Source
AI summary
The present invention is directed to a process for producing high density, refractory metal products via a press/sintering process. The invention is also directed to a process for producing a sputtering target and to the sputtering target so produced.