Method for detecting light transmittance of a quartz reaction chamber of an epitaxial apparatus

Abstract

The application discloses a kind of methods for detecting the transmittance of quartz reaction chamber of epitaxial equipment, including but not limited to esther200C, esther200L, LPE 3061S and LPE2061S epitaxial equipment, use external color camera with PLC industrial computer equipment to shoot the image of bell jar observation window and temperature measurement window area, select the light transmission area for analysis, divide the effective light transmission area into several microcircuits, calculate the RGB value of observation hole in each microelement area and the average value ratio of blue component and green component. By comparing the difference between the RGB value in the region and the standard value, and comparing the B / G ratio with the standard value set, the state of bell jar transmittance is identified.

Description

Technical Field

[0001] This invention relates to the field of semiconductor silicon epitaxial manufacturing, and more specifically to a method for automatic monitoring and identification of the light transmittance of a protective bell jar for silicon epitaxial equipment. Background Technology

[0002] In the field of semiconductor silicon epitaxial manufacturing, especially vapor deposition epitaxy, most processes are carried out in high-temperature and special gas environments. Therefore, a quartz protective cover is needed to isolate the growth environment from the external environment. The light transmittance of the quartz protective cover is related to the accuracy of temperature control and the defect rate. Therefore, it is necessary to measure the light transmittance of the protective cover.

[0003] Currently, most of the light transmittance testing for protective covers of silicon epitaxial equipment is based on manual periodic inspections and human observation during machine maintenance and disassembly, without achieving real-time and quantitative analysis.

[0004] Due to the high-temperature environment required for machine growth, the growth temperature is usually above 1000℃. The changes in the protective cover cannot be directly observed by the human eye. Moreover, due to the nature of spot checks, problems that occur during the manufacturing process often cannot be detected in time, resulting in significant economic and production efficiency losses. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a method for detecting the transmittance of quartz reaction chambers in epitaxial equipment based on RGB image recognition. This method can automatically monitor the transmittance of the quartz protective cover used on the epitaxial equipment, transmit the identified RGB values ​​to the controller for real-time monitoring, and provide an alarm device to reduce production efficiency losses.

[0006] This invention provides a method for detecting the transmittance of the quartz reaction cavity in an electromagnetic induction heating epitaxial device. Specifically, by performing RGB three-primary-color grayscale analysis on a true-color image of the protective cover under high-temperature growth conditions, a common industrial camera can be used for real-time monitoring of the device under high-temperature growth conditions. This method has the advantages of wide applicability, low cost, and high accuracy.

[0007] The technical solution provided by this invention is:

[0008] A method for detecting the transmittance of a quartz reaction cavity in an epitaxial device includes:

[0009] S1. Obtain images of the quartz reaction chamber observation window through real-time true-color images captured by a camera as the analysis object;

[0010] S2. Perform real-time image processing, decompose the observation window image into RGB primary color component images, and calculate the specific values ​​of the RGB three color values ​​in the observation window image;

[0011] S3. By comparing the calculated RGB values, the real-time status of the reaction chamber is determined; when the average gray value of the blue component in the identified image is greater than the set average gray value threshold of the blue component, and the green component in the identified image is greater than the set average gray value threshold of the green component, the light transmittance of the quartz reaction chamber is normal.

[0012] When the average gray value of the blue component in the identified image is less than the set average gray value threshold for the blue component, and the average gray value of the green component in the identified image is less than the set average gray value threshold for the green component, the transmittance of the quartz reaction chamber is lower than the usage requirements.

[0013] Furthermore, multiple images corresponding to time changes are acquired over a period of time, and the grayscale value changes of the primary color components in each image are analyzed to establish a curve between grayscale value and transmittance change. Standard grayscale values ​​are obtained through numerical fitting. A standardized database is also established. The RGB primary color division values ​​of the quartz reaction chamber observation window and the machine growth temperature are compared with the standard data in the standardized database to obtain the true transmittance of the reaction chamber.

[0014] Furthermore, S2 also includes,

[0015] S21. The Gige camera is selected as the communication protocol.

[0016] S22. The acquired image is processed by the PLC controller, including erosion followed by dilation to remove image interference.

[0017] S23. Search for images of the quartz reaction chamber observation window in the image using structured elements. When creating structured elements, select structured elements according to the shape area of ​​different observation windows.

[0018] S24. Construct the image of the observation window. Since the image of the observation window was reconstructed in the previous step of constructing structured elements, the shape of the observation window is calculated by the difference algorithm between the constructed image and the original image, and the area of ​​the observation window is calculated by Green's formula.

[0019] S25. Calculate the average pixel value within the observation window area. For the area of ​​the region obtained in step S24, divide the region into a finite number of elements and calculate the pixel value of each element.

[0020] S26. For the pixel values ​​calculated in S25, decompose them into RGB primary color component maps, calculate the RGB component value of each element, and obtain the average value of the RGB components of the entire observation window by area calculation.

[0021] Furthermore, S3 also includes,

[0022] S31. Compare the RGB component values ​​obtained from the observation window with the threshold values ​​set in the system to determine whether they are within the normal range.

[0023] S32. If the error exceeds the normal range, the PLC controller will issue an audible and visual alarm to alert the operator that the system is malfunctioning and requires manual intervention for repair.

[0024] Furthermore, during the establishment process, it is necessary to accumulate the changes in RGB component values ​​measured at different temperatures and with variations in transmittance in different reaction chambers, and establish a standardized database.

[0025] Furthermore, after establishing a standard database, the usage requirements for light transmittance are defined, and the upper and lower limits of light transmittance are determined.

[0026] Furthermore, selections should be made according to different temperatures, and the control line data in the standardized database should be improved after the selection is completed.

[0027] In summary, the technical solutions described in this invention have the following beneficial effects compared to existing technologies:

[0028] The technical implementation scheme adopted in this invention includes a general-purpose industrial camera and a PLC controller. These devices are highly applicable and have low cost. Compared with the previous manual inspection scheme, they have the functions of real-time measurement, online alarm and early prevention, and the actual use effect is better. Attached Figure Description

[0029] Figure 1 This is a structural schematic diagram of an example of the technical solution of the present invention;

[0030] Figure 2 This is a curve showing the change of RGB values ​​of an image taken by an industrial camera and viewed through the observation window of the reaction chamber within one cycle, as described in an example of the technical solution of this invention. Detailed Implementation

[0031] This invention discloses a method for detecting the transmittance of a quartz reaction chamber, specifically as follows:

[0032] (1) Deploy and install an industrial camera in the area of ​​the quartz reaction chamber where the light transmittance needs to be detected, and take pictures of the observation area;

[0033] (2) Image framing: The image obtained by the industrial camera is subjected to a framing algorithm to remove invalid areas. The upper limit of the effective area represents the RGB three primary color components as (255,255,255), and the lower limit represents the RGB three primary color components as (80,0,0). The effective area is then morphologically modeled to obtain the model of the desired transmittance area.

[0034] (3) Perform pixel statistics on the acquired image model. Each pixel has three primary color component images, and calculate the RGB primary color component values ​​of each pixel. Specifically, firstly, decompose the captured image into R, G, and B primary color component images, where each primary color component image consists of W×D pixels. Each pixel is represented by a gray value between 0 and 255. The average gray value of the image is calculated, which is the average value of the R, G, and B primary color components obtained in this invention. The calculation formula is as follows:

[0035]

[0036]

[0037]

[0038] k(x,y) represents the value of the Red component in the pixel; h(x,y) represents the value of the Green component in the pixel;

[0039] g(x,y) represents the value of the Blue component in the pixel;

[0040] (4) Accumulate the correspondence between RGB values ​​and temperature of quartz reaction chambers under different growth environments and establish a standard database. The establishment of the standard database involves data accumulation. Firstly, it involves accumulating the changes in RGB three primary color component values ​​of the same reaction chamber at the same temperature as the transmittance changes, calculating the changes through the above steps, and establishing a corresponding relationship spectrum. Secondly, it involves accumulating the changing trends of the calculated RGB three primary color component values ​​when the transmittance changes at different temperatures, establishing a corresponding relationship spectrum. The process is as follows:

[0041] P = f(T, Real(R, G, B))

[0042] Where: variable P is the transmittance variable of the reaction chamber, T is the temperature of the reaction chamber, and Real(R,G,B) is the RGB value group;

[0043] (5) By establishing a standard database, the RGB three primary color component values ​​corresponding to different transmittance at different temperatures are obtained, and the Realstand(R,G,B) value corresponding to the lower limit of transmittance is taken as the standard value for judgment.

[0044] (6) At temperature T1, an array of RGB three-color component values Real1(R, G, B) of the observation area of the quartz reaction chamber is obtained according to the above process. When Real1(R, G, B) < Realstand(R, G, B), the controller issues an alarm message indicating that the light transmittance has dropped below the usable lower limit and the reaction chamber needs to be cleaned.

[0045] In a preferred embodiment, the results of identifying the component values of a quartz reaction chamber at a specific temperature are as follows:

[0046] When the temperature is 1160 °C, the change in the R value component with the light transmittance is (80 - 255), the change in the G value with the light transmittance is (12 - 255), and the change in the B value component with the light transmittance is (15 - 255). Preferably, a set of RGB standard values under an acceptable light transmittance is selected as (160, 90, 90) to serve as the standard value for the change in the light transmittance of the reaction chamber at this temperature. As the usage time changes, when the measured real-time RGB component values are greater than the standard value, it indicates that the light transmittance of the reaction chamber is normal and it can continue to be used; when the measured real-time RGB component values are less than the standard value, it indicates that the reaction chamber is abnormal and needs to be cleaned immediately.

[0047] The method for detecting the light transmittance of the reaction chamber in this example is an identification method based on the determination of RGB values of true-color images. It can be observed in real time during use and has an alarm prompt function. It has a wide range of applications and good application prospects.

[0048] It is easy for those skilled in the art to understand that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for detecting the transmittance of a quartz reaction chamber of an epitaxial apparatus, characterized by, include: S1. Obtain the image of the quartz reaction chamber observation window through real-time true-color images captured by the camera as the analysis object; S2. Perform real-time image processing, decompose the observation window image into RGB primary color component images, and calculate the specific values ​​of the RGB three color values ​​in the observation window image; S3. By comparing the calculated RGB values, the real-time status of the reaction chamber is determined; when the average gray value of the blue component in the identified observation window image is greater than the set average gray value threshold of the blue component, and at the same time the green component in the identified observation window image is greater than the set average gray value threshold of the green component, the light transmittance of the quartz reaction chamber is normal. When the average gray value of the blue component in the identified observation window image is less than the set average gray value threshold of the blue component, and the average gray value of the green component in the identified observation window image is less than the set average gray value threshold of the green component, the light transmittance of the quartz reaction cavity is lower than the usage requirement. Multiple observation window images corresponding to time changes are acquired over a period of time, and the gray value changes of the primary color components in each observation window image are analyzed to establish a curve between gray value and transmittance changes. Standard gray values ​​are obtained through numerical fitting. A standardized database is also established. The RGB primary color component values ​​and machine growth temperature of the acquired quartz reaction cavity observation window images are compared with the standard data in the standardized database to obtain the true transmittance of the reaction cavity.

2. The method of claim 1, wherein the method further comprises: S3 also includes, S31. Compare the RGB component values ​​obtained from the observation window with the threshold values ​​set in the system to determine whether they are within the normal range. S32. If the error exceeds the normal range, the PLC controller will issue an audible and visual alarm to alert the operator that the system is malfunctioning and requires manual intervention for repair.

3. The method for detecting the transmittance of the quartz reaction chamber in an epitaxial device according to claim 1, characterized in that, During the establishment process, a standardized database was established by measuring the changes in RGB component values ​​at different temperatures in different reaction chambers to reflect changes in light transmittance.

4. The method of claim 3, wherein the method further comprises: After establishing a standard database, the requirements for light transmittance are defined, and the upper and lower limits of light transmittance are determined.

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