Sputtering Target Groove Design for Mask Blank Particle Control
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Solution Overview
Problem
The manufacturing of mask blanks for short wavelengths, such as ArF or F2 excimer lasers, faces challenges in reducing variations in phase angle and transmittance, as well as the generation of large particles caused by the elution of the bonding agent in the sputtering target, which hinders mass production and productivity.
Innovation Solution
A sputtering target design where the target member and backing plate are bonded with a bonding agent, and a metal film is formed on the side wall to prevent the bonding agent's exposure, with the target member having a larger surface area than the bonding portion and a flange extending from the periphery, and the target is positioned at an angle to the substrate to reduce particle generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a sputtering target with bonding agent is used to bond target member to backing plate, then the target can be assembled and manufactured, but particles are generated on the substrate due to bonding agent elution
Solution Approach 1:
The harmful bonding agent is extracted from the problematic location by forming a groove that separates it from the sputtering atmosphere, preventing its elution onto the substrate while maintaining its bonding function
Solution Approach 2:
A groove structure is introduced as an intermediary element between the bonding agent and the sputtering atmosphere, acting as a barrier that prevents the bonding agent from contacting the substrate while allowing the target to function normally
2Device complexity
If the sputtering target is positioned with target surface downward in gravity direction, then the apparatus structure is simplified, but bonding agent elutes more easily causing increased particle generation
Solution Approach 1:
The bonding agent is extracted from the gravity-driven elution path by forming a groove that contains it, preventing gravity from causing it to flow onto the substrate while maintaining the simple downward-facing target configuration
Solution Approach 2:
The groove acts as a containing structure that restricts the bonding agent to a specific region, preventing its uncontrolled movement under gravity while maintaining the simplicity of the overall target design
3Productivity
If mass production of mask blanks is implemented, then productivity increases, but particle generation accumulates and deteriorates yield
Solution Approach 1:
The bonding agent is extracted and isolated in a groove structure, preventing it from generating particles during repeated sputtering operations that characterize mass production, thereby maintaining high yield across large production volumes
Solution Approach 2:
The groove structure is pre-formed in the target before sputtering begins, proactively preventing particle generation before it can occur during mass production operations
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 design effectively reduces the generation of particles on the substrate, allowing for stable and continuous production of mask blanks with reduced phase angle and transmittance variations, enhancing mass productivity for short-wavelength applications.
Implementation Method 1
a sputtering target of which target member and backing plate are bonded to each other with a bonding agent
Implementation Method 2
a metal film is formed on a side wall of the sputtering target so as to prevent the bonding agent from being exposed
Implementation Method 3
the thin film is formed by a sputtering method using a sputtering target
Data Source
AI summary
A sputtering target for manufacturing a mask blank having a backing plate 5 where a portion for bonding a target member 4 is protruded like the convex with respect to a base portion 5′, and the target member 4 being formed to have a larger surface area than the area of the bonding portion of the backing plate 5 with extending from the bonding portion over a whole periphery with a bonding agent 30 interposed in-between, and further a metal 40 is deposited to a concave portion formed by a combination of the two structures in such a manner that the elution of the bonding agent 30 can be sealed.