Molybdenum Sputtering Target Grain Control
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Solution Overview
Problem
High-purity tungsten films used in LSIs face challenges in meeting lower resistance demands, and high-purity molybdenum targets for sputtering have a higher particle generation rate, leading to decreased material yield.
Innovation Solution
A sputtering target with a molybdenum content of 99.99% by mass or more, relative density of 98% or more, and average crystal grain diameter of 400 μm or less, produced through hot pressing and hot isostatic pressing, effectively decreases particle generation during sputtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-purity molybdenum target is used for sputtering, then electric resistance value decreases, but particle generation rate increases
Solution Approach 1:
The patent applies parameter changes by optimizing the crystal grain diameter to 400 μm or less and controlling the relative density to 95% or more. These specific parameter ranges resolve the contradiction by achieving low electric resistance while suppressing particle generation through controlled crystal structure and density
Solution Approach 2:
The patent creates a composite structure within the molybdenum target by controlling the crystal grain size and density distribution. This composite approach with fine-grained high-density molybdenum structure achieves both low resistance and low particle generation rates
2Object-generated harmful factors
If crystal grain diameter is reduced to decrease particles, then manufacturing complexity increases
Solution Approach 1:
The patent uses parameter changes by establishing specific ranges for crystal grain diameter (400 μm or less) and relative density (95% or more). These quantified parameters provide clear manufacturing targets that balance particle reduction with manufacturing feasibility
Solution Approach 2:
The patent applies partial action by achieving sufficient particle reduction at 400 μm crystal grain diameter without pursuing excessive refinement that would complicate manufacturing. This optimal point balances effectiveness with manufacturing complexity
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 sputtering target achieves lower electric resistance values and reduced particle generation, enhancing the reliability of electronic devices with molybdenum thin films.
Implementation Method 1
subjecting the molybdenum powder to hot pressing by applying a load to the molybdenum powder at a temperature of 1350° C. to 1500° C.
Implementation Method 2
subjecting a formed compact obtained by the hot pressing to hot isostatic pressing at a temperature of 1300° C. to 1850° C.
Implementation Method 3
the target having a purity of 99.999% or more, an alkali metal content of 100 ppb or less and a radioactive element content of 10 ppb or less, the method comprising: dissolving metallic molybdenum or a molybdenum compound to produce a molybdenum-containing aqueous solution
Data Source
AI summary
Provided is a sputtering target having a molybdenum content of 99.99% by mass or more, a relative density of 98% or more, and an average crystal grain diameter of 400 μm or less.