Wafer Grinding Force Measurement via Thin Film Sensor
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Solution Overview
Problem
Current methods for measuring wafer grinding force during semiconductor wafer thinning are inadequate, as they rely on indirect and insensitive parameters like spindle current, which fail to accurately reflect the grinding force, leading to surface damage and reduced fabrication yield.
Innovation Solution
A device and method utilizing a thin film pressure sensor placed between the wafer and a worktable, with a data acquisition and wireless transmission module, allowing for real-time monitoring of grinding force through a wireless signal, providing precise and direct measurement of the grinding force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If spindle current monitoring is used to indirectly reflect grinding force, then the operation is simple, but the measurement precision is insufficient and cannot meet precision machining demands
Solution Approach 1:
The patent replaces the electrical measurement method (spindle current monitoring) with a direct mechanical measurement method by installing a force sensor on the air spindle to directly detect grinding force, thereby improving measurement precision while maintaining operational simplicity
Solution Approach 2:
The patent introduces a force sensor as an intermediary device between the grinding system and the measurement system, enabling direct and accurate measurement of grinding force without relying on indirect electrical parameters
2Measurement precision
If force sensors are installed on the air spindle to track grinding force through spindle deformation, then grinding force can be measured, but the measured force is not the actual grinding force in the contact area and the device complexity increases
Solution Approach 1:
The patent uses the air spindle itself as an intermediary transmission mechanism to transfer the grinding force from the wafer contact point to the force sensor mounted on the spindle body, enabling accurate measurement of contact area grinding force without direct sensor installation at the contact point
Solution Approach 2:
The air spindle serves dual functions: both as the rotating support for wafer grinding and as the force transmission path to the sensor, eliminating the need for separate measurement infrastructure and reducing device complexity
3Reliability
If wired signal transmission is used for sensor data transmission, then the system is stable, but it does not reflect the real grinding state and causes signal winding issues during wafer assembly
Solution Approach 1:
The patent replaces wired electrical signal transmission with wireless signal transmission technology, eliminating physical connections that cause signal winding issues during wafer assembly while maintaining signal stability and accurately reflecting real-time grinding state
Solution Approach 2:
The patent extracts and removes the physical wiring from the signal transmission path, eliminating the source of signal winding problems during wafer assembly while maintaining reliable data transmission between the sensor and external systems
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
Enables real-time monitoring of grinding force, reducing surface damage and improving processing quality by providing high precision and avoiding signal winding issues during wafer assembly.
Implementation Method 1
a thin film pressure sensor... monitoring the grinding force voltage signal in real time
Data Source
AI summary
A method and apparatus for on-line measurement of the wafer thinning and grinding force, related to the field of ultra-precision machining of semiconductor wafer materials. The grinding force measuring apparatus comprises a semiconductor wafer, a worktable, a bearing table, a thin film pressure sensor, and a data processing and wireless transmission module. The grinding force measuring method includes sensor calibration based on the testing device and on-line measurement of grinding force. Using the grinding force measuring device and method provided by the invention, the grinding force in the semiconductor wafer grinding process can be monitored in real time, which is of great significance for semiconductor processing and reducing grinding damage. The invention also has the following characteristics: the sensor adopts a film pressure sensor, the response time is short, and the test precision is high; the data transmission adopts a wireless transmission design, thus the grinding force can be monitored in real time during the wafer and spindle rotation process and the risk of winding during wafer rotation can be avoided. The sensor adopts a distributed design, which can monitor the distribution of the grinding force along the wafer radial direction or crystal orientation.