Protection member forming device

Abstract

To stably form a protection member having a predetermined thickness without being thermally affected.SOLUTION: A protection member forming device 1 includes: an encoder 45 that detects a position of a holding table 31 moved by a lifting mechanism 40; a distance sensor 35 that measures a distance between an expansion table 50 and the holding table 31; a reference value storage part 91 that moves the holding table 31 to a preset preparation position, measures a distance A between the expansion table 50 and the holding table 31 by the distance sensor 35, and stores the measured value A as a reference value; an offset value setting part 92 that moves the holding table 31 to a preparation position before forming a protection member, and calculates a difference between a distance B between the expansion table 50 and the holding table 31 measured by a distance sensor 35 and a reference value A, and sets the difference as an offset value ε; and a control part 90 that moves the holding table 31 to a position to which the offset value ε is added to the preparation position set in advance when expanding a liquid resin r.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a protective member forming apparatus for forming a protective member on one surface of a wafer. [Background technology]

[0002] For example, wafers used in the manufacture of semiconductor devices such as ICs and LSIs used in electronic devices are obtained by cutting a single crystal ingot of silicon or the like with a cutting device such as a blade saw or a wire saw to produce sliced ​​wafers, and then flattening both surfaces of the sliced ​​wafers with a grinding device or a polishing device. Devices such as ICs and LSIs are then formed on the front surface of the wafer with both surfaces flattened in this way, the back surface of the wafer on which these devices are formed is ground to thin the wafer to a predetermined thickness, and the thinned wafer is then cut with a dicing saw or the like to separate into individual devices.

[0003] Sliced ​​wafers cut from an ingot have warpage and undulations on the surface of both sides due to differences in the magnitude of processing strain that occurs on both sides during cutting using a cutting device such as a blade saw. For this reason, a processing method is practiced in which a protective member such as an ultraviolet-curable resin is formed on one side of the sliced ​​wafer to flatten that side, the other side of the sliced ​​wafer is ground while the flat side of the protective member is held on the holding surface of a chuck table to flatten the other side, and then the protective member is peeled off from the sliced ​​wafer. Patent Documents 1 to 3, for example, propose protective member forming devices for forming a protective member on one side of a sliced ​​wafer.

[0004] In the protective member forming device, a liquid resin is spread over the entire surface of one side of a sliced ​​wafer (hereinafter simply referred to as "wafer") and then hardened to form a protective member. When spreading the liquid resin over the entire surface of one side of the wafer, a sheet is placed on an extension table, the liquid resin is dripped onto the sheet, a holding table placed above the extension table is lowered together with the wafer held on it to a predetermined height position, and the liquid resin on the sheet is pressed by the wafer to spread the liquid resin. If the liquid resin is an ultraviolet-curable resin, the ultraviolet-curable resin is irradiated with ultraviolet light to harden the ultraviolet-curable resin. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-188058 [Patent Document 2] Japanese Patent Publication No. 2020-188230 [Patent Document 3] Japanese Patent Publication No. 2024-030724 Summary of the Invention [Problem to be solved by the invention]

[0006] When the holding table is lowered to spread the liquid resin, the holding table is lowered a predetermined amount from a preset preparation position (initial position) to a set height position to spread the liquid resin, and then the ultraviolet-curable resin is cured by irradiating it with ultraviolet light. However, the reaction heat generated when the ultraviolet-curable resin hardens heats and thermally expands the extension table and the holding table. Therefore, when the holding table is lowered a predetermined amount from the preparation position to form a protective member on the next wafer, the distance between the holding table and the extension table is reduced by the sum of the thermal expansion amounts of the holding table and the extension table.

[0007] Therefore, the liquid resin is pressed against the wafer by an amount equal to the sum of the thermal expansion amounts of the holding table and the extension table, causing the liquid resin to leak out from the outer edge of the wafer, resulting in the problem that the thickness of the protective member formed by the hardening of the liquid resin gradually becomes thinner.

[0008] The present invention has been made in consideration of the above problems, and its purpose is to provide a protective member forming device that can form a protective member of a predetermined thickness without being affected by heat. [Means for solving the problem]

[0009] A first invention for solving the above problems is a protective member forming device comprising: an extension table that spreads dropped liquid resin; a resin nozzle that drips the liquid resin; a holding table that is arranged above and facing the extension table; a lifting mechanism that raises and lowers the holding table and the extension table relatively to spread the liquid resin; and a curing unit that hardens the spread liquid resin, the protective member forming device comprising: a position detection unit that detects a position of the extension table or the holding table moved by the lifting mechanism; a distance measurement unit that measures the distance between the extension table and the holding table; a reference value storage unit that moves the extension table or the holding table to a preset preparation position by the lifting mechanism, measures the distance between the extension table and the holding table with the distance measurement unit, and stores the measured value as a reference value; The present invention is characterized in that it comprises an offset value setting unit that moves the extension table or the holding table to the preparation position before expanding the liquid resin, calculates the difference between the distance between the extension table and the holding table measured by the distance measuring unit and the reference value, and sets the difference as an offset value; and a control unit that, when expanding the liquid resin, uses the lifting mechanism to move the extension table or the holding table to a position to which the offset value has been added to the previously set preparation position, thereby increasing the distance between the extension table and the holding table, and then uses the lifting mechanism to move them closer by a predetermined amount, or moves the extension table or the holding table to the previously set preparation position by the lifting mechanism, and then uses the lifting mechanism to move them closer by an amount obtained by subtracting the offset value from the predetermined amount.

[0010] The second invention is a protective member forming device comprising an extension table that expands dripped liquid resin, a resin nozzle that drips the liquid resin, a holding table arranged opposite to and above the extension table, a lifting mechanism that raises and lowers the holding table and the extension table relative to each other to expand the liquid resin, and a curing unit that hardens the expanded liquid resin, characterized in that it also comprises a distance measuring unit that measures the distance between the extension table and the holding table, and a control unit that measures the distance between the extension table and the holding table using the distance measuring unit and uses the lifting mechanism to bring the extension table and the holding table closer together until the measured value reaches a predetermined set value. [Effects of the Invention]

[0011] According to the first aspect of the present invention, for example, when the holding table descends from a position offset upward from the preparation position by the offset value, the amount of pressure applied to the liquid resin by the next wafer decreases by the sum of the amounts of thermal expansion of the holding table and the extension table due to the resin hardening, and ultimately the liquid resin is pressed and expanded by the same amount as when there is no thermal expansion of the holding table and the extension table. This prevents the problem of excess liquid resin being pressed and leaking out from the outer edge of the wafer, which would gradually thin the thickness of the protective member formed by the hardening of the liquid resin, and ensures that a protective member of a predetermined thickness is stably formed on the wafer.

[0012] According to the second aspect of the present invention, while the holding table is in the preparation position, the distance measuring unit measures the distance between the holding table and the extension table, and the lifting mechanism, for example, lowers the holding table until the measured value reaches a preset value. Therefore, even if the holding table and the extension table thermally expand due to the heat of reaction of the liquid resin in the previous curing process, a predetermined amount of liquid resin can always be pressed against them regardless of the thermal expansion of the holding table and the extension table. This prevents the problem of excess liquid resin being pressed against the wafer and leaking out from the outer edge, causing the thickness of the protective member formed by the curing of the liquid resin to gradually become thinner, and a protective member of the predetermined thickness is stably formed on the wafer. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a perspective view of a protective member forming apparatus according to a first aspect of the present invention. [Figure 2] 4 is a vertical cross-sectional view showing movement of a holding table to a preparation position in the protective member forming device according to the first invention. FIG. [Figure 3] 5 is a vertical cross-sectional view showing the relationship between the preparation position and the amount of thermal expansion of the holding table and the amount of thermal expansion of the extension table in the step of curing the liquid resin in the protective member forming apparatus according to the first invention. FIG. [Figure 4] 5 is a flowchart showing a procedure for determining an offset value of a holding table in the protective member forming apparatus according to the first aspect of the present invention. [Figure 5] 5(a) to 5(e) are longitudinal cross-sectional views showing a process of forming a protective member in the protective member forming apparatus according to the first invention. [Figure 6] 10 is a flowchart showing the procedure of a liquid resin spreading step in the protective member forming apparatus according to the second invention. [Figure 7] 10 is a vertical cross-sectional view showing a liquid resin spreading step in the protective member forming apparatus according to the second invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] <First Invention> [Configuration of liquid resin supply device] First, the configuration of the protective member forming device according to the first invention will be described with reference to Figures 1 to 3. In the following description, the directions of the arrows shown in Figure 1 are the X-axis (left-right direction), the Y-axis (front-rear direction), and the Z-axis (up-down direction), respectively.

[0015] The protective member forming apparatus 1 shown in FIG. 1 is an apparatus for forming a protective member on one surface (the lower surface in FIG. 1) of a disk-shaped wafer W, and includes a housing 100 and a cassette storage unit 110 arranged along the X-axis direction. Here, the cassette storage unit 110 stores a first cassette 111 and a second cassette 112 along the Y-axis direction, with the first cassette 111 storing a plurality of wafers W before the protective member is formed, and the second cassette 112 storing a plurality of wafers W on which the protective member has been formed. The wafers W are disk-shaped sliced ​​wafers cut from a cylindrical ingot such as single-crystal silicon.

[0016] The housing 100 also contains, in order from the -X axis direction (left side), components such as a first transport means 10, a second transport means 20, a temporary placement table 2, a sheet cutting table 4, a wafer holder 30, a lifting mechanism 40, an extension table 50, a curing unit 60, a dispenser 70, and a sheet transport unit 7. The configuration of each component will be described below in order.

[0017] (First conveying means) The first transport means 10 functions to remove wafers W from the first cassette 111 and transport them to the temporary placement table 2, as well as to receive wafers W with protective members formed thereon from the sheet cutting table 4 and store them in the second cassette 112, and is equipped with a robot hand 12 installed on a base 11 and a Y-axis movement mechanism 13 that moves the base 11 in the Y-axis direction together with the robot hand 12.

[0018] Here, the Y-axis movement mechanism 13 is composed of a pair of guide rails 14 arranged parallel to each other along the Y-axis direction, a rotatable ball screw 15 arranged along the Y-axis direction between these guide rails 14, and a motor 16 for rotating the ball screw 15 forward and backward, and the ball screw 15 is threadedly inserted into a nut member (not shown) that protrudes from the underside of the base 11. Therefore, when the motor 16 is started to rotate the ball screw 15 forward and backward, the base 11, on which the nut member (not shown) protrudes and into which the ball screw 15 threads, moves along the Y-axis direction together with the robot hand 12.

[0019] (Second conveying means) The second transport means 20 receives the wafer W from the temporary placement table 2 and transports it to the wafer holding section 30, and also receives the wafer W with a protective member formed thereon from the extension table 50 and transports it to the sheet cutting table 4.The second transport means 20 is equipped with a robot hand 22 installed on a base 21 and an X-axis movement mechanism 23 that moves the base 21 together with the robot hand 22 in the X-axis direction.

[0020] Here, the X-axis movement mechanism 23 is composed of a pair of guide rails 24 arranged parallel to each other along the X-axis direction, a rotatable ball screw 25 arranged between these guide rails 24 along the X-axis direction, and a motor (not shown) for rotating the ball screw 25 forward and backward, and the ball screw 25 is threadedly inserted into a nut member (not shown) protruding from the underside of the base 21. Therefore, when the motor (not shown) is started to rotate the ball screw 25 forward and backward, the base 21, on which the nut member (not shown) protruding and into which the ball screw 25 is threadedly inserted, moves along the X-axis direction together with the robot hand 22.

[0021] (Temporary table) The temporary placement table 2 is used to temporarily place the wafer W taken out from the first cassette 111 by the robot hand 12 of the first transport means 10, and the center position and orientation of the wafer W temporarily placed on the temporary placement table 2 are optically detected by the wafer detection unit 3.

[0022] (Sheet cutting table) The sheet cutting table 4 is disposed below the temporary placement table 2, and is used to place the wafer W on which the protective member is formed. The sheet S attached to the wafer W is cut along the periphery of the wafer W by the sheet cutter 5.

[0023] (Wafer holder) The wafer holding unit 30 includes a disk-shaped holding table 31, the underside of which forms a holding surface. As shown in Fig. 2, the underside of the holding table 31 that forms the holding surface has a plurality of suction holes 31a opened therein, and these suction holes 31a are connected to a suction source 34 via a pipe 33 that is connected to a suction path 32 formed inside the holding table 31. An on-off valve V1 is provided in the pipe 33.

[0024] Furthermore, a distance sensor 35, which is a distance measurement unit that optically measures the distance A between the holding table 31 and the extension table 50 without contact, is embedded in the underside of the holding table 31. Here, the distance sensor 35 measures the distance A between the holding table 31 and the extension table 50 based on the time from when the light is emitted to when it is received by a light receiving element, which receives the reflected light that is emitted from a light source such as an internal LED or laser diode and reflected on the upper surface of the extension table 50, which is the target.

[0025] (Lifting mechanism) The lifting mechanism 40 is a mechanism for raising and lowering the holding table 31 of the wafer holding unit 30 together with the wafer W held thereon by suction in the Z-axis direction, and is installed on a column 130 that stands vertically on the base 120. Specifically, the lifting mechanism 40 includes a pair of guide rails 41 vertically attached to the end surface of the column 130 in the +X-axis direction in parallel with each other, a lifting plate 42 that moves up and down in the Z-axis direction along the guide rails 41, a rotatable ball screw 43 vertically disposed between the pair of guide rails 41, a motor 44 that rotates the ball screw 43 forward and backward, and an encoder 45 that detects the number of rotations, rotation speed, rotation direction, etc. of the motor 44, and the holding table 31 of the wafer holding unit 30 is attached to the lifting plate 42. Here, the encoder 45 constitutes a position detection unit that detects the height position of the holding table 31 based on the number of rotations and rotation direction of the motor 44, and the encoder 45 and the motor 44 are electrically connected to the control unit 90. Although not shown, a nut member is attached to the rear surface of the lift plate 42, and a ball screw 43 is threadedly inserted into this nut member.

[0026] Therefore, when the motor 44 is started to rotate the ball screw 43 forward and backward, the lifting plate 42, to which a nut member (not shown) that screws onto the ball screw 43 is attached, moves up and down in the Z-axis direction along the pair of guide rails 41 together with the wafer holding portion 30 and the wafer W held by suction on the holding table 31 of the wafer holding portion 30, and the height position of the holding table 31 is detected by the encoder 45, which is a position detection unit.

[0027] (extension table) The extension table 50 installed on the base 120 is a disk-shaped member made of a light-transmitting material such as quartz glass, and its upper surface forms a flat holding surface on which the sheet S is placed. A ring-shaped suction groove 50a is formed around the periphery of the holding surface of the extension table 50.

[0028] (curing unit) The curing unit 60 is disposed below the extension table 50, and as will be described later, irradiates ultraviolet (UV) rays onto a liquid resin r (see FIG. 3), which is an ultraviolet curable resin, supplied onto a sheet S placed on the extension table 50, thereby curing the liquid resin r. As shown in FIGS. 2 and 3, the curing unit 60 includes a case 61 whose upper surface is closed by the extension table 50. Here, the case 61 includes a side wall 61A and a bottom plate 61B, and the space formed by these side wall 61A, bottom plate 61B, and extension table 50 houses a plurality of UV lamps 62 that irradiate ultraviolet rays toward the liquid resin r.

[0029] 2, four suction holes 61a (only two are shown in FIG. 2) are formed on the upper surface of the side wall 61A of the case 61, and these suction holes 61a and the ring-shaped suction groove 50a formed around the extension table 50 are connected to a suction source 65 via a pipe 64 connected to a suction path 63 formed in the side wall 61A of the case 61. An on-off valve V2 is provided in the pipe 64.

[0030] (Dispenser) The dispenser 70 supplies a predetermined amount of liquid resin r stored in a resin tank 80 installed in the base 120 to the upper surface of the sheet S held on the upper surface of the extension table 50, and is connected to the resin tank 80 via a pipe 82 and to a resin nozzle 81 via a pipe 83.

[0031] (sheet transport section) The sheet conveying unit 7 pulls out the sheet S from the sheet roll R on which the sheet S is wound in a roll shape and conveys it to the extension table 50. The sheet conveying unit 7 includes a clamp unit 8a attached to the side of an arm 8 that is movable in the X-axis direction. Therefore, when the arm 8 moves in the -X-axis direction with the clamp unit 8a gripping the end of the sheet S wound around the sheet roll R, the sheet S is pulled out from the sheet roll R and held on the upper surface of the extension table 50. The sheet S held on the extension table 50 is then cut to an appropriate length. Note that the sheet S is made of a film such as polyethylene terephthalate (PET), which is a light-transmitting material that transmits ultraviolet light. Note that if the liquid resin is a thermosetting type, the sheet S does not have to be a light-transmitting material.

[0032] [Function of the protective member forming device] Next, the operation of the protective member forming apparatus 1 configured as above, that is, the procedure for forming a protective member on one surface of the wafer W, will be described.

[0033] To form a protective member on one side of the wafer W, as shown in Fig. 5(a), a thin, rectangular, transparent sheet S is supplied onto an extension table 50 provided on the upper surface of a case 61 of a curing unit 60. That is, in the sheet conveying section 7 shown in Fig. 1, one end of the sheet S wound around a sheet roll R is gripped by a clamp portion 8a of an arm 8, and the arm 8 moves in the -X-axis direction in Fig. 1, whereby the sheet S is supplied and set on the extension table 50 (sheet supplying step). Then, the on-off valve V2 shown in Fig. 2 opens, and the negative pressure generated in the suction source 65 is transmitted via the piping 64 and the suction path 63 to the suction groove 50a and the suction hole 61a opening in the upper surface of the extension table 50, and the sheet S is attracted by this negative pressure and held by suction on the upper surface of the extension table 50.

[0034] Next, the liquid resin r stored in the resin tank 80 shown in Figure 1 is sucked into the dispenser 70 via piping 82, and a predetermined amount of liquid resin r is supplied from the dispenser 70 to the resin nozzle 81 via piping 83, and as shown in Figure 5 (b), a predetermined amount of liquid resin r is dripped from the resin nozzle 81 onto the center of the upper surface of the sheet S held on the upper surface of the extension table 50 (liquid resin supply process).

[0035] 1 removes a wafer W from a first cassette 111 and temporarily places the wafer W on the temporary placement table 2. The wafer detection unit 3 optically detects the center position and orientation of the wafer W temporarily placed on the temporary placement table 2. The wafer W, whose center position and orientation have been detected in this manner, is then transported by the second transport unit 20 to the wafer holding unit 30 and suction-held on the holding surface (lower surface) of the holding table 31 of the wafer holding unit 30 (wafer holding step). That is, when the on-off valve V1 shown in FIG. 2 opens, negative pressure generated in the suction source 34 is transmitted via the piping 33 and the suction path 32 to the plurality of suction holes 31a opening in the lower surface of the holding table 31, and the wafer W is suction-held on the lower surface of the holding table 31 by the negative pressure, as shown in FIG. 5(c).

[0036] Meanwhile, in the sheet conveying section 7, with one end of the sheet S wound around the sheet roll R being gripped by the clamp section 8a, the arm 8 moves in the −X-axis direction, whereby the sheet S is pulled out from the sheet roll R and conveyed to the extension table 50. Then, the sheet S conveyed to the extension table 50 is sucked and held on the holding surface of the extension table 50 as described above.

[0037] As described above, when the wafer W is held by suction on the underside of the holding table 31, the lifting mechanism 40 lowers the holding table 31 together with the wafer W held thereon, and as shown in Figure 5(d), the liquid resin r dropped onto the sheet S is pushed out by the wafer W (expansion process).

[0038] Then, when the liquid resin r is spread to a uniform thickness on the sheet S by the wafer W descending together with the holding table 31, the holding table 31 is raised by the lifting mechanism 40 and separated from the wafer W, as shown in Fig. 5(e), leaving the sheet S, the liquid resin r, and the wafer W on the extension table 50 side. Then, when the multiple UV lamps 62 provided in the curing unit 60 are turned on from this state, ultraviolet (UV) rays emitted upward from each UV lamp 62 pass through the transparent, light-transmitting extension table 50 and the sheet S and are irradiated onto the liquid resin r, which is cured by the ultraviolet rays. As a result of the curing of the liquid resin r, a protective member consisting of the sheet S and cured resin is formed on one side of the wafer W (curing process).

[0039] The wafer W having the protective member formed on one surface through the above process is transported by the second transport means 20 to the sheet cutting table 4, and on the sheet cutting table 4, the sheet S attached to the wafer W is cut into a circle along the outer periphery of the wafer W by the sheet cutter 5. Then, the wafer W from which the sheet S has been cut in this manner is transported by the first transport means 10 to the second cassette 112 and stored in the second cassette 112, completing the series of steps for forming the protective member on the wafer W.

[0040] The wafer W having a protective member formed on one side is suction-held with the protective member facing down on the holding surface of a chuck table of a grinding device (not shown), and the other side of the wafer W, on which warpage or waviness remains, is ground to a flat surface. Next, the protective member is peeled off and removed from one side of the wafer W, and then the wafer W is suction-held with the other side, which has been ground to a flat surface, facing down on the holding surface of the chuck table, and the one side on which warpage or waviness remains is ground to a flat surface. As a result, both sides of the wafer W are finished to be flat and free of warpage or waviness.

[0041] 2 and 5(c), the holding table 31 is lowered a predetermined distance from a preset preparation position (initial position) to a set height position to spread the liquid resin r, and then, as shown in FIGS. 3 and 5(e), the liquid resin r is cured by irradiation with ultraviolet light from the UV lamps 62. The reaction heat generated when the liquid resin r is cured heats the holding table 31 and the extension table 50, causing thermal expansion of the holding table 31 and the extension table 50 by δ1 and δ2, respectively, as shown by the dashed lines in FIG. 3. Therefore, when the holding table 31 is set to the preparation position shown in FIGS. 2 and 5(c) in preparation for forming a protective member on the next wafer W, the distance between the holding table 31 and the extension table 50 is reduced by the sum (δ1 + δ2) of the thermal expansion amounts δ1 and δ2 of the holding table 31 and the extension table 50.

[0042] Therefore, as mentioned above, if the holding table 31 is lowered a predetermined amount from a predetermined preparation position (initial position) as in the conventional method, the liquid resin r is pressed down by an amount equal to the sum of the thermal expansion amounts δ1 and δ2 of the holding table 31 and the extension table 50 (δ1 + δ2), causing the liquid resin r to leak out from the outer edge of the wafer W, resulting in the problem that the thickness of the protective member formed by the hardening of the liquid resin r gradually becomes thinner.

[0043] Therefore, in this embodiment, as shown in Figure 5(c), before the wafer W held on the holding table 31 spreads the liquid resin r on the sheet S, the offset value ε is the sum (= δ1 + δ2) of the thermal expansion amounts δ1 and δ2 of the holding table 31 and the extension table 50 due to the heat generated when the liquid resin r hardens, and the holding table 31 is offset upward from the preparation position by this offset value ε (= δ1 + δ2).

[0044] The offset value ε of the holding table 31 is obtained by performing calibration, prior to entering the production stage in which the protective member forming apparatus 1 continuously forms protective members on one side of each of a plurality of wafers W that will become products, to measure the amounts of thermal expansion δ1 and δ2 of the holding table 31 and the extension table 50 due to the heat of reaction that occurs when the liquid resin r spread by the wafers W is cured. Once the offset value ε of the holding table 31 is determined by calibration, in the subsequent production stage, the holding table 31 is lowered from a position offset upward from the preparation position by the offset value ε, and the liquid resin r is spread by the wafers W held by the holding table 31. This allows the liquid resin r to be appropriately spread, thereby stably forming protective members of a predetermined thickness on one side of the wafers W.

[0045] The procedure for determining the offset value ε of the holding table 31 by calibration will now be described with reference to the flowchart shown in FIG.

[0046] During calibration, the lifting mechanism 40 moves the holding table 31 (step S1), and the height position is detected by the encoder 45 (step S2). Then, the control unit 90 determines whether the holding table 31 has reached a predetermined preparation position (see FIG. 2) (step S3), and if the holding table 31 has not reached the preparation position (step S3: No), the control unit 90 repeats the processes of steps S1 to S3.

[0047] When the holding table 31 reaches the preparation position (step S3: Yes), the movement of the holding table 31 by the lifting mechanism 40 is stopped (step S4). The distance sensor 35 measures the distance A (see FIG. 2) between the holding table 31 and the extension table 50 (step S5). The measured distance A is stored as a reference value in the reference value storage unit 91 of the control unit 90 (step S6). Thereafter, the sheet supplying step (see FIG. 5(a)) described above is performed (step S7), the liquid resin supplying step (see FIG. 5(b)) is performed (step S8), and the wafer holding step (see FIG. 5(c)) is performed (step S9). Subsequently, the extension step (see FIG. 5(d)) is performed (step S10), and the curing step (see FIG. 5(e)) is performed (step S11).

[0048] 3, in the process of curing the liquid resin r by irradiation with ultraviolet rays emitted from the multiple UV lamps 62, the holding table 31 and the extension table 50 are heated by the reaction heat generated when the liquid resin r is cured, and thermally expand by δ1 and δ2, respectively, as indicated by the dashed lines. Therefore, the distance B between the holding table 31 and the extension table 50 after thermal expansion is shortened by the sum of the thermal expansion amount δ1 of the holding table and the thermal expansion amount δ2 of the extension table 50 (δ1+δ2), and the following relationship is established between the distance A shown in FIG. 2 (the distance between the holding table 31 and the extension table 50 before heating) and the distance B shown in FIG. 3 and the thermal expansion amounts δ1 and δ2 of the holding table 31 and the extension table 50: AB=δ1+δ2 =ε …(1)

[0049] In the curing step (step S11), the holding table 31 and the extension table 50 are heated and thermally expanded, and the distance sensor 35 measures the distance B (see FIG. 3) between the holding table 31 and the extension table 50 (step S12). Then, the offset value setting unit 92 of the control unit 90 calculates the offset value ε of the holding table 31 using the above equation (1) (step S13). The offset value ε calculated by the offset value setting unit 92 is stored (step S14), thereby completing the calibration for determining the offset value ε of the holding table 31 (step S15).

[0050] As described above, once the offset value ε is calculated taking into account the amounts of thermal expansion δ1 and δ2 due to heating of the holding table 31 and the extension table 50 in the curing process, when the protective member is subsequently formed on the wafer W in the protective member forming apparatus 1, the height position of the holding table 31 in the holding process shown in Figure 5(c) is offset upward by the offset value ε from the preparation position.

[0051] 5(c), when the holding table 31 is lowered from a position offset upward by the offset value ε (=δ1+δ2) from the preparation position, the amount of pressure applied to the liquid resin r by the wafer W in the subsequent expansion step (see FIG. 5(d)) is reduced by the sum (=δ1+δ2) of the amounts of thermal expansion δ1 and δ2 of the holding table 31 and the extension table 50 in the curing step, and ultimately the liquid resin r is pressed and expanded by the wafer W by the same amount as when there is no thermal expansion of the holding table 31 and the extension table 50. This prevents the problem of excess liquid resin r being pressed and leaking from the outer periphery of the wafer W, which would gradually reduce the thickness of the protective member formed by the curing of the liquid resin r, and a protective member of a predetermined thickness is stably formed on the wafer W.

[0052] <Second Invention> Next, an embodiment of the protective member forming apparatus according to the second invention will be described. However, since the configuration of the protective member forming apparatus according to the present invention is the same as the configuration of the protective member forming apparatus 1 according to the first invention, illustrations and descriptions thereof will be omitted, and elements that are the same as those shown in the embodiment of the first invention will be described using the same symbols.

[0053] In an embodiment of the second invention, as shown in Figure 7, a distance sensor 35 is embedded in the outer periphery of the underside of the holding table 31, away from the sheet S, and the light emitted from this distance sensor 35 is directly irradiated onto the upper surface of the extension table 50 and reflected from said upper surface, so that the distance between the holding table 31 and the extension table 50 can be measured with high accuracy by this distance sensor 35.

[0054] Thus, this embodiment is characterized in that, while measuring the distance between the holding table 31 and the extension table 50 with the distance sensor 35, the lifting mechanism 40 raises and lowers the holding table 31 until the measured value reaches a preset value C. Here, the set value C of the distance between the holding table 31 and the extension table 50 is a value at which the wafer W held on the holding surface (lower surface) of the holding table 31 can press the liquid resin r by a predetermined amount to form a resin layer of a predetermined thickness, as shown in FIG. 7 , and this set value C is set by a setting unit 93 provided in the control unit 90 based on the thickness of the wafer W or sheet S. The set value C set by the setting unit 93 is stored in a set value storage unit 94 provided in the control unit 90.

[0055] The features of this embodiment will be described below with reference to the flowchart shown in FIG.

[0056] 5(c), in the holding step, the holding table 31, which holds the wafer W by suction on its lower holding surface, is lowered (moved) from the preparation position by the lifting mechanism 40 (step S21), and the distance between the holding table 31 and the extension table 50 is detected by the distance sensor 35 (step S22). Then, the control unit 90 determines whether the distance between the holding table 31 and the extension table 50 measured by the distance sensor 35 is equal to a predetermined set value C (step S23), and if the distance between the holding table 31 and the extension table 50 has not reached the set value C (step S23: No), the processing of steps S21 to S23 is repeated.

[0057] When the distance between the holding table 31 and the extension table 50 measured by the distance sensor 35 reaches a predetermined set value C (step S23: Yes), the lowering of the holding table 31 is stopped (step S24), and the process ends (step S25).

[0058] 5(c), while the distance sensor 35 measures the distance between the holding table 31 and the extension table 50, the lifting mechanism 40 lowers the holding table 31 from the state where the holding table 31 is in the preparation position until the measured value reaches the preset value C. Therefore, even if the holding table 31 and the extension table 50 thermally expand due to the heat of reaction of the liquid resin r in the previous curing step, the liquid resin r can always be spread by a predetermined amount by the wafer W in the expansion step regardless of the thermal expansion of the holding table 31 and the extension table 50. Therefore, the problem of excess liquid resin r being pressed out from the outer periphery of the wafer W and gradually thinning the thickness of the protective member formed by the curing of the liquid resin r does not occur, and a protective member of a predetermined thickness is stably formed on the wafer W.

[0059] Furthermore, according to the second invention, it is not necessary to obtain the offset value ε of the holding table 31 by the calibration carried out in the first invention, so that the protective member can be formed on the wafer W efficiently.

[0060] In each of the above-described embodiments of the first and second inventions, a configuration is adopted in which the holding table 31 is moved relative to the extension table 50, but the same effect as described above can be obtained even if a configuration is adopted in which the extension table 50 is moved relative to the holding table 31.

[0061] Furthermore, the present invention is not limited to the application of the above-described embodiments, and it goes without saying that various modifications are possible within the scope of the claims and the technical ideas described in the specification and drawings. [Explanation of symbols]

[0062] 1: protective member forming device, 2: temporary placement table, 3: wafer detection unit, 4: Sheet cutting table, 5: Sheet cutter, 6: Curing unit, 7: Sheet transport unit, 8: arm, 8a: clamping portion, 10: first conveying means, 11: base, 12: Robot hand, 13: Y-axis movement mechanism, 14: Guide rail, 15: Ball screw, 16: Motor, 20: Second conveying means, 21: Base, 22: Robot and hand, 23: X-axis movement mechanism, 24: guide rail, 25: ball screw, 30: wafer holder, 31: wafer holding table, 31a: suction hole, 32: suction path, 33: piping, 34: suction source, 35: distance sensor (distance measuring unit), 40: lifting mechanism, 41: guide rail, 42: lifting plate, 43: ball screw, 44: motor, 45: encoder (position detection unit), 50: extension table, 50a: suction groove, 60: curing unit, 61: case, 61A: Side wall, 61B: Bottom plate, 62: UV lamp, 63: Suction path, 64: Piping, 65: suction source, 70: dispenser, 80: resin tank, 81: resin nozzle, 82, 83: Piping, 90: Control unit, 91: Reference value storage unit, 92: Offset value setting unit, 93: setting unit, 94: setting value storage unit, 100: housing, 110: cassette storage unit, 111: first cassette, 112: second cassette, 120: base, 130: column, A, B, C: R: Sheet roll, r: Liquid resin, S: Sheet, V1, V2: On-off valve, W: wafer, δ1: thermal expansion amount of holding table, δ2: thermal expansion amount of extension table, ε: Offset value

Claims

1. an expansion table that expands the dripped liquid resin; a resin nozzle for dripping liquid resin; a holding table disposed above and facing the extension table; a lifting mechanism that lifts and lowers the holding table and the extension table relative to each other to expand the liquid resin; a curing unit for curing the expanded liquid resin; A protective member forming apparatus comprising: a position detection unit that detects a position of the extension table or the holding table moved by the lifting mechanism; a distance measuring unit that measures the distance between the extension table and the holding table; a reference value storage unit that moves the extension table or the holding table to a preset preparation position by the lifting mechanism, measures the distance between the extension table and the holding table by the distance measurement unit, and stores the measured value as a reference value; an offset value setting unit that moves the extension table or the holding table to the preparation position after forming the protective member and before spreading the liquid resin again, calculates a difference between the distance between the extension table and the holding table measured by the distance measuring unit and the reference value, and sets the difference as an offset value; a control unit that, when expanding the liquid resin, moves the extension table or the holding table by the lifting mechanism to a position obtained by adding the offset value to the preset preparation position to increase the distance between the extension table and the holding table, and then moves the extension table or the holding table closer to each other by a preset amount by the lifting mechanism, or moves the extension table or the holding table to the preset preparation position by the lifting mechanism, and then moves the extension table or the holding table closer to each other by an amount obtained by subtracting the offset value from the preset amount by the lifting mechanism; A protective member forming apparatus comprising:

2. an expansion table that expands the dripped liquid resin; a resin nozzle for dripping liquid resin; a holding table disposed above and facing the extension table; a lifting mechanism that lifts and lowers the holding table and the extension table relative to each other to expand the liquid resin; a curing unit for curing the expanded liquid resin; A protective member forming apparatus comprising: a distance measuring unit that measures the distance between the extension table and the holding table; a control unit that, while measuring the distance between the extension table and the holding table using the distance measurement unit, moves the extension table and the holding table relatively closer to each other using the lifting mechanism until the measured value reaches a preset value; A protective member forming apparatus comprising:

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