Wafer infrared transmittance measuring device and measuring method

Abstract

The invention discloses a wafer infrared transmittance measuring device and method, and the device employs a heat preservation box body which is a closed box body, and can guarantee the consistency of the internal environment temperature after full isothermal treatment. A surface source black body is arranged in the heat preservation box body as a radiation background; the temperature of the surface source black body can be randomly set by a user; a tested wafer parallel to the surface source black body is arranged at a position, close to the surface source black body, in the heat preservation box body; the shooting end of the infrared camera faces the wafer to be measured, the distance between the shooting end of the infrared camera and the wafer to be measured meets the requirement that the shooting range completely envelops the whole wafer to be measured, and the wafer to be measured is measured by adopting a full-screen method. During measurement, different working temperature points are set, an infrared camera is used for sampling the whole wafer to be measured for multiple times, obtained data are fitted through a computer, and finally the infrared band average transmittance value of the wafer to be measured is obtained. The problems that an existing wafer infrared transmittance measuring method is high in cost and complex in operation can be solved.

Description

Technical Field

[0001] This invention relates to the field of wafer inspection technology, and in particular to a wafer infrared transmittance measuring device and method. Background Technology

[0002] Wafer infrared transmittance testing plays a crucial role in the semiconductor manufacturing industry, mainly involving quality control and defect detection, thin film layer property analysis, and process monitoring and optimization.

[0003] In quality control and defect detection, wafer infrared transmittance testing can be used to identify the uniformity and integrity of wafer materials. By measuring the ratio of infrared light of different wavelengths that passes through the wafer, minute defects such as impurities, abnormal crystal structures, or cracks inside the wafer can be revealed, ensuring the electrical performance and reliability of the wafer.

[0004] In the analysis of thin film properties, wafer infrared transmittance testing can analyze the quality and uniformity of thin films deposited on the wafer surface. By measuring the infrared transmittance of the wafer, it is helpful to optimize process parameters and ensure the expected function of the thin film layer.

[0005] In terms of process monitoring and optimization, wafer infrared transmittance detection serves as an important indicator for process monitoring. By comparing the wafer infrared transmittance before and after different process steps, the effectiveness of the process can be comprehensively evaluated, process problems can be identified and adjusted in a timely manner, and production efficiency and yield can be improved.

[0006] Therefore, a simple and inexpensive infrared transmittance detection method can not only improve the detection efficiency of wafer infrared transmittance, but also better ensure the product quality of the produced wafers.

[0007] Common methods for measuring infrared transmittance include Fourier transform and transmission spectroscopy.

[0008] The Fourier transform method involves using an infrared detector to receive the light signal from an infrared source, modulated by a Michelson interferometer, and transmitted through a sample under test. A computer system then performs a Fourier transform to calculate the infrared transmittance of the sample. This method is the most standard for infrared transmittance testing, but it is not suitable for measuring thin plates.

[0009] Transmission spectroscopy involves collecting the signal responses of a sample under illumination with and without a sample using a spectrometer, and then calculating the ratio of these responses to obtain the transmittance of the sample. Its disadvantages include the need for an integrating sphere to assist in receiving the transmitted light signal for samples with rough surfaces, the requirement for specialized technicians for operation and maintenance, and relatively high costs.

[0010] Therefore, how to solve the problems of high cost and complex operation of existing wafer infrared transmittance measurement methods has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0011] In view of the above-mentioned deficiencies of the prior art, the present invention provides a wafer infrared transmittance measuring device and measuring method, the purpose of which is to solve the problems of high cost and complex operation of the existing wafer infrared transmittance measuring methods.

[0012] To achieve the above objectives, the present invention discloses a wafer infrared transmittance measuring device, comprising an infrared camera disposed inside an insulated box, a wafer to be measured, and a surface source blackbody.

[0013] The insulated box is a closed box, which ensures the consistency of the internal ambient temperature after sufficient isothermal treatment.

[0014] The heat-insulating box has a flat inner wall with the surface source blackbody as a radiation background.

[0015] The temperature of the surface-source blackbody can be set arbitrarily by the user.

[0016] Inside the insulation box, near the blackbody, there is a wafer to be tested, parallel to the blackbody.

[0017] The wafer under test has one side facing the blackbody source and the other side facing the infrared camera;

[0018] The infrared camera's shooting end is directed towards the wafer under test, and the distance between the camera and the wafer under test is such that the shooting range completely covers the entire wafer under test. The full-screen method is used to measure the wafer under test.

[0019] Preferably, the wafer to be tested is placed behind the wafer tray and is detachably placed inside the insulation box.

[0020] More preferably, a wafer tray support frame is provided inside the insulation box at a position corresponding to the perimeter of the wafer tray.

[0021] Preferably, the size of the wafer being tested is 4 inches, 6 inches, 8 inches, or 12 inches.

[0022] The present invention also provides a method for measuring the infrared transmittance of a wafer. Using the above-mentioned wafer infrared transmittance measuring device, by setting different working temperature points of the surface source blackbody suitable for the wafer under test, the entire wafer under test is sampled multiple times using an infrared camera, and the obtained data is then fitted by a computer to finally obtain the average infrared transmittance value of the wafer under test.

[0023] Preferably, the steps include:

[0024] Step 1: Set the temperature of the surface source blackbody to T0;

[0025] Step 2: After the surface source blackbody reaches T0, maintain the temperature for t0 time to ensure that the temperature inside the insulation box is uniform and stable.

[0026] Step 3: Open the insulated box, quickly place the wafer tray inside, and close the door of the insulated box.

[0027] Step 4: Take a picture with the infrared camera and save the data. At this time, the radiation energy P0 of the blackbody source is obtained when the wafer under test is not placed.

[0028] Step 5: Quickly remove the wafer tray and close the door of the insulation box, and continue insulation for time t1.

[0029] Step 6: After the ambient temperature of the wafer tray and the outside of the insulation box is sufficiently equalized, place the wafer to be tested on the wafer tray, open the insulation box, quickly put the wafer tray in, and close the door of the insulation box.

[0030] Step 7: Take a picture with the infrared camera and save the data. At this time, the radiation energy Q of the black body transmitted through the wafer under test is obtained.

[0031] Step 8: Quickly remove the wafer tray and close the door of the insulated box;

[0032] Step 9: Set the temperature of the surface source blackbody to multiple different temperatures, and repeat steps 3 to 8 until data that can be fitted by the computer is obtained.

[0033] Step 10: Obtain infrared transmittance data by fitting the data using the computer.

[0034] The beneficial effects of this invention are:

[0035] This invention can solve the problems of high cost and complex operation of existing wafer infrared transmittance measurement methods.

[0036] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0037] Figure 1 A schematic diagram of an embodiment of the present invention is shown.

[0038] Figure 2 A flowchart of a measurement method according to an embodiment of the present invention is shown.

[0039] Figure 3 This diagram illustrates the principle of a computer performing a fitting process according to an embodiment of the present invention.

[0040] Figure 4 This invention illustrates, in one embodiment, the radiation energy P of a blackbody radiation surface collected by a camera at different temperature points. 01 To P 0n and the radiation energy Q1 to Q through the tested wafer n . Detailed Implementation

[0041] Example

[0042] like Figure 1 As shown, the wafer infrared transmittance measuring device includes an infrared camera 6, a wafer 3 to be measured, and a blackbody 2, all housed in an insulated enclosure 1.

[0043] Among them, the insulation box 1 is a closed box, which ensures the consistency of the internal ambient temperature after the insulation box 1 has been fully isothermalized.

[0044] A surface source blackbody 2 is provided on a flat inner wall inside the insulated box 1 as a radiation background;

[0045] The temperature of the surface-source blackbody 2 can be set arbitrarily by the user;

[0046] Inside the insulation box 1, near the surface source blackbody 2, there is a test wafer 3 that is parallel to the surface source blackbody 2;

[0047] The wafer under test 3 has one side facing the blackbody 2 and the other side facing the infrared camera 6;

[0048] The infrared camera 6 is positioned so that its shooting end is facing the wafer 3 under test. The distance between the infrared camera 6 and the wafer 3 under test is such that the shooting range completely covers the entire wafer 3 under test. The full-screen method is used to measure the wafer 3 under test.

[0049] The present invention uses a closed, insulated box 1 as a stable measurement environment. After sufficient isothermal treatment, the consistency of the ambient temperature can be guaranteed, providing a stable measurement environment for the wafer 3 under test and eliminating the influence of surrounding environmental disturbances on the measurement results.

[0050] This invention uses a surface-source blackbody 2 as a stable radiation background, and the temperature can be set arbitrarily by the user, providing a stable measurement background for the wafer 3 under test. This can eliminate the interference caused by the unstable radiation background on the measurement results, resulting in higher measurement accuracy and repeatability.

[0051] The infrared camera 6 of this invention uses the full-screen method to measure and analyze the entire three sides of the wafer under test, eliminating the influence of extreme values ​​on the measurement results.

[0052] The distance between the infrared camera 6 and the wafer 3 under test meets the requirement that the shooting range completely covers the entire wafer 3 under test.

[0053] In some embodiments, the wafer 3 to be tested is placed behind the wafer tray 4 and is detachably placed inside the insulation box 1.

[0054] In some embodiments, a wafer tray support frame 5 is provided inside the insulation box 1 at the position corresponding to the four edges of the wafer tray 4.

[0055] In some embodiments, the size of the wafer 3 being tested is 4 inches, 6 inches, 8 inches, or 12 inches.

[0056] In practical applications, the distance between the infrared camera 6 and the wafer 3 under test meets the requirement that the shooting range completely covers the entire wafer 3 under test. It can cover various wafers 3 under test with a size greater than 12 inches and common specifications, and can meet the measurement of infrared transmittance of wafers from 4 inches to 12 inches, with better versatility.

[0057] like Figure 2 As shown, the present invention also provides a wafer infrared transmittance measurement method. Using the wafer infrared transmittance measurement device described above, by setting different working temperature points of the surface source blackbody 2 suitable for the wafer 3 under test, the infrared camera 6 samples the entire wafer 3 under test multiple times, and then the obtained data is fitted by a computer to finally obtain the average transmittance value of the infrared band of the wafer 3 under test.

[0058] In some embodiments, the following steps are included:

[0059] Step 1: Set the temperature of the surface source blackbody 2 to T0;

[0060] Step 2: After the surface source blackbody 2 reaches T0, maintain the temperature for t0 time to make the temperature inside the insulation box 1 uniform and stable.

[0061] Step 3: Open the insulated box 1, quickly place the wafer tray 4 inside, and close the door of the insulated box 1.

[0062] Step 4: Take a picture with infrared camera 6 and save the data. At this time, the radiation energy P0 of the blackbody 2 without the tested wafer 3 is obtained.

[0063] Step 5: Quickly remove the wafer tray 4 and close the door of the insulation box 1, and continue insulation for time t1.

[0064] Step 6: After the ambient temperature outside the wafer tray 4 and the insulation box 1 is sufficiently equalized, place the wafer 3 to be tested on the wafer tray 4, open the insulation box 1, quickly put in the wafer tray 4, and close the door of the insulation box 1.

[0065] Step 7: Take a picture with infrared camera 6 and save the data. At this time, the radiation energy Q of the blackbody 2 passing through the wafer 3 under test is obtained.

[0066] Step 8: Quickly remove the wafer tray 4 and close the door of the insulated box 1;

[0067] Step 9: Set the temperature of the surface source blackbody 2 to multiple different temperatures, and repeat steps 3 to 8 until data that can be fitted by a computer is obtained.

[0068] Step 10: Obtain infrared transmittance data by fitting the data using a computer.

[0069] like Figure 3 and Figure 4 As shown, in some embodiments, the computer performs the fitting process as follows:

[0070] 1. Use a camera to collect the radiation energy P of the blackbody radiation surface at different temperature points. 01～0n and the radiation energy Q passing through the wafer being tested 1～n .

[0071] 2. The collected data is fitted using the least squares method to obtain the function of Q with respect to P0: Q = ηP0 + η + C;

[0072] Where η is the transmittance parameter of the wafer under test, and C is a constant.

[0073] This invention analyzes the collected raw data and removes interfering extreme value regions, effectively avoiding the interference of non-uniformity on the analysis results. The specific principle is as follows:

[0074] like Figure 3 As shown, where,

[0075] P0: Radiation energy of the blackbody's radiating surface, corresponding to the gray level when only the blackbody is sampled;

[0076] η: Total transmittance of the wafer;

[0077] P1: Blackbody radiation energy transmitted through the wafer, P1 = P0 × η;

[0078] P2: The self-radiation energy of the wafer, which can be regarded as constant when the ambient temperature is constant, P2 = C1;

[0079] P3: The energy reflected from the wafer surface into the camera. When the ambient temperature is constant, it can be regarded as a constant, P3 = C2.

[0080] Therefore, when a wafer is available, the total energy J that the camera can theoretically receive is:

[0081] J=P1+P2+P3=P0×η+C1+C2=P0×η+C

[0082] At a constant ambient temperature, for the same wafer, both its self-radiated energy and the energy reflected from the wafer surface into the camera can be considered constant. In this case, the energy J and P0 theoretically received by the camera have a linear relationship. By setting the blackbody surface temperature to different points, J at these different temperatures can be measured. (1～n) and P 0(1～n) .

[0083]

[0084] make The above formula can then be written as:

[0085] Y = X·Z

[0086] The actual energy received by the camera is:

[0087]

[0088] If the least squares method is used for fitting, then

[0089] M = ||YQ|| 2 =||X·ZQ|| 2 =(X·ZQ) T ·(X·ZQ)

[0090] =Z T X T XZ-Z T X T QQ T XZ+Q T Q

[0091] Differentiating the above equation with respect to Z, we get:

[0092]

[0093] The extreme value can be obtained: Z = (X T X) -1 X T Q

[0094] Therefore, the transmittance η and constant C can be calculated from the radiation energy P0 of the blackbody radiation surface received by the camera at different temperature points and the radiation energy Q of the blackbody passing through the wafer.

[0095] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A wafer infrared transmittance measuring device; characterized in that, It includes an infrared camera (6), a wafer under test (3), and a blackbody (2) installed inside an insulated box (1); The insulated box (1) is a closed box, which ensures the consistency of the internal ambient temperature after the insulated box (1) has been fully isothermalized. The heat-insulating box (1) has a flat inner wall with the surface source blackbody (2) as a radiation background; The temperature of the surface source blackbody (2) can be set arbitrarily by the user; Inside the insulation box (1), near the surface source blackbody (2), there is a wafer (3) to be tested that is parallel to the surface source blackbody (2); The wafer under test (3) has one side facing the blackbody (2) and the other side facing the infrared camera (6); The infrared camera (6) is positioned so that its shooting end is facing the wafer (3) under test. The distance between the infrared camera (6) and the wafer (3) under test is such that the shooting range completely covers the entire wafer (3) under test. The full-screen method is used to measure the wafer (3) under test.

2. The wafer infrared transmittance measuring device according to claim 1, characterized in that, The wafer to be tested (3) is placed behind the wafer tray (4) and is detachably placed inside the insulation box (1).

3. The wafer infrared transmittance measuring device according to claim 2, characterized in that, The insulated box (1) is provided with a wafer tray support frame (5) at the position corresponding to the four edges of the wafer tray (4).

4. The wafer infrared transmittance measuring device according to claim 1, characterized in that, The size of the wafer (3) being tested is 4 inches, 6 inches, 8 inches or 12 inches.

5. A method for measuring the infrared transmittance of a wafer, characterized in that, Using the wafer infrared transmittance measuring device as described in claim 2 or 3, by setting different working temperature points of the surface source blackbody (2) suitable for the wafer (3) under test, and then using an infrared camera (6) to sample the entire wafer (3) under test multiple times, and then fitting the obtained data through a computer, the average transmittance value of the infrared band of the wafer (3) under test is finally obtained.

6. The wafer infrared transmittance measurement method according to claim 5, characterized in that, Includes the following steps: Step 1: Set the temperature of the surface source blackbody (2) to T0; Step 2: After the surface source blackbody (2) reaches T0, keep it warm for t0 time to make the temperature inside the insulation box (1) uniform and stable. Step 3: Open the insulation box (1), quickly place the wafer tray (4) inside, and close the door of the insulation box (1); Step 4: Take a picture with the infrared camera (6) and save the data. At this time, the radiation energy P0 of the black body (2) without the wafer (3) being tested is obtained. Step 5: Quickly remove the wafer tray (4) and close the door of the insulation box (1) to continue insulation for time t1; Step 6: After the ambient temperature outside the wafer tray (4) and the insulation box (1) is sufficiently equalized, place the wafer (3) to be tested on the wafer tray (4), open the insulation box (1), quickly put the wafer tray (4) in, and close the door of the insulation box (1). Step 7: Take a picture with the infrared camera (6) and save the data. At this time, the radiation energy Q of the black body (2) passing through the wafer (3) under test is obtained. Step 8: Quickly remove the wafer tray (4) and close the door of the insulated box (1); Step 9: Set the temperature of the surface source blackbody (2) to multiple different temperatures, and repeat steps 3 to 8 until data that can be fitted by the computer is obtained; Step 10: Obtain infrared transmittance data by fitting the data using the computer.

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