Wafer grinding device

Abstract

To provide a wafer thickness measuring device that can prevent erroneous measurements due to adhesion of grinding powder, water, etc. when measuring thickness.SOLUTION: In a grinding device 1 of a wafer 9 which includes a cassette 2 for storing a wafer 9, a conveying portion 3 consisting of a first conveying portion 31 and a second conveying portion 35 for conveying the wafer 9 removed from the cassette 2, a grinding portion 4 for placing and grinding the wafer 9 conveyed by the conveying portion 3, and a cleaning portion 5 provided between the cassette 2 and the grinding portion 4 for cleaning the wafer 9 ground by the grinding portion 4, a thickness measuring portion 6 for measuring the thickness of the wafer 9 is provided in the conveying path between the cleaning portion 5 and the cassette 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a wafer grinding device that is capable of measuring the thickness of a wafer ground by a lapping machine. [Background technology]

[0002] Conventionally, there are grinding apparatuses having a function of measuring the thickness of a ground wafer, such as those described in the following patent documents.

[0003] Specifically, this patent document discloses an apparatus that includes a grinding section that grinds wafers that are adsorbed to a chuck table, a cleaning section that cleans the wafers that have been ground in the grinding section, and a thickness measuring section that measures the thickness of the wafers that have been cleaned in the cleaning section, and after the ground wafers have been cleaned, the thickness is measured by the thickness measuring section provided within the grinding section. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-176802 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the device described in the above patent document has the following problems.

[0006] That is, in the device described in the above patent document, the thickness of the wafer is measured within the grinding section, for example, while the wafer is placed on a chuck table. Therefore, atomized grinding powder and water scattered during grinding may adhere to the wafer, which may cause errors in the measurement, particularly when the thickness is measured optically.

[0007] Furthermore, when the thickness measuring unit is provided inside the grinding unit in this way, it becomes difficult to install a large-scale thickness measuring device because the grinding unit is equipped with many devices such as spindles and grinding wheels.

[0008] Furthermore, if it is necessary to measure the thickness of a dress plate or the like in addition to measuring the thickness of the wafer, a separate thickness measurement unit for the dress plate must be installed, which may complicate the structure.

[0009] Therefore, in order to solve the above problems, the present invention aims to provide a wafer grinding device that can prevent erroneous measurements due to adhesion of grinding powder, water, etc. when measuring the thickness of a wafer, and that can also measure the thickness of a dress plate. [Means for solving the problem]

[0010] That is, in order to solve the above-mentioned problems, the present invention provides a wafer grinding device comprising a cassette for storing wafers, a transport section for transporting wafers removed from the cassette, a grinding section for placing and grinding wafers transported by the transport section, and a cleaning section provided between the cassette and the grinding section for cleaning the wafers ground by the grinding section, wherein a thickness measuring section for measuring the thickness of the wafers is provided in the transport path between the cleaning section and the cassette.

[0011] With this configuration, the thickness measurement unit is located away from the grinding unit, so grinding powder and water from the grinding unit do not adhere to the wafer. This makes it possible to accurately measure the thickness of the wafer. Furthermore, because the thickness measurement unit and the grinding unit are located separately, other wafers can be ground while the thickness is being measured.

[0012] In the invention, a wall surface is provided between the cleaning section and the thickness measuring section on the transport path.

[0013] With this configuration, even if the cleaning section and thickness measurement section are placed adjacent to each other, the wall surface can prevent water from splashing during cleaning, thereby preventing erroneous measurements due to water adhesion.

[0014] Furthermore, a first wall surface portion is provided between the cleaning section and the thickness measurement section on the transport path, and a second wall surface portion having a slit for passing the wafer is provided on the side of the first wall surface portion, so that the wafer is transported from the cleaning section to the thickness measurement section through the slit in the second wall surface portion.

[0015] With this configuration, the wafer passes through the slit in the second wall portion on the side of the first wall portion, so that water can be prevented from splashing onto the thickness measurement portion.

[0016] In addition, the transport unit is configured to include a first transport unit that removes wafers from the cassette, and a second transport unit that receives the wafers transported by the first transport unit, transports them to the grinding unit, and passes the ground wafers through the cleaning unit, and the wafers cleaned in the cleaning unit are transported to the thickness measurement unit using the first transport unit.

[0017] With this configuration, it becomes possible to transport another wafer from the grinding section to a cleaning section or the like while the thickness of the ground wafer is being measured. [Effects of the Invention]

[0018] According to the present invention, since the thickness measurement unit is located at a position away from the grinding unit, grinding powder and water from the grinding unit do not adhere to the wafer. This makes it possible to accurately measure the thickness of the wafer. Furthermore, since the thickness measurement unit and the grinding unit are located separately, other wafers can be ground while the thickness is being measured. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic plan view of a wafer grinding device according to an embodiment of the present invention; [Figure 2] FIG. 10 is a diagram showing a first conveying section in the same embodiment. [Figure 3] FIG. 10 shows a wall portion in the same embodiment. [Figure 4] FIG. 10 shows the transport to the thickness measurement unit in the same configuration. [Figure 5] Schematic diagram of the thickness measurement unit in the same configuration [Figure 6] Schematic diagram showing the thickness measurement unit and dress plate in the same configuration DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0021] As shown in FIG. 1, a grinding apparatus 1 for wafers 9 in this embodiment includes a cassette 2 for storing a plurality of wafers 9, a transport unit 3 for removing and transporting wafers 9 from the cassette 2, and a grinding unit 4 for grinding the wafers 9 transported by the transport unit 3. Characteristically, a cleaning unit 5 for cleaning the wafers 9 is provided along a transport path for returning the wafers 9 ground by the grinding unit 4 to the cassette 2, and a thickness measuring unit 6 for measuring the thickness of the wafers 9 is provided along the transport path between the cleaning unit 5 and the cassette 2. By providing the thickness measuring unit 6 at a position separate from the grinding unit 4, grinding dust and water are prevented from scattering into the thickness measuring unit 6, enabling accurate thickness measurements. Furthermore, by providing the thickness measuring unit 6 at a position independent of the grinding unit 4, thicknesses of items other than the wafers 9, such as a dress plate 8 (see FIG. 6), can also be measured there. This embodiment will be described in detail below.

[0022] First, the cassette 2 is configured to be able to accommodate a plurality of wafers 9, and is configured so that the wafers 9 can be accommodated in a plurality of slits that are opened in the horizontal direction.

[0023] The transport section 3 is configured to remove the wafer 9 from the cassette 2 and transport it to the grinding section 4, and is here divided into a first transport section 31 and a second transport section 35.

[0024] 2, the first transport unit 31 is configured to include a placement unit 32 on which the wafer 9 is placed, and an arm 33 that moves the placement unit 32 in the vertical and horizontal directions. The placement unit 32 has a fork-shaped opening 32A that allows it to support the bottom side of the wafer 9, while the arm 33 has two connected arm elements that can be rotated, extended, and raised and lowered by a cylinder, a motor, or the like.

[0025] 1 receives the wafer 9 transferred from the first transfer unit 31 and transfers it to the grinding unit 4, and is configured to pick up the wafer 9 placed on the placement unit 32 of the first transfer unit 31 from above and move it in a direction perpendicular to the transfer direction in the first transfer unit 31. The wafer 9 transferred by the second transfer unit 35 is then moved above the chuck table 41 of the grinding unit 4, where it is lowered and placed on the chuck table 41.

[0026] Here, the transport path from the cassette 2 to the transfer position to the second transport section 35 will be referred to as the "first transport path 36A," and the transport path from that transfer position to the placement position of the chuck table 41 will be referred to as the "second transport path 36B."

[0027] The grinding unit 4 (see FIG. 1) is configured to include a chuck table 41, a spindle 42, and a grinding wheel plate 43. Of these, the chuck table 41 is configured to be able to adsorb the wafer 9 while it is placed thereon, rotate about a central axis, and swing between a rough grinding position 44A, a finish grinding position 44B, and an entrance / exit position 44C.

[0028] The spindle 42 has a grinding wheel plate 43 attached to its lower side, and is configured to move the grinding wheel plate 43 up and down and also rotate the grinding wheel plate 43. The grinding wheel plate 43 has grinding wheels provided in the circumferential direction on its lower surface, and when the chuck table 41 is rotated, the grinding wheel plate 43 is rotated at a position offset from the rotation axis of the chuck table 41, thereby grinding the entire wafer 9.

[0029] Then, at the rough grinding position 44A, the wafer 9 is roughly ground by the small grindstone, and after the chuck table 41 is rotated to the finish grinding position 44B, the wafer 9 is finish ground by the large grindstone. After that, the wafer 9 is moved to the entrance / exit position 44C of the chuck table 41, and the ground surface is cleaned.

[0030] The cleaning unit 5 (see FIG. 1) is designed to remove foreign matter from the wafer 9, and is comprised of a first cleaning unit 51 for cleaning the polished surface and a second cleaning unit 52 for cleaning the back surface.

[0031] Of these, the first cleaning unit 51 is configured to spray water from an upper nozzle 51A onto the wafer 9 held by suction on the chuck table 41 at the entrance / exit position 44C, thereby removing grinding powder.

[0032] On the other hand, second cleaning section 52 is provided below second transfer path 36B, and transports wafer 9 by second transfer section 35 while it is held by suction from above, sprays water from below with nozzle 52A to remove grinding dust, and cleans the backside with brush 52B. Downstream of this, air is blown out from air outlet 52C to remove water, and wafer 9 is held by suction from the underside of turntable 52D and rotated at high speed, scattering the water by centrifugal force.

[0033] The wafers 9 from which grinding dust and water have been removed by the cleaning unit 5 are transferred from the second transfer unit 35 to the first transfer unit 31, and then their thickness is measured by the thickness measurement unit 6. The transfer path from the transfer portion of the second transfer unit 35, through the thickness measurement unit 6, to the cassette 2 is referred to as the "third transfer path 36C" (see FIG. 1).

[0034] The thickness measuring unit 6 is provided downstream along the linear direction of the second transfer path 36B, at a position across a wall surface 55 adjacent to the second cleaning unit 52 (see FIG. 1). The wall surface 55 is provided to prevent water from splashing from the cleaning unit 5, and as shown in FIG. 3, the wall surface 55 comprises a first wall surface 55A provided adjacent to the second cleaning unit 52, and a second wall surface 55B bent obliquely from the first wall surface 55A and provided near the transfer portion between the first transfer path 36A and the second transfer path 36B, and a slit 55C for passing the wafer 9 is provided on the side of the second wall surface 55B and the first wall surface 55A.

[0035] When the wafer 9 is transported along this third transport path 36C to the thickness measurement unit 6, the arms 33 of the first transport unit 31 are rotated and extended as shown by the dashed lines in Fig. 4 to transport the wafer 9 to the thickness measurement unit 6. Then, the arms 33 are raised and lowered to lift the wafer 9, and the wafer 9 is placed on a mounting table 61 provided above the slit 55C so that the thickness can be measured.

[0036] As shown in FIGS. 5 and 6 , the thickness measurement unit 6 includes an optical sensor 63A that measures the thickness of the wafer 9 placed on a mounting table 61, a contact sensor 63B that measures the thickness of the dress plate, and a movement mechanism 64 that moves the optical sensor 63A and the contact sensor 63B. The mounting table 61 is configured to support the wafer 9 and has a slit-shaped opening 62 that runs along the diameter of the wafer 9. The optical sensor 63A measures the thickness of the wafer 9 placed on the mounting table 61 along the diameter. The optical sensor 63A irradiates light from above toward the slit-shaped opening 62, measuring the thickness based on the difference in optical path length due to reflections from the front and back surfaces. The optical sensor 63A is configured to move along the slit-shaped opening 62 to measure the thickness of the wafer 9 along the diameter. If such a slit-shaped opening 62 is not provided, light is reflected by the mounting table 61, which may result in an error in the thickness. However, as in this embodiment, by irradiating light onto the slit-shaped opening 62, the thickness can be measured accurately.

[0037] After the thickness is measured by the thickness measuring unit 6 configured in this manner, the thickness is fed back to the grinding control of the grinding unit 4, and the wafer 9 for which measurement has been completed is returned to the cassette 2 using the first transport unit 31.

[0038] During such grinding operations, the grinding surface of the grinding wheel plate 43 is periodically ground using a dressing plate 8 to prepare the grinding surface. As shown in FIG. 6, the dressing plates 8 are disk-shaped with a grinding wheel in the center. Two dressing plates 8 are stored in a cassette 81, and the first conveyor 31 removes them and places them on the mounting table 61 of the thickness measuring unit 6 (as shown in FIG. 6). Then, while the dressing plate 8 is attached to the mounting table 61, a contact sensor 63B is lowered from above to measure the thickness based on the difference in height between the mounting table 61 and the plate. The measured dressing plate 8 is then transported to the chuck table 41 using the first conveyor 31 or the second conveyor 35, as shown in FIG. 1. While the dressing plate 8 is attached to the chuck table 41, the grinding wheel plate 43 below the spindle 42 is rotated to prepare the grinding surface. After the dressing operation is completed, the dressing plate 8 is stored in the cassette 81 from the chuck table 41 using the second conveyor 35 or the first conveyor 31 in the reverse order.

[0039] Next, the grinding operation, thickness measurement operation, dressing operation, etc. of the wafer 9 in the grinding apparatus 1 configured as above will be described.

[0040] 1, a cassette 2 is attached, and wafers 9 are removed one by one from the cassette 2 using a first transfer unit 31. When removing the wafers 9, the arm 33 of the first transfer unit 31 is extended and raised / lowered to support the wafers 9 on the placement unit 32, and the wafers 9 are removed from the cassette 2.

[0041] The wafer 9 taken out using this first transport section 31 is then transported along the first transport path 36A, and at the end of the first transport path 36A, the arm 33 is rotated and extended to pass the wafer 9 through the slit 55C (Figure 3) in the second wall surface section 55B and transport it to the second transport section 35.

[0042] Then, the second transfer section 35 picks up the wafer 9 placed on the placement section 32 of the first transfer section 31 from above, transfers it in a linear direction, and transfers it onto the chuck table 41 of the grinding section 4. Then, the wafer 9 is lowered and placed on the chuck table 41 and adsorbed.

[0043] The wafer 9 thus sucked onto the chuck table 41 is rotated to a rough grinding position 44A, where it is roughly ground with a small grindstone, and then to a finish grinding position 44B, where it is finish ground with a large grindstone. The wafer 9 thus finish ground is finally moved to an entrance / exit position 44C, where water is sprayed from above by a nozzle 51A constituting a first cleaning section 51.

[0044] Next, the wafer 9 cleaned by the first cleaning unit 51 is transported by the second transfer unit 35, and its backside is cleaned by the second cleaning unit 52. When cleaning the backside, water is sprayed from the nozzle 52A and the brush 52B is rotated. Then, air is discharged from the air outlet 53 to remove large amounts of water. Then, the turntable 52D is rotated at high speed to remove remaining water by centrifugal force. Then, the arm 33 of the first transfer unit 31 is extended to support the wafer 9 from below, from which the water has been removed. Note that when the wafer 9 is cleaned, splashed water is blocked by the wall surface 55.

[0045] 4, the wafer 9 transferred to the first transfer unit 31 is transferred to the thickness measurement unit 6 along the third transfer path 36C. At this time, the wafer 9 transferred from the second transfer unit 35 passes through the slit 55C, and then is raised toward the mounting table 61 provided above and placed on the mounting table 61. Note that by providing the mounting table 61 above the slit 55C in this manner, the possibility of water adhering to the wafer 9 is reduced even if water enters through the slit 55C.

[0046] In the thickness measurement unit 6 (FIGS. 5 and 6), an optical sensor 63A is moved in the radial direction relative to the wafer 9 placed on the mounting table 61 to optically measure the thickness of the entire surface along the radial direction. At this time, the thickness is measured along a slit-shaped opening 62 provided in the mounting table 61, so that the thickness can be measured over the entire area along the radial direction.

[0047] The thickness measured by the thickness measuring unit 6 is output and used to control the spindle 42 in the grinding unit 4.

[0048] Then, as shown in FIG. 3, the wafer 9 whose thickness has been measured in this manner passes through the third transfer path 36C and is accommodated in the cassette 2.

[0049] Next, the operation of preparing the grinding surface using the dressing plate 8 will be described.

[0050] When preparing the grinding surface of the grinding wheel plate 43, as shown in Figure 6, the dressing plate 8 is removed from the cassette 81 stored below the thickness measuring unit 6 using the arm 33 of the first conveying unit 31 and placed on the mounting table 61 of the thickness measuring unit 6.

[0051] Then, the contact sensor 63B is brought into contact with the dress plate 8, and the thickness is measured from the difference in thickness between the dress plate 8 and the mounting table 61.

[0052] At this time, if the dressing plate 8 is of the appropriate thickness, as shown in Figure 1, the dressing plate 8 is transported to the chuck table 41 via the first transport section 31 and the second transport section 35, where the dressing plate 8 is adsorbed onto the chuck table 41, and the dressing plate 8 and the grinding plate 43 are rotated in the same manner as when grinding the wafer 9 to prepare the grinding surface.

[0053] According to the above embodiment, in the wafer grinding device 1 for wafers 9, the device 1 comprises a cassette 2 for storing wafers 9, a transport unit 3 consisting of a first transport unit 31 and a second transport unit 35 for transporting the wafers 9 removed from the cassette 2, a grinding unit 4 for placing and grinding the wafers 9 transported by the transport unit 3, and a cleaning unit 5 provided between the cassette 2 and the grinding unit 4 for cleaning the wafers 9 ground by the grinding unit 4. In this manner, a thickness measuring unit 6 for measuring the thickness of the wafers 9 is provided in the transport path between the cleaning unit 5 and the cassette 2. This prevents grinding powder and the like from the grinding unit 4 from adhering to the wafers 9, and makes it possible to accurately measure the thickness of the wafers 9.

[0054] The present invention is not limited to the above-described embodiment, but can be implemented in various forms.

[0055] For example, in the above embodiment, both surfaces of the wafer 9 are cleaned before the thickness is measured, but it is also possible to clean only the ground surface before measuring the thickness.

[0056] Furthermore, in the above embodiment, when performing thickness measurement, the wafer 9 or the dress plate 8 is placed on the mounting table 61 having a slit-shaped opening 62, and the thickness along the entire radial direction is measured, but the thickness may be measured by other methods.

[0057] Furthermore, in the above embodiment, the thickness measuring unit 6 is provided at a position where the movement directions of the first conveying unit 31 and the second conveying unit 35 intersect, but the thickness measuring unit 6 may be provided at a location other than this. In such a case, it is preferable to provide the thickness measuring unit 6 at a position covered by the wall surface 55 so as to prevent scattering of grinding powder and the like from the grinding unit 4. [Explanation of symbols]

[0058] 1. Grinding equipment 2 cassettes 3. Conveyor section 31 First conveying section 35 Second conveying section 36A First transport path 36B Second transport path 36C Third transport route 4. Grinding section 41 Chuck table 5. Cleaning section 51 First cleaning section 52 Second cleaning section 5. Wall 55A...First wall 55B...Second wall 55C···Slit 6. Thickness measurement unit 63A···Optical sensor 63B...Contact sensor 8. Dressing plate

Claims

1. a cassette for accommodating wafers; a transfer unit that transfers the wafer taken out from the cassette; a grinding unit that places and grinds the wafer transferred by the transfer unit; a cleaning unit provided between the cassette and the grinding unit for cleaning the wafers ground by the grinding unit; A wafer grinding apparatus comprising: A wafer grinding apparatus characterized in that a thickness measuring unit for measuring the thickness of the wafer is provided in a transfer path between the cleaning unit and the cassette.

2. 2. The wafer grinding apparatus according to claim 1, wherein a wall surface is provided between the cleaning section and the thickness measuring section on the transfer path.

3. a first wall surface portion is provided between the cleaning portion and the thickness measuring portion in the conveying path; a second wall portion having a slit for passing a wafer therethrough is provided on a side of the first wall portion; 2. The wafer grinding apparatus according to claim 1, wherein the wafer is transported from the cleaning section to the thickness measuring section through the slit in the second wall surface section.

4. the transfer unit includes a first transfer unit that removes the wafer from the cassette; a second transfer unit that receives the wafer transferred by the first transfer unit, transfers the wafer to the grinding unit, and passes the ground wafer through a cleaning position; It is provided with 2. The wafer grinding apparatus according to claim 1, wherein the wafer cleaned in the cleaning section is transported to the thickness measuring section by using the first transport section.

Images