Etching process control method and device
The etching process control method and device address gas flow inconsistencies by monitoring actual flow and adjusting processes based on preset ranges, improving wafer yield through accurate gas flow management and real-time data optimization.
Patent Information
- Application Number
- CN202110507228.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-05-10
- Publication Date
- 2024-12-13
- Estimated Expiration
- 2041-05-10
AI Technical Summary
In semiconductor etching processes, the gas flow rate control using a final valve is inconsistent due to inherent errors and corrosion by plasma gas, affecting wafer yield, especially as etching sizes reach the nanometer level.
An etching process control method and device that uses a detection node to monitor actual gas flow, determines flow deviation, and adjusts the etching process based on preset value ranges, incorporating big data to optimize gas flow and improve yield.
Accurately controls gas flow to prevent excessive or insufficient etching, enhancing wafer yield by minimizing deviations caused by valve errors and corrosion, and providing real-time data support for process optimization.
Smart Images
Figure CN115332033B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of etching technology, and in particular to an etching process control method and device. Background Art
[0002] In the semiconductor process, during the etching process using plasma gas, the gas flow rate will affect the yield of the wafer.
[0003] In this regard, in the prior art, a final valve is provided at the outlet of the gas mixing chamber to control the gas flow rate.
[0004] However, due to inherent errors and corrosion of the valve by plasma gas, the gas flow rate set by the final valve is not completely consistent with the gas flow rate entering the etching chamber, which has an adverse effect on the yield of the wafer. Summary of the invention
[0005] In view of the above analysis, the present invention aims to provide an etching process control method and device to improve the yield of wafers.
[0006] The purpose of the present invention is mainly achieved through the following technical solutions:
[0007] In a first aspect, an embodiment of the present invention provides an etching process control method, comprising:
[0008] Receive an etching start instruction;
[0009] According to the etching start instruction, first gas flow data is obtained from the final valve, and second gas flow data is obtained from a preset detection node;
[0010] Determining a flow deviation between a theoretical air flow and an actual air flow according to the first air flow data and the second air flow data;
[0011] The current etching process is controlled according to the relationship between the flow deviation and the preset value range.
[0012] Further, when the flow rate deviation is within the preset value range, the current etching process is maintained;
[0013] When the flow rate deviation is greater than the maximum endpoint value of the preset value range, terminating the current etching process;
[0014] When the flow deviation is less than the minimum endpoint value of the preset value range, the gas flow rate of the current etching process is increased.
[0015] Further, the yield of each etched wafer is determined;
[0016] The flow deviation and the yield are stored correspondingly.
[0017] Furthermore, the preset value range is determined according to the corresponding relationship between the flow deviation and the yield.
[0018] Further, the preset value range includes a first value range;
[0019] The first value range is determined according to the flow deviation and yield corresponding to the etching equipment.
[0020] Further, the value range includes a second value range;
[0021] The second value range is applicable to determining the second value range according to the flow deviation and yield corresponding to the etching process.
[0022] Furthermore, the preset value range includes: a first value range and a second value range;
[0023] Determining the first value range according to the flow deviation and yield rate corresponding to the etching equipment;
[0024] Determining the second value range according to the flow deviation and yield corresponding to the etching process;
[0025] Determine the intersection of the first value range and the second value range as the preset value range.
[0026] In a second aspect, an embodiment of the present invention provides an etching process control device, including: a gas flow meter and a controller;
[0027] The gas flow meter is arranged at a preset detection node, and the detection node is arranged on a side of the etching gas delivery pipeline close to the gas inlet of the etching chamber;
[0028] The controller is respectively connected to the final valve and the gas flow meter, and is used to obtain the first gas flow data from the final valve and the second gas flow data from the gas flow meter; based on the first gas flow data and the second gas flow data, the flow deviation between the theoretical gas flow and the actual gas flow is determined; based on the relationship between the flow deviation and the preset value range, the current etching process is controlled.
[0029] Furthermore, the device further comprises: a signal converter;
[0030] One end of the signal converter is connected to the gas flow meter, and the other end is connected to the controller;
[0031] When the data format used by the gas flow meter is different from the data format used by the controller, the signal converter is used to convert the second gas flow data from the data format used by the gas flow meter to the data format used by the controller.
[0032] Furthermore, the device also includes: a database;
[0033] The database stores the corresponding relationship between the flow deviation and the current process yield.
[0034] Compared with the prior art, the technical solution of the present invention can achieve at least one of the following beneficial effects:
[0035] 1. The etching gas flow in the gas path after the final valve is obtained by presetting a detection node on the gas path between the final valve and the chamber, that is, the second gas flow data, to determine the actual gas flow entering the etching chamber, and the gas flow set by the final valve, that is, the first gas flow data, to determine the theoretical gas flow entering the etching chamber that meets the actual etching requirements and wafer yield requirements; and then, according to the degree of deviation between the actual gas flow and the theoretical gas flow, control the current etching process, such as etching time, whether etching is terminated, etc., so as to avoid the inherent error and the corrosion of the valve by the plasma gas, causing the gas flow deviation to adversely affect the wafer yield, thereby improving the yield.
[0036] 2. Taking the actual gas flow rate collected, i.e. the second gas flow rate data, the flow deviation of the theoretical gas flow rate and the yield corresponding to the etching process as the basic data, with the help of big data technology, we can not only obtain the flow deviation range corresponding to the specific equipment, but also the flow deviation range corresponding to the specific process flow, so as to provide more scientific basis and data support for optimizing the gas flow in the etching process, thereby improving the yield.
[0037] Other features and advantages of the present invention will be described in the following description, and part of them will become obvious from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0038] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.
[0039] Figure 1 A flow chart of an etching process control method provided by an embodiment of the present invention.
[0040] Figure 2 A schematic diagram of the structure of an etching process control device provided in an embodiment of the present invention. DETAILED DESCRIPTION
[0041] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited to these terms. These terms are only used to distinguish one element, component, region, layer or part from another region, layer or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or part discussed below can be referred to as the second element, component, region, layer or part.
[0042] With the development of science and technology, the etching size of chips has reached the nanometer level, which puts forward higher requirements on the etching accuracy to ensure the yield of wafers. In plasma etching technology, whether the gas flow of etching gas can be accurately controlled is the main factor affecting the etching accuracy. Too high gas flow will lead to excessive etching of wafers, and vice versa, it will lead to insufficient etching of wafers. Both of the above situations will reduce the yield of wafers.
[0043] The usual etching process uses an end valve to control the gas flow rate of the etching gas, so the inherent error of the end valve itself will affect the actual gas flow rate of the etching gas. In addition, plasma gas is extremely corrosive, so in the etching process, the plasma gas will continue to corrode the end valve, thereby continuously reducing the control accuracy of the gas flow rate of the etching gas until the wafer yield is affected. It is understandable that when the etching size is larger than the nanometer level, the impact of the above errors and deviations on the wafer yield is very small, or even negligible. However, as the etching size continues to decrease, the above errors and deviations gradually become non-negligible factors for the wafer yield. Therefore, in order to solve the above problems, an embodiment of the present invention provides an etching process control method, such as Figure 1 As shown, the following steps are included:
[0044] Step 101, receiving an etching start instruction.
[0045] In the embodiment of the present invention, after the etching process is started, the actual gas flow rate and the ideal gas flow rate are monitored in real time.
[0046] Step 102, according to the etching start instruction, obtain the first gas flow data from the final valve, and obtain the actual gas flow, that is, the second gas flow data, from the preset detection node.
[0047] In the embodiment of the present invention, the first gas flow data is a parameter pre-set on the final valve. The parameters set on the final valve may be, but are not limited to, gas flow, mixed gas pressure, and partial pressure of each component. The second gas flow data is a parameter obtained from the etching gas transmission channel. The obtained parameter is related to the type of flow meter. For example, for a gas mass flow meter, its working principle is to use thermal measurement to measure the flow rate by the molecular mass taken away by the split molecules. At this time, the second gas flow data is the mass flow rate of the gas.
[0048] Step 103: Determine the flow deviation between the theoretical air flow and the actual air flow according to the first air flow data and the second air flow data.
[0049] Step 104, controlling the current etching process according to the relationship between the flow deviation and the preset value range.
[0050] In the embodiment of the present invention, the control of the etching process mainly includes three modes:
[0051] When the flow rate deviation is within the preset value range, the current etching process is maintained.
[0052] When the flow deviation is greater than the maximum endpoint value of the preset value range, the current etching process is terminated.
[0053] When the flow deviation is less than the minimum endpoint value of the preset value range, the gas flow rate of the current etching process is increased. In the embodiment of the present invention, the gas flow rate of the current etching process can be increased by increasing the opening of the final valve.
[0054] By the above method, the yield reduction caused by excessive flow rate can be effectively avoided. In addition, in another embodiment of the present invention, as long as the flow rate deviation value is not within the preset value range, the current etching process can be terminated so that the staff can adjust the process program in time.
[0055] It can be deduced from the above embodiments that how to set the flow deviation range is a key step in the implementation of the present application. In the embodiments of the present invention, the flow deviation is not a fixed value, but a variable value. There are three main factors that lead to the change of flow deviation: etching equipment, actual gas flow measurement equipment and etching process.
[0056] 1. Etching equipment
[0057] First of all, different etching equipment must have different fixed errors, so the flow deviations corresponding to different etching equipment must be different.
[0058] Secondly, the longer the equipment is used, the greater the corrosion of the corresponding plasma gas on the final valve, resulting in increasing flow deviation. Therefore, for the same equipment, the longer it is used, the corresponding flow deviation of the equipment. For example, for the same etching equipment, the corrosion degree of its final valve after two years of use is greater than that of its final valve after one year of use.
[0059] 2. Etching process
[0060] For etching process, usually, the larger the etching dimension is, the larger the maximum allowable deviation is. For example, when the etching dimension accuracy requirement is ±0.1% of the standard value, when the etching dimension standard value is 100nm, the maximum allowable deviation is 0.1nm, and when the etching dimension standard value is 10nm, the maximum allowable deviation is 0.01nm.
[0061] The greater the gas flow rate required in the process, the greater the maximum allowable deviation. For example, if the gas flow accuracy requirement is ±0.1% of the standard value, when the gas flow standard value is 100, the maximum allowable deviation is 0.1, and when the gas flow standard value is 10, the maximum allowable deviation is 0.01.
[0062] 3. Equipment for measuring actual airflow
[0063] For the measurement equipment of actual airflow, different acquisition equipment has different measurement accuracy, which ultimately leads to different actual airflow measured. The measurement accuracy of the acquisition equipment is related to the measurement method and equipment material.
[0064] In summary, there are many factors affecting flow deviation, so it is not easy to determine the value range of flow deviation. Based on the above facts, the embodiment of the present invention proposes to determine the value range of flow deviation by big data. The specific scheme is as follows:
[0065] a. Collect basic data
[0066] Determine the yield of each wafer after etching, and store the flow deviation and yield in correspondence. By storing the flow deviation and yield in correspondence, a corresponding relationship between the yield and the flow deviation is established, thereby providing a data basis for determining the value range of the flow deviation using the yield.
[0067] It should be noted that the objects of basic data collection are the yield of a single wafer, the flow deviation corresponding to all etching equipment, and the flow deviation corresponding to all etching processes. In an already started etching equipment or etching process, its flow deviation is usually unchanged. For example, there are three etching equipment A, B, and C, which execute processes M, N, and P respectively. Under the condition that the etching equipment is A and the etching process is M, the yield and flow deviation of a single wafer are uniquely determined. There are 9 combinations of the above-mentioned etching equipment and etching processes, which means that up to 9 corresponding relationships between flow deviations and yields are collected.
[0068] b. Use basic data to determine the range of flow deviation
[0069] First, the basic data collected are classified according to the etching equipment dimension and the etching process dimension. In the actual operation process, the measurement equipment of the actual gas flow rate uses the same model, and the measurement equipment usually has a high accuracy, so the influence of the measurement equipment on the flow deviation can be ignored.
[0070] It should be noted that the basic data of the etching equipment dimension refers to the corresponding relationship between the flow deviation and yield of the same etching equipment under multiple different etching process conditions. The basic data of the etching process dimension refers to the corresponding relationship between the flow deviation and yield of the same etching process condition on multiple different etching equipment.
[0071] For the etching equipment dimension, the first value range is determined according to the corresponding relationship between the flow deviation and the yield corresponding to the etching equipment. The first value range is applicable to the flow deviation between the theoretical gas flow and the actual gas flow corresponding to the etching equipment. Specifically, the flow deviation corresponding to the yield that does not meet the standard is eliminated, and the remaining flow deviation is used to obtain the first value range of the flow deviation. For example, etching equipment A etches 5 wafers under 5 different process conditions, and its flow deviation and yield are shown in Table 1:
[0072] Table 1 Flow rate deviation and yield of 5 wafers etched under 5 different process conditions
[0073]
[0074] Assuming that the wafer yield is required to be greater than 95%, the flow deviation corresponding to the yield of 90% is eliminated, and the remaining flow deviation is used to obtain the first value range of [132.1, 134.2].
[0075] For the etching process dimension, the second value range is determined according to the corresponding relationship between the flow deviation and the yield corresponding to the etching process. The second value range is applicable to the flow deviation between the theoretical gas flow and the actual gas flow corresponding to the etching process. Specifically, the flow deviation corresponding to the yield that does not meet the standard is eliminated, and the remaining flow deviation is used to obtain the second value range of the flow deviation. For example, 5 wafers were etched on 5 etching devices using etching process L, and their flow deviations and yields are shown in Table 2:
[0076] Table 2 Flow rate deviation and yield of 5 wafers etched under the same process conditions
[0077]
[0078] Assuming that the wafer yield is required to be greater than 95%, the flow deviation corresponding to the yield of 92.7% is eliminated, and the remaining flow deviation is used to obtain the first value range of [131.7, 133.1].
[0079] The above embodiment determines the value range of the flow deviation from two dimensions respectively. In order to further accurately determine the value range of the flow deviation, the embodiment of the present invention combines the two dimensions to obtain a newly determined flow deviation, that is, determines the intersection of the first value range and the second value range as the preset value range. It should be noted that in order to determine the preset value range from two dimensions, it is necessary to determine that the corresponding etching process can be used on the corresponding etching equipment. Taking the data in Table 1 and Table 2 as an example, when the etching process L can be applied on the etching equipment A, the preset value range is determined to be [132.1, 133.1], so as to ensure that when the etching equipment is used to run the corresponding etching process, the gas flow will not be too much or too little.
[0080] In summary, the first value range and the second value range can be used as the preset value range alone, or can be combined with each other to obtain the preset value range. It can be seen that the technical solution provided by the embodiment of the present invention can set the preset value range from multiple dimensions, and can even take into account the etching process and etching equipment.
[0081] Since the embodiment of the present invention acquires the latest correspondence between yield and gas flow in real time, and updates the basic data in real time, it is convenient to update the first value range and the second value range using big data methods in the subsequent process, thereby completely solving the problem of reduced yield caused by the degree of corrosion of the final valve. In addition, when problems occur with the wafer in the later stage, the etching process and etching equipment of the wafer can be traced through the stored basic data, and the etching process and etching equipment can be adjusted according to the problems. For example, after the wafer is sold to the customer, the customer will find that the wafer has defects during the specific application process, and will feedback the situation to the wafer manufacturer. The manufacturer can analyze which step of etching has problems or which etching equipment has problems based on the previously stored basic data, and finally optimize the etching equipment or etching process with problems.
[0082] The embodiment of the present invention provides an etching process control device, including: a database, a signal converter, a gas flow meter and a controller;
[0083] like Figure 2 As shown, after the plasma gas source generates plasma gas, the plasma gas is mixed by the gas flow management device to obtain plasma gas, and the mixed gas is delivered to the etching chamber through the final valve and the etching gas delivery pipeline. The gas flow meter is set at a preset detection node, and the detection node is set on the side of the etching gas delivery pipeline close to the gas inlet of the etching chamber.
[0084] The controller is respectively connected to the final valve and the gas flow meter, and is used to obtain the first gas flow data from the final valve and the second gas flow data from the gas flow meter; according to the first gas flow data and the second gas flow data, the flow deviation between the theoretical gas flow and the actual gas flow is determined; according to the relationship between the flow deviation and the preset value range, the current etching process is controlled.
[0085] One end of the signal converter is connected to the gas flow meter, and the other end is connected to the controller; when the data format used by the gas flow meter is different from the data format used by the controller, the signal converter is used to convert the second gas flow data from the data format used by the gas flow meter to the data format used by the controller. For example, the second gas flow data may be parameters such as voltage and current, so the signal converter needs to convert the second gas flow data into actual gas flow values according to the functional relationship, and the controller then determines the flow deviation.
[0086] The database stores the corresponding relationship between flow deviation and current process yield.
[0087] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.
Claims
1. An etching process control method, characterized in that: include: receiving an etching start instruction; According to the etching start instruction, first gas flow data is obtained from the final valve, and second gas flow data is obtained from a preset detection node; wherein the final valve is used to control the gas flow of the etching gas, the first gas flow data is pre-set in the final valve, and the second gas flow data is obtained from the etching gas transmission channel; Determining a flow deviation between a theoretical air flow and an actual air flow according to the first air flow data and the second air flow data; Controlling the current etching process according to the relationship between the flow deviation and the preset value range; The preset value range is determined by the following method: Collecting basic data, the basic data including: the yield of each etched wafer, the flow deviation corresponding to all etching equipment, and the flow deviation corresponding to all etching processes; storing the flow deviation in correspondence with the yield; The basic data are classified according to the etching equipment dimension and the etching process dimension; wherein the basic data of the etching equipment dimension refers to the corresponding relationship between the flow deviation and the yield of the same etching equipment under multiple different etching process conditions, and the basic data of the etching process dimension refers to the corresponding relationship between the flow deviation and the yield of the same etching process condition on multiple different etching equipment; Determining the preset value range according to the corresponding relationship between the flow deviation and the yield rate includes: With respect to the etching equipment dimension, a first value range is determined according to the corresponding relationship between the flow deviation and the yield rate corresponding to the etching equipment, and the first value range is applicable to the flow deviation between the theoretical gas flow and the actual gas flow corresponding to the etching equipment; With respect to the etching process dimension, a second value range is determined according to the corresponding relationship between the flow deviation and the yield corresponding to the etching process, and the second value range is applicable to the flow deviation between the theoretical gas flow and the actual gas flow corresponding to the etching process; The preset value range includes a first value range and / or a second value range.
2. The method according to claim 1, characterized in that The controlling the current etching process according to the relationship between the flow deviation and the preset value range includes: When the flow rate deviation is within the preset value range, maintaining the current etching process; When the flow rate deviation is greater than the maximum endpoint value of the preset value range, terminating the current etching process; When the flow deviation is less than the minimum endpoint value of the preset value range, the gas flow rate of the current etching process is increased.
3. The method according to claim 1, characterized in that The method further comprises: The preset value range includes a first value range; The first value range is determined according to the flow deviation and yield corresponding to the etching equipment.
4. The method according to claim 1, characterized in that: The method further comprises: The preset value range includes a second value range; The second value range is determined according to the flow deviation and yield corresponding to the etching process.
5. The method according to claim 1, characterized in that The determining the preset value range according to the corresponding relationship between the flow deviation and the yield rate includes: Determining the first value range according to the flow deviation and yield rate corresponding to the etching equipment; Determining the second value range according to the flow deviation and yield corresponding to the etching process; Determine the intersection of the first value range and the second value range as the preset value range.
6. An etching process control device, used to implement the control method according to any one of claims 1 to 5, characterized in that: include: Gas flow meters and controllers; The gas flow meter is arranged at a preset detection node, and the detection node is arranged on a side of the etching gas delivery pipeline close to the gas inlet of the etching chamber; The controller is respectively connected to the final valve and the gas flow meter, and is used to obtain the first gas flow data from the final valve and the second gas flow data from the gas flow meter; based on the first gas flow data and the second gas flow data, the flow deviation between the theoretical gas flow and the actual gas flow is determined; based on the relationship between the flow deviation and the preset value range, the current etching process is controlled.
7. The device according to claim 6, characterized in that The device further comprises: a signal converter; One end of the signal converter is connected to the gas flow meter, and the other end is connected to the controller; When the data format used by the gas flow meter is different from the data format used by the controller, the signal converter is used to convert the second gas flow data from the data format used by the gas flow meter to the data format used by the controller.
8. The device according to any one of claims 6 to 7, characterized in that: Also includes: database; The database stores the corresponding relationship between the flow deviation and the current process yield.