CN110695849B - A wafer thickness measuring device and grinding machine - Google Patents

Abstract

The invention discloses a wafer thickness measurement device and a grinding machine. The measurement device includes a main body structure, a liftable suspension structure and an optical sensor assembly. The suspension structure is mounted on the lower part of the main body structure, and the lower part of the main body structure is slidably arranged In the groove of the suspension structure, the main structure is provided with a first fluid pipeline leading to the junction of the main structure and the suspension structure for filling the groove with the first fluid to lift the suspension structure. The first through holes on the upper and lower surfaces are used for accommodating the optical sensor assembly. The bottom of the groove of the suspension structure is provided with a second through hole under the first through hole to pass the light path output by the optical sensor assembly. There is a second fluid pipeline to realize that the chamber formed by the bottom surface of the main structure, the bottom surface of the optical sensor assembly, the inner surface of the groove and the second through hole is filled with the second fluid. It can effectively improve the accuracy and precision of wafer thickness measurement.

Description

A wafer thickness measuring device and grinding machine

technical field

The invention relates to the technical field of wafer ultra-precision grinding, in particular to a wafer thickness measurement device and a grinding machine.

Background technique

The semiconductor industry currently manufactures semiconductor chips by forming electronic circuits on the surface of semiconductor wafers. Before the wafer is divided into semiconductor chips, the back surface opposite to the device surface on which the electronic circuit is formed is ground by a grinding processing apparatus, thereby reducing the wafer to a predetermined thickness. The grinding of the backside of the wafer can reduce the volume of the chip package, reduce the height of the package, and improve the thermal diffusion efficiency, electrical performance and mechanical properties of the chip, thereby reducing the processing volume of the chip, and the thickness of the chip after the backside is thinned can even reach the initial 5% or less of the thickness.

In order to grind the wafer to the target thickness, it is necessary to measure the thickness of the wafer during the grinding process, which can be achieved by non-contact optical measurement. Optical measurement of wafer thickness involves irradiating a predetermined frequency of laser light on the surface of the wafer, and measuring the thickness based on the waveform of the interference wave formed by the reflected light from the wafer surface and the reflected light from the back surface after laser irradiation. During the grinding process, there will be water films, water droplets, particle contaminants, etc. on the wafer surface, which will change the optical path of the optical measurement, interfere with the non-contact measurement, and affect the measurement accuracy. In conclusion, there are problems of inaccurate measurement of wafer thickness and low precision in the prior art.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a wafer thickness measurement device and a grinding machine, which aim to solve at least one of the technical problems existing in the prior art.

A first aspect of the embodiments of the present invention provides a wafer thickness measurement device, including: a main body structure, a liftable suspension structure, and an optical sensor assembly, the suspension structure is mounted on the lower part of the main body structure, and the lower part of the main body structure is slidably disposed on the In the groove of the suspension structure, the main structure is provided with a first fluid pipeline leading to the junction of the main structure and the suspension structure for filling the groove with the first fluid to lift the suspension structure. The first through holes on the upper and lower surfaces are used for accommodating the optical sensor assembly. The bottom of the groove of the suspension structure is provided with a second through hole under the first through hole to pass the light path output by the optical sensor assembly. The suspension structure is provided with a second through hole. The second fluid pipeline is used to realize that the chamber formed by the bottom surface of the main structure, the bottom surface of the optical sensor assembly, the inner surface of the groove and the second through hole is filled with the second fluid.

In one embodiment, the main body structure includes a middle portion, an annular upper flange extending outward from an upper end of the middle portion, and an annular lower flange extending outward from a lower end of the middle portion, the lower flange being located in a groove of the suspension structure There is a hanging structure inside.

In one embodiment, the middle part is provided with a first through hole and a first fluid pipeline, the first fluid pipeline is not communicated with the first through hole, and the outlet of the first fluid pipeline is provided on the upper surface of the lower flange Connection with the side of the middle part.

In one embodiment, the suspension structure includes an upwardly open cylindrical portion and an annular inner flange extending inwardly from an upper end of the cylindrical portion, the cylindrical portion and the inner flange form the groove to limit the lower flange of the main structure to a limit. in this slot.

In one embodiment, the cylindrical portion is provided with a second through hole and a second fluid pipeline, and the second fluid pipeline communicates with the second through hole.

In one embodiment, the optical sensor assembly includes an optical sensor and a transparent baffle below the optical sensor.

In one embodiment, the suspension structure is further provided with a first sealing ring surrounding the inner side surface of the inner flange, so as to realize the sliding fit between the inner side surface of the inner flange and the outer side surface of the intermediate portion Hermetically sealed.

In one embodiment, the main body structure is further provided with a third sealing ring surrounding the outer side surface of the lower flange, so that when the outer side surface of the lower flange is slidably matched with the inner side surface of the barrel portion achieve a hermetic seal.

In one embodiment, the wafer thickness measurement device further includes a movable support connected to the main body structure.

A second aspect of the embodiments of the present invention provides a grinding machine, including:

A grinding mechanism for making the grinding wheel abut the wafer to grind and thin the wafer;

The suction cup is used to hold the wafer and drive the wafer to rotate;

a turntable, used to carry a preset number of the suction cups and drive all the suction cups to rotate as a whole;

Wherein, the above-mentioned wafer thickness measuring device is provided on the turntable.

The beneficial effects of the embodiments of the present invention include: the accuracy and precision of wafer thickness measurement can be effectively improved.

Description of drawings

The advantages of the present invention will become clearer and easier to understand through the detailed description in conjunction with the following drawings, but these drawings are only schematic and do not limit the protection scope of the present invention, wherein:

1 is a schematic structural diagram of a grinding machine according to an embodiment of the present invention;

FIG. 2 is a partial structural schematic diagram of a grinding machine provided by an embodiment of the present invention;

3 is a schematic diagram of a measurement principle provided by an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a wafer thickness measurement device provided by an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a wafer thickness measurement device provided by an embodiment of the present invention;

FIG. 6 is a schematic flowchart of an operation method provided by an embodiment of the present invention.

Detailed ways

The technical solutions of the present invention will be described in detail below with reference to specific embodiments and accompanying drawings. The embodiments described herein are specific embodiments of the present invention, used to illustrate the concept of the present invention; these descriptions are all explanatory and exemplary, and should not be construed as limiting the embodiments of the present invention and the protection scope of the present invention . In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims of the present application and the description thereof, and these technical solutions include adopting any modifications made to the embodiments described herein. Obvious alternative and modified technical solutions. It should be understood that, unless otherwise specified, for ease of understanding, the following descriptions of the specific embodiments of the present invention are based on the natural state that the relevant equipment, devices, components, etc. are in the original static state without external control signals and driving forces. describe.

In order to illustrate the technical solutions of the present invention, the following specific embodiments are used for description.

In the chip preparation process, electronic circuits are formed on the surface of the wafer to achieve predetermined chip functions, and the backside of the surface is ground to realize the thinning of the backside of the wafer. The backside grinding of the wafer is suitably performed by a grinding station provided in one embodiment as shown in FIG. 1 .

As shown in FIG. 1 , a grinding machine provided by an embodiment of the present invention includes:

Grinding mechanism 3, for making the grinding wheel abut the wafer to grind and thin the wafer;

The suction cup 1 is used to hold the wafer and drive the wafer to rotate;

The turntable 2 is used to carry a preset number of the suction cups and drive all the suction cups to rotate as a whole;

Wherein, the turntable 2 is provided with a wafer thickness measuring device 4 .

As an embodiment, a plurality of suction cups 1 are arranged on the turntable 2 at equal intervals in the circumferential direction, each suction cup 1 can rotate independently, and the turntable 2 can rotate around its vertical central axis to drive the plurality of suction cups 1 to rotate and move as a whole Thus, the position of the suction cup 1 can be switched between different stations.

As shown in FIG. 1 , three suction cups 1 that can be rotated independently are evenly distributed on the turntable 2 , which are the first suction cup, the second suction cup and the third suction cup for sucking wafers, and all the suction cups 1 have the same structure. Porous ceramic chuck for vacuum adsorption of wafers. The wafer is adsorbed to the horizontal adsorption surface of the vacuum chuck 1 to hold the wafer, and the back surface of the wafer is sequentially subjected to rough grinding and fine grinding by the grinding mechanism 3 .

The lines connecting the centers of the three suction cups 1 and the center of the turntable 2 form an included angle of 120° with each other. The 3 suction cups 1 correspond to 3 stations, namely the rough grinding station 11, the fine grinding station 12 and the loading and unloading station 13, of which the two stations opposite to the grinding wheel are used for rough grinding and fine grinding, respectively. The next station is used for wafer loading and unloading and cleaning. The rotation of the turntable 2 can drive the three suction cups 1 to switch between the three stations, so that the suction cups 1 carry the wafers according to the loading and unloading stations 13-rough grinding station 11-finishing station 12-loading and unloading station 13 cyclic movement in sequence. This embodiment uses a rotary turntable 2 for wafer grinding, and realizes automatic loading and unloading, continuous grinding and cleaning of wafers through repeated cycles, and has the advantages of high material removal rate, less damage to the wafer surface, and easy automation.

As shown in FIG. 1 , the grinding mechanism 3 is composed of a rough grinding part 31 and a fine grinding part 32 , the rough grinding part 31 is provided with a rough grinding wheel for rough grinding the wafer, and the fine grinding part 32 is provided with a rough grinding wheel for Round fine grinding wheel for fine grinding. The grinding process is to press the grinding wheel against the surface of the wafer and rotate it to grind off a certain thickness.

The rough grinding part 31 includes a rough grinding wheel with a cup-shaped structure, a rough grinding spindle, a rough grinding spindle seat and a rough grinding feeding mechanism. The rough grinding wheel is connected to the bottom of the rough grinding spindle, so that the rough grinding spindle drives the rough grinding wheel to rotate so as to realize the rotary grinding of the wafer surface by the rough grinding wheel. The rough grinding spindle is connected with the rough grinding feed mechanism through the rough grinding spindle seat to achieve Moving up and down, the rough grinding wheel is controlled by the rough grinding feed mechanism to approach or move away from the wafer for axial plunge feed grinding. In this embodiment, the rough grinding wheel may be a diamond grinding wheel, which has a rough surface to achieve rapid wafer grinding and reduce wafer thinning time. During rough grinding, the feed rate of the rough grinding wheel relative to the wafer is 4 to 10 μm/s to achieve high-speed feed, and the rotational speed of the rough grinding wheel is 2000 to 4000 rpm. The radius of the rough grinding wheel matches the radius of the wafer and can be 1 to 1.2 times the radius of the wafer.

The fine grinding part 32 includes a cup-shaped fine grinding wheel, a fine grinding spindle, a fine grinding spindle seat and a fine grinding feeding mechanism. The fine grinding wheel is connected to the bottom of the fine grinding spindle, so that the fine grinding spindle drives the fine grinding wheel to rotate so as to realize the rotary grinding of the wafer surface by the fine grinding wheel. The fine grinding spindle is connected with the fine grinding feed mechanism through the fine grinding spindle seat to achieve Moving up and down, the finishing grinding wheel is controlled by the finishing feed mechanism to approach or move away from the wafer for axial plunge feed grinding. In this embodiment, the fine grinding wheel can be a diamond grinding wheel, and its surface roughness is lower than that of the rough grinding wheel. Since rough grinding quickly removes the surface material of the wafer, serious surface defects and losses will occur. The fine surface of the fine grinding wheel is used for low-speed grinding Grinding to reduce wafer surface damage layer thickness and improve wafer surface quality. During fine grinding, the feed rate of the fine grinding wheel relative to the wafer is 0.1 to 1 μm/s to achieve low-speed feed to improve the grinding accuracy, and the rotational speed of the fine grinding wheel is 2000 to 4000 rpm. The radius of the finishing wheel matches the radius of the wafer and can be 1 to 1.2 times the radius of the wafer.

When the turntable 2 is rotated by a predetermined angle, the wafer held on the chuck 1 is conveyed to the rough grinding station 11 below the rough grinding section 31 , and the back surface of the wafer is rough ground by a rough grinding wheel at the rough grinding station 11 . Then, the turntable 2 is rotated again by a predetermined angle, and the wafer is transported to the fine grinding station 12 below the fine grinding part 32 for secondary processing, and the back surface of the wafer is finely ground by the fine grinding wheel at the fine grinding station 12 . The backside grinding process of the wafer is specifically as follows: the grinding wheel is lowered by the feeding mechanism to realize grinding feed, the rotation of the suction cup 1 drives the wafer to rotate, and the rotating grinding wheel is pressed against the backside of the wafer for grinding. During backside grinding, a grinding fluid supply device is used to spray grinding fluid on the surface of the wafer to assist in grinding, and the grinding fluid may be deionized water.

In order to realize the thinning of the wafer to the target thickness, the wafer thickness is measured by the wafer thickness measuring device 4 during the grinding process. As shown in FIG. 1 , the wafer thickness measurement device 4 is used for non-contact measurement of wafer thickness in the fine grinding station 12 .

As shown in FIGS. 2 and 3 , a wafer thickness measurement device 4 provided by an embodiment of the present invention includes a movable bracket 5 and a measurement body 6 located at the front end of the bracket 5 .

The support 5 includes a swivel base 51 and a swing arm 52 mounted on the swivel base 51 and rotatable horizontally around the central axis of the swivel base 51. The measurement body 6 is mounted on the moving end of the swing arm 52 and is set downward to sweep the surface of the wafer w And measure the thickness of the wafer w underneath at multiple measurement points.

The measurement main body 6 includes: a load-bearing main body structure 7 , a liftable suspension structure 8 and an optical sensor assembly 9 , the suspension structure 8 is mounted on the lower part of the main body structure 7 , and the lower part of the main body structure 7 is slidably arranged in the groove 81 of the suspension structure 8 , the main body structure 7 is provided with a first fluid pipeline 71 leading to the junction of the main body structure 7 and the suspension structure 8 for filling the first fluid into the groove 81 to lift the suspension structure 8, and the main body structure 7 is provided with A first through hole 72 for accommodating the optical sensor assembly 9 runs through its upper and lower surfaces, and the bottom of the groove 81 of the suspension structure 8 is provided with a second through hole 82 under the first through hole 72 to pass through the optical sensor assembly 9 The optical path 91 output from the bottom end, the suspension structure 8 is provided with a second fluid pipeline 83 to realize that the cavity 84 formed by the bottom surface of the main structure 7, the bottom surface of the optical sensor assembly 9, the inner surface of the groove 81 and the second through hole 82 is filled with the first fluid. two fluids.

The movable bracket 5 is connected with the main body structure 7 to support the main body structure 7 and drive the measurement main body 6 to move through the main body structure 7 .

In this embodiment, the wafer thickness measuring device 4 has two states, which are:

1) The lifting state shown in FIG. 4: the main body structure 7 is fixed, the first fluid pipeline 71 is fed with high-pressure gas or liquid, and under the action of air pressure or hydraulic pressure, the suspension structure 8 is lifted up to increase the bottom surface of the measurement body 6 The distance from the wafer w thus enables unobstructed movement, and the second fluid line 83 disconnects the fluid supply at this time.

2) The measurement state shown in Figure 5: the main body structure 7 is fixed, the first fluid pipeline 71 is disconnected from the fluid supply, the suspension structure 8 is dropped and hung on the main body structure 7, and the second fluid pipeline 83 is connected to high pressure Gas or liquid, the gas or liquid flows to the surface of the wafer w through the second through hole 82 to flush the surface of the wafer w and wash away the contaminants that obstruct the optical path 91, so as to realize the space where the optical path 91 located above the wafer w is located. Filled with the same gas or liquid, the optical path 91 propagates in the same medium, so that the interference wave formed by the reflected light on the upper and lower surfaces of the wafer w is only related to the thickness of the wafer w, which improves the accuracy and precision of thickness measurement.

In this embodiment, the suspension structure 8 is controlled to switch between two extreme positions through the first fluid pipeline 71 and the second fluid pipeline 83 .

The measurement principle of the device is as follows: the measurement optical path 91 of the optical sensor assembly 9 passes through the second through hole 82, irradiates the wafer w with infrared light, and calculates the thickness of the substrate according to the different reflected light on the upper and lower surfaces of the wafer w.

In the embodiment of the present invention, a fluid channel is arranged in the measurement optical path 91 of the non-contact wafer thickness measurement device 4 to ensure that the measurement light transmission process will not be affected by interference factors such as liquid film, liquid beads or particles on the wafer surface. The effect of interference factors is eliminated, and the accuracy and precision of wafer thickness measurement can be effectively improved.

As shown in FIGS. 4 and 5 , the main body structure 7 includes a middle portion 73 , an annular upper flange 74 extending outward from the upper end of the middle portion 73 , and an annular lower flange 75 extending outward from the lower end of the middle portion 73 , The lower flange 75 is located in the groove 81 of the suspension structure 8 to hang the suspension structure 8 .

The middle portion 73 is provided with a first through hole 72 and a first fluid pipeline 71 , the first fluid pipeline 71 is not communicated with the first through hole 72 , and the outlet 711 of the first fluid pipeline 71 is provided on the lower convex The connection between the upper surface of the edge 75 and the side surface of the middle portion 73 .

In one embodiment, as shown in the figure, the first fluid pipeline 71 and the first through hole 72 are both arranged in parallel along the vertical direction, and the first fluid pipeline 71 is used to spray the high-pressure first fluid to the suspension structure 8 to Under the action of fluid pressure, the suspension structure 8 is lifted, and the first joint 712 of the first fluid pipeline 71 is connected to the upper surface of the main body structure 7 .

As shown in FIGS. 4 and 5 , the main body structure 7 is further provided with a third sealing ring 76 surrounding the outer surface of the lower flange 75 to achieve airtightness when the outer surface of the lower flange 75 is slidably fitted with the inner surface of the cylindrical portion 85 . seal.

As shown in FIGS. 4 and 5 , the suspension structure 8 includes an upwardly open cylindrical portion 85 and an annular inner flange 86 extending inward from the upper end of the cylindrical portion 85 . The cylindrical portion 85 and the inner flange 86 form the groove 81 In order to confine the lower flange 75 of the main body structure 7 in the groove 81 .

In one embodiment, as shown in the figure, the edge of the bottom surface of the inner flange 86 is provided with an annular recess 87 so that the first fluid ejected from the first fluid pipeline 71 can quickly contact the bottom surface of the inner flange 86 and move toward the bottom surface of the inner flange 86. The bottom surface exerts upward pressure to lift the suspension structure 8 .

The cylindrical portion 85 is provided with a second through hole 82 and a second fluid pipeline 83 , and the second fluid pipeline 83 communicates with the second through hole 82 . The second through hole 82 penetrates the upper and lower surfaces of the bottom wall of the cylindrical portion 85. The second through hole 82 can be composed of a cylindrical hole and a circular frustum hole located below the cylindrical hole. The diameter of the upper surface of the frustum hole is larger than the diameter of the lower surface. .

In one embodiment, the bottom wall of the cylindrical portion 85 is provided with a second fluid pipeline 83 extending in the horizontal direction, the outlet 831 of the second fluid pipeline 83 is provided on the side wall of the second through hole 82, The fluid pipeline 83 is used to fill the chamber 84 formed by the bottom surface of the main structure 7 , the bottom surface of the optical sensor assembly 9 , the inner surface of the groove 81 and the second through hole 82 with the second fluid. The second joint 832 of the second fluid pipeline 83 Connected to the outer side of the suspension structure 8 .

As shown in FIGS. 4 and 5 , the suspension structure 8 is further provided with a first sealing ring 88 surrounding the inner surface of the inner flange 86 , so that the inner surface of the inner flange 86 is slidably matched with the outer surface of the intermediate portion 73 to realize air hermetically sealed.

As shown in FIGS. 4 and 5 , the suspension structure 8 is further provided with a second sealing ring 89 at the position where the cylindrical portion 85 is combined with the inner flange 86 .

As shown in FIGS. 4 and 5 , the optical sensor assembly 9 includes an optical sensor 92 that can emit incident light to the surface of the wafer w and receive the emitted light reflected from the wafer w, and a transparent baffle 93 located below the optical sensor 92 .

The transparent baffle 93 is disposed at the bottom end of the first through hole 72 and airtightly connected to the middle portion 73 to prevent the second fluid from entering the first through hole 72 and contaminating the optical sensor 92 accommodated in the first through hole 72 . The material of the transparent baffle 93 can be glass, plastic, crystal and other light-transmitting materials. While ensuring that the measurement optical path 91 can pass through, the gas or liquid in the chamber 84 is isolated from the optical sensor 92 to avoid damage to the sensor.

The optical sensor 92 is respectively connected to the external laser light source and the measurement and control instrument through the optical fiber to realize optical measurement.

As shown in FIG. 6, the working process of the grinding machine includes: placing the wafer in the loading and unloading station 13, rotating the turntable 2 by 120° to move the wafer to the rough grinding station 11 for rough grinding, and processing until the wafer reaches After the rough grinding of the first predetermined thickness is completed, the first fluid pipeline 71 is fed with high-pressure gas or liquid to lift the suspension structure 8, the turntable 2 is rotated by 120°, and the wafer is moved to the fine grinding station 12 for the first stage of fine grinding, Fine grinding until the wafer reaches the second predetermined thickness, lift the fine grinding wheel to stop fine grinding, the support 5 of the wafer thickness measuring device 4 drives the measuring body 6 to move from the initial position to the top of the wafer along the arc direction, The second fluid line 83 is fed with high-pressure gas or liquid and the first fluid line 71 is closed to allow the suspension structure 8 to drop down. The support 5 drives the measurement body 6 to move from the edge of the wafer to a position close to the center along the arc direction to Thickness data is collected at multiple measurement points. After the thickness measurement is completed, the second fluid pipeline 83 is closed and the first fluid pipeline 71 is filled with high-pressure gas or liquid to lift the suspension structure 8 and move the measurement body 6 back to the initial position. The fine grinding parameters are adjusted and the second stage fine grinding is carried out. After fine grinding until the wafer reaches the third predetermined thickness, smooth grinding is performed, and then the fine grinding wheel is lifted to end the grinding process, and the turntable is rotated 120° or reversed. Rotate 240° to move the wafer to the loading and unloading station 13, perform cleaning of the wafer and the suction cup 1, and remove the wafer after the cleaning is completed.

Among them, the lifting state of the wafer thickness measuring device 4 is suitable for the process of the turntable 2 performing the rough and fine grinding conversion. The bottom surface of the device is properly lifted to increase the distance from the wafer and reduce the contact between the bottom surface and the wafer during the rotation process. risk of interference.

The measurement state is used for in-situ measurement of wafer thickness when the polishing process is paused. At this time, the bottom surface of the device is lowered to shorten the distance to the wafer, and the chamber 84 is filled with the second fluid to form a stable flow field. The environment improves Measurement accuracy.

To sum up, in the embodiment of the present invention, the gas or liquid channel provided in the chamber 84 where the measurement optical path 91 is located can eliminate the interference of the wafer surface liquid film, liquid beads, particles and other pollutants on the measurement accuracy and stability, and improve the measurement accuracy. precision. In addition, the suspension structure 8 has two limit states. The lifting state can effectively avoid the risk of collision between the measuring device and the suction cup 1, the turntable 2 or the wafer and other components. The measuring state can ensure that the measurement optical path 91 is in a stable gas or liquid environment. In addition, the distance between the optical sensor 92 and the wafer remains unchanged, and the position of the optical sensor 92 is fixed, which can avoid vibration and thus cause measurement interference.

The accompanying drawings in the present specification are schematic diagrams to assist in explaining the concept of the present invention, and schematically show the shapes of various parts and their mutual relationships. It should be understood that, in order to clearly represent the structures of the various components of the embodiments of the present invention, the drawings are not drawn according to the same scale, and the same reference numerals are used to denote the same parts in the drawings.

In the description of this specification, reference to the terms "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples", etc., is meant to incorporate the embodiments A particular feature, structure, material, or characteristic described by an example or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, The scope of the invention is defined by the claims and their equivalents.

Claims (10)

1. A wafer thickness measuring device, comprising: the major structure, liftable suspended structure and optical sensor subassembly, the suspended structure carries in the major structure lower part, major structure lower part slidable ground sets up in suspended structure's inslot, be equipped with the first fluid pipeline that accesss to major structure and suspended structure's handing-over department in the major structure and be used for filling into first fluid in order to promote this suspended structure to this inslot, the major structure is equipped with and runs through it, the first through-hole that is used for holding optical sensor subassembly of lower surface, suspended structure's tank bottom is equipped with the second through-hole in first through-hole below in order to pass through the light path by optical sensor subassembly output, be equipped with second fluid pipeline in the suspended structure in order to realize by the major structure bottom surface, optical sensor subassembly bottom surface, be filled with the second fluid in the cavity that groove inner face and second through.

2. The wafer thickness measuring device of claim 1, wherein the body structure includes a middle portion, an annular upper flange extending outwardly from an upper end of the middle portion, and an annular lower flange extending outwardly from a lower end of the middle portion, the lower flange being positioned within the slot of the suspension structure to overhang the suspension structure.

3. The wafer thickness measuring apparatus according to claim 2, wherein the middle portion is provided with a first through hole and a first fluid line, the first fluid line is not communicated with the first through hole, and an outlet of the first fluid line is provided at a junction of the upper surface of the lower flange and the side surface of the middle portion.

4. The wafer thickness measuring apparatus of claim 2, wherein the suspension structure includes an upwardly open barrel and an annular inner flange extending inwardly from an upper end of the barrel, the barrel and inner flange defining the slot to retain the lower flange of the body structure within the slot.

5. The wafer thickness measuring apparatus according to claim 4, wherein the barrel portion is provided with a second through hole and a second fluid line, the second fluid line communicating with the second through hole.

6. The wafer thickness measuring device of claim 1, wherein the optical sensor assembly includes an optical sensor and a transparent baffle below the optical sensor.

7. The wafer thickness measuring device of claim 4, wherein the suspension structure is further provided with a first sealing ring surrounding an inner side surface of the inner flange to achieve a hermetic seal when the inner side surface of the inner flange is in sliding engagement with an outer side surface of the intermediate portion.

8. The wafer thickness measuring device of claim 4, wherein the body structure is further provided with a third seal ring surrounding the outer side surface of the lower flange to effect a hermetic seal when the outer side surface of the lower flange is in sliding engagement with the inner side surface of the barrel.

9. The wafer thickness measurement device of claim 1, further comprising a movable support coupled to the body structure.

10. A grinding machine table, comprising:

the grinding mechanism is used for enabling the grinding wheel to abut against the wafer so as to grind and thin the wafer;

the sucking disc is used for holding the wafer and driving the wafer to rotate;

the rotary table is used for bearing a preset number of the suckers and driving all the suckers to integrally rotate;

wherein the turntable is provided with a wafer thickness measuring device as claimed in claims 1 to 9.

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