KR102421082B1 - Rf tailored voltage on bias operation - Google Patents

Abstract

Methods, systems, and apparatus are provided for reducing particle generation on a showerhead during an ion bombardment process in a process chamber. First and second RF signals are supplied from an RF generator to an electrode embedded in a substrate support in the process chamber. The second RF signal is adjusted relative to the first RF signal in response to measurements of a first RF amplitude, a second RF amplitude, a first RF phase, and a second RF phase. Ion bombardment to the substrate is maximized and the amount of particles generated on the showerhead is minimized. The methods and systems described herein provide improved ion etching properties while reducing the amount of debris particles generated from the showerhead.

Description

RF TAILORED VOLTAGE ON BIAS OPERATION for bias operation

Embodiments of the present disclosure generally relate to methods and systems for controlling plasma in a process chamber.

Processing chambers are typically used to perform plasma processing of substrates, such as etching or deposition processes. During etching or deposition processes, particles may be deposited on the showerhead within the processing chamber. Material deposited on the showerhead can fall onto the underlying substrate or substrate support, contaminating the substrate and processing volume within the chamber.

Accordingly, a need exists to control and reduce particle generation in a processing chamber.

This disclosure generally describes methods, systems, and apparatus for reducing particle generation from a showerhead. In one example, a method of processing a substrate is provided. The method includes supplying a first radio frequency (RF) signal having a first frequency, a first amplitude, and a first phase. A first RF signal is supplied from an RF generator to an electrode embedded in a substrate support disposed within the process chamber. A second RF signal having a second frequency, a second amplitude, and a second phase is supplied from the RF generator to the electrode. The method further includes adjusting the second RF signal relative to the first RF signal to generate ions. Adjusting the second RF signal is performed in response to measurements of a first amplitude, a first phase, a second amplitude, and a second phase.

In another example, a system for processing a substrate is disclosed. The system includes a process chamber, wherein a substrate support is disposed within a processing volume of the process chamber. A showerhead is disposed over the substrate support within the processing volume of the process chamber. An electrode is embedded in the substrate support surface of the substrate support. The RF generator is configured to provide a first RF signal having a first frequency, a first amplitude, and a first phase, and a second RF signal having a second frequency, a second amplitude, and a second phase to the first electrode. 1 is coupled to the electrode. A controller is coupled to the RF generator to condition the second RF signal relative to the first RF signals in response to measurements of the first and second amplitudes and phases to generate ions for etching the substrate.

In another example, an apparatus for processing a substrate is disclosed. The apparatus includes a process chamber, wherein a substrate support is disposed within a processing volume of the process chamber. A showerhead is disposed over the substrate support within the processing volume of the process chamber. An electrode is embedded in the substrate support surface of the substrate support. The RF generator is configured to provide a first RF signal having a first frequency, a first amplitude, and a first phase, and a second RF signal having a second frequency, a second amplitude, and a second phase to the first electrode. 1 is coupled to the electrode. The controller adjusts the second RF signal relative to the first RF signal in response to measurements of the first and second amplitudes and phases to produce ions that are maximized proximate the substrate support surface and minimized proximate the showerhead. is connected to the RF generator.

In such a way that the above-mentioned features of the present disclosure may be understood in detail, a more specific description of the present disclosure, briefly summarized above, may be made with reference to embodiments, some of which may be understood in the accompanying drawings. are exemplified in It should be noted, however, that the appended drawings illustrate only exemplary embodiments and are not to be regarded as limiting in scope, as the present disclosure may admit to other equally effective embodiments.
1 shows a schematic diagram of a processing system according to an embodiment of the present disclosure;
2 illustrates calculated RF voltage shapes according to an embodiment of the present disclosure.
3 illustrates calculated RF voltage shapes according to an embodiment of the present disclosure.
4A illustrates a calculated DC self-bias voltage form in accordance with an embodiment of the present disclosure.
4B illustrates a calculated bulk plasma potential voltage shape in accordance with an embodiment of the present disclosure.
5 shows a schematic diagram of a processing system according to an embodiment of the present disclosure;
6 shows a flow diagram of an algorithm for identifying an RF tailored voltage by obtaining target RF voltage parameters, according to an embodiment of the present disclosure.
7 shows a block diagram of a frequency generator according to an embodiment of the present disclosure.
8 shows a block diagram of an amplitude and phase generator in accordance with an embodiment of the present disclosure.
9 shows a block diagram of an RF voltage monitor according to an embodiment of the present disclosure.
10 shows a block diagram of an IQ detector according to an embodiment of the present disclosure.
11 illustrates a method of controlling ion bombardment in a process chamber, according to an embodiment of the present disclosure.
To facilitate understanding, the same reference numbers have been used wherever possible to designate like elements common to the drawings. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

The present disclosure relates generally to plasma processing of substrates, such as etching and deposition of substrates. During etching and deposition processes, a capacitively coupled plasma is created between two electrodes, eg, a first electrode disposed within the substrate support and a second electrode disposed within the showerhead. The substrate support electrode is connected to the RF generator and the showerhead electrode is connected to an electrical ground or RF return. The plasma generated within the process chamber facilitates the etching of material from or deposition of material onto the substrate.

Aspects of the present disclosure relate to controlling the phase and voltage of an RF signal to simultaneously control deposition or etching to a substrate while reducing particle generation (eg, exfoliation) from a showerhead or other top electrode. Moreover, aspects herein relate to identifying phase differences between frequencies to facilitate an increase in deposition or etch to a substrate while reducing particle generation (eg, exfoliation) from a showerhead or other top electrode. will be.

Methods and systems are provided for reducing particle generation from a showerhead during an ion bombardment process in a process chamber. A first RF signal and a second RF signal are supplied from the RF generator to the first electrode embedded in the substrate support disposed in the process chamber. The second RF signal is a response to measured characteristics of the first and second RF signals, eg, a first amplitude and a first phase of the first RF signal, and a second amplitude and a second phase of the second RF signal. is adjusted for the first RF signal. In some embodiments that may be combined with one or more embodiments described above, ion bombardment to the substrate is increased and the amount of particles generated from the showerhead is reduced. The methods and systems herein enable etching through the utilization of ion bombardment while reducing the amount of debris particles generated from the showerhead. In addition, methods of increasing the accuracy of an RF voltage/current monitor by combining information from an RF match are discussed.

)에서 전극(105)에 전력을 인가한다. 전극(105) 및 샤워헤드(103)는, 용량성 결합된 플라즈마(106)의 생성을 용이하게 한다.1 shows a schematic diagram of a processing system 100 for performing a multi-frequency bias operation in a process chamber 101 . The processing system 100 includes a process chamber 101 coupled to a plurality of RF generators 108 via an n-frequency RF match 102 . The process chamber 101 includes a showerhead 103 disposed therein and connected to an electrical ground 107 (or RF return). The substrate support 104 is disposed opposite the showerhead 103 in the process chamber 101 . The substrate 137 is supported by a substrate support 104 . An electrode 105 is embedded in the substrate support 104 . Electrode 105 is connected to n-frequency RF match 102 . The n-frequency RF match 102 is, for each respective frequency f _i , the respective voltage V _i and the phase (

) to apply power to the electrode 105 . Electrodes 105 and showerhead 103 facilitate the creation of capacitively coupled plasma 106 .

According to one embodiment, which may be combined with one or more of the embodiments described above, a multi-frequency bias operation is performed in the process chamber 101 . During processing, electrode 105 is biased by multiple frequencies (eg, two different frequencies) via n-frequency RF match 102 , while showerhead 103 (eg, second electrode) is It is connected to electrical ground 107 to facilitate RF return. In one example, the frequencies applied by the n-frequency RF match 102 may be integer multiples of each other, eg, RF energy may be applied at both a first frequency of 13.56 MHz and a second frequency of 27.12 MHz. have. In some embodiments that may be combined with one or more embodiments described above, the first frequency and the second frequency are harmonic frequencies. In some embodiments that may be combined with one or more embodiments described above, the first frequency and the second frequency are adjacent harmonic frequencies.

Additionally, the surface area of the showerhead 103 is greater than the surface area of the substrate support 104 .

)에서,

에 의해 정의되는 기판(137)에 대한 이온 충격이 거의 최대가 되는 것으로 여겨진다. 동시에,

에 의해 정의되는, 플라즈마(106)의 접지 측(예컨대, 샤워헤드(103))에 대한 이온 충격이 거의 최소가 된다. 그에 따라 공정 챔버를 동작시키는 것은, 기판(137) 상의 식각을 최대화하면서 동시에 샤워헤드(103)로부터의 입자 생성을 최소화하는 것을 가능하게 한다.

을 거의 최대 값으로 조정하고

을 거의 최소 값으로 조정하는 것은, 이후 RF 맞춤조정된 전압으로 지칭될 것이다.Plasma 106 having a time averaged bulk plasma potential of V _pla , with a time averaged self-biased DC voltage of V _DC formed on the substrate support 104 when operating the process chamber 101 at multi-harmonic frequencies. is created When using dual frequency plasma generation, a specific phase value (

)at,

It is believed that the ion bombardment to the substrate 137, defined by <RTI ID=0.0> At the same time,

The ion bombardment to the ground side of the plasma 106 (eg, the showerhead 103 ), defined by , is nearly minimal. Operating the process chamber accordingly makes it possible to maximize the etch on the substrate 137 while minimizing particle generation from the showerhead 103 .

is adjusted to almost the maximum value and

Adjusting to near-minimum value will hereinafter be referred to as RF tuned voltage.

Electrode 105 connects via n-frequency RF match 102 to RF generators 108 ₁ , 108 ₂ , 108 _n at frequencies f ₁ , f ₂ , ... f _n , respectively. Connected. In general, the RF voltage at the substrate support 104 is expressed by the following equation (1):

(1)

(One)

는 각각

에서의 전압 및 위상이고, ω_i는 각주파수이다. 상응하는 RF 주기들을 유지하기 위해, 주파수 f_i는 기본 주파수 f₁의 i 번째 고조파 주파수이다:where V _i and

are each

is the voltage and phase at , and ω _i is the angular frequency. To keep the corresponding RF periods, the frequency f _i is the i th harmonic frequency of the fundamental frequency f ₁ :

, 여기서, i = 1, 2, ...... n (2)

, where i = 1, 2, ...... n (2)

Equation (2) facilitates the implementation of a timing clock in hardware.

In the process chamber 101 , a plasma 106 is generated with a time averaged bulk plasma potential of V _pla . As a result of the plasma generation in the process chamber 101 , a time-averaged self-bias DC voltage of V _DC is formed on the surface of the substrate 137 .

For the modeling example, equation (1) is further assumed in the form:

(3)

(3)

Also, when Equation (3) is limited to n = 2, it is as follows:

(4)

(4)

이 거의 최대 값이고

이 거의 최소 값인 RF 맞춤조정된 전압 조건을 만족시키기 위한 조정된 항들로서의 다른 고조파들을 주로 동작시키는 것이 유리한 것으로 여겨진다.In equation (3), the amplitude of the harmonic is normalized by the amplitude of the fundamental harmonic. As the harmonic order increases, the amplitude decreases, for example, the amplitude of the nth harmonic is 1/n of the fundamental harmonic. fundamental harmonics for processing, and

is almost the maximum

It is believed to be advantageous to primarily operate the other harmonics as tuned terms to satisfy this near-minimum RF tuned voltage condition.

In a dual frequency system, for example, when f ₁ = 13.56 MHz and f ₂ = 27.12 MHz, the phase difference between the two frequencies is defined by:

(5)

(5)

= 0과 함께 도 1의 기하학적 구조에 자기-일관적 플라즈마 모델링을 적용할 때, 도 2 및 도 3에서의 정규화된 시간의 함수들로서

= 0°, 90°, 180°, 270°에 대한 전압 파형 결과들이 획득된다.2 and 3 illustrate calculated RF voltage shapes according to an example. V ₁ = 200 V and

When applying self-consistent plasma modeling to the geometry of Fig. 1 with = 0, as normalized functions of time in Figs.

= 0°, 90°, 180°, 270° voltage waveform results are obtained.

의 함수로서 도시된다. 계산된 V_pla는 도 4b에서

의 함수로서 도시된다. 도 4a 및 도 4b에 예시된 바와 같이, 약

= 100°에서,

의 최소치는 약 60 V이고,

의 최대치는 약 360 V이다.4A illustrates a calculated DC self-bias voltage form according to an example. The calculated V _DC formed on the substrate support 104 illustrated in FIG. 1 is shown in FIG. 4A .

is shown as a function of The calculated V _pla is in FIG. 4b

is shown as a function of 4A and 4B , about

= at 100°,

The minimum of is about 60 V,

The maximum is about 360 V.

및

로 주어지므로,

= 100°에서의 플라즈마 처리는, 샤워헤드(103)에 대해 거의 최소의 이온 충격을 제공하여 그에 따라 샤워헤드(103)로부터의 입자 생성을 감소시키고, 기판 지지부(104) 상의 기판(137)에 대해 거의 최대의 충격을 제공하여 기판(137) 상에서의 이온 식각을 향상시킨다. 다시 말해서,

= 100°에서 동작시키는 것은, 기판(137) 상에서의 식각률을 최대화하면서 동시에 샤워헤드(103)로부터의 입자 생성을 최소화한다. 따라서, 이중 주파수 플라즈마 처리 동작 동안 위상차(

)를 변화시킴으로써 샤워헤드(103)로부터의 입자 생성이 최소화된다.Ion bombardment voltages for electrode 105 and showerhead 103 are respectively

and

Since it is given as

Plasma treatment at = 100° provides substantially minimal ion bombardment to the showerhead 103 thereby reducing particle generation from the showerhead 103 and to the substrate 137 on the substrate support 104 . Provides nearly maximum impact to the substrate 137 to enhance ion etching on the substrate 137 . In other words,

Operating at = 100° minimizes particle generation from the showerhead 103 while maximizing the etch rate on the substrate 137 . Therefore, during the dual frequency plasma processing operation, the phase difference (

), particle generation from the showerhead 103 is minimized.

It is contemplated that the plasma treatment may occur with an n-frequency RF match 102 using more than two different frequencies or with a second frequency that is an integer multiple of a first frequency, where the integer multiple is greater than one. For example, in Equation (4), the higher-order harmonic f ₂ may be replaced by the third harmonic of f ₁ which is 13.56 MHz (ie, f ₂ = 40.68 MHz).

5 shows a schematic diagram of a processing system 500 in accordance with an embodiment of the present disclosure that may be combined with one or more embodiments described above. The processing system 500 is similar to the processing system 100, but with a single n-frequency generator 508, an n-frequency RF match 502 coupled to and downstream of the n-frequency RF generator 508, and n - a voltage monitor 509 coupled to and downstream of the frequency RF match 502 . Although a single RF generator 508 is shown, it is contemplated that multiple RF generators may be used in the processing system 500 .

To enable more precise control and adjustment of process parameters, the voltage monitor 509 detects a voltage downstream of the n-frequency RF match 502 , which is determined by the geometry of the process chamber 501 . It corresponds to the voltage applied to the electrode 105 by the determined linear relationship (described later). Detecting the voltage downstream of the n-frequency RF match 502 provides a more accurate indication of conditions in the process chamber 501 , thus improving the adjustments made to the process parameters.

To facilitate process control, n-frequency RF generator 508 receives a signal from voltage monitor 509 via connection 510 . In response, RF generator 508 generates RF power signals at respective frequencies to satisfy RF tuned voltage condition operation at electrodes 105 and 103 . The n-frequency RF generator 508 may also receive a signal from the RF match 502 via connection 512 .

, i = 1, 2, ... n)을 활용하며, 이들은 기판 지지부(104)에서 정의된다. 그러나, 처리 시스템(500)에서, RF 전압들 및 위상들은 V_im 및

(i = 1, 2, ... n)과 같이 포스트-매치(즉, RF 매치(502)의 하류)여야 한다. 그러므로, 수학식 (1)에서의 도출된 값들 V_i 및

는 V_im 및

으로서 정의되는 포스트 RF 매치(502) 값들로 변환되며, 이는, 다음의 변환 행렬에 의해 계산된다:The determination of the phase and amplitude adjustment, as described above, is determined by the parameters (V _i and

, i = 1, 2, ... n), which are defined in the substrate support 104 . However, in processing system 500 , the RF voltages and phases are V _im and

It must be a post-match (ie downstream of the RF match 502 ), such as (i = 1, 2, ... n). Therefore, the derived values V _i in equation (1) and

is V _im and

are transformed into post RF match 502 values defined as

(6)

(6)

Here, all values are defined as complex numbers. Therefore, the values in Equation (1) are converted to the following form:

(7)

(7)

는 기판 지지부(104)에서 정의되고, 예컨대, 도 2, 도 3, 도 4a, 및 도 4b에 예시된 모델링에 기반하여 계산된다. ABCD 행렬은, 공정 챔버(501)의 기하학적 구조, 및 더 구체적으로는, 일련의 송신 라인들 및 커패시터들과 인덕터들의 일부 조합으로부터 계산될 수 있다.

은 임의성을 갖는다는 것이 유의된다. 따라서,

은 일반성을 잃지 않으면서

= 0으로서 정의될 수 있다. 동작 동안, RF 전압 파라미터들(V_i 및

)의 포스트 RF 매치(502)가 n-주파수 RF 전압 모니터(509)에 의해 측정되어, V_ime 및

로서 측정된 값들이 표시된다. RF 전압 파라미터들의 실험적 결정은, RF 맞춤조정된 전압의 결정을 가능하게 한다.

is defined in the substrate support 104 , and is calculated based on the modeling illustrated in FIGS. 2 , 3 , 4A, and 4B , for example. The ABCD matrix may be calculated from the geometry of the process chamber 501 and, more specifically, from a series of transmission lines and some combination of capacitors and inductors.

It is noted that has randomness. therefore,

without losing generality.

= 0. During operation, the RF voltage parameters (V _i and

) is measured by an n-frequency RF voltage monitor 509, V _ime and

The measured values are displayed as . Experimental determination of RF voltage parameters enables determination of RF tuned voltage.

)을 획득함으로써 RF 맞춤조정된 전압을 식별하기 위한 알고리즘의 흐름도를 도시한다. 일부 실시예들에서, V_im 및

은 사용자 정의 목표 파라미터들이다. 다른 실시예들에서, V_im 및

은 제2 RF 신호의 측정된 파라미터들이다. 동작(620) 동안, 실험적 파라미터들(V_ime 및

)은 n-주파수 RF 전압 모니터(509)에 의해 측정된다. 동작(621) 동안, 측정된 실험적 파라미터들(V_ime 및

)이 수학식들 (8) 및 (9)의 조건들을 만족시키는지 여부가 결정된다:6 shows the target RF voltage parameters (V _im and

) shows a flowchart of an algorithm for identifying an RF tuned voltage by obtaining In some embodiments, V _im and

are user-defined target parameters. In other embodiments, V _im and

are the measured parameters of the second RF signal. During operation 620, the experimental parameters V _ime and

) is measured by an n-frequency RF voltage monitor 509 . During operation 621, the measured experimental parameters (V _ime and

It is determined whether ) satisfies the conditions of equations (8) and (9):

(8)

(8)

(9)

(9)

)이 사용자 정의 공차 내에서 수학식들 (8) 및 (9)를 만족시키는 경우, n-주파수 RF 발생기(508) 상에서 어떠한 조정들도 수행되지 않는다. 사용자 정의 공차는 전형적으로 경험적이다. 진폭 비(수학식 (8))의 사용자 정의 공차는, 약 5 퍼센트, 예컨대, 약 3 퍼센트 내지 약 7 퍼센트, 이를테면, 약 4 퍼센트 내지 약 6 퍼센트이다. 상대각(수학식 (9))에 대한 사용자 정의 공차는, 약 3 도 내지 약 8 도, 예컨대, 약 4 도 내지 약 6 도이다. 그러나, 동작(621)의 알고리즘이 V_ime 및

의 측정된 값들에 의해 만족되지 않는 경우, 동작(622)에 예시된 바와 같이, 마이크로 제어 유닛(MCU) 내부에서 수행되는 네거티브 피드백 제어, 예컨대, 비례 적분 미분(PID) 제어기를 통해, n-주파수 RF 발생기(508) 내부에서 시드 RF 전압(도 7 참조)의 진폭(A'_i) 및 위상(

)이 생성된다. 달리 말하면, PID 및 MCU는, 측정된 값들(V_ime 및

)에 대한 응답으로, n-주파수 RF 발생기(508)의 조정을 용이하게 하여, RF 매치(502) 하류에 원하는 전압 및 위상이 달성된다. 피드백 제어는, 각각의 주파수 f_i에 대해 수행되며, 여기서, i = 2, 3, ... n인 한편 A'₁ 및

은 일정하다.Measured parameters (V _ime and

) satisfies equations (8) and (9) within a user-defined tolerance, no adjustments are performed on the n-frequency RF generator 508 . User-defined tolerances are typically heuristic. A user-defined tolerance of the amplitude ratio (Equation (8)) is about 5 percent, such as about 3 percent to about 7 percent, such as about 4 percent to about 6 percent. The user-defined tolerance for the relative angle (Equation (9)) is from about 3 degrees to about 8 degrees, such as from about 4 degrees to about 6 degrees. However, if the algorithm of operation 621 is V _ime and

If not satisfied by the measured values of n-frequency, via a negative feedback control, eg, a proportional integral derivative (PID) controller, performed inside a micro control unit (MCU), as illustrated in operation 622 , the n-frequency Amplitude (A′ _i ) and phase (A′ i ) of the seed RF voltage (see FIG. 7 ) inside RF generator 508 (

) is created. In other words, the PID and MCU are measured values (V _ime and

), facilitating adjustment of the n-frequency RF generator 508 to achieve the desired voltage and phase downstream of the RF match 502 . Feedback control is performed for each frequency f _i , where i = 2, 3, ... n while A' ₁ and

is constant

In one example, operation 620 is followed by operation 621 . If operation 621 is satisfied, processing of the substrate proceeds without adjustment for voltage and phase. If operation 621 is not satisfied, operation 622 is performed, and operations 620-622 are repeated until operation 621 is satisfied.

에 의해 복소 값 임피던스 Z_ime(도 7에 도시됨)가 결정되며, 여기서, Y_ime는 주파수 f_i에서의 어드미턴스이고, 이는, n-주파수 RF 매치(502) 내부의 RF 매칭 조건으로부터 도출되고, 수학식 (10)에서 V_ime를 계산하는 데 사용될 수 있다:In some examples, the n-frequency RF voltage monitor 509 may not be accurate enough at frequencies above 40 MHz, because both the RF voltage and current downstream of the RF match 502 are relatively high, This is because the phase angle between the two is close to 90 degrees. At a phase angle of about 90 degrees, a small difference, such as 1 degree, can result in a large difference in power and lead to erroneous readings of RF voltage and/or current. In such cases,

The complex-valued impedance _{Z ime} (shown in FIG. 7 ) is determined _by It can be used to calculate V _ime in Equation (10):

(10)

(10)

Here, P _ime is the power delivered to a process chamber, such as the process chamber 501 shown in FIG. 5 , at a frequency f _i . The measure of Z _ime is calibrated by a vector network analyzer (not shown) disposed in the RF match 502 . Therefore, Equation (10) is very accurate.

)을 측정하는 데 사용되고, 이는, 위상각들의 절대 값을 측정할 때 계통적 오차들을 포함한다는 것이 유의된다. 그러나, 계통적 오차는 수학식 (9)에서의 감산에 의해 소거된다. 부가적으로, 도출된 값들의 계통적 오차는 시간 평균 변수들을 사용함으로써 감소되며, 따라서, 도출된 결과들의 정확성이 개선된다. 결과적으로, 수학식 (9)에서의 오차의 영향이 완화될 수 있다.The n-frequency RF voltage monitor 509 measures the phase angles (

), which includes systematic errors when measuring the absolute value of phase angles. However, the systematic error is canceled by subtraction in Equation (9). Additionally, the systematic error of the derived values is reduced by using time-averaged variables, thus improving the accuracy of the derived results. As a result, the influence of the error in Equation (9) can be mitigated.

FIG. 7 is a block diagram of the n-frequency RF generator 508 illustrated in FIG. 5 . An n-frequency RF generator 508 includes a phase locked loop (PLL) circuit 720 , a frequency divider 722 , an MCU 724 , a user interface 726 , and one or more generators 728a-728c (three are shown). ), and one or more power amplifiers 711 (three are shown), each coupled to a respective generator 728a-728c. The PLL circuit 720 receives a signal from a crystal oscillator or external clock generator 710 and generates a clock signal of CLK = N·f _n , where N is an arbitrary integer, eg, 2 ² - 2 ⁶ . . The CLK signal is transmitted to a frequency divider 722 to produce a set of CLK signals CLK i, i = 1, ... n, each configured to produce an amplitude and a phase at a frequency of f _i . is transmitted to the respective generators 728a-728c.

를 측정하는 n-주파수 RF 전압 모니터(이를테면, n-주파수 RF 전압 모니터(509))에 송신된다. 수학식 (10)에 도시된 바와 같이, V_ime는 n-주파수 RF 매치(502)에서의 전압의 측정치로 대체될 수 있다. V_ime 및

의 값들은 MCU(724)에 제공되며, 이는, 측정된 값들(V_ime,

) 및 사용자 인터페이스(726)에서 사용자에 의해 입력된 목표 값들(V_im,

)로부터 도 6에 도시된 바와 같은 PID 제어기를 통해 시드 RF 전압에 대한 진폭(A'_i) 및 위상(

)을 계산한다. 진폭(A'_i) 및 위상(

)은, V_ime 및

의 측정된 값들에 대한 조정을 표현한다. 일단 V_ime 및

의 측정된 값들이 V_im 및

의 목표 값들과 각각 매칭하면, 도 1 및 도 5에 예시된 전극(105)에 RF 신호가 인가된다.The CLK signal is also expressed as V _ime at f _i and

is transmitted to an n-frequency RF voltage monitor (eg, n-frequency RF voltage monitor 509 ) that measures As shown in equation (10), V _ime can be replaced with a measure of the voltage at the n-frequency RF match 502 . V _ime and

The values of are provided to the MCU 724, which is the measured values V _ime ,

) and target values (V _im , entered by the user in the user interface 726 )

) from the amplitude (A′ i ) and phase (A′ _i ) and phase (

) is calculated. Amplitude (A' _i ) and Phase (

), V _ime and

Expresses the adjustment to the measured values of . Once _Vime and

The measured values of V _im and

If each matches the target values of , the RF signal is applied to the electrode 105 illustrated in FIGS. 1 and 5 .

및

의 정보를 사용하여, CLKi = N·f_i에서의 동위상 및 직교 위상(IQ; In-and-Quadrature phase) 변조 동작은

(p = 0, 1, ... N-1)의 디지털 시드 신호를 합성하며, 결국, 디지털-아날로그 변환기(DAC)(830)에서 디지털 시드 신호가

의 아날로그 시드로 변환된다. 도 7에 도시된 바와 같이, RF 발생기로부터의 신호(

)는, 전력 증폭기(711)에 의해

로 증폭된다.

의 증폭된 신호는 n-주파수 RF 매치(502)에 송신되며, 이는, 증폭된 신호를 RF 매치의 출력에서

로 변환한다.8 shows a block diagram of an amplitude and phase generator 728a in accordance with an embodiment of the present disclosure that may be combined with one or more embodiments described above. It will be appreciated that generators 728b and 728c are similarly configured. received from the MCU 724 shown in FIG.

and

Using the information in CLKi ₌ N·fi , the in-and-quadrature phase (IQ) modulation operation is

(p = 0, 1, ... N-1) synthesizes the digital seed signal, and eventually the digital seed signal in the digital-to-analog converter (DAC) 830 is

is converted to the analog seed of As shown in Figure 7, the signal from the RF generator (

) by the power amplifier 711

is amplified by

The amplified signal of is sent to an n-frequency RF match 502, which converts the amplified signal to the output of the RF match.

convert to

의 형태로 n-세트의 RF 전압들을 측정하며, 여기서, V'_ime 및 V_ime가 환산 계수(scale factor)에 의해 관련된다. 주파수 분할기(722)는, n-세트의 CLK i(i = 1, ... n)를 생성하여 f_i의 주파수에서 개개의 IQ 검출기들(936a-936c)(3개가 도시됨)을 동작시킨다. IQ 검출기들(936a-936c)은, 입력 RF 전압(

)으로부터 V_ime 및

를 도출한다.9 is a diagram of an n-frequency RF voltage monitor 509 receiving a fundamental clock signal of CLK = N·f _n from an n-frequency RF generator 508 . An analog voltage detector 902 , such as a capacitive voltage divider, at a frequency of f _i (i = 1, ... n)

Measure an n-set of RF voltages in the form of , where V' _ime and V _ime are related by a scale factor. Frequency divider 722 generates n-sets of CLK i (i = 1, ... n) to operate individual IQ detectors 936a - 936c (three shown) at the frequency of f _i . . IQ detectors 936a-936c are connected to the input RF voltage (

) from _Vime and

to derive

의 아날로그 입력을

의 디지털 값으로 변환한다. 디지털 값은, ROM(1039)으로부터의

및

와 곱해진다. 변환된 신호는 저역 통과 필터들(LPF)(1040)에 송신된다. 저역 통과 필터들은,

및

의 출력을 생성한다. 저역 통과 필터들의 출력은 디지털 신호 프로세서(DSP)(1041)에 송신된다. DSP(1041)는 좌표 회전 디지털 컴퓨터(CORDIC; coordinate rotation digital computer)를 포함할 수 있다. V_ime 및

를 도출하기 위해 CORDIC 알고리즘 및 다른 디지털 신호 처리가 활용된다.10 illustrates a block diagram of an IQ detector 936 at a frequency of f _i (i = 1, ... n). Analog-to-digital converter (ADC) 1038 , from analog voltage detector 902

analog input of

converted to a digital value of The digital value is from ROM 1039

and

is multiplied with The transformed signal is sent to low pass filters (LPF) 1040 . Low-pass filters are

and

produces the output of The output of the low pass filters is sent to a digital signal processor (DSP) 1041 . The DSP 1041 may include a coordinate rotation digital computer (CORDIC). V _ime and

CORDIC algorithms and other digital signal processing are utilized to derive

11 illustrates a method 1100 of controlling ion bombardment in a process chamber, according to an embodiment of the present disclosure, which may be combined with one or more embodiments described above. During operation 1110 , a first RF signal having a first frequency, a first amplitude, and a first phase is transmitted from the RF generator to an electrode embedded in a substrate support within the process chamber.

During operation 1120 , a second RF signal having a second frequency, a second amplitude, and a second phase is transmitted from the RF generator to the electrode. In one embodiment that may be combined with one or more embodiments described above, the second RF signal has a harmonic frequency of the frequency of the first RF signal. During operation 1130 , a second RF signal is adjusted relative to the first RF signal in response to measurements of a first amplitude, a first phase, a second amplitude, and a second phase. In one embodiment that may be combined with one or more embodiments described above, the amplitude and phase for the seed RF voltage as discussed above is determined based on measurements of the first RF signal and the second RF signal. The amplitude and phase of the seed RF voltage may be used to tune the second RF signal. At operation 1140 , as a result of the RF modulation, ion bombardment to the substrate increases and particle generation on a showerhead disposed within the chamber decreases.

이 거의 최소가 되는 위상들(

, i = 2, ... n)을 식별함으로써 샤워헤드로부터 생성되는 입자들을 감소시킨다.

(i = 2, ... n)에서,

가 거의 최대가 되는 것이 또한 식별되며, 그에 따라, 기판 상의 증착 또는 식각이 최대화되면서 동시에 샤워헤드로부터의 입자 생성이 감소된다.

은 식각 또는 증착 동안의 기판에 대한 이온화된 입자 충돌에 대응하고,

은 샤워헤드에 대한 이온화된 입자 충돌에 대응한다. 따라서, 기판 지지부 상의 전압이 최대화되고 샤워헤드 상의 전압이 최소화되는 위상들을 식별함으로써, 샤워헤드에서의 이온화된 입자 충돌이 최소화(샤워헤드로부터의 입자 박피가 감소)되는 한편, 기판에서의 또는 그에 인접한 증착 및/또는 식각이 증가 및/또는 최대화된다.Utilization of method 1100 for plasma treatment, as indicated above, includes:

These near-minimum phases (

, i = 2, ... n) to reduce the particles generated from the showerhead.

At (i = 2, ... n),

It is also identified that n is near a maximum, thereby maximizing deposition or etching on the substrate while simultaneously reducing particle generation from the showerhead.

counteracts ionized particle bombardment to the substrate during etching or deposition,

corresponds to ionized particle impact on the showerhead. Thus, by identifying phases in which the voltage on the substrate support is maximized and the voltage on the showerhead is minimized, ionized particle bombardment in the showerhead is minimized (reduced particle exfoliation from the showerhead), while at or near the substrate. Deposition and/or etching is increased and/or maximized.

While the foregoing is directed to embodiments of the present disclosure, other and additional embodiments of the disclosure may be devised without departing from the basic scope of the disclosure, which is scoped by the following claims. is determined by

Claims (20)

A system for processing a substrate comprising:
a process chamber defining a process volume therein;
a substrate support disposed within the process volume;
a showerhead disposed in the process volume opposite the substrate support;
an electrode disposed in the process volume;
an RF generator coupled to the electrode by an RF match, wherein the RF generator and the RF match include a first RF signal having a first frequency, a first amplitude, and a first phase, and a second frequency, a second amplitude, and a second frequency. configured to supply a second RF signal having two phases to the electrode;
a voltage monitor configured to detect a voltage applied to the electrode;
a first connection coupled to the RF generator and the voltage monitor and coupled between the RF generator and the voltage monitor, the RF generator configured to receive a first signal from the voltage monitor via the first connection;
a second connection coupled to the RF generator and the RF match and coupled between the RF generator and the RF match, the RF generator configured to receive a second signal from the RF match via the second connection; and
coupled to the RF generator, and adjusting the second RF signal relative to the first RF signal in response to measurements of the first amplitude, the first phase, the second amplitude, and the second phase to heat the substrate. A system for processing a substrate, comprising: a controller configured to generate ions for etching. According to claim 1,
and a time averaged self-biased DC voltage generated on a surface of a substrate disposed on the substrate support. According to claim 1,
wherein the first frequency and the second frequency are harmonics. 4. The method of claim 3,
wherein the first frequency and the second frequency are adjacent harmonic frequencies. According to claim 1,
wherein the RF generator supplies more than two RF signals to the electrode. 6. The method of claim 5,
wherein the more than two RF signals include harmonic frequencies. According to claim 1,
and particle generation on the showerhead is minimized as a result of the adjustment to the second RF signal. According to claim 1,
wherein the number of ions to etch is maximized adjacent a substrate disposed on the substrate support. According to claim 1,
wherein the electrode is embedded in the substrate support, and wherein a surface area of the substrate support is less than a surface area of the showerhead. An apparatus for processing a substrate, comprising:
a substrate support having a surface area and disposed within a process volume of a process chamber;
a showerhead having a surface area and disposed opposite the substrate support in the process volume of the process chamber, wherein a surface area of the showerhead is greater than a surface area of the substrate support and faces a surface area of the substrate support;
an electrode disposed in the process volume;
an RF generator coupled to the electrode by an RF match, wherein the RF generator and the RF match include a first RF signal having a first frequency, a first amplitude, and a first phase, and a second frequency, a second amplitude, and a second frequency. configured to supply a second RF signal having two phases to the electrode;
a second connection coupled to the RF generator and the RF match and coupled between the RF generator and the RF match, the RF generator configured to receive a second signal from the RF match via the second connection; and
coupled to the RF generator, modulates the second RF signal relative to the first RF signal in response to measurements of the first amplitude, the first phase, the second amplitude, and the second phase to remove ions and a controller configured to generate, wherein the number of ions is maximized adjacent the substrate support and minimized adjacent the showerhead. 11. The method of claim 10,
wherein the first frequency and the second frequency are harmonics. 12. The method of claim 11,
and the RF generator supplies more than two RF signals to the electrode. 12. The method of claim 11,
wherein particle generation on the showerhead is minimized as a result of the adjustment to the second RF signal. 12. The method of claim 11,
and a time averaged self-biased DC voltage generated on a surface of a substrate disposed on the substrate support. 11. The method of claim 10,
and the electrode is embedded in the substrate support. 11. The method of claim 10,
a voltage monitor coupled to the RF match and downstream of the RF match;
a first connection coupled to the RF generator and the voltage monitor and coupled between the RF generator and the voltage monitor, the RF generator configured to receive a first signal from the voltage monitor via the first connection, wherein the voltage the monitor is configured to detect a voltage applied to the electrode;
An apparatus for processing a substrate, further comprising: An apparatus for processing a substrate, comprising:
a substrate support having a surface area and disposed within a process volume of a process chamber;
a showerhead having a surface area and disposed opposite the substrate support within the process volume of the process chamber;
an electrode disposed within the process volume;
an RF generator coupled to the electrode by an RF match, wherein the RF generator and the RF match include a first RF signal having a first frequency, a first amplitude, and a first phase, and a second frequency, a second amplitude, and a second frequency. configured to supply a second RF signal having two phases to the electrode, wherein the RF generator supplies three or more RF signals comprising harmonic frequencies to the electrode;
a voltage monitor configured to detect a voltage applied to the electrode;
a first connection coupled to the RF generator and the voltage monitor and coupled between the RF generator and the voltage monitor, the RF generator configured to receive a first signal from the voltage monitor via the first connection; and
coupled to the RF generator, modulates the second RF signal relative to the first RF signal in response to measurements of the first amplitude, the first phase, the second amplitude, and the second phase to remove ions and a controller configured to generate, wherein the number of ions is maximized adjacent a surface area of the substrate support and minimized adjacent a surface area of the showerhead. 18. The method of claim 17,
wherein the first frequency and the second frequency are harmonics. 18. The method of claim 17,
a second connection coupled to the RF generator and the RF match and coupled between the RF generator and the RF match, wherein the RF generator is configured to receive a second signal from the RF match via the second connection.
An apparatus for processing a substrate, further comprising: 18. The method of claim 17,
and the electrode is embedded in the substrate support, and a surface area of the showerhead is greater than a surface area of the substrate support and faces a surface area of the substrate support.

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