Wafer resistivity nondestructive testing method based on laser calibration inductance method
By integrating inductor coil and laser ranging sensor in wafer resistivity detection, real-time calibration of the lifting height solves the accuracy and cost problems of traditional detection methods, and achieving efficient and lossless wafer resistivity detection.
Patent Information
- Application Number
- CN202411636770.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-15
- Publication Date
- 2024-12-31
AI Technical Summary
Traditional wafer resistivity detection methods have problems such as damage to the wafer surface, low detection efficiency, low detection accuracy and high manufacturing cost. In particular, the four-probe method and inductance method have insufficient accuracy and cost.
Using laser calibration-based inductance method, the inductor coil and laser ranging sensor are integrated to detect the lifting height (LOD) value in real time and correct the resistivity. The XY two-axis workbench is used to realize contactless detection, reducing the cost of detection equipment. .
It improves detection accuracy and efficiency, and can achieve high-precision detection without using a high-precision positioning system. It is suitable for various conductive materials, avoids damage to the wafer surface and reduces the cost of detection equipment.
Smart Images
Figure CN119224426A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of detection technology, and in particular relates to a nondestructive detection method for wafer resistivity based on a laser calibrated inductance method. Background Art
[0002] Wafers are the basic materials for integrated circuit manufacturing and the cornerstone of integrated circuit development. Currently, most integrated circuit chips are manufactured on wafers through bulk silicon processes. In the manufacturing process of integrated circuits, the resistivity of the wafer is an important process parameter. Therefore, it is necessary to perform high-precision and high-efficiency detection of the wafer resistivity.
[0003] At present, traditional detection methods such as the four-probe method are widely used in wafer resistivity detection due to their high accuracy and high stability. However, the four-probe method is a contact detection method. During the detection process, the contact between the probe and the wafer may cause damage and contamination to the wafer surface. In addition, the four-probe method has low detection efficiency and a small detection range, making it difficult to adapt to work scenarios that require high wafer surface integrity. Therefore, it is necessary to develop high-precision and high-efficiency non-destructive testing technology to solve the problems of traditional detection methods.
[0004] Non-contact wafer resistivity detection methods include inductance method, microwave method, laser method, etc. These methods provide fast and non-destructive methods to detect the resistivity of wafers. Among these methods, the inductance method is widely favored due to its advantages such as fast, high precision, and low cost. In the inductance method, the inductance coil is driven by an AC signal to generate an alternating induced current in the wafer, and the alternating induced current changes the impedance value of the inductance coil through mutual inductance. Different wafer resistivities correspond to different alternating induced current intensities, and the coil impedance changes differently through mutual inductance. Therefore, by detecting the impedance value of the inductance coil, the resistivity of the wafer can be measured.
[0005] The accuracy of the inductance method is mainly affected by the change of lift-off height (LOD). LOD is the distance between the inductance coil and the wafer surface. The change of LOD during the detection process will increase the detection error. Due to environmental vibration and position error during detection, the change of LOD is inevitable. In order to improve the accuracy of inductance detection, a high-precision mechanical positioning system is usually used in the traditional inductance method wafer resistivity detection to keep the LOD unchanged. Although the detection accuracy is significantly improved, the high-precision mechanical positioning system also sharply increases the manufacturing cost of the detection equipment. Summary of the invention
[0006] The present invention aims to solve the problems of damaged wafer surface, low detection efficiency, low detection accuracy, high manufacturing cost and the like in the existing wafer detection technology, and provides a wafer resistivity nondestructive detection method based on a laser calibrated inductance method. The method integrates an inductance coil and a laser ranging sensor and operates synchronously. When the inductance coil performs resistivity detection, the laser ranging sensor detects the LOD value in real time, and corrects the measured resistivity value according to the LOD value. The device can significantly improve the resistivity detection accuracy of the inductance method without using a high-precision positioning system, and greatly reduces the cost of the wafer resistivity detection device.
[0007] The present invention is achieved through the following technical solutions:
[0008] A nondestructive detection method for wafer resistivity based on a laser calibrated inductance method, comprising an XY two-axis workbench and a detection probe mounted on the XY two-axis workbench, wherein the detection probe is controlled to move to any detection position in the XY plane through the XY two-axis workbench;
[0009] The detection probe is provided with a laser distance sensor and an inductance sensor, wherein the inductance sensor is used to detect the resistivity of the wafer by an inductance method, and the laser distance sensor is used to detect the LOD value of the distance between the inductance sensor and the wafer surface;
[0010] First, calibration is performed: a standard wafer sample for calibration is selected, the resistivity ρ of the sample is known; the voltage value output by the inductance sensor at different LOD values is detected and recorded, so as to obtain the relationship between the resistivity and the output voltage value of the inductance sensor at different LOD values;
[0011] Conduct detection: For the wafer to be tested, by controlling the XY two-axis worktable and adjusting the position of the detection probe, single-point or multi-point global detection is performed at any position. The inductive sensor detects the wafer in real time and outputs the voltage value. The laser ranging sensor detects the LOD value in real time, and the resistivity value measured by the inductive sensor is corrected according to the LOD value: that is, according to the relationship between the resistivity and the output voltage value of the inductive sensor at different LOD values obtained by calibration, the resistivity of the wafer to be tested corresponding to the LOD value detected by the current laser ranging sensor in real time is obtained.
[0012] In the above technical solution, the XY two-axis workbench includes a base, an X-axis moving mechanism and a Y-axis moving mechanism. The X-axis moving mechanism is installed on the base, and the Y-axis moving mechanism is installed on the X-axis moving mechanism. The Y-axis moving mechanism is driven by the X-axis moving mechanism to move along the X-axis direction. The detection probe is installed on the Y-axis moving mechanism, and the detection probe is driven by the Y-axis moving mechanism to move along the Y-axis direction.
[0013] In the above technical solution, a first driving motor is arranged at one end of the X-axis moving mechanism as a driving source of the X-axis moving mechanism; a second driving motor is arranged at one end of the Y-axis moving mechanism as a driving source of the Y-axis moving mechanism.
[0014] In the above technical solution, a wafer table is also provided on the XY two-axis workbench, and the wafer table is fixedly mounted on the base of the XY two-axis workbench by bolts. A U-shaped groove is provided on the wafer table for placing the wafer to be inspected into the U-shaped groove.
[0015] In the above technical solution, a control system is also provided on the XY two-axis workbench for controlling the operation of the equipment.
[0016] Advantages and beneficial effects of the present invention:
[0017] High sensitivity: Able to detect resistivity changes in the range of 1×10-5—1×102Ω·cm.
[0018] Automatic calibration: The laser ranging sensor can automatically detect and calibrate the detection results when the LOD changes.
[0019] No contact required: No direct contact with the wafer is required during the inspection process, avoiding potential damage to the material surface.
[0020] Fast and efficient: It can realize overall rapid detection and improve detection efficiency.
[0021] Instant results: Results are available immediately after testing, without waiting.
[0022] Wide applicability: Applicable to various conductive materials, including ferromagnetic and non-ferromagnetic materials. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 It is a structural schematic diagram of the inductive method wafer high-precision non-destructive testing equipment based on laser calibration function of the present invention.
[0024] Figure 2 It is a flow chart of the detection method of the nondestructive testing equipment of the present invention.
[0025] Figure 3 This is the detection result of the inductive sensor calibrated with a laser ranging sensor.
[0026] Figure 4 This is the detection result of the inductive sensor without calibration of the laser ranging sensor.
[0027] Figure 5 It is a flow chart of the detection process method of the nondestructive testing equipment of the present invention.
[0028] Figure 6This is a schematic diagram of the upper computer detection operation software interface for this device. In the figure, the left side is the communication setting area, parameter detection area and function area, and the right side is used for the overall characterization of the wafer during global detection.
[0029] For ordinary technicians in this field, other relevant drawings can be obtained based on the above drawings without any creative work. DETAILED DESCRIPTION
[0030] The technical solution of the present invention is further described below in conjunction with specific embodiments.
[0031] Embodiment 1
[0032] This patent proposes a high-precision non-destructive testing device and method for wafers using an inductive method based on a laser calibration function. Figure 1 , including an XY two-axis worktable 1 and a detection probe 2 installed on the XY two-axis worktable. The XY two-axis worktable 1 can control the detection probe 2 to move to any detection position in the XY plane, thereby scanning and detecting the wafer on the XY two-axis worktable and detecting the resistivity of the wafer.
[0033] Specifically, the XY two-axis workbench 1 includes a base 101, an X-axis moving mechanism 102 and a Y-axis moving mechanism 103. The X-axis moving mechanism 102 is installed on the base 101, and the Y-axis moving mechanism 103 is installed on the X-axis moving mechanism 102. The X-axis moving mechanism 102 drives the Y-axis moving mechanism 103 to move along the X-axis direction as a whole. The detection probe 2 is installed on the Y-axis moving mechanism 103, and the Y-axis moving mechanism 103 drives the detection probe 2 to move along the Y-axis direction. Then, through the combined action of the X-axis moving mechanism 102 and the Y-axis moving mechanism 103, the detection probe 2 is moved to any position in the XY plane. Further, a first driving motor 1021 is provided at one end of the X-axis moving mechanism 102 as a driving source of the X-axis moving mechanism; and a second driving motor 1031 is provided at one end of the Y-axis moving mechanism 103 as a driving source of the Y-axis moving mechanism.
[0034] The detection probe 2 is provided with a laser ranging sensor 201 and an inductance sensor 202, wherein the inductance sensor 202 is used to detect the resistivity of the wafer by the inductance method (the inductance method is that an AC signal drives an inductance coil to generate an alternating induced current in the wafer, and the alternating induced current changes the impedance value of the inductance coil through mutual inductance. Different wafer resistivities correspond to different alternating induced current intensities, and the coil impedance changes differently through mutual inductance. Therefore, by detecting the impedance value of the inductance coil, the resistivity of the wafer can be measured); the laser ranging sensor 201 is used to detect the distance between the inductance sensor 202 and the wafer surface, that is, the lift-off height (LOD). When the inductance sensor performs resistivity detection, the laser ranging sensor 201 will detect the LOD value in real time, and according to the LOD value, correct the resistivity value measured by the inductance sensor. After the detection is completed, the data is sent to the PC end, thereby realizing rapid detection of the wafer resistivity.
[0035] A wafer table 3 is also provided on the XY two-axis workbench 1. The wafer table 3 is fixedly mounted on the base 101 of the XY two-axis workbench 1 by bolts. A U-shaped groove is provided on the wafer table 3 for placing the wafer to be inspected into the U-shaped groove.
[0036] A control system 4 is also provided on the XY two-axis workbench 1 for controlling the operation of the device.
[0037] The detection method of the inductive wafer high-precision non-destructive testing equipment based on the laser calibration function of the present invention is shown in the attached Figure 2 , as follows:
[0038] 1. Calibrate for the first use: select a standard wafer sample for calibration, the resistivity ρ of the sample is known; then use the detection equipment of the present invention to detect the sample, fix the sample on the wafer table 3, detect the voltage value output by the inductance sensor 202 at different LOD values and record it, so as to obtain the relationship between the resistivity and the output voltage value of the inductance sensor at different LOD values.
[0039] 2. Detection: For the wafer to be tested, fix the sample on the wafer table 3, and adjust the position of the detection probe 2 by controlling the XY two-axis workbench 1 to perform single-point or multi-point global detection at any position. The inductance sensor 202 detects the wafer in real time and outputs the voltage value. The laser ranging sensor 201 detects the LOD value in real time, and corrects the resistivity value measured by the inductance sensor according to the LOD value: that is, according to the relationship between the resistivity and the output voltage value of the inductance sensor at different LOD values obtained by calibration, the resistivity of the wafer to be tested corresponding to the LOD value detected in real time by the current laser ranging sensor 201 is obtained.
[0040] See attached Figure 3, is the detection result of the inductive sensor calibrated with the laser ranging sensor of the present invention. It can be seen that there is no difference in the detection results under static and dynamic conditions; and the attached Figure 4 This is the detection result of the inductive sensor without laser ranging sensor calibration. It can be seen that dynamic conditions have a significant impact on the detection results.
[0041] Embodiment 2
[0042] Based on the first embodiment, this embodiment further provides a set of detection process methods, see the attached Figure 5 , the specific process is as follows:
[0043] S1: Turn on the power switch to connect the power.
[0044] S2: Open the upper computer detection operation software interface (see attached Figure 6 ).
[0045] S3: Perform software communication settings, set the serial port number to COM5, the baud rate to 9600, and the check bit to NONE.
[0046] S4: Place the wafer to be tested on the wafer stage and select single-point detection or global detection as needed.
[0047] S5: Single point detection:
[0048] S5.1: Enter the detection coordinate X and Y values in the software parameter detection area;
[0049] S5.2: Click single point movement, and the detection probe will automatically move to the point to be tested according to the set detection coordinates;
[0050] S5.3: Click on Detect, the detection probe performs a single-point detection, and the detection result is displayed on the software;
[0051] S5.4: Complete a single point detection.
[0052] S6: Global detection:
[0053] S6.1: Click Auto Detect;
[0054] S6.2: The detection probe automatically returns to the initial position;
[0055] S6.3: The detection probe performs global detection on the entire wafer according to the preset path. After the detection probe reaches a point, it automatically detects 10 times and takes the average value. Then, different color blocks are displayed according to the voltage of each point. These color blocks are used to characterize the entire wafer.
[0056] S6.4: Complete a global detection.
[0057] The above description is only used to illustrate the present invention, and is not intended to limit the present invention to the structure and scope of use shown and described. Therefore, all corresponding modifications and equivalents made within the spirit and principle of the present invention belong to the patent scope applied for by the present invention.
Claims
1. A nondestructive testing method for wafer resistivity based on laser calibrated inductance method, characterized in that: It includes an XY two-axis workbench and a detection probe installed on the XY two-axis workbench, and the detection probe is controlled by the XY two-axis workbench to move to any detection position in the XY plane; The detection probe is provided with a laser distance sensor and an inductance sensor, wherein the inductance sensor is used to detect the resistivity of the wafer by an inductance method, and the laser distance sensor is used to detect the LOD value of the distance between the inductance sensor and the wafer surface; First, calibration is performed: a standard wafer sample for calibration is selected, the resistivity ρ of the sample is known; the voltage value output by the inductance sensor at different LOD values is detected and recorded, so as to obtain the relationship between the resistivity and the output voltage value of the inductance sensor at different LOD values; Conduct detection: For the wafer to be tested, by controlling the XY two-axis worktable and adjusting the position of the detection probe, single-point or multi-point global detection is performed at any position. The inductive sensor detects the wafer in real time and outputs the voltage value. The laser ranging sensor detects the LOD value in real time, and the resistivity value measured by the inductive sensor is corrected according to the LOD value: that is, according to the relationship between the resistivity and the output voltage value of the inductive sensor at different LOD values obtained by calibration, the resistivity of the wafer to be tested corresponding to the LOD value detected by the current laser ranging sensor in real time is obtained.
2. The wafer resistivity nondestructive testing method based on laser calibrated inductance method according to claim 1 is characterized in that: The XY two-axis workbench includes a base, an X-axis moving mechanism and a Y-axis moving mechanism. The X-axis moving mechanism is installed on the base, and the Y-axis moving mechanism is installed on the X-axis moving mechanism. The Y-axis moving mechanism is driven by the X-axis moving mechanism to move along the X-axis direction. The detection probe is installed on the Y-axis moving mechanism, and the detection probe is driven by the Y-axis moving mechanism to move along the Y-axis direction.
3. The wafer resistivity nondestructive testing method based on laser calibrated inductance method according to claim 1, characterized in that: A first driving motor is arranged at one end of the X-axis moving mechanism as a driving source of the X-axis moving mechanism; a second driving motor is arranged at one end of the Y-axis moving mechanism as a driving source of the Y-axis moving mechanism.
4. The wafer resistivity nondestructive testing method based on laser calibrated inductance method according to claim 1, characterized in that: A wafer table is also provided on the XY two-axis workbench for placing wafers.
5. The wafer resistivity nondestructive testing method based on laser calibrated inductance method according to claim 4 is characterized in that: The wafer table is fixedly mounted on the base of the XY two-axis workbench by means of bolts.
6. The method for nondestructive testing of wafer resistivity based on laser calibrated inductance method according to claim 4, characterized in that: A U-shaped groove is arranged on the wafer table, and is used for placing the wafer to be inspected into the U-shaped groove.
7. The nondestructive testing method for wafer resistivity based on laser calibrated inductance method according to claim 1, characterized in that: A control system is also provided on the XY two-axis workbench.