Plasma processing device and working method thereof

Abstract

The invention discloses a plasma processing device and a working method thereof, and the plasma processing device comprises a vacuum reaction chamber which is internally provided with a lower electrode assembly; the direct current power supply and the first bias radio frequency power supply are electrically connected with the lower electrode assembly; the controller is used for controlling the direct-current power supply to provide a first pulse voltage for the lower electrode assembly, controlling the first bias radio frequency power supply to provide a first bias radio frequency voltage for the lower electrode assembly, and adjusting the phase difference between the first pulse voltage and the first bias radio frequency voltage to change the voltage of a plasma sheath layer on the surface of the substrate, the frequency of the first pulse voltage is consistent with the frequency of the first bias radio frequency voltage. The device has the advantages that the direct-current power supply, the first bias radio-frequency power supply and the controller are combined, the frequencies of voltages output by the direct-current power supply, the first bias radio-frequency power supply and the controller are controlled to be consistent through the controller, richer bias voltage waveforms are obtained under the condition that clutters are not introduced, and then accurate control over the substrate etching process is achieved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor equipment, and more specifically to a plasma processing device and its operating method. Background Technology

[0002] In semiconductor device manufacturing, extensive micromachining is typically required. Currently, chemical vapor deposition (CVD) and physical vapor deposition (PVD) are commonly used processes for micromachining semiconductor components or substrates, such as in the manufacture of flexible displays, flat panel displays, light-emitting diodes (LEDs), and solar cells. The micromachining process is often accompanied by plasma-assisted processes, which are generally performed within a vacuum reaction chamber. Among these, plasma etching is a key process for shaping the substrate into the designed pattern. The working principle of plasma etching generally involves introducing a reactive gas containing an appropriate etchant or deposition source gas into the vacuum reaction chamber, followed by the input of radio frequency energy to activate the reactive gas, igniting or maintaining the plasma, thereby processing the substrate.

[0003] In plasma etching processes, the reaction environment for substrate treatment is extremely demanding. Factors such as the stability of the vacuum reaction chamber and its internal components, the plasma energy distribution above the substrate, and the stability of the internal process environment are all crucial, directly or indirectly determining the quality of the substrate surface treatment. However, in practical applications, due to various factors (such as equipment response speed, power input, and electrode configuration), the accuracy of controlling the plasma energy and its distribution above the substrate is difficult to guarantee, thus affecting the substrate surface treatment quality. Therefore, improvements to existing equipment are necessary.

[0004] It is understood that the above statements only provide background information related to the present invention and do not necessarily constitute prior art. Summary of the Invention

[0005] Based on the aforementioned technical problems, the purpose of this invention is to provide a plasma processing device and its operating method. This device combines a DC power supply, a first bias radio frequency power supply, and a controller. The controller controls the DC power supply and the first bias radio frequency power supply to make their respective output first pulse voltage and first bias radio frequency voltage have the same frequency, so that the two are superimposed to form a stable bias voltage. Furthermore, the controller adjusts the phase difference between the first pulse voltage and the first bias radio frequency voltage to obtain a rich and controllable bias voltage waveform without introducing clutter, thereby realizing the regulation of the plasma energy state above the substrate and improving the controllability of the substrate etching process.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] A plasma processing apparatus, comprising:

[0008] A vacuum reaction chamber, wherein a lower electrode assembly is provided within the vacuum reaction chamber;

[0009] A DC power supply, which is electrically connected to the lower electrode assembly;

[0010] A first bias radio frequency power supply is electrically connected to the lower electrode assembly;

[0011] A controller is configured to control the DC power supply to provide a first pulse voltage to the lower electrode assembly, and to control the first bias RF power supply to provide a first bias RF voltage to the lower electrode assembly, and to adjust the phase difference between the first pulse voltage and the first bias RF voltage to change the voltage of the plasma sheath layer on the substrate surface, wherein the frequency of the first pulse voltage is the same as the frequency of the first bias RF voltage.

[0012] Optionally, the first bias RF voltage output by the first bias RF power supply is a sinusoidal waveform, and the first pulse voltage output by the DC power supply is a square pulse wave, wherein the first pulse voltage is a negative voltage or zero voltage.

[0013] Optionally, the frequency range of the first pulse voltage is 100kHz-1MHz;

[0014] The frequency range of the first bias RF voltage is 100kHz-1MHz.

[0015] Optionally, the maximum value of the first pulse voltage ranges from -1kV to -50kV.

[0016] Optionally, the peak value of the first bias RF power ranges from 500W to 50kW.

[0017] Optionally, the lower electrode assembly includes an electrostatic chuck, the electrostatic chuck includes a dielectric layer and a metal base located below the dielectric layer, a first electrode is disposed within the dielectric layer, and the DC power supply is connected to the first electrode or the metal base.

[0018] Optionally, the lower electrode assembly includes an electrostatic chuck, the electrostatic chuck includes a dielectric layer and a metal base located below the dielectric layer, a first electrode is disposed in the dielectric layer, and the first bias RF power supply is connected to the first electrode or the metal base.

[0019] Optional, also includes:

[0020] At least one second bias RF power supply is electrically connected to the lower electrode assembly, and the controller controls the second bias RF power supply to provide a second bias RF voltage, the frequency of which is an integer multiple of the frequency of the first bias RF voltage.

[0021] Optional, also includes:

[0022] A source radio frequency power supply is used to provide a source radio frequency voltage to the vacuum reaction chamber to generate plasma.

[0023] Optionally, the maximum value of the source radio frequency power ranges from 100W to 20kW.

[0024] Optionally, a method of operating the aforementioned plasma processing apparatus includes:

[0025] Determine the etching target of the process;

[0026] During the etching process, the controller controls the first bias RF power supply to provide a first bias RF voltage to the downward electrode assembly, and at the same time, the controller controls the DC power supply to provide a first pulse voltage to the downward electrode assembly, wherein the frequency of the first pulse voltage is the same as the frequency of the first bias RF voltage.

[0027] The phase difference between the first bias RF voltage and the first pulse voltage is adjusted according to the etching target.

[0028] Optional, the following steps may also be included:

[0029] Keep the first pulse voltage unchanged;

[0030] The controller adjusts the phase of the first bias RF voltage applied by the first bias RF power supply to adjust the waveform of the first bias RF voltage superimposed on the first pulse voltage.

[0031] Optionally, the first bias RF voltage is a sine wave, and the first pulse voltage is a square wave.

[0032] The controller adjusts the phase of the first bias RF voltage so that the phase difference between the first bias RF voltage and the first pulse voltage is 90 degrees.

[0033] Alternatively, the controller adjusts the phase of the first bias RF voltage so that the phase difference between the first bias RF voltage and the first pulse voltage is 270 degrees.

[0034] Optionally, when the first bias RF voltage is a sine wave, the first pulse voltage is a square wave, and the phase difference between the first bias RF voltage and the first pulse voltage is 90 degrees or 270 degrees, the controller controls the duty cycle of the first stage of the etching cycle to be less than or equal to the duty cycle of the first pulse voltage, and the duty cycle of the first pulse voltage is less than or equal to 50%.

[0035] Optional, the following steps may also be included:

[0036] Keep the first pulse voltage unchanged;

[0037] The controller adjusts the peak value of the first bias RF voltage applied by the first bias RF power supply to adjust the voltage waveform of the plasma sheath layer on the substrate surface.

[0038] Optional, the following steps may also be included:

[0039] Keep the first bias RF voltage unchanged;

[0040] The controller adjusts the maximum voltage value of the first pulse voltage applied by the DC power supply to adjust the maximum voltage value of the plasma sheath layer on the substrate surface.

[0041] Optionally, the plasma processing apparatus further includes at least one second bias radio frequency power supply for providing a second bias radio frequency voltage to the downward electrode assembly, and the operating method further includes the steps of:

[0042] Keep the first bias RF voltage and the first pulse voltage unchanged;

[0043] The controller controls the second bias RF power supply so that the frequency of the second bias RF voltage is an integer multiple of the frequency of the first bias RF voltage.

[0044] Optionally, the plasma processing apparatus further includes a source radio frequency power supply for providing a source radio frequency voltage to the vacuum reaction chamber, and the operating method further includes the steps of:

[0045] Keep the first bias RF voltage and the first pulse voltage unchanged;

[0046] The controller adjusts the source radio frequency voltage applied by the source radio frequency power supply to regulate the plasma concentration in the vacuum reaction chamber.

[0047] Compared with the prior art, the present invention has the following advantages:

[0048] In a plasma processing apparatus and its operating method according to the present invention, the apparatus combines a DC power supply, a first bias radio frequency power supply and a controller. The controller controls the DC power supply and the first bias radio frequency power supply to make the frequencies of their respective output first pulse voltage and first bias radio frequency voltage consistent, so that the two are superimposed to form a stable bias voltage. Then, the controller adjusts the phase difference between the first pulse voltage and the first bias radio frequency voltage to obtain a rich and controllable bias voltage waveform without introducing clutter, thereby realizing the regulation of the plasma energy state above the substrate and improving the controllability of the substrate etching process.

[0049] Furthermore, the device also includes at least one second bias RF power supply, wherein the controller controls the frequency of the second bias RF voltage output by the second bias RF power supply to be an integer multiple of the first bias RF voltage, so that the second bias RF voltage is superimposed with the first bias RF voltage and the first pulse voltage to form a richer and more controllable bias voltage waveform, thereby improving the controllability of the substrate etching process to meet process requirements. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of a plasma processing device according to the present invention;

[0051] Figure 2 for Figure 1 Enlarged schematic diagram of the lower and middle electrode assembly;

[0052] Figure 3 This is a schematic diagram of the control timing of the bias RF voltage when using a single bias RF power supply.

[0053] Figure 4 This is a schematic diagram of the control timing of the DC voltage when using a single DC power supply;

[0054] Figure 5 This is a waveform diagram of a first bias radio frequency voltage and a first pulse voltage according to the present invention;

[0055] Figure 6 This is a schematic diagram of the control timing of the bias voltage in one embodiment of the present invention;

[0056] Figure 7 This is a schematic diagram of the control timing of the bias voltage in another embodiment of the present invention;

[0057] Figure 8 This is a schematic diagram of the control timing of the bias voltage in another embodiment of the present invention;

[0058] Figure 9 This is a schematic diagram of the control timing of the bias voltage in another embodiment of the present invention;

[0059] Figure 10 This is a schematic diagram of the control timing of the bias voltage in another embodiment of the present invention. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0061] It should be noted that, in this document, the terms "comprising," "including," "having," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Unless otherwise specified, an element defined by the phrase "comprising..." or "including..." does not exclude the presence of additional elements in the process, method, article, or terminal device that includes said element.

[0062] It should be noted that the accompanying drawings are all in a very simplified form and use non-precise ratios, and are only used to facilitate and clearly illustrate the purpose of the embodiments of the present invention.

[0063] like Figure 1The diagram shows a schematic of a plasma processing device according to the present invention. The plasma processing device includes: a vacuum reaction chamber 100, which is surrounded by a reaction chamber body and a chamber end cap 101. The reaction chamber body is typically made of a metallic material and includes a side wall 102 and a bottom wall 103. A substrate transfer port (not shown) is provided on the side wall 102 for transferring a substrate W between the inside and outside of the vacuum reaction chamber 100. A vacuum extraction port 104 is provided on the bottom wall 103 to allow a vacuum pump to evacuate the interior of the vacuum reaction chamber 100. The vacuum reaction chamber 100 includes a lower electrode assembly 110 disposed at the bottom. The lower electrode assembly 110 includes an electrostatic chuck 111, the top of which has a bearing surface for supporting the substrate W. The substrate to be processed, transferred into the vacuum reaction chamber 100 through the substrate transfer port, is placed on the top surface of the dielectric layer. Furthermore, the vacuum reaction chamber 100 also includes an upper electrode assembly 120 disposed opposite to the lower electrode assembly 110. The space between the upper electrode assembly 120 and the lower electrode assembly 110 is a processing area for treating the surface of the substrate W. The upper electrode assembly 120 includes a gas spray disk with multiple gas delivery channels. The gas spray disk is connected to a gas supply device, and the process gas from the gas supply device enters the vacuum reaction chamber 100 through the gas delivery channels of the gas spray disk.

[0064] Furthermore, the plasma processing apparatus also includes at least one source radio frequency power supply 130, which is connected to the upper electrode assembly 120 and / or the lower electrode assembly 110. The source radio frequency power supply 130 applies a high-frequency (HF) source radio frequency voltage (frequency range of 100kHz-200MHz) to the upper electrode assembly 120 and / or the lower electrode assembly 110 through a matching network to dissociate the process gas delivered into the cavity by the gas spray disk into plasma, thereby creating a plasma environment between the upper electrode assembly 120 and the lower electrode assembly 110 for etching. This plasma environment contains a large number of active particles such as electrons, ions, excited-state atoms, molecules, and free radicals. These active particles can undergo various physical and / or chemical reactions with the surface of the substrate W to be processed, thereby changing the morphology of the substrate W to be processed and completing the processing of the substrate W. In practical applications, the source radio frequency voltage applied to the cavity by the source radio frequency power supply 130 can be adjusted to regulate the plasma concentration in the vacuum reaction chamber 100.

[0065] To further improve the surface treatment quality of substrate W, the industry typically uses a bias RF power supply to provide a low-frequency (LF) bias RF voltage into the cavity, thereby generating a bias voltage on substrate W. This accelerates the bombardment of substrate W by ions in the plasma, improving the collimation of ion movement during the etching process. With the increasing demand for high aspect ratio etching, in practical applications, the etching stage usually includes multiple etching cycles, comprising a first stage and a second stage. In the first stage, the source RF power supply 130 delivers a high source RF voltage into the cavity to generate plasma, while the bias RF power supply applies a bias RF voltage to the lower electrode assembly 110, accelerating the plasma to obtain high-energy particles that bombard the surface of substrate W to create a recessed structure, i.e., a deep hole. In the second stage, the residual ion compensation stage, the bias RF voltage applied to the lower electrode assembly 110 by the bias RF power supply is reduced or turned off, allowing more electrons to neutralize residual ions at the bottom of the recessed structure of substrate W, facilitating subsequent process advancement.

[0066] During the etching process, as electrons gradually accumulate on the wafer surface, the substrate W is gradually biased to a negative voltage, forming a negative DC bias voltage Vdc on the surface of substrate W. Simultaneously, a plasma sheath forms between the plasma above substrate W and the substrate W. This sheath causes the cations in the plasma to accelerate downwards and bombard the surface of substrate W, thus etching the substrate W. The energy of the cations bombarding the substrate W is determined by the voltage Vsh of the plasma sheath on the surface of substrate W. Let the bias RF voltage output by the bias RF power supply be denoted as V1, and the plasma voltage as Vp. Then, Vsh = Vp - Vdc - V1, where Vdc is proportional to the amplitude of V1.

[0067] like Figure 3The diagram shows the control timing of the bias RF voltage output by a single bias RF power supply and the voltage Vsh of the plasma sheath on the substrate surface, simulated based on this bias RF voltage. In the simulation, the capacitance between the electrode connected to the bias RF power supply and the substrate W is set to the order of nF, and the peak value of the bias RF voltage output by the bias RF power supply is 5kV. Since the bias RF voltage applied by the bias RF power supply typically exhibits a sinusoidal waveform, and after modulation by charged particles in the plasma, the voltage Vsh of the plasma sheath on the substrate surface is approximately a sinusoidal function with the positive value removed and slightly shifted downwards. The broadening of the voltage Vsh of the plasma sheath on the substrate surface is approximately 7kV. This broadening represents the distribution of particles at different voltages starting from 0kV. A 7kV broadening means that particles used for etching are distributed from 0kV to 7kV. This results in ions entering the plasma sheath at different times experiencing different electric fields, thus producing a wide ion energy distribution, which is not conducive to concentrated etching. Etching with lower-energy ions exhibits strong isotropy, while etching with higher-energy ions exhibits strong anisotropy. During etching, especially in high aspect ratio structures, lower-energy ions have a larger divergence angle, easily causing problems such as bowing and tilting. Even with adjustment of the bias RF voltage output from the bias RF power supply, the voltage Vsh of the plasma sheath on the substrate surface remains significantly broadened, making precise adjustment of the voltage Vsh difficult. For example, it is impossible to obtain a narrow distribution of high-energy ion energy distribution functions, especially the single high-energy ion energy distribution function required for high aspect ratio etching. Therefore, plasma processing devices using only a bias RF power supply struggle to achieve the desired control of the etching process to obtain ideal etching morphologies, resulting in significant limitations in their application.

[0068] Based on the above issues, a DC power supply 140 is typically used to directly replace the bias RF power supply to bias the substrate W. For example... Figure 4 The diagram shows the control timing of the DC pulse voltage output by a single DC power supply 140, and the voltage Vsh of the plasma sheath on the substrate surface simulated based on this DC pulse voltage. In the simulation, the capacitance between the electrode connected to the DC power supply 140 and the substrate W is set to the nF level, and the DC pulse voltage output by the DC power supply 140 is either negative or 0, with negative values ​​taking the range of -10kV. Figure 4As shown, because the amplitude of the DC pulse voltage applied to the substrate surface causes ion bombardment of the substrate, resulting in sheath capacitance discharge and a decrease in sheath voltage, Vsh cannot generate a complete square wave. Instead, it experiences a certain absolute decrease within the period. The DC power supply 140 can reduce the broadening of the plasma sheath voltage Vsh on the substrate surface to about 3kV. However, the waveform of the plasma sheath voltage Vsh on the substrate surface is still significantly distorted compared to the waveform of the DC pulse voltage output by the DC power supply 140, and cannot form a complete square wave. This poses a challenge to finely adjusting the plasma sheath voltage Vsh on the substrate surface. In practical applications, the waveform of the DC pulse voltage output by the DC power supply 140 can be changed by connecting an external slope circuit. However, the waveform adjusted by the slope circuit usually contains many other frequencies, making impedance matching difficult. This method introduces more frequencies and more noise, leading to unstable output waveforms and poor controllability, which in turn affects the etching state of the substrate W.

[0069] Based on the above problems, this invention proposes a new solution. Specifically, in this invention, a DC power supply 140 and a first bias RF power supply 150 are combined. A controller 160 controls the DC power supply 140 to provide a first pulse voltage and controls the first bias RF power supply 150 to provide a first bias RF voltage, ensuring that the frequency of the first pulse voltage and the frequency of the first bias RF voltage are consistent so that they are superimposed to form a stable bias voltage. Furthermore, by adjusting the phase difference between the first pulse voltage and the first bias RF voltage, a richer and more controllable bias voltage waveform can be obtained, thereby changing the voltage Vsh distribution of the plasma sheath layer on the substrate surface to obtain the expected ion energy distribution function and improve the control accuracy of etching the substrate W.

[0070] Specifically, such as Figure 1 and Figure 2 As shown, the plasma processing apparatus further includes a DC power supply 140, a first bias radio frequency power supply 150, and a controller 160. The DC power supply 140 is electrically connected to the lower electrode assembly 110; the first bias radio frequency power supply 150 is electrically connected to the lower electrode assembly 110; the controller 160 is used to control the DC power supply 140 to provide a first pulse voltage to the lower electrode assembly 110, and to control the first bias radio frequency power supply 150 to provide a first bias radio frequency voltage to the lower electrode, and to adjust the phase difference between the first pulse voltage and the first bias radio frequency voltage to change the voltage Vsh of the plasma sheath layer on the substrate surface, wherein the frequency of the first pulse voltage is the same as the frequency of the first bias radio frequency voltage.

[0071] In this application, a DC power supply 140 and a first bias RF power supply 150 are combined. A controller 160 controls the DC power supply 140 and the first bias RF power supply 150 so that the first pulse voltage and the first bias RF voltage have essentially the same frequency. This improves their coherence and reduces interference caused by frequency differences, allowing them to superimpose to form a stable bias voltage to bias the substrate W. Simultaneously, the controller 160 adjusts the phase difference between the first pulse voltage and the first bias RF voltage to adjust the range of waveform overlap, thereby adjusting the waveform of the bias voltage formed by their superposition. This allows for the acquisition of a rich and controllable bias voltage waveform without introducing noise, thereby adjusting the voltage Vsh of the plasma sheath layer on the substrate surface, obtaining an ideal ion energy distribution state, and improving the control accuracy of the etching process on the substrate W.

[0072] Furthermore, such as Figure 5 As shown, the first bias RF voltage output by the first bias RF power supply 150 is a sinusoidal waveform, and the first pulse voltage output by the DC power supply 140 is a square pulse wave. The first pulse voltage is either a negative voltage or a zero voltage. The first bias RF voltage and the first pulse voltage have the same frequency so that their overlap range can be adjusted on a half-wave scale, i.e., the phase difference can be adjusted to form a stable and controllable bias voltage. During the etching process, while keeping one voltage constant, adjusting the phase of the other voltage can change the waveform of the bias voltage formed by their superposition, thereby adjusting the voltage Vsh of the plasma sheath layer on the substrate surface to meet different requirements in the etching process. Of course, the waveform forms of the first bias RF voltage and the first pulse voltage are not limited to those described above. In other embodiments, they can also present other forms, which are not limited by this invention.

[0073] Optionally, the frequency range of the first pulse voltage is 100kHz-1MHz; the frequency range of the first bias RF voltage is 100kHz-1MHz. Alternatively, the maximum value of the first pulse voltage ranges from -1kV to -50kV; the peak value of the first bias RF power ranges from 500W to 50kW, typically RF power can be converted into a voltage value based on the chamber impedance; the maximum value of the source RF power ranges from 100W to 20kW. The output power range of the DC power supply 140 is 5kW-200kW, and the output power range of the first bias RF power supply 150 is 500W-50kW. It is understood that in practical applications, the above parameters are not limited to the above numerical ranges; they can be other numerical ranges depending on the actual application requirements and equipment conditions, and this invention does not impose any limitations on this.

[0074] like Figure 1 and Figure 2As shown, the lower electrode assembly 110 includes an electrostatic chuck 111, which comprises a dielectric layer and a metal substrate located below the dielectric layer. The DC power supply 140 and the first bias RF power supply 150 can be fed into the same electrode or different electrodes of the electrostatic chuck 111. This electrode can be the first electrode 112 embedded in the dielectric layer or the metal substrate. That is, the DC power supply 140 can be connected to the first electrode 112 or the metal substrate; the first bias RF power supply 150 can be connected to the first electrode 112 or the metal substrate. In practical applications, the configuration can be adjusted according to actual application requirements and site conditions.

[0075] Furthermore, in this invention, the plasma processing apparatus may further include at least one second bias radio frequency power supply 170. The second bias radio frequency power supply 170 is electrically connected to the lower electrode assembly 110, and the controller 160 controls the second bias radio frequency power supply 170 to provide a second bias radio frequency voltage to the lower electrode assembly 110. That is, the waveform and phase of the second bias radio frequency voltage are modulated by the controller 160. The frequency of the second bias radio frequency voltage is an integer multiple of the frequency of the first bias radio frequency voltage, so that the waveforms of the second bias radio frequency voltage, the first pulse voltage, and the first bias radio frequency voltage are superimposed to form a stable and controllable bias voltage, thereby realizing the adjustment of the voltage Vsh of the plasma sheath layer on the substrate surface.

[0076] Optionally, the second bias RF power supply 170 can be fed into the same electrode or different electrodes as the DC power supply 140 or the first bias RF power supply 150. That is, the second bias RF power supply 170 can be connected to the first electrode 112 in the dielectric layer or to the metal substrate. In practical applications, it can be set according to the actual application requirements and site conditions.

[0077] Based on the same inventive concept, the present invention also provides a method for operating a plasma processing apparatus, the method comprising: determining the etching target of the process; during the etching process, a controller 160 controls a first bias radio frequency power supply 150 to provide a first bias radio frequency voltage to a downward electrode assembly 110, and simultaneously the controller 160 controls a DC power supply 140 to provide a first pulse voltage to the downward electrode assembly 110, wherein the frequency of the first pulse voltage is consistent with the frequency of the first bias radio frequency voltage; and adjusting the phase difference between the first bias radio frequency voltage and the first pulse voltage according to the etching target.

[0078] Based on the above method, the controller 160 controls the first bias RF voltage output by the first bias RF power supply 150 and the first pulse voltage output by the DC power supply 140 to have the same frequency, so that the two can be superimposed to form a stable bias voltage to bias the substrate W without introducing noise of other frequencies. At the same time, the method also adjusts the phase difference between the first bias RF voltage and the first pulse voltage through the controller 160, thereby forming a rich variety of stable and controllable bias voltage waveforms without introducing noise of other frequencies, so as to obtain the ideal voltage Vsh distribution of the plasma sheath layer on the substrate surface and meet the process requirements. This method helps to improve the accuracy of ion movement control during the etching process of the substrate W.

[0079] As described above, in this embodiment, the first bias RF voltage is a sinusoidal waveform, and the first pulse voltage is a square pulse wave. That is, before the controller 160 adjusts the phase difference between the first bias RF voltage and the first pulse voltage, the phase difference between them is 0 degrees. It is understood that the controller 160 can preset and adjust the parameters of the first bias RF power supply 150 and the DC power supply 140 before the etching process begins, so that the expected etching effect can be achieved at the start of the etching process. Of course, real-time adjustment can also be performed during the etching process; that is, the present invention does not limit the timing of the controller 160's control.

[0080] On the other hand, the phase difference between the first bias RF voltage and the first pulse voltage can be achieved by individually adjusting the phase of the first bias RF voltage output by the first bias RF power supply 150, or by individually adjusting the phase of the first pulse voltage output by the DC power supply 140. This invention does not limit the method of adjusting the phase difference. Based on this, the operation method of the plasma processing device further includes the steps of: keeping the first pulse voltage unchanged (waveform, phase, duty cycle, etc. unchanged); and the controller 160 adjusting the phase of the first bias RF voltage applied by the first bias RF power supply 150 to adjust the waveform of the superposition of the first bias RF voltage and the first pulse voltage.

[0081] Because RF power supplies are relatively mature, they offer better control precision and response speed. Furthermore, the RF voltage output by an RF power supply typically consists of a single-frequency voltage, which can be matched with an impedance matching unit to achieve reflection-free output, resulting in a stable waveform free from noise interference. Therefore, the method described above, where the controller 160 adjusts the first bias RF voltage output from the first bias RF power supply 150 to achieve phase difference adjustment, helps to obtain a stable bias voltage, thereby making the etching environment of the substrate W more stable and improving the processing quality of the substrate W.

[0082] In practical applications, such as Figure 5As shown, the controller 160 can adjust the phase of the first bias RF voltage so that the phase difference between the first bias RF voltage and the first pulse voltage is 90 degrees, that is, when the pulse voltage is at its negative maximum value, the first bias RF voltage changes from its positive maximum value to its negative maximum value. The two combined are as follows: Figure 6 The bias voltage waveform is shown. In this embodiment, the controller 160 sets the phase of the first bias RF voltage to 90 degrees in the initial stage, with a peak value of 2kV. Simultaneously, the controller 160 sets the first pulse voltage output by the DC power supply 140 to -10kV with a duty cycle of 50%. The frequencies of both the first bias RF voltage and the first pulse voltage are 400kHz. During simulation calculations, the capacitance between the electrodes connected to the first bias RF voltage and the DC power supply 140 and the substrate W is set to the order of nF. In this embodiment, the maximum energy obtainable by ions, i.e., the maximum voltage Vsh of the plasma sheath on the substrate surface, is 8.5kV, while the ion energy broadening is less than 1kV. By employing the above method, the maximum phase of the sine wave of the first bias RF voltage and the minimum phase of the square wave of the first pulse voltage (because it is a negative voltage) can be synchronized at the beginning of the first stage. This results in the bias voltage formed by the superposition of the first bias RF voltage and the first pulse voltage in the first stage showing a decreasing trend (the absolute value shows an increasing trend), which compensates for the loss of ion current during the etching process. This reduces the broadening of the voltage Vsh of the plasma sheath layer on the substrate surface, making it as constant as possible, thereby obtaining a narrower ion energy distribution and improving the quality of substrate W processing.

[0083] In practical applications, there are also process requirements that necessitate a wider ion energy distribution. For example, in the same etching process, different energies may be used for etching different numbers of material layers. Based on this requirement, the controller 160 can adjust the phase of the first bias RF voltage so that the phase difference between the first bias RF voltage and the first pulse voltage is 270 degrees. For example, such as... Figure 7 As shown, in one embodiment, the controller 160 sets the phase of the first bias RF voltage to 270 degrees in the initial stage, with a peak value of 2kV. Other parameters of this embodiment are the same as those of the controller 160. Figure 6 The parameters are the same in the corresponding embodiments. In this embodiment, the maximum energy that ions can obtain is 10.5kV, while the ion energy broadening is controlled at 7kV. Through the above method, the minimum phase of the sine wave of the first bias RF voltage and the minimum phase of the square wave of the first pulse voltage can be synchronized at the beginning of the first stage. This causes the bias voltage formed by the superposition of the first bias RF voltage and the first pulse voltage in the first stage to show an increasing trend (while the absolute value decreases), thereby increasing the amplitude of the voltage Vsh of the plasma sheath layer on the substrate surface, and thus obtaining a wider ion energy distribution to meet process requirements.

[0084] Based on the above, when the first bias RF voltage is a sine wave, the first pulse voltage is a square wave, and the phase difference between the first bias RF voltage and the first pulse voltage is 90 degrees or 270 degrees, the controller 160 can control the duty cycle of the first stage of the etching cycle to be less than or equal to the duty cycle of the first pulse voltage, and the duty cycle of the first pulse voltage to be less than or equal to 50%, so that the bias voltage in the first stage shows a unidirectional increasing or decreasing trend, so that the voltage Vsh of the plasma sheath layer on the substrate surface in the first stage is continuous, thereby achieving precise control of the ion energy distribution state on the substrate W surface. For example, as... Figure 8 As shown, in one embodiment, the controller 160 controls the duty cycle of the first pulse voltage to be 20%, and the time duty cycle of the first stage is also 20%. The phase of the first bias RF voltage in the initial stage is 135 degrees. Other parameters of this embodiment are the same as those of the first bias RF voltage. Figure 6 The parameters are the same in the corresponding embodiments. In this embodiment, the maximum energy that ions can obtain is 9kV, while the ion energy broadening is controlled to be 0.1kV. In the first stage of this embodiment, the bias voltage shows a unidirectional decreasing trend, and the voltage Vsh of the corresponding plasma sheath layer on the substrate surface is continuously stable. The ion energy bombarding the surface of the substrate W is relatively stable, which helps to obtain the ideal etching morphology of the substrate W.

[0085] On the other hand, as mentioned above, the voltage of the plasma sheath layer on the substrate surface, Vsh, is equal to Vp - Vdc - V1. When V1, i.e., the bias voltage, is positive, Vsh = Vp + |Vdc| - |V1|; when V1 is negative, Vsh = Vp + |Vdc| + |V1|. Therefore, when V1 is negative, the larger its absolute value, the larger the voltage Vsh of the plasma sheath layer on the substrate surface at that stage, thus increasing the energy of ions bombarding the substrate W, which helps to achieve high aspect ratio etching of the substrate W. Therefore, the maximum value of the voltage Vsh of the plasma sheath layer on the substrate surface can be adjusted by regulating the maximum absolute value of the bias voltage, i.e., the maximum absolute value of the superposition of the first bias RF voltage and the first pulse voltage, thereby controlling the energy of ions bombarding the surface of the substrate W.

[0086] Based on the above, the operation method of the plasma processing device further includes the steps of: maintaining the first pulse voltage unchanged; and the controller 160 adjusting the peak value of the first bias radio frequency voltage applied by the first bias radio frequency power supply 150 to adjust the voltage waveform and maximum value of the plasma sheath layer on the substrate W surface. With the phases of the first pulse voltage and the first bias radio frequency voltage unchanged, adjusting the peak value of the first bias radio frequency voltage by the controller 160 can adjust the waveform and maximum value of the bias voltage, thereby changing the distribution and maximum value of the voltage Vsh of the plasma sheath layer on the substrate surface, and achieving control of the plasma state. For example, as... Figure 9 As shown, in one embodiment, the controller 160 controls the peak value of the first bias RF voltage output by the first bias RF power supply 150 to be 4kV. Other parameters in this embodiment are the same as... Figure 6 The parameters are the same in the corresponding embodiment. In this embodiment, the maximum energy obtainable by the ions is 11.5 kV, while the ion energy broadening is controlled to be less than 4 kV. This method increases the maximum value of the plasma sheath voltage Vsh on the substrate surface and the fluctuation range of the ion energy.

[0087] Of course, the bias voltage can be adjusted not only in the manner described above, but also by adjusting the first pulse voltage. Based on this, the operation of the plasma processing device further includes the steps of: maintaining the first bias radio frequency voltage unchanged; and the controller 160 adjusting the maximum voltage value of the first pulse voltage applied by the DC power supply 140 to adjust the maximum voltage value of the plasma sheath layer on the substrate W surface. Adjusting the bias voltage by regulating the first pulse voltage does not change the waveform of the bias voltage, but only changes its maximum value, which helps maintain the waveform of the ion energy distribution at this stage. This method is particularly suitable for high aspect ratio etching processes. In practical applications, different adjustment methods can be adopted according to the specific application requirements.

[0088] On the other hand, the operation method of the plasma processing device further includes the steps of: keeping the first bias radio frequency voltage and the first pulse voltage unchanged; the controller 160 controlling the second bias radio frequency power supply 170 such that the frequency of the second bias radio frequency voltage is an integer multiple of the frequency of the first bias radio frequency voltage. In this method, the frequency of the second bias voltage being an integer multiple of the first bias radio frequency voltage helps to superimpose the waveforms of the two, thereby superimposing them with the first pulse voltage to form a stable bias voltage. The addition of the second bias voltage allows the bias voltage to have a richer and more controllable waveform, thus meeting different process requirements. For example, such as... Figure 10As shown, in one embodiment, the controller 160 controls the second bias RF voltage output by the second bias RF power supply 170 to have a frequency of 800kHz and a peak value of 2kV. Other parameters of this embodiment are the same as those of the second bias RF power supply 170. Figure 6 The parameters are the same in the corresponding embodiments. In this embodiment, the maximum energy obtainable by the ions is 11.5kV, while the ion energy broadening is controlled to 4kV. Through the above method, a richer waveform of the bias voltage and the ion energy distribution can be obtained.

[0089] On the other hand, the operation method of the plasma processing device further includes the steps of: keeping the first bias radio frequency voltage and the first pulse voltage unchanged; and the controller 160 adjusting the source radio frequency voltage applied by the source radio frequency power supply 130 to adjust the plasma concentration in the vacuum reaction chamber 100. In this method, the plasma concentration in the chamber can be adjusted by adjusting the source radio frequency power supply 130.

[0090] In summary, in the plasma processing apparatus and its operating method of the present invention, the apparatus combines a DC power supply 140, a first bias radio frequency power supply 150, and a controller 160. The controller 160 controls the first pulse voltage output by the DC power supply 140 and the first bias radio frequency voltage output by the first bias radio frequency power supply 150, so that the frequency of the first pulse voltage and the frequency of the first bias radio frequency voltage are consistent. Furthermore, the controller 160 adjusts the phase difference between the first pulse voltage and the first bias radio frequency voltage to obtain a rich and controllable bias voltage waveform without introducing clutter, thereby realizing the regulation of the plasma energy state above the substrate W and improving the controllability of the etching process of the substrate W.

[0091] Furthermore, the device also includes at least one second bias RF power supply 170, wherein the controller 160 controls the frequency of the second bias RF voltage output by the second bias RF power supply 170 to be an integer multiple of the first bias RF voltage, so that the second bias RF voltage is superimposed with the first bias RF voltage and the first pulse voltage to form a richer and more controllable bias voltage waveform, thereby improving the controllability of the etching process of the substrate W to meet the process requirements.

[0092] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A plasma processing device, characterized in that, Include: A vacuum reaction chamber, wherein a lower electrode assembly is provided within the vacuum reaction chamber; A DC power supply, which is electrically connected to the lower electrode assembly; A first bias radio frequency power supply is electrically connected to the lower electrode assembly; A controller is configured to control the DC power supply to provide a first pulse voltage to the lower electrode assembly, and to control the first bias RF power supply to provide a first bias RF voltage to the lower electrode assembly, and to adjust the phase difference between the first pulse voltage and the first bias RF voltage to change the voltage of the plasma sheath layer on the substrate surface, wherein the frequency of the first pulse voltage is the same as the frequency of the first bias RF voltage.

2. The plasma processing apparatus as described in claim 1, characterized in that, The first bias RF voltage output by the first bias RF power supply is a sine wave, and the first pulse voltage output by the DC power supply is a square pulse wave. The first pulse voltage is a negative voltage or zero voltage.

3. The plasma processing apparatus as described in claim 1, characterized in that, The frequency range of the first pulse voltage is 100kHz-1MHz; The frequency range of the first bias RF voltage is 100kHz-1MHz.

4. The plasma processing apparatus as described in claim 1, characterized in that, The maximum value of the first pulse voltage ranges from -1kV to -50kV.

5. The plasma processing apparatus as described in claim 1, characterized in that, The peak value of the first bias RF power ranges from 500W to 50kW.

6. The plasma processing apparatus as described in claim 1, characterized in that, The lower electrode assembly includes an electrostatic chuck, which includes a dielectric layer and a metal base located below the dielectric layer. A first electrode is disposed within the dielectric layer, and the DC power supply is connected to the first electrode or the metal base.

7. The plasma processing apparatus as described in claim 1, characterized in that, The lower electrode assembly includes an electrostatic chuck, which includes a dielectric layer and a metal base located below the dielectric layer. A first electrode is disposed within the dielectric layer, and the first bias RF power supply is connected to the first electrode or the metal base.

8. The plasma processing apparatus as described in claim 1, characterized in that, Also includes: At least one second bias RF power supply is electrically connected to the lower electrode assembly, and the controller controls the second bias RF power supply to provide a second bias RF voltage, the frequency of which is an integer multiple of the frequency of the first bias RF voltage.

9. The plasma processing apparatus as claimed in claim 1, characterized in that, Also includes: A source radio frequency power supply is used to provide a source radio frequency voltage to the vacuum reaction chamber to generate plasma.

10. The plasma processing apparatus as described in claim 9, characterized in that, The maximum value of the source radio frequency power ranges from 100W to 20kW.

11. A method of operating the plasma processing apparatus as described in any one of claims 1 to 10, characterized in that, include: Determine the etching target of the process; During the etching process, the controller controls the first bias RF power supply to provide a first bias RF voltage to the downward electrode assembly, and at the same time, the controller controls the DC power supply to provide a first pulse voltage to the downward electrode assembly, wherein the frequency of the first pulse voltage is the same as the frequency of the first bias RF voltage. The phase difference between the first bias RF voltage and the first pulse voltage is adjusted according to the etching target.

12. The method of operating the plasma processing apparatus as described in claim 11, characterized in that, It also includes the following steps: Keep the first pulse voltage unchanged; The controller adjusts the phase of the first bias RF voltage applied by the first bias RF power supply to adjust the waveform of the first bias RF voltage superimposed on the first pulse voltage.

13. The method of operating the plasma processing apparatus as described in claim 12, characterized in that, The first bias RF voltage is a sine wave, the first pulse voltage is a square wave, and the controller adjusts the phase of the first bias RF voltage so that the phase difference between the first bias RF voltage and the first pulse voltage is 90 degrees. Alternatively, the controller adjusts the phase of the first bias RF voltage so that the phase difference between the first bias RF voltage and the first pulse voltage is 270 degrees.

14. The method of operating the plasma processing apparatus as described in claim 11, characterized in that, When the first bias RF voltage is a sine wave, the first pulse voltage is a square wave, and the phase difference between the first bias RF voltage and the first pulse voltage is 90 degrees or 270 degrees, the controller controls the duty cycle of the first stage of the etching cycle to be less than or equal to the duty cycle of the first pulse voltage, and the duty cycle of the first pulse voltage is less than or equal to 50%.

15. The method of operating the plasma processing apparatus as described in claim 11, characterized in that, It also includes the following steps: Keep the first pulse voltage unchanged; The controller adjusts the peak value of the first bias RF voltage applied by the first bias RF power supply to adjust the voltage waveform of the plasma sheath layer on the substrate surface.

16. The method of operating the plasma processing apparatus as described in claim 11, characterized in that, It also includes the following steps: Keep the first bias RF voltage unchanged; The controller adjusts the maximum voltage value of the first pulse voltage applied by the DC power supply to adjust the maximum voltage value of the plasma sheath layer on the substrate surface.

17. The method of operating the plasma processing apparatus as described in claim 11, characterized in that, The plasma processing apparatus further includes at least one second bias radio frequency power supply for providing a second bias radio frequency voltage to the downward electrode assembly, and the operating method further includes the steps of: Keep the first bias RF voltage and the first pulse voltage unchanged; The controller controls the second bias RF power supply so that the frequency of the second bias RF voltage is an integer multiple of the frequency of the first bias RF voltage.

18. The method of operating the plasma processing apparatus as described in claim 11, characterized in that, The plasma processing apparatus further includes a source radio frequency power supply for providing a source radio frequency voltage to the vacuum reaction chamber, and the operating method further includes the steps of: Keep the first bias RF voltage and the first pulse voltage unchanged; The controller adjusts the source radio frequency voltage applied by the source radio frequency power supply to regulate the plasma concentration in the vacuum reaction chamber.

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