Tungsten Sputtering Target with Silver Grains for Low Resistance
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Solution Overview
Problem
Conventional tungsten sputtering targets with nickel fail to sufficiently lower the specific resistance of thin films, particularly for gate electrodes in semiconductor devices, and lack uniformity in resistance, which hinders miniaturization and integration efforts.
Innovation Solution
A sputtering target containing 0.01 to 0.5 wt% Ag, with a W matrix phase and Ag grains of 0.1 to 10.0 μm average size, sintered at 15 to 30 MPa and 1600 to 2000°C, ensuring Ag is not dissolved in the W matrix and maintaining compositional variation below 10%, resulting in a target with 99.999% purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional W target containing Ni is used, then gate electrode can be formed, but specific resistance cannot be sufficiently lowered
Solution Approach 1:
The patent changes the compositional parameter from conventional Ni-containing W target to Ag-containing W target with precisely controlled Ag content (0.01-1.0 wt%). This parameter change fundamentally alters the electrical resistance characteristics, achieving sufficiently low specific resistance that cannot be obtained with Ni-based targets.
Solution Approach 2:
The patent applies local quality by controlling the distribution and grain size of Ag particles within the W matrix. By specifying Ag grain size (0.1-10.0 μm) and compositional uniformity (standard deviation ≤0.005 wt%), the patent creates localized Ag-rich regions that effectively reduce resistance while maintaining overall target integrity and manufacturability.
2Reliability
If Ag is added to W target, then specific resistance is lowered, but compositional uniformity becomes difficult to control
Solution Approach 1:
The patent establishes precise parameter ranges for Ag content (0.01-1.0 wt%) and grain size (0.1-10.0 μm) to simultaneously achieve low specific resistance and compositional uniformity. By controlling these parameters within specific boundaries, the patent resolves the contradiction between resistance reduction and uniformity maintenance.
Solution Approach 2:
The patent implements feedback control by specifying that the standard deviation of Ag composition must be ≤0.005 wt%, providing a quantitative measure of compositional uniformity. This feedback mechanism ensures that manufacturing processes maintain Ag distribution within acceptable limits, preventing excessive compositional variation while achieving low resistance.
3Manufacturing precision
If Ag grain size is reduced, then film uniformity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes the Ag grain size parameter to a specific range (0.1-10.0 μm) that balances film uniformity with manufacturing feasibility. This parameter selection avoids the complexity of ultra-fine grain control while still achieving sufficient film uniformity for semiconductor applications.
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 target effectively forms thin films with significantly lower specific resistance and improved uniformity, enhancing semiconductor device performance by reducing electrical resistance and maintaining device quality.
Implementation Method 1
A tungsten film (gate electrode) is normally formed by sputtering a tungsten target
Implementation Method 2
the mixed powder is sintered at a pressure of 15 to 30 MPa and a temperature of 1600 to 2000° C.
Data Source
AI summary
A sputtering target containing 0.01 to 0.5 wt % of Ag, and remainder being W and unavoidable impurities. The object of the present invention is to provide a sputtering target capable of forming a film having a relatively low specific resistance by sputtering, wherein the obtained film is endowed with good uniformity, and in particular the sputtering target has superior characteristics upon forming thin films for semiconductor devices, as well as to provide a method for producing the foregoing sputtering target.