GeSbTe Sintered Target Oxygen Control for Stable DC Sputtering
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Solution Overview
Problem
Conventional Ge—Sb—Te-based sintered compact targets exhibit low thermal conductivity and electric conductivity, leading to heat accumulation, particle generation, and arcing issues during sputtering, limiting stable DC sputtering and deposition efficiency.
Innovation Solution
The raw powder for the sintered compact undergoes oxidation treatment followed by high-vacuum hot press in a reduction atmosphere, forming low-resistance crystal phases at the grain boundary, resulting in a target with enhanced thermal conductivity and reduced electric resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional Ge—Sb—Te-based sintered compact is used with high purity raw powder, then the material achieves high density (relative density ~98.8%), but the thermal conductivity remains low and electric resistivity exceeds 0.26 mΩ·cm
Solution Approach 1:
The invention changes the oxygen concentration parameter in the sintered compact from trace amounts (conventional) to a specific range of 0.1-15%, which fundamentally alters the electrical and thermal properties. By controlling oxygen content during sputtering deposition, the patent achieves both acceptable density and significantly improved thermal conductivity while maintaining electric resistivity within usable ranges.
Solution Approach 2:
The invention introduces local quality variations by creating oxygen-rich regions within the sintered compact structure. The oxygen is preferentially incorporated during the sputtering process, creating localized modifications in the material properties that improve overall thermal conductivity without compromising the bulk density.
2Ease of manufacture
If conventional Ge—Sb—Te-based sintered compact with low thermal conductivity is used, then the target can be manufactured, but heat accumulates within the target causing components with high vapor pressure to volatilize and particles to be generated easily
Solution Approach 1:
By changing the thermal conductivity parameter through controlled oxygen incorporation (0.1-15% oxygen concentration), the patent prevents heat accumulation that would otherwise cause volatilization and particle generation. This parameter change allows the target to dissipate heat effectively during sputtering, eliminating the harmful effects while maintaining manufacturability.
3Ease of operation
If DC sputtering is used with conventional low electric conductivity target, then charge-up occurs and arcing cannot be completely eliminated, requiring pulsed DC sputtering which reduces deposition efficiency
Solution Approach 1:
The invention changes the electric resistivity parameter by controlling oxygen concentration (0.1-15%) in the sintered compact. This optimization allows DC sputtering to proceed without excessive charge-up and arcing, enabling continuous deposition at high efficiency without requiring pulsed modes that reduce productivity.
4Reliability
If oxygen concentration in the film is increased to deposit GeSbTe film with high electric resistivity, then electric resistance increases, but thermal conductivity decreases and ceramization occurs
Solution Approach 1:
The invention applies local quality by introducing oxygen in controlled, localized amounts (0.1-15% concentration range) during sputtering. This creates optimal regions with enhanced electric resistance while avoiding excessive oxygen that would cause ceramization and reduce thermal conductivity. The local optimization allows simultaneous achievement of both properties.
Solution Approach 2:
The patent optimizes the oxygen concentration parameter within a specific window (0.1-15%) during sputtering deposition. This precise parameter control achieves the desired electric resistance increase while maintaining thermal conductivity above acceptable thresholds, preventing the ceramization that occurs with higher oxygen levels.
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 achieves a sintered compact with thermal conductivity of 2.5 W/mK or more and electric resistivity of 0.30 mΩ·cm or less, enabling stable DC sputtering, reducing arcing and particle generation, and improving deposition efficiency.
Implementation Method 1
Formation of films by the sputtering method is performed by physically colliding positive ions such as Ar ions to a target located on a cathode side, ejecting materials configuring the target with the collision energy, and laminating a film similar in composition to the target material onto the anode-side substrate
Implementation Method 2
The raw powder for the sintered compact undergoes oxidation treatment followed by high-vacuum hot press in a reduction atmosphere, forming low-resistance crystal phases at the grain boundary
Implementation Method 3
sintering, via hot press, the raw powder having high purity and a prescribed grain size
Implementation Method 4
high-vacuum hot press in a reduction atmosphere
Data Source
AI summary
Provided is a target of sintered compact essentially consisting of an element of (A), an element of (B) and an element of (C) below, wherein the thermal conductivity is 2.5 W/mK or more and the oxygen concentration is 5000 ppm or more:(A) one or more chalcogenide elements selected from S, Se, and Te;(B) one or more Vb-group elements selected from Bi, Sb, As, P, and N; and(C) one or more IVb-group elements or IIIb-group elements selected from Ge, Si, C, Ga, and In. Also provided is a technology enabling stable DC sputtering, and stable and high-speed sputtering by applying high electric power, by improving heat accumulation and diffusion of volatile components due to the sputtering target having high thermal conductivity and low electric resistivity.