JP-2026076197-A - High-frequency (RF) pulse impedance tuning using multiplier modes

Abstract

[Problem] A method for reducing RF pulse reflection is provided. [Solution] In some embodiments, a method for processing a substrate in a plasma substrate processing system using multilevel pulsed RF power includes the steps of: receiving a processing recipe for processing the substrate, which includes a plurality of pulsed RF power waveforms from a plurality of RF generators; generating a transistor-to-transistor logic (TTL) signal having a fundamental frequency and a first duty cycle using a master RF generator; setting multipliers for each RF generator; dividing the first duty cycle into high-level intervals and low-level intervals; determining a frequency command set for each RF generator and transmitting the frequency command set to each RF generator, wherein the frequency command set includes frequency setting points for each RF generator; and providing a plurality of pulsed RF power waveforms from the plurality of RF generators to a processing chamber. [Selection Diagram] Figure 1

Inventors

• 川崎 勝正
• フィ ジャスティン
• ラマスワミ カーティク
• ショージ セルジオ フクダ
• 清水 大亮

Assignees

• アプライド マテリアルズ インコーポレイテッド

Dates

Publication Date

20260511

Application Date

20260112

Priority Date

20180830

Claims (15)

1. A method for processing a substrate in a plasma substrate processing system using multilevel pulsed RF power, A step of receiving a processing recipe for processing a substrate, which includes multiple pulse RF power waveforms from multiple RF generators, wherein the multiple RF generators include a master RF generator and one or more slave RF generators. A process of generating a transistor-to-transistor logic (TTL) signal having a fundamental frequency and a first duty cycle using a master RF generator, A step of setting a multiplier for each RF generator, wherein the multiplier is a multiple of the fundamental frequency, A process of dividing the first duty cycle into high-level intervals and low-level intervals, A step of determining a frequency command set for each RF generator and transmitting the frequency command set to each RF generator, wherein the frequency command set includes a frequency setting point for each RF generator. A method comprising the step of providing a plurality of pulsed RF power waveforms from a plurality of RF generators to a processing chamber in accordance with a set of frequency commands transmitted to each RF generator.
2. The process of determining the frequency command set is: A process for calculating high average impedance values over high-level intervals and low average impedance values over low-level intervals, A process of calculating the target impedance based on high average impedance values and low average impedance values, The method according to claim 1, comprising the step of tuning one or more RF matching networks to a target impedance.
3. The method according to claim 2, further comprising the step of adjusting the frequency or power provided by at least one of a plurality of RF generators to reduce at least one of a high average impedance value and a low average impedance value.
4. The method according to claim 3, wherein the step of tuning one or more RF matching networks to a target impedance includes the step of tuning variable matching components located within one or more RF matching networks to a target impedance.
5. The method according to claim 4, wherein the variable matching component for tuning to the target impedance includes at least one of a variable capacitor or an inductor.
6. The method according to claim 1, wherein the frequency command set is determined by the RF matching network associated with each RF generator.
7. The method according to claim 6, wherein the frequency command set is transmitted to each RF generator via a high-speed link cable that directly and communicatively connects the RF matching network and each RF generator.
8. The method according to claim 6, wherein the frequency command set is transmitted indirectly to each RF generator by the RF matching network via a controller communicatively connected to the RF matching network and each RF generator.
9. The method according to any one of claims 1 to 8, wherein the high-level interval is at least one of the following: the duration of the detected rising and falling edges of the TTL signal, or the low-level interval is at least one of the duration of the detected falling and rising edges of the TTL signal.
10. The method according to any one of claims 1 to 8, further comprising the step of receiving a timing signal from a master RF generator and synchronizing multiple RF power waveforms from one or more slave RF generators.
11. The method according to any one of claims 1 to 8, wherein the multiplier for each RF generator can be set independently.
12. The method according to any one of claims 1 to 8, wherein at least one of the multiple RF power waveforms is a triple-level pulsed (TLP) waveform pulsed at multiple power levels.
13. A non-temporary computer-readable medium containing instructions that, when executed, cause a method to operate a plasma substrate processing system, A computer-readable medium wherein the method is as described in any one of claims 1 to 8.
14. A substrate processing system, Multiple RF generators configured to provide multiple RF power waveforms to a processing chamber during a first duty cycle, comprising a master RF generator and one or more slave RF generators, A pulse controller connected to multiple RF generators, A matching network connected to each of a plurality of RF generators, processing chambers, and pulse controllers, A measuring device configured to measure reflected power or impedance for multiple RF power waveforms, A matching network comprising at least one variable matching component, The pulse controller or at least one of the at least one matching network is We received a processing recipe for processing the circuit board. Set a multiplier for at least one of the multiple RF generators, which is a multiple of the fundamental frequency of the TTL signal generated by the master RF generator. The first duty cycle of the TTL signal is divided into high-level intervals and low-level intervals. A frequency command set for each RF generator, which includes a frequency setting point for each RF generator, is determined and the frequency command set is transmitted to each RF generator. A substrate processing system configured to provide RF power waveforms from each RF generator to the processing chamber according to a set of frequency commands transmitted to each RF generator.
15. The process of determining the frequency command set for each RF generator is as follows: The process of calculating a high average impedance value over a high-level interval, The process of calculating a low average impedance value over low-level intervals, The substrate processing system according to claim 14, comprising the step of calculating a target impedance based on a high average impedance value and a low average impedance value.

Description

field Embodiments of this disclosure generally relate to RF power supply methods used for processing substrates. background In conventional radio frequency (RF) plasma processing (such as RF plasma processing used in the manufacturing stages of many semiconductor devices), RF energy may be supplied to the substrate processing chamber via an RF energy source. RF energy may be generated and supplied in a continuous wave or pulsed wave manner. Due to mismatch between the impedance of the RF energy source and the plasma formed in the processing chamber, RF energy is reflected back to the RF energy source, resulting in inefficient use and waste of RF energy, potential damage to the processing chamber or RF energy source, and potential inconsistency/non-reproducibility issues with substrate processing. Thus, RF energy is often coupled to the plasma in the processing chamber via a fixed or tunable matching network. This matching network operates to minimize reflected RF energy by more precisely matching the plasma impedance to the impedance of the RF energy source. The matching network attempts to maximize the amount of energy coupled to the plasma by efficiently coupling the output of the RF source to the plasma (e.g., called RF power supply tuning). Therefore, the matching network attempts to adjust the total impedance (i.e., plasma impedance + chamber impedance + matching network impedance) to be the same as the output impedance of the RF power supply. In some embodiments, the RF energy source may also be configured to support impedance matching by enabling frequency tuning or adjustment of the frequency of the RF energy supplied by the RF energy source. In processing chambers using multiple separate RF power signals pulsed at multiple power levels, synchronous RF pulses are typically used. However, the inventors have often observed that impedance tuning becomes difficult with various RF pulse schemes due to numerous impedance changes. That is, the matching network and/or RF generator cannot properly tune to the reflected power as the reflected power changes. Therefore, the inventors provide an improved method and apparatus for RF pulse tuning that uses one or more variable frequency generators in addition to variable capacitors/inductors, thereby beneficially minimizing RF pulse reflections in the processing chambers. These processing chambers utilize multiple separate RF power signals pulsed at multiple power levels during a single duty cycle. This specification provides methods and systems for reducing RF pulse reflection. In some embodiments, a method for processing a substrate in a plasma substrate processing system using multilevel pulsed RF power includes the steps of: receiving a processing recipe for processing a substrate, which includes a plurality of pulsed RF power waveforms from a plurality of RF generators, wherein the plurality of RF generators include a master RF generator and one or more slave RF generators; generating a transistor-to-transistor logic (TTL) signal having a fundamental frequency and a first duty cycle using the master RF generator; setting a multiplier for each RF generator, wherein the multiplier is a multiple of the fundamental frequency; dividing the first duty cycle into high-level and low-level intervals; determining a frequency command set for each RF generator and transmitting the frequency command set to each RF generator, wherein the frequency command set includes frequency setting points for each RF generator; and providing a plurality of pulsed RF power waveforms from the plurality of RF generators to a processing chamber according to the frequency command set transmitted to each RF generator. In some embodiments, instructions stored in a non-temporary computer-readable medium cause a method to operate a plasma substrate processing system when executed. This method includes the steps of: receiving a processing recipe for processing a substrate, including multiple pulsed RF power waveforms from multiple RF generators, wherein the multiple RF generators include a master RF generator and one or more slave RF generators; generating a TTL signal having a fundamental frequency and a first duty cycle using the master RF generator; setting a multiplier for each RF generator, wherein the multiplier is a multiple of the fundamental frequency; dividing the first duty cycle into high-level and low-level intervals; determining a frequency command set for each RF generator and transmitting the frequency command set to each RF generator, wherein the frequency command set includes frequency setting points for each RF generator; and providing multiple pulsed RF power waveforms from the multiple RF generators to a processing chamber according to the frequency command set transmitted to each RF generator. In some embodiments, the substrate processing system comprises a plurality of RF generators configured to supply a plurality of RF power waveforms to a processing chamber during a fir