Wafer Polishing Device with Real-Time Thickness Feedback Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing polishing devices for semiconductor wafers face challenges in achieving uniform thickness profiles due to non-uniform pressing forces, which can lead to insufficient or excessive polishing, especially with complex transistor structures and increasing circuit densities, requiring improved precision and planarization techniques.
Innovation Solution
A polishing device with a pressing unit and a control unit that adjusts the pressing force based on real-time thickness measurements, also controlling the periphery's influence on the pressing force to ensure uniform polishing across the wafer surface, including edge regions, using a mechanism with multiple pressure chambers and a retainer member to maintain precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If uniform pressing force is applied across the entire wafer surface, then polishing consistency is improved, but initial thickness distribution cannot be corrected
Solution Approach 1:
The pressing unit is divided into multiple independent pressure chambers (first, second, third pressure chambers) that can apply different pressing forces to different regions of the wafer. This segmentation enables regional control of polishing pressure to correct initial thickness distribution while maintaining overall polishing consistency.
Solution Approach 2:
Different regions of the wafer are assigned different pressing forces based on their initial thickness characteristics. The first pressure chamber applies a first pressing force to a first region, the second pressure chamber applies a second pressing force to a second region, and the third pressure chamber applies a third pressing force to a third region, allowing local optimization of polishing rates to correct thickness non-uniformity.
2Productivity
If pressing force is increased to improve polishing rate, then productivity is improved, but non-uniform polishing and potential damage occur
Solution Approach 1:
The pressing forces in different pressure chambers are dynamically adjusted based on real-time thickness measurements. The control unit modifies the pressing forces during the polishing process to maintain optimal polishing rates while preventing non-uniform polishing and potential wafer damage.
Solution Approach 2:
A thickness measurement unit continuously measures the wafer thickness during polishing, and the control unit uses this feedback information to adjust the pressing forces in different pressure chambers. This closed-loop control ensures high polishing rates while maintaining uniformity and preventing damage.
3Manufacturing precision
If complex control mechanisms are added to correct thickness distribution, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The control system is segmented into multiple independent pressure chambers, each controlled by the control unit based on thickness measurement feedback. This modular approach enables precise thickness profile control while keeping the control architecture manageable through clear functional separation.
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 enables highly precise polishing by dynamically adjusting pressing forces, ensuring uniform thickness profiles and preventing damage by limiting control within predetermined values, effectively addressing the challenges of non-uniformity and complexity in semiconductor wafer processing.
Implementation Method 1
a thickness measurement unit that measures a thickness of the object to be polished during polishing of the object to be polished
Implementation Method 2
a pressure chamber formed of a membrane is provided in a lower portion of the substrate holding device and a fluid such as a pressurized air is supplied into the pressure chamber so that polishing is performed while the semiconductor wafer being pressed against the polishing surface of the polishing pad by a fluid pressure via the membrane
Implementation Method 3
the chemical mechanical polishing polishes a substrate such as a semiconductor wafer by using a polishing device and bringing the substrate into sliding contact with a polishing surface while supplying a polishing liquid containing abrasive grains such as silica (SiO2) onto the polishing surface
Data Source
AI summary
The polishing device includes an edge chamber that presses the surface to be polished against the polishing pad by pressing a back side of the surface to be polished of the wafer, a thickness measuring unit that estimates a remaining film profile of the surface to be polished of the wafer in realtime during polishing, and a closed loop control device that controls a pressing force on the back side of the surface to be polished by the edge chamber in accordance with a measurement result by the thickness measuring unit during polishing. The closed loop control device controls not only the pressing by the edge chamber during polishing, but also the pressure of a retainer ring as a periphery of the edge chamber affecting the pressing of the surface to be polished against the polishing pad.