Electrostatic Chuck Bias Compensation for Stable Plasma Clamping
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Solution Overview
Problem
Conventional substrate clamping systems in semiconductor manufacturing face challenges with maintaining consistent clamping during plasma processing, leading to potential substrate damage due to fluctuations in plasma potential and inadequate adjustment of clamping voltage, especially with high bias power applications.
Innovation Solution
A system comprising a plasma processing chamber with a substrate support assembly, a waveform generator, a power delivery line with a blocking capacitor, a clamping network, and a signal detection module, which delivers pulsed-voltage waveforms and adjusts the clamping voltage based on real-time detection of electrical signals to maintain a constant sheath voltage and ion energy distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed DC voltage is applied to the second electrode in the ESC to clamp the substrate, then the substrate is secured to the ESC, but the electrostatic force fluctuates with RF bias power changes leading to under or over clamping
Solution Approach 1:
The patent implements a feedback control system where the actual electrostatic clamping force is continuously monitored and compared to the target clamping force. The controller adjusts the DC voltage applied to the second electrode in real-time based on this feedback to maintain consistent clamping force despite variations in RF bias power. This resolves the contradiction by making the clamping system adaptive while maintaining stability.
Solution Approach 2:
The patent transitions from a static fixed DC voltage system to a dynamic system where the DC voltage is continuously adjusted based on operating conditions. The controller modifies the clamping voltage in response to RF bias power changes, making the system adaptable to different processing conditions while maintaining reliable substrate securing.
2Power
If large bias voltage in the kilovolt range is applied for high bias power, then ion energy for plasma processing is sufficient, but the fluctuation of self-bias voltage increases the risk of arcing or sudden de-clamping and breaking of the substrate
Solution Approach 1:
The patent employs feedback control to continuously monitor the self-bias voltage and adjust the DC clamping voltage to compensate for fluctuations. This prevents the voltage from exceeding safe thresholds that could cause arcing or substrate de-clamping, while still allowing high bias power to be applied for sufficient ion energy in plasma processing.
Solution Approach 2:
The patent applies a DC clamping voltage that creates an electrostatic holding force before plasma processing begins. This pre-established clamping force acts as a cushion against potential sudden de-clamping events caused by self-bias voltage fluctuations during high power operation, preventing substrate damage beforehand.
3Use of energy by moving object
If RF power is supplied to the first electrode in the ESC to bias the substrate, then ion bombardment energy for plasma processes is achieved, but the electrostatic force affecting substrate clamping leads to under or over clamping
Solution Approach 1:
The patent implements feedback control that monitors the relationship between RF bias power and electrostatic clamping force. The controller adjusts the DC voltage to the second electrode to maintain consistent clamping despite the non-linear interaction between RF power and electrostatic force, ensuring manufacturing precision while achieving necessary ion bombardment energy.
Solution Approach 2:
The patent dynamically changes the DC voltage parameter applied to the second electrode based on the RF power level. By adjusting this parameter in response to RF power changes, the system maintains consistent clamping force while allowing the RF power to provide sufficient ion bombardment energy for plasma processes.
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 approach ensures reliable substrate biasing and clamping, preventing substrate damage by accounting for plasma potential fluctuations and maintaining consistent ion energy distribution, thereby improving plasma processing results.
Implementation Method 1
the first power delivery line comprises a blocking capacitor
Implementation Method 2
a fixed DC voltage to a second electrode embedded in the ESC to establish an electric field between the ESC and the substrate. The electric field induces opposite polarity charges to accumulate on the substrate and the second electrode, respectively. The electrostatic attractive force between the oppositely polarized charges pulls the substrate toward the ESC
Implementation Method 3
The electrostatic attractive force between the oppositely polarized charges pulls the substrate toward the ESC to secure the substrate
Implementation Method 4
Non-linear, diode-like nature of the plasma sheath results in rectification of the applied RF field, such that a direct-current (DC) voltage drop, or self-bias, appears between the substrate and the plasma
Implementation Method 5
Ion bombardment is often used as a source of activation energy for chemical and physical processes in plasma etch and plasma enhanced chemical vapor deposition (PECVD) processes for processing a semiconductor substrate. High energy ions accelerated by plasma sheath are also highly directional and can be used for etching high aspect ratio features
Data Source
AI summary
Embodiments of the present disclosure relate to a system for pulsed direct-current (DC) biasing and clamping a substrate. In one embodiment, the system includes a plasma chamber having an electrostatic chuck (ESC) for supporting a substrate. An electrode is embedded in the ESC and is electrically coupled to a biasing and clamping network. The biasing and clamping network includes at least a shaped DC pulse voltage source and a clamping network. The clamping network includes a DC source and a diode, and a resistor. The shaped DC pulse voltage source and the clamping network are connected in parallel. The biasing and clamping network automatically maintains a substantially constant clamping voltage, which is a voltage drop across the electrode and the substrate when the substrate is biased with pulsed DC voltage, leading to improved clamping of the substrate.