Gold and Platinum Sputtering Target Grain Refinement
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Solution Overview
Problem
High-purity gold and platinum sputtering targets often exhibit non-uniform crystal grain sizes and textures, leading to unstable film deposition characteristics during sputtering due to the coarse nature of the materials, which is difficult to address with existing methods.
Innovation Solution
A multi-stage processing method involving ingot production, primary and secondary forging, cross-rolling, and heat treatment is employed to introduce distortions and control crystal grain size, ensuring uniformity and preventing coarsening, resulting in targets with average crystal grain sizes between 5 to 50 μm and a 20% tolerance across the target surface and thickness directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high purity gold or platinum is used for sputtering targets, then the material's chemical inertness and purity are improved, but the crystal grain size becomes coarse and non-uniform
Solution Approach 1:
The patent applies preliminary action by performing multi-stage forging and rolling processes before the final sputtering target formation. These preliminary mechanical processing steps introduce controlled distortions and refine the crystal structure in advance, ensuring fine and uniform crystal grains (10-100 μm) are established before casting into the final target shape, thereby preventing coarse grain formation later
Solution Approach 2:
The patent employs parameter changes by controlling the temperature range during heat treatment (0.3 to 0.5 Tm, where Tm is melting point) and adjusting the number of forging passes (5 or more times). These parameter optimizations enable recrystallization that produces fine equiaxial crystals while maintaining material purity, resolving the contradiction between purity and grain uniformity
2Reliability
If the crystal grain size is reduced to improve film deposition stability, then the sputtering rate stability is improved, but the manufacturing process complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the manufacturing process into distinct stages: primary forging, intermediate rolling, secondary forging, and final heat treatment. Each stage performs a specific function in refining the crystal structure, with the forging process divided into multiple passes (5 or more times). This segmented approach makes the complex process manageable and controllable while achieving the desired fine grain structure
Solution Approach 2:
The patent implements continuity of useful action by maintaining the material in a processed state through continuous mechanical working (forging and rolling) without allowing excessive recovery or recrystallization between steps. The multi-pass forging with intermediate cooling maintains accumulated distortion energy that drives fine grain formation, ensuring the useful action of grain refinement continues throughout the process
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 effectively stabilizes film deposition characteristics by achieving a uniform and fine crystal grain structure, enhancing the sputtering process's stability and consistency.
Implementation Method 1
By performing a heat treatment in an appropriate temperature range in this state, many fine crystal grains can be produced by recrystallization through the sub-grain
Implementation Method 2
a heat treatment step for heat-treating the target-shaped ingot obtained in the cross-rolling processing step in a fourth temperature range of 0.3 to 0.5 Tm
Implementation Method 3
a secondary forging step for determining six directions of upper, lower, left, right, front, and rear directions for the cooled primary forged ingot and further forging the cooled primary forged ingot from the six directions
Data Source
AI summary
Method of producing a target having a small average crystal grain size of gold or platinum and having a uniform crystal grain size in an in-plane direction of a target surface and a thickness direction of the target in order to further stabilize film deposition characteristics during sputtering. The method for producing a gold or platinum target includes an ingot production step for casting molten gold or platinum to obtain an ingot; a primary forging step for forging the ingot in a first temperature range; a step for cooling the primary forged ingot to a second temperature range lower than the first temperature range; a secondary forging step for determining six directions for the cooled primary forged ingot and further forging the cooled primary forged ingot from the six directions in the second temperature range; a cross-rolling processing step for adjusting the temperature of the secondary forged ingot to a third temperature range and subjecting the secondary forged ingot to cross-rolling processing to form the secondary forged ingot into a target shape; and a heat treatment step for heat-treating the target-shaped ingot in a fourth temperature range.