Piezoelectric Sputtering Target Grain Control
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Solution Overview
Problem
The challenge is to suppress the generation of particles that become defects during the manufacturing of lead-free piezoelectric thin films using sputtering targets, as existing methods do not effectively address this issue, leading to defects in the thin films.
Innovation Solution
A piezoelectric ceramic sputtering target with a perovskite-type oxide composition of ABO3, where component A includes potassium and/or sodium, and component B includes niobium, with an average crystal grain diameter between 3 μm and 30 μm, is used to control particle generation, thereby reducing defects during film deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sputtering is performed using conventional piezoelectric ceramic targets, then thin films can be deposited, but particles are generated during sputtering that become defects in the thin film
Solution Approach 1:
The invention changes the physical parameter of the target material by controlling the average particle diameter of crystal grains to be 1 μm or less. This parameter change prevents the formation of nodules on the target surface during sputtering, thereby suppressing particle generation and improving thin film quality
Solution Approach 2:
The invention performs preliminary action by pre-controlling the crystal grain size of the piezoelectric ceramic target before sputtering begins. By ensuring the average particle diameter is 1 μm or less in the target material, the invention prevents particle generation during the sputtering process, eliminating the need for post-processing to remove particles
2Reliability
If lead zirconate titanate is used for excellent piezoelectricity, then piezoelectric performance is improved, but environmental harm increases due to lead content
Solution Approach 1:
The invention changes the chemical composition parameter by replacing lead-based materials with lead-free piezoelectric ceramics. This substitution maintains piezoelectric functionality while eliminating environmental harm from lead elution, achieving both performance and environmental goals
Solution Approach 2:
The invention uses lead-free piezoelectric ceramic materials that are environmentally friendly and can be disposed of without harmful effects. While lead-based materials offer slightly superior piezoelectric properties, the lead-free alternatives provide sufficient performance with no environmental harm, making them the preferable choice
3Quantity of substance
If sputtering time is increased to improve film coverage, then film deposition is enhanced, but nodule formation and particle generation increase
Solution Approach 1:
The invention performs preliminary action by pre-controlling the crystal grain size of the target material to 1 μm or less before sputtering begins. This preliminary structural control prevents nodule formation during extended sputtering, allowing longer deposition times to achieve better film coverage without the harmful side effect of particle generation
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 effectively suppresses particle generation, resulting in high-quality lead-free piezoelectric thin films with reduced defects, enhancing the reliability and performance of piezoelectric thin film elements.
Implementation Method 1
a voltage is applied between a substrate (an anode side) on which a thin film is to be deposited and a target (a cathode side) made of material for film deposition which is opposite to the substrate in an inert gas atmosphere such as argon atmosphere, by which ionized rare gas atoms are forced to collide with the target which is a cathode material, and the constituent atoms of the target are knocked out by the energy, whereby a thin film is deposited on the opposite substrate
Implementation Method 2
A piezoelectric ceramic exhibiting a so-called piezoelectric phenomenon is known in which mechanical distortion and stress are generated when an electric field is applied
Data Source
AI summary
A piezoelectric ceramic sputtering target containing a perovskite type oxide represented by chemical formula (I) of ABO3 as a main component, wherein the component A of the chemical formula (I) contains at least K (potassium) and/or Na (sodium), the component B of the chemical formula (I) contains at least Nb (niobium), the piezoelectric ceramic sputtering target is composed of a plurality of crystal grains; and the average particle diameter of the crystal grains is larger than 3 μm and not larger than 30 μm.