Electrostatic Chuck Substrate Warping Detection via AC Impedance
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Solution Overview
Problem
The challenge in semiconductor manufacturing is managing silicon wafers during processing to prevent damage caused by warping and thermal expansion differences, which existing electrostatic chucks cannot accurately monitor, leading to reduced productivity and yield.
Innovation Solution
A method involving an electrostatic chuck with a dielectric chuck plate, rib portions, and gas introduction means, where AC current and gas flow are monitored to detect substrate warping, allowing for real-time adjustment of voltage and gas flow to prevent damage, by measuring changes in impedance and gas flow due to warping directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If AC current monitoring is used to detect chuck plate wear, then the limit of use can be judged quickly, but substrate warping during processing cannot be detected
Solution Approach 1:
The patent makes the AC power supply serve multiple functions: it not only monitors chuck plate wear through current measurement but also detects substrate warping state by measuring changes in capacitance. This multi-functional approach allows simultaneous monitoring of both chuck plate condition and substrate state without adding separate detection systems.
Solution Approach 2:
The patent introduces capacitance measurement as an intermediary parameter that reflects substrate warping. By measuring the capacitance between the chuck plate and substrate, the system indirectly detects substrate warping state without direct physical contact or additional sensors on the substrate.
2Productivity
If larger diameter and thinner wafers are used to improve productivity, then processing capacity increases, but warping and damage risk increase
Solution Approach 1:
The patent implements real-time feedback monitoring of substrate state through AC current and capacitance measurements. By continuously monitoring these parameters during processing, the system can detect warping early and adjust processing conditions or alert operators before damage occurs, ensuring reliability even with thinner, more warping-prone wafers.
Solution Approach 2:
The patent performs preliminary monitoring of substrate state before damage occurs. By detecting changes in AC current and capacitance that indicate warping, the system can take preventive actions such as adjusting processing parameters or stopping the process before the substrate is damaged, thereby maintaining reliability with high-productivity thin wafers.
3Reliability
If real-time substrate state monitoring is implemented to prevent damage, then yield improves, but system complexity increases
Solution Approach 1:
The patent uses the existing AC power supply circuit to perform multiple measurement functions (current monitoring for wear detection and capacitance measurement for warping detection) without adding separate dedicated monitoring systems. This approach prevents substrate damage while avoiding significant increases in system 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 method accurately manages substrate warping, preventing damage during processing and handling, thereby improving productivity and yield by enabling timely adjustments to substrate attraction and handling.
Implementation Method 1
the electrostatic chuck having a plurality of electrodes, and a dielectric chuck plate, and attracts the substrate by application of a predetermined voltage between the electrodes
Implementation Method 2
Inert gas such as Ar gas or the like is supplied to the inner space through a gas passage which is formed in the chuck main body. By thus forming an inert gas atmosphere in the inner space to be defined by the rib portion and the rear surface of the wafer, the heat transmission to the wafer is assisted
Implementation Method 3
the chuck main body has assembled therein, e.g., a resistance heating type of heating means
Data Source
AI summary
The electrostatic chuck is made up of: a chuck main body having electrodes; a chuck plate of a dielectric material and having a rib portion with which a peripheral edge portion of the substrate is capable of coming into surface contact, and a plurality of supporting portions which are vertically disposed at a predetermined distance from one another in an inner space enclosed by the rib portion; and a gas introduction means for introducing a predetermined gas into the inner space. When the substrate is held by the electrostatic chuck which is arranged to attract the substrate by the chuck plate and to form a gas atmosphere by supplying a predetermined gas into the inner space, a current value is monitored by causing an AC current to flow in a capacitance of the chuck plate through an AC power supply, a gas flow amount is monitored by causing the gas to flow through the gas introduction means, and a substrate state is managed based on a variation in at least one of the current value and the gas flow amount to prevent damages to the substrate.