Electrostatic Chuck Voltage Waveform for Substrate Warpage Control
Solution Overview
Problem
Semiconductor fabrication devices face substrate warpage and cracking due to thermal stress during electrostatic clamping, as existing methods either prolong clamping voltage switching to reduce warpage or shorten it, leading to steeper temperature rise and increased warpage.
Innovation Solution
An electrostatic chuck system with a controller that applies a voltage waveform combining a stepwise, rectilinear, or quadratic first waveform with a periodic second waveform, such as rectangular, triangular, saw-tooth, or sine waves, to smoothly change substrate temperature and relieve thermal stress, minimizing warpage and cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the clamping voltage is switched in a stepwise manner to reduce substrate temperature rise rate, then substrate warpage is reduced, but the substrate remains tightly clamped for extended periods preventing thermal stress relief
Solution Approach 1:
The patent applies periodic voltage interruptions during the electrostatic clamping process. Instead of maintaining continuous clamping voltage, the system periodically interrupts the voltage supply, creating cycles of clamping and release. This periodic action allows the substrate to expand and contract freely during voltage interruption periods, enabling thermal stress relief while still achieving effective clamping during voltage application periods. The technique resolves the contradiction by preventing the substrate from remaining tightly clamped for extended continuous periods.
Solution Approach 2:
The patent dynamically adjusts the clamping voltage waveform from a static stepwise approach to a time-varying periodic waveform. The voltage is modulated over time with specific duty cycles and frequencies, transforming the clamping process from a steady-state condition to a dynamic process. This dynamic approach allows the system to alternate between clamping and release states, enabling both warpage control and thermal stress relief.
2Productivity
If the clamping voltage switching time is shortened to improve processing efficiency, then productivity increases, but the substrate temperature rise rate becomes steeper increasing warpage
Solution Approach 1:
The periodic voltage interruption technique allows for faster overall processing by creating efficient cycles of clamping and release. During each cycle, the substrate is quickly clamped during voltage application and quickly released during voltage interruption, enabling rapid temperature adjustment without sustained steep temperature gradients. This periodic approach achieves both speed and temperature control.
Solution Approach 2:
The patent applies voltage interruptions at strategically timed moments during the heating process, before excessive temperature gradients develop. By preemptively creating release periods during early heating stages, the system prevents steep temperature rises and associated warpage before they occur, rather than attempting to correct them afterward.
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
The synergistic effect of the combined waveforms allows for effective stress relief and reduced substrate warpage and cracking, maintaining substrate stability during processing.
Implementation Method 1
a chuck body (1) having a clamping face (4) for electrostatically clamping a substrate (5)
Implementation Method 2
a temperature regulating portion (3) regulating the temperature of the substrate (5) to maintain it at a predetermined level
Data Source
AI summary
An electrostatic chuck system comprising a chuck body 1 having a clamping face 4 for electrostatically clamping a substrate 5, an electrode portion 2 generating a clamping force on the clamping face 4, a temperature-regulating portion 3 regulating the temperature of the substrate 5 to maintain it at a predetermined level, and a controller 10 controlling the voltage applied to the electrode portion 2, wherein, prior to completion of the electrostatic clamping of the substrate 5 to the chuck body 1, a voltage waveform obtained by superimposing a first waveform, which changes in a stepwise, rectilinear, or quadratic manner between a first level and a second level having a larger absolute value than the first level, and a periodic second waveform, which may be any of a rectangular wave, a triangular wave, a saw-tooth wave, or a sine wave, is applied by the controller 10 to the electrode portion 2.