Cylindrical Sputtering Target with Bonded Segments
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Solution Overview
Problem
Long cylindrical sputtering targets used in flat panel displays and solar cells face issues with steps and misalignments between stacked target materials, leading to abnormal electrical discharge and reduced production yield during film formation.
Innovation Solution
A cylindrical sputtering target is formed by bonding multiple target materials to a cylindrical base with a bonding material, ensuring a step of 0.5 mm or less between adjacent materials, and using a gap between them to prevent collision and thermal expansion, with chamfered edges to reduce electric field concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If multiple cylindrical target materials are stacked to form a long cylindrical sputtering target, then the target length is increased to enable film formation on large substrates, but steps occur between the outer peripheral faces of adjacent target materials leading to abnormal electrical discharge
Solution Approach 1:
The long cylindrical sputtering target is divided into multiple smaller cylindrical target materials stacked along the length direction. Each target material has a length of 300 mm or more but less than 600 mm, and they are arranged with gaps between them to prevent thermal expansion collision while maintaining overall target functionality.
Solution Approach 2:
The outer peripheral faces of adjacent cylindrical target materials are configured to have steps of 0.5 mm or less in the stacked direction. This local precision control at the interfaces between segments prevents abnormal electrical discharge while allowing the overall target to maintain sufficient length for large substrate coverage.
2Strength
If cylindrical target materials are stacked with gaps to prevent thermal expansion collision, then target material breaking is prevented, but steps occur between outer peripheral faces reducing manufacturing precision
Solution Approach 1:
The gap between adjacent cylindrical target materials is controlled within specific ranges: 0.1 mm or more and 0.5 mm or less in the radial direction, and 1 mm or more and 3 mm or less in the axial direction. These parameter optimizations prevent thermal expansion collision while minimizing step formation.
Solution Approach 2:
A bonding material is provided in the gaps between adjacent cylindrical target materials. This bonding material has thermal expansion characteristics that compensate for the gaps, preventing target material collision during thermal expansion while maintaining alignment precision through controlled step heights of 0.5 mm or less.
3Manufacturing precision
If the outer peripheral faces of adjacent target materials are precisely aligned, then steps are minimized preventing electrical discharge, but the complexity of assembly increases
Solution Approach 1:
The cylindrical target materials are pre-formed with controlled dimensions and outer peripheral face flatness before assembly. The steps between outer peripheral faces are controlled to be 0.5 mm or less through precise manufacturing of individual components, which simplifies the final assembly process while maintaining high alignment precision.
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 configuration inhibits abnormal electrical discharge and particles, enhancing the production yield in the film-forming process by maintaining a stable electric field and preventing target material collision during sputtering.
Implementation Method 1
bonding a plurality of stacked cylindrical target materials to an outer peripheral face of a cylindrical base with a bonding material
Implementation Method 2
a divided portion where adjacent cylindrical target materials are arranged with a gap therebetween in order to prevent the cylindrical target materials from colliding with each other and breaking as being thermally expanded by plasmas during sputtering
Implementation Method 3
cylindrical targets having a length of 3 m or more in order to form thin films on the substrates having thus increased sizes. Such long cylindrical sputtering targets are used in magnetron rotary cathode sputtering apparatus
Data Source
AI summary
Provided is a cylindrical sputtering target which attains a high production yield in a film-forming process even when a film is formed by sputtering with a long cylindrical sputtering target constituted by a plurality of cylindrical target materials.A multi-divided cylindrical sputtering target formed by bonding a cylindrical base and a plurality of cylindrical target materials together with a bonding material has a divided portion where adjacent cylindrical target materials are arranged with a gap therebetween, while outer peripheral faces of the adjacent cylindrical target materials have a step of 0.5 mm or less therebetween in the divided portion. Such a target is obtained by fixing the cylindrical target materials with reference to the outer peripheral faces of the cylindrical target materials when arranging the cylindrical target materials with reference to the cylindrical base.