Electron beam testing equipment

Abstract

This invention provides an electron beam inspection device equipped with a wafer-carrying mechanical chuck. The wafer-carrying mechanical chuck includes: a chuck body made of a conductive material, with a bearing plane formed on its top; multiple adjustable conductive pins disposed on the chuck body, each adjustable conductive pin having an adjustable section extending out of the bearing plane, the adjustable section being electrically connected to the chuck body and configured to have an extended state and a retracted state under pressure from the wafer being inspected; and multiple insulating pillars made of insulating material protruding from the bearing plane, configured to support the wafer being inspected when the adjustable conductive pins are in the retracted state, thereby maintaining the wafer at a set height relative to the bearing plane during inspection. This invention's electron beam inspection device eliminates the dependence on wafer material for electrostatic wafer adsorption, can stabilize high-resistivity, high-dielectric substrate wafers, and significantly broadens its applicable scenarios.

Description

Technical Field

[0001] This invention relates to semiconductor testing equipment, and more particularly to an electron beam testing device. Background Technology

[0002] With the development of semiconductor manufacturing processes, wafer substrates have broken through the limitations of traditional silicon-based materials, expanding to diverse types such as silicon carbide, gallium nitride, glass substrates, and compound semiconductors. This has placed new demands on the resolution, accuracy, and process adaptability of chip defect detection. Electron beam inspection equipment is a key device in the semiconductor manufacturing process for detecting chip performance and defects. Leveraging its ultra-high resolution, it has overcome the diffraction limit of optical inspection, becoming a crucial tool for identifying nanoscale defects and measuring critical dimensions in advanced process chips.

[0003] Electron beam testing works by using an electron gun to fire a focused high-energy electron beam that bombards the surface of the wafer under test. The generated secondary electrons and backscattered electrons are collected and converted into a detection image, thus enabling defect identification and performance testing. The landing energy control precision during electron beam bombardment of the sample surface and the uniformity of the electric field on the wafer surface are the core indicators determining image quality and detection accuracy. The stable achievement of these indicators depends entirely on the wafer chuck providing reliable support and a uniform and controllable bias electric field environment for the wafer.

[0004] However, the diverse types of substrates place higher demands on the die-bonding capabilities of wafer chucks. Existing wafer carrier chucks mostly use electrostatic chucks, vacuum adsorption, or mechanical clamping to fix wafers. Among these, vacuum adsorption solutions are prone to insufficient adsorption force, wafer warping, or even fragmentation when used with non-traditional silicon-based substrates such as porous substrates, thin wafers, and compound semiconductor wafers. The adsorption force of electrostatic chucks is greatly affected by the dielectric constant and resistivity of the wafer substrate, and the adsorption stability of wafers made of different materials varies significantly, making it impossible to achieve compatible fixation of wafers with diverse substrates. Mechanical clamping solutions are prone to edge chipping and structural damage to wafers, and cannot meet the damage-free fixation requirements of advanced process ultra-thin wafers.

[0005] On the other hand, existing chucks generally suffer from poor contact between the wafer and the bias electrode, as well as uneven potential conduction. This is especially true for diverse wafers with different warpages and varying electrical properties of the substrate, which can easily lead to uneven potential distribution on the wafer surface, forming a non-uniform electron beam deceleration electric field. This directly causes the electron beam landing energy to deviate from the process setting value, resulting in image defocusing, missed defects, and false detections. It cannot meet the stringent requirements of advanced process electron beam inspection for electric field stability. Summary of the Invention

[0006] One object of the present invention is to provide an electron beam inspection device for wafer-carrying mechanical chucks that is compatible with wafers on different types of substrates.

[0007] A further objective of this invention is to ensure that the potential of the wafer under test is uniform and stable, thus meeting the stringent requirements of electron beam detection for the electric field environment.

[0008] Another further objective of this invention is to simplify the chuck structure and reduce the maintenance difficulty of electron beam detection equipment.

[0009] Specifically, the present invention provides an electron beam inspection device equipped with a wafer-carrying mechanical chuck. The wafer-carrying mechanical chuck includes: The chuck body is made of conductive material, and a bearing surface is formed on its top. Multiple adjustable conductive pins are disposed on the chuck body, and each adjustable conductive pin has an adjustable section that extends out of the bearing plane. The adjustable section is electrically connected to the chuck body and is configured to have an extended state and a retracted state that is retracted under the pressure of the wafer being tested. Multiple insulating pillars, made of insulating material, protrude from the bearing plane and are configured to support the wafer under test when the adjustable conductive pin is in the retracted state, so that the wafer under test maintains a position at a set height relative to the bearing plane during the testing process.

[0010] Optionally, the height of each insulating post protruding from the bearing plane ranges from 0.05 mm to 0.2 mm, and the resistivity is greater than 10. 15 Ω·mm, hardness greater than Shore D70; The chuck body has mounting holes for fixing insulating posts, and each insulating post is set in the mounting hole with an interference fit.

[0011] Optionally, the static friction coefficient of each insulating post in contact with the back of the wafer under test is greater than 4, and the position of the wafer under test is maintained by the friction generated by the weight of the wafer itself during the test.

[0012] Optionally, the above-mentioned electron beam detection equipment further includes: The electric field power supply is connected to the chuck body and configured to output the rated process voltage, with the rated process voltage ranging from 15kV to 30kV.

[0013] Optionally, the above-mentioned electron beam detection equipment further includes: An insulating ceramic plate is placed below the chuck body for mounting the chuck body. A motion platform, equipped with an insulating ceramic plate, is used to control the movement of the insulating ceramic plate.

[0014] Optionally, the chuck body serves as the anode plate, and the electron beam detection device also includes: The cathode plate is positioned opposite to the chuck body. An electron gun, mounted on a cathode plate, is configured to emit detection electrons toward the wafer under test. An image acquisition device forms a detection image based on the signal excited by detection electrons on the wafer under test; The ranging device is configured to measure the distance from the cathode plate to the wafer being measured.

[0015] Optionally, the above-mentioned electron beam detection equipment further includes: The height adjustment device is configured to acquire the set process potential value of the wafer under test and determine the target distance from the cathode plate to the wafer under test corresponding to the set process potential value; according to the measured distance of the distance measuring device, the motion platform is controlled to move the wafer under test so that the distance from the cathode plate to the upper surface of the wafer under test reaches the target distance, so as to coarsely adjust the height of the wafer under test.

[0016] Optionally, the formula relating the set process potential value of the wafer under test to the target distance is: , In this formula, ΔU i To set the change in process potential, U0 is the rated process voltage, δ is the distance from the wafer under test to the bearing plane, d is the distance from the cathode plate to the upper surface of the wafer under test, Δd is the displacement value from the cathode plate to the upper surface of the wafer under test, h is the thickness of the wafer under test, and ε is the dielectric constant of the detection environment of the electron beam detection equipment.

[0017] Optionally, the above-mentioned electron beam detection equipment further includes: An image quality analysis device is configured to quantify the image quality of a detected image and obtain an image quality score; and The height adjustment device is also configured to verify the coarse adjustment results of the height of the wafer under test based on the image quality score.

[0018] Optionally, the height adjustment device is also configured to: when the image quality score is lower than a preset score threshold, determine that the coarse adjustment result is unqualified, and control the motion platform to drive the wafer under test for fine adjustment until the image quality score reaches or exceeds the preset score threshold.

[0019] The electron beam inspection device of this invention features an adjustable conductive pin that can adapt to wafers of different thicknesses and substrate types. It maintains reliable electrical contact with the wafer during pressure retraction, ensuring reliable electrical conduction between the wafer and the chuck body. The insulating pillar supports the wafer under test when the adjustable conductive pin is in the retracted state, maintaining the wafer at a set height relative to the bearing plane during inspection. This eliminates the dependence on wafer material for electrostatic wafer adsorption and can stably support high-resistivity, high-dielectric substrate wafers such as low-resistivity silicon-based, gallium arsenide (GaAs), lithium niobate (LiNbO3), and glass substrates. This effectively solves the problem of existing chucks being unable to accommodate high-resistivity, high-dielectric wafers, significantly expanding the applicable scenarios of electron beam inspection devices. Furthermore, the electron beam inspection device of this invention strictly limits the physical properties of the insulating pillar. Sufficient static friction is generated through the contact surface with a high static friction coefficient by the wafer's own weight, effectively limiting the horizontal displacement of the wafer during inspection. Stable wafer fixation can be achieved without additional adsorption or clamping structures.

[0020] Furthermore, the electron beam inspection device of the present invention incorporates an insulating ceramic plate beneath the chuck body, achieving reliable electrical isolation between the high-voltage chuck body and the motion platform. This effectively prevents high-voltage leakage and ensures the stability of the chuck body's bias voltage. The motion platform, equipped with the insulating ceramic plate and the chuck body, can precisely move the wafer, meeting the scanning and inspection requirements of the entire wafer surface. For high-resistivity, high-dielectric substrate wafers, the solution of the present invention can determine the target distance from the corresponding cathode plate to the wafer based on the set process potential value of the wafer under test, enabling closed-loop control. This allows for precise adjustment of the wafer surface potential, ensuring uniformity and stability of the potential distribution, meeting the requirements of electron beam inspection for the electric field environment, and significantly improving inspection accuracy and reliability.

[0021] Furthermore, the electron beam detection device of the present invention has a simple mechanical chuck main structure, without complex electrostatic adsorption and electrode arrangement, and the manufacturing cost is lower than that of traditional electrostatic chucks. It avoids the connection of internal and external components of the vacuum cavity, and does not require separate diagnosis of internal and external components during fault diagnosis, which greatly reduces the difficulty and cost of maintenance and improves the economy and operation and maintenance efficiency of the equipment.

[0022] The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0023] The following sections will describe some specific embodiments of the invention in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings: Figure 1This is a schematic diagram of a wafer-carrying mechanical chuck in an electron beam inspection device according to an embodiment of the present invention; Figure 2 yes Figure 1 The diagram shows the structure of the insulating pillar and the chuck body in the wafer carrier mechanical chuck. Figure 3 This is a schematic diagram of the working state of an electron beam detection device according to an embodiment of the present invention; Figure 4 This is a schematic block diagram of a control component in an electron beam detection device according to an embodiment of the present invention. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0025] Figure 1 This is a schematic diagram of a wafer-carrying mechanical chuck in an electron beam inspection device according to an embodiment of the present invention. Figure 2 yes Figure 1 The diagram shows the structural connection between the insulating post 12 and the chuck body 10 in a wafer carrier mechanical chuck. The wafer carrier mechanical chuck is used to carry the wafer 30 under test for various testing processes. It is arranged within the testing process chamber of an electron beam inspection device, and the testing environment is generally a high vacuum environment. A wafer carrier mechanical chuck generally includes: a chuck body 10, multiple adjustable conductive pins 11, and multiple insulating posts 12.

[0026] The chuck body 10 is made of a conductive material, and a bearing surface 101 is formed on its top. In some embodiments, the chuck body 10 is formed from a highly conductive, non-outgassing conductive material such as non-magnetic stainless steel or titanium alloy, and the whole can be a disk-shaped structure that matches the size of the wafer 30 being measured, with a flat bearing surface 101 formed on its top that meets the flatness requirements. The bearing surface 101 is generally arranged along a horizontal plane.

[0027] Multiple adjustable conductive pins 11 are disposed on the chuck body 10, and each adjustable conductive pin 11 has an adjustable section extending out of the bearing plane 101. The adjustable section is electrically connected to the chuck body 10 and configured to have an extended state and a retracted state when subjected to pressure from the wafer 30 being tested. The multiple adjustable conductive pins 11 can be evenly arranged on the bearing plane 101 of the chuck body 10. The number and arrangement of the adjustable conductive pins 11 can be set according to the specifications of the wafer 30 being tested.

[0028] Each adjustable conductive pin 11 can be a spring-loaded conductive pin structure, such as including a pin sleeve, a spring, and a pin shaft (the components of the adjustable conductive pin 11 are not shown in the figure). The pin sleeve is fixedly embedded in the mounting hole of the chuck body 10, maintaining a reliable electrical connection with the chuck body 10. The exposed section of the pin shaft is an adjustable section extending out of the bearing plane 101, and the spring is disposed inside the pin sleeve to provide a continuous axial preload force to the pin shaft. The elastic modulus of the adjustable conductive pin 11 requires that the adjustable conductive pin 11 be compressed to a retracted state when subjected to the gravity of the wafer 30 being tested, but still able to maintain reliable contact with the wafer 30 being tested.

[0029] The adjustable conductive pin 11 is configured with two working states: First, the extended state, where, when no wafer 30 is being tested, the adjustable section pops outward, making its height extending from the bearing plane 101 greater than the protrusion height of the insulating post 12; second, the retracted state, where, after the wafer 30 is placed, its own gravity compresses the spring, causing the adjustable section to retract inward. At this time, the preload of the adjustable conductive pin 11 ensures that the tip of the adjustable section remains in close contact with the back surface of the wafer 30. Each adjustable conductive pin 11 can independently and adaptively extend and retract. The adjustable conductive pin 11 can adapt to wafers of different thicknesses and substrate types, maintaining reliable electrical contact with the wafer during the pressure retraction process, thus achieving reliable electrical conduction between the wafer and the chuck body 10.

[0030] Multiple insulating posts 12, made of insulating material, protrude from the bearing plane 101 and are configured to support the wafer 30 under test when the adjustable conductive pin 11 is in the retracted state, thus maintaining the wafer 30 at a set height relative to the bearing plane 101 during the inspection process. The multiple insulating posts 12 and the adjustable conductive pin 11 are arranged alternately, protruding from the bearing plane 101 of the chuck body 10, and are used to stably support the wafer 30 under test when the adjustable conductive pin 11 is in the retracted state. By supporting the wafer 30 under test when the adjustable conductive pin 11 is in the retracted state, the insulating posts 12 eliminate the dependence on wafer material when using electrostatic wafer adsorption, and can stably support high-resistivity, high-dielectric substrate wafers. This effectively solves the problem that existing chucks cannot adapt to high-resistivity, high-dielectric wafers, significantly expanding the applicable scenarios of electron beam inspection equipment.

[0031] The height of each insulating post 12 protruding from the bearing plane 101 ranges from 0.05 mm to 0.2 mm, and the resistivity is greater than 10. 15 Ω·mm, hardness greater than Shore D70; the chuck body 10 has mounting holes for fixing insulating posts 12, and each insulating post 12 is set in the mounting hole by interference fit.

[0032] The height of the insulating post 12 is the set gap between the wafer 30 being measured and the supporting plane 101, and can be precisely customized according to process requirements. The insulating post 12 is made of a high-resistance insulating polymer material with low vacuum outgassing rate. For example, the material can include, but is not limited to, modified polyetheretherketone (PEEK), high-purity alumina ceramic, and polyimide. It is required to be undeformed under wafer gravity load and high vacuum environment to ensure that the height of each support point of the wafer is consistent, while avoiding leakage and partial discharge under high voltage.

[0033] The bearing surface 101 of the chuck body 10 has mounting holes that correspond one-to-one with the insulating posts 12. The lower end of each insulating post 12 can be provided with a mounting structure that matches the mounting hole, and it is fixed in the mounting hole by an interference fit, which not only ensures that the installation is firm and without displacement, but also eliminates the risk of high voltage discharge caused by installation gaps.

[0034] The static friction coefficient of the contact area between each insulating post 12 and the back side of the wafer 30 under test is greater than 4. The friction force generated by the weight of the wafer 30 under test maintains the position of the wafer 30 under test during the detection process. In some embodiments, the top area of ​​the insulating post 12 in contact with the back side of the wafer 30 under test can be modified by micro-nano structuring or high-friction vacuum coating to make its static friction coefficient with the back side of the wafer 30 under test greater than 4. The weight of the wafer 30 under test is sufficient to generate sufficient static friction force to limit the horizontal displacement of the wafer during the detection process, and the wafer can be fixed without damage without additional adsorption or clamping structures.

[0035] The electron beam inspection equipment in this embodiment uses mechanical bearing instead of electrostatic adsorption, eliminating the need to rely on dielectrics to generate adsorption force. This fundamentally avoids the problem of wafers being unable to release due to abnormal dielectric performance after prolonged high-voltage processes, reducing the probability of wafer damage. At the same time, it reduces the risk of equipment downtime caused by wafer release failures, ensuring the continuity of the inspection process and the stability of equipment operation.

[0036] Figure 3 This is a schematic diagram of the working state of an electron beam detection device according to an embodiment of the present invention. Figure 4 This is a schematic block diagram of the control components in an electron beam detection device according to an embodiment of the present invention. Because the protrusion height of the insulating post 12 is extremely small relative to the overall size of the chuck body 10, therefore... Figure 3 The insulating post 12, the adjustable conductive needle 11, and the gap between the wafer 30 being tested and the bearing plane 101 are not shown in the diagram.

[0037] The aforementioned electron beam inspection equipment can be further equipped with an electric field power supply 15, an insulating ceramic plate 13, and a motion platform 14. The electric field power supply 15 is connected to the chuck body 10 and configured to output the process rated voltage. The value of the process rated voltage ranges from 15kV to 30kV; for example, the electric field power supply 15 can provide a high voltage of 20kV. The specific value of the process rated voltage can be configured according to the substrate of the wafer 30 being tested and the requirements of the inspection process.

[0038] The electric field power supply 15 can be a high-precision high-voltage DC power supply. Its positive output terminal is electrically connected to the chuck body 10, and its negative terminal is grounded, making the chuck body 10 the anode plate of the deceleration electric field of the electron beam. After the high voltage output from the electric field power supply 15 is applied to the chuck body 10, it is synchronously and uniformly transmitted to the wafer 30 under test through the adjustable conductive pin 11. For low-resistivity, low-dielectric substrate wafers, the adjustable conductive pin 11 contacts the wafer. Due to the high-voltage breakdown effect, the wafer exhibits conductor characteristics, and its surface potential is consistent with the output of the electric field power supply 15 with a fast response. For high-resistivity, high-dielectric substrate wafers, the electric field power supply 15 outputs the process rated voltage. Through closed-loop control of "voltage monitoring - algorithm conversion - displacement adjustment", the surface potential of the wafer can be precisely controlled to ensure the uniformity and stability of the potential distribution of the wafer 30 under test.

[0039] An insulating ceramic plate 13 is disposed below the chuck body 10 for mounting the chuck body 10. In some embodiments, the insulating ceramic plate 13 may be made of high-purity alumina insulating ceramic material, and the chuck body 10 is fixed to the upper surface of the insulating ceramic plate 13. The lower surface of the insulating ceramic plate 13 is fixedly mounted on the moving part of the motion platform 14. The insulating ceramic plate 13 is used to achieve reliable electrical isolation between the high-voltage energized chuck body 10 and the motion platform 14, avoiding interference from high-voltage leakage and electrical crosstalk on motion control and detection signals.

[0040] The motion platform 14 is equipped with an insulating ceramic plate 13 for controlled movement of the insulating ceramic plate 13. In some embodiments, the motion platform 14 may employ a wedge-shaped structure to convert horizontal movement into vertical displacement. For example, the motor of the motion platform 14 drives the driving block to move horizontally, and the inclined linear guide rails of the driving block and the driven block cooperate with each other. The horizontal movement of the driving block drives the driven component to complete the vertical displacement through inclined surface compression. The motion platform 14 provides a precise motion basis for wafer inspection and focus adjustment through height adjustment.

[0041] The control components of the electron beam detection equipment may include: an image acquisition device 213, a ranging device 22, a height adjustment device 211, and an image quality analysis device 214.

[0042] The cathode plate 20 of the electron beam detection device is positioned opposite to the chuck body 10. The chuck body 10 serves as the anode plate, thus forming a pair of oppositely positioned electrodes. The electron gun 21 is mounted on the cathode plate 20 and configured to emit detection electrons into the wafer 30 under test. The cathode plate 20 and the cathode emitter of the electron gun 21 are at the same potential and connected to the reference ground potential, forming a stable electric field between them and the chuck body 10, which is connected to a positive high voltage. This field is used to regulate the acceleration and deceleration process of the electron beam and precisely control the landing energy of the electron beam.

[0043] The image acquisition device 213 is configured to form a detection image based on the signal excited by the detection electrons on the wafer 30 under test. The image acquisition device 213 can collect the secondary electron signal excited when the detection electron beam bombards the surface of the wafer 30 under test, amplify the weak electrical signal and convert it into a digital signal to generate a grayscale detection image of the corresponding wafer surface morphology.

[0044] The ranging device 22 is fixedly mounted on the cathode plate 20 (upper plate) and configured to measure the distance from the cathode plate 20 to the wafer 30 being measured. In some embodiments, the measuring optical axis of the ranging device 22 is parallel to the optical axis of the electron gun 21, and is configured to measure the vertical distance from the reference surface of the cathode plate 20 to the upper surface of the wafer 30 being measured in real time. The measurement data is transmitted to the height adjustment device 211 in real time, providing an accurate basis for wafer height adjustment.

[0045] The height adjustment device 211 is configured to: acquire the set process potential value of the wafer 30 under test, and determine the target distance from the cathode plate 20 to the wafer 30 under test corresponding to the set process potential value; control the motion platform 14 to move the wafer 30 under test according to the measured distance of the ranging device 22, so that the distance from the cathode plate 20 to the upper surface of the wafer 30 under test reaches the target distance, so as to coarsely adjust the height of the wafer 30 under test. The input terminal of the height adjustment device 211 is connected to the ranging device 22, the electric field power supply 15, and the image quality analysis device 214 respectively, and the output terminal is connected to the control terminal of the motion platform 14. According to the real-time measurement data of the ranging device 22, the motion platform 14 is controlled to complete the coarse adjustment of the wafer height, and at the same time, the coarse adjustment verification and closed-loop fine adjustment are completed according to the image quality score.

[0046] During the testing process, the electric field power supply 15 continuously outputs a high DC voltage, and the height adjustment device 211 regulates the wafer surface voltage according to the relative positional relationship between the chuck body 10 and the upper electrode plate (cathode plate 20). The underlying principle of the height adjustment being related to the set process potential value of the wafer 30 under test is as follows.

[0047] In the initial state of the DC high voltage output by the electric field power supply 15, the tested wafer 30 is rapidly polarized while the free charges do not respond. The residual electric field after polarization inside the tested wafer 30 is expressed as: ε0E' = ε0E, where ε0 is the dielectric constant of the wafer, ε is the dielectric constant of the detection environment (vacuum environment), E and E' are the residual electric field strength of the wafer and the electric field strength of the detection environment, respectively.

[0048] The electric field path integral yields: E(dh) + E'h = U0, where U0 is the process rated voltage output by the electric field power supply 15, d is the distance from the cathode plate 20 to the upper surface of the wafer 30 under test, and h is the thickness of the wafer 30 under test. The potential at the upper surface of the wafer 30 under test is then: U i =E(dh-δ)=U0(dh-δ) / (dh(1-1 / ε)), where δ is the distance from the measured wafer 30 to the bearing plane 101.

[0049] The final electric state (stable state under the influence of the electric field) of the tested wafer 30 is when the surface density of free charges inside the tested wafer 30 reaches a stable state. At this point, there are no polarization charges, and the electric field strength inside the tested wafer 30 is zero after stabilization. Therefore, the path integral of the electric field is: E(dh) = U0. Hence, E = U0 / (dh). The surface potential of the tested wafer 30 is expressed as: U f =E(dh-δ)=U0(dh-δ) / (dh).

[0050] Based on the above formula, the formula relating the set process potential value of the tested wafer 30 to the target distance is derived as follows: , In this formula, ΔU i To set the change in process potential, U0 is the rated process voltage, δ is the distance from the tested wafer 30 to the bearing plane 101, d is the distance from the cathode plate 20 to the upper surface of the tested wafer 30, Δd is the displacement value from the cathode plate 20 to the upper surface of the tested wafer 30, h is the thickness of the tested wafer 30, and ε is the dielectric constant of the detection environment of the electron beam detection equipment.

[0051] Image quality analysis device 214 can be configured to quantify the image quality of the detected image to obtain an image quality score. Height adjustment device 211 is also configured to verify the coarse adjustment result of the height of the tested wafer 30 based on the image quality score. Image quality analysis device 214 incorporates an image quality quantization scoring algorithm, configured to perform multi-dimensional feature extraction and quantization processing on the received detected image, and output an image quality score. In some embodiments, the core dimensions of the scoring algorithm include image edge gradient, image contrast, high-frequency energy ratio in the frequency domain, signal-to-noise ratio, and wafer standard pattern matching degree. A higher score indicates better detected image quality, better focus state, and better electric field uniformity. In some embodiments, the numerical range of the image quality score is 0-100. Since the image quality quantization scoring algorithm itself is well known to those skilled in the art, it will not be described in detail here. In this embodiment, the inventors creatively apply the image quality score to the height adjustment of the motion platform 14.

[0052] If the image quality score is lower than the preset score threshold, the height adjustment device 211 is also configured to determine that the coarse adjustment result is unqualified, and control the motion platform 14 to drive the wafer 30 under test to perform fine adjustment until the image quality score reaches or exceeds the preset score threshold.

[0053] The image quality analysis device 214 can quantify the quality of the detected image to obtain an image quality score that intuitively reflects the imaging focus state and electric field stability, which serves as the verification basis for the coarse adjustment results. This image quality score-based verification method can directly correlate with the core imaging effect of electron beam detection, avoiding errors caused by judging the adjustment effect solely based on distance data. It can effectively identify problems caused by electric field distortion, wafer warping, etc., where the distance meets the requirements but the image is out of focus, ensuring the validity of the coarse adjustment results and providing a clear judgment basis for subsequent fine-tuning.

[0054] The height adjustment device 211 has a preset score threshold. For example, in this embodiment, the preset score threshold can be set to 90 points when the image quality score is out of 100, corresponding to the ideal imaging state with the clearest focus and the most stable electric field. When the image quality score is lower than the preset score threshold, the height adjustment device 211 determines that the coarse adjustment result is unqualified and controls the motion platform 14 to drive the tested wafer 30 to perform fine adjustment along the Z-axis, synchronously acquiring the quality score of the detected image in real time, until the score reaches or exceeds the preset score threshold, at which point the adjustment stops immediately, completing the closed-loop control. Based on the closed-loop fine adjustment design of the image quality score, the height adjustment device 211 realizes precise closed-loop control of the wafer height, which can adaptively match the electric field changes and focal length shifts of different substrate wafers and different detection areas, adapt to different processes of the electron gun 21, and improve the adaptability to diverse wafers and full wafer surface inspection.

[0055] The above adjustment process, through the closed-loop coordination of the high voltage output of the electric field power supply 15 with the height adjustment device 211 and the distance measuring device 22, can dynamically adjust the high voltage output and chuck position according to the characteristics of different substrate wafers, so as to achieve precise matching of process parameters. This not only improves the intelligence level of the detection process, but also flexibly adapts to the detection needs of wafers of different specifications and materials, and enhances the versatility and process adaptability of the equipment.

[0056] A specific adjustment process of the height adjustment device 211 can be as follows: After the wafer 30 under test is reliably placed behind the insulating pillar 12, the electric field power supply 15 applies a 20kV high voltage to the chuck body 10. Due to the high-resistivity, high-dielectric substrate of the wafer 30 under test, an electron beam deceleration electric field is formed on its surface under the influence of the electric field. The process setting in the electron gun 21 is 15kV. If the target distance corresponds to the 15kV high voltage, when the wafer 30 under test is moved to other areas, the monitoring voltage of the electron gun 21 will change relatively due to the non-uniform electric field, and its image quality will be out of focus (image quality scoring system score less than or equal to 90 points). The adjustment target is to adjust the height of the motion stage until the image in the center area of ​​the wafer is clear (image quality scoring system score greater than 90 points). The difference ΔU between the monitoring voltage at this position and the process setting voltage is input to the height adjustment algorithm, and the algorithm calculates and determines the coarse adjustment stroke of the motion platform 14. If the image quality score is greater than 90 after the coarse adjustment is completed, the adjustment distance is deemed acceptable; if the image quality score is less than or equal to 90, a signal is sent to the motion platform 14 to readjust the distance based on the real-time difference until the score is greater than 90, at which point the adjustment is complete.

[0057] Therefore, those skilled in the art should recognize that although numerous exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Thus, the scope of the present invention should be understood and construed as covering all such other variations or modifications.

Claims

1. An electron beam inspection device, comprising a wafer-carrying mechanical chuck, the wafer-carrying mechanical chuck comprising: The chuck body is made of conductive material, and a bearing surface is formed on its top. Multiple adjustable conductive pins are disposed on the chuck body, and each of the adjustable conductive pins has an adjustable section extending out of the bearing plane. The adjustable section is electrically connected to the chuck body and configured to have an extended state and a retracted state when subjected to the pressure of the wafer being tested. Multiple insulating pillars, made of insulating material, protrude from the bearing plane and are configured to support the wafer under test when the adjustable conductive pin is in the retracted state, so that the wafer under test maintains a position at a set height relative to the bearing plane during the testing process.

2. The electron beam detection device according to claim 1, wherein... The height of each insulating post protruding from the bearing plane ranges from 0.05 mm to 0.2 mm, and the resistivity is greater than 10. 15 Ω·mm, hardness greater than Shore D70; The chuck body has mounting holes for fixing the insulating posts, and each insulating post is set in the mounting hole by an interference fit.

3. The electron beam detection device according to claim 2, wherein... The static friction coefficient of the contact area between each insulating post and the back of the wafer under test is greater than 4, and the position of the wafer under test is maintained by the friction generated by the weight of the wafer itself during the detection process.

4. The electron beam detection apparatus according to any one of claims 1 to 3, further comprising: An electric field power supply is connected to the chuck body and configured to output the process rated voltage, the value of which ranges from 15kV to 30kV.

5. The electron beam detection device according to claim 4, further comprising: An insulating ceramic plate is disposed below the chuck body for mounting the chuck body; A motion platform, equipped with the insulating ceramic plate, is used to controllably move the insulating ceramic plate.

6. The electron beam detection device according to claim 5, wherein, The chuck body serves as the anode plate, and the electron beam detection device further includes: The cathode plate is disposed opposite to the chuck body; An electron gun, disposed on the cathode plate, is configured to emit detection electrons toward the wafer under test; An image acquisition device is configured to form a detection image based on the signal excited on the wafer under test by the detection electrons; A ranging device configured to measure the distance from the cathode plate to the wafer under test.

7. The electron beam detection device according to claim 6, further comprising: The height adjustment device is configured to acquire a set process potential value of the wafer under test and determine a target distance from the cathode plate to the wafer under test corresponding to the set process potential value; and control the motion platform to move the wafer under test according to the distance measured by the distance measuring device, so that the distance from the cathode plate to the upper surface of the wafer under test reaches the target distance, so as to coarsely adjust the height of the wafer under test.

8. The electron beam detection device according to claim 7, wherein, The formula relating the set process potential value of the wafer under test to the target distance is as follows: ， In this formula, ΔU i The change in the set process potential value is defined as follows: U0 is the rated process voltage; δ is the distance from the wafer under test to the bearing plane; d is the distance from the cathode plate to the upper surface of the wafer under test; Δd is the displacement value from the cathode plate to the upper surface of the wafer under test; h is the thickness of the wafer under test; and ε is the dielectric constant of the detection environment of the electron beam detection equipment.

9. The electron beam detection device according to claim 7, further comprising: An image quality analysis device is configured to quantify the image quality of the detected image and obtain an image quality score. and The height adjustment device is also configured to verify the coarse adjustment result of the height of the wafer under test based on the image quality score.

10. The electron beam detection device according to claim 9, wherein, The height adjustment device is further configured to: when the image quality score is lower than a preset score threshold, determine that the coarse adjustment result is unqualified, and control the motion platform to drive the wafer under test for fine adjustment until the image quality score reaches or exceeds the preset score threshold.

Images