JP-7857345-B2 - Active control of radial etching uniformity

JP7857345B2JP 7857345 B2JP7857345 B2JP 7857345B2JP-7857345-B2

Inventors

マラクタノブ・アレクセイ
コザケビッチ・フェリックス・レイ
ホランド・ジョン
ジ・ビン
ルッケシ・ケネス

Assignees

ラムリサーチコーポレーション

Dates

Publication Date: 20260512
Application Date: 20240625
Priority Date: 20180618

Claims (20)

A controller for controlling radial etching uniformity, It is a processor, Control the first RF power supply to generate a first radio frequency (RF) signal having a fundamental frequency and a first phase. The second RF power supply is controlled to generate a second RF signal having the (n-1)th harmonic frequency and a second phase, respectively, based on the fundamental frequency and the first phase, where n is an integer greater than 2. A processor configured to control a third RF power supply to generate a third RF signal having an nth harmonic frequency and a third phase based on the fundamental frequency and the first phase, respectively; the first, second, and third RF signals are generated to be supplied to an RF matcher, the first RF signal is modified by the RF matcher to provide a first modification signal, the second RF signal is modified by the RF matcher to provide a second modification signal, the third RF signal is modified by the RF matcher to provide a third modification signal, the first, second, and third modification signals are generated from the first, second, and third signals by matching the impedance of a load coupled to the output of the RF matcher with the impedance of a source coupled to the input of the RF matcher, the first, second, and third modification signals are combined within the RF matcher to output a combined RF signal, the combined RF signal is output to be supplied to electrodes in a plasma chamber to control the radial etching uniformity across the surface of the substrate; A controller comprising a memory device coupled to the aforementioned processor.
A controller according to claim 1, A controller in which the first RF signal is generated to be supplied to the first input of the RF matcher, the second RF signal is generated to be supplied to the second input of the RF matcher, and the third RF signal is generated to be supplied to the third input of the RF matcher.
A controller according to claim 1, The aforementioned processor, The first measured value of the fundamental frequency of the first RF signal and the second measured value of the (n-1)th harmonic frequency of the second RF signal are received. Determine whether the difference between the first measurement and the second measurement falls within a first predetermined range from a first predetermined frequency difference. A controller configured to control the first RF power supply or the second RF power supply until the difference between the first measured value and the second measured value falls within a first predetermined range from a first predetermined frequency difference.
A controller according to claim 3, The aforementioned processor, The third measurement of the nth harmonic frequency of the third RF signal is received, Determine whether the difference between the first measurement and the third measurement falls within a second predetermined range from a second predetermined frequency difference. A controller configured to control the first RF power supply or the third RF power supply until the difference between the first measured value and the third measured value falls within a second predetermined range from a second predetermined frequency difference.
A controller according to claim 1, The aforementioned processor, The first measured value of the first phase of the first RF signal and the second measured value of the second phase of the second RF signal are received. Determine whether the difference between the first measurement and the second measurement falls within a first predetermined range from a first predetermined phase difference. A controller configured to control the first RF power supply or the second RF power supply until the difference between the first measured value and the second measured value falls within a first predetermined range from a first predetermined phase difference.
A controller according to claim 5, The aforementioned processor, The third measured value of the third phase of the third RF signal is received. Determine whether the difference between the first measurement and the third measurement falls within a second predetermined range from a second predetermined phase difference. A controller configured to control the first RF power supply or the third RF power supply until the difference between the first measured value and the third measured value falls within a second predetermined range from a second predetermined phase difference.
A controller according to claim 1, The aforementioned processor, The first measurement of the first parameter level of the first RF signal and the second measurement of the second parameter level of the second RF signal are received. Determine whether the difference between the first measurement and the second measurement falls within a first predetermined range from a first predetermined parameter level difference. A controller configured to control the first RF power supply or the second RF power supply until the difference between the first measured value and the second measured value falls within a first predetermined range from a first predetermined parameter level difference.
A controller according to claim 7, The aforementioned processor, The third measurement value of the third parameter level of the third RF signal is received. It is determined whether the difference between the first measurement and the third measurement falls within a second predetermined range from a second predetermined parameter level difference. A controller configured to control the first RF power supply or the third RF power supply until the difference between the first measured value and the third measured value falls within a second predetermined range from a second predetermined parameter level difference.
A method for controlling radial etching uniformity, Control the first RF power supply to generate a first radio frequency (RF) signal having a fundamental frequency and a first phase. A second RF power supply is controlled to generate a second RF signal having an (n-1)th harmonic frequency and a second phase, based on the fundamental frequency and the first phase, respectively, where n is an integer greater than 2. The system includes controlling a third RF power supply to generate a third RF signal having an nth harmonic frequency and a third phase, based on the fundamental frequency and the first phase, respectively. A method comprising: generating the first, second, and third RF signals for supply to an RF matcher; modifying the first RF signal by the RF matcher to provide a first modification signal; modifying the second RF signal by the RF matcher to provide a second modification signal; modifying the third RF signal by the RF matcher to provide a third modification signal; generating the first, second, and third modification signals from the first, second, and third signals by matching the impedance of a load coupled to the output of the RF matcher with the impedance of a source coupled to the input of the RF matcher; combining the first, second, and third modification signals within the RF matcher to output a combined RF signal; and outputting the combined RF signal to be supplied to electrodes in a plasma chamber to control the radial etching uniformity across the surface of the substrate.
The method according to claim 9, A method wherein the first RF signal is generated to be supplied to the first input of the RF matcher, the second RF signal is generated to be supplied to the second input of the RF matcher, and the third RF signal is generated to be supplied to the third input of the RF matcher.
The method according to claim 9, further, The first measured value of the fundamental frequency of the first RF signal and the second measured value of the (n-1)th harmonic frequency of the second RF signal are received. Determine whether the difference between the first measurement and the second measurement falls within a first predetermined range from a first predetermined frequency difference. A method comprising controlling the first RF power supply or the second RF power supply until the difference between the first measured value and the second measured value falls within a first predetermined range from a first predetermined frequency difference.
The method according to claim 11, further, The third measurement of the nth harmonic frequency of the third RF signal is received, Determine whether the difference between the first measurement and the third measurement falls within a second predetermined range from a second predetermined frequency difference. A method comprising controlling the first RF power supply or the third RF power supply until the difference between the first measured value and the third measured value falls within a second predetermined range from a second predetermined frequency difference.
The method according to claim 9, further, The first measured value of the first phase of the first RF signal and the second measured value of the second phase of the second RF signal are received. Determine whether the difference between the first measurement and the second measurement falls within a first predetermined range from a first predetermined phase difference. A method comprising controlling the first RF power supply or the second RF power supply until the difference between the first measured value and the second measured value falls within a first predetermined range from a first predetermined phase difference.
The method according to claim 13, further, The third measured value of the third phase of the third RF signal is received. Determine whether the difference between the first measurement and the third measurement falls within a second predetermined range from a second predetermined phase difference. A method comprising controlling the first RF power supply or the third RF power supply until the difference between the first measured value and the third measured value falls within a second predetermined range from a second predetermined phase difference.
The method according to claim 9, further, The first measurement of the first parameter level of the first RF signal and the second measurement of the second parameter level of the second RF signal are received. Determine whether the difference between the first measurement and the second measurement falls within a first predetermined range from a first predetermined parameter level difference. A method comprising controlling the first RF power supply or the second RF power supply until the difference between the first measured value and the second measured value falls within a first predetermined range from a first predetermined parameter level difference.
The method according to claim 15, further, The third measurement value of the third parameter level of the third RF signal is received. It is determined whether the difference between the first measurement and the third measurement falls within a second predetermined range from a second predetermined parameter level difference. A method comprising controlling the first RF power supply or the third RF power supply until the difference between the first measured value and the third measured value falls within a second predetermined range from a second predetermined parameter level difference.
A plasma system for controlling radial etching uniformity, An RF generator having a first radio frequency (RF) power supply, a second RF power supply, and a third RF power supply, An RF matching unit coupled to the RF generator and a plasma chamber coupled to the RF matching unit, including electrodes, It is a controller, The first RF power supply is controlled to generate a first RF signal having a fundamental frequency and a first phase, The second RF power supply is controlled to generate a second RF signal having an (n-1)th harmonic frequency and a second phase, based on the fundamental frequency and the first phase, respectively, where n is an integer greater than 2. A controller configured to control the third RF power supply to generate a third RF signal having an nth harmonic frequency and a third phase based on the fundamental frequency and the first phase, respectively, A plasma system comprising: the first, second, and third RF signals are generated for supply to the RF matcher, the RF matcher is configured to modify the first RF signal to provide a first correction signal, the second RF signal to provide a second correction signal, and the third RF signal to provide a third correction signal, the first, second, and third correction signals are generated from the first, second, and third signals by matching the impedance of a load coupled to the output of the RF matcher with the impedance of a source coupled to the input of the RF matcher, the RF matcher is configured to combine the first, second, and third correction signals to output a combined RF signal, and the RF matcher is configured to supply the combined RF signal to the electrodes of the plasma chamber to control the radial etching uniformity across the surface of the substrate.
A plasma system according to claim 17, A plasma system in which the first RF signal is generated to be supplied to the first input of the RF matcher, the second RF signal is generated to be supplied to the second input of the RF matcher, and the third RF signal is generated to be supplied to the third input of the RF matcher.
A plasma system according to claim 17, The controller is, The first measured value of the fundamental frequency of the first RF signal and the second measured value of the (n-1)th harmonic frequency of the second RF signal are received. Determine whether the difference between the first measurement and the second measurement falls within a first predetermined range from a first predetermined frequency difference. A plasma system configured to control the first RF power supply or the second RF power supply until the difference between the first measured value and the second measured value falls within a first predetermined range from a first predetermined frequency difference.
A plasma system according to claim 19, The controller is, The third measurement of the nth harmonic frequency of the third RF signal is received, Determine whether the difference between the first measurement and the third measurement falls within a second predetermined range from a second predetermined frequency difference. A plasma system configured to control the first RF power supply or the third RF power supply until the difference between the first measured value and the third measured value falls within a second predetermined range from a second predetermined frequency difference.

Description

This disclosure relates to a system and method for actively controlling radial etching uniformity. The background art provided herein is intended to provide a general overview of the background to this disclosure. The research of the inventors named herein, and other descriptions that may not have been considered prior art at the time of filing, within the scope described in this background art section, are not explicitly or implicitly considered prior art to this disclosure. A plasma apparatus generally includes a radio frequency (RF) generator, an impedance matching circuit, and a plasma chamber. The RF generator produces a radio frequency signal that is supplied to the impedance matching circuit. The impedance matching circuit receives the radio frequency signal, outputs it, and supplies the radio frequency signal to the plasma chamber. The wafer is processed in the plasma chamber by the plasma generated when the radio frequency signal is supplied along with the processing gas. For example, the wafer is etched in the plasma chamber according to the radio frequency signal. When etching a wafer, there is non-uniformity in the etching process. The embodiments described in this disclosure arise in connection therewith. Embodiments of this disclosure provide systems, apparatus, methods, and computer programs for actively controlling radial etching uniformity. It should be understood that these embodiments can be implemented in numerous ways, such as processes, apparatus, systems, devices, or methods, on computer-readable media. Several embodiments are described below. Radial etching uniformity occurs within plasma etchers, such as capacitively coupled plasma etchers using parallel plates. Localization of plasma non-uniformity at the center, mid-diameter, edges, or polar edges results in non-uniform etching rates across the wafer surface. Examples of etching rate non-uniformity include central peak non-uniformity, W-shaped non-uniformity, and M-shaped non-uniformity. Etching rate non-uniformity is observed at various radio frequency (RF) drive frequencies, processing gaps, and gas pressures. Due to its properties, the plasma generated within the plasma etcher produces multiple harmonics with respect to the RF drive frequency. Some of the higher-order harmonics generate standing waves within the plasma, which contribute to etching rate non-uniformity across the wafer surface. Because of these standing waves, it is difficult to increase radial etching uniformity by adjusting processing parameters such as the processing gap between the plasma etcher chuck and the upper electrode, the RF power ratio, the gas center weight delivery, and the pressure within the plasma etcher. In some embodiments, the systems and methods described herein provide active control of radial plasma uniformity through harmonic control. To provide active control, an additional RF power supply is provided within the RF generator, in addition to the main high-frequency RF power source. The additional RF power supply provides a high-RF harmonic power signal whose phase is adjustable or fixed relative to the fundamental frequency. The power magnitude, frequency, and phase of the high-RF harmonic power signal are optimized to reduce the effects of standing waves in the plasma on the wafer surface and increase radial etching uniformity. In various embodiments, the main high-frequency RF source supplies the fundamental drive frequency and the phase associated with the fundamental drive frequency to an additional RF source. The additional RF source generates RF power at twice, three times, four times, etc., the fundamental drive frequency, and its phase is adjustable relative to the phase associated with the fundamental drive frequency. By controlling the phase and power level of the additional RF source, the shape of the electromagnetic waves in the plasma, the radial shape of the plasma sheath, and the radial plasma density on the wafer surface are controlled to adjust the etching uniformity across the wafer surface, thereby increasing radial etching uniformity. In some embodiments, a method for controlling radial etching uniformity is described. The method includes generating a first RF signal having a fundamental frequency and a first phase. The method further includes generating a second RF signal having the (n-1)th harmonic frequency and a second phase, based on the fundamental frequency and the first phase, respectively. Note that n is an integer greater than or equal to 3. The method further includes generating a third RF signal having the nth harmonic frequency and a third phase, based on the fundamental frequency and the first phase, respectively. The method also includes receiving the first, second, and third RF signals by an RF matcher. The method includes outputting a modified RF signal to the electrodes of the plasma chamber by the RF matcher to control radial etching uniformity across the substrate surface during the etching operatio