TWI889981B - Resin coating method and resin coating device - Google Patents

Abstract

[Question] Appropriately measure wafer thickness while suppressing variations in the thickness of the resin layer covering the front surface of the wafer, regardless of wafer type. [Solution] A temporary stage holding the wafer, along with a first and second measuring instruments, are moved relative to each other in a direction parallel to the holding surface of the temporary stage. In this case, the coordinates of a point on the outer periphery of the wafer are detected by referring to the measurement results of the first or second measuring instruments. The thickness of the wafer is then measured at a predetermined distance from this point, near the center of the wafer. This predetermined distance is set according to the wafer type, enabling appropriate wafer thickness measurement while suppressing variations in the thickness of the resin layer covering the front surface of the wafer.

Description

Resin coating method and resin coating device

The present invention relates to a resin coating method and a resin coating device for coating the front surface of a circular wafer with resin.

Chips containing devices such as ICs (Integrated Circuits) and LSIs (Large Scale Integration) are essential components of various electronic devices, including mobile phones and personal computers. These chips are manufactured by forming a large number of devices on the front surface of a circular wafer made of semiconductor material, and then dividing the wafer into regions containing individual devices.

In the wafer manufacturing process, the back side of the wafer is often ground to thin it before it is divided, in order to minimize the size of the wafer being manufactured. This thinning is generally performed using a grinding device with a worktable and a grinding wheel. The worktable attracts and holds the front side of the wafer, while the grinding wheel grinds the back side of the wafer.

The front surface of the wafer has uneven shapes due to the presence of bumps, which form the electrode pattern of the device and the substrate used to assemble the device onto a printed wiring board. Furthermore, grinding the back surface of a wafer with such uneven shapes while the worktable directly holds the front surface directly can locally apply a large load to the wafer. Consequently, this can cause damage to the electrode pattern and bumps.

With this in mind, before grinding the back side of a wafer, a common method, for example, involves forming a flat resin layer on the front side of the wafer (the side facing away from the wafer) using the following procedure. Specifically, the back side of the wafer is first held by a holding plate. Next, liquid resin is applied to a worktable facing the holding plate, with the wafer and the holding plate interposed. The holding plate and the worktable are then brought closer together until the front side of the wafer contacts the liquid resin. The liquid resin is then cured.

This allows the front side of the wafer to be coated with a flat resin layer. Furthermore, when grinding the back side of the wafer while the worktable holds the front side of the wafer under suction through this resin layer, there is no localized load applied to the wafer. This prevents damage to the electrode pattern and bumps. Furthermore, the thickness of the resin layer is determined by the distance between the holding plate and the worktable when the liquid resin is applied to the front side of the wafer.

However, even if multiple wafers are manufactured using the same manufacturing steps to achieve the desired thickness, there is still a possibility of variations in thickness among these wafers. Therefore, if the distance between the retaining plate and the worktable is not adjusted according to the wafer thickness, as described above, when the front surfaces of each of the multiple wafers are coated with a resin layer, there is a possibility of variations in the thickness of this resin layer. Furthermore, in this case, there is a concern that the electrode pattern and bumps on some wafers may be damaged by grinding the back side.

With this in mind, a proposed method involves measuring the wafer thickness and then determining the distance between the retaining plate and the worktable when coating the front surface of the wafer with liquid resin based on the measured thickness (see, for example, Patent Document 1). This method can minimize variations in the thickness of the resin layer applied to the front surface of multiple wafers. Prior Art Patent Document

Patent Document 1: Japanese Patent Application Publication No. 2021-19160

Invention problem to be solved

As mentioned above, the front surface of a wafer has uneven shapes due to the presence of electrode patterns and bumps. In order to cover the front surface of a wafer with such uneven shapes with a resin layer of a predetermined thickness, it is necessary to measure the thickness of the wafer in areas where the electrode patterns and bumps are not present before forming the resin layer.

Such areas typically exist near the perimeter of the wafer (e.g., within a few millimeters of the perimeter). Furthermore, chamfers are typically formed near the perimeter of the wafer to prevent crack formation. In other words, the wafer becomes thinner as it approaches the perimeter.

Therefore, the thickness of the wafer before the resin layer is formed should be measured in a region near the center of the wafer where the electrode pattern and bumps are not present. However, the size of this region (e.g., the width along the wafer's radial direction) varies depending on the type of wafer.

In light of this, an object of the present invention is to provide a resin coating method and apparatus that can appropriately measure wafer thickness while suppressing variations in the thickness of the resin layer on the front surface of the coated wafer, regardless of the type of wafer. Means for Solving the Problem

According to one aspect of the present invention, a resin coating method is provided for coating the front surface of a circular wafer with a resin layer. The resin coating method comprises the following steps: a thickness measuring step of measuring the thickness of the wafer; a holding step of holding the back surface of the wafer with a holding plate; a resin supplying step of supplying liquid resin to a worktable facing the holding plate; an approaching step of bringing the holding plate and the worktable closer together so that the distance between the holding plate and the worktable becomes a distance determined by the thickness of the wafer measured in the thickness measuring step; and a curing step of curing the liquid resin. The thickness measuring step comprises: A temporary table holding step is performed by using a temporary table having a holding surface and being rotatable about a straight line passing through the center of the holding surface and perpendicular to the holding surface as a rotation axis to hold the wafer whose outer periphery is positioned outside the holding surface in a planar viewing angle; The detection step comprises moving the temporary stage and the first and second measuring tools, which face each other in a direction perpendicular to the holding surface, relative to each other in a direction parallel to the holding surface so that a point on the outer periphery passes through a measurement position between the first and second measuring tools. The first measuring tool measures the distance between the first measuring tool and the wafer, or the second measuring tool measures the distance between the second measuring tool and the wafer, thereby obtaining a measurement result, and detecting the coordinates of the point with reference to the measurement result. A measuring step comprises: positioning a point on the wafer, which is located outside the holding surface and a predetermined distance closer to the center of the wafer than the point in a planar view, at the measurement position; measuring the distance between the first measuring tool and the wafer using the first measuring tool, and measuring the distance between the second measuring tool and the wafer using the second measuring tool; and A thickness calculation step comprises: calculating the thickness of the wafer by subtracting the following distances from the distance between the first measuring tool and the wafer: the distance between the first measuring tool and the wafer measured by the first measuring tool with the point positioned at the measurement position; and the distance between the second measuring tool and the wafer measured by the second measuring tool.

Preferably, the resin coating method of the present invention further includes the following steps: a center calculation step of calculating the center of the wafer based on the coordinates of at least three points on the outer periphery detected in the detection step; and an adjustment step of adjusting the center point of a suction pad to a position corresponding to the center of the wafer when the wafer is removed from the temporary stage by a transport unit having a suction pad for attracting the wafer and transporting the wafer.

According to another aspect of the present invention, a resin coating device is provided for coating the front surface of a circular wafer with a resin layer. The resin coating device comprises: a thickness measuring unit for measuring the thickness of the wafer; a resin coating unit for coating the front surface of the wafer with the resin layer; and a control unit for controlling the thickness measuring unit and the resin coating unit. The thickness measuring unit comprises: a temporary table having a holding surface for holding the wafer and rotatable about a straight line passing through the center of the holding surface and perpendicular to the holding surface as a rotation axis; a first measuring device and a second measuring device facing each other in a direction perpendicular to the holding surface; and a first moving mechanism for moving the temporary table, the first measuring device, and the second measuring device relative to each other in a direction parallel to the holding surface. The first measuring device measures the distance between the first measuring device and the wafer positioned at a measurement position between the first measuring device and the second measuring device. The second measuring device measures the distance between the second measuring device and the wafer positioned at the measurement position. The resin coating unit comprises: a holding plate for holding the wafer; a workbench facing the holding plate; a resin supply source for supplying liquid resin to the workbench; a second moving mechanism for adjusting the distance between the holding plate and the workbench; and a resin hardener for hardening the liquid resin. The control unit comprises: a driving section that drives the first moving mechanism so that a point on the outer periphery of the wafer disposed outside the holding surface in a plane viewing angle passes through the measurement position, and drives the second moving mechanism so that the distance between the holding plate holding the wafer and the worktable supplied with the liquid resin becomes a distance determined according to the thickness of the wafer; and a detection section that detects the point on the outer periphery by referring to the measurement result of the first measuring device or the second measuring device when the point on the outer periphery passes through the measurement position. The thickness calculation unit calculates the thickness of the wafer by subtracting the following distances from the distance between the first measuring device and the wafer measured by the first measuring device and the distance between the second measuring device and the wafer measured by the second measuring device, with a point on the wafer located a predetermined distance from the point near the center of the wafer and outside the holding surface when viewed from a plane, from the distance between the first measuring device and the second measuring device positioned at the measurement position.

Preferably, the resin coating apparatus of the present invention further comprises: a transport unit having an attraction pad for attracting the wafer and transporting the wafer; the control unit further comprising: a center calculation unit for calculating the center of the wafer based on the coordinates of at least three points on the outer periphery detected by the detection unit; and an adjustment unit for adjusting the center point of the attraction pad to a position corresponding to the center of the wafer when the transport unit is about to remove the wafer from the temporary stage. Effects of the Invention

In the present invention, a temporary table holding a wafer and a first and second measuring device can be moved relative to each other in a direction parallel to the holding surface of the temporary table. Therefore, the present invention can detect the coordinates of a point on the outer periphery of the wafer by referring to the measurement results of the first or second measuring device, and then measure the wafer thickness at a predetermined distance from this point to the center of the wafer. Thus, by setting the predetermined distance according to the type of wafer, the present invention can appropriately measure the thickness of the wafer while minimizing variations in the thickness of the resin layer covering the front surface of the wafer.

Form used to implement the invention

The embodiments of the present invention are described with reference to the accompanying drawings. FIG1(A) schematically shows a top view of an example wafer, and FIG1(B) schematically shows a cross-sectional view of an example wafer. Wafer 11 has a substantially parallel front surface 11a and back surface 11b and is made of, for example, Si (silicon), SiC (silicon carbide), GaN (gallium nitride), GaAs (gallium arsenide), or other semiconductor materials.

The periphery of wafer 11 is chamfered. That is, side surface 11c of wafer 11 is curved outward to form a convex shape. Furthermore, a plurality of intersecting predetermined dividing lines are defined on front surface 11a of wafer 11. Devices such as ICs or LSIs are formed in each of the plurality of regions 13 demarcated by these predetermined dividing lines.

Each device is also provided with a bump 15 for electrical connection to that device. When wafer 11 is sliced to produce device chips, bumps 15 function as electrodes, electrically connecting the device to the printed wiring board (PCB) on which the chip is mounted. Bumps 15 are made of a metal material such as Au (gold), Ag (silver), Cu (copper), or Al (aluminum).

FIG2 is a perspective view schematically showing an example of a cassette for accommodating wafers 11. The cassette 2 shown in FIG2 has a flat top plate 4. This top plate 4 has the following shape: A pair of adjacent corners of the four corners of the rectangular flat plate are chamfered, while the remaining pair of corners are left unchamfered. Furthermore, the upper end of a side wall (not shown) is fixed to the lower side of the end (rear end) between the pair of chamfered portions of the top plate 4. The side wall extends in a direction perpendicular to the top plate 4 (in the height direction).

Furthermore, the upper ends of side walls 6a and 6b extending in the height direction are fixed to the lower sides of each of the two ends (the left and right ends) of the top plate 4 located between the chamfered portion and the unchamfered corner. On the other hand, no side wall extending in the height direction is fixed to the lower side of the end (the front end) located between the opposite unchamfered corners of the top plate 4. In other words, the lower side of the front end of the top plate 4 is open.

On the inner surfaces of sidewalls 6a and 6b, a plurality of wafer-supporting grooves 8 are provided at predetermined intervals in the height direction and in a direction perpendicular to the height direction. Specifically, each of the plurality of wafer-supporting grooves 8 provided on the inner surface of sidewall 6a is arranged to face any of the plurality of wafer-supporting grooves 8 provided on the inner surface of sidewall 6b.

Furthermore, the cross-section of the wafer support trench 8, measured in a plane perpendicular to the top plate 4 and the sidewalls 6a and 6b, is generally rectangular. In other words, the wafer support trench 8 has a pair of inner side surfaces generally perpendicular to the height direction, and a bottom surface generally parallel to the height direction. Furthermore, within the cassette 2, the wafer 11 is accommodated such that it is positioned on the inner side of the wafer support trench 8, farther from the top plate 4.

Furthermore, the lower portion of sidewall 6a and the lower portion of sidewall 6b are connected via a slender, plate-shaped connecting member 10. Furthermore, there is no limit to the number of wafer-supporting grooves 8 provided on the inner surface of sidewall 6a and the inner surface of sidewall 6b. For example, the cassette 2 may be provided with a number of wafer-supporting grooves 8 corresponding to a batch of wafers 11 (approximately 25 wafers).

FIG3 is a block diagram schematically illustrating an example of a resin coating apparatus for coating the front surface 11a of a wafer 11 with a resin layer. Specifically, the resin coating apparatus 12 shown in FIG3 removes wafers 11 from a cassette 2, coats the front surface 11a with a resin layer, and then carries the wafers 11, whose front surface 11a has been coated with the resin layer, back into the cassette 2.

Furthermore, the numbered arrows shown in FIG3 indicate the movement of wafer 11 when the front surface 11a of wafer 11 is coated with a resin layer. Specifically, when the front surface 11a of wafer 11 is coated with a resin layer, wafer 11 is moved in ascending order of the numbers indicated by the arrows shown in FIG3 . Furthermore, resin coating apparatus 12 includes a cassette support table (not shown) on which cassette 2 is placed.

The resin coating device 12 also includes a transfer unit 14 for unloading wafers 11 from a cassette 2 placed on the cassette support table and loading wafers 11 into the cassette 2. FIG4 is a perspective view schematically showing an example of the transfer unit 14. The transfer unit 14 includes a cylindrical transfer base 16 extending in the height direction.

Inside the transport base 16, an actuator (not shown) such as an air cylinder is installed. This actuator has a piston rod that can move vertically and rotate around a vertical axis. An opening is provided on the top surface of the transport base 16 for the piston rod to pass through. Furthermore, a transport arm 18 is connected to the upper end of this piston rod.

The transport arm 18 is a robotic arm with multiple joints. Specifically, the transport arm 18 includes a plate-shaped first arm portion 18a extending perpendicular to its height. The lower side of one end of the first arm portion 18a is connected to the upper end of the piston rod so that it moves and rotates with the piston rod. Furthermore, the lower side of a cylindrical first joint portion (not shown) is connected to the upper side of the other end.

A plate-shaped second arm portion 18b extending perpendicularly to the height direction is connected to the upper side of the first joint portion. The lower side of one end of the second arm portion 18b is connected to the upper side of the other end of the first arm portion 18a via the first joint portion so as to be rotatable about a rotation axis extending along the height direction. Furthermore, the lower side of the cylindrical second joint portion 18c is connected to the upper side of the other end of the second arm portion 18b.

A third arm 18d extending perpendicularly to the height direction is connected to the upper side of the second joint 18c. The lower side of one end of the third arm 18d is connected to the upper side of the other end of the second arm 18b via the second joint 18c so as to be rotatable about a rotation axis along the height direction.

Furthermore, a non-contact sensor 20 is provided on one end of the upper surface of the third arm 18d. The non-contact sensor 20 detects structures located in the direction from the other end toward the one end of the third arm 18d, as viewed from the third arm 18d. The non-contact sensor 20 is, for example, a photosensor having a light projector and a light receiver. The light projector projects light (e.g., a laser beam) in that direction, and the light receiver receives light reflected by the structure.

Furthermore, a motor (not shown) is installed within the third arm 18d. This motor rotates a main shaft 18e, which is rotatable in a direction perpendicular to the height direction. This main shaft 18e passes through an opening provided in the side surface of the other end of the third arm 18d, with its tip exposed to the outside. Furthermore, the tip of the main shaft 18e is connected to the rectangular base of the suction pad 22 via a plate-like connecting portion 18f.

The suction pad 22 also has an elliptical plate-shaped portion integral with its base end. Specifically, this portion is shaped so that the major axis of the ellipse is parallel to the main axis 18e, and a linear notch is provided in this portion extending from its center toward the tip. Furthermore, a plurality of suction holes (not shown) are provided on one surface of the elliptical plate-shaped portion of the suction pad 22.

This suction hole is connected to a suction source such as an ejector (not shown) through a flow path and a valve that controls the flow of gas, etc., provided inside the suction pad 22. Furthermore, if the suction source is operated with the valve open, negative pressure is generated in the space near the suction hole.

Therefore, one surface of the elliptical plate-shaped portion of the suction pad 22 functions as a holding surface for attracting and holding the wafer 11. Furthermore, in the transport unit 14, by rotating the spindle 18e while the wafer 11 is being attracted and held by the holding surface of the suction pad 22, the wafer 11 can be flipped upside down. In other words, the wafer 11 can be held on either the upper or lower side of the suction pad 22.

Furthermore, the transport base 16 is connected to a transport unit moving mechanism (not shown) disposed below it. This transport unit moving mechanism includes, for example, a ball screw and a motor. Furthermore, when this motor is activated, the transport unit 14 moves horizontally.

When the transport unit 14 removes a wafer 11 from a cassette 2, the transport unit's moving mechanism is first activated to position the transport unit 14 near the cassette support platform where the cassette 2 is placed. Next, to detect the cassette level (the height of the wafer support trench 8) of the cassette 2 containing the wafer 11, the actuator and transport arm 18 housed on the transport base 16 are activated, while the non-contact sensor 20 is also activated.

Next, the actuator and transfer arm 18, housed on the transfer base 16, are operated so that the center point of the suction pad 22 approaches a position slightly higher or lower than the detected cassette level (the height of the wafer support groove 8) of the cassette 2 and corresponding to the center between the side walls 6a and 6b of the cassette 2. The center point of the suction pad 22 is assumed to be the point where the center of the wafer 11 is located when the holding surface of the suction pad 22 attracts and holds the wafer 11.

Next, the suction source connected to the suction holes provided on the holding surface of the suction pad 22 is operated. As a result, the wafer 11 is sucked and held by the holding surface of the suction pad 22. Next, the actuator and the transfer arm 18 are further operated to remove the wafer 11 from the cassette 2.

The wafer 11 removed from the cassette 2 in this manner can be carried by the transport unit 14 into, for example, a thickness measurement unit 24 for measuring the thickness of the wafer 11. FIG5 is a perspective view schematically showing an example of the thickness measurement unit 24. Furthermore, the X-axis direction (front-back direction) and the Y-axis direction (left-right direction) shown in FIG5 are mutually perpendicular directions on a horizontal plane, and the Z-axis direction (height direction) is a direction perpendicular to the X-axis and Y-axis directions (a vertical direction).

The thickness measuring unit 24 has a gate-shaped first support structure 26. The first support structure 26 includes a pair of flat vertical portions 26a and 26b extending in the Z-axis direction, and a flat overlapping portion 26c extending in the Y-axis direction and connecting the upper ends of the pair of vertical portions 26a and 26b.

A Y-axis movement mechanism (first movement mechanism) 28 is provided on the front surface (front face) of the bridging portion 26c. This Y-axis movement mechanism 28 includes a pair of guide rails 30 fixed to the front surface of the bridging portion 26c and extending horizontally. Furthermore, an L-shaped movement member 32 is provided on the front surface (front face) of the pair of guide rails 30.

This moving member 32 comprises a vertical portion 32a extending in the Z-axis direction, and a table support portion 32b extending forward from the lower end of the vertical portion 32a along the X-axis. Furthermore, the rear surface (back side) of the vertical portion 32a is slidably connected to the front surface (front side) of the pair of guide rails 30.

A screw shaft 34 extending along the Y-axis is disposed between the pair of guide rails 30. A motor 36 is connected to the end of the screw shaft 34 on the side of the vertically disposed portion 26b, which rotates the screw shaft 34. Furthermore, a nut portion (not shown) that houses balls is provided on the surface of the screw shaft 34 where the spiral groove is formed, forming a ball screw. The balls roll on the surface of the rotating screw shaft 34.

That is, when the screw shaft 34 rotates, the balls circulate within the nut, causing the nut to move along the Y-axis. Furthermore, the nut is fixed to the rear surface (back side) of the moving member 32. Therefore, simply rotating the screw shaft 34 with the motor 36 causes the moving member 32 to move along the Y-axis along with the nut.

A cylindrical θ table 38 is provided on the upper surface of the table support portion 32b of the moving member 32. This θ table 38 is connected to the table support portion 32b so as to be rotatable along a straight line in the Z-axis direction as its rotation axis, and the lower portion of a disk-shaped temporary table 40 is fixed to its upper portion.

The temporary workbench 40 comprises a disc-shaped frame 42 made of a metal material such as stainless steel. This frame 42 has a disc-shaped bottom wall and an annular sidewall extending upward from the outer periphery of this bottom wall. The bottom wall and sidewalls define a recessed portion on the upper surface of the frame 42, into which a disc-shaped perforated plate 44 made of ceramic or other materials is secured.

The porous plate 44 has an upper surface parallel to the X-axis and the Y-axis. The lower surface of the porous plate 44 is connected to a suction source (not shown) such as an ejector via the frame 42, the θ table 38, a suction passage (not shown) formed within the table support 32b, and piping and valves connected to the table support 32b.

Furthermore, when the valve is opened while the suction source is activated, negative pressure is generated in the space near the upper surface of the porous plate 44. Therefore, the upper surface of the porous plate 44 functions as the holding surface of the temporary table 40, which holds the wafer 11. Furthermore, the diameter of this circular holding surface (the outer diameter of the frame 42) is designed to be shorter than the diameter of the wafer 11.

Furthermore, the θ table 38 is connected to a rotational drive source (not shown) such as a motor. When this rotational drive source is activated, the θ table 38 and the temporary table 40 rotate about a straight line passing through the center of the holding surface of the temporary table 40 and parallel to the Z axis.

A second supporting structure 46 is provided in front of the vertical portion 26a. This second supporting structure 46 comprises a vertical portion 46a arranged parallel to the temporary table 40 in the Y-axis direction; a pair of overlapping portions 46b and 46c extending from the side of the vertical portion 46a on the temporary table 40 side at different heights so as to face the temporary table 40; a lower protrusion 46d protruding downward from the front end of the overlapping portion 46b; and an upper protrusion 46e protruding upward from the front end of the overlapping portion 46c.

Furthermore, the lower surface of the lower protrusion 46d faces the upper surface of the upper protrusion 46e. Furthermore, the lower surface of the lower protrusion 46d is located at a higher position than the holding surface of the temporary table 40. Furthermore, the upper surface of the upper protrusion 46e is located at a lower position than the holding surface of the temporary table 40.

Furthermore, a first measuring device 48a is built into the lower protrusion 46d, and a second measuring device 48b is built into the upper protrusion 46e. The first measuring device 48a and the second measuring device 48b are arranged to face each other in the Z-axis direction.

The first measuring device 48a includes, for example, a light projecting unit that projects a laser beam downward and a light receiving unit that receives the laser beam incident from below. Therefore, when a portion of the wafer 11, held on the temporary table 40, is positioned at a measurement position between the first measuring device 48a and the second measuring device 48b, a laser beam is projected from the light projecting unit of the first measuring device 48a. This laser beam is reflected by the upper surface of the wafer 11 and received by the light receiving unit of the first measuring device 48a. Furthermore, the first measuring device 48a measures the distance to the wafer 11 (the distance between the first measuring device 48a and the wafer 11) based on, for example, the phase difference between the laser beam projected from the light projecting unit and the laser beam received by the light receiving unit.

Similarly, the second measuring device 48b includes, for example, a light projecting unit that projects a laser beam upward and a light receiving unit that receives the laser beam incident from above. Therefore, when a portion of the wafer 11 held on the temporary table 40 is positioned at the measurement position between the first measuring device 48a and the second measuring device 48b, a laser beam is projected from the light projecting unit of the second measuring device 48b. This laser beam is reflected by the lower surface of the wafer 11 and received by the light receiving unit of the second measuring device 48b. Furthermore, the second measuring device 48b measures the distance to the wafer 11 (the distance between the second measuring device 48b and the wafer 11) based on, for example, the phase difference between the laser beam projected from the light projecting unit and the laser beam received by the light receiving unit.

When measuring the distance between each of the first and second measuring devices 48 a and 48 b and the wafer 11 , the transport unit moving mechanism is first operated to position the transport unit 14 transporting the wafer 11 near the thickness measuring unit 24 .

Next, the Y-axis moving mechanism 28 is operated to be positioned at a position where the wafer 11 can be moved to the holding surface of the temporary table 40 by the transfer unit 14 (for example, a position away from the first measuring device 48a and the second measuring device 48b).

Next, the motor built into the third arm 18 d rotates the spindle 18 e so that the wafer 11 faces downward, that is, the wafer 11 is attracted and held by the lower side of the suction pad 22 .

Next, the actuator and the transport arm 18 accommodated on the transport base 16 are operated to bring the center point of the suction pad 22 close to the center of the holding surface of the temporary table 40. Next, the operation of the suction source connected to the suction holes provided on the holding surface of the suction pad 22 is stopped.

Thus, the wafer 11 is placed on the holding surface of the temporary table 40. Furthermore, the diameter of this holding surface (the outer diameter of the frame 42) is shorter than the diameter of the wafer 11. Therefore, the outer periphery of the wafer 11 is arranged outside the holding surface of the temporary table 40.

Next, after the suction source connected to the lower surface of the porous plate 44 via a valve or the like is activated, the valve is opened. This allows the central area of the wafer 11 to be held by suction on the holding surface of the temporary table 40.

Next, the Y-axis moving mechanism 28 is operated to position the portion of the wafer 11 outside the holding surface of the temporary table 40 at a measurement position between the first and second measuring devices 48a and 48b (between the lower surface of the lower protrusion 46d and the upper surface of the upper protrusion 46e).

Next, the first measuring device 48 a is operated to measure the distance between the first measuring device 48 a and the wafer 11 , and the second measuring device 48 b is operated to measure the distance between the second measuring device 48 b and the wafer 11 .

The wafer 11, whose distance from each of the first and second measuring devices 48a, 48b has been measured in this manner, is then unloaded from the thickness measurement unit 24 by the transport unit 14 and brought into the resin coating unit 50, where the front surface 11a of the wafer 11 is coated with a resin layer, for example. FIG6 is a perspective view schematically showing an example of the resin coating unit 50.

Resin-coated unit 50 comprises a rectangular base 52 with an internal space. A workbench 54 with a substantially flat top surface is positioned above base 52 to enclose the internal space. Workbench 54 is constructed from a UV-transmissive material such as borosilicate glass, quartz glass, or translucent alumina.

Furthermore, liquid UV-curing resin can be supplied to the upper surface of the workbench 54 from a resin supply source (not shown). Furthermore, the UV-curing resin can be supplied to the workbench 54 by placing a sheet on the upper surface of the workbench 54 using a sheet supply unit (not shown). In other words, the UV-curing resin can be supplied to the workbench 54 through the sheet. This can prevent contamination of the workbench 54 by the UV-curing resin.

The sheet supply unit pulls the sheet from a roll of flat sheets, for example, and cuts the sheet into predetermined lengths before conveying the cut sheets to a workbench. The sheet is made of a UV-transmissive material, such as polyolefin or polyethylene terephthalate.

Furthermore, a resin curing device 56 is installed within the interior of the base 52 to cure the UV-curable resin supplied to the workbench 54. The resin curing device 56 comprises a light source 58 for emitting UV light; a light gate 60, located between the workbench 54 and the light source 58, to block the UV light from the light source 58; and a filter 62 to block light of wavelengths not necessary for curing the UV-curable resin.

Furthermore, to suppress the temperature rise within the base 52, an exhaust pipe 64 connected to an exhaust pump (not shown) is provided on the side wall of the base 52. Specifically, in the resin-coated unit 50, there is a concern that the temperature within the base 52 may rise due to the ultraviolet irradiation from the light source 58.

In this case, there is a concern that the workbench 54 may be deformed, causing the flatness of the upper surface (supporting surface) to decrease. Therefore, in the resin-coated unit 50, the internal space of the base 52 can be exhausted through the exhaust pipe 64 to suppress the temperature rise of the internal space of the base 52.

Furthermore, a support structure 66 is provided on the base 52. This support structure 66 includes a vertical portion 66a extending upward from the base 52, and an eave portion 66b extending from the upper end of the vertical portion 66a and positioned above the workbench 54. Furthermore, a lifting mechanism (second moving mechanism) 68 is provided in the center of the eave portion 66b.

The lifting mechanism 68 includes a main actuator 70 disposed perpendicularly to the central portion of the eave 66b and extending through the eave 66b, and a plurality of sub-actuators 72 disposed approximately parallel to the main actuator 70 and extending through the eave 66b. The sub-actuators 72 are arranged at approximately equal intervals to surround the main actuator 70.

Each of the main actuator 70 and the plurality of sub-actuators 72 has a piston rod (not shown) that can move in the height direction. Furthermore, a disc-shaped retaining plate 74 is fixed to the lower end of these piston rods. This retaining plate 74 has a porous plate (not shown) with its lower surface exposed at the bottom.

The upper surface of the porous plate is connected to a suction source (not shown) such as an ejector through a main actuator 70, a suction path (not shown) formed inside the support structure 66 and the base 52, and piping and valves connected to the base 52.

Furthermore, if the valve is opened while the suction source is activated, a negative pressure is generated in the space near the lower surface of the porous plate (the lower surface of the holding plate 74). Therefore, the lower surface of the holding plate 74 functions as a holding surface for attracting and holding the wafer 11.

In the resin coating unit 50, when coating the front surface 11a of the wafer 11 with a resin layer, the transport unit moving mechanism is first activated to move the transport unit 14, which transports the wafer 11, to the vicinity of the resin coating unit 50. Next, the motor built into the third arm 18d rotates the spindle 18e, so that the back surface 11b of the wafer 11 faces upward, that is, the front surface 11a of the wafer 11 is attracted and held by the upper side of the suction pad 22.

Next, the actuator and transfer arm 18, housed on the transfer base 16, are activated to bring the center point of the suction pad 22 closer to the center of the holding surface of the holding plate 74. Next, the suction source connected to the suction holes provided on the holding surface of the suction pad 22 is stopped. Next, the suction source connected to the upper surface of the porous plate of the holding plate 74 is activated. This causes the back surface 11b of the wafer 11 to be held by the holding surface of the holding plate 74.

Next, the actuator and transport arm 18, housed in the transport base 16, are actuated to retract the suction pad 22 from between the holding plate 74 and the worktable 54. Liquid UV-curing resin is then applied to the upper surface of the worktable 54. Alternatively, the UV-curing resin can be applied to the upper surface of the worktable 54 after the sheet is placed on the upper surface.

Next, the lifting mechanism 68 is actuated to lower the holding plate 74, allowing the front surface 11a of the wafer 11 to contact the UV-curable resin. Next, the shutter 60 is opened. Ultraviolet light from the light source 58 is then applied to the UV-curable resin via the filter 62 and the worktable 54. This causes the UV-curable resin contacting the front surface 11a of the wafer 11 to cure. As a result, the front surface 11a of the wafer 11 is coated with a resin layer.

In this way, the wafer 11 whose front side 11a is covered with the resin layer is moved out of the resin coating unit 50 by the conveying unit 14 and moved into the cassette 2, so as to be accommodated in the same cassette level (the height of the wafer support groove 8) as the cassette level of the cassette 2 that accommodated the wafer 11 before being covered with the resin layer.

Furthermore, the operations of the transport unit 14, thickness measuring unit 24, and resin coating unit 50 are controlled by a control unit 76 built into the resin coating device 12. FIG7 is a block diagram showing an example of the control unit 76.

The control unit 76 shown in FIG7 includes, for example, a processing unit 78 and a memory unit 80. The processing unit 78 generates signals for controlling the operations of the transport unit 14, the thickness measurement unit 24, and the resin coating unit 50. The memory unit 80 stores various information (data, programs, etc.) used by the processing unit 78. For example, the memory unit 80 stores information such as the distance between the first measuring device 48a and the second measuring device 48b included in the thickness measurement unit 24, and the predetermined thickness of the resin layer covering the front surface 11a of the wafer 11.

The functions of processing unit 78 can be implemented by a CPU (Central Processing Unit) or the like that reads and executes the program stored in memory unit 80. Furthermore, the functions of memory unit 80 can be implemented by at least one of semiconductor memory such as DRAM (Dynamic Random Access Memory), SRAM (Static Random Access Memory), and NAND flash memory, and magnetic storage devices such as HDD (Hard Disk Drive).

The processing unit 78 includes a driving unit 82, a detecting unit 84, a thickness calculating unit 86, a center calculating unit 88, and an adjusting unit 90. In the processing unit 78, these functional units independently perform processing in a non-simultaneous or simultaneous manner.

The drive unit 82 controls the transport unit moving mechanism that moves the transport unit 14, the Y-axis moving mechanism (first moving mechanism) 28 that moves the temporary stage 40 of the thickness measurement unit 24, and the lifting mechanism (second moving mechanism) 68 that raises and lowers the holding plate 74 of the resin coating unit 50. For example, the drive unit 82 controls the lifting mechanism 68 so that the gap between the holding surface of the holding plate 74 that attracts and holds the wafer 11 and the upper surface of the table 54 to which the UV curing resin is applied is a predetermined gap.

The detection unit 84 detects the coordinates of a point on the outer periphery of the wafer 11 on a plane parallel to the X-axis and Y-axis directions (XY coordinate plane) by referring to the measurement results of the first measuring device 48a or the second measuring device 48b of the thickness measurement unit 24. For example, the detection unit 84 detects the coordinates of a point on the outer periphery of the wafer 11 on the XY coordinate plane where the distance to the wafer 11 cannot be measured by the first measuring device 48a or the second measuring device 48b.

Specifically, each of the first and second measuring devices 48a, 48b projects a laser beam toward the wafer 11 and receives the laser beam reflected from the wafer 11. When the laser beam is irradiated near the chamfered outer periphery of the wafer 11, it is reflected in a direction different from that toward each of the first and second measuring devices 48a, 48b.

Furthermore, in this case, it becomes impossible for each of the first measuring device 48a and the second measuring device 48b to measure the distance to the wafer 11. On the other hand, when the laser beam is projected onto the flat front surface 11a or back surface 11b of the wafer 11, it becomes possible for each of the first measuring device 48a and the second measuring device 48b to measure the distance to the wafer 11.

Therefore, by referring to the measurement results of the first measuring device 48a or the second measuring device 48b when the temporary stage 40 is moved so that the point on the outer periphery of the wafer 11 passes through the measurement position, the coordinates of the point on the outer periphery of the wafer 11 on the XY coordinate plane can be detected. For example, the coordinates of the point on the outer periphery of the wafer 11 that cannot be measured and that are adjacent to the coordinates on the XY coordinate plane where the distance to the wafer 11 can be measured can be detected as the coordinates of the point on the outer periphery of the wafer 11.

The thickness calculator 86 calculates the thickness of the wafer 11 based on the measurement results of the first and second measuring devices 48a, 48b. For example, the thickness calculator 86 measures the thickness of the wafer 11 by subtracting the distance between the first measuring device 48a and the wafer 11 measured by the first measuring device 48a and the distance between the second measuring device 48b and the wafer 11 measured by the second measuring device 48b from the distance between the first and second measuring devices 48a, 48b, stored in the memory 80.

The center calculation unit 88 calculates the center position of the wafer 11 placed on the holding surface of the temporary table 40 of the thickness measurement unit 24. Specifically, the center calculation unit 88 calculates the center position of the wafer 11 based on the coordinates of at least three points on the outer periphery of the wafer 11 detected by the detection unit 84 on the XY coordinate plane.

This point will be explained with reference to FIG8 . FIG8 schematically shows a top view of wafer 11 placed on the holding surface of temporary table 40, with the center of wafer 11 offset from the center of the holding surface. Furthermore, for convenience, bumps 15 formed on front surface 11a of wafer 11 are omitted in FIG8 .

Alternatively, FIG8 may be shown as an XY coordinate plane having the center of the holding surface of the temporary table 40 as the origin O. Furthermore, in FIG8 , the center of the wafer 11 is located at a position offset from the center of the holding surface (origin O), that is, at the coordinates (Xc, Yc) on the XY coordinate plane.

Here, if the coordinates of three points on the outer periphery of wafer 11 on the XY coordinate plane are set to ( _X1 , _Y1 ), ( _X2 , _Y2 ), and ( _X3 , _Y3 ), then the coordinates of the center of wafer 11 on the XY coordinate plane (Xc, Yc) can be calculated using the following equations 1 and 2.

[Formula 1] …(Formula 1)

[Formula 2] …(Formula 2)

Furthermore, the center calculation unit 88 calculates the coordinates (Xc, Yc) of the center of the wafer 11 on the XY coordinate plane by substituting the specific values of the coordinates on the XY coordinate plane of at least three points on the outer periphery of the wafer 11 detected by the detection unit 84 into the above-mentioned equations 1 and 2.

The adjustment unit 90 adjusts the center point of the suction pad 22 to a position corresponding to the center of the wafer 11 when the wafer 11 is about to be unloaded from the temporary table 40 by the transfer unit 14. Specifically, the adjustment unit 90 operates the actuator of the transfer base 16 and the transfer arm 18 housed in the transfer unit 14 so that the center point of the suction pad 22 at this time is at the coordinates (Xc, Yc) on the XY coordinate plane.

9 is a flow chart schematically showing an example of a resin coating method for coating the front surface 11a of the wafer 11 with a resin layer using the resin coating apparatus 12. In this method, the thickness of the wafer 11 is first measured using the thickness measuring unit 24 (thickness measuring step: S1).

Figure 10 is a flowchart schematically illustrating an example of the detailed sequence of the thickness measurement step (S1). In this thickness measurement step (S1), wafer 11 is first held by temporary stage 40 (temporary stage holding step: S11). Figure 11 is a side view schematically illustrating the temporary stage holding step (S11).

In this temporary table holding step (S11), the transfer unit 14 moves the wafer 11 onto the temporary table 40 with the front surface 11a of the wafer 11 facing upward. Specifically, the transfer unit 14 first removes the wafer 11 from the cassette 2 with the suction pad 22 sucking and holding the front surface 11a of the wafer 11.

Next, the transport unit moving mechanism is operated to position the transport unit 14 that is transporting the wafer 11 near the thickness measuring unit 24. Next, the Y-axis moving mechanism 28 is operated to position the wafer 11 to a position where the transport unit 14 can move the wafer 11 onto the holding surface of the temporary table 40 (e.g., a position away from the first measuring device 48a and the second measuring device 48b).

Next, with the back surface 11b of the wafer 11 facing downward, that is, with the front surface 11a of the wafer 11 being held by suction on the lower side of the suction pad 22, the transfer unit 14 is operated so that the center point of the suction pad 22 approaches the center of the holding surface of the temporary table 40. Next, the operation of the suction source connected to the suction holes provided on the holding surface of the suction pad 22 is stopped.

This places the back surface 11b of the wafer 11 on the holding surface of the temporary table 40. Furthermore, the diameter of this holding surface (the outer diameter of the frame 42) is shorter than the diameter of the wafer 11. Therefore, the outer periphery of the wafer 11 is positioned outside the holding surface of the temporary table 40.

Next, while the suction source connected to the bottom surface of the porous plate 44 of the temporary table 40 via a valve is activated, the valve is opened. This allows the central area of the back surface 11b of the wafer 11 to be held by the holding surface of the temporary table 40. This completes the temporary table holding step (S11).

After the temporary stage holding step (S11), the coordinates of points on the outer periphery of the wafer 11 are detected with reference to the measurement results of the first measuring device 48a or the second measuring device 48b (detection step: S12). Figure 12 is a side view schematically showing the detection step (S12).

In this detection step (S12), projection of the laser beam L1 from the first measuring device 48a or projection of the laser beam L2 from the second measuring device 48b begins. Next, the Y-axis movement mechanism 28 moves the temporary stage 40 along the Y-axis direction so that a point on the outer periphery of the wafer 11 passes through the measurement position between the first measuring device 48a and the second measuring device 48b.

That is, in the detection step (S12), the following measurement results can be obtained: measurement values of the first measuring device 48a or the second measuring device 48b in each of the states where the wafer 11 does not exist at the measurement position, where the outer periphery of the wafer 11 exists, and where a portion inside the outer periphery of the wafer exists.

Here, if these laser beams L1 and L2 are irradiated near the chamfered outer edge of wafer 11, they are reflected in directions different from those toward the first and second measuring devices 48a and 48b. In this case, the distance measurement to wafer 11 by each of the first and second measuring devices 48a and 48b becomes impossible.

On the other hand, when this laser beam is projected onto the flat front surface 11a or back surface 11b of wafer 11, each of first measuring device 48a and second measuring device 48b can measure the distance to wafer 11. Therefore, the measurement results obtained by first measuring device 48a or second measuring device 48b in the inspection step (S12) include not only the measured value indicating the distance to wafer 11, but also an error value indicating that measurement was impossible.

Furthermore, in the measurement results, the coordinates on the XY coordinate plane where the distance to the wafer 11 cannot be measured are detected as the coordinates of points on the outer periphery of the wafer 11. With the above, the detection step (S12) is completed.

After the detection step (S12), the first measuring device 48a measures the distance between the first measuring device 48a and the wafer 11, and the second measuring device 48b measures the distance between the second measuring device 48b and the wafer 11 (measurement step: S13). Figure 13 is a side view schematically showing the measurement step (S13).

In this measurement step (S13), first, in a planar perspective, the measured point on the wafer 11, which is a predetermined distance d closer to the center of the wafer 11 than the point on the outer periphery of the wafer 11 detected in the detection step (S12) and is located on the outer side of the holding surface of the temporary workbench 40, is positioned at a measurement position between the first measuring device 48a and the second measuring device 48b.

Next, the first detector 48a projects the laser beam L1 downward and receives the laser beam L1 reflected by the front surface 11a of the wafer 11. Similarly, the second detector 48b projects the laser beam L2 upward and receives the laser beam L2 reflected by the back surface 11b of the wafer 11.

This allows the measurement of the distance i1 from the first measuring device 48a to the front surface 11a of the wafer 11 (the gap between the first measuring device 48a and the wafer 11), and the distance i2 from the second measuring device 48b to the back surface 11b of the wafer 11 (the gap between the second measuring device 48b and the wafer 11). This completes the measurement step (S13).

After the measurement step (S13), the thickness of the wafer 11 is calculated (thickness calculation step: S14). Specifically, the thickness calculation unit 86 of the control unit 76 calculates the thickness of the wafer 11 by subtracting the distance i1 between the first measuring device 48a and the wafer 11 and the distance i2 between the second measuring device 48b and the wafer 11 measured in the measurement step (S13) from the distance between the first measuring device 48a and the second measuring device 48b stored in the memory unit 80.

The thickness measurement step ( S1 ) is now complete. Following the thickness measurement step ( S1 ), the front surface 11a of the wafer 11 is coated with a resin layer using the resin coating unit 50 . Specifically, the sheet supply unit first places the sheet on the worktable 54 of the resin coating unit 50 (sheet placement step: S2 ). The sheet placement step ( S2 ) can also be omitted.

After the sheet loading step (S2), the back side 11b of the wafer 11 is held by the holding plate 74 (holding step S3). Specifically, the transfer unit 14 first unloads the wafer 11 from the temporary workbench 40 with the suction pad 22 sucking and holding the front side 11a of the wafer 11.

Next, the transport unit moving mechanism is operated to position the transport unit 14 transporting the wafer 11 near the resin coating unit 50. Next, the suction pad 22 is turned over so that the back surface 11b of the wafer 11 faces upward, that is, the front surface 11a of the wafer 11 is attracted and held by the upper side of the suction pad 22.

Next, the transport unit 14 is operated to bring the center point of the suction pad 22 closer to the center of the holding surface of the holding plate 74. The suction source connected to the suction holes provided on the holding surface of the suction pad 22 is then stopped. Next, the suction source connected to the top surface of the porous plate of the holding plate 74 is activated. This allows the back surface 11b of the wafer 11 to be held by the holding surface of the holding plate 74.

After this holding step (S3), the conveying unit 14 is operated to retract the suction pad 22 from between the holding plate 74 and the worktable 54. Furthermore, liquid UV-curable resin is supplied from the resin supply source to the upper surface of the worktable 54 (resin supply step: S4). This resin supply step (S4) may also be performed before the holding step (S3).

After the holding step (S3) and the resin supply step (S4), the holding plate 74 is brought closer to the worktable 54 (approaching step: S5). At this time, the distance between the holding plate 74 and the worktable 54 is determined based on the thickness of the wafer 11 measured in the thickness measurement step (S1). For example, this distance is set to a value equal to the sum of the thickness of the wafer 11 measured in the thickness measurement step (S1) and the predetermined thickness of the resin layer covering the front surface 11a of the wafer 11, which has been stored in the memory unit 80.

After this approaching step (S5), the liquid UV-curable resin is cured (curing step: S6). Specifically, shutter 60 is first opened. Next, ultraviolet light is irradiated from light source 58 through filter 62 and stage 54 onto the UV-curable resin. This cures the UV-curable resin that contacts the front surface 11a of wafer 11. As a result, the front surface 11a of wafer 11 is coated with a resin layer.

In the resin coating method described above, temporary stage 40 holding wafer 11 can be moved along the Y-axis direction. Therefore, in the resin coating method described above, after detecting the coordinates of a point on the outer periphery of wafer 11 with reference to the measurement results of first measuring device 48a or second measuring device 48b, the thickness of wafer 11 can be measured at a predetermined distance from the measured point near the center of wafer 11. Thus, in the resin coating method described above, by setting the predetermined distance according to the type of wafer 11, it is possible to appropriately measure the thickness of wafer 11 while suppressing variations in the thickness of the resin layer coating the front surface of wafer 11.

Furthermore, the resin coating method of the present invention can also efficiently align wafers 11 after they are loaded into the resin coating unit 50. This point will be explained below. First, within the cassette 2, wafers 11 are already accommodated in a space wider than the wafer itself, and their center may sometimes deviate from the horizontal center of the cassette 2.

At this time, when the transport unit 14 unloads the wafer 11 from the cassette 2, the center point of the suction pad deviates from the position corresponding to the center of the wafer 11. In this state, when the transport unit 14 loads the wafer 11 onto the holding surface of the temporary table 40 of the thickness measurement unit 24, the center of the wafer 11 and the center of the holding surface of the temporary table 40 also deviate.

In contrast, in the resin coating apparatus 12 described above, because the temporary table 40 is connected to the rotation drive source via the θ table 38, the coordinates of multiple points on the outer periphery of the wafer 11 can be detected. Specifically, by rotating the temporary table 40 at an arbitrary angle multiple times and performing the aforementioned detection step (S12) before and after each rotation, the coordinates of multiple points on the outer periphery of the wafer 11 can be detected.

As long as the coordinates of at least three points on the outer periphery of the wafer 11 can be detected in this manner, the center calculation unit 88 of the control unit 76 can calculate the center of the wafer 11 as described above. That is, the resin coating method of the present invention may also include a center calculation step, which calculates the center of the wafer 11 based on the coordinates of at least three points on the outer periphery of the wafer 11 detected in the detection step (S12).

Furthermore, as long as the center of the wafer 11 can be calculated in this manner, the adjustment unit 90 of the control unit 76 can adjust the center point of the attraction pad 22 to a position corresponding to the center of the wafer 11 when the wafer 11 is unloaded from the temporary table 40 by the transport unit 14, as described above. In other words, the resin coating method of the present invention may also include an adjustment step for adjusting the center point of the attraction pad 22 to a position corresponding to the center of the wafer 11 when the wafer 11 is unloaded from the temporary table 40 by the transport unit 14.

By performing the center calculation step and the adjustment step, it is not necessary to install a mechanism for aligning the wafers 11 in the resin coating apparatus 12 when aligning the wafers 11 carried into the resin coating unit 50. Therefore, it is possible to suppress an increase in the manufacturing cost of the resin coating apparatus 12.

Furthermore, the resin coating method of the present invention can be implemented using a resin coating apparatus having components different from those of the resin coating apparatus 12 described above. For example, the second measuring device 48b included in the thickness measuring unit 24 of the resin coating apparatus 12 may be omitted. In this case, the interval between the temporary stage and the first measuring device 48a may be pre-stored in the memory unit 80 of the control unit 76.

In such a resin coating apparatus, the thickness of the wafer 11 can be calculated by subtracting the distance between the first measuring device 48a and the wafer 11 measured by the first measuring device 48a from the distance between the temporary stage and the first measuring device 48a stored in the memory unit 80.

However, wafer 11 may warp. That is, the front surface 11a and back surface 11b of wafer 11 may bend in an arc shape. Therefore, in this type of resin coating device, there is a concern that the thickness of wafer 11 cannot be accurately measured. For example, if wafer 11 warps so that the outer periphery of front surface 11a of wafer 11 is higher than the center, the thickness of wafer 11 calculated as described above may be greater than the actual thickness of wafer 11.

On the other hand, in such resin coating systems, wafer 11 warping can be suppressed by suctioning and holding wafer 11 on a temporary table with a circular holding surface longer in diameter than wafer 11. However, it is not easy to accurately measure the thickness of the porous plate used to suction and hold wafer 11 on such a temporary table. Therefore, even in such resin coating systems, there is a concern that the thickness of wafer 11 cannot be accurately measured.

Furthermore, the first and second measuring devices 48a, 48b of the thickness measuring unit 24 of the resin coating device 12 can be replaced with contact-type thickness measuring devices. However, when measuring the thickness of the wafer 11 using a contact-type thickness measuring device, there is a concern that the bumps 15 formed on the front surface 11a of the wafer 11 may be damaged.

Therefore, the resin coating method of the present invention is preferably implemented using the above-mentioned resin coating apparatus 12. Specifically, the resin coating method of the present invention is preferably implemented using the resin coating apparatus 12 equipped with the following thickness measuring unit 24: a non-contact first measuring device 48a and a second measuring device 48b, and a temporary stage 40 having a circular holding surface with a diameter shorter than that of the wafer 11.

Furthermore, in the resin coating method of the present invention, the front surface 11a of the wafer 11 can be integrated with the ring frame by means of a tape before the wafer 11 is loaded into the resin coating unit 50. The tape comprises a tape base having a diameter longer than that of the wafer 11, and an adhesive layer provided in a ring shape on the surface of the tape base facing the wafer 11 and the ring frame.

Furthermore, the adhesive layer is provided so as to be attached to one side of the annular frame and to an area near the outer periphery of the front surface 11a of the wafer 11 where the bumps 15 are not provided. In other words, the adhesive layer is not provided on the area of the tape substrate facing the area of the front surface 11a of the wafer 11 where the bumps 15 are provided.

Furthermore, in this case, the distance between the retaining plate 74 and the workbench 54 is set to be equal to the following value: the sum of the thickness of the wafer 11 measured in the thickness measurement step (S1), the predetermined thickness of the resin layer on the front surface 11a of the coated wafer 11 recorded in the memory unit 80, and the thickness of the tape attached to the front surface 11a of the wafer 11.

Furthermore, the structures and methods of the above-described embodiments may be implemented with appropriate modifications within the scope of the present invention. For example, in the resin coating device of the present invention, the Y-axis movement mechanism 28 of the thickness measuring unit 24 may be replaced with a Y-axis movement mechanism that moves the first measuring device 48a and the second measuring device 48b along the Y-axis.

That is, in the resin coating device of the present invention, as long as the temporary table 40, the first measuring device 48a, and the second measuring device 48b can move relative to each other in a direction parallel to the holding surface of the temporary table 40, the components used for the movement are not limited.

Similarly, in the resin coating apparatus of the present invention, the lifting mechanism 68 of the resin coating unit 50 can be replaced with a lifting mechanism for lifting the work table 54. In other words, in the resin coating apparatus of the present invention, as long as the retaining plate 74 and the work table 54 can move relative to each other in the vertical direction, the components used for such movement are not limited.

Furthermore, in the resin coating method of the present invention, the liquid resin used to form the resin layer on the front surface 11a of the wafer 11 is not limited to a UV-curable resin. For example, such a resin may be substituted with a thermosetting resin. In this case, the resin curing device 56 of the resin coating unit 50 may also be replaced with a heater.

2: Cassette 4: Top plate 6a, 6b: Side walls 8: Wafer support groove 10: Connecting member 11: Wafer 11a: Front surface 11b: Back surface 11c: Side surface 12: Resin coating device 13: Area 14: Transfer unit 15: Bump 16: Transfer base 18: Transfer arm 18a: First arm 18b: Second arm 18c: Second joint 18d: Third arm 18e: Spindle 18f: Connecting section 20: Non-contact sensor 22: Suction pad 24: Thickness measurement unit 26: First support structure 26a, 26b, 32a, 46a, 66a: Vertical mounting section 26c, 46b, 46c: Overlap mounting section 28: Y-axis movement mechanism (first movement mechanism) 30: Guide rail 32: Movement member 32b: Table support 34: Screw shaft 36: Motor 38: θ table 40: Temporary table 42: Frame 44: Perforated plate 46: Second support structure 46d: Lower protrusion 46e: Upper protrusion 48a: First measuring device 48b: Second measuring device 50: Resin coating unit 52: Base 54: Table 56: Resin hardener 58: Light source 60: Light gate 62: Filter 64: Exhaust pipe 66: Support structure 66b: Eaves 68: Elevator mechanism (second moving mechanism) 70: Main actuator 72: Sub-actuator 74: Holding plate 76: Control unit 78: Processing unit 80: Memory unit 82: Drive unit 84: Detection unit 86: Thickness calculation unit 88: Center calculation unit 90: Adjustment unit d: Distance i1: Distance between the first measuring instrument and the wafer (distance from the first measuring instrument to the front surface of the wafer) i2: Distance between the second measuring instrument and the wafer (distance from the second measuring instrument to the back surface of the wafer) L1, L2: Laser beams O: Origin S1: Thickness measurement step S2: Sheet loading step S3: Holding step S4: Resin supply step S5: Approaching step S6: Curing step S11: Temporary stage holding step S12: Inspection step S13: Measurement step S14: Thickness calculation step X, Y, Z: Directions Xc, Yc: Coordinates

Figure 1(A) is a schematic top view of an example wafer, and Figure 1(B) is a schematic cross-sectional view of an example wafer. Figure 2 is a schematic perspective view of an example wafer cassette containing wafers. Figure 3 is a schematic block diagram of an example resin coating device. Figure 4 is a schematic perspective view of an example transport unit. Figure 5 is a schematic perspective view of an example thickness measurement unit. Figure 6 is a schematic perspective view of an example resin coating unit. Figure 7 is a schematic block diagram of an example control unit. Figure 8 is a schematic top view of an example wafer placed on the holding surface of a temporary table, with the center of the wafer offset from the center of the holding surface. Figure 9 is a flowchart schematically illustrating an example of a resin coating method for coating the front surface of a wafer with a resin layer. Figure 10 is a flowchart schematically illustrating an example of a detailed sequence of thickness measurement steps. Figure 11 is a side view schematically illustrating the temporary stage holding step. Figure 12 is a side view schematically illustrating the inspection step. Figure 13 is a side view schematically illustrating the measurement step.

S11: Temporarily hold the workbench step

S12: Detection step

S13: Measurement step

S14: Thickness calculation step

Claims (4)

A resin coating method for coating the front surface of a circular wafer with a resin layer is characterized by comprising the following steps: a thickness measuring step of measuring the thickness of the wafer; a holding step of holding the back surface of the wafer with a holding plate; a resin supplying step of supplying liquid resin to a worktable facing the holding plate; an approaching step of bringing the holding plate and the worktable closer together so that the distance between the holding plate and the worktable becomes a distance determined by the thickness of the wafer measured in the thickness measuring step; and a curing step of curing the liquid resin. The thickness measuring step comprises: A temporary table holding step is performed by using a temporary table having a holding surface and being rotatable about a straight line passing through the center of the holding surface and perpendicular to the holding surface as a rotation axis to hold the wafer whose outer periphery is positioned outside the holding surface in a planar viewing angle; The detection step comprises moving the temporary stage and the first and second measuring tools, which face each other in a direction perpendicular to the holding surface, relative to each other in a direction parallel to the holding surface so that a point on the outer periphery passes through a measurement position between the first and second measuring tools. The first measuring tool measures the distance between the first measuring tool and the wafer, or the second measuring tool measures the distance between the second measuring tool and the wafer, thereby obtaining a measurement result, and detecting the coordinates of the point with reference to the measurement result. A measuring step comprises: positioning a point on the wafer, which is located outside the holding surface and a predetermined distance closer to the center of the wafer than the point in a planar view, at the measurement position; measuring the distance between the first measuring tool and the wafer using the first measuring tool, and measuring the distance between the second measuring tool and the wafer using the second measuring tool; and A thickness calculation step comprises: calculating the thickness of the wafer by subtracting the following distances from the distance between the first measuring tool and the wafer: the distance between the first measuring tool and the wafer measured by the first measuring tool with the point positioned at the measurement position; and the distance between the second measuring tool and the wafer measured by the second measuring tool. The resin coating method of claim 1 further comprises the following steps: a center calculation step of calculating the center of the wafer from the coordinates of at least three points on the outer periphery detected in the detection step; and an adjustment step of adjusting the center point of the attraction pad when the wafer is removed from the temporary stage by a transport unit having an attraction pad for attracting the wafer and transporting the wafer to a position corresponding to the center of the wafer. A resin coating device is provided for coating the front surface of a circular wafer with a resin layer. The resin coating device is characterized by: comprising: a thickness measuring unit for measuring the thickness of the wafer; a resin coating unit for coating the front surface of the wafer with the resin layer; and a control unit for controlling the thickness measuring unit and the resin coating unit. The thickness measuring unit comprises: a temporary worktable having a holding surface for holding the wafer and rotatable about a straight line passing through the center of the holding surface and perpendicular to the holding surface as a rotation axis; a first measuring device and a second measuring device facing each other in a direction perpendicular to the holding surface; and The first moving mechanism moves the temporary worktable, the first measuring device, and the second measuring device relative to each other in a direction parallel to the holding surface. The first measuring device measures the distance between the first measuring device and the wafer positioned at a measuring position between the first measuring device and the second measuring device. The second measuring device measures the distance between the second measuring device and the wafer positioned at the measuring position. The resin coating unit comprises: a holding plate for holding the wafer; a worktable facing the holding plate; a resin supply source for supplying liquid resin to the worktable; a second moving mechanism for adjusting the distance between the holding plate and the worktable; and a resin hardener for hardening the liquid resin. The control unit comprises: A drive unit drives the first moving mechanism so that a point on the outer periphery of the wafer, whose outer periphery is positioned outside the holding surface in a planar view, passes through the measurement position, and drives the second moving mechanism so that the distance between the holding plate holding the wafer and the worktable to which the liquid resin is supplied is determined according to the thickness of the wafer; A detection unit detects the coordinates of the point on the outer periphery by referring to the measurement results of the first measuring device or the second measuring device when the point passes through the measurement position; and The thickness calculation unit calculates the thickness of the wafer by subtracting the following distances from the distance between the first measuring tool and the wafer measured by the first measuring tool and the distance between the second measuring tool and the wafer measured by the second measuring tool, with a point on the wafer to be measured, located a predetermined distance from the point near the center of the wafer and outside the holding surface, at the measurement position, from the distance between the first measuring tool and the second measuring tool. The resin coating apparatus of claim 3 is further provided with: a transport unit having an attraction pad for attracting the wafer and transporting the wafer; the control unit further comprising: a center calculation unit for calculating the center of the wafer based on the coordinates of at least three points on the outer periphery detected by the detection unit; and an adjustment unit for adjusting the center point of the attraction pad to a position corresponding to the center of the wafer when the transport unit is about to remove the wafer from the temporary worktable.