Surface acoustic wave-based low-k film adhesion two-dimensional scanning detection device

Abstract

The invention relates to a low-k film adhesion two-dimensional scanning detection device based on surface acoustic waves, which comprises a film adhesion two-dimensional scanning detection platform, a three-dimensional electric control platform, a three-dimensional mobile sample test platform, a guide rail, an electric sliding block, a piezoelectric detector and a laser, and is characterized in that the three-dimensional electric control platform is arranged on the film adhesion two-dimensional scanning detection platform; the three-dimensional moving sample testing platform is fixed on the three-dimensional electric control platform, the plane where the three-dimensional moving sample testing platform is located is parallel to the plane where the three-dimensional moving sample testing platform is located, the guide rail is arranged on the film adhesion two-dimensional scanning detection platform, and the electric sliding block can slide on the guide rail; translation shafts of the three-dimensional electric control platform are a first shaft and a second shaft which are perpendicular to each other, and the guide rail is parallel to the second shaft. The piezoelectric detector is fixedly connected with the electric sliding block through a fixing support. The invention also provides a scanning detection method realized by the low-k film adhesion two-dimensional scanning detection device based on the surface acoustic waves.

Description

Technical Field

[0001] The invention relates to a two-dimensional scanning detection device for low-k film adhesion based on surface acoustic wave technology, which can realize two-dimensional scanning detection of low-k film adhesion in wafers of different sizes. Background Art

[0002] When a surface acoustic wave (SAW) propagates in a film / substrate layered structure, the energy of the SAW is mainly concentrated in the film. The wavelength of high-frequency surface waves is shorter, and they are more affected by the film layer, so they can better reflect the situation in the film. The wavelength of low-frequency surface waves is longer, and they are more affected by the substrate layer, so they can relatively better reflect the situation in the substrate. Obviously, when SAW propagates in a film / substrate layered structure, dispersion will occur, that is, the wave velocity of the SAW changes with the frequency of the SAW. It should be noted that the definition of "thin" film here is generally that the thickness of the film is less than the wavelength of the SAW.

[0003] The adhesion property between film and substrate is a crucial characteristic that is of concern in integrated circuit technology. Poor adhesion properties will seriously affect the reliability of the process and subsequent products. The first step is chemical mechanical polishing (CMP) in the process. Poor interlayer adhesion will lead to fracture, delamination and shedding of the film layer in the CMP process. In previous studies, the cohesive force (CZM) model was introduced into the surface acoustic wave technology to realize the detection of film adhesion. In addition, the CZM-SAW technology can achieve non-destructive, quantitative and systematic determination of the interface adhesion between film and substrate while completing the adhesion measurement. Therefore, it is considered to be an excellent method for characterizing film adhesion.

[0004] However, it should be noted that the adhesion between thin film substrates is usually caused by the instability and non-uniformity of process conditions in film forming processes such as chemical vapor deposition (CVD), physical vapor deposition (PVD), and spin coating (SOD). Therefore, the adhesion of the same wafer may only be substandard at one or two locations. If only in-situ detection is performed, it is very likely that missed detection will occur, thus affecting the reliability of subsequent products. Summary of the invention

[0005] The purpose of the present invention is to solve the deficiencies in the above-mentioned background technology, and to provide a two-dimensional scanning detection device for low-k film adhesion based on surface acoustic wave technology and a detection method. The technical solution is as follows:

[0006] A low-k film adhesion two-dimensional scanning detection device based on surface acoustic wave, comprising a film adhesion two-dimensional scanning detection platform 13, a three-dimensional electric control platform 2, a three-dimensional moving sample test platform 1, a guide rail 8, an electric slider 9, a piezoelectric detector 14, a laser 4, an optical path system and a data processing system, wherein:

[0007] The three-dimensional electric control platform is arranged on the two-dimensional scanning detection platform 13 for thin film adhesion; the three-dimensional mobile sample test platform 1 is fixed on the three-dimensional electric control platform 2, and its plane is parallel to the plane where the three-dimensional mobile sample test platform 1 is located, the guide rail 8 is arranged on the two-dimensional scanning detection platform 13 for thin film adhesion, and the electric slider 9 can slide on the guide rail 8; the translation axis of the three-dimensional electric control platform 2 is set as the first axis and the second axis perpendicular to each other, and the guide rail 8 is parallel to the second axis; the piezoelectric detector 14 is fixedly connected to the electric slider 9 through the fixed bracket 10; the optical path system is used to focus the laser emitted by the laser 4 onto the test sample; the data processing system is used to obtain the dispersion curve according to the collected surface wave signal, compare it with the theoretical dispersion curve, obtain the adhesion value of each measuring point and record it.

[0008] Furthermore, a plurality of slots for placing test samples of different sizes are provided on the three-dimensional mobile sample testing platform.

[0009] The present invention also provides a scanning detection method implemented by the two-dimensional scanning detection device for low-k film adhesion based on surface acoustic wave, and the scanning detection process includes:

[0010] 14) Place the test sample on the three-dimensional mobile sample test platform and determine the scanning route;

[0011] 15) The laser emitted by the laser passes through the optical path system and irradiates the test sample. The three-dimensional movable sample test platform and the electric slider are adjusted so that the center position of the laser focus line falls on the initial position of the laser focus point, so that the piezoelectric detection

[0012] The detector falls at the initial position of the detection point which has the same first axis coordinate as the initial position of the laser focus point;

[0013] 16) Controlling the three-dimensional electric control platform to drive the three-dimensional mobile sample test platform to move downward so that the piezoelectric detector is located above the test sample;

[0014] 17) Controlling the three-dimensional electronically controlled platform so that the laser focus point is positioned at a preset position on the test sample;

[0015] 18) Control the electric slider to drive the piezoelectric detector to locate to the same position as the first axis coordinate of the laser focus point; control the electric slider to move along the guide rail, change the second axis coordinate position of the piezoelectric detector, and locate it to the preset detection point position;

[0016] 19) Controlling the three-dimensional electric control platform to drive the three-dimensional mobile sample test platform to move upward, so that the piezoelectric detector contacts the test sample, and the first piezoelectric detector picks up the received signal to obtain the first surface acoustic wave signal;

[0017] 20) Controlling the three-dimensional electric control platform to drive the three-dimensional mobile sample test platform to move downward so that the piezoelectric detector is located above the test sample;

[0018] 21) Controlling the electric slider to drive the piezoelectric detector to be positioned to the same position as the first axis coordinate of the laser focus point in step 7);

[0019] Control the electric slider to move along the guide rail, change the second axis coordinate position of the piezoelectric detector, and locate it to the preset detection point position;

[0020] 22) Controlling the three-dimensional electric control platform to drive the three-dimensional mobile sample test platform to move upward, so that the piezoelectric detector contacts the test sample, and the second piezoelectric detector picks up the received signal to obtain the second surface acoustic wave signal;

[0021] 23) performing fast Fourier transform on the collected first surface acoustic wave signal and the second surface acoustic wave signal to obtain a dispersion curve of the measurement, comparing the dispersion curve with the theoretical dispersion curve, obtaining and recording the adhesion value of the measurement;

[0022] 24) Repeat steps 5) to 10) until the test of half of the points in a column of points on the test sample is completed;

[0023] 25) Control the three-dimensional mobile sample test platform 1 to rotate 90° clockwise through the three-dimensional electric control platform; repeat steps 5)-10) to complete.

[0024] The test of the other half of the points in one column of the test sample;

[0025] 26) Re-determine the initial position of the laser focus point and the initial position of the detection point, and repeat steps 2)-12) until the test of all points in the entire test sample is completed.

[0026] The present invention designs a movable optical path system, a movable piezoelectric detection system and a rotatable sample stage in response to the scanning detection requirements, and establishes a test device and method for two-dimensional scanning detection of low-k film adhesion, which can detect and evaluate the adhesion of the entire wafer plane of different sizes. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a two-dimensional scanning detection device for film adhesion;

[0028] Figure 2 It is a top view and side perspective view of the three-dimensional mobile sample test platform;

[0029] Figure 3 It is a schematic diagram of the sample scanning coordinates;

[0030] The figure is marked as follows: 1—three-dimensional moving sample test platform; 2—three-dimensional electric control platform; 3—test sample; 4—laser; 5—plane reflector; 6—prism; 7—cylindrical mirror; 8—guide rail; 9—electric slider; 10—fixed bracket of piezoelectric detector; 11—fixed bracket of prism and cylindrical mirror; 12—fixed bracket of plane reflector; 13—two-dimensional scanning detection platform for film adhesion; 14—piezoelectric detector; 15—12-inch test sample slot; 16—8-inch test sample slot; 17—6-inch test sample slot; 18—4-inch test sample slot; 19—2-inch test sample slot; 20—initial position of piezoelectric detector in all sample test procedures; 21—initial position of laser focus point in all sample test procedures. DETAILED DESCRIPTION

[0031] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings:

[0032] The low-k film adhesion two-dimensional scanning detection device based on surface acoustic wave of the present invention includes a film adhesion two-dimensional scanning detection platform 13, a three-dimensional electric control platform 2, a three-dimensional moving sample test platform 1, a guide rail 8, an electric slider 9, a piezoelectric detector 14, a laser 4, an optical path system and a data processing system.

[0033] The three-dimensional electric control platform 2 is arranged on the two-dimensional scanning detection platform 13 for film adhesion; the three-dimensional mobile sample test platform 1 is fixed on the three-dimensional electric control platform 2, and the plane on which the three-dimensional mobile sample test platform 1 is located is parallel to the plane on which the three-dimensional mobile sample test platform 1 is located; the guide rail 8 is arranged on the two-dimensional scanning detection platform 13 for film adhesion, and the electric slider 9 can slide on the guide rail 8; the translation axis of the three-dimensional electric control platform 2 is set as the first axis and the second axis which are perpendicular to each other, and the guide rail 8 is parallel to the second axis; the piezoelectric detector 14 is fixedly connected to the electric slider 9 through the fixed bracket 10;

[0034] A plurality of slots for placing test samples of different sizes are provided on the three-dimensional mobile sample test platform 1; Figure 2 As shown, the three-dimensional moving sample test platform 1 includes a 12-inch test sample card slot 15, an 8-inch test sample card slot 16, a 6-inch test sample card slot 17, a 4-inch test sample card slot 18, and a 2-inch test sample card slot 19; before testing, the test samples are fixed in the card slots of corresponding sizes according to their sizes. The guide rail 8, the fixing bracket 11 of the prism and cylindrical mirror, and the fixing bracket 12 of the plane reflector are all fixed on the two-dimensional scanning detection platform 13 for film adhesion. The optical path system used in the present invention is a common laser focusing optical path.

[0035] Turn on the control system of the movable piezoelectric detection system and the three-dimensional movable sample test platform, where the position control system of the movable piezoelectric detection system is composed of the guide rail 8, the electric slider 9 and the fixed bracket 10 of the piezoelectric detector, and the control system of the three-dimensional movable sample test platform is composed of the three-dimensional electric control platform 2. The initial positions of the piezoelectric detector and the laser focus point in all sample tests are shown in the attached Figure 3 First, the initial position of the laser focus is at position 21 by controlling the three-dimensional electric control platform 2, and then the movable piezoelectric detector 14 is placed at the initial position, i.e., position 20, by controlling the electric slider 9.

[0036] For test samples of different sizes, there are fixed test sites, that is, fixed test procedures. The test sites and test sequence of each sample are shown in Appendix 1. According to the size of the test sample, select the corresponding test program on the industrial computer for measurement. The basic principle for selecting test points is: evenly select points on the surface of the sample. If the test points are connected, they will be several line segments parallel to the side length of the three-dimensional mobile sample test platform 1. On each test line segment, the position of the fixed laser excitation is at the end point of the test line segment, and the measurement of the test line segment is completed by moving the position of the piezoelectric detector. During the test, first measure the central test line segment, then measure the remaining test line segments in the positive direction to the test point farthest from the center, and then measure the test line segments in the reverse direction. In this way, the scanning measurement can be completed on the test sample to ensure the reliability of the mechanical properties of the test sample.

[0037] The movement of the laser excitation point is actually completed by the three-dimensional electric control platform 2 controlling the three-dimensional mobile sample test platform 1. For example, when the laser point moves from the position (0,2) to the point (1.5,1), the three-dimensional electric control platform 2 actually controls the three-dimensional mobile sample test platform 1 to move 1.5 unit lengths in the negative direction of the x-axis, and then moves 1 unit length in the positive direction of the y-axis. Each unit length actually corresponds to 1 cm. The movement of the piezoelectric detector point in the x-axis direction is actually controlled by the three-dimensional electric control platform 2 to control the movement of the three-dimensional mobile sample test platform 1, that is, with the movement of the laser point in the x-axis direction, the change of the horizontal coordinate of the piezoelectric detector measurement point has actually been completed. The change of the vertical coordinate of the piezoelectric detector measurement point is completed by the electric slider 9. Each time the measurement point position needs to be moved, the three-dimensional electric control platform 2 will control the three-dimensional mobile sample test platform 1 to descend 1 cm to protect the piezoelectric detector from damage. After the measurement point position change is completed, the three-dimensional electric control platform 2 will control the three-dimensional mobile sample test platform 1 to rise 1 cm and contact the piezoelectric detector to complete the measurement.

[0038] Appendix 1 Measurement points and measurement routes for wafers of various sizes

[0039]

[0040]

[0041]

[0042]

[0043] The overall measurement process is as follows:

[0044] 1. Fix the sample to be tested into the test sample slot of corresponding size;

[0045] 2. Turn on the laser and adjust the heights of the prism 6 and the plane reflector 5 so that the laser can be reflected from the plane reflector 5 to the prism 6;

[0046] 3. Adjust the position of the cylindrical mirror 7 so that the laser can converge into a very fine laser line on the surface of the test sample, and the length of the laser line is about 1 cm;

[0047] 4. Adjust the three-dimensional movable sample test platform 1 and the electric slider 9 so that the center position of the laser focus line falls on the initial position No. 21, and the movable piezoelectric detector 14 falls on the initial position, i.e., No. 20;

[0048] 5. The three-dimensional electric control platform 2 controls the three-dimensional mobile sample test platform 1 to descend 1 cm;

[0049] 6. According to the scanning route of Appendix 1, adjust the three-dimensional mobile sample test platform 1 so that the center position of the laser focus line falls on the first laser excitation site;

[0050] 7. According to the scanning route of Appendix 1, adjust the movable piezoelectric detector 14 to fall at the first detector position;

[0051] 8. After adjusting to the corresponding measurement position, the three-dimensional electric control platform 2 controls the three-dimensional mobile sample test platform 1 to rise by 1 cm, and completes the pickup of the piezoelectric detector receiving signal 1;

[0052] 9. The three-dimensional electric control platform 2 controls the three-dimensional mobile sample test platform 1 to descend 1 cm;

[0053] 10. Adjust the movable piezoelectric detector 14 to move 0.4 cm in the negative direction of the y-axis;

[0054] 11. After adjusting to the corresponding measurement position, the three-dimensional electric control platform 2 controls the three-dimensional mobile sample test platform 1 to rise by 1 cm, and completes the pickup of the piezoelectric detector receiving signal 2;

[0055] 12. Perform fast Fourier transform on the collected surface acoustic wave signal 1 and surface acoustic wave signal 2 to obtain the dispersion curve of this measurement, compare it with the theoretical dispersion curve, obtain the adhesion value of this measurement and record it in the corresponding position of the software;

[0056] 13. Repeat steps 5-12 until the test of half of the points in a column is completed.

[0057] 14. The three-dimensional electric control platform 2 controls the three-dimensional mobile sample test platform 1 to rotate 90° clockwise;

[0058] 15. Repeat steps 4-12 to complete the test of the other half of the column of points.

[0059] 16. Reposition and repeat steps 4-15 until all points of the test sample are tested.

Claims

1. A two-dimensional scanning detection device for low-k film adhesion based on surface acoustic wave, comprising a two-dimensional scanning detection platform 13 for film adhesion, a three-dimensional electric control platform 2, a three-dimensional moving sample test platform 1, a guide rail 8, an electric slider 9, a piezoelectric detector 14, a laser 4, an optical path system and a data processing system, wherein: The three-dimensional electric control platform is arranged on the two-dimensional scanning detection platform 13 for thin film adhesion; the three-dimensional mobile sample test platform 1 is fixed on the three-dimensional electric control platform 2, and its plane is parallel to the plane where the three-dimensional mobile sample test platform 1 is located, the guide rail 8 is arranged on the two-dimensional scanning detection platform 13 for thin film adhesion, and the electric slider 9 can slide on the guide rail 8; the translation axis of the three-dimensional electric control platform 2 is set as the first axis and the second axis perpendicular to each other, and the guide rail 8 is parallel to the second axis; the piezoelectric detector 14 is fixedly connected to the electric slider 9 through the fixed bracket 10; the optical path system is used to focus the laser emitted by the laser 4 onto the test sample; the data processing system is used to obtain the dispersion curve according to the collected surface wave signal, compare it with the theoretical dispersion curve, obtain the adhesion value of each measuring point and record it.

2. The low-k film adhesion two-dimensional scanning detection device based on surface acoustic wave according to claim 1, characterized in that: A plurality of slots for placing test samples of different sizes are provided on the three-dimensional mobile sample testing platform 1 .

3. A scanning detection method implemented by the low-k film adhesion two-dimensional scanning detection device based on surface acoustic wave according to any one of claims 1 and 2, characterized in that: The scanning process includes: 1) Place the test sample on the three-dimensional mobile sample test platform and determine the scanning route; 2) The laser emitted by the laser passes through the optical path system and irradiates the test sample, and the three-dimensional movable sample test platform 1 and the electric slider are adjusted so that the center position of the laser focus line falls on the initial position of the laser focus point, and the piezoelectric detector falls on the initial position of the detection point with the same first axis coordinate as the initial position of the laser focus point; 3) Controlling the three-dimensional electric control platform to drive the three-dimensional mobile sample test platform to move downward so that the piezoelectric detector is located above the test sample; 4) Control the three-dimensional electronic control platform so that the laser focus point is positioned at a preset position on the test sample; 5) Control the electric slider to drive the piezoelectric detector to locate to the same position as the first axis coordinate of the laser focus point; control the electric slider to move along the guide rail, change the second axis coordinate position of the piezoelectric detector, and locate it to the preset detection point position; 6) Control the three-dimensional electric control platform to drive the three-dimensional mobile sample test platform to move up and down, so that the piezoelectric detector contacts the test sample. Picking up a signal received by the first piezoelectric detector to obtain a first surface acoustic wave signal; 7) Controlling the three-dimensional electric control platform to drive the three-dimensional mobile sample test platform to move downward so that the piezoelectric detector is located above the test sample; 8) Controlling the electric slider to drive the piezoelectric detector to be positioned to the same position as the first axis coordinate of the laser focus point in step 7); Control the electric slider to move along the guide rail, change the second axis coordinate position of the piezoelectric detector, and locate it to the preset detection point position; 9) Control the three-dimensional electric control platform to drive the three-dimensional mobile sample test platform to move up, so that the piezoelectric detector contacts the test sample. Picking up a signal received by a second piezoelectric detector to obtain a second surface acoustic wave signal; 10) performing fast Fourier transform on the collected first surface acoustic wave signal and the second surface acoustic wave signal to obtain a dispersion curve of the measurement, comparing the dispersion curve with the theoretical dispersion curve, obtaining and recording the adhesion value of the measurement; 11) Repeat steps 5) to 10) until the test of half of the points in a row of points on the test sample is completed; 12) Control the three-dimensional mobile sample test platform 1 to rotate 90° clockwise through the three-dimensional electric control platform; repeat steps 5)-10) to complete the test of the other half of the points in one column of the test sample; 13) Re-determine the initial position of the laser focus point and the initial position of the detection point, and repeat steps 2)-12) until the test of all points in the entire test sample is completed.

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