ESC Electrode Circuit Detection of Wafer Bow During Clamping
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Solution Overview
Problem
Wafer bow during semiconductor fabrication can lead to undesirable fabrication results, particularly at high temperatures or in plasma applications, making it difficult to detect and mitigate.
Innovation Solution
An apparatus and method using an RF blocking filter, DC blocking filter, and a controller to measure wafer state characteristics by injecting an input signal and calculating wafer state characteristics based on output signal phase differences, estimating wafer bow through resonant frequency and capacitance analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrostatic chucks are used to grip wafers during fabrication, then wafer clamping is achieved, but wafer bow detection becomes difficult at high temperatures or in plasma applications
Solution Approach 1:
The patent introduces an intermediary detection circuit that measures electrical parameters (capacitance, impedance, or resistance) between the electrostatic chuck electrodes and the wafer. This intermediary electrical measurement allows indirect detection of wafer bow without directly observing the physical deformation, thereby solving the detection difficulty in high temperature and plasma environments where direct measurement is challenging.
Solution Approach 2:
The patent replaces direct mechanical/optical measurement of wafer bow with electrical measurement methods. By measuring electrical parameters such as capacitance, impedance, or resistance through the electrostatic chuck circuitry, the system substitutes complex mechanical or optical detection systems with simpler electrical measurements that can be performed accurately in high temperature and plasma conditions.
2Productivity
If wafer bow is not detected and mitigated, then fabrication process continues, but undesirable fabrication results occur
Solution Approach 1:
The patent implements a feedback mechanism where the detection circuit continuously monitors electrical parameters during fabrication. When wafer bow exceeds predetermined thresholds, the system generates alerts or automatically adjusts electrostatic chuck voltages to correct the bow. This real-time feedback loop ensures fabrication precision is maintained while allowing continuous production, as the system can dynamically compensate for wafer deformation without interrupting the fabrication process.
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
Effectively detects and quantifies wafer bow, preventing declamping and ensuring proper clamping, thereby improving fabrication accuracy and reducing defects.
Implementation Method 1
an RF blocking filter: a DC blocking filter
Implementation Method 2
an RF blocking filter: a DC blocking filter
Implementation Method 3
the input signal has a carrier frequency corresponding to a resonant frequency of the circuit associated with the plurality of electrodes, the RF blocking filter, and the DC blocking filter
Implementation Method 4
Electrostatic chucks are frequently used during semiconductor fabrication to grip or clamp a wafer undergoing fabrication
Data Source
AI summary
Various embodiments herein relate to apparatuses and methods for wafer state detection. In some embodiments, an apparatus for wafer state detection is provided, the apparatus comprising: an RF blocking filter; a DC blocking filter; and a controller coupled to a plurality of electrodes associated with an electrostatic chuck (ESC) via the RF blocking filter and the DC blocking filter, wherein the controller is configured to: cause an input signal to be injected in an input side of a circuit associated with the plurality of electrodes, the RF blocking filter, and the DC blocking filter, wherein the input side corresponds to a first electrode; measure characteristics of an output signal at an output side of the circuit, wherein the output side corresponds to a second electrode; and calculate wafer state characteristics of a wafer positioned on a surface of a platen based on the characteristics of the output signal.