Processing time prediction method and system of plasma etching cavity and maintenance method

Abstract

The invention provides a processing time prediction method, system and maintenance method for a plasma etching cavity, and the method comprises the steps: obtaining the consumption rate of at least one position of the edge of a test control wafer which is made of the same or similar material with an edge ring under a new process through an experiment, and taking the consumption rate as the consumption rate of the corresponding position of the edge ring under the new process; therefore, the processing time of the plasma etching cavity under the new process can be estimated according to the MTBC of the plasma etching cavity under the existing process, the consumption rate of the corresponding position of the edge ring and the consumption rate of the corresponding position of the edge ring under the new process. According to the invention, the processing time of the plasma etching cavity under the new process can be evaluated relatively timely and accurately at a low cost, so that the risk caused by introduction of the new process is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to a method, system and maintenance method for predicting processing time of a plasma etching chamber. Background Art

[0002] Plasma etching is one of the commonly used etching methods in the etching process of semiconductor integrated circuit manufacturing technology. Please refer to Figure 1 The etching occurs in a vacuum reaction chamber, in which an electrostatic chuck (ESC) 11 for carrying and adsorbing the wafer to be etched is disposed, and a consumable edge ring 12 is usually disposed on the periphery of the electrostatic chuck 11, and the edge ring 12 is used to improve the etching uniformity and consistency of the edge of the wafer 20.

[0003] Please continue to refer to Figure 1 , the height of the edge ring 12 has a crucial impact on the etching rate and plasma direction of the edge of the wafer 20. With the increase of process time and the number of times used, the edge ring 12 will gradually become thinner and tilted due to consumption by plasma, the etching rate of the wafer 20 will become faster and faster, and the plasma direction will tilt inward more and more, which will affect the performance and yield of the product. When the impact of the morphology of the edge ring 12 on the product exceeds the process window, equipment maintenance (PM) is required to replace the edge ring 12. The time interval between two equipment maintenance (period maintenance, PM) before and after the etching chamber is usually defined as the mean time between clean (MTBC) of the etching chamber. Obviously, on the plasma etching machine, the consumption of the edge ring 12 is the most important factor determining the processing time (MTBC) of the etching chamber.

[0004] In addition, in plasma etching equipment, due to the different process parameters such as process gas and RF power of different processes (also known as process / recipes), the consumption rate of the edge ring is different. When a new process is introduced for product production, if its impact on the edge ring cannot be estimated in advance, it is impossible to avoid the potential risks of the introduced new process. In particular, when the consumption rate of the edge ring of the new process becomes faster, MTBC should theoretically become smaller. If MTBC remains unchanged, the risk of yield deterioration caused by excessive consumption of the edge ring in the later stage will increase.

[0005] Therefore, it is urgent to develop a plasma etching chamber processing time prediction method, system and maintenance method, which can evaluate the processing time corresponding to the new process in advance before the new process is introduced through offline simulation, and then avoid the most likely risks based on the evaluation results. Summary of the invention

[0006] The purpose of the present invention is to provide a method, system and maintenance method for predicting the processing time of a plasma etching chamber, which can accurately evaluate the processing time of the etching chamber at a relatively low cost and in a relatively timely manner before a new process is introduced, thereby avoiding the risks brought about by the introduction of a new process.

[0007] To achieve the above object, the present invention provides a method for predicting processing time of a plasma etching chamber, comprising:

[0008] Experimental steps: before introducing a new process for product production, loading a test control wafer into a plasma etching chamber having an edge ring, and plasma etching the test control wafer using the new process, wherein the material of the test control wafer is the same as or similar to that of the edge ring, and during the plasma etching, the test control wafer and the edge ring are consumed synchronously;

[0009] Key data acquisition step: acquiring the consumption rate of at least one position of the test control piece, and acquiring the processing time of the plasma etching chamber under the existing process and the consumption rate of the corresponding position of the edge ring;

[0010] Estimation step: based on the consumption rate of at least one position of the test control piece, the processing time of the plasma etching chamber under the existing process and the consumption rate of the corresponding position of the edge ring, the processing time of the plasma etching chamber under the new process is estimated.

[0011] Optionally, in the experimental step, before loading the test control wafer into the plasma etching chamber having the edge ring, the plasma etching chamber is firstly subjected to waferless automatic cleaning.

[0012] Optionally, in the experimental steps, after the test control wafer is loaded into a plasma etching chamber having an edge ring and before the plasma etching is performed, a protective film is first deposited in the plasma etching chamber, and the protective film covers the inner surface of the plasma etching chamber, the surface of the edge ring, and the surface of the test control wafer; when the plasma etching is performed, the plasma first synchronously etches away the protective film on the surface of the edge ring and the surface of the test control wafer, and then synchronously etches away the edge ring and the test control wafer.

[0013] Optionally, after performing the plasma etching and before obtaining the consumption rate of at least one position of the test control wafer, the test control wafer is first removed and the plasma etching chamber is subjected to waferless automatic cleaning after a new process, and then the test control wafer is moved back to the plasma etching chamber; and / or, the test control wafer is retained in the plasma etching chamber and the plasma etching chamber is subjected to automatic cleaning after a new process.

[0014] Optionally, in the experimental step, before loading the test control piece into the plasma etching chamber, the test control piece is initially measured by a corresponding measuring tool to obtain the thickness of at least one position at the edge of the test control piece, and the at least one position includes a corresponding position on the front side of the edge of the test control piece and / or a corresponding position on the side wall; in the key data acquisition step, the test control piece is measured again by the measuring tool to obtain the thickness of at least one position at the edge of the test control piece after plasma etching, and based on the result of the initial measurement, the result of the re-measurement and the working time of the plasma etching chamber in the experimental step, the consumption rate of at least one position at the edge of the test control piece is obtained.

[0015] Optionally, in the key data acquisition step, the processing time of the plasma etching chamber and the consumption rate of the corresponding position of the edge ring under the existing process are obtained by collecting production data, edge ring consumption data and equipment maintenance data when the existing process produces multiple batches of products; or, the corresponding test control piece and the existing process are used to perform the experimental steps to obtain the processing time of the plasma etching chamber and the consumption rate of the corresponding position of the edge ring under the existing process.

[0016] Optionally, the consumption rate of at least one position of the test control piece under the new process obtained includes the consumption rate R1_new of the corresponding position on the front side of the edge of the test control piece under the new process and / or the consumption rate R2_new of the corresponding position on the side wall, the processing time of the plasma etching chamber under the existing process obtained is MTBC_bsl, and the consumption rate of the corresponding position of the edge ring under the existing process obtained includes the consumption rate R1_bsl of the corresponding position on the front side of the edge ring and / or the consumption rate R2_bsl of the corresponding position on the side wall; then the processing time of the plasma etching chamber under the new process obtained in the estimation step is MTBC_new=MTBC_bsl / / R_new,

[0017] Among them, R_new=R1_new / R1_bsl, or R_new=R2_new / R2_bsl, or R_new=max[(R1_new / R1_bsl),(R2_new / R2_bsl)].

[0018] Based on the same inventive concept, the present invention also provides a plasma etching chamber processing time prediction system, which includes:

[0019] At least one test control sheet, the material of the test control sheet is the same as or similar to that of the edge ring in the plasma etching chamber, and at least a part of the test control sheet is used to be loaded into the plasma etching chamber with the edge ring before introducing a new process for product production, and is plasma etched and consumed synchronously with the edge ring under the new process;

[0020] A key data acquisition component is used to obtain the consumption rate of at least one position of the test control piece that is plasma etched and consumed under the new process, and to obtain the processing time of the plasma etching chamber and the consumption rate of the corresponding position of the edge ring under the existing process, wherein the processing time of the plasma etching chamber under the new process is obtained based on the consumption rate of at least one position of the test control piece, the processing time of the plasma etching chamber under the existing process, and the consumption rate of the corresponding position of the edge ring.

[0021] Optionally, a portion of the test control wafers are used to be loaded into a plasma etching chamber having the edge ring before a new process is introduced for product production, and are plasma etched and consumed synchronously with the edge ring under the new process; another portion of the test control wafers are used to be loaded into a plasma etching chamber having the edge ring, and are plasma etched and consumed synchronously with the edge ring under the existing process;

[0022] Alternatively, the processing time of the plasma etching chamber under the new process is MTBC_new=MTBC_bsl / R_new,

[0023] Among them, R1_new is the front consumption rate at the edge of the test control piece under the new process, R2_new is the side wall consumption rate at the edge of the test control piece under the new process, MTBC_bsl is the processing time of the plasma etching chamber under the existing process, R1_bsl is the front consumption rate R1_bsl of the edge ring under the existing process, R2_bsl is the side wall consumption rate R2_bsl of the edge ring under the existing process; and R_new=R1_new / R1_bsl, or R_new=R2_new / R2_bsl, or R_new=max[(R1_new / R1_bsl),(R2_new / R2_bsl)].

[0024] Based on the same inventive concept, the present invention also provides a plasma etching chamber maintenance method, which comprises:

[0025] Plasma etching is performed on a wafer in a plasma etching chamber using an existing process, and equipment maintenance is performed on the plasma etching chamber based on a processing time of the plasma etching chamber under the existing process;

[0026] A new process is adopted to perform plasma etching on a wafer in a plasma etching chamber, and equipment maintenance of the plasma etching chamber is performed based on the processing time of the plasma etching chamber under the new process, wherein the processing time of the plasma etching chamber under the new process is obtained by a processing time prediction method of a plasma etching chamber as described in the present invention or a processing time prediction system of a plasma etching chamber as described in the present invention.

[0027] Compared with the prior art, the technical solution of the present invention has at least one of the following beneficial effects:

[0028] 1. The consumption rate of at least one position of the test control piece with the same or similar material as the edge ring under the new process is obtained through experiments as the consumption rate of the corresponding position of the edge ring under the new process. Therefore, the processing time of the plasma etching chamber under the new process can be estimated according to the processing time (MTBC) of the plasma etching chamber under the existing process and the consumption rate of the corresponding position of the edge ring and the consumption rate of the corresponding position of the edge ring under the new process. The processing time of the plasma etching chamber under the new process can be accurately evaluated at a low cost and in a relatively timely manner, thereby avoiding the risks brought by the introduction of the new process.

[0029] 2. Take full account of factors that affect the edge ring consumption, such as the formation of protective film in the plasma etching chamber, post-etching cleaning, and different processes, to design the experimental process so that the test control piece can 100% simulate the entire process of edge ring consumption, thereby improving the accuracy of the estimated processing time of the plasma etching chamber under the new process.

[0030] 3. The ratio of the side consumption rate or the front consumption rate of the new process and the existing process or the maximum value of the two is used to estimate the processing time of the plasma etching chamber under the new process. This can improve the error caused by the difference between the measurement position and the material of the test control piece used and the actual edge ring, and further improve the accuracy of the estimation of the processing time of the plasma etching chamber under the new process. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Those skilled in the art will appreciate that the accompanying drawings are provided for a better understanding of the present invention and do not constitute any limitation on the scope of the present invention.

[0032] Figure 1 It is a schematic diagram of the change process of the edge ring height and plasma direction in the plasma etching chamber under any process.

[0033] Figure 2It is a schematic diagram of the curve showing the change of edge ring height with the working time of the plasma etching chamber under the existing process and the new process.

[0034] Figure 3 It is a schematic flow chart of a method for predicting processing time of a plasma etching chamber according to a specific embodiment of the present invention.

[0035] Figure 4 It is a schematic diagram of changes in a plasma etching chamber in the experimental steps of a method for predicting processing time of a plasma etching chamber according to a specific embodiment of the present invention.

[0036] Figure 5 It is a schematic diagram of changes in a plasma etching chamber in a plasma etching method according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0037] In the following description, a large number of specific details are given in order to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features known in the art are not described. It should be understood that the present invention can be implemented in different forms and should not be interpreted as being limited to the embodiments proposed here. On the contrary, providing these embodiments will make the disclosure thorough and complete, and the scope of the present invention will be fully conveyed to those skilled in the art. The same reference numerals represent the same elements from beginning to end. It should be understood that when an element is referred to as "connected to", "coupled" other elements, it can be directly connected to other elements, or there can be intervening elements. On the contrary, when an element is referred to as "directly connected to" other elements, there is no intervening element. When used here, the singular forms of "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates another way. It should also be understood that the term "comprising" is used to identify the presence of possible features, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, steps, operations, elements, components and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items. The "Processing Time of Plasma Etching Chamber" (MTBC) herein is the time interval between two equipment maintenances due to edge ring consumption without unexpected failures.

[0038] In a plasma etching device, when a new process is introduced, if the consumption rate of the edge ring of the new process is faster than that of the existing process, such as Figure 2 As shown, the reasons for the potential risks are analyzed as follows:

[0039] First, the height of the new edge ring is A, and the MTBC corresponding to the existing process M1 is Y. During the entire MTBC period corresponding to the existing process M1 (i.e., within the Y duration), the height of the edge ring will be consumed from A to B, wherein B is the limit value of the preset safety height of the edge ring in the existing process, and MTBC=Y is the processing time of the etching chamber under the existing process, i.e., the interval time between opening the etching chamber twice and performing equipment maintenance due to the consumption of the edge ring when there is no unexpected failure.

[0040] Second, because the new process consumes the edge ring faster than the existing process, the new process consumes the edge ring height from A to B in a relatively short X time relative to Y, and then continues to consume the edge ring height from B to C in the time from X to Y.

[0041] That is to say, the actual MTBC=X after the introduction of the new process is shorter than the MTBC=Y of the original existing process. If the MTBC=Y of the existing process is still used to perform etching chamber maintenance after the introduction of the new process, it will pose a risk to the manufactured products and is likely to cause waste of production capacity.

[0042] To this end, the following two methods are generally used in the prior art to estimate the impact of the new process on the edge ring in advance:

[0043] Method 1: Use a new process and a large number of control wafers to conduct a simulation experiment (dummy season). After the simulation experiment, open the etching chamber to measure the size of the edge ring, and convert the actual edge ring consumption rate based on the process time (RF hour) of the etching chamber in the experiment. This method has the following disadvantages: (1) It takes a long time for the simulation experiment to obtain the results, the experimental data lacks timeliness, and wastes production capacity; (2) It requires high measurement accuracy, and the consumption rate of the edge ring varies with the distance between the edge ring and the plasma. If only a partial processing time simulation (partial MTBCseasoning) is performed, the results obtained will be different from the actual results; (3) It takes a long time for the simulation experiment, and the edge ring and other parts in the etching chamber are also consumed, which requires additional costs and wastes the edge ring and control wafers in the etching chamber.

[0044] Method 2: After a large number of product processes are completed, the consumption of the edge ring is evaluated by regular etching rate detection or inline yield of existing products and physical characteristics of the edge ring after use. This method has the following disadvantages: it has already affected some existing products and is irreversible. If the new process introduced consumes the edge ring faster and affects some existing products (such as Figure 2If the MTBC has a negative impact on the products produced from X to Y in the process, it is necessary to shorten the processing time MTBC, or add RF constraints to the existing process to make the MTBC of the existing process and the new process as equivalent as possible. However, it requires a long period of data accumulation on the production line to make the adjustment in place. If it is not timely, it is easy to cause waste of production capacity.

[0045] Therefore, there is a need for a plasma etching chamber processing time prediction method, system and plasma etching method, which can use offline simulation to accurately evaluate the processing time corresponding to a new process at a low cost and in a relatively timely manner before the new process is introduced, and then perform equipment maintenance in a timely manner according to the evaluation results, thereby avoiding the risks that may arise from the introduction of the new process and avoiding waste of production capacity.

[0046] The technical solution proposed by the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0047] Please refer to Figure 3 An embodiment of the present invention provides a method for predicting processing time of a plasma etching chamber, comprising:

[0048] S1 (experimental steps): before introducing a new process for product production, a test control wafer is loaded into a plasma etching chamber having an edge ring, and the test control wafer is plasma etched using the new process, and the material of the test control wafer is the same as or similar to that of the edge ring. During the plasma etching, the test control wafer and the edge ring are consumed synchronously;

[0049] S2 (key data acquisition step): obtaining the consumption rate of at least one position of the test control wafer, and obtaining the processing time of the plasma etching chamber under the existing process and the consumption rate of the corresponding position of the edge ring;

[0050] S3 (estimation step): based on the consumption rate of at least one position of the test control piece, the processing time of the plasma etching chamber under the existing process and the consumption rate of the corresponding position of the edge ring, the processing time of the plasma etching chamber under the new process is estimated.

[0051] Please refer to Figure 4 As an example, the process (flow) of S1 (experimental steps) includes:

[0052] S11, please refer to Figure 4In (A), before introducing a new process and before loading the test control wafer 21 into the plasma etching chamber, the plasma etching chamber is subjected to waferless automatic cleaning (WAC clean). In this step, corresponding cleaning gas (not shown) and purge gas (not shown) can be introduced into the plasma etching chamber successively or simultaneously. The cleaning gas is, for example, oxygen, sulfur hexafluoride, nitrogen trifluoride, carbon tetrafluoride or chlorine, which can be ionized into plasma by the plasma etching chamber to clean the residual products left by the previous process in the plasma etching chamber. The purge gas is, for example, an inert gas such as argon or helium, which can purge the inner surface of the plasma etching chamber and the exposed surfaces of components such as the electrostatic adsorption chuck 11 inside the plasma etching chamber to discharge the cleaning gas and the residual products cleaned in the plasma etching chamber, thereby providing a clean etching environment for the execution of the new process.

[0053] S12, please refer to Figure 4 In (A), after completing waferless automatic cleaning (WAC clean), the corresponding test control piece 21 is loaded onto the electrostatic adsorption chuck 11 in the plasma etching chamber, and the outer periphery of the test control piece 21 is surrounded by an edge ring 12. The edge ring 12 can be brand new or not brand new, wherein a brand new one is preferred, thereby preventing the height of the edge ring 12 from dropping below the safety limit during the experiment and affecting the accuracy of the estimated results. In addition, the material of the test control piece 21 needs to be the same or similar to that of the edge ring 12, thereby ensuring that each position on the edge of the test control piece 21 can subsequently 100% simulate the consumption rate of the corresponding position of the edge ring 12. For example, when the material of the edge ring 12 is glass, the material of the test control piece 21 can be glass, or it can be silicon dioxide, or the test control piece 21 is a composite structure with silicon dioxide deposited on the surface of a silicon wafer.

[0054] S13, please refer to Figure 4 In (B), a corresponding deposition gas is introduced into the plasma etching chamber, and the deposition gas can form a protective film 13 on the inner surface of the plasma etching chamber, the exposed surface of the edge ring 12 and other components inside the plasma etching chamber, and the surface of the test control piece 21. Figure 5 In (A) and (B), the process for forming the protective film 13 can be the same as the process for forming the protective film before plasma etching when the product is produced under the existing process. Among them, by adjusting the process parameters such as the flow rate of the deposition gas, the gas pressure, the radio frequency power, the electrode current, the deposition time, etc., the protective film 13 can be deposited on the surface of the test control piece 21, the inner surface of the plasma etching chamber, and the exposed surfaces of all parts except the electrostatic chuck 11, and the uniformity and thickness of the protective film 13 can be controlled, thereby eliminating the influence of the differences in the surface properties of various structures inside the plasma etching chamber on the subsequent new process technology, and improving the accuracy of estimating the processing time of the plasma etching chamber under the new process.

[0055] S14, please refer to Figure 4 In (C), the new process is used to perform plasma etching on the test control wafer 21. In this process, the process gas and its flow rate, gas pressure, RF power, electrode current, deposition time and other process parameters in the plasma etching chamber are all defined by the process recipe of the new process, and the plasma direction in the plasma etching is vertically downward. In this embodiment, the protective film 13 formed in step S13 is the same in thickness and material as the protective film formed in the existing process, and in step S14, the thickness of the protective film 13 is not enough to support the completion of plasma etching under the new process, so that the plasma etching consumes the edge ring 12 and the test control piece 13. In the vertically downward plasma etching process, the consumption rate of the protective film 13 on the upper surface of the edge ring 12 and other components and the entire upper surface of the test control piece 13 is relatively large, and the consumption rate of the protective film on the inner side wall and the top surface of the plasma etching chamber is relatively small. The material of the edge ring 12 and the test control piece 21 is the same or similar, so the protective film 13 on the upper surface of the edge ring 12 and the upper surface of the test control piece 21 is quickly removed by synchronous etching, and then the edge ring 12 and the test control piece 21 continue to be synchronously etched and consumed under the new process. In this process, the consumption rate of the edge of the test control piece 21 can 100% simulate the consumption rate of the edge ring 12. It should be understood that in other embodiments of the present invention, when the thickness of the protective film 13 is thick enough, the plasma etching under the new process is not sufficient to completely consume this layer of protective film 13. After the plasma etching is completed, the surface of the edge ring 12 and the test control piece 21 are still covered and protected by the protective film 13, and there will be no consumption. At this time, the consumption rate of the edge of the test control piece 21 and the consumption rate of the edge ring 12 are both 0. The consumption rate of the edge of the test control piece 21 can also be regarded as being able to 100% simulate the consumption rate of the edge ring 12.

[0056] S15, please refer to Figure 4In (D), after the new process is completed, the plasma etching chamber can be automatically cleaned after etching without removing the test control piece 21 from the plasma etching chamber. In this case, while the edge ring 12 is consumed in the automatic cleaning process after etching, the test control piece 21 is also consumed synchronously, so that the edge of the test control piece 21 can 100% simulate the entire consumption process of the edge ring 12 after the new process is introduced. At this time, the consumption thickness at the corresponding position of the edge of the test control piece 21 is divided by the sum of the process time (process recipe RF on) of the new process and the automatic cleaning time after etching (that is, the thickness is divided by the time), and the consumption rate of the corresponding position of the edge of the test control piece 21 after the new process is introduced can be obtained, which is also the consumption rate of the corresponding position of the edge ring 12 after the new process is introduced. In this way, factors that affect the edge ring consumption, such as the formation of the protective film 13 in the plasma etching chamber, automatic cleaning after etching, and different processes, can be fully considered, so that the edge of the test control piece can 100% simulate the entire process of edge ring consumption, thereby improving the accuracy of the estimated processing time of the plasma etching chamber under the new process.

[0057] In other embodiments, if the process parameters such as the gas of the post-etching automatic cleaning process are selected reasonably, and the consumption of the edge ring 12 by the automatic cleaning process after etching of different processes can be ignored, then in step S15, the test control piece 21 can be first moved out of the plasma etching chamber, and then the plasma etching chamber is subjected to waferless automatic cleaning after etching, and then the test control piece 21 can be transferred back to the plasma etching chamber as needed, or the test control piece 21 can be directly transferred to the corresponding measurement tool to measure key data. In this case, the edge of the test control piece 21 can also 100% simulate the entire consumption process of the edge ring 12 after the new process is introduced. At this time, the consumption thickness at the corresponding position of the edge of the test control piece 21 is divided by the process time (process recipe RF on) of the new process, and the consumption rate of the edge of the test control piece 21 after the new process is introduced can be obtained, which is also the consumption rate of the edge ring 12 after the new process is introduced.

[0058] It should be understood that the process parameters such as gas type, gas flow rate, cleaning time, etc. used in the automatic cleaning after etching in step S15 can be the same as the waferless automatic cleaning process in step S11, or can be reasonably selected based on the type and degree of residual products that may be generated by the new process in step S14.

[0059] In addition, the consumption rates of the front side and the side wall at the edge of the test control piece 21 may vary due to different plasma etching directions. Therefore, in step S2, one or both of the consumption rate of the front side and the consumption rate of the side wall at the edge of the test control piece 21 can be selected to obtain, thereby using the consumption rate of the test control piece obtained in step S2 for step S3. Among them, in order to obtain the consumption rate of the front side and the consumption rate of the side wall at the edge of the test control piece 21, it is necessary to obtain the consumption thickness of the front side and the side wall at the edge of the test control piece 21. Therefore, it is necessary to first know the initial thickness D0 of at least one position on the front side of the edge of the test control piece 21 (referred to as the initial front thickness at the edge of the test control piece 21) and the initial width W0 of at least one position on the side wall of the test control piece 21 (referred to as the initial side wall thickness at the edge of the test control piece 21) before the new process is introduced. After the new process is completed, the remaining thickness D1 or D2 of the corresponding position of the test control piece 21 (i.e., the thickness of the corresponding position on the front side of the edge of the test control piece 21 after the new process, referred to as the current front thickness at the edge of the test control piece 21) and W1 or W2 (i.e., the width of the corresponding position on the side wall of the edge of the test control piece 21 after the new process, referred to as the current side wall thickness at the edge of the test control piece 21) are obtained. Therefore, if the plasma etching chamber does not have a film thickness monitoring and measuring tool, before step S12 of step S1, the test control piece 21 is first transferred to the corresponding measuring tool, and the initial front thickness D0 and the initial side wall thickness W0 of the edge of the test control piece 21 are initially measured; in step S2, the test control piece 21 after the new process is completed and moved out of the plasma etching chamber is transferred to the measuring tool used in step S1, and the current front thickness (D1 or D2) and the current side wall thickness (W1 or W2) of the edge of the test control piece 21 are measured again.

[0060] Therefore, by using the difference between the initial measurement result obtained in step S1 and the re-measurement result obtained in step S2, the consumed thickness (△D=D0-D1 or D0-D2) of the corresponding position on the edge front of the test control piece 21 and / or the consumed thickness (△W=W0-W1 or W0-W2) of the corresponding position on the side wall can be calculated.

[0061] If the plasma etching chamber itself is provided with a measuring tool for monitoring the film thickness, then after S12 of step S1 and before executing step S13, the measuring tool provided with the plasma etching chamber itself is used to measure the initial front thickness D0 and the initial side wall thickness W0 at the edge of the test control piece 2. In step S2, after the new process is completed or after the automatic cleaning after etching is completed, the measuring tool provided with the plasma etching chamber itself is used to measure the current front thickness (D1 or D2) and the current side wall thickness W1 or W2) at the edge of the test control piece 2 again, thereby calculating the difference between the initial measurement result obtained in step S1 and the re-measurement result obtained in step S2, and obtaining the consumed thickness (△D=D0-D1 or D0-D2) of the edge of the test control piece 21 and the consumed thickness (△W=W0-W1 or W0-W2) of the side wall.

[0062] It is worth noting that D0 can be the initial thickness of any position on the front side of the edge of the test control sheet 21 (can be a specified position on the front side of the edge), or the average value or maximum value of the initial thickness of multiple positions on the front side of the edge of the test control sheet 21 (can be multiple specified positions on the front side of the edge); W0 can be the initial thickness of any position on the side wall of the edge of the test control sheet 21 (can be a specified position on the side wall of the edge), or the average value or maximum value of the initial thickness of multiple positions on the side wall of the edge of the test control sheet 21 (can be multiple specified positions on the side wall of the edge). Correspondingly, D1 or D2 can be the current remaining thickness of the position corresponding to D0 measurement on the front side of the edge of the test control sheet 21 after undergoing a new process, or the average value or maximum value of the current remaining thickness of multiple positions on the front side of the edge corresponding to D0 measurement; W1 or W2 can be the current remaining thickness of the position corresponding to W0 measurement on the side wall of the edge of the test control sheet 21 after undergoing a new process, or the average value or maximum value of the current remaining thickness of multiple positions on the side wall of the edge of the test control sheet 21 corresponding to W0 measurement.

[0063] Optionally, after completing the re-measurement, the edge of the test control piece 21 can be further sliced ​​and scanned by a scanning electron microscope (SEM) to re-verify the accuracy of the consumed thickness on the front edge of the test control piece 21 and the consumed thickness on the side wall to ensure the accuracy of the estimated results.

[0064] In step S2, after obtaining the consumed thickness of the edge front and the consumed thickness of the side wall of the test control piece 21 after undergoing the new process, the front edge consumption rate R1_new=△D / t can be obtained by dividing the front edge consumption thickness △D by the process time t after the new process is introduced, and the side wall consumption rate R2_new=△W / t can be obtained by dividing the side wall consumption thickness △W by the process time t after the new process is introduced, △D=D0-D1 or D0-D2, △W=W0-W1 or W0-W2, t=t1 or t1+t2, wherein t1 is the process time (process recipe RF on) of the new process, and t2 is the process time of the new process for automatic cleaning after etching.

[0065] In step S2, it is also necessary to obtain the processing time MTBC_bsl of the plasma etching chamber under the existing process, the consumption rate R1_bsl of the corresponding position of the edge ring front surface, and the consumption rate R2_bsl of the corresponding position of the side wall. R1_bsl can be the maximum value or average value of the consumption rates of multiple positions on the front surface of the edge ring or the consumption rate of a specified position, and R1_bsl can be the maximum value or average value of the consumption rates of multiple positions on the side wall of the edge ring or the consumption rate of a specified position.

[0066] One of the methods is to collect a large amount of historical relevant data on the production line (such as regular etching rate detection, product yield, edge ring height measurement data, equipment maintenance cycle, etc.) and analyze these historical relevant data. For example, the production data, edge ring consumption data and equipment maintenance data and other relevant data are collected when multiple batches of products are produced through the existing process on the production line to obtain the processing time MTBC_bsl of the plasma etching chamber under the existing process (which is the time interval between two equipment maintenances performed due to the consumption of the edge ring 12 when there is no unexpected failure, which can be an average value or a minimum value) and the consumption rate of the corresponding position of the edge ring (i.e., R1_bsl and / or R2_bsl).

[0067] Another method is to use another test control piece and an existing process to perform step S1 (i.e., the experimental step), wherein the process used in step S14 of step S1 is the existing process, thereby obtaining the consumption rate R1_new of the corresponding position on the front side of the edge ring and the consumption rate R2_new of the corresponding position on the side wall under the new process. Similarly, the consumption rate of at least one position at the edge of the other test control piece (including the corresponding position on the front side of the edge of the other test control piece and / or the corresponding position on the side wall, which are the same as the measurement position of D0 mentioned above) is obtained (the calculation method of the rate is also the same as the method under the new process mentioned above), and then correspondingly obtain the front consumption rate R1_bsl and / or side wall consumption rate R2_bsl of the edge ring under the existing process (i.e., using the experimental steps provided by the present invention, no matter the consumption rate collected under the new process or the existing process, the consumption rate of the side (or top) of the edge ring is equivalent to the consumption rate of the side (or top) of the edge ring through the consumption rate of the side (or top) of the test control piece). In addition, by collecting historical relevant data on the production line, the processing time MTBC_bsl of the plasma etching chamber under the existing process is obtained.

[0068] In step S3, based on the key data obtained in step S2, the processing time MTBC_new of the plasma etching chamber under the new process is calculated, which is exemplarily shown in the following formula:

[0069] MTBC_new=MTBC_bsl / R_new.

[0070] Wherein, R_new=R1_new / R1_bsl, or R_new=R2_new / R2_bsl, or R_new=max[(R1_new / R1_bsl),(R2_new / R2_bsl)], MTBC_bsl is the processing time of the plasma etching chamber under the existing process, R1_bsl is the consumption rate of the corresponding position of the front side of the edge ring under the existing process, and R1_bsl can be the maximum consumption rate on the front side of the edge ring under the existing process, the consumption rate of any specified position or the average consumption rate of multiple specified positions, R2_bsl is the consumption rate of the corresponding position of the side wall of the edge ring under the existing process, and R2_bsl is the consumption rate of the corresponding position of the side wall of the edge ring under the existing process. sl can be the maximum consumption rate on the side wall at the edge under the existing process, the consumption rate at any specified position, or the average consumption rate at multiple specified positions, R1_new is the consumption rate at the corresponding position on the front side of the edge of the test control piece under the new process, and R1_new can be the maximum consumption rate on the front side of the edge under the new process, the consumption rate at any specified position, or the average consumption rate at multiple specified positions, R2_new is the consumption rate at the corresponding position on the side wall at the edge of the test control piece under the new process, and R2_new can be the maximum consumption rate on the side wall at the edge under the new process, the consumption rate at any specified position, or the average consumption rate at multiple specified positions. max[] is a maximum value function, which can take a larger ratio between the ratios R1_new / R1_bsl and R2_new / R2_bsl.

[0071] In this step, one of the maximum values ​​of R1_new / R1_bsl, R2_new / R2_bsl and R1_new / R1_bsl\R2_new / R2_bs is used, and further combined with MTBC_bsl to estimate the processing time MTBC_new of the plasma etching chamber under the new process. This can improve the error caused by the difference between the measurement position and the material of the test control piece 21 used and the actual edge ring 12, and further improve the accuracy of the estimation of the processing time of the plasma etching chamber under the new process.

[0072] From the above description, it can be seen that the processing time prediction method of the plasma etching chamber of the present embodiment can use the test control piece to perform experimental simulation to quickly obtain the consumption rate of the front and / or side wall of the edge ring under the new process, and then combine the consumption rate under the new process and the consumption rate under the existing process The ratio (i.e., R1_new / R1_bsl or R2_new / R2_bsl or max[(R1_new / R1_bsl), (R2_new / R2_bsl)]) and the processing time MTBC_bsl under the existing process can be used to estimate the processing time MTBC_new under the new process. This can reduce the samples required for the experiment, shorten the estimation time, and avoid the problems of experimental costs and waste of production capacity caused by a large number of long-term experiments in the prior art to obtain the MTBC_new of the new process. It can also avoid the risk problems caused by directly introducing the new process into the production line and evaluating it while producing. Finally, the processing time corresponding to the new process is evaluated at a relatively low cost and in a relatively timely and accurate manner, and then the equipment maintenance can be carried out in time according to the evaluation results, avoiding the risks that may be caused by the introduction of the new process.

[0073] Preferably, the processing time MTBC_new under the new process is estimated using max[(R1_new / R1_bsl), (R2_new / R2_bsl)] and the processing time MTBC_bsl under the existing process, that is:

[0074] MTBC_new=MTBC_bsl / max[(R1_new / R1_bsl), (R2_new / R2_bsl)].

[0075] In this way, the different consumption of the edge ring on the front and side walls under different processes are taken into consideration at the same time (some processes consume the edge ring front quickly but consume the edge ring side walls slowly, while some processes consume the edge ring front slowly but consume the edge ring side walls quickly), thereby improving the accuracy of the estimated results of the processing time MTBC_new under the new process.

[0076] Based on the same invention concept, please combine Figure 4 An embodiment of the present invention further provides a plasma etching chamber processing time prediction system, which can be used to implement the plasma etching chamber processing time prediction method of the present invention. The processing time prediction system includes:

[0077] At least one test control piece 21, the material of the test control piece 21 is the same as or similar to the edge ring 12 in the plasma etching chamber, and at least a part of the test control piece 21 is used to be loaded into the plasma etching chamber with the edge ring 12 before introducing a new process for product production, and is plasma etched and consumed synchronously with the edge ring 12 under the new process;

[0078] A key data acquisition component (not shown) is used to obtain the consumption rate of at least one position of the test control piece that is plasma etched and consumed under the new process, and to obtain the processing time of the plasma etching chamber and the consumption rate of the corresponding position of the edge ring under the existing process, wherein the processing time of the plasma etching chamber under the new process is obtained based on the consumption rate of at least one position of the test control piece, the processing time of the plasma etching chamber under the existing process, and the consumption rate of the corresponding position of the edge ring.

[0079] Optionally, the key data acquisition component includes a corresponding measuring tool (not shown) and a calculation tool (not shown). The measuring tool can be integrated in the plasma etching chamber or set outside the plasma etching chamber. Before the corresponding process (new process or existing process) is introduced, the initial thickness D0 and W0 of the corresponding position at the edge of the test control piece 21 are obtained, and after the corresponding process (new process or existing process) is completed, the remaining thickness D1 or D2 and W1 or W2 of the corresponding position of the test control piece 21 are obtained. The calculation tool can use the measurement results of the measuring tool and the corresponding process time to calculate the consumption rate of the corresponding position on the front of the edge ring 12 and / or the consumption rate of the corresponding position on the side wall under the corresponding process, and can further combine the consumption rate of the corresponding position on the front of the edge ring 12 and / or the consumption rate of the corresponding position on the side wall under the new process and the existing process and the processing time MTBC_bsl of the plasma etching chamber under the existing process to calculate the processing time MTBC_new of the plasma etching chamber under the new process:

[0080] MTBC_new=MTBC_bsl / R_new.

[0081] Among them, R_new=R1_new / R1_bsl, or R_new=R2_new / R2_bsl, or R_new=max[(R1_new / R1_bsl),(R2_new / R2_bsl)], R1_new is the consumption rate of the corresponding position on the front side of the edge of the test control piece under the new process, and R1_new can be the maximum consumption rate on the front side of the edge of the test control piece under the new process, the consumption rate of any specified position, or the average consumption rate of multiple specified positions; R2_new is the consumption rate of the corresponding position on the side wall at the edge of the test control piece under the new process, and R2_new can be the maximum consumption rate on the side wall at the edge of the test control piece under the new process, the consumption rate of any specified position, or the average consumption rate of multiple specified positions. MTBC_bsl is the processing time of the plasma etching chamber under the existing process, R1_bsl is the consumption rate of the front side of the edge ring under the existing process, and R1_bsl can be the maximum consumption rate on the front side of the edge under the existing process, the consumption rate at any specified position, or the average consumption rate at multiple specified positions, R2_bsl is the side wall consumption rate of the edge ring under the existing process, and R2_bsl can be the maximum consumption rate on the side wall of the edge under the existing process, the consumption rate at any specified position, or the average consumption rate at multiple specified positions. max[] is a maximum value function, which can take a larger ratio between the ratios R1_new / R1_bsl and R2_new / R2_bsl.

[0082] It should be understood that in other embodiments of the present invention, the key data acquisition component can also omit the calculation tool, wherein the designed calculation can be implemented manually.

[0083] Optionally, the key data acquisition component may also include a slicing device (not shown) and a scanning electron microscope (SEM, not shown). The slicing device is used to slice the edge of the test control piece 21 after measuring the consumed thickness on the front side of the edge and the consumed thickness on the side wall of the corresponding test control piece 21 after undergoing a new process. The scanning electron microscope is used to scan the edge of the test control piece 21 after slicing to secondary verify the accuracy of the measured consumed thickness on the front side of the edge of the test control piece 21 and the consumed thickness on the side wall to ensure the accuracy of the estimated results.

[0084] Optionally, a portion of the test control wafers 21 are used to be loaded into a plasma etching chamber having an edge ring before a new process is introduced for product production, and are plasma etched and consumed synchronously with the edge ring under the new process. Another portion of the test control wafers 21 are used to be loaded into the plasma etching chamber having an edge ring, and are plasma etched and consumed synchronously with the edge ring under the existing process.

[0085] In addition, it should be noted that in the above embodiments, when the consumption rate of the corresponding position on the front of the edge ring under the new process and the existing process is obtained by experimenting with the test control piece, at least one position on the front of the edge of the test control piece is selected to measure the thickness and calculate the consumption rate. This is because the edge of the test control piece is relatively close to the edge, and the plasma etching condition at the edge of the test control piece is closer to the plasma etching condition of the edge ring, so the accuracy of the final estimated result can be guaranteed. However, the technical solution of the present invention is not limited to this. In other embodiments of the present invention, when the plasma etching conditions of the edge area and the central area of ​​the test control piece are basically the same, only at least one position on the front of the central area of ​​the test control piece can be selected to measure the thickness and calculate the consumption rate, and the calculation result can be applied to the processing time of the plasma etching chamber under the new process, or at least one position on the front of the central area of ​​the test control piece and at least one position on the front of the edge of the test control piece are selected to measure the thickness and calculate the average consumption rate, and the average calculation result can be applied to the processing time of the plasma etching chamber under the new process.

[0086] Please refer to Figure 5 Based on the same inventive concept, an embodiment of the present invention further provides a plasma etching chamber maintenance method, which is used to timely maintain the plasma etching chamber during the product production process on the production line, and includes:

[0087] First, plasma etching is performed on a wafer in a plasma etching chamber using an existing process, and equipment maintenance is performed on the plasma etching chamber based on a processing time of the plasma etching chamber under the existing process;

[0088] Next, the wafer in the plasma etching chamber is plasma etched using the new process, and equipment maintenance is performed on the plasma etching chamber based on the processing time of the plasma etching chamber under the new process, wherein the processing time of the plasma etching chamber under the new process is obtained by the processing time prediction method of the plasma etching chamber as described in the present invention or the processing time prediction system of the plasma etching chamber as described in the present invention.

[0089] The above-mentioned plasma etching of the wafer in the plasma etching chamber using the existing process and the plasma etching of the wafer in the plasma etching chamber using the new process include the following processes:

[0090] First, please refer to Figure 5 (A) in which the plasma etching chamber is subjected to waferless automatic cleaning (WAC clean). The process may refer to the contents of step S11 above and will not be described in detail here;

[0091] Next, please refer to Figure 5In (A), a protective film (pre-coat) 13 is deposited in the plasma etching chamber. The protective film 13 covers the inner surface of the plasma etching chamber and the surfaces of the edge ring 12 and the electrostatic adsorption chuck 11. The process can be referred to the content of step S13 above and will not be described in detail here;

[0092] Then, please refer to Figure 5 In (B) and (C), the wafer 20 is loaded into the plasma etching chamber and is carried and adsorbed by the electrostatic adsorption chuck 11 (wafer place in), and the corresponding process (run process) is performed;

[0093] Afterwards, please refer to Figure 5 (C) and (D) in the process are completed after the process, the wafer 20 is moved out of the plasma etching chamber, and the plasma etching chamber is again subjected to waferless automatic cleaning (WAC clean). This step can be referred to as the content of step S11 or S15 above, and will not be described in detail here.

[0094] The plasma etching method of this embodiment is relatively timely and accurate, because the processing time of the plasma etching chamber under the new process is obtained by the plasma etching chamber processing time prediction method or the plasma etching chamber processing time prediction system as described in the present invention, and can avoid the problem of premature equipment maintenance or late equipment maintenance due to inaccurate processing time assessment after the introduction of the new process.

[0095] The above description is only a description of the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for predicting processing time of a plasma etching chamber, characterized in that: include: Experimental steps: before introducing a new process for product production, loading a test control wafer into a plasma etching chamber having an edge ring, and plasma etching the test control wafer using the new process, wherein the material of the test control wafer is the same as or similar to that of the edge ring, and during the plasma etching, the test control wafer and the edge ring are consumed synchronously; Key data acquisition step: acquiring the consumption rate of at least one position of the test control piece, and acquiring the processing time of the plasma etching chamber under the existing process and the consumption rate of the corresponding position of the edge ring; Estimation step: based on the consumption rate of at least one position of the test control piece, the processing time of the plasma etching chamber under the existing process and the consumption rate of the corresponding position of the edge ring, the processing time of the plasma etching chamber under the new process is estimated.

2. The processing time prediction method according to claim 1, characterized in that: In the experimental steps, before loading the test control wafer into the plasma etching chamber with the edge ring, the plasma etching chamber is firstly subjected to waferless automatic cleaning before a new process.

3. The processing time prediction method according to claim 1, characterized in that: In the experimental steps, after the test control wafer is loaded into a plasma etching chamber having an edge ring and before the plasma etching is performed, a protective film is first deposited in the plasma etching chamber, and the protective film covers the inner surface of the plasma etching chamber, the surface of the edge ring, and the surface of the test control wafer; when the plasma etching is performed, the plasma first synchronously etches away the protective film on the surface of the edge ring and the surface of the test control wafer, and then synchronously etches away the edge ring and the test control wafer.

4. The processing time prediction method according to claim 3, characterized in that: After performing the plasma etching and before obtaining the consumption rate of at least one position of the test control wafer, first remove the test control wafer and perform waferless automatic cleaning after a new process on the plasma etching chamber, and then move the test control wafer back to the plasma etching chamber; and / or, keep the test control wafer in the plasma etching chamber and perform automatic cleaning after a new process on the plasma etching chamber.

5. The processing time prediction method according to any one of claims 1 to 4, characterized in that: In the experimental step, before loading the test control piece into the plasma etching chamber, the test control piece is initially measured by a corresponding measuring tool to obtain the thickness of at least one position at the edge of the test control piece, and the at least one position includes a corresponding position on the front side of the edge of the test control piece and / or a corresponding position on the side wall; in the key data acquisition step, the test control piece is measured again by the measuring tool to obtain the thickness of at least one position at the edge of the test control piece after plasma etching, and based on the result of the initial measurement, the result of the re-measurement and the working time of the plasma etching chamber in the experimental step, the consumption rate of at least one position at the edge of the test control piece is obtained.

6. The processing time prediction method according to any one of claims 1 to 4, characterized in that: In the key data acquisition step, the processing time of the plasma etching chamber and the consumption rate of the corresponding position of the edge ring under the existing process are obtained by collecting the production data, edge ring consumption data and equipment maintenance data when the existing process produces multiple batches of products; or, the corresponding test control piece and the existing process are used to perform the experimental steps to obtain the processing time of the plasma etching chamber and the consumption rate of the corresponding position of the edge ring under the existing process.

7. The processing time prediction method according to claim 1, characterized in that: The consumption rate of at least one position of the test control piece under the new process obtained includes the consumption rate R1_new of the corresponding position on the front side of the edge of the test control piece under the new process and / or the consumption rate R2_new of the corresponding position on the side wall. The processing time of the plasma etching chamber under the existing process obtained is MTBC_bsl. The consumption rate of the corresponding position of the edge ring under the existing process obtained includes the consumption rate R1_bsl of the corresponding position on the front side of the edge ring and / or the consumption rate R2_bsl of the corresponding position on the side wall. Then the processing time of the plasma etching chamber under the new process obtained in the estimation step is MTBC_new=MTBC_bsl / R_new, wherein R_new=R1_new / R1_bsl, or R_new=R2_new / R2_bsl, or R_new=max[(R1_new / R1_bsl),(R2_new / R2_bsl)].

8. A plasma etching chamber processing time prediction system, characterized in that: include: At least one test control sheet, the material of the test control sheet is the same as or similar to that of the edge ring in the plasma etching chamber, and at least a part of the test control sheet is used to be loaded into the plasma etching chamber with the edge ring before introducing a new process for product production, and is plasma etched and consumed synchronously with the edge ring under the new process; A key data acquisition component is used to obtain the consumption rate of at least one position of the test control piece that is plasma etched and consumed under the new process, and to obtain the processing time of the plasma etching chamber and the consumption rate of the corresponding position of the edge ring under the existing process, wherein the processing time of the plasma etching chamber under the new process is obtained based on the consumption rate of at least one position of the test control piece, the processing time of the plasma etching chamber under the existing process, and the consumption rate of the corresponding position of the edge ring.

9. The processing time prediction system according to claim 8, characterized in that: A portion of the test control wafers is used to be loaded into a plasma etching chamber having the edge ring before a new process is introduced for product production, and is plasma etched and consumed synchronously with the edge ring under the new process; another portion of the test control wafers is used to be loaded into a plasma etching chamber having the edge ring, and is plasma etched and consumed synchronously with the edge ring under the existing process; Alternatively, the processing time of the plasma etching chamber under the new process MTBC_new=MTBC_bsl / R_new, Wherein, R1_new is the consumption rate of the corresponding position on the front side of the edge of the test control piece under the new process, R2_new is the consumption rate of the corresponding position on the side wall of the edge of the test control piece under the new process, MTBC_bsl is the processing time of the plasma etching chamber under the existing process, R1_bsl is the consumption rate R1_bsl of the corresponding position on the front side of the edge ring under the existing process, and R2_bsl is the consumption rate R2_bsl of the corresponding position on the side wall of the edge ring under the existing process; And R_new=R1_new / R1_bsl, or R_new=R2_new / R2_bsl, or R_new=max[(R1_new / R1_bsl),(R2_new / R2_bsl)].

10. A method for maintaining a plasma etching chamber, characterized in that: include: Plasma etching is performed on a wafer in a plasma etching chamber using an existing process, and equipment maintenance is performed on the plasma etching chamber based on a processing time of the plasma etching chamber under the existing process; A new process is adopted to perform plasma etching on a wafer in a plasma etching chamber, and equipment maintenance is performed on the plasma etching chamber based on the processing time of the plasma etching chamber under the new process, wherein the processing time of the plasma etching chamber under the new process is obtained by the processing time prediction method of the plasma etching chamber as described in any one of claims 1 to 7 or the processing time prediction system of the plasma etching chamber as described in claim 8 or 9.

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