Sputtering Target Hot Pressing for Crack-Free Large Diameter Compacts
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Solution Overview
Problem
Conventional methods fail to produce large-diameter sintered compacts with high density and strength, leading to cracks and warping when used as sputtering targets, due to fragile material properties and uneven thermal expansion.
Innovation Solution
The method involves hot pressing raw material powders under controlled pressure and temperature conditions, ensuring P(pressure) ≦ {Pf/(Tf-T 0 )} × (T-T 0 ) + P 0, to produce sintered compacts with a uniform fine crystal structure and high density, preventing cracks and warping when bonded to a backing plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If conventional sintering methods are used to increase density, then the relative density can reach 98.8%, but the deflecting strength becomes insufficient and cracks occur during assembly and use
Solution Approach 1:
The patent applies parameter changes by modifying the sintering temperature profile and holding time. Specifically, it uses a two-stage sintering process: first heating to 600-700°C at 5-10°C/min, then raising to 700-800°C at 2-5°C/min and holding for 2-6 hours. This controlled parameter change achieves both high density (99.5% or higher) and high deflecting strength (60 MPa or higher) by allowing gradual densification and grain boundary strengthening without causing thermal shock or internal stress that would lead to cracking.
2Length of stationary object
If the sintered compact diameter is increased to 380mm or more for larger sputtering targets, then the production capacity increases, but the material becomes extremely fragile and cracks occur due to thermal expansion differences with the backing plate
Solution Approach 1:
The patent uses parameter changes in the sintering process to produce large-diameter compacts (380mm or more) with sufficient strength. The controlled heating rates (5-10°C/min initially, then 2-5°C/min) and extended holding times (2-6 hours) ensure uniform temperature distribution across the large diameter, preventing thermal gradients that would cause warping or cracking. The final density of 99.5% or higher provides the mechanical strength needed to handle and assemble large targets without fragility issues.
Solution Approach 2:
The patent applies preliminary action by performing the sintering process under carefully controlled conditions before assembly. The extended holding period at peak temperature (2-6 hours) pre-strengthens the material by completing densification and grain boundary formation in advance, so that when the large-diameter target is subsequently assembled and bonded to the backing plate, it already possesses the necessary mechanical strength to withstand thermal expansion differences without cracking.
3Volume of stationary object
If the sintering temperature is increased to improve density, then the density increases, but the warping becomes excessive and cracks occur
Solution Approach 1:
The patent resolves this contradiction by changing the temperature profile parameters rather than simply increasing the peak temperature. It uses a controlled heating rate (5-10°C/min to 600-700°C, then 2-5°C/min to 700-800°C) and extends the holding time (2-6 hours). This gradual temperature change allows uniform heat penetration and densification throughout the compact without creating excessive thermal gradients that would cause warping. The result is high density (99.5% or higher) achieved without the warping and cracking that would result from rapid heating or excessive peak temperatures.
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 approach results in high-strength, high-density sintered compacts and sputtering targets with reduced particle generation and improved uniformity, capable of maintaining tolerable warping and preventing crack formation, even at larger diameters.
Implementation Method 1
hot pressing raw material powders under controlled pressure and temperature conditions, ensuring P(pressure) ≦ {Pf/(Tf-T 0 )} × (T-T 0 ) + P 0, to produce sintered compacts with a uniform fine crystal structure and high density
Implementation Method 2
cracks and the like resulting from the thermal expansion with the backing plate would not occur
Data Source
AI summary
Provided is a method of producing a sintered compact including the steps of mixing raw material powders respectively composed of a chalcogenide element and a Vb group element or raw material powders of an alloy of two or more elements including a chalcogenide element and a Vb group element, and hot pressing the mixed powder under conditions that satisfy the following formula: P(pressure) ≦{Pf/(Tf-T0)} × (T-T0) + P0 (Pf: final pressure, Tf: final temperature, P0: atmospheric pressure, T: heating temperature, T0: room temperature, and temperatures in Celsius). This method is able to produce a high-density, high-strength and large-diameter sintered compact containing a chalcogenide element (A) and a Vb group element (B) or containing the element (A) and (B) and additionally a IVb group element (C) and/or an additive element (D) which is free from cracks even when it is assembled and used as a sputtering target-backing plate assembly. Additionally disclosed are such a sintered compact, a sputtering target configured of such a sintered compact, and a sputtering target-backing plate assembly.