Enhanced atomic layer etching process with optimized airflow control for semiconductor manufacturing

Abstract

The invention discloses an enhanced atomic layer etching process with optimized gas flow control for semiconductor manufacturing to improve gas flow control. According to the process, a method for keeping the constant inert gas flow in the surface modification and sputtering steps is introduced, the gas exchange time is remarkably shortened, and the cycle efficiency is improved. Through the preset fixed set values of the MFCs and the valve, the operation is simplified, and the stable and consistent product quality is ensured.

Description

Cross-references to related applications

[0001] This invention claims priority to U.S. Patent Application No. 18 / 791,471, filed August 1, 2024. Technical Field

[0002] This invention relates to the field of semiconductor manufacturing, and more specifically, to atomic layer etching (ALE) equipment and processes for manufacturing semiconductor devices, particularly to the control of gas flow rate in the ALE process to improve efficiency, accuracy and throughput in semiconductor etching. Background Technology

[0003] Reactive ion etching (RIE) is a key technology in semiconductor manufacturing. In RIE, various substances, including neutral particles, free radicals, and ions, collectively influence the etching process. A crucial characteristic of RIE is the synergistic effect between ion flux and neutral particle flux, which significantly enhances the etching rate. This synergistic effect was first described by Coburn and Winters in their 1979 article, "Ion-and-electron-assisted gas-surface chemistry—an important effect in plasma etching," published in the *J. Appl. Phys.*, Vol. 50, pp. 3189-3196. They reported that the etching rate of silicon increased when using argon ion beams, XeF2 neutral beams, and a combination of both. Furthermore, Gottscho et al. proposed a model in "Microscopic uniformity in plasma etching" (J. Vac. Sci. Technol. B10, pp. 2133-2147, 1992) to quantify the effect of this synergistic effect on the etching rate (ER):

[0004] Where υ represents the volume (cm³) removed from the saturated surface by a unit bombardment energy. 3 / eV), E i For ion energy (eV), J i The ion flux reaching the surface (cm) 2 / s), v n Volume removed (cm³) for each neutral particle in the reaction 3 ), J n Let s be the flux of neutral particles reaching the surface, and s be the adhesion probability of neutral particles on the bare surface.

[0005] To achieve efficient RIE, the coexistence of ion flux and neutral particle flux is necessary to leverage the synergistic effect discovered by Coburn and Winters. However, achieving a balance between these two factors in modern etching equipment has become increasingly complex, especially as etching dimensions tend towards nanoscale high aspect ratio (HAR) structures. Achieving uniform etching on 300mm wafers and ensuring consistent repeatability in mass production also presents additional challenges.

[0006] Over the past few decades, etching equipment has undergone numerous improvements to enhance etching uniformity. For example, plasma sources have evolved from single-coil structures (see U.S. Patent No. 4,948,458, Ogle) to multi-coil structures (see U.S. Patent No. 6,164,241, Chen et al.). Plasma sources can employ inductively coupled plasma (ICP) or transformer-coupled plasma (TCP) structures. Furthermore, gas injection techniques have been improved, employing multiple injection ports to ensure plasma uniformity within the vacuum chamber, as described in U.S. Patent Nos. 8,231,799 (Bera et al.) and 10,825,659 (Treadwell). Further improvements include optimization of the electrostatic chuck (ESC) to provide multiple independently temperature-controlled zones (see U.S. Patent Nos. 9,713,200, Pease; and 10,056,225, Gaff et al.).

[0007] A radio frequency (RF) power generator coupled to the ESC provides an additional bias voltage to the ions in addition to the plasma sheath. This coupling is typically achieved via a DC blocking capacitor to prevent electrons from flowing to ground, thereby helping to establish a stable plasma sheath (see U.S. Patent No. 5,302,240, Hori et al.). Furthermore, to improve ion energy and angular momentum distribution, various pulsed schemes of the RF power generator are implemented to maximize the synergistic effect between ions and neutral particles, as described in U.S. Patent Nos. 8,264,154 (Banner et al.) and 10,121,639 (Kanarik). Wang et al., in “Experimental demonstration of multifrequency impedance matching for tailored voltage waveform plasmas” (J.Vac.Sci.Technol.A37,021303, pp. 1-11, 2019), also proposed a controllable waveform RF power generator for precise control of ion energy.

[0008] Furthermore, to improve performance, gas can be supplied via a cyclic pulse method, as described in U.S. Patent No. 10,121,639 (Kanarik). This method divides the RIE process into multiple steps, each optimized using a different process gas.

[0009] Despite these improvements, achieving high consistency in critical dimensions (CD), loading effects, and profiles on 300mm wafers remains a significant challenge and often requires substantial costs.

[0010] To overcome the limitations of RIE, ALE technology was developed. ALE equipment evolved from RIE equipment, but it has lower requirements for achieving uniformity on 300mm wafers. However, due to the characteristics of its process steps, ALE has its own unique requirements.

[0011] Karanik et al. introduced ALE technology in "Overview of atomic layer etching in the semiconductor industry" (J.Vac.Sci.Technol.A33, pp. 020802 1-14, 2015), and Lill further explored this technology in her book "Atomic Layer Processing: Semiconductor Dry Etching Technology" (Wiley-VCH GmbH, 2021). Anisotropic ALE enables the removal of material layers with atomic precision and is an etching technique utilizing sequential self-limiting reactions. The basic ALE process consists of two steps: a surface modification step and a sputtering step for removing the modified layer. The surface modification step is used to form a thin reactive layer of defined thickness, which is easier to remove than the unmodified material. Subsequently, the reactive layer is removed by the sputtering step, while retaining the underlying substrate, thus resetting the surface for the next cycle. The amount of material removed is quantified over multiple cycles, which can be achieved by thermal energy obtained from heating the wafer or by kinetic energy provided by ions from an inert gas. The isotropic process uses thermal energy to remove the modified layer, and the relevant technology is described in U.S. Patent No. 10,208,383 (George et al.); while when high-energy ions are used, the removal process is carried out by sputtering.

[0012] The anisotropic ALE process, which this invention focuses on, has been used to etch a variety of materials, demonstrating its broad applicability, for example:

[0013] Si and Ge: as described in U.S. Patent No. 10,727,073 (Tan et al.);

[0014] SiO2: as described in U.S. Patent No. 9,620,382 (Oehrlein et al.);

[0015] C: As described in U.S. Patent Publications No. 2017 / 0316935 and No. 2022 / 0216050 (Tan et al.);

[0016] Tungsten (W): as described in U.S. Patent Publication No. 2020 / 0286743 (Lai et al.) and No. 10,096,487 (Yang et al.);

[0017] Cobalt (Co): as described in U.S. Patent No. 10,096,487 (Yang et al.);

[0018] Ruthenium (Ru): as described in U.S. Patent Publication No. 2022 / 0199422 (Yang et al.);

[0019] Other refractory metals and materials with high surface bonding energy, such as those described in U.S. Patent No. 11,450,513 (Yang et al.);

[0020] Copper (Cu): As described in WIPO International Publication No. 2022 / 046429 (Yang et al.);

[0021] GaN and other III-V group materials: as described in U.S. Patent No. 10,056,264 (Yang et al.);

[0022] MRAM: as described in U.S. Patent No. 10,749,103 (Tan et al.);

[0023] EUV graphical representation: as described in U.S. Patent No. 9,922,839 (Wise et al.);

[0024] Surface smoothing of various materials: as described in U.S. Patent No. 10,304,659 (Karanik et al.).

[0025] Furthermore, deposition steps are often introduced during ALE, either between ALE steps or as independent steps, to improve performance, particularly in controlling the contours of the structure to be etched. For example, selective deposition on carbon-containing materials can improve ALE performance (see U.S. Patent Publication No. 2017 / 0316935, Tan et al.). As another example, in the method disclosed in U.S. Patent No. 9,805,941 (Karanik et al.), atomic layer deposition (ALD) is performed alternately with ALE in the same plasma chamber to prevent performance degradation during etching, improve selectivity, and coat sensitive layers in the wafer.

[0026] The different chemical reactions, particle morphologies, and plasma energy compositions involved in surface modification and sputtering steps facilitate more precise control of the flux of ions, electrons, and neutral particles, thereby expanding the process window. This step separation mechanism contributes to the realization of self-limiting reactions, which is crucial for maintaining an ideal etching process, namely ensuring uniformity, smoothness, and selectivity. Karanik et al., in "Predicting synergyin atomiclayer etching" (J.Vac.Sci.Technol.A35, pp. 05C302 1-7, 2017), defined the ALE synergy factor as follows:

[0027] Here, EPC (Etch Per Cycle) represents the total thickness of material removed in one cycle (usually the average of multiple cycles); the values ​​of "α" and "β" are the (non-ideal) contributions from the surface modification step and the sputtering step, respectively. Ideally, these two steps would not etch independently, but when combined, the synergy factor would approach 100%. However, in reality, due to the presence of ions in the plasma, which generate neutral particles to modify the surface, the RIE effect in the surface modification step is unavoidable; similarly, physical sputtering of the underlying unmodified layer in the sputtering step is also unavoidable.

[0028] In the surface modification step of ALE (Alternating Electrode Process), it is desirable to avoid ion bombardment by the plasma. However, the unintended introduction of RIE (Residual Injection Effusion) in this step presents a challenge. Since ion bombardment of the substrate surface is difficult to completely avoid, conventional ALE struggles to maintain ideal etching characteristics. Traditional ALE methods are ineffective at eliminating these RIEs, resulting in suboptimal etching performance, especially as device structures become increasingly complex and their dimensions shrink. RIEs in the ALE process cause non-uniform layer removal and undesirable etching profiles, which is particularly severe in advanced device manufacturing; even small deviations can significantly impact device performance and yield.

[0029] To address this problem, U.S. Patent No. 9,362,131 (Agarwal et al.) proposed a solution: using an electron beam source, in the passivation step (i.e., the surface modification step), a remote plasma source is used to supply passivating material to the main chamber, and the ion energy is controlled below the etching threshold; while in the etching step, the material flow from the remote plasma source is stopped and the ion energy is increased above the etching threshold. This solution requires the introduction of an additional remote source, increasing system complexity and cost.

[0030] In addition to enhancing the ALE synergistic effect, it is also necessary to increase the ALE rate. For example, US Patent No. 10,763,083 (Yang et al.) uses high-energy ions (greater than 150 eV) to remove the modified layer. Another approach is to provide a bias voltage for the ions in the plasma by applying pulses to an RF power generator (which is coupled to the ESC). WIPO International Publication No. 2023 / 183129 discloses a method to reduce the etching time of the sputtering step to between 10 ms and 600 ms.

[0031] Another approach to improve ALE speed is to relax the self-limiting reaction conditions (see Taiwan Patent No. 1757334, Cottle et al.). Although this speeds up the process, it may sacrifice synergy, thereby reducing ALE performance.

[0032] Standard operation of ALE involves using mass flow controllers (MFCs) to regulate the flow rates of multiple gases. This regulation is typically dynamic and requires continuous adjustments to maintain optimal etching conditions, which increases the complexity of the etching process and potential inconsistencies. Furthermore, transitions between different etching steps (e.g., from surface modification to sputtering) often require complete gas exchange, further extending the overall process cycle time.

[0033] Furthermore, frequent adjustments to gas flow and valve positions during production lead to inefficiencies and unstable process results. These factors limit the yield and scalability of traditional ALE processes, becoming a bottleneck in high-volume semiconductor manufacturing.

[0034] Against this backdrop, ALE processes urgently require innovation to simplify gas management, shorten cycle times, and improve the consistency of etching results. This invention addresses these needs by introducing novel gas flow control and setpoint determination methods, thereby improving the efficiency and reliability of ALE processes in semiconductor manufacturing. Summary of the Invention

[0035] This invention discloses various implementation cases of ALE equipment and processes, and highlights several innovative technologies that significantly improve operating efficiency.

[0036] A typical ALE process uses a first process gas to modify the substrate surface and a second process gas to generate high-energy ions to remove the modified layer. The main innovation of this invention lies in maintaining a stable flow rate of the second process gas throughout the entire ALE process. In some embodiments, this method can maintain a constant flow rate of the second process gas, thus eliminating the need for frequent gas exchanges. This innovation can significantly reduce gas exchange time (a typical bottleneck in conventional ALE systems), thereby shortening the cycle time of the ALE process.

[0037] Furthermore, this invention highlights another key advancement in the development and application of MFCs and valve setpoints. In various embodiments, these setpoints are carefully determined during process development and remain constant throughout production operation. This strategy simplifies operation, ensures consistent performance, and eliminates the need for continuous adjustments during production. This approach not only simplifies operational complexity but also contributes to improved reliability and efficiency of ALE processes.

[0038] In some implementations, the ALE process system further integrates advanced control mechanisms for MFCs and valves. These mechanisms enable precise control of gas flow, which is crucial for maintaining optimal etching conditions. The integration of constant gas flow modes, coupled with fixed setpoints for key components, represents a significant leap forward in ALE process technology.

[0039] In summary, the key innovations detailed in this invention—maintaining a constant flow rate of the second process gas and determining fixed setpoints for the MFC and valves during process development—are crucial for improving the efficiency and consistency of the ALE process. These advancements, evident in various embodiments and applications, mark a significant development in this field and lay the foundation for simpler and more efficient ALE operation. Attached Figure Description

[0040] For greater clarity, the following description will be provided with reference to the accompanying drawings:

[0041] Figure 1A This is a schematic diagram of an exemplary ALE process system in this invention.

[0042] Figure 1B A schematic diagram of a valve with movable parts to adjust the gas flow through the pump.

[0043] Figure 1C This is an exemplary functional diagram of MFC in this invention.

[0044] Figure 2A The waveforms are for the plasma source and bias unit.

[0045] Figure 2B The waveforms of the gases used in the ALE process are shown.

[0046] Figure 3 A flowchart of an exemplary ALE process with a constant second process gas flow rate. Detailed Implementation

[0047] To ensure a full understanding, this section will describe in detail several embodiments of the invention. While some specific details are provided for clarity, modifications and variations thereof are considered appropriate without departing from the scope of the following claims. Conventional methods and components are also referenced herein to highlight the unique features of the invention.

[0048] Figure 1A An ALE process system 100 is schematically illustrated. The system includes a chamber 102. Functions within the chamber are controlled by a controller 140. The chamber 102 is surrounded by a cavity structure 103, forming a vacuum environment suitable for plasma processing. The cavity structure 103 may be made of materials such as aluminum or quartz, wherein the inner surface of the aluminum may be specifically treated to enhance its durability in a plasma environment. For example, the surface may be anodized.

[0049] The plasma source 104 is fixed to the top of the cavity structure 103. Below the plasma source 104 (not shown), there is a window for sealing the cavity 102. This window can be made of materials such as quartz or ceramic, and its inner surface can be coated with a plasma-resistant material, such as yttrium oxide. The plasma source 104 can take various forms, including but not limited to multi-turn coils, and can be cylindrical or conical.

[0050] Plasma source 104 is connected to RF power generator 106. RF power generator 106 can generate single or multi-frequency RF power, with frequency ranges including but not limited to 100kHz, 200kHz, 400kHz, 2MHz, 13.56MHz, 27MHz, 40MHz, and 60MHz. RF power generator 106 is typically connected to a resonator (not shown). The resonator is responsible for matching the output impedance of RF power generator 106 to the RF impedance from chamber 102, taking into account the effects of transmission lines.

[0051] Gas distribution unit 108 is connected to gas distributor 120. Gas source 110 supplies at least a first process gas 112 and a second process gas 114 to gas distributor 120. For silicon ALE processes, the first process gas is typically chlorine, while the second process gas can be argon or helium. An MFC 111 is provided along the flow path of the first process gas 112 to control the gas flow rate. This MFC 111 measures the gas flow rate and regulates the gas flow rate using proportional-integral-derivative (PID) control. A valve 116 is located in the flow path of the first process gas to open or close the flow of the first process gas. In some embodiments, this valve 116 can direct the first process gas to a backup path when not in use. Similarly, for the second process gas 114, a corresponding MFC 113 and valve 118 may optionally be installed in its flow path. Optionally, an additional valve 122 may be provided between the gas distributor 120 and the gas distribution unit 108 to control the gas flow rate entering the chamber 102.

[0052] The gas source 110 may include various gas delivery devices, such as gas boxes. Depending on the specific embodiment, the gas distribution unit 108 may be used as an injector or a spray head. In some embodiments, the injector may be placed in a central position. In other embodiments, multiple injectors may be placed along the sidewalls of the chamber 102. In some configurations, the gas distribution unit 108 is integrated with a window, serving as a spray head while simultaneously sealing the chamber 102. A pressure gauge 124 is used to measure the pressure within the chamber 102. A controller 140 determines the frequency of these pressure measurements and uses the rate of change of pressure within the chamber to determine whether a steady-state pressure condition has been reached.

[0053] Furthermore, chamber 102 includes pump 128 and valve 126. In some embodiments, pump 128 may be a turbomolecular pump (TMP) for extracting unconsumed gases and reaction byproducts from chamber 102 and discharging them to exhaust port 132 via exhaust line 130. The position of the movable part of valve 126, in conjunction with pump 128, is crucial for determining the rate of gas extraction. In one embodiment, the movable part is a movable cover. It should be noted that the movable cover is used herein for illustrative purposes. Valves can take various forms known in the art. For example, valves include, but are not limited to, gate valves, butterfly valves, ball valves, and diaphragm valves. The design of the movable part differs for each type of valve. A drive current can be used to control an actuator to move the movable part; here, the drive current can be a device setpoint.

[0054] like Figure 1B As shown, an exemplary valve 126 includes a valve body 148 with an opening and a movable part 146. The position 150 of the movable part 146 plays a key role in determining the gas flow rate by adjusting the opening size, where this adjustment works in conjunction with the pumping capacity of the pump 128. To adjust the position 150 of the movable part 146, an actuator 142 is provided, controlled by a valve controller 144. The valve controller 144 utilizes valve PID control 145, working in conjunction with the controller 140, to determine the position required to maintain a steady-state chamber pressure based on a setpoint. Typically, valve PID control devices require hundreds of milliseconds to properly position the valve 126, a factor limiting ALE process cycle time, especially during gas exchange. Addressing this bottleneck helps improve process efficiency.

[0055] The controller 140 operates the MFCs, pump 128, and valve 126 to maintain the steady-state chamber pressure as measured by the pressure gauge 124.

[0056] Figure 1C This is a schematic diagram of an exemplary MFC 151. The MFC 151 includes an inlet 152 and an outlet 154 connected via a gas delivery channel 156. A proportional valve (not shown) diverts a portion of the gas into a channel 158. A flow sensor 160 connected to this channel typically employs thermal sensing technology to measure the flow rate based on the temperature difference between two specific points in the flow path. The measured flow rate serves as an indication of the total flow rate in the gas delivery channel 156.

[0057] The MFC also includes a solenoid valve with a spring 162 for positioning a plunger 164. The gas flow through the orifice 163 is determined by the position of the plunger 164. When the plunger blocks the passage within the orifice 163, the gas flow stops. An electromagnetic coil 165 uses the magnetic force generated by the coil current, combined with the spring force of the spring 162, to control the position of the plunger 164.

[0058] Flow sensor 160 transmits its readings to MFC controller 168, which compares these readings to a preset value representing the desired gas flow rate. If a difference exists between the actual and desired flow rates, MFC controller 168 instructs valve actuator 166 to adjust the current in solenoid coil 165, thereby changing the plunger position. This adjustment process continues until the actual flow rate matches the preset value. To expedite this process, MFC controller 168 employs MFC PID control 170. However, this adjustment process can still take hundreds of milliseconds, which is not ideal for ALE processes.

[0059] In some embodiments of the invention, the setpoints for the MFCs and valve 126 are determined during the process formulation development phase. In one embodiment, the setpoints for the MFCs include the drive current of the plunger. The setpoints for the valve may include the drive current of the actuator 142 in valve 126 for moving the movable part 146.

[0060] These settings are stored in a storage medium. MFC settings may be related to the gas type and the specific MFC. Valve settings may also depend on the specific valve being used.

[0061] When this process formulation is used in production, the MFC PID control 170 will be deactivated, significantly reducing the MFC response time. Energizing the solenoid coil 165 quickly and correctly positions the plunger 164. Although some gas is still directed to channel 158 for monitoring by the flow sensor 160, this monitoring is primarily used to confirm whether the actual flow rate matches the expected flow rate, ensuring consistency.

[0062] Similar to the MFC setup, the position 150 of the movable part of valve 126 is also determined during the process formulation development phase. Once the ALE process is started and put into production operation, this valve position will remain unchanged, thereby significantly reducing the time required to establish steady-state chamber pressure when the ALE process formulation is repeatedly used to process multiple substrates.

[0063] Furthermore, chamber 102 includes a chuck 134 for supporting substrate 136. The chuck 134 can be configured in various forms, including but not limited to an electrostatic chuck (ESC) or a vacuum chuck. A biasing unit 138 is connected to the chuck 134 to provide bias for the chuck and the substrate. This biasing helps to enhance ion energy as needed during the process.

[0064] Figure 3 An exemplary ALE process 300 is illustrated. This ALE process 300 begins at step 302, where controller 140 sends a signal to valve controller 144 to move the movable part 146 of valve 126 to its predetermined position 150. The setpoints of actuator 142 have been determined during the process formulation development phase. Valve PID control 145 is deactivated and not used, thereby reducing the settling time for the cover position. Simultaneously, MFC controller 168 receives a signal from controller 140 and applies a preset current to the solenoid coil 165 of the MFCs. These settings, determined during ALE process development, are stored in the storage medium of controller 140, or separately in the valve controller and the MFC controller. The process then proceeds to surface modification step 202, beginning at step 304. Here, a mixture of first and second process gases is delivered from gas distributor 120 to gas distribution unit 108. The mixing ratio of the first and second process gases is determined by the setpoints of MFCs 111 and 113. For example, during silicon etching using ALE, a mixture of chlorine and argon is supplied to gas distribution unit 108 for surface modification. The chlorine to argon ratio ranges from 5:1 to 100:1, preferably exceeding 10:1. In the surface modification step, an appropriate amount of argon helps excite the plasma in chamber 102, as chlorine, being an electronegative gas, would pose a challenge to the excitation process. Therefore, to avoid argon ion bombardment of the substrate surface, the amount of argon is controlled at a low level to maintain the ideal characteristics of the ALE process.

[0065] After the mixed gas is delivered to chamber 102, controller 140 monitors the chamber pressure changes measured by pressure gauge 124 to determine whether a steady state has been reached. Chamber pressure is measured at predetermined intervals, such as every millisecond, every 5 milliseconds, or every 10 milliseconds. Controller 140 calculates the pressure difference between consecutive measurements. If the measured difference is below a set target value, it can be determined that the chamber pressure has reached a steady state.

[0066] Once the steady-state chamber pressure is reached, plasma source 104 receives first RF power from RF power generator 106. In step 306, substrate 136 is exposed to plasma for a predetermined time. Neutral particles (including free radicals) modify the surface of substrate 136, forming a layer with weakened chemical bonds. In the case of silicon etching using ALE, this layer has weakened silicon bond strength due to chlorine adsorption on the surface.

[0067] In step 308, the ALE process transitions from surface modification step 202 to sputtering step 204, as follows: Figure 2A and 2B As shown. Figure 2A The waveforms of plasma source 104 and bias unit 138 are shown, while Figure 2B The process gas exchange process is then demonstrated. During the exchange in step 308, the first process gas 112 is shut off through valve 116, while the second process gas 114 continues to flow uninterruptedly into chamber 102. Notably, the setpoints of MFC 113 and valve 126 remain unchanged during this process, consistent with the present invention. This innovative method minimizes the exchange time with the process gas, thereby significantly shortening the ALE cycle time. Subsequently, in step 308, controller 140 monitors the chamber pressure using pressure gauge 124 until a new steady state dominated by the second process gas 114 is established. Due to the shut-off of the first process gas, the steady-state chamber pressure of the sputtering step is expected to be lower than that of the surface modification step. Lower pressure is beneficial for obtaining higher ion energies and achieving a tighter energy and angular distribution.

[0068] Proceeding to step 310, when a new steady-state chamber pressure is reached, plasma source 104 receives a second RF power. Simultaneously, a bias voltage is applied to chuck 134 to further increase ion energy. In one embodiment, bias unit 138 is an RF power generator capable of producing single or multiple frequencies and connected to chuck 134 via a resonator, as is well known in the art. Alternatively, bias unit 138 may be a custom waveform generator to achieve a tight ion energy distribution. Then, in step 314, substrate 136 is exposed to plasma ions generated by a second process gas for a predetermined duration. This exposure process removes the modified layer formed in the surface modification step.

[0069] like Figure 2AAs shown, a pulsed strategy can be employed to enhance ALE performance. For example, in the surface modification step, the RF power applied to the plasma source 104 can be pulsed to reduce ion bombardment of the substrate surface. In the sputtering step, the plasma source 104 and the bias unit 138 can be synchronously pulse-driven, as is known in the art. The pulsed schemes described above are merely examples. Various different methods exist in the known art for pulsed control of the plasma source and bias. All these variations should be included within the scope of the inventive concept of this invention.

[0070] Finally, in step 314, controller 140 determines whether all ALE cycles have been completed to end ALE process 300.

Claims

1. A process system for performing ALE process, characterized in that, include: The chamber, the internal space of which is maintained in a vacuum environment; A plasma source, connected to an RF power generator, for generating plasma within the chamber; A biasing unit, operatively connected to a chuck; A gas distribution unit, the gas distribution unit being configured to receive a first process gas from a gas source at least through a first MFC, and to receive a second process gas from a gas source through a second MFC; as well as A controller is configured to sequentially operate the surface modification step and the sputtering step of the process system. In the surface modification step, the controller operates the gas distribution unit to receive the first process gas and the second process gas at a predetermined flow rate. In the sputtering step, the controller operates the gas distribution unit to stop receiving the first process gas and maintain a constant flow rate of the second process gas. Certainly.

2. The process system according to claim 1, characterized in that, The valve setting that controls the rate at which gas is drawn from the chamber remains constant throughout the ALE process.

3. The process system according to claim 2, characterized in that, The set value determines the position of the movable part of the valve, wherein the position of the movable part affects the rate at which gas is drawn from the chamber.

4. The process system according to claim 1, characterized in that, Throughout the ALE process, the settings of the first MFC and the second MFC remain unchanged.

5. The process system according to claim 1, characterized in that, The PID control of the first MFC and the second MFC is disabled.

6. The process system according to claim 2, characterized in that, The set value is determined by the controller during the process formulation development stage.

7. The process system according to claim 1, characterized in that, The process system also includes a pressure gauge for measuring the internal pressure of the chamber.

8. The process system according to claim 7, characterized in that, Pressure is measured at predetermined time intervals, and steady-state chamber pressure is reached if the pressure difference between two consecutive measurements is less than a predetermined value.

9. The process system according to claim 8, characterized in that, The controller is also configured to trigger the output of RF power from the RF power generator and / or the bias unit when the steady-state chamber pressure is reached.

10. The process system according to claim 1, characterized in that, The gas distribution unit also includes an injector located at the center of the top of the chamber.

11. The process system according to claim 1, characterized in that, The gas distribution unit also includes a plurality of injectors disposed along the sidewall of the chamber.

12. The process system according to claim 1, characterized in that, The gas distribution unit also includes a spray head.

13. The process system according to claim 1, characterized in that, The bias unit also includes a custom waveform generator.

14. A method for performing an ALE process in a process system, characterized in that, include: a. A movable part of a valve associated with a pump is moved to a position determined according to a preset value by an actuator, wherein, in an ALE process that includes at least a surface modification step and a sputtering step, the position is fixed and the position of the movable part affects the rate at which gas is drawn from the chamber. b. Receive a mixture of the first process gas and the second process gas at a predetermined flow rate through a gas distribution unit, and receive first RF power from an RF power generator through a plasma source; c. Exposing the substrate surface to plasma generated in the chamber for a first predetermined duration, wherein the substrate is placed on a chuck; d. Shut down the first process gas while maintaining the flow rate of the second process gas, wherein the position of the movable part and the set values ​​of the first MFC and the second MFC for the process gas remain unchanged, and the supply of the first process gas is shut off through a valve located between the first MFC and the gas distribution unit; e. Receive second RF power from the RF power generator through the plasma source, and receive bias from the bias unit through the chuck; f. Exposing the substrate surface to a second predetermined duration; and g. Repeat steps a through f until the ALE process is complete.

15. The method according to claim 14, characterized in that, It also includes disabling the PID control of the first MFC and the second MFC.

16. The method according to claim 14, characterized in that, This also includes determining the position of the moving parts of the valve through the controller during the process formulation development stage.

17. The method according to claim 14, characterized in that, It also includes the step of measuring the internal pressure of the chamber, measuring the pressure at predetermined time intervals, and reaching a steady-state chamber pressure if the pressure difference between two consecutive measurements is less than a predetermined value.

18. The method according to claim 17, characterized in that, It also includes outputting RF power from the RF power generator and / or the bias unit when the steady-state chamber pressure is reached.

19. The method according to claim 14, characterized in that, The gas distribution unit also includes an injector placed at the center of the top of the chamber.

20. The method according to claim 14, characterized in that, The gas distribution unit also includes a plurality of injectors disposed along the sidewall of the chamber.

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