Substrate Processing Apparatus with High-Frequency Pulse Voltage
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Solution Overview
Problem
In parallel-plate substrate processing, applying a positive voltage in a pulse state does not necessarily result in an effective process due to charge-up damage and local abnormal etching, such as notching, especially when processing deep or complex shapes on insulating films.
Innovation Solution
A substrate processing apparatus that includes a chamber with a first and second electrode, where an RF power supply applies a 50 MHz or higher frequency RF voltage to the second electrode, and a pulse power supply superposes a combined voltage waveform with a negative voltage pulse and a positive voltage pulse, the delay time of which is 50 nano-seconds or less, to control ion energy and reduce charge-up by applying a positive voltage pulse in addition to the negative voltage pulse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a positive voltage in a pulse state is applied to suppress charge up damage and local abnormal etching, then charge up damage and notching are reduced, but the processing effectiveness deteriorates because it is not necessarily possible to perform an effective process
Solution Approach 1:
The patent applies periodic pulse voltage waveforms with specific duty ratios (positive voltage applied for a portion of the cycle, e.g., 10-90% duty ratio) to achieve both charge-up suppression and effective processing. The periodic application of positive voltage pulses neutralizes accumulated negative charge while maintaining processing effectiveness through controlled timing and duration.
Solution Approach 2:
The patent changes voltage parameters by applying positive voltage pulses with specific amplitude ranges (e.g., 10-1000 V) and duty ratios (10-90%) instead of continuous or simple pulsed voltage. This parameter optimization enables simultaneous achievement of charge-up damage suppression and effective etching processing.
2Reliability
If a positive voltage pulse is applied to reduce charge-up, then charge-up is reduced, but processing precision may deteriorate due to potential etching stoppages and loss of anisotropy
Solution Approach 1:
The periodic pulse waveform with optimized duty ratio ensures that positive voltage is applied for sufficient duration to reduce charge-up but not so long as to cause etching stoppages. The cyclic application maintains ion flux and anisotropy while periodically neutralizing charge accumulation.
Solution Approach 2:
The patent dynamically adjusts the voltage waveform parameters including pulse width, amplitude, and duty ratio to maintain optimal balance between charge-up suppression and etching precision. The dynamic control prevents etching stoppages while preserving anisotropic etching characteristics.
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 allows for high-accuracy processing with reduced charge-up and improved anisotropy, enabling the formation of deep shapes and complex features without notching, by controlling the average incident energy and narrowing the energy distribution of ions, thus enhancing processing precision and preventing etching stoppages.
Implementation Method 1
plasma is generated by applying RF (radio frequency) to one of a pair of electrodes
Implementation Method 2
plasma is generated by applying RF (radio frequency) to one of a pair of electrodes
Implementation Method 3
a voltage waveform including a negative voltage pulse and a positive voltage pulse... to control ion energy
Implementation Method 4
to suppress a charge up damage and a local abnormal etching (notching)
Data Source
AI summary
In one embodiment, a substrate processing apparatus, includes: a chamber; a first electrode disposed in the chamber; a second electrode disposed in the chamber to face the first electrode, and to hold a substrate; an RF power supply to apply an RF voltage with a frequency of 50 MHz or more to the second electrode; and a pulse power supply to repeatedly apply a voltage waveform including a negative voltage pulse and a positive voltage pulse of which delay time from the negative voltage pulse is 50 nano-seconds or less to the second electrode while superposing on the RF voltage.