Wafer clamping device and detection system

Abstract

The invention discloses a wafer clamping device which comprises a chuck provided with a plurality of air holes penetrating through the chuck in the axial direction of the chuck, the air holes comprise a plurality of first air holes and a plurality of second air holes, the first air holes form a first pressure area, and the second air holes form a second pressure area. The first pressure area and the second pressure area enable the wafer to suspend above the chuck; the pressure maintaining structure is fixedly connected with the chuck, and the pressure maintaining structure is arranged to be annular and surrounds the peripheries of the multiple air holes; the clamping assembly comprises a connecting part and a clamping part, the connecting part is connected with the chuck, and the clamping part clamps the edge of the wafer; the driving assembly is connected with the chuck and drives the chuck to rotate. The beneficial effects of the invention are that a certain gap is always kept between the wafer and the chuck under the combined action of the pressurization area and the decompression area; meanwhile, the peripheral side of the chuck is provided with a corresponding pressure maintaining structure, so that the air pressure between the wafer and the chuck is kept stable, and the wafer clamping stability is further improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and more particularly, to a wafer clamping device and a detection system. Background Art

[0002] During the process of detecting or processing a wafer, it is necessary to fix the wafer. In order to avoid contaminating the surface of the wafer, a non-contact clamping device is usually selected to fix the wafer, so that the wafer floats above the clamping device.

[0003] However, the current non-contact clamping device has poor stability, which will have an adverse impact on the processing or detection quality of the wafer, and even cause the wafer to break. Summary of the Invention

[0004] To solve the above problems, an object of the present invention is to provide a wafer clamping device and a detection system.

[0005] On the one hand, the present invention provides a wafer clamping device, which includes:

[0006] A chuck having a plurality of air holes axially penetrating the chuck. The plurality of air holes include a plurality of first air holes and a plurality of second air holes. The plurality of first air holes form a first pressure area, and the plurality of second air holes form a second pressure area. The first pressure area and the second pressure area suspend the wafer above the chuck;

[0007] A pressure maintaining structure fixedly connected to the chuck. The pressure maintaining structure is arranged in a ring shape and surrounds the outer periphery of the plurality of air holes;

[0008] A clamping assembly including a connecting portion and a clamping portion. The connecting portion is connected to the chuck, and the clamping portion clamps the edge of the wafer;

[0009] A driving assembly connected to the chuck and driving the chuck to rotate.

[0010] As a further improvement of the present invention, the first air hole is an air outlet hole, and the first pressure area is a pressurized area; and / or

[0011] The second air hole is an air suction hole, and the second pressure area is a decompression area.

[0012] As a further improvement of the present invention, the air outlet hole satisfies:

[0013] Q = n / 100 + 4.2

[0014] Wherein, Q is the gas flow rate of the air outlet hole, in units of L / min, and n is the rotation speed of the chuck, in units of rpm.

[0015] As a further improvement of the present invention, a plurality of the air holes are arranged radially starting from the center of the chuck; or

[0016] A plurality of the air holes are arranged concentrically with the center of the chuck as the center.

[0017] As a further improvement of the present invention, the first pressure area and the second pressure area are arranged intersectingly or spaced apart.

[0018] As a further improvement of the present invention, the pressure maintaining structure is arranged on the circumferential side of the chuck and protrudes from the first surface of the chuck, and the first surface is the surface of the chuck facing the wafer.

[0019] As a further improvement of the present invention, a buffer is provided between the pressure maintaining structure and the first surface, and the surface of the buffer facing the wafer is a plane or an arc surface.

[0020] As a further improvement of the present invention, a plurality of the clamping assemblies are provided, and the plurality of the clamping assemblies are evenly arranged along the circumferential direction of the chuck.

[0021] As a further improvement of the present invention, the clamping part is provided with an opening facing the wafer, and the edge part of the wafer is located in the opening;

[0022] The opening includes a first wall body, a second wall body and a third wall body which are connected in sequence, and the second wall body is arranged as a plane or an arc surface; and / or

[0023] The first wall body and / or the third wall body are arranged as stepped surfaces.

[0024] On the other hand, the present invention also provides a detection system, and the detection system includes the wafer clamping device as described above.

[0025] The beneficial effects of the present invention are as follows: By optimizing the setting manner of the air holes on the chuck, a pressurized area and a decompressed area are formed on the surface of the chuck, so that the wafer always maintains a certain gap with the chuck under the combined action of the pressurized area and the decompressed area; meanwhile, a corresponding pressure maintaining structure is arranged on the circumferential side of the chuck, so that the air pressure between the wafer and the chuck is kept stable, and the stability of clamping the wafer is further improved. Description of the Drawings

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings according to these drawings without creative efforts.

[0027] Figure 1 Schematic structural diagram of an exemplary wafer clamping device;

[0028] Figure 2 is Figure 1 Schematic structural diagram of the middle air hole arrangement;

[0029] Figure 3a Schematic structural diagram of an exemplary buffer;

[0030] Figure 3b Schematic structural diagram of another exemplary buffer;

[0031] Figure 4a Schematic structural diagram of an exemplary clamping part;

[0032] Figure 4b Schematic structural diagram of another exemplary clamping part;

[0033] Figure 4c Schematic structural diagram of another exemplary clamping part;

[0034] Figure 4d Schematic structural diagram of another exemplary clamping part;

[0035] Figure 5a Schematic structural diagram of an exemplary air hole arrangement;

[0036] Figure 5b Schematic structural diagram of another exemplary air hole arrangement;

[0037] Figure 6 is Figure 5b Simulation diagram of the airflow stability corresponding to the shown air hole distribution;

[0038] Figure 7 Graph of wafer fluctuations with and without a pressure maintaining structure.

[0039] In the figure,

[0040] 10. Chuck; 11. Air hole; 111. First air hole; 112. Second air hole; 20. Pressure maintaining structure; 30. Clamping assembly; 31. Clamping part; 32. Connecting part; 33. Opening; 331. First wall body; 332. Second wall body; 333. Third wall body; 40. Driving assembly; 50. Wafer; 60. Flange; 70. Rotating shaft; 80. Buffer; 90. Gap. Detailed implementation manners

[0041] It is known that during the processing of wafers such as etching, or during the inspection of wafers such as edge detection, or during the measurement of wafers, the wafers need to be rotated. The wafer clamping device will drive the wafer to rotate synchronously under the drive of the rotation drive unit.

[0042] In the prior art, in order to avoid contaminating the surface of the wafer, a non-contact clamping method is usually selected to clamp and fix the wafer. The non-contact clamping device is based on the Bernoulli principle, providing an air flow between the chuck and the wafer, and suspending the wafer above the chuck by controlling the speed of the air flow.

[0043] However, during the rotation of the wafer, there are usually situations where the air flow is unstable or the air flow distribution is uneven, resulting in the wafer fluctuating up and down during rotation, which not only affects the normal detection or processing quality of the wafer; if the fluctuation amplitude of the wafer is large, it will cause friction or collision between the wafer and the chuck, leading to the problem of wafer fragmentation.

[0044] Especially when the wafer is rotating at a high speed above 1000 rpm, due to the lack of a pressure maintaining structure in the chuck, the air pressure between the chuck and the wafer will decrease rapidly, that is, the air flow rate between the chuck and the wafer will decrease rapidly, and the adsorption force of the chuck on the wafer will weaken. Under the action of rotation, the wafer will slide circumferentially along the chuck, eventually resulting in wafer fragmentation.

[0045] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0046] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present invention, the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0047] In addition, in the description of the present invention, the terms used are for illustrative purposes only and are not intended to limit the scope of the present invention. The terms "comprising" and / or "including" are used to specify the presence of the elements, steps, operations, and / or components described, but do not exclude the presence or addition of one or more other elements, steps, operations, and / or components. The terms "first", "second", etc. may be used to describe various elements, do not represent an order, and do not limit these elements. In addition, in the description of the present invention, unless otherwise specified, "a plurality of" means two or more. These terms are only used to distinguish one element from another. In conjunction with the following drawings, these and / or other aspects become apparent, and it is easier for those of ordinary skill in the art to understand the description of the embodiments of the present invention. The drawings are only used to depict the embodiments of the present invention for illustrative purposes. Those skilled in the art will easily recognize from the following description that alternative embodiments of the structure and method shown in the present invention can be adopted without departing from the principles described in the present invention.

[0048] For ease of understanding, in the drawings of this application, the X-axis is the length direction of the wafer chucking device, that is, the radial direction of the wafer; that is, the radial direction of the air holes; the Y-axis is the height direction of the wafer chucking device, that is, the axial direction of the wafer; that is, the axial direction of the air holes.

[0049] Take Figure 1 as an example to illustrate the structure of a wafer chucking device according to an embodiment of the present invention: The wafer chucking device includes a chuck 10, a pressure maintaining structure 20, a clamping assembly 30, a driving assembly 40, a flange 60, and a rotating shaft 70. Under the combined action of the chuck 10 and the clamping assembly 30, the wafer 50 is stably located above the chuck 10. Among them:

[0050] The chuck 10 is provided with a plurality of air holes 11 penetrating through the chuck 10 along its axial direction. That is to say, the plurality of air holes 11 penetrate through the chuck 10 from top to bottom along the Y-axis direction (the height direction of the wafer chucking device), so that gas flow can be realized through the plurality of air holes 11.

[0051] As Figure 2 shown, the plurality of air holes 11 include a plurality of first air holes 111 and a plurality of second air holes 112. The plurality of first air holes 111 form a first pressure zone, and the plurality of second air holes 112 form a second pressure zone. The first pressure zone and the second pressure zone suspend the wafer 50 above the chuck 10, so that a gap 90 is always maintained between the chuck 10 and the wafer 50.

[0052] It can be understood that multiple air holes 11 can communicate with an external air pump (not shown in the figure). For example, the first air hole 111 communicates with the external first air pump, and air flow is delivered to the first air hole 111 through the first air pump, that is, air is inflated into the gap 90 through multiple first air holes 111, and then a first pressure area is formed in the gap 90. Under the action of the inflated air flow in the first pressure area, the wafer 50 will be "lifted" to make it away from the chuck 10; the second air hole 112 communicates with the external second air pump, and the air flow is pumped away from the second air hole 112 through the second air pump, that is, air is pumped out of the gap 90 through multiple second air holes 112, and then a second pressure area is formed in the gap 90. Under the action of the air suction flow in the second pressure area, the wafer 50 will be "adsorbed" to make it close to the chuck 10.

[0053] It is easy to understand that the pressure in the first pressure area is greater than the pressure in the second pressure area. Under the combined action of the air flow pressures in the first pressure area and the second pressure area, the wafer 50 is balanced in force and stably located above the chuck 10 without contacting the chuck 10. Thus, friction or collision between the wafer 50 and the chuck 10 can be avoided, ultimately ensuring the safety of the wafer 50 during clamping, processing or detection, and avoiding its up and down fluctuations affecting the detection quality or causing fragmentation due to unstable air flow or unbalanced force.

[0054] It should be noted that the above description of the first air hole 111 delivering air flow, that is, the first air hole is an air outlet hole and the first pressure area is a high-pressure area (or pressurized area); the second air hole 112 pumping away air flow, that is, the second air hole 112 is an air suction hole and the second pressure area is a low-pressure area (or decompression area) is only an exemplary description of this application. In use, the first air hole 111 can also be set as an air suction hole and the first pressure area can be set as a low-pressure area according to needs; the second air hole 112 can be set as an air outlet hole and the second pressure area can be set as a high-pressure area. As long as the wafer 50 can be stably suspended above the chuck 10, this application does not make specific limitations on it.

[0055] Furthermore, the air outlet hole satisfies:

[0056] Q = n / 100 + 4.2, where Q is the gas flow rate of the air outlet hole, with the unit of L / min, and n is the rotation speed of the chuck 10, with the unit of rpm.

[0057] It is known that when the wafer 50 rotates at a high speed driven by the chuck 10, the air flow in the gap 90 will more or less be partially "thrown out" due to the rotation effect. When the air flow of the first air hole 111 satisfies the above gas flow rate, even when the wafer 50 rotates at a high speed, it can ensure that there is sufficient air flow in the gap 90 to maintain the suspended state of the wafer 50, thereby avoiding friction or collision between the wafer 50 and the chuck 10 due to insufficient air pressure in the gap 90.

[0058] ForFigure 5a and Figure 5b For example, taking Figure 5b as an example, the setting manner of the air holes 11 on the chuck 10 will be further described:

[0059] For example, multiple air holes 11 are arranged radially starting from the center of the circle of the chuck 10. Taking Figure 5a as an example for illustration: Multiple air holes 11 start from the center of the circle of the chuck 10 and form three radially outward meridians, and the included angle between adjacent meridians is 120°. Among them, the length of each meridian is equal, that is, the number of air holes 11 arranged on each meridian is equal, and multiple air holes 11 are arranged at equal intervals on each meridian. Preferably, the number of air holes 11 on each meridian can be set to an even number. Half of the number of air holes 11 are the first air holes 111, and the other half of the number of air holes 11 are the second air holes 112, and the first air holes 111 and the second air holes 112 are arranged at intervals. Thus, the air flow pressure at each position of the gap 90 can be made the same, and further ensure that the wafer 50 is uniformly stressed at each position, and the wafer 50 can stably float above the chuck 10 without causing the wafer 50 to fluctuate up and down and rub or collide with the chuck 10 due to unstable air flow or uneven stress.

[0060] It is easy to understand that the length of each meridian can be comprehensively determined according to the size and weight of the wafer 50, etc. For example, the length of each meridian is l, and the radius of the chuck 10 is r. The length of each meridian can be set to 0.5r - r. That is to say, the air holes 11 on each meridian can radiate outward from the center of the circle of the chuck 10 by a length of 0.5r, or radiate outward a greater distance (but this distance should be less than r). In use, when the size of the wafer 50 is larger, the length of each meridian can be appropriately increased, that is, the number of air holes 11 can be appropriately increased; when the weight of the wafer 50 is larger, the length of each meridian can be appropriately increased, that is, the number of air holes 11 can be appropriately increased. This application does not make specific limitations on the length of the meridian, that is, the number of air holes 11.

[0061] Optionally, multiple air holes 11 start from the center of the circle of the chuck 10 and form four, five, six, seven, eight or other numbers of meridians to radiate outward, and multiple radially outward meridians are uniformly arranged on the chuck 10 along the circumferential direction of the chuck 10. In use, it can be adaptively selected according to specific situations. This application does not make specific limitations on the number of meridians formed by the air holes 11, as long as the wafer 50 can be uniformly stressed everywhere.

[0062] It should be noted that the first air holes 111 and the second air holes 112 are arranged at intervals on each of the above-mentioned warp lines, that is, one second air hole 112 is arranged between two first air holes 111; or one first air hole 111 is arranged between two second air holes 112, which is the preferred setting method of the air holes 11, and it cannot be a special limitation on the arrangement method of the air holes 11. In use, the air holes 11 can also be set in other ways. For example, two, three, four or more adjacent air holes 11 can be set as the first air holes 111; then two, three, four or more adjacent air holes 11 can be set as the second air holes 112; or all the air holes 11 on one warp line can be set as the first air holes 111, and all the air holes 11 on the two adjacent warp lines can be set as the second air holes 112, that is to say, the first air holes 111 and the second air holes 112 are arranged at intervals with the warp lines formed by their arrangement as the unit.

[0063] After the numbers of the first air holes 111 and the second air holes 112 are determined, the working parameters of the first air pump and the second air pump can be appropriately adjusted according to the numbers of the first air holes 111 and the second air holes 112 to control the gas flow rates of the first air holes 111 and the second air holes 112. For example, when the number of the first air holes 111 is large and the number of the second air holes 112 is small, the first air pump and the second air pump can be controlled to make the gas flow rate of the first air holes 111 slightly less than the gas flow rate of the second air holes 112, so that the wafer 50 maintains a force balance under the combined action of the first pressure area and the second pressure area.

[0064] It can be understood that the numbers of the first air holes 111 and the second air holes 112 and their respective corresponding gas flow rates can be determined according to the gravity of the wafer 50. For example, the sum of the adsorption forces of multiple second air holes 112 on the wafer 50 can be made equal to or slightly greater than the upward "lifting" force of multiple first air holes 111 on the wafer 50, so that the wafer 50 can be in force balance in the Y-axis direction, that is to say, the resultant force of the wafer 50 in its axial direction is approximately equal to zero, so that the wafer 50 can be suspended above the chuck 10.

[0065] Alternatively, the multiple air holes 11 can also be arranged in a concentric circle shape with the center of the chuck 10 as the center. Take Figure 5b as an example to illustrate: The multiple air holes 11 are arranged in a concentric circle shape with the center of the chuck 10 as the center to form multiple circles and expand step by step along the radial direction of the chuck 10. That is, the farther away from the center of the chuck 10, the larger the size of the circle formed by the air holes 11, and the distance between two adjacent concentric circles is equal.

[0066] Preferably, the multiple air holes 11 on each concentric circle are evenly arranged at equal intervals. The first air holes 111 and the second air holes 112 on each concentric circle can be arranged at intervals. Optionally, as described above, for example, one second air hole 112 is arranged between two first air holes 111; or one first air hole 111 is arranged between two second air holes 112; two, three, or four adjacent air holes 11 can be set as the first air holes 111; then two, three, or four adjacent air holes 11 can be set as the second air holes 112. Or all the air holes 11 on one concentric circle are set as the first air holes 111, and all the air holes 11 on the two adjacent concentric circles are set as the second air holes 112, that is, the first air holes 111 and the second air holes 112 are arranged at intervals in units of the concentric circles formed by their arrangement. In this way, the air flow pressure at each position of the gap 90 can be made the same, thereby ensuring that the wafer 50 is evenly stressed at each position, and the wafer 50 can stably float above the chuck 10 without causing the wafer 50 to fluctuate up and down and rub or collide with the chuck 10 due to unstable air flow or uneven stress. In use, it can be adaptively selected according to the situation, and the present application does not make specific limitations on it.

[0067] As Figure 6 shown, it is a simulation diagram of the air flow pressure at each position of the interval 90 when the air holes 11 are arranged in a concentric circle on the chuck 10. It can be seen from the figure that the air pressure values at each position of the gap 90 are maintained at about 8.7 pa, that is, it can not only ensure that the chuck 10 can provide stable air flow at each position, but also ensure that the wafer 50 can be evenly stressed at each position, thereby ensuring that the wafer 50 can stably float on the surface of the chuck 10 without fluctuating up and down due to unstable air flow or tilting and rubbing or colliding with the chuck 10 due to uneven stress at each position.

[0068] It is easy to understand that the arrangement mode of the first air holes 111 and the second air holes 112 determines the arrangement mode of the first pressure area and the second pressure area.

[0069] As described above: when a second air hole 112 is arranged between two first air holes 111, one first air hole 111 forms a first pressure area, and one second air hole 112 forms a second pressure area. Thus, multiple first pressure areas and multiple second pressure areas are formed on the upper surface of the chuck 10, and the first pressure areas and the second pressure areas are arranged at intervals; when two, three, four or the like adjacent air holes 11 are all set as first air holes 111, and then two, three, four or the like adjacent air holes 11 are all set as second air holes 112, two, three, four or the like adjacent first air holes 111 jointly form a first pressure area, and two, three, four or the like adjacent second air holes 112 jointly form a second pressure area. Thus, multiple first pressure areas and multiple second pressure areas are formed on the upper surface of the chuck 10, and the first pressure areas and the second pressure areas are arranged at intervals; when the first air holes 111 and the second air holes 112 are arranged at intervals with the meridians formed by their arrangement as units, or when the first air holes 111 and the second air holes 112 are arranged at intervals with the concentric circles formed by their arrangement as units, the first air holes 111 on one meridian or one concentric circle jointly form a first pressure area, and the second air holes 112 on one meridian or one concentric circle jointly form a second pressure area. Thus, multiple first pressure areas and multiple second pressure areas are formed on the upper surface of the chuck 10, and the first pressure areas and the second pressure areas are arranged at intervals. When the first air holes 111 and the second air holes 112 are arranged in other ways, the corresponding first pressure area and second pressure area can also be analogously used according to the above principle, which will not be elaborated here.

[0070] It should be noted that when the first air holes 111 and the second air holes 112 are arranged radially, and the meridians formed by the arrangement of the first air holes 111 coincide with the diameter of the chuck 10, and the meridians formed by the arrangement of the second air holes 112 coincide with the diameter of the chuck 10, the first pressure area formed by the first air holes 111 and the second pressure area formed by the second air holes 112 are arranged in an intersecting manner. This situation can also ensure that the wafer 50 is uniformly stressed at each position, so that it can stably float above the chuck 10. In use, the arrangement mode of the first pressure area and the second pressure area can be adjusted by adaptively adjusting the setting positions and / or the setting quantities of the first air holes 111 and the second air holes 112, as long as it can ensure that the wafer 50 is evenly stressed under the joint action of the first pressure area and the second pressure area and stably floats above the chuck 10. The present application does not specifically limit the specific setting mode of the first pressure area and the second pressure area.

[0071] Continue to refer to Figure 1, the pressure maintaining structure 20 is fixedly connected to the chuck 10, and the pressure maintaining structure 20 is arranged in a ring shape and surrounds the outer periphery of the plurality of air holes 11. It can be understood that the pressure maintaining structure 20 forms a physical barrier on the outer periphery of the plurality of air holes 11, which can concentrate the air flow in the plurality of air holes 11 inside the pressure maintaining structure 20, that is, the air flow in the air holes 11 is concentrated as much as possible inside the gap 90, thereby improving the stability of the air flow and the controllability of the air flow in the gap 90. Especially when the chuck 10 is rotating at a high speed, the pressure maintaining structure 20 can block the air flow in the gap 90, preventing the air flow in the gap 90 from being "thrown out" along the radial direction of the chuck 10, so that the wafer 50 cannot obtain sufficient air flow support and then come into contact or collision with the chuck 10. On the other hand, the pressure maintaining structure 20 can also block the air flow or particles in the external environment from impacting the wafer 50, forming a certain protective effect on the wafer 50.

[0072] Preferably, the pressure maintaining structure 20 is arranged on the circumferential side of the chuck 10 and protrudes from the first surface of the chuck 10. The first surface is the surface of the chuck 10 facing the wafer 50.

[0073] For example, the first surface of the chuck 10 is the upper surface in its axial direction. The pressure maintaining structure 20 can be understood as a flange arranged on the outer peripheral surface of the chuck 10 and protruding towards the upper surface of the chuck 10. That is, the pressure maintaining structure 20 extends a certain height in the direction away from the upper surface of the chuck 10, so that the pressure maintaining structure 20 is located between the chuck 10 and the wafer 50, that is, the pressure maintaining structure 20 partially closes the gap 90 in the height direction, that is, the height of the pressure maintaining structure 20 in the Y-axis direction is always less than the height of the gap 90 in the Y-axis direction. In this way, on the one hand, it can block the air flow in the gap 90 and improve the stability and controllability of the air flow in the gap 90; on the other hand, the extended height of the pressure maintaining structure 20 can form a certain avoidance space for the wafer 50 and will not affect the clamping and rotation of the wafer 50.

[0074] Further, refer to Figure 3a and Figure 3b, a buffer 80 is provided between the pressure-maintaining structure 20 and the first surface to further improve the stability of the airflow in the gap 90. It is easy to understand that the buffer 80 is made of a flexible material, for example, the buffer 80 is a relatively elastic material such as rubber, silicone or resin. When the chuck 10 is rotating at high speed, the airflow in the gap 90 will collide with the inner wall of the pressure-maintaining structure 20 along the radial direction of the chuck 10 under the action of rotation, causing a sudden change in air pressure in the gap 90 at this position, and then, the edge of the wafer 50 near this position will jump violently. The buffer 80 is provided between the pressure-maintaining structure 20 and the first surface of the chuck 10 to avoid the collision of the high-speed airflow with the pressure-maintaining structure 20. The buffer 80 will play a certain blocking role on the airflow, that is, it has a certain turbulence or damping effect, so that the airflow is further stabilized in the gap 90, further improving the stability and controllability of the airflow in the gap 90, and the airflow will not have a sudden change in air pressure at the edge of the wafer 50, thereby improving the stability and safety of the wafer 50 during rotation.

[0075] like Figure 7 As shown, a curve diagram of the edge jitter of the suspended wafer 50 when the pressure-maintaining structure 20 is set and when the pressure-maintaining structure 20 is not set is shown under the same gas flow rate. The horizontal axis in the figure is the arc length from the test point to the starting point (which can also be understood as the distance the wafer 50 rotates), in microns; the vertical axis is the displacement of the wafer edge position jitter, in microns. Figure 7 It can be clearly seen that in the presence of the pressure-holding structure 20, the jitter displacement at the edge of the wafer 50 is relatively stable, and no large mutation occurs, that is, there is no sudden change in air pressure at the edge of the wafer 50, and the airflow stability is better; at the same time, in the absence of the pressure-holding structure 20, the maximum jitter displacement at the edge of the wafer 50 is 8 microns; in the presence of the pressure-holding structure 20, the maximum jitter displacement at the edge of the wafer 50 is 5 microns, and the stability of the wafer 50 is improved by 37.5%.

[0076] like Figure 3aAs shown, a buffer member 80 is provided between the pressure-holding structure 20 and the upper surface of the chuck 10, and the surface of the buffer member 80 facing the wafer 50 is a flat surface. Still taking the pressure-holding structure 20 as a flange provided on the circumferential side of the chuck 10 as an example for illustration: the side wall of the pressure-holding structure 20 close to the upper surface of the chuck 10 is the inner side wall of the pressure-holding structure 20, and the buffer member 80 is arranged around the inner side wall of the pressure-holding structure 20 at the junction position between the pressure-holding structure 20 and the upper surface of the chuck 10. For example, the buffer member 80 is a triangular prism arranged around the inner surface of the pressure-holding structure 20. Among them, the first side surface of the triangular prism is connected to the inner wall of the pressure-holding structure 20, the second side surface is connected to the upper surface of the chuck 10, and the third side surface faces the buffer member 80. Preferably, the first side surface and the second side surface are perpendicular to each other, and the height of the first side surface is equal to or slightly less than the height of the inner wall of the pressure-holding structure 20, so as to completely isolate the inner wall of the pressure-holding structure 20 from the air flow in the gap 90, ensuring that the air flow in the gap 90 will not collide with the pressure-holding structure 20 at all.

[0077] As Figure 3b As shown, a buffer member 80 is provided between the pressure-holding structure 20 and the upper surface of the chuck 10, and the surface of the buffer member 80 facing the wafer 50 is an arc surface. Still taking the pressure-holding structure 20 as a flange provided on the circumferential side of the chuck 10 as an example for illustration: the side wall of the pressure-holding structure 20 close to the upper surface of the chuck 10 is the inner side wall of the pressure-holding structure 20, and the buffer member 80 is arranged around the inner side wall of the pressure-holding structure 20 at the junction position between the pressure-holding structure 20 and the upper surface of the chuck 10. For example, the buffer member 80 is a quarter cylinder arranged around the inner surface of the pressure-holding structure 20. Among them, the first plane of the quarter cylinder is connected to the inner wall of the pressure-holding structure 20, the second plane is connected to the upper surface of the chuck 10, and the arc surface faces the buffer member 80. Preferably, the height of the first plane is equal to or slightly less than the height of the inner wall of the pressure-holding structure 20, so as to completely isolate the inner wall of the pressure-holding structure 20 from the air flow in the gap 90, ensuring that the air flow in the gap 90 will not collide with the pressure-holding structure 20 at all.

[0078] According to relevant experimental data, setting the buffer member 80 can significantly improve the stability of the wafer 50. Comparing with the case where the buffer member 80 is not set, setting the buffer member 80 can improve the stability of the wafer 50 by more than 20%, and setting the surface of the buffer member 80 facing the wafer 50 as an arc surface has a better effect than setting it as a flat surface, which can further improve the stability of the wafer 50 by more than 10%. In use, the setting method of the buffer member 80 can be adaptively selected according to the size of the wafer 50 and the requirements of the detection accuracy, and the present application does not make specific limitations on it.

[0079] Continue to refer to Figure 1, the clamping assembly 30 includes a connecting portion 32 and a clamping portion 31. The connecting portion 32 is connected to the chuck 10, and the clamping portion 31 clamps the edge of the wafer 50. For example, the connecting portion 32 and the clamping portion 31 are integrally formed structures. One end of the connecting portion 32 is fixedly connected to the circumferential side of the chuck 10, and the other end of the connecting portion 32 is provided with the clamping portion 31. The clamping portion 31 is used to clamp the edge of the wafer 50, so as to realize the connection between the chuck 10 and the wafer 50 through the clamping assembly 30. When the chuck 10 does not rotate, the wafer 50 can be stabilized above the chuck 10; when the chuck 10 starts to rotate, it can drive the wafer 50 to rotate synchronously with the chuck, and can limit the displacement of the wafer 50 in its radial direction, avoiding the wafer 50 from displacing or being thrown out along its radial direction during high-speed rotation.

[0080] Preferably, a plurality of clamping assemblies 30 are provided, and the plurality of clamping assemblies 30 are uniformly arranged along the circumferential direction of the chuck 10. In this way, it can be ensured that the wafer 50 is uniformly stressed in its circumferential direction. At the same time, the plurality of clamping assemblies 30 can form a block at each position in the circumferential direction of the wafer 50 to avoid displacement or detachment from the chuck 10 along the radial direction.

[0081] Furthermore, as Figures 4a to 4d shown, the clamping portion 31 is provided with an opening 33 facing the wafer 50, and the edge portion of the wafer 50 is located in the opening 33. The opening 33 includes a first wall 331, a second wall 332 and a third wall 333 connected in sequence.

[0082] It is easy to understand that a part of the edge of the wafer 50 is located in the opening 33. The first wall 331 and the third wall 333 can form a block for the wafer 50 in the height direction to avoid the wafer 50 from jumping violently along its axial direction; the second wall 332 can form a block for the wafer 50 in the radial direction to avoid the wafer 50 from displacing or detaching from the chuck 10 along its radial direction.

[0083] Preferably, the first wall 331 and the third wall 333 are inclined so that the opening 33 gradually increases in the direction close to the wafer 50, facilitating the installation of the wafer 50 into the opening 33; the size of the end of the opening 33 far from the wafer 50 is smaller, which can better limit the axial jump of the wafer 50 and is beneficial to improving the stability of the wafer 50 during rotation.

[0084] Optionally, as Figure 4a and 4d shown, the second wall 332 can be set as a plane; as Figure 4b and 4cAs shown, the second wall 332 can also be set as an arc surface, which can be set as an arc surface curved towards the direction close to the wafer 50, or can be set as an arc surface curved towards the direction away from the wafer 50. It is easy to understand that the setting method of the second wall 332 can be determined according to the specific shape of the wafer edge. For example, when the edge of the wafer 50 is circular, that is, when the wafer 50 is an R-type wafer, the second wall 332 can be set as an arc surface curved towards the direction away from the wafer 50; when the edge of the wafer 50 is right-angled, that is, when the wafer 50 is a T-type wafer, the second wall can be set as a plane, or can be set as an arc surface curved towards the direction close to the wafer 50. In use, it can be adaptively selected according to the situation of the wafer 50, and the present application does not make specific limitations on it.

[0085] Furthermore, the first wall 331 and / or the third wall 333 are set as stepped surfaces. It can be understood that, according to the wafer mounting process, only the first wall 331 can be set as a stepped surface, or only the third wall 333 can be set as a stepped surface, or both the first wall 331 and the third wall 333 can be set as stepped surfaces. For example, when the wafer 50 is placed into the opening 33, if the edge of the wafer 50 faces the first wall 331, only the first wall 331 can be set as a stepped surface; when the wafer 50 is placed into the opening 33, if the edge of the wafer 50 faces the third wall 333, only the third wall 333 can be set as a stepped surface; when the wafer 50 is placed into the opening 33 and the inclined state of the wafer 50 cannot be fixed, both the first wall 331 and the third wall 333 can be set as stepped surfaces. In this way, the stepped surface can play a certain blocking and buffering role on the wafer 50, avoiding the chamfer at the edge of the wafer 50 from directly colliding with the plane in the opening 33, resulting in damage to the clamping portion 31 due to the impact of the chamfer.

[0086] Take Figure 4d as an example to illustrate the shape of the stepped surface. The third wall 333 is set as an inclined surface with a gradient change, that is, the third wall 333 includes multiple planes, and the inclination degrees between the planes are different. For example, the third wall 333 can include three planes, which are connected in sequence. The inclination angle between the first plane and the second plane is different, and the inclination angle between the second plane and the third plane is different. Thus, after the three planes are connected, a stepped surface with a specific gradient change is formed, that is, the third wall 333. When the wafer 50 is placed into the opening 33, the chamfer at the edge position of the wafer 50 will come into contact with the position with a gradient change, and the inclination angle here will be close to the angle of the chamfer, so that the impact force of the chamfer can be reduced to a certain extent, avoiding the chamfer from "scraping" the wall of the opening 33.

[0087] Refer to Figure 1, the driving component 40 is connected to the chuck 10 and drives the chuck 10 to rotate. For example, the connection between the driving component 40 and the chuck 10 can be achieved through a flange 60 and a rotating shaft 70. Among them, the driving component 40 can be, for example, a motor. The output end of the motor can be connected to the input end of the rotating shaft 70, the output end of the rotating shaft 7 is connected to the flange 60, and the flange 60 is further connected to the chuck 10. Thus, under the action of the driving component 40, the chuck 10 can be driven to rotate synchronously. In use, the connection between the driving component 40 and the chuck 10 can also be achieved in other ways, and the present application does not make specific limitations on it.

[0088] A detection system according to another embodiment of the present invention includes the wafer clamping device as described above. It can be understood that the detection system can be used for particle detection, defect detection or edge detection of wafers, etc. As long as a system that needs to use the above wafer clamping device to clamp a wafer and complete a corresponding detection process is the detection system described in the present application and belongs to the detection system protected by this patent.

[0089] In the specification provided herein, a large number of specific details are described. However, it can be understood that the embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures, and technologies are not shown in detail so as not to obscure the understanding of this specification.

[0090] In addition, those of ordinary skill in the art can understand that although some embodiments described herein include certain features included in other embodiments rather than other features, the combination of features of different embodiments means that it is within the scope of the present invention and forms different embodiments.

[0091] Those skilled in the art should understand that although the present invention has been described with reference to exemplary embodiments, various changes can be made and its elements can be replaced with equivalents without departing from the scope of the present invention. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the present invention without departing from the substantial scope of the present invention.

Claims

1. A wafer clamping device, characterized in that, Comprising: A chuck, provided with a plurality of air holes penetrating the chuck along its axial direction. The plurality of air holes include a plurality of first air holes and a plurality of second air holes. The plurality of first air holes form a first pressure zone, and the plurality of second air holes form a second pressure zone. The first pressure zone and the second pressure zone suspend the wafer above the chuck; A pressure maintaining structure, fixedly connected to the chuck. The pressure maintaining structure is arranged in a ring shape and surrounds the outer periphery of the plurality of air holes; A clamping assembly, including a connecting portion and a clamping portion. The connecting portion is connected to the chuck, and the clamping portion clamps the edge of the wafer; A driving assembly, connected to the chuck and driving the chuck to rotate.

2. The device according to claim 1, characterized in that The first air hole is an air outlet hole, and the first pressure zone is a pressurizing zone; and / or The second air hole is an air suction hole, and the second pressure zone is a decompressing zone.

3. The device according to claim 2, characterized in that, The air outlet hole satisfies: Q = n / 100 + 4.2 Wherein, Q is the gas flow rate of the air outlet hole, with the unit of L / min, and n is the rotation speed of the chuck, with the unit of rpm.

4. The device according to claim 1, characterized in that, The plurality of air holes are arranged radially starting from the center of the chuck; or The plurality of air holes are arranged concentrically with the center of the chuck as the center.

5. The device according to claim 4, characterized in that, The first pressure zone and the second pressure zone are arranged intersectingly or spaced apart.

6. The device according to claim 1, characterized in that, The pressure maintaining structure is arranged on the circumferential side of the chuck and protrudes from the first surface of the chuck. The first surface is the surface of the chuck facing the wafer.

7. The device according to claim 6, characterized in that, A buffer member is provided between the pressure maintaining structure and the first surface. The surface of the buffer member facing the wafer is a flat surface or an arc surface.

8. The device according to claim 1, characterized in that A plurality of the clamping assemblies are provided, and the plurality of clamping assemblies are evenly arranged along the circumferential direction of the chuck.

9. The device according to claim 8, wherein The clamping portion is provided with an opening facing the wafer, and the edge portion of the wafer is located within the opening; The opening includes a first wall body, a second wall body, and a third wall body connected in sequence. The second wall body is arranged as a flat surface or an arc surface; and / or The first wall body and / or the third wall body is arranged as a stepped surface.

10. A detection system, characterized in that, Comprising the wafer clamping device according to any one of claims 1-9.

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