Pulsed Power Supply for Substrate Processing
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Solution Overview
Problem
Existing substrate processing methods using parallel-plate type apparatuses face challenges in suppressing charging damage and local abnormal etching (notching) during plasma processing, particularly when processing deep or complex shapes on insulating films, due to uneven ion and electron distribution.
Innovation Solution
A substrate processing method employing a pulsed power supply that applies a combination of negative and positive voltage pulses, with a floating potential interval between them, superimposed on an RF voltage, to control ion energy and reduce charging by generating anisotropic electrons, thereby improving processing accuracy and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a negative voltage pulse is applied to suppress charging damage, then charging damage is reduced, but ion energy distribution becomes uneven causing local abnormal etching
Solution Approach 1:
The patent applies periodic voltage pulses with alternating polarities (negative and positive) to the substrate electrode. The negative pulses suppress charging damage by neutralizing accumulated charges, while the positive pulses restore ion energy distribution uniformity. This periodic switching resolves the contradiction by sequentially addressing both harmful effects rather than attempting to eliminate them simultaneously.
Solution Approach 2:
The patent dynamically changes voltage parameters including amplitude, pulse width, and duty cycle to optimize the balance between charging suppression and etching uniformity. By adjusting these parameters, the system can adapt to different processing conditions and substrate types, resolving the contradiction through parameter optimization rather than structural modification.
2Productivity
If pulse width is increased to improve processing rate, then productivity increases, but charging damage worsens
Solution Approach 1:
The patent uses periodic voltage pulses where the duty cycle (ratio of pulse width to total period) is optimized to balance processing rate and charging damage. By maintaining appropriate pulse frequencies and duty cycles, the system achieves high processing rates through extended effective processing time while preventing charge accumulation that causes damage.
3Manufacturing precision
If positive voltage pulse is applied to restore ion energy, then etching uniformity improves, but electron current increases causing charging damage
Solution Approach 1:
The patent employs periodic alternation between negative and positive voltage pulses. The positive pulses restore ion energy distribution for uniform etching, while the subsequent negative pulses suppress charging damage caused by increased electron current. This temporal separation of functions resolves the contradiction by addressing each effect at different time intervals.
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 method effectively narrows the distribution of ion energy, reduces charging, and enhances processing accuracy by controlling the mean incident energy and electron current, resulting in improved substrate processing with reduced notching and increased processing rate.
Implementation Method 1
a parallel-plate type substrate processing apparatus generates plasma by applying an RF (radio-frequency) voltage to one of a pair of electrodes
Implementation Method 2
The RF power supply applies an RF voltage having a frequency of 50 MHz or higher to the second electrode
Implementation Method 3
apply a negative voltage pulse from a pulsed power supply... apply a positive voltage pulse... control ion energy and reduce charging
Data Source
AI summary
A substrate processing method using a substrate processing apparatus includes a first step and a second step. The first step is to apply a negative voltage pulse from a pulsed power supply to be included in the apparatus. The second step is to apply floating potential for an interval of time between the negative voltage pulse and a positive voltage pulse from the pulsed power supply subsequent to the negative voltage pulse. In addition, the apparatus includes a chamber, a first electrode, a second electrode, an RF power supply, and the pulsed power supply. The second electrode is provided so that the second electrode faces the first electrode to hold a substrate. The RF power supply applies an RF voltage having a frequency of 50 MHz or higher to the second electrode. The pulsed power supply repeatedly applies a voltage waveform with the RF voltage to the second electrode.