Two-Stage Downforce Flexure for Uniform Substrate Cleaning
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Solution Overview
Problem
Conventional substrate cleaning systems face challenges in uniformly applying downforce across a batch of substrates, leading to inconsistent cleaning rates and reduced die yield in semiconductor production.
Innovation Solution
The implementation of a two-stage downforce actuator system, which includes a first stage with a linear actuator for coarse vertical translation and a second stage with an expandable flexure for precise, friction-free downforce application, ensures consistent downforce distribution across substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional single-stage linear actuator is used for downforce application, then the device complexity is reduced, but the manufacturing precision of downforce application deteriorates due to inconsistent downforce across substrates
Solution Approach 1:
The downforce actuator is divided into two independent stages: a first stage linear actuator for coarse positioning and a second stage linear actuator for fine downforce control. This segmentation allows each stage to perform its specific function optimally, with the first stage handling large movements and the second stage providing precise downforce adjustment, thereby improving downforce uniformity without requiring a completely complex new design
Solution Approach 2:
The system dynamically coordinates the operation of two linear actuators in sequence. The first stage actuator operates to position the carrier head, then the second stage actuator operates to apply the precise downforce. This dynamic, multi-phase operation allows the system to achieve high manufacturing precision through coordinated control of multiple components rather than a single complex actuator
2Productivity
If high downforce is applied to increase cleaning rate, then the productivity is improved, but the manufacturing precision of uniform cleaning deteriorates due to excessive force causing non-uniform cleaning across the substrate surface
Solution Approach 1:
The downforce is applied dynamically in two phases: first through the first stage actuator for positioning, then through the second stage actuator for controlled downforce application. This dynamic, staged approach allows the system to apply sufficient downforce for high cleaning rates while maintaining precise control to ensure uniform distribution across the substrate surface, preventing the non-uniform cleaning that occurs with excessive single-stage force
3Manufacturing precision
If a two-stage downforce actuator system is implemented, then the manufacturing precision of downforce application is improved, but the device complexity increases due to additional actuators and control mechanisms
Solution Approach 1:
The actuator system is segmented into two functional stages with distinct roles. The first stage handles coarse positioning and initial downforce, while the second stage handles fine downforce adjustment. This segmentation improves precision by dividing the control function into manageable parts, each optimized for its specific range of operation
Solution Approach 2:
Both stages use linear actuators, which are relatively standard components. The first stage actuator serves dual purposes of positioning and initial downforce application, while the second stage provides fine adjustment. This multi-functionality reduces the need for completely unique or complex specialized components, balancing precision improvement with manageable device 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
This solution enables more repeatable and finely tuned downforce application, improving the uniformity of substrate cleaning and increasing die yield by ensuring consistent cleaning across all substrates in a batch.
Implementation Method 1
The expandable flexure may expand to vertically transfer the carrier head and the motor downward
Implementation Method 2
a first stage that includes a linear actuator that is operable to vertically translate the carrier head and the motor
Data Source
AI summary
Exemplary chemical mechanical cleaning systems may include a carrier head. The systems may include a motor that is coupled with the carrier head. The motor may be operable to rotate the carrier head about a central axis of the carrier head. The systems may include a two-stage downforce actuator that is operable to vertically translate the carrier head and the motor between a raised position and a cleaning position. The downforce actuator may include a first stage that includes a linear actuator that is operable to vertically translate the carrier head between the raised position and at least an upper 50% of a vertical travel distance between the raised and cleaning positions. The downforce actuator may include a second stage that includes an expandable flexure that is operable to vertically translate the carrier head between the cleaning position and no greater than a lower 50% of the vertical distance.