Semiconductor process chamber and ignition method

Abstract

This invention relates to a semiconductor process chamber and an ignition method. The semiconductor process chamber includes not only a process cavity for generating plasma, but also a main ignition device, an auxiliary ignition device, and a monitoring device. The auxiliary ignition device in this invention makes plasma ignition within the plasma chamber more stable and reliable, significantly reducing or eliminating semiconductor equipment failure time due to plasma ignition failure. Furthermore, the monitoring device effectively monitors whether plasma ignition is successful, significantly reducing or eliminating the problem of wafers flowing into the next stage of semiconductor manufacturing without plasma processing due to plasma ignition failure, thus preventing wafer scrapping.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology, specifically relating to a semiconductor process chamber and an ignition method. Background Technology

[0002] In the current field of microelectronics manufacturing, plasma technology holds a dominant position. Approximately one-third of the processes in chip manufacturing require plasma technology. Plasma processing occurs within a plasma process chamber, where process gases are dissociated into plasma composed of electrons and ions for substrate surface treatment. However, due to contaminants on the substrate surface, the inherent characteristics of the process gases, or chamber conditioning issues, plasma ignition may fail during the wafer fabrication process within the chamber. Plasma ignition failure not only increases the failure time of semiconductor equipment, but more seriously, it can lead to wafers flowing into the next stage of semiconductor manufacturing without undergoing plasma treatment, directly rendering the wafer unusable. Therefore, there is an urgent need to research processes or technologies to overcome plasma ignition failure. Summary of the Invention

[0003] In order to overcome the problems existing in the prior art, the present invention provides a semiconductor process chamber and ignition method to overcome the existing defects.

[0004] A semiconductor process chamber includes a process cavity for generating plasma. The process cavity includes an upper cover, sidewalls, and a base disposed inside the process cavity for holding a wafer to be processed. An upper electrode is disposed below the upper cover, and a lower electrode is disposed on the base.

[0005] A main ignition device is connected to the upper electrode and / or the lower electrode, an auxiliary ignition device is connected to the upper electrode or the lower electrode, and the monitoring device is also provided on the base;

[0006] The main ignition device is used to provide main ignition energy for generating plasma in the process chamber;

[0007] An auxiliary ignition device is used to provide auxiliary ignition energy for generating plasma in the process chamber;

[0008] The monitoring device is used to detect whether the main ignition device and the auxiliary ignition device have successfully ignited.

[0009] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the upper electrode includes one or a combination of a coil, an electrode plate, a gas distribution plate, and a flow equalization plate.

[0010] In addition to the aspects described above and any possible implementations, a further implementation is provided, wherein the main ignition device includes a first ignition branch and / or a second ignition branch, the first ignition branch including a first radio frequency power supply and a first matching network, wherein the input terminal of the first matching network is connected to the output terminal of the first radio frequency power supply, and the output terminal of the first matching network is connected to the upper electrode; the second ignition branch includes a second radio frequency power supply and a second matching network, wherein the input terminal of the second matching network is connected to the output terminal of the second radio frequency power supply, and the output terminal of the second matching network is connected to the lower electrode.

[0011] In addition to the aspects described above and any possible implementations, a further implementation is provided in which the auxiliary ignition device includes a third radio frequency power supply and a third matching network, wherein the input of the third matching network is connected to the output of the third radio frequency power supply, and the output of the third matching network is connected to the upper electrode or the lower electrode.

[0012] In addition to the aspects and any possible implementations described above, a further implementation is provided in which a groove is provided on the outer side surface of the sidewall, and a plurality of ignition auxiliary electrodes are disposed in the groove; a dielectric cylinder concentric with the sidewall is provided on the inner side surface of the sidewall.

[0013] In addition to the aspects and any possible implementations described above, a further implementation is provided in which an RF access board is disposed between the upper electrode and the upper cover, the RF access board including a base plate disposed concentrically with the cavity and an annular plane erected at the edge of the base plate, the annular plane being opposite to and spaced apart from at least a portion of the ignition auxiliary electrode.

[0014] In addition to the aspects and any possible implementations described above, a further implementation is provided in which a conductor is provided between the radio frequency access board and the auxiliary ignition device, one end of the conductor being connected to the base plate and the other end of the conductor being connected to the output of the third matching network.

[0015] In addition to the aspects described above and any possible implementations, a further implementation is provided in which a dielectric spacer is provided between the upper end face of the dielectric cylinder and the upper electrode.

[0016] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the upper electrode is a gas distribution plate, and the dielectric partition and the gas distribution plate are provided with a plurality of air inlets of the same size and corresponding to each other.

[0017] In addition to the aspects described above and any possible implementation, a further implementation is provided, wherein the monitoring device includes a current sensor, a processing circuit, and a controller connected in sequence; the current sensor is embedded on the lower surface of the edge region of the base for detecting the plasma discharge current and outputting the detected discharge current to the processing circuit; the processing circuit is used to limit, filter, and sample the discharge current before outputting it to the controller; the controller is used to determine whether ignition is successful based on the received current.

[0018] In addition to the aspects described above and any possible implementations, a further implementation is provided in which the current sensor includes a silicon rod covered by a dielectric material, a coil, and a cap post, wherein the coil is wound around the silicon rod, and the cap post seals the dielectric surface of the current sensor in contact with the plasma.

[0019] The present invention also provides an ignition method for a semiconductor process chamber, wherein the method is implemented in the semiconductor process chamber described in the present invention, and includes the following steps:

[0020] (1) Introduce process gas into the chamber;

[0021] (2) Ignition is performed after the air pressure in the chamber stabilizes. If it is the first ignition, the main ignition device is started and the auxiliary ignition device is not required. If it is a repeated ignition, the main ignition device and the auxiliary ignition device are started at the same time.

[0022] (3) Apply the radio frequency energy of the main ignition device or the main and auxiliary ignition devices to the process gas to ionize the process gas into plasma;

[0023] (4) The discharge current of the plasma is monitored using a monitoring device;

[0024] (5) After a certain period of time after ignition, if the monitored current density is greater than or equal to the set threshold, the ignition is successful and the subsequent process begins; if the monitored current density is less than the set threshold, the ignition fails and steps (2)-(5) are repeated.

[0025] In addition to the aspects and any possible implementations described above, a further implementation is provided, which also includes monitoring the number of ignitions, and if ignition fails after the number of ignitions reaches a set upper limit, the process is interrupted and an alarm is triggered.

[0026] Beneficial effects of the present invention

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The semiconductor process chamber of this invention includes not only a process chamber for generating plasma, but also a main ignition device, an auxiliary ignition device, and a monitoring device. The auxiliary ignition device allows additional radio frequency energy to enter the chamber, reducing or even eliminating the impact of contaminants within the chamber on ignition, thereby more efficiently exciting the plasma. This makes plasma ignition within the plasma chamber more stable and reliable, significantly reducing or eliminating semiconductor device failure time due to plasma ignition failure. Furthermore, the monitoring device effectively monitors whether plasma ignition is successful, significantly reducing or eliminating the problem of wafers flowing into the next stage of semiconductor manufacturing without plasma processing due to plasma ignition failure, thus preventing wafer scrap. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a plasma chamber in the prior art;

[0030] Figure 2 This is a schematic diagram of a plasma chamber in the prior art.

[0031] Figure 3 This is a schematic diagram of the structure of the semiconductor process chamber of the present invention;

[0032] Figure 4 This is a second schematic diagram of the structure of the semiconductor process chamber of the present invention;

[0033] Figure 5 This is a schematic diagram of the structure of the upper electrode and dielectric separator of the present invention;

[0034] Figure 6 This is a schematic diagram of the structure of the semiconductor process chamber of the present invention;

[0035] Figure 7 This is a schematic diagram of the monitoring device structure of the present invention;

[0036] Figure 8 This is a schematic diagram of the ignition experiment results of the present invention;

[0037] Figure 9 This is a schematic diagram of the second ignition experiment result of the present invention. Detailed Implementation

[0038] To better understand the technical solution of this invention, the content of this invention includes, but is not limited to, the specific embodiments described below. Similar technologies and methods should be considered within the scope of protection of this invention. To make the technical problems to be solved, the technical solutions, and advantages of this invention clearer, a detailed description will be provided below in conjunction with the accompanying drawings and specific embodiments.

[0039] It should be understood that the embodiments described in this invention are merely some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0040] First, we will introduce the plasma chamber involved in the relevant technologies.

[0041] like Figure 1 As shown, the prior art employs a plasma chamber. This chamber has an upper electrode composed of a coil 1 and a lower electrode 2 typically mounted on a base. When the chamber has a coil 1 (e.g., in a pre-cleaning chamber), plasma ignition is achieved by applying RF2 power at a frequency of f2 to the lower electrode 2 within the chamber during plasma ignition. During plasma ignition, the coil 1 positioned in the chamber can be powered by an RF1 power source at a frequency of f1 via a first RF power source and a first matching network, or no power may be applied. If the chamber does not have a coil 1, plasma ignition can also be achieved by applying RF1 power at a frequency of f1 to the upper electrode 3 (e.g., in plasma-enhanced chemical vapor deposition (PECVD) and plasma-enhanced atomic layer deposition (PEALD) chambers with a shower head or flow equalizer mounted on the top of the chamber). During plasma ignition, no power is applied to the lower electrode 2, or RF2 power at a frequency of f2 is applied via a second RF power source and a second matching network. The existing technology has the following drawbacks: In some cases, such as the presence of water, polymers, or molecular or polymer residues from other upstream processes on the substrate, volatile substances, or chamber conditioning conditions, the energy that should be applied to the process gas will be applied to these contaminants. Since these contaminants are not easy to ignite and generate plasma, the probability of successful plasma ignition will be significantly reduced, thus making the process impossible.

[0042] The second prior art, based on the first prior art, applies a microwave power (MW) and a third matching network to the upper electrode 3 to achieve plasma ignition by causing electrons to oscillate at high frequencies. This technique uses a relatively expensive microwave power supply, making it costly to operate.

[0043] Therefore, as Figure 3 The diagram shows a semiconductor process chamber according to the present invention. The chamber includes a process cavity for generating plasma. The process cavity includes an upper cover, side walls, and a base disposed inside the process cavity for carrying a wafer to be processed. An upper electrode is disposed below the upper cover, and a lower electrode is disposed on the base. A main ignition device is connected to the upper electrode and / or the lower electrode, and an auxiliary ignition device is connected to the upper electrode or the lower electrode. The chamber also includes a monitoring device disposed on the base.

[0044] The main ignition device is used to provide main ignition energy for generating plasma in the process chamber; the auxiliary ignition device is used to provide auxiliary ignition energy for generating plasma in the process chamber; the monitoring device is used to detect whether the main ignition device and the auxiliary ignition device have successfully ignited.

[0045] Preferably, in the embodiments of the present invention, the main ignition device includes a first ignition branch and / or a second ignition branch. The first ignition branch includes a first radio frequency power supply and a first matching network, wherein the input terminal of the first matching network is connected to the output terminal of the first radio frequency power supply, and the output terminal of the first matching network is connected to the upper electrode. The second ignition branch includes a second radio frequency power supply and a second matching network, wherein the input terminal of the second matching network is connected to the output terminal of the second radio frequency power supply, and the output terminal of the second matching network is connected to the lower electrode. The auxiliary ignition device includes a third radio frequency power supply (i.e., Figure 3 The upper electrode assisted ignition RF and the attached Figure 6 (lower electrode assisted ignition RF) and third matching network (i.e. Figure 3 Matching network 4 and appendix Figure 6 Matching Network The input of the third matching network is connected to the output of the third RF power supply, and the output of the third matching network is connected to the upper electrode or the lower electrode.

[0046] An auxiliary ignition device allows additional radio frequency energy to enter the process cavity, thereby more efficiently exciting the plasma and making the plasma ignition process more controllable and stable. The auxiliary ignition device can apply an adaptive mode if the main ignition process fails on the first run of a wafer, or it can be applied synchronously with the main ignition process.

[0047] Preferably, in the embodiments of the present invention, when the auxiliary ignition device is applied to the upper electrode 3, specifically as follows: Figure 4As shown, the process chamber includes an upper cover 11, a base, and a side wall 12. An upper electrode 3 is disposed below the upper cover 11, and a lower electrode 2 is disposed on the base. When the auxiliary ignition device is connected to the upper electrode 3, a vacuum exists between the upper cover 11 and the side wall 12 of the chamber. The plasma-assisted ignition radio frequency energy output from the matching network 4 is transmitted to the radio frequency access conductor 9 (made of commonly used radio frequency transmission materials such as copper and stainless steel) through the radio frequency transmission cable 16 (such as a coaxial cable), and is connected to the radio frequency access plate 10 made of metal (such as copper and stainless steel). The radio frequency access plate 10 includes a base plate arranged concentrically with the chamber and an annular plane erected on the outer edge of the base plate. The radio frequency access plate 10 is made of metal, thus forming an electrode plate. The output end of the matching network 4 is connected to the upper end of the conductor 9, and the lower end of the conductor 9 is connected to the base plate of the radio frequency access plate 10. The arrangement of the radio frequency access plate 10 ensures that the radio frequency energy accessed by the conductor 9 is evenly distributed on the upper electrode 3.

[0048] A groove is provided on the outer surface of the sidewall 12, and a plurality of auxiliary ignition electrodes 13 are disposed in the groove. A dielectric cylinder 15 concentric with the sidewall is provided on the inner surface, and the upper electrode 3 is provided on the upper end surface of the dielectric cylinder 15. The top surface of the sidewall 12 is connected to the upper cover 11. The dielectric material of the sidewall 12 includes materials such as ceramic. Ignition auxiliary electrodes 13 made of metal are embedded in the groove on the outer surface of the sidewall 12. The upper end of the ignition auxiliary electrode 13 is opposite to the vertical annular plane of the RF access board 10, and the annular plane is opposite to at least a part of the ignition auxiliary electrode 13 and is spaced apart. The thickness of the dielectric material between them is 1 to 5 mm. The ignition auxiliary electrodes 13 are located at both ends of several circumferential diameters of the sidewall 2 and are evenly distributed on the circumference of the outer surface of the sidewall 2. The number of ignition auxiliary electrodes 13 can be 2, 4, 6, etc., i.e., arranged in even numbers. Figure 4 The case where the quantity is 2 is displayed.

[0049] When the ignition power of the main and auxiliary ignition devices is simultaneously applied to the upper electrode 3 in the process chamber, if the upper electrode 3 [including but not limited to the upper electrode plate of the CCP (capacitively coupled plasma) chamber, the shower head, the flow equalization plate, etc.] is made of metal, a dielectric separator 14 needs to be set between the upper end face of the dielectric cylinder 15 and the upper electrode 3 to avoid substrate defects caused by sparking, hollow cathode discharge, etc. The RF access board 10, the upper electrode 3, and the dielectric separator 14 are all placed on the upper end face of the dielectric cylinder 15, which is concentric with the side wall 12. The dielectric cylinder 15 is made of quartz or Al2O3 ceramic, with a thickness of 2~5mm, and serves as a support. Its use of dielectric material allows the RF energy of the ignition auxiliary electrode 13 to enter the chamber.

[0050] The power generated by the main and auxiliary ignition devices enters the process chamber through the upper electrode 3 on the upper cover 11 inside the process chamber. This power is then conducted through a displacement current (which is used when radio frequency energy passes through a dielectric material) through the dielectric between the upper end of the ignition auxiliary electrode 13 and the outer edge of the radio frequency access plate 10, forming a vertical annular plane. This power is then transferred to several plasma ignition auxiliary electrodes 13 arranged around the outer side of the sidewall 2, and then from the sidewall 2 to the process gas inside the chamber. This increases the effective ignition area of ​​the process gas near the upper electrode 3, allowing more energy to enter the process gas and thus enabling stable plasma ignition. The several auxiliary ignition electrodes 13 increase the contact area between the radio frequency energy and the process gas inside the chamber. Without the auxiliary ignition electrodes 13, the radio frequency ignition energy is concentrated below the upper electrode 3. With the auxiliary ignition electrodes 13, the radio frequency ignition energy is applied to the sidewall of the chamber. Because the effective ignition area is increased, more radio frequency energy enters the process gas. This method of transferring the auxiliary RF power applied to the chamber cover to the auxiliary ignition electrode on the inner wall of the process chamber through displacement current can replace the use of coaxial cables or RF conductive conductors, greatly simplifying the design of RF components and improving the stability of the RF system.

[0051] Preferably, the embodiments of the present invention, such as Figure 5 As shown, the dielectric separator 14 can be made into a cover shape. The upper electrode 3 inside the process chamber is a showerhead, which can be used as a gas distribution plate. The dielectric separator 14 and the upper electrode 3 are provided with the same number, arrangement and size of air inlets. The position of the air inlets of the dielectric separator 14 is consistent with that of the upper electrode 3 inside the chamber. Its material can be quartz or Al2O3 ceramic, and the thickness of the dielectric separator 14 is between 3mm and 5mm. Figure 5 The arrangement, size, and number of air inlets shown are only one implementation. Any other symmetrical arrangement of air inlets centered on the center of the upper electrode 3 in the process chamber can also be used. The air inlet pipe of the upper electrode 3 in the chamber can adopt a variety of industry-known access methods, which are well known in the industry and will not be elaborated further.

[0052] Preferably, the monitoring device in the embodiment of the present invention is used to monitor the ignition status of plasma in the process chamber. The monitoring device includes a current sensor, a processing circuit, and a controller connected in sequence. The current sensor is embedded on the lower surface of the edge region of the base and is used to detect the plasma discharge current and output the detected discharge current to the processing circuit. The processing circuit is used to limit, filter, and sample the discharge current before outputting it to the controller. The controller is used to determine whether ignition is successful based on the received current.

[0053] Specifically, the present invention installs a current sensor 5 on the base to monitor the change of plasma current before and after the ignition of the main ignition device and / or auxiliary ignition device. During the plasma ignition stage of the process, it monitors whether the plasma discharge current flowing through the current sensor 5 is greater than the set threshold and decides whether to apply auxiliary ignition RF power to the lower electrode 2 of the chamber or the upper electrode 3 of the chamber.

[0054] Specifically, the installation location of the current sensor 5 is as follows: Figure 6 As shown, its installation method involves embedding it below the outer edge of the lower surface of the base, preventing it from being directly bombarded by plasma, while its sensing part is in contact with the plasma. The working principle of this current sensor 5 is as follows: Before ignition by the main and auxiliary ignition devices, the current density reaching the substrate surface is close to 0. After plasma ignition, due to the generation of electron and ion currents by plasma discharge, the current density reaching the substrate surface is much greater than 0. If the current density detected by the current sensor 5 exceeds a threshold (e.g., 0.5 A / m²), it will detect the plasma. 2 The specific value can be determined by the actual discharge current density after plasma ignition obtained during debugging. This threshold can be set to any value between 10% and 90% of the discharge current density after normal plasma ignition, in which case ignition is considered successful. The current sensor 5 monitors the state of the plasma within the chamber throughout the plasma ignition process. In adaptive mode (i.e., monitoring during the process ignition), if the current density monitored by the current sensor 5 is still lower than the threshold at the end of the main ignition process on a wafer, the ignition process is automatically repeated, and the third RF power supply of the auxiliary ignition device is activated, inputting the auxiliary ignition RF power into the chamber to assist ignition. The number of re-ignition attempts can be set to an upper limit in the semiconductor equipment software. If ignition fails after reaching this upper limit, the process is interrupted and an alarm is triggered. The power of the auxiliary ignition device can also be applied synchronously with the ignition process of the main ignition device. In adaptive mode, only the main ignition device is applied during the first ignition, and the auxiliary ignition device is not applied. If ignition fails during this process, the auxiliary ignition device is activated during repeated ignition attempts.

[0055] Preferably, the current sensor 5 in the embodiment of the present invention has the following structure: Figure 7As shown. The current sensor 5 includes a silicon rod 6 covered with dielectric material, a coil 8, and a cap 7. The coil 8 is wrapped around the silicon rod 6. One end of the silicon rod 6 is grounded, and the other end is used to contact the plasma. To prevent the plasma from entering the current sensor 5 and etching its internal components, its plasma contact surface is sealed with a ceramic cap 7. The silicon rod 6, located at the center of the dielectric material, connects the plasma and ground, so that the plasma only bombards the dielectric material surface of the current sensor 5, preventing contamination of the chamber. In addition, the current sensor 5 is located below the substrate surface, so the byproducts generated after being bombarded by the plasma can be directly removed by the vacuum pump below the chamber, avoiding them from falling onto the wafer surface and affecting the process. Since the silicon rod 6 has a high resistance and the current flowing through it is small, multiple turns of the coil 8 can be used to amplify and collect the current.

[0056] Taking adaptive mode as an example, after the main ignition device ignites, the discharge current flows into the ground through the silicon rod 6 of the current sensor 5. The magnetic flux generated on the silicon rod 6 induces a current in the coil 8 surrounding the silicon rod. Depending on the magnitude of the plasma discharge current density, a current limiting circuit or a current amplification circuit can be connected to the circuit connected to the lead wire of the coil 8. Figure 7 (Only the current limiting circuit is shown in the diagram) to ensure that the actual current entering the monitoring terminal is within a safe and measurable range. Since the effective discharge current in plasma processing is a positive ion unidirectional current, a low-pass filter is connected after the current limiting circuit or current amplification circuit to filter out high-frequency signals and their harmonics from the RF power supply. This filter can be a Butterworth or Chebyshev filter, or other types of filters; this is well-known in the industry and will not be elaborated upon here. The filtered signal enters the connected ammeter or sampling circuit and is then input to the controller for processing. The controller can be an existing laptop or desktop computer. The aforementioned current limiting circuit or current amplifier, filter, and ammeter or sampling circuit constitute the processing circuit, used for current limiting, filtering, and sampling of the current drawn from coil 8.

[0057] Preferably, embodiments of the present invention also provide an ignition method for a semiconductor process chamber, the method being implemented using the semiconductor process chamber described in the present invention, and used in a cleaning process, comprising the following steps:

[0058] (1) Process gas is introduced into the chamber at the start of the process;

[0059] (2) After the air pressure in the chamber stabilizes, the main ignition device applies radio frequency power to the upper or lower electrode; if there is a coil surrounding the side wall of the chamber, the radio frequency power can be applied to the coil at this time. For the first ignition, the auxiliary ignition device can be activated to apply auxiliary ignition power to the upper or lower electrode, or the auxiliary ignition device can be not activated. If this step is a subsequent repeated ignition after ignition failure, the auxiliary ignition device is activated;

[0060] (3) The radio frequency energy generated by ignition is applied to the process gas through the upper or lower electrode, ionizing the process gas into plasma;

[0061] (4) The discharge current of the plasma enters the current monitoring sensor under the base, and after being processed by current limiting and filtering, it enters the ammeter and sampling circuit. The sampled current data is then input to the controller.

[0062] (5) After ignition starts for a period of time, such as 1~3s, the controller software starts to monitor the current density of the current sensor. If the monitored current density is greater than or equal to the set threshold, the ignition is successful and the subsequent process begins; if the monitored current density is less than the set threshold, the ignition fails and steps (2)-(5) are repeated to start the ignition process.

[0063] Preferably, in the embodiments of the present invention, at the end of the ignition process, the current density measured by the monitoring device is compared with a preset current density threshold. If it exceeds the preset threshold, the ignition is successful, and there is no need to start the auxiliary ignition device. The RF power supply of the auxiliary ignition device does not output power. If the measured current density is less than the preset threshold, the ignition fails. The main ignition device ignition process is repeated while the auxiliary ignition device of the present invention is started to assist in the ignition RF power, thus promoting the successful plasma ignition.

[0064] Preferably, the embodiments of the present invention further include interrupting the process and alarming when ignition fails after the number of ignition attempts reaches the set upper limit; if ignition fails after the number of ignition attempts reaches or exceeds the specified upper limit, the ignition operation must be interrupted and an alarm must be triggered in a timely manner.

[0065] Because the area near the process chamber cover is less affected by contaminants generated on the substrate surface, the RF energy generated by the auxiliary ignition device can be applied to the process gas at a smaller skin depth. Therefore, the RF frequency of the auxiliary ignition device applied to the upper electrode 3 can be higher than the frequency of the main ignition device's RF power supply (higher frequency means smaller skin depth, more intense electron vibration, and a larger collision cross-section with the neutral gas, which is more conducive to ignition), resulting in a higher plasma density during ignition and less bombardment of the chamber cover. When the auxiliary ignition RF power of the auxiliary ignition device is applied to the lower electrode 2, due to the influence of contaminants generated on the substrate surface, the auxiliary ignition RF frequency applied to the lower electrode 2 can be lower than the frequency of the main ignition device's RF power supply, resulting in a deeper auxiliary ignition RF feed-in depth (lower frequency means larger skin depth), which is beneficial for applying energy to the process gas. In other words, the power of the auxiliary ignition device applied to the upper electrode 3 can be higher than the power of the main ignition device, and the power of the auxiliary ignition device applied to the lower electrode 2 can be lower than the power of the main ignition device.

[0066] The plasma ignition experiment conducted within the process cavity using the present invention yielded the following results: Figures 8-9 As shown in the figure, the ignition success rate is only 40% without an auxiliary ignition device, while the chamber ignition success rate is 100% with an auxiliary ignition device.

[0067] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0068] The foregoing description illustrates and describes several preferred embodiments of the present invention. However, as previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A semiconductor process chamber, the chamber comprising a process cavity for generating plasma, characterized in that, The process chamber includes a top cover, side walls, and a base disposed inside the process chamber for holding the wafer to be processed; An upper electrode is provided below the upper cover, a lower electrode is provided on the base, a main ignition device is connected to the upper electrode and / or the lower electrode, an auxiliary ignition device is connected to the upper electrode or the lower electrode, and a monitoring device is also provided on the base. The main ignition device is used to provide main ignition energy for generating plasma in the process chamber; The auxiliary ignition device is used to provide auxiliary ignition energy for generating plasma in the process chamber; A groove is provided on the outer side surface of the sidewall, and a plurality of ignition auxiliary electrodes are disposed in the groove; a dielectric cylinder concentric with the sidewall is provided on the inner side surface of the sidewall. The monitoring device is used to detect whether the main ignition device and the auxiliary ignition device have successfully ignited.

2. The semiconductor process chamber according to claim 1, characterized in that, The upper electrode includes one or a combination of a coil, an electrode plate, a gas distribution plate, and a flow equalization plate.

3. The semiconductor process chamber according to claim 2, characterized in that, The main ignition device includes a first ignition branch and / or a second ignition branch. The first ignition branch includes a first radio frequency power supply and a first matching network, wherein the input terminal of the first matching network is connected to the output terminal of the first radio frequency power supply, and the output terminal of the first matching network is connected to the upper electrode. The second ignition branch includes a second radio frequency power supply and a second matching network, wherein the input terminal of the second matching network is connected to the output terminal of the second radio frequency power supply, and the output terminal of the second matching network is connected to the lower electrode.

4. The semiconductor process chamber according to claim 2, characterized in that, The auxiliary ignition device includes a third radio frequency power supply and a third matching network. The input terminal of the third matching network is connected to the output terminal of the third radio frequency power supply, and the output terminal of the third matching network is connected to the upper electrode or the lower electrode.

5. The semiconductor process chamber according to claim 4, characterized in that, An RF access board is provided between the upper electrode and the upper cover. The RF access board includes a base plate that is co-centered with the process cavity and an annular plane that rises from the edge of the base plate. The annular plane is opposite to and spaced apart from at least a portion of the ignition auxiliary electrode.

6. The semiconductor process chamber according to claim 5, characterized in that, A conductor is provided between the radio frequency access board and the auxiliary ignition device. One end of the conductor is connected to the base plate, and the other end of the conductor is connected to the output terminal of the third matching network.

7. The semiconductor process chamber according to claim 1, characterized in that, A dielectric separator is provided between the upper end face of the dielectric cylinder and the upper electrode.

8. The semiconductor process chamber according to claim 7, characterized in that, When the upper electrode is a gas distribution plate, the dielectric partition and the gas distribution plate are provided with a number of air inlets of the same size and corresponding to each other.

9. The semiconductor process chamber according to claim 1, characterized in that, The monitoring device includes a current sensor, a processing circuit, and a controller connected in sequence. The current sensor is embedded on the lower surface of the edge region of the base and is used to detect the plasma discharge current and output the detected discharge current to the processing circuit. The processing circuit is used to limit, filter, and sample the discharge current before outputting it to the controller. The controller is used to determine whether ignition is successful based on the received current.

10. The semiconductor process chamber according to claim 9, characterized in that, The current sensor includes a silicon rod covered with a dielectric material, a coil, and a cap post, wherein the coil is wound around the silicon rod, and the cap post seals the dielectric surface of the current sensor that is in contact with the plasma.

11. An ignition method for a semiconductor process chamber, characterized in that, The method is implemented using the semiconductor process chamber according to any one of claims 1-10, and includes the following steps: (1) Introduce process gas into the chamber; (2) Ignition is performed after the air pressure in the chamber stabilizes. If it is the first ignition, the main ignition device is started and the auxiliary ignition device is not required. If it is a repeated ignition, the main ignition device and the auxiliary ignition device are started at the same time. (3) Apply the radio frequency energy of the main ignition device or the main and auxiliary ignition devices to the process gas to ionize the process gas into plasma; (4) The discharge current of the plasma is monitored using a monitoring device; (5) After a certain period of time after ignition, if the monitored current density is greater than or equal to the set threshold, the ignition is successful and the subsequent process begins; if the monitored current density is less than the set threshold, the ignition fails and steps (2)-(5) are repeated.

12. The ignition method for a semiconductor process chamber according to claim 11, characterized in that, It also includes monitoring the number of ignition attempts. If ignition fails after reaching the set upper limit, the process is interrupted and an alarm is triggered.

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