Atomic layer etching method and equipment

Abstract

This invention discloses an atomic layer etching method and apparatus. The atomic layer etching method includes: multiple sequential cycles; each cycle includes: introducing a deposition gas and an etching gas into a reaction chamber; applying excitation power to ionize the deposition gas into a first plasma and the etching gas into a second plasma; wherein the first plasma modifies the atoms on the substrate surface within the reaction chamber to form a modified layer; stopping the introduction of the deposition gas and, after a first preset time, starting to apply bias power to control the second plasma to etch the modified layer; and stopping the application of bias power; wherein the first preset time allows at least the unadsorbed first plasma after the formation of the modified layer to be discharged. This invention can meet the etching precision requirements of atomic layer etching processes and improve the controllability of the etching process.

Description

[Technical Field]

[0001] This invention relates to the field of semiconductor fabrication technology, and in particular to an atomic layer etching method and apparatus. [Previous Technology]

[0002] In the semiconductor fabrication process, as feature size shrinks and patterns become more refined, the requirements for etching processes are further increased, and atomic layer etching (ALE) technology has emerged as a result.

[0003] Atomic layer etching is a technique that uses a self-limiting reaction to remove atomic layers from a substrate. It typically involves multiple cycles, and each cycle generally includes a modification step and an etching step. In the modification step, a deposition gas is introduced, and the deposition gas combines only with one or more atoms on the substrate surface, thereby changing the chemical properties of the atoms on the substrate surface. In the etching step, an etching gas is introduced and ionized, and the plasma generated by the ionization bombards the atoms on the modified substrate surface, causing the one or more atoms on the modified substrate surface to desorb, thereby achieving atomic layer etching.

[0004] However, existing equipment has a significant gap between the gas response speed and the requirements of the etching process in atomic layer etching (ALE). The delayed gas response and gas exchange efficiency affect the process accuracy of ALE, thus limiting the accurate transfer of patterns and precise control of dimensions. Large loading effects can easily occur between different patterns. Furthermore, due to the relatively long length of the gas pipeline connecting the gas source and the reaction chamber, there is a time difference between the gas supply command issued by the controller and the actual arrival of the gas in the reaction chamber. This results in a phase difference between the gas response speed and the RF power output, causing a prolonged mixing process between the modification and etching processes in ALE. The delayed gas response and gas exchange efficiency further affect the process accuracy of ALE. Therefore, it is necessary to adjust the atomic layer etching method and equipment. [Summary of the Invention]

[0005] The purpose of this invention is to provide an atomic layer etching method and apparatus, which can avoid the adsorption modification process in atomic layer etching from mixing with the process gas used in the etching process for a long time, thereby meeting the requirements of atomic layer etching process for etching accuracy and improving the control capability of etching process.

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

[0007] An atomic layer etching method includes: a plurality of sequentially performed cycles; each cycle includes: introducing a deposition gas and an etching gas into a reaction chamber; applying an excitation power to ionize the deposition gas into a first plasma and the etching gas into a second plasma; wherein the first plasma modifies the atoms on the surface of a substrate in the reaction chamber to form a modified layer; stopping the introduction of the deposition gas and, after a first preset time, starting to apply a bias power to control the second plasma to etch the modified layer; and stopping the application of the bias power; wherein the first preset time allows at least the first plasma that was not adsorbed after the formation of the modified layer to be discharged.

[0008] Optionally, in the first cycle of the plurality of cycles, the excitation power is applied after a second preset time following the introduction of the deposition gas; in the non-first cycles of the plurality of cycles, the excitation power is continuously applied.

[0009] Optionally, after the excitation power is applied, the excitation power has a first power value within the first preset time period, and the excitation power has a second power value outside the first preset time period, wherein the first power value is 20% to 50% of the second power value.

[0010] Optionally, the second preset duration allows the deposited gas to enter the reaction chamber from the gas source via a gas pipeline.

[0011] Optionally, if the absolute value of the change in the light intensity of the first plasma after normalization within a set time does not exceed a set threshold, then the first plasma is in a steady state, and the average value of the light intensity of the first plasma within the set time is the steady state intensity.

[0012] After the deposition gas is stopped, if the light intensity of the first plasma is less than 10% of its steady-state intensity, the first plasma that was not adsorbed after the formation of the modified layer is discharged.

[0013] Optionally, the set duration is 0 seconds to 5 seconds, and the set threshold is 0 to 5%.

[0014] Optionally, each of the cycles further includes: after stopping the application of the bias power, adjusting the process parameters within a first transition period.

[0015] Optionally, the process parameters include the flow rate of the etching gas and the pressure of the reaction chamber.

[0016] Optionally, the excitation power is higher than the bias power.

[0017] Optionally, the excitation power is high frequency and the bias power is low frequency.

[0018] Optionally, the deposition gas is CxHyFz gas, CaFb gas or CmHn gas, wherein x, y, z, a, b, m and n are not 0.

[0019] Optionally, when the deposition gas is CxHyFz gas or CaFb gas, the etching gas is argon or krypton; when the deposition gas is CmHn gas, the etching gas includes one of argon and krypton as well as an oxygen-containing gas.

[0020] On the other hand, the present invention also provides an atomic layer etching method, comprising: a plurality of cycles performed sequentially; each cycle comprising: introducing a deposition gas and an etching gas into a reaction chamber; applying an excitation power to ionize the deposition gas into a first plasma and the etching gas into a second plasma; wherein the first plasma modifies the atoms on the surface of the substrate in the reaction chamber to form a modified layer; stopping the introduction of the deposition gas, and after a third preset time, starting to apply a bias power to control the second plasma to etch the modified layer; and stopping the application of the bias power; wherein the third preset time is longer than the time required to evacuate the first plasma that has not been adsorbed after the formation of the modified layer, thereby delaying the etching of the modified layer; and the third preset time includes a second transition time and a lag time; adjusting process parameters during the second transition time, waiting for the etching of the modified layer during the lag time; and evacuating the deposition gas that has not been adsorbed after the formation of the modified layer until it is emptied during both the second transition time and the lag time.

[0021] Optionally, the second transition duration is 1 second to 2 seconds.

[0022] Optionally, the lag time is 100 milliseconds to 2 seconds.

[0023] In another aspect, the present invention also provides an atomic layer etching apparatus for implementing the atomic layer etching method as described above; the atomic layer etching apparatus includes: a reaction chamber; an air inlet device disposed at the top inside the reaction chamber for introducing deposition gas and etching gas into the reaction chamber; a base disposed at the bottom inside the reaction chamber for supporting a substrate; a first radio frequency source for outputting excitation power; a second radio frequency source for outputting bias power; and a controller electrically connected to the first radio frequency source and the second radio frequency source for controlling the first radio frequency source to start applying excitation power to the reaction chamber and stop applying the excitation power, and also for controlling the second radio frequency source to start applying bias power to the reaction chamber and stop applying the bias power.

[0024] Optionally, the atomic layer etching apparatus further includes: a light intensity detection device, disposed inside the reaction chamber and electrically connected to the controller, for detecting the light intensity of the first plasma and sending it to the controller.

[0025] The present invention has at least one of the following advantages compared with the prior art:

[0026] The present invention provides an atomic layer etching method and apparatus. The atomic layer etching method includes multiple sequential cycles, and each cycle includes: introducing a deposition gas and an etching gas into a reaction chamber; then ionizing the deposition gas into a first plasma and the etching gas into a second plasma by applying excitation power, wherein the first plasma modifies a single or multiple atomic layer on the substrate surface in the reaction chamber to form a modified layer; then stopping the introduction of the deposition gas, and after a first preset time, starting to apply bias power to control the second plasma to etch the modified layer. The first preset time allows at least the first plasma that was not adsorbed after the formation of the modified layer to be emptied, so that there is no first plasma in the reaction chamber when the bias power is applied. This avoids the first plasma and the second plasma mixing and forming a highly reactive mixed gas when the bias power is applied, which could cause over-etching of the substrate, thereby meeting the etching precision requirements of the atomic layer etching process and improving the control capability of the etching process.

[0027] In this invention, bias power can also be applied after the deposition gas is stopped and a third preset time has elapsed. The third preset time is longer than the time required to drain the first plasma that has not been adsorbed after the formation of the modified layer, thereby delaying the etching step. The third preset time includes a second transition time and a lag time. During the second transition time, the process parameters are adjusted, and during the lag time, the modified layer is etched. The setting of the lag time is beneficial for precise and independent control of the etching process, thereby achieving precise control of the pattern and size on the substrate, and thus meeting the process requirement of very small etching amount. In addition, by reasonably adjusting the relationship between the second transition time and the lag time, the cycle of a single cycle can be effectively shortened, thereby effectively improving the efficiency of atomic layer etching.

[0028] Compared with the prior art, which simultaneously performs the operation of turning on the gas source and applying the excitation power, the present invention applies the excitation power only after the deposited gas has completely entered the reaction chamber in the first cycle. That is, the time of turning on the gas source and the time of applying the excitation power are separated by a second preset time. This can not only accurately control the adsorption modification process, but also avoid over-etching of the substrate and damage to other components in the reaction chamber caused by applying the excitation power in advance.

[0029] After the bias power is stopped, the process parameters are adjusted within the first transition time so that the process parameters meet the process requirements of the next cycle, thereby effectively improving the efficiency of atomic layer etching.

Implementation Method

[0031] The atomic layer etching method and apparatus proposed in this invention will be further described in detail below with reference to the drawings and specific embodiments. The advantages and features of this invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, only for the purpose of conveniently and clearly illustrating the embodiments of this invention. Please refer to the drawings to make the objectives, features, and advantages of this invention more apparent and understandable. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and objectives achieved by this invention, should still fall within the scope of the technical content disclosed in this invention.

[0032] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus 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 apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0033] Example 1

[0034] Referring to Figures 1-3, this embodiment provides an atomic layer etching method for etching a substrate in a reaction chamber; the atomic layer etching method includes: multiple cycles performed sequentially; each cycle includes: step S1, introducing a deposition gas and an etching gas into the reaction chamber; step S2, applying excitation power to ionize the deposition gas into a first plasma and the etching gas into a second plasma; and the first plasma modifies the atoms on the surface of the substrate in the reaction chamber to form a modified layer; step S3, stopping the introduction of the deposition gas, and after a first preset time, starting to apply bias power to control the second plasma to bombard and etch the modified layer; and step S4, stopping the application of the bias power; wherein, the first preset time allows at least the first plasma that was not adsorbed after the formation of the modified layer to be discharged.

[0035] Specifically, the deposition gas and the etching gas are stored in different gas sources, and each gas source is connected to the reaction chamber through a gas pipeline to deliver the deposition gas and the etching gas into the reaction chamber. Under the action of the excitation power, the deposition gas is ionized into the first plasma, and the first plasma can undergo a deposition reaction with the atoms on the substrate surface, thereby modifying the single layer or multiple layers of atoms on the substrate surface and forming the modified layer. This process (including steps S1 and S2) can be called the adsorption modification process.

[0036] The etching gas is ionized into the second plasma under the excitation power. Further, under the bias power, the second plasma is accelerated and guided onto the substrate and bombards the modified layer to etch the modified layer, thereby etching the substrate. This process (including steps S3 and S4) can be referred to as the etching process. Optionally, the excitation power is higher than the bias power, so that the excitation power serves as the source power for exciting the plasma. Optionally, the excitation power is high-frequency, such as 13.56MHz, 27MHz, or 60MHz; the bias power is low-frequency, such as less than or equal to 400kHz. Furthermore, the deposition gas and etching gas will differ depending on the target of atomic layer etching on the substrate; for example, when the target of atomic layer etching on the substrate is silicon nitride, the deposition gas is CxHyFz gas (where x, y, and z are not 0), preferably CH3F gas, and the etching gas is argon or krypton. When the target of atomic layer etching on the substrate is silicon oxide, the deposition gas is CaFb gas (where a and b are not 0), preferably C4F6 gas; the etching gas is argon or krypton. When the target of atomic layer etching on the substrate is a carbon film, the deposition gas is CmHn gas (where m and n are not 0), preferably CH4 gas; the etching gas includes not only one of argon and krypton, but also an oxygen-containing gas, preferably oxygen, but the present invention is not limited thereto.

[0037] In this embodiment, after the modified layer is formed on the substrate, the deposition gas is stopped being introduced into the reaction chamber, and the bias power is applied only after the first preset time has elapsed since the deposition gas was stopped. During the first preset time, a vacuum pump can be used to vent the first plasma that was not adsorbed after the formation of the modified layer, so that when the bias power is applied, there is no first plasma in the reaction chamber and only the second plasma or a mixture of the second plasma and the etching gas exists. This avoids the mixing of the first plasma and the second plasma when the bias power is applied, thereby avoiding a long period of mixing between the adsorption modification process in atomic layer etching and the process gas used in the etching process. This also avoids the formation of a highly reactive mixed gas in the reaction chamber, which would cause over-etching of the substrate, thus meeting the requirements of the atomic layer etching process for etching accuracy and improving the control capability of the etching process.

[0038] Furthermore, in this embodiment, a light intensity detection device is provided in the reaction chamber. The light intensity detection device can be used to detect the light intensity of the first plasma in the reaction chamber to accurately determine whether the first plasma has been emptied. Specifically, as shown in Figure 3, after the deposition gas is introduced, if the absolute value of the normalized change in the light intensity of the first plasma within a set time does not exceed a set threshold, then the first plasma is in a steady state, and the average value of the light intensity of the first plasma within the set time is its steady-state intensity. Further, after the deposition gas is stopped, if the light intensity of the first plasma is detected to be less than 10% of its steady-state intensity, then it is considered that the first plasma that has not been adsorbed after the modified layer has been emptied. More specifically, the first preset time is related to factors such as the pumping rate and the volume of the reaction chamber. In some embodiments, the value of the first preset time can also be determined by multiple light intensity detections of the first plasma or by emptying experiments of the first plasma. Optionally, the first preset time is set to 1s~3s; preferably, the first preset time is set to 2s. Optionally, the set duration is 0s to 5s, and the set threshold is 0 to 5%; preferably, the set duration is 2s, and the set threshold is 2%. Optionally, the light intensity detection device is an OES spectrometer, but the present invention is not limited thereto.

[0039] Please continue to refer to Figure 2. In the first cycle of the plurality of cycles, that is, at the beginning stage of each process, the excitation power is applied after the deposition gas is introduced and a second preset time T1 has elapsed. In the non-first cycle of the plurality of cycles (e.g., the second cycle), the excitation power is continuously applied.

[0040] Specifically, the second preset duration T1 allows the deposition gas to enter the reaction chamber from the gas source via the gas pipeline, ensuring that the deposition gas is fully inside the reaction chamber before applying the excitation power to adsorb and modify the atoms on the substrate surface. Optionally, the second preset duration T1 is exactly the time required for the deposition gas to fully enter the reaction chamber from the gas source; and the second preset duration T1 is usually related to factors such as the length of the gas pipeline and the flow rate of the deposition gas. In some embodiments, the light intensity detection device can also be used to detect the light intensity of the deposition gas in the reaction chamber. When the light intensity signal of the deposition gas is detected, it indicates that the deposition gas has fully entered the reaction chamber from the gas source via the gas pipeline; as shown in Figure 3, after the second preset duration T1, if the light intensity signal of the deposition gas in the reaction chamber is detected at time A, then the excitation power is applied and the first plasma is excited. Furthermore, the value of the second preset duration can be determined by repeatedly detecting the light intensity of the deposition gas or by conducting experiments to introduce the deposition gas. Optionally, the second preset duration T1 is set to 1s to 3s; preferably, the second preset duration T1 is set to 2s, but the present invention is not limited thereto.

[0041] Specifically, compared with the prior art, which simultaneously performs the operation of turning on the gas source and applying the excitation power, in this embodiment, the excitation power is applied only after the deposited gas has completely entered the reaction chamber in the first cycle. That is, the time of turning on the gas source and the time of applying the excitation power are separated by the second preset time T1. This can not only accurately control the adsorption modification process, but also avoid over-etching of the substrate and damage to other components in the reaction chamber caused by applying the excitation power in advance.

[0042] Specifically, after the excitation power is initially applied, it is continuously applied until multiple cycles are completed. This continuously ionizes the etching gas into the second plasma, preventing the second plasma in the reaction chamber from being interrupted, thus preparing for the etching process. The modified layer can be etched instantly upon the application of the bias power, thereby precisely controlling the etching process and achieving precise control of the pattern and size on the substrate. Optionally, the power value of the subsequently applied excitation power remains unchanged, but this invention is not limited thereto.

[0043] Please continue to refer to Figure 2. Each cycle further includes: step S5, after stopping the application of the bias power, adjusting the process parameters within a first transition time T2 to ensure that the process parameters meet the process requirements of the next cycle, thereby effectively improving the efficiency of atomic layer etching. Optionally, the process parameters include the flow rate of the etching gas and the pressure of the reaction chamber; preferably, during the adsorption modification process, the flow rate of the etching gas is 1~10 sccm, and the pressure of the reaction chamber is 10~50 mtorr; during the etching process, the flow rate of the etching gas is 100~1000 sccm, and the pressure of the reaction chamber is 10~50 mtorr, but the present invention is not limited thereto.

[0044] Example 2

[0045] Referring to Figure 4, the difference between this embodiment and Embodiment 1 is that, after applying the excitation power, the excitation power has a first power value h1 within the first preset time period, and a second power value h2 outside the first preset time period; wherein, the first power value h1 is 20% to 50% of the second power value h2. This can save the electrical energy required to continuously apply the excitation power, maintain the second plasma in the excited state to prevent the second plasma in the reaction chamber from being cut off, and also prevent the excitation power from damaging other components in the reaction chamber. Preferably, the first power value h1 is 30% of the second power value h2. Optionally, the second power value h2 is 100W, and the first power value h1 is 20W to 50W, but the present invention is not limited thereto.

[0046] Example 3

[0047] Referring to Figures 5-6, this embodiment provides an atomic layer etching method, including: multiple cycles performed sequentially; each cycle includes: step S1', introducing a deposition gas and an etching gas into a reaction chamber; step S2', applying excitation power to ionize the deposition gas into a first plasma and the etching gas into a second plasma; and the first plasma modifies a single layer or multiple layers of atoms on the surface of the substrate in the reaction chamber to form a modified layer; step S3', stopping the introduction of the deposition gas, and after a third preset time, starting to apply bias power to control the second plasma to etch the modified layer; and step S4', stopping the application of the bias power.

[0048] The difference from Embodiment 1 is that, in this embodiment, the third preset time is longer than the time required to evacuate the first plasma that was not adsorbed after the formation of the modified layer, so as to delay the etching of the modified layer. The second preset time includes a second transition time T3 and a hysteresis time T4; the process parameters are adjusted within the second transition time T3, and the etching of the modified layer is waited for within the hysteresis time T4; and the deposited gas that was not adsorbed after the formation of the modified layer is pumped out until it is emptied within both the second transition time T3 and the hysteresis time T4.

[0049] Specifically, the hysteresis time T4 belongs to the etching process, equivalent to the first preset time in Embodiment 1; the second transition time T3 is similar to the first transition time T2, belonging neither to the adsorption modification process nor to the etching process, that is, the adsorption modification process and the etching process are separated by the second transition time T3; and the process parameters can be adjusted within the second transition time T3 so that the process parameters meet the process requirements of the etching process, thereby effectively improving the efficiency of atomic layer etching. Optionally, the second transition time is 1s~2s, but the present invention is not limited thereto.

[0050] Specifically, with the continuous miniaturization of semiconductor devices, the process requirements for very small etching amounts (e.g., etching in 5nm, 3nm, or 2nm process technologies) can be achieved by setting the hysteresis duration T4. For example, when etching the modified layer for 0.3s, existing technologies have difficulty achieving such short-duration etching because the hardware lower limit for gas flow control is above 1s (the response time of commonly used MFCs (Mass Flow Controllers) is usually above 1s). Therefore, the 0.3s etching can be achieved by setting the duration of the entire etching process to 1s and setting the hysteresis duration T4 in the etching process to 700ms. Setting the hysteresis duration T4 is beneficial for precise and independent control of the etching process, thereby achieving precise control of the pattern and size on the substrate, and thus meeting the process requirements for very small etching amounts. By reasonably adjusting the relationship between the second transition duration T3 and the hysteresis duration T4, the cycle of a single cycle can also be effectively shortened, thereby effectively improving the efficiency of atomic layer etching. Optionally, the lag time is 100ms to 2s, but the present invention is not limited thereto.

[0051] In this embodiment, the third preset time is longer than the time required to drain the first plasma that was not adsorbed after the formation of the modified layer. Therefore, within the third preset time (including the second transition time T3 and the lag time T4), a vacuum pump can also be used to drain the first plasma that was not adsorbed after the formation of the modified layer. This ensures that when the bias power is applied, there is no first plasma in the reaction chamber and only the second plasma or a mixture of the second plasma and the etching gas exists. This avoids the mixing of the first plasma and the second plasma when the bias power is applied, thereby avoiding a long mixing time between the adsorption modification process in atomic layer etching and the process gas used in the etching process. This also avoids the formation of a highly reactive mixed gas in the reaction chamber, which could cause over-etching of the substrate. This satisfies the requirements of the atomic layer etching process for etching accuracy and improves the control capability of the etching process.

[0052] Further, after stopping the introduction of the deposition gas, the light intensity detection device can also be used to detect the light intensity of the first plasma in the reaction chamber to accurately determine whether the first plasma has been emptied; and after stopping the introduction of the deposition gas, if the light intensity of the first plasma is detected to be less than 10% of its steady-state intensity, then the first plasma that was not adsorbed after the formation of the modified layer is emptied. More specifically, the third preset time is not only related to the pumping rate and the volume of the reaction chamber, but also to the process parameter adjustment rate, the lag time, and other factors. Therefore, the value of the third preset time can be set according to specific process requirements, or determined through multiple emptying experiments of the first plasma, but the present invention is not limited thereto.

[0053] In addition, in this embodiment, each cycle also includes: step S5', after stopping the application of the bias power, adjusting the process parameters within the first transition time T2 so that the process parameters meet the process requirements of the next cycle, thereby effectively improving the efficiency of atomic layer etching.

[0054] Referring to Figure 7, based on the same inventive concept, the present invention also provides an atomic layer etching apparatus for implementing the atomic layer etching method described above; the atomic layer etching apparatus includes: a reaction chamber 110; an air inlet device 120 disposed at the top inside the reaction chamber 110 for introducing deposition gas and etching gas into the reaction chamber; a base 130 disposed at the bottom inside the reaction chamber 110 for supporting the substrate 100; and a first radio frequency source 140 electrically connected to the air inlet device 120 for outputting excitation power. In some other embodiments, the first radio frequency source 140... It can also be electrically connected to the base 130; the second radio frequency source 150, electrically connected to the base 130, is used to output bias power. In some other embodiments, the second radio frequency source 150 can also be electrically connected to the air intake device 120; the controller 160, electrically connected to the first radio frequency source 140 and the second radio frequency source 150, is used to control the first radio frequency source 140 to start applying excitation power to the air intake device 120 and to stop applying the excitation power, and is also used to control the second radio frequency source 150 to start applying bias power to the base 130 and to stop applying the bias power.

[0055] Specifically, the controller 160 can generate a start excitation power application command and a stop excitation power application command and send them to the first radio frequency source 140; after receiving the start excitation power application command, the first radio frequency source 140 applies the excitation power to the air intake device 120 to ionize the deposition gas into the first plasma, thereby adsorbing and modifying the atoms on the surface of the substrate 100 and forming the modified layer, and can also ionize the etching gas into the second plasma; after receiving the stop excitation power application command, the first radio frequency source 140 stops applying the excitation power to the air intake device 120.

[0056] Specifically, the controller 160 can also generate a start bias power application command and a stop bias power application command and send them to the second radio frequency source 150; after receiving the start bias power application command, the second radio frequency source 150 applies the bias power to the base 130 to accelerate and guide the second plasma onto the substrate 100, thereby bombarding and etching the modified layer; after receiving the stop bias power application command, the second radio frequency source 150 stops applying the bias power to the base 130.

[0057] Please continue to refer to Figure 7. The atomic layer etching equipment further includes: a light intensity detection device 170, which is disposed inside the reaction chamber 110 and electrically connected to the controller 160, for detecting the light intensity of the first plasma and sending it to the controller 160.

[0058] Specifically, in one embodiment, in the first cycle of the plurality of cycles, when the light intensity signal of the deposited gas is detected, the controller 160 generates a command to start applying excitation power and sends it to the first radio frequency source 140; after the plurality of cycles are completed, the controller 160 generates a command to stop applying excitation power and sends it to the first radio frequency source 140. In another embodiment, after determining the value of the second preset duration based on multiple experiments of introducing the deposited gas, the value of the second preset duration can also be input into the controller 160; when the second preset duration is reached, the controller 160 generates a command to start applying excitation power and sends it to the first radio frequency source 140, but the present invention is not limited thereto.

[0059] Specifically, in one embodiment, when the light intensity of the first plasma is less than 10% of its steady-state intensity after the deposition gas is stopped, the controller 160 generates the command to start applying bias power and sends it to the second radio frequency source 150.

[0060] In another embodiment, after determining the value of the first preset duration based on multiple first plasma evacuation experiments, the value of the first preset duration can also be input into the controller 160; when the first preset duration is reached, the controller 160 generates the command to start applying bias power and sends it to the second radio frequency source 150.

[0061] In another embodiment, after determining the value of the third preset duration based on process requirements and multiple evacuation experiments of the first plasma, the value of the third preset duration can also be input into the controller 160; when the third preset duration is reached, the controller 160 generates the command to start applying bias power and sends it to the second radio frequency source 150.

[0062] In addition, in some embodiments, the power value of the excitation power can be adjusted by the controller 160. For example, the excitation power can be adjusted to the first power value or the second power value according to process requirements, but the present invention is not limited thereto.

[0063] In summary, the present invention provides an atomic layer etching method and apparatus. The atomic layer etching method includes multiple sequential cycles, and each cycle includes introducing a deposition gas and an etching gas into a reaction chamber; subsequently, by applying excitation power, the deposition gas is ionized into a first plasma and the etching gas is ionized into a second plasma, wherein the first plasma modifies a single or multiple atomic layer on the substrate surface in the reaction chamber to form a modified layer; then, the introduction of the deposition gas is stopped, and after a first preset time, a bias power is applied to control the second plasma to etch the modified layer; finally, the application of the bias power is stopped. The first preset time allows at least the unadsorbed first plasma after the formation of the modified layer to be emptied, so that there is no first plasma in the reaction chamber when the bias power is applied. This avoids the first plasma and the second plasma mixing and forming a highly reactive mixed gas when the bias power is applied, which could cause over-etching of the substrate, thereby meeting the etching precision requirements of the atomic layer etching process and improving the control capability of the etching process. In this invention, bias power can be applied after the deposition gas is stopped and a third preset time has elapsed. The third preset time is longer than the time required to drain the remaining first plasma after the modified layer is formed, thus delaying the etching step. The third preset time includes a second transition time and a lag time. Process parameters are adjusted during the second transition time, and the modified layer is etched during the lag time. The lag time allows for precise and independent control of the etching process, enabling accurate control of the pattern and size on the substrate, thereby meeting the process requirement of very small etching amounts. Furthermore, by reasonably adjusting the relationship between the second transition time and the lag time, the cycle time of a single cycle can be effectively shortened, thereby effectively improving the efficiency of atomic layer etching.

[0064] Although the present invention has been described in detail through the above preferred embodiments, 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. Therefore, the scope of protection of the present invention should be defined by the appended claims. [Simplified Explanation of the Diagram]

[0030] Figure 1 is a flowchart of an atomic layer etching method provided in Embodiment 1 of the present invention; Figure 2 is a timing diagram of an atomic layer etching method provided in Embodiment 1 of the present invention; Figure 3 is a timing diagram of the light intensity of the first plasma in an atomic layer etching method provided in Embodiment 1 of the present invention; Figure 4 is a timing diagram of an atomic layer etching method provided in Embodiment 2 of the present invention; Figure 5 is a flowchart of an atomic layer etching method provided in Embodiment 3 of the present invention; Figure 6 is a timing diagram of an atomic layer etching method provided in Embodiment 3 of the present invention; Figure 7 is a schematic diagram of the structure of an atomic layer etching device provided by the present invention.

Claims

1. An atomic layer etching method, comprising: Multiple loops performed sequentially; Each cycle includes: introducing a deposition gas and an etching gas into a reaction chamber; applying excitation power to ionize the deposition gas into a first plasma and the etching gas into a second plasma; wherein the first plasma modifies the atoms on the substrate surface within the reaction chamber to form a modified layer; stopping the introduction of the deposition gas and, after a first preset time, starting to apply bias power to control the second plasma to etch the modified layer; and stopping the application of the bias power; wherein the first preset time allows at least the first plasma that was not adsorbed after the formation of the modified layer to be emptied.

2. The atomic layer etching method as described in claim 1, wherein, In the first cycle of the plurality of cycles, the excitation power is applied after a second preset time following the introduction of the deposition gas; in the subsequent cycles of the plurality of cycles, the excitation power is continuously applied.

3. The atomic layer etching method as described in claim 1, wherein, After the excitation power is applied, the excitation power has a first power value within the first preset time period, and the excitation power has a second power value outside the first preset time period. The first power value is 20% to 50% of the second power value.

4. The atomic layer etching method as described in claim 2, wherein, The second preset duration allows the deposition gas to enter the reaction chamber from the gas source via the gas pipeline.

5. The atomic layer etching method as described in claim 1, wherein, If the absolute value of the normalized change in the light intensity of the first plasma within a set time period does not exceed a set threshold, then the first plasma is in a steady state, and the average light intensity of the first plasma within the set time period is the steady-state intensity; after the deposition gas is stopped, if the light intensity of the first plasma is less than 10% of its steady-state intensity, then the first plasma that was not adsorbed after the formation of the modified layer is discharged.

6. The atomic layer etching method as described in claim 5, wherein, The set duration is 0 to 5 seconds, and the set threshold is 0 to 5%.

7. The atomic layer etching method as described in claim 1, wherein, Each of the aforementioned cycles further includes: after stopping the application of the bias power, adjusting the process parameters within a first transition period.

8. The atomic layer etching method as described in claim 7, wherein, The process parameters include the flow rate of the etching gas and the pressure of the reaction chamber.

9. The atomic layer etching method as described in claim 1, wherein, The excitation power is higher than the bias power.

10. The atomic layer etching method as described in claim 9, wherein, The excitation power is high frequency, and the bias power is low frequency.

11. The atomic layer etching method as described in claim 1, wherein, The deposition gas is CxHyFz gas, CaFb gas, or CmHn gas, wherein x, y, z, a, b, m, and n are not 0.

12. The atomic layer etching method as described in claim 11, wherein, When the deposition gas is CxHyFz gas or CaFb gas, the etching gas is argon or krypton gas; when the deposition gas is CmHn gas, the etching gas includes one of argon and krypton gas as well as an oxygen-containing gas.

13. An atomic layer etching method, comprising: Multiple loops performed sequentially; Each cycle includes: introducing a deposition gas and an etching gas into a reaction chamber; applying excitation power to ionize the deposition gas into a first plasma and the etching gas into a second plasma; wherein the first plasma modifies the atoms on the substrate surface within the reaction chamber to form a modified layer; stopping the introduction of the deposition gas and, after a third preset time, starting to apply bias power to control the second plasma to etch the modified layer; and stopping the application of the bias power; wherein the third preset time is longer than the time required to evacuate the first plasma that has not been adsorbed after the formation of the modified layer, thereby delaying the etching of the modified layer; and the third preset time includes a second transition time and a lag time; adjusting process parameters during the second transition time, waiting for the etching of the modified layer during the lag time; and evacuating the deposition gas that has not been adsorbed after the formation of the modified layer until it is emptied during both the second transition time and the lag time.

14. The atomic layer etching method as described in claim 13, wherein, The second transition duration is 1 to 2 seconds.

15. The atomic layer etching method as described in claim 13, wherein, The lag time is 100 milliseconds to 2 seconds.

16. An atomic layer etching apparatus for implementing the atomic layer etching method as described in claim 1 or 13; wherein, The atomic layer etching apparatus includes: a reaction chamber; an inlet device disposed at the top inside the reaction chamber for introducing deposition gas and etching gas into the reaction chamber; a base disposed at the bottom inside the reaction chamber for supporting a substrate; a first radio frequency (RF) source for outputting excitation power; a second RF source for outputting bias power; and a controller electrically connected to the first and second RF sources for controlling the first RF source to start applying excitation power to the reaction chamber and stop applying the excitation power, and also for controlling the second RF source to start applying bias power to the reaction chamber and stop applying the bias power.

17. The atomic layer etching apparatus as claimed in claim 16, further comprising: A light intensity detection device is disposed inside the reaction chamber and electrically connected to the controller, used to detect the light intensity of the first plasma and send it to the controller.

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