Apparatus for forming protective member and method for forming protective member

Abstract

To efficiently form a protective material on the entire surface of one side of a wafer in a short amount of time. [Solution] A method for forming a protective member to protect one entire surface of a wafer W by curing a liquid resin r spread over the entire surface of one surface of the wafer W includes: a liquid resin supply step of supplying liquid resin r between an expansion table 50 and a wafer W held by a holding table 31; a liquid resin spreading step of moving the expansion table 50 and the holding table 31 relative to each other in a direction toward proximity to spread the liquid resin r over the entire surface of one surface of the wafer W; an internal pressure removal step of moving the holding table 31 holding the wafer W and the expansion table 50 on which the liquid resin r has been spread relative to each other in a direction toward separation to remove the internal pressure of the liquid resin r; a wafer separation step of separating the wafer W from the holding table 31; and a curing step of applying an external stimulus to the liquid resin r spread on the expansion table 50 to cure the liquid resin r.

Description

[Technical Field]

[0001] The present invention relates to a protective member forming apparatus for forming a protective member on one side of a wafer, and a protective member forming method carried out using the same. [Background technology]

[0002] Sliced ​​wafers cut from cylindrical ingots have warping due to differences in the magnitude of processing distortion generated on both sides during cutting with cutting devices such as wire saws, and undulations on the surface of both sides. For this reason, a processing method has been implemented in which a protective member such as an ultraviolet-curing resin is formed on one side of the sliced ​​wafer to flatten its surface, the other side of the sliced ​​wafer is ground while the surface of this protective member is held on the holding surface of the chuck table to flatten that other side, the protective member is peeled off the sliced ​​wafer, and the other flat side is held on the holding surface of the chuck table to grind the other side of the sliced ​​wafer to create a flat surface without warping or undulations (see, for example, Patent Documents 1 and 2).

[0003] In the above processing method, a liquid resin is spread over the entire surface of one side of a sliced ​​wafer (hereinafter simply referred to as "wafer"), and a protective member is formed on one side of the wafer by curing this spread liquid resin. When spreading the liquid resin over the entire surface of one side of the wafer, a sheet is placed on an expansion table, the liquid resin is supplied onto this sheet, and a holding table, which is positioned above the expansion table and holds the wafer on its underside, is lowered to press the wafer against the liquid resin on the sheet, thereby spreading the liquid resin over the entire surface (entire underside) of one side of the wafer. If the liquid resin is an ultraviolet-curable resin, ultraviolet light (UV) is irradiated onto the spread ultraviolet-curable resin to cure it.

[0004] Incidentally, as disclosed in Patent Document 2, the compression pressure remaining in the expanded liquid resin is removed by separating the wafer from the holding table before the liquid resin, which has been spread over the entire surface of one side of the wafer, is cured. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2014-078550 [Patent Document 2] Japanese Patent Publication No. 2020-188230 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, removing the wafer from the holding table and releasing the residual compressive pressure in the liquid resin takes a certain amount of time, and the waiting time until the liquid resin hardens is long, which presents a problem in that the protective member cannot be formed efficiently in a short time. In addition, if the residual compressive pressure in the liquid resin is not sufficiently removed, the hardened resin has the force to warp the wafer, which can lead to insufficient removal of warping and undulation of the wafer held by the chuck table.

[0007] The present invention has been made in view of the above problems, and its object is to provide a protective member forming apparatus and a protective member forming method that can efficiently form a protective member on the entire surface of one side of a wafer in a short time. [Means for solving the problem]

[0008] The invention described in claim 1 is a protective member forming apparatus for forming a protective member that protects the entire surface of one surface of a wafer by curing a liquid resin spread over the entire surface of one surface of the wafer, comprising: an expansion table for spreading a liquid resin over the entire surface of one surface of a wafer on an expansion surface; a holding table for suction holding the wafer on a holding surface facing the expansion surface of the expansion table; a lifting mechanism for raising and lowering the holding table and the expansion table relative to each other; a liquid resin supply means for supplying a liquid resin between the expansion table and the wafer; a load detection unit for detecting a load acting on the holding table or the expansion table that holds the wafer when the liquid resin is being spread, or a distance detection unit for detecting the distance between the expansion table and the holding table; a control unit for driving and controlling the lifting mechanism, and an internal pressure removal means for removing the internal pressure of the liquid resin spread over the entire surface of one surface of the wafer to the same level as atmospheric pressure; and a curing means for curing the liquid resin from which the internal pressure has been removed by the internal pressure removal means.

[0009] The invention described in claim 2 is a method for forming a protective member that protects the entire surface of one side of a wafer by curing a liquid resin spread over the entire surface of one side of a wafer using the protective member forming apparatus described in claim 1, and is characterized by comprising: a liquid resin supply step of supplying a liquid resin between the expansion table and a wafer held on the holding table; an expansion step of relatively moving the expansion table and the holding table toward each other using the lifting mechanism to spread the liquid resin over the entire surface of one side of a wafer; an internal pressure removal step of removing the internal pressure of the liquid resin spread over the entire surface of one side of the wafer in the expansion step using the internal pressure removal means; a wafer separation step of separating the wafer from the holding table after the internal pressure removal step; and a curing step of curing the liquid resin spread over the entire surface of one side of a wafer by applying an external stimulus.

[0010] The invention described in claim 3 is characterized in that, in the invention described in claim 2, in the internal pressure removal step, after the liquid resin expansion step, the control unit drives and controls the lifting mechanism to move the expansion table and the holding table relative to each other in a direction away from each other until the load detected by the load detection unit reaches a preset value.

[0011] The invention described in claim 4 is characterized in that, in the invention described in claim 2, in the internal pressure removal step, after the liquid resin expansion step, the control unit drives and controls the lifting mechanism to move the expansion table and the holding table relative to each other in a direction away from each other until the distance detected by the distance detection unit reaches a preset value. [Effects of the Invention]

[0012] According to the protective member forming method of claim 2, which is carried out using the protective member forming apparatus of claim 1, the compression pressure inside the liquid resin in the expansion step can be removed in a shorter time than conventional methods by performing the subsequent internal pressure removal step. As a result, the waiting time until the liquid resin hardens in the subsequent curing step is shortened, and the protective member can be formed efficiently in a short time.

[0013] According to the invention described in claim 3, since the load detected by the load detection unit can be converted into a change in the internal pressure of the liquid resin, the internal pressure of the liquid resin can be reliably removed by moving the holding table and the expansion table relative to each other in a direction away from each other until the load detected by the load detection unit reaches a set value.

[0014] According to the invention described in claim 4, when forming protective members continuously on multiple wafers of uniform thickness, the time required to remove the pressure inside the liquid resin can be further reduced by moving the holding table and the expansion table relative to each other in a direction away from each other until the distance detected by the distance detection unit reaches a set value. [Brief explanation of the drawing]

[0015] [Figure 1] It is a perspective view of a protective member forming apparatus according to the present invention. [Figure 2A] (a) to (d) are longitudinal sectional views (part 1) showing the method for forming a protective member according to the first embodiment of the present invention in the order of its steps. [Figure 2B] (e) to (g) are longitudinal sectional views (part 2) showing the method for forming a protective member according to the first embodiment of the present invention in the order of its steps. [Figure 3] It is a diagram showing the change over time of the internal pressure of the liquid resin for a wafer in the method for forming a protective member according to the first embodiment of the present invention. [Figure 4A] (a) to (d) are longitudinal sectional views (part 1) showing the method for forming a protective member according to the second embodiment of the present invention in the order of its steps. [Figure 4B] (e) to (g) are longitudinal sectional views (part 2) showing the method for forming a protective member according to the second embodiment of the present invention in the order of its steps. [Figure 5] It is a diagram showing the change over time of the distance between a holding table and an expansion table in the method for forming a protective member according to the second embodiment of the present invention. [Figure 6] It is a longitudinal sectional view showing a state in which the other surface of a wafer having a protective member formed on one surface is being ground. [Figure 7] (a) to (c) are side sectional views showing a method for peeling a protective member. [Figure 8] It is a longitudinal sectional view showing a state in which one surface of a wafer from which a protective member has been peeled is being ground.

Mode for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described based on the accompanying drawings.

[0017] [Configuration of Protective Member Forming Apparatus] First, the configuration of a protective member forming apparatus according to the present invention will be described based on FIG. 1. In the following description, the directions of the arrows shown in FIG. 1 are taken as the X-axis direction (left - right direction), Y-axis direction (front - back direction), and Z-axis direction (up - down direction), respectively.

[0018] The protective member forming apparatus 1 shown in Figure 1 is an apparatus for forming a protective member P on one side (the bottom surface in Figure 1) of a disc-shaped wafer W, the protective member P consisting of a sheet S and a resin R formed from a hardened liquid resin r on one side, and comprises a housing 100 and a cassette housing 110 arranged along the X-axis. Here, the cassette housing 110 houses a first cassette 111 and a second cassette 112 along the Y-axis, with the first cassette 111 housing multiple wafers W before the protective member P is formed, and the second cassette 112 housing multiple wafers W after the protective member P is formed. The wafer W is a disc-shaped slice wafer cut from a cylindrical ingot of single-crystal silicon or the like.

[0019] Furthermore, the interior of the housing 100 houses, in order from the -X axis (left side), components such as the first transport means 10, the second transport means 20, the temporary storage table 2, the sheet cutting table 4, the wafer holding section 30, the lifting mechanism 40, the expansion table 50, the curing means 60, the liquid resin supply means 70, the sheet transport section 7, and the internal pressure removal means 80 (see Figures 2A(c) to (g)). The configuration of each component will be described in order below.

[0020] (First transport means) The first transport means 10 is responsible for taking out a wafer W from the first cassette 111 and transporting the wafer W to the temporary storage table 2, as well as receiving the wafer W with the protective member P formed on it from the sheet cutting table 4 and storing it in the second cassette 112. It includes a robot hand 12 mounted on a base 11 and a Y-axis movement mechanism 13 that moves the base 11 together with the robot hand 12 in the Y-axis direction.

[0021] Here, the Y-axis movement mechanism 13 consists of a pair of guide rails 14 arranged parallel to each other along the Y-axis direction, a rotatable ball screw 15 positioned between these guide rails 14 along the Y-axis direction, and a motor 16 for rotating the ball screw 15 in forward and reverse directions. The ball screw 15 is screwed into a nut member (not shown) protruding from the lower surface of the base 11. Therefore, when the motor 16 is activated to rotate the ball screw 15 in forward and reverse directions, the base 11, on which the nut member (not shown) through which the ball screw 15 is screwed is located, moves along the Y-axis direction together with the robot hand 12.

[0022] (Second transport means) The second transport means 20 receives the wafer W from the temporary storage table 2 and transports the wafer W to the wafer holding unit 30, and also receives the wafer W on which the protective member P is formed from the expansion table 50 and transports it to the sheet cutting table 4. It includes 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.

[0023] Here, the X-axis movement mechanism 23 consists of a pair of guide rails 24 arranged parallel to each other along the X-axis direction, a rotatable ball screw 25 positioned between these guide rails 24 along the X-axis direction, and a motor (not shown) for reversing the ball screw 25 forward and backward. The ball screw 25 is screwed into a nut member (not shown) protruding from the lower surface of the base 21. Therefore, by activating the motor (not shown) to reverse the ball screw 25 forward and backward, the base 21, on which the nut member (not shown) into which the ball screw 25 is screwed, moves along the X-axis direction together with the robot hand 22.

[0024] (Temporary table) The temporary storage table 2 is used to temporarily place wafers W that have been removed from the first cassette 111 by the robot hand 12 of the first transport means 10. The wafers W temporarily placed on the temporary storage table 2 have their center position and orientation optically detected by the wafer detection unit 3.

[0025] (Sheet cutting table) The sheet cutting table 4 is positioned below the temporary placement table 2 and is used to place the wafer W on which the protective member P is formed. The sheet S attached to the wafer W is cut along the outer circumference of the wafer W by the sheet cutter 5.

[0026] (Wafer holding section) The wafer holding section 30 includes a disc-shaped holding table 31, and as shown in Figure 2A(c), a circular recess 31A opening downwards is formed in the center of the holding table 31. A disc-shaped holding plate 32 is housed within this circular recess 31A, and this holding plate 32 is floating-supported by three load detection units, which are load sensors 81 (see Figure 1), arranged at equal angular pitches (120° pitches) in the circumferential direction. Each load sensor 81 is composed of a load cell or the like.

[0027] Here, the lower surface of the retaining plate 32 constitutes a retaining surface, and as shown in Figure 2A(c), a plurality of suction holes 32a are opened in this retaining surface. These suction holes 32a are connected to the suction source 35 via piping 34 connected to the suction passage 33. A shut-off valve V1 is provided in the piping 34.

[0028] (Lifting mechanism) The lifting mechanism 40 is a mechanism for raising and lowering the wafer holding section 30, which includes a holding table 31 that holds a wafer W, in the Z-axis direction, and is installed on a column 130 that stands vertically on a base 120. Specifically, the lifting mechanism 40 includes a pair of guide rails 41 mounted parallel to the Z-axis direction of the column 130, a lifting plate 42 that moves up and down in the Z-axis direction along these guide rails 41, a rotatable ball screw 43 positioned vertically between the pair of guide rails 41, a motor 44 that rotates the ball screw 43 in forward and reverse directions, and an encoder 45 that detects the rotational speed, rotational velocity, and rotational direction of the motor 44, and the holding table 31 of the wafer holding section 30 is attached to the lifting plate 42.

[0029] Although not shown in the figures, a nut is attached to the back of the lifting plate 42, and a ball screw 43 is screwed into this nut. The motor 44 and encoder 45 are electrically connected to the control unit 82, which will be described later, as shown in Figures 2A(c) to (g). When a detection signal is transmitted from the encoder 45 to the control unit 82, the control unit 82 drives the motor 44 based on the received detection signal.

[0030] Therefore, when the motor 44 is started and the ball screw 43 is rotated 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 a pair of guide rails 41 together with the wafer holding unit 30 and the wafer W that is held by attraction to the holding table 31 (holding plate 32) of the wafer holding unit 30, and the height position of the holding table 31 is detected by the encoder 45.

[0031] (Extended Table) The extension table 50, which is mounted on the base 120, is a disc-shaped member made of a translucent material such as quartz glass, and its upper surface forms a flat extension surface on which the sheet S is placed. A ring-shaped suction groove 50a is formed around the extension surface of the extension table 50.

[0032] (curing means) The curing means 60 is positioned below the expansion table 50 and, as described later, cures the liquid resin r (see Figure 2A(b)), which is an ultraviolet-curable resin supplied onto a sheet S placed on the expansion table 50, by irradiating it with ultraviolet (UV) light as an external stimulus. As shown in Figure 2A, the curing means 60 includes a case 61 whose top surface is closed by the expansion table 50. Here, the case 61 has side walls 61A and a bottom plate 61B, and a plurality of UV lamps 62 that irradiate the liquid resin r with ultraviolet light are housed in the space formed by these side walls 61A, the bottom plate 61B and the expansion table 50. If the liquid resin r is a thermosetting type, a heater (not shown) is provided on the expansion table 50 or the holding table 31. The heat from the heater provided on the holding table 31 acts on the liquid resin r via the wafer W.

[0033] Furthermore, as shown in Figure 2A(a), four suction holes 61a (only two are shown in Figure 2A(a)) are opened on the upper surface of the side wall 61A of the case 61. These suction holes 61a and the ring-shaped suction groove 50a formed around the expansion table 50 are connected to the suction source 65 via piping 64 connected to a suction passage 63 formed in the side wall 61A of the case 61. A shut-off valve V2 is provided in the piping 64.

[0034] (Liquid resin supply means) The liquid resin supply means 70, as described later, supplies a predetermined amount of liquid resin r toward the center of the sheet S placed on the extension table 50, and includes a dispenser 71 located on the side of the base 120 and a resin tank 72 for storing the liquid resin. Here, the resin tank 72 is installed inside the base 120, and a resin pipe 73 extending from its side is connected to the dispenser 71. The liquid resin supply means 70 may also have a function to adhere a predetermined amount of liquid resin r to the center of the wafer W held on the holding table 31.

[0035] Here, the dispenser 71 performs the function of supplying a predetermined amount of liquid resin r stored in the resin tank 72 to the resin supply nozzle 75 and then supplying it to the sheet S.

[0036] (Sheet transport section) The sheet transport unit 7 pulls out the sheet S from the sheet roll SR, in which the sheet S is wound in a roll shape, and transports it to the expansion table 50. It is equipped with a clamp portion 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 while the clamp portion 8a is gripping the end of the sheet S wound on the sheet roll SR, the sheet S is pulled out from the sheet roll SR and held on the upper surface of the expansion table 50, and the sheet S held on the expansion table 50 is cut to an appropriate length. The sheet S is made of a light-transmitting material such as polyethylene terephthalate (PET), which transmits ultraviolet light. However, if the liquid resin r is thermosetting, the sheet S does not have to be made of a light-transmitting material. The sheet S is placed to facilitate the separation of the protective member P formed by curing the liquid resin r from the expansion table 50, but if the separation of the protective member P from the expansion table 50 is easy, the sheet S may not be used.

[0037] (Means for relieving internal pressure) As described later, the internal pressure removal means 80 works by supplying a predetermined amount of liquid resin r onto the sheet S on the expansion table 50, then lowering the holding table 31 with the lifting mechanism 40, expanding the liquid resin r with the wafer W held on the holding surface of the holding plate 32 provided on the holding table 31, and then removing the compression pressure remaining in the liquid resin r. This internal pressure removal means 80 is composed of three load sensors 81 that constitute a load detection unit and a control unit 82 that drives and controls the lifting mechanism 40 based on the load values ​​(compression pressure remaining in the liquid resin r) detected by these load sensors 81, but the details of its operation will be described later.

[0038] Furthermore, the holding plate 32, which holds the wafer W by suction on the holding surface, is floating-supported (freely supported) so that no frictional resistance force is generated between it and the holding table 31. For this reason, the load applied to the holding plate 32 when the liquid resin r is being spread is detected with high accuracy by three load sensors 81. In this embodiment, the sum of the loads detected by each of the three load sensors 81 becomes the compressive pressure applied to the liquid resin r.

[0039] [Method for forming protective members] Next, an embodiment of the protective member forming method according to the present invention, which is carried out using the protective member forming apparatus 1 configured as described above, will be explained.

[0040] <First Embodiment> In the protective member forming method according to the first embodiment, 1) Sheet supply process: 2) Liquid resin supply process: 3) Wafer holding process: 4) Expansion process: 5) Internal pressure relief process: 6) Wafer separation process: 7)Curing process: By carrying out these steps sequentially, a protective member P is formed on the entire surface of one side of the wafer W. Each step will be explained below.

[0041] 1) Sheet supply process: In the sheet supply process, as shown in Figure 2A(a), a thin, rectangular, transparent sheet S is supplied onto an expansion table 50 provided on the upper surface of the case 61 of the curing means 60. That is, in the sheet transport section 7 shown in Figure 1, one end of the sheet S wound around the sheet roll SR is gripped by the clamp portion 8a of the arm 8, and as the arm 8 moves in the -X axis direction in Figure 1, the sheet S is supplied and set onto the expansion table 50. From this state, when the on / off valve V2 opens, the negative pressure generated in the suction source 65 is transmitted through the piping 64 and suction passage 63 to the suction groove 50a and suction hole 61a that open on the upper surface of the expansion table 50, and the sheet S is attracted and held on the expansion surface of the expansion table 50 by this negative pressure.

[0042] 2) Liquid resin supply process: In the liquid resin supply process, the liquid resin r stored in the resin tank 72 shown in Figure 1 is drawn into the dispenser 71 via the resin piping 73. A predetermined amount of liquid resin r is then supplied from the dispenser 71 to the resin supply nozzle 75 via the resin piping 74. As shown in Figure 1A(b), the predetermined amount of liquid resin r is supplied from the resin supply nozzle 75 to the center of the upper surface of the sheet S held on the expanded surface of the expanded table 50.

[0043] 3) Wafer holding process: In the wafer holding process, one wafer W is removed from the first cassette 111 by the first transport means 10 shown in Figure 1, and the removed wafer W is temporarily placed on the temporary storage table 2. Then, the center position and orientation of the wafer W temporarily placed on the temporary storage table 2 are optically detected by the wafer detection unit 3. The wafer W whose center position and orientation have been detected in this way is then transported to the wafer holding unit 30 by the second transport means 20, and is held by suction on the holding surface of the holding plate 32 of the wafer holding unit 30. That is, when the on / off valve V1 shown in Figure 2A(c) opens, the negative pressure generated in the suction source 35 is transmitted through the piping 34 and suction passage 33 to the multiple suction holes 32a that open on the holding surface of the holding plate 32, and the wafer W is held by suction on the holding surface of the holding plate 32 due to this negative pressure.

[0044] 4) Expansion process: As described above, when the wafer W is held by suction on the holding surface of the holding plate 32, the holding table 31 is lowered by the lifting mechanism 40 together with the wafer W held on the holding plate 32, and as shown in Figure 2A(d), the liquid resin r supplied onto the sheet S is pushed and expanded by the wafer W.

[0045] Here, Figure 3 shows the time change of the internal pressure F of the liquid resin detected by the load sensor 81. As shown in the figure, from time t=0 when the wafer W comes into contact with the liquid resin r, as the liquid resin r is expanded by the wafer W, a compressive pressure F1 is generated in the liquid resin r, and this compressive pressure F1 gradually increases along the straight line A in Figure 3 as time t progresses. Since this compressive pressure F1 of the liquid resin r is received by each load sensor 81 via the wafer W and the holding plate 32, the load detected by each load sensor 81 is transmitted to the control unit 82, and the control unit 82 recognizes the sum of the loads as the internal pressure F (compressive pressure F1) of the liquid resin r.

[0046] Then, at time t1, when the holding table 31 that holds the wafer W is lowered by a predetermined amount by the lifting mechanism 40, and the liquid resin r is spread over the entire surface of one side of the wafer W, the internal pressure F of the liquid resin r is equal to the value of the compression pressure F1, as shown by point a in Figure 3. Therefore, at time t1, when the liquid resin r is spread over the entire surface of one side of the wafer W during the expansion process, the compression pressure F1 remains in the liquid resin r.

[0047] 5) Internal pressure relief process: The internal pressure removal process is a process to remove the compression pressure F1 remaining in the liquid resin r in the preceding expansion process. When the load sensor 81 detects the compression pressure F1 at time t1, the control unit 82 drives and controls the lifting mechanism 40 to raise the holding table 31 holding the wafer W by a predetermined amount, as shown in Figure 2B(e). Specifically, when the internal pressure F of the liquid resin detected by the load sensor 81 is a preset value F, the control unit 82 controls the internal pressure F of the liquid resin. SThe holding table 31, which holds the wafer W, is raised by a predetermined amount until it reaches a certain point.

[0048] In other words, in this internal pressure removal process, the compression pressure F1 at point a along the straight line B in Figure 3, which remains in the liquid resin r in the preceding expansion process, is set to the set value F at point b. S The pressure decreases to the set value F, and the compression pressure F1 remaining in the liquid resin r is removed, and the liquid resin r is also reduced to the set value F S A small tensile force acts upon it.

[0049] 6) Wafer separation process: The wafer separation process is a process of separating the wafer W, which has liquid resin r spread over the entire surface of one side, from the holding table 31. In this wafer separation process, the on / off valve V1 is closed, releasing the suction holding of the wafer W to the holding table 31 (holding plate 32) by the negative pressure generated by the suction source 35, and the lifting mechanism 40 is activated by the control unit 82, causing the holding table 31 to rise and separate from the wafer W. As shown in Figure 2B(f), the wafer W with liquid resin r spread over one side remains on the expansion table 50 side.

[0050] As described above, when the wafer W is separated from the holding table 31 and the holding table 31 is raised in the wafer separation process, the set value F acting on the liquid resin r is reduced, as shown in Figure 3. S The tensile force is removed, and the internal pressure of the liquid resin r becomes equal to atmospheric pressure (external pressure). In other words, the internal pressure F of the liquid resin r rises along the straight line C from point b to point c in Figure 3, becomes 0 at time t3, and thereafter the state of internal pressure F=0 of the liquid resin is maintained (see straight line D in Figure 3). That is, by performing the internal pressure removal process and the wafer separation process, the compressive pressure F1 generated inside the liquid resin r due to the expansion of the liquid resin r becomes equal to atmospheric pressure.

[0051] In the above method, a tensile force is temporarily applied to the liquid resin r before adjusting the internal pressure F of the liquid resin to equal atmospheric pressure. However, the compressive pressure F1 may be reduced over time along the straight line B, and the holding table 31 may be moved away from the wafer W when the value of the load sensor 81 becomes 0 (zero), that is, when the internal pressure F of the liquid resin becomes 0 (zero).

[0052] 7)Curing process: The curing process involves curing a liquid resin r that has been spread over the entire surface of one side of the wafer W. In this curing process, as shown in Figure 2B(g), the holding table 31 is separated from the wafer W, and a plurality of UV lamps 62 provided in the curing means 60 are turned on. Then, ultraviolet light (UV) emitted upward from each UV lamp 62 passes through the transparent, light-transmitting expansion table 50 and sheet S and irradiates the liquid resin r, causing the liquid resin r to harden due to the ultraviolet light. As a result of this hardening of the liquid resin r, a protective member P consisting of the sheet S and the hardened resin R is formed on one side of the wafer W, as shown in Figure 7(a).

[0053] After the above process, the wafer W, on which the protective member P has been formed on one side, is transported to the sheet cutting table 4 by the second transport means 20 shown in Figure 1. On the sheet cutting table 4, the sheet S attached to the wafer W is cut in a circular shape along the outer circumference of the wafer W by the sheet cutter 5. The wafer W, with the sheet S cut in this way, is then transported to the second cassette 112 by the first transport means 10 and placed in the second cassette 112, thus completing the series of processes for forming the protective member P on the wafer W.

[0054] As described above, in the protective member forming method according to this embodiment, the compression pressure F1 remaining in the liquid resin r in the preceding expansion step is removed in the subsequent internal pressure removal step. Specifically, in the expansion step, the liquid resin r is pressed against the wafer W and expanded over the entire surface of one side of the wafer W, and then the load F detected by the load sensor 81 reaches a set value F SThe holding table 31, which holds the wafer W, is raised away from the expansion table 50 until the wafer W is fully expanded. As a result, the compression pressure F1 remaining in the liquid resin r during the expansion process is removed in a short time. Therefore, the waiting time until the liquid resin r hardens in the next curing process is shortened, and the protective member P can be formed efficiently in a short time.

[0055] <Second Embodiment> Next, a second embodiment of the protective member forming method according to the present invention will be described below with reference to Figures 4A, 4B, and 5.

[0056] In the protective member formation method according to this embodiment, similar to the protective member formation method according to the first embodiment, the protective member P is formed on the entire surface of one side of the wafer W by sequentially performing the following steps in this order: 1) sheet supply step, 2) liquid resin supply step, 3) wafer holding step, 4) expansion step, 5) internal pressure removal step, 6) wafer separation step, and 7) curing step. Each step will be described below.

[0057] 1) Sheet supply process: In the sheet supply process, as shown in Figure 4A(a), a thin, rectangular, transparent sheet S is supplied onto an expansion table 50 provided on the upper surface of the case 61 of the curing means 60. However, this sheet expansion process is the same as the sheet expansion process in the first embodiment shown in Figure 2A(a), so a detailed explanation of it will be omitted.

[0058] 2) Liquid resin supply process: In the liquid resin supply process, as shown in Figure 4A(b), a predetermined amount of liquid resin r is supplied from the resin supply nozzle 75 to the center of the upper surface of the sheet S held on the expanded surface of the expanded table 50. However, this liquid resin supply process is the same as the liquid resin supply process in the first embodiment shown in Figure 2A(b), so a detailed explanation of it will be omitted.

[0059] 3) Wafer holding process: In the wafer holding process, as shown in Figure 4A(c), the wafer W is held by suction on the holding surface of the holding table 31. That is, when the on / off valve V1 opens, the negative pressure generated in the suction source 35 acts on the holding surface of the holding table 31 via the suction passage 33, and the wafer W is held by suction on the holding surface of the holding table 31 due to this negative pressure.

[0060] Here, distance sensors 83 and 84 are provided at the lower part of the holding table 31 and the upper part of the extension table 50, respectively, which are distance detection units that optically and non-contact measure the vertical distance H between the holding surface of the holding table 31 and the extension surface (upper surface) of the extension table 50. In the wafer holding process, the distance H between the holding table 31 and the extension table 50 is set to H1 (see Figures 4A(c) and 5). The distance sensors 83 and 84 are electrically connected to the control unit 82, and these distance sensors 83 and 84 and the control unit 82 constitute an internal pressure removal means that removes the compression pressure remaining in the liquid resin r in the internal pressure removal process described later. In addition to optical sensors, the distance sensors 83 and 84 may also be ultrasonic sensors, back pressure sensors, contact-type height gauges, etc. Furthermore, the distance H may be detected using an encoder 45 that detects the height position of the holding table 31 as the distance detection unit.

[0061] 4) Expansion process: As described above, when the wafer W is held by suction on the holding surface of the holding plate 32, the holding table 31 holding the wafer W is lowered by the lifting mechanism 40, and as shown in Figure 4A(d), the liquid resin r supplied onto the sheet S is pushed and expanded by the wafer W.

[0062] Here, Figure 5 shows the time change of the distance H between the holding table 31 and the expansion table 50 as detected by distance sensors 83 and 84. As shown in the figure, when the holding table 31 and the wafer W are lowered by the lifting mechanism 40 from time t=0, when the wafer W is held in the holding table 31 and the distance H between the holding table 31 and the expansion table 50 is maintained at H1, the distance H between the holding table 31 and the expansion table 50 as detected by distance sensors 83 and 84 decreases along the straight line K shown in Figure 5 as time t progresses.

[0063] Then, at time t1, when the holding table 31, which holds the wafer W, has been lowered by a predetermined amount by the lifting mechanism 40, and the liquid resin r has been spread over the entire surface of one side of the wafer W, the distance H between the holding table 31 and the expansion table 50 detected by the distance sensors 83 and 84, as shown by point d in Figure 5, is H2 (see Figures 4A(d) and 5). At this time, at time t1, when the liquid resin r has been spread over the entire surface of one side of the wafer W during the expansion process, compressive pressure remains in the liquid resin r.

[0064] 5) Internal pressure relief process: The internal pressure removal process is a process to remove the compression pressure remaining in the liquid resin r in the preceding expansion process. When the distance H2 is detected by the distance sensors 83 and 84 at time t1, the control unit 82 drives and controls the lifting mechanism 40 to raise the holding table 31 together with the wafer W held therein by a predetermined amount, as shown in Figure 4B(e). Specifically, when the distance H detected by the distance sensors 83 and 84 is a preset value H2, the control unit 82 controls the lifting mechanism 40 to raise the holding table 31 together with the wafer W held therein by a predetermined amount. S The holding table 31 is raised by a predetermined amount together with the wafer W until time t2 reaches [a certain point]. At this time, the distance H between the holding table 31 and the expansion table 50 increases along the straight line L shown in Figure 5, from the value H2 at point d to the set value H at point e. S It increases to this value. Here, the set value of distance H is H SIt is set to a value that is necessary and sufficient to remove the compression pressure remaining in the liquid resin r. Therefore, in this internal pressure removal step, the compression pressure remaining in the liquid resin r in the expansion step, which is the previous step, is removed.

[0065] 6) Wafer separation step: The wafer separation step is a step of separating the wafer W with the liquid resin r expanded over the entire one surface thereof from the holding table 31. In this wafer separation step, the on-off valve V1 is closed and the suction holding of the wafer W to the holding table 31 by the negative pressure generated by the suction source 35 is released. At the same time, the lifting mechanism 40 is activated by the control unit 82 and the holding table 31 rises and separates from the wafer W. As shown in FIG. 4B(f), the wafer W with the liquid resin r expanded on one surface remains on the expansion table 50 side.

[0066] When the holding table 31 rises in this wafer separation step, the distance H detected by the distance sensors 83 and 84 increases along the straight line M shown in FIG. 5, from the set value H at the point e S to the value H3 at the point f (time t3), and thereafter the constant value H3 is maintained (see the horizontal straight line N in FIG. 5).

[0067] 7) Curing step: The curing step is a step of curing the liquid resin r expanded over the entire one surface of the wafer W. In this curing step, as shown in FIG. 4B(g), with the holding table 31 separated from the wafer W, a plurality of UV lamps 62 provided in the curing means 60 are lit. Then, ultraviolet rays (UV) emitted upward from each UV lamp 62 pass through the transparent light-transmissive expansion table 50 and the sheet S and irradiate the liquid resin r, and the liquid resin r is cured by the ultraviolet rays. By curing the liquid resin r in this way, as shown in FIG. 7(a), a protective member P composed of the sheet S and the cured resin R is formed on one surface of the wafer W.

[0068] After the above process, the wafer W, on which the protective member P has been formed on one side, is transported to the sheet cutting table 4 by the second transport means 20 shown in Figure 1. On the sheet cutting table 4, the sheet S attached to the wafer W is cut in a circular shape along the outer circumference of the wafer W by the sheet cutter 5. The wafer W, with the sheet S cut in this way, is then transported to the second cassette 112 by the first transport means 10 and placed in the second cassette 112, thus completing the series of processes for forming the protective member P on the wafer W.

[0069] As described above, in the protective member forming method according to this embodiment, the compression pressure remaining in the liquid resin r in the preceding expansion step is removed in the subsequent internal pressure removal step. Specifically, in the expansion step, the liquid resin r is pressed against the wafer W and expanded over the entire surface of one side of the wafer W, and then the distance H detected by the distance sensors 83 and 84 reaches a set value H. S The holding table 31, which holds the wafer W, is raised away from the expansion table 50 until the wafer W is fully expanded. As a result, the compressive pressure remaining in the liquid resin r during the expansion process is removed in a short time. Therefore, the waiting time until the liquid resin r hardens in the next curing process is shortened, and the protective member P can be formed efficiently in a short time.

[0070] Incidentally, once a protective member P is formed on one surface of a wafer W by the protective member formation method according to the first or second embodiment, the other surface of the wafer W (the surface on which the protective member P is not formed) is ground by the grinding wheel 125b shown in Figure 6 of the grinding apparatus. Here, in Figure 6, 123 is a spindle that is rotationally driven by a spindle motor (not shown), and a disc-shaped mount 124 is attached to the lower end of this spindle 123. A grinding wheel 125 is detachably attached to the lower surface of the mount 124, and this grinding wheel 125 is constructed by attaching a plurality of annularly arranged grinding wheels 125b to the lower surface of a disc-shaped base 125a. The grinding unit including the grinding wheel 125 can be raised and lowered vertically by a lifting mechanism 140.

[0071] Then, when grinding the other side (the side without the protective member P) of the wafer W, which has a protective member P formed on one side, the wafer W is held by suction on the holding surface of the chuck table 200 with the flat protective member P facing downwards, as shown in Figure 6. Here, a porous disc-shaped porous member 200A is incorporated into the upper center of the chuck table 200. This porous member 200A is connected to a suction source 202 via a pipe 201, and an on / off valve V3 is provided in the pipe 201.

[0072] Therefore, when the on / off valve V3 is opened and the porous member 200A is connected to the suction source 202, a negative pressure is generated in the porous member 200A, and the wafer W is attracted by this negative pressure and held in place on the holding surface (upper surface) of the chuck table 200 with the sheet S (protective member P) facing downwards. The chuck table 200 is rotatable about a vertical rotation axis CL1 and is driven to rotate at a predetermined speed in the direction of the arrow in Figure 6 by a drive source (not shown).

[0073] Furthermore, the grinding wheel 125 is driven to rotate at a predetermined speed around the rotation axis CL2 of the spindle 123 by a spindle motor (not shown) in the direction of the arrow shown (the same direction as the rotation direction of the chuck table 200), and is raised and lowered vertically by a lifting mechanism 140.

[0074] In the grinding of the wafer W, the chuck table 200 is driven to rotate at a predetermined speed in the direction of the arrow shown, with respect to the rotation axis CL1, by a rotation mechanism (not shown), and the grinding wheel 125 is driven to rotate at a predetermined speed with respect to the rotation axis CL2, by a spindle motor (not shown), with the circumscribed circle of the grinding wheel 125b passing through the center of the wafer W.

[0075] When the grinding wheel 125 is lowered by the lifting mechanism 140 by a predetermined amount of grinding from the above state, the other surface of the wafer W where the protective member P is not formed (the upper surface in Figure 6) is ground by the grinding wheel 125b. As a result, any warping or undulation remaining on the other surface of the wafer W is removed, and the other surface of the wafer W (the upper surface in Figure 6) becomes a flat plane. During the grinding process of the wafer W, grinding water (pure water) is supplied to the contact point (processing point) between the wafer W and the grinding wheel 125b. The frictional heat generated at the processing point is removed by the grinding water, suppressing the temperature rise at the processing point, and the grinding debris generated by grinding is washed away by the grinding water.

[0076] As described above, once the other surface of the wafer W is ground to a flat surface, the protective member P formed on one surface of the wafer W is peeled off from the wafer W together with the sheet S in the following manner.

[0077] In other words, as a method for peeling the protective member P from the wafer W together with the sheet S, this embodiment employs a method of applying force in a direction that makes it easier to peel off the protective member P. Specifically, as shown in Figure 7(a), the end of the sheet S of the protective member P formed on one side of the wafer W (the lower surface in Figure 7(a)) that has been ground by grinding is gripped by a clamper 150 as shown in Figure 7(b), and the clamper 150 is pulled in the direction of the arrow (diagonally downward) that makes it easier to peel off the protective member P, thereby peeling the protective member P from the wafer W. Figure 7(c) shows the wafer W from which the protective member P has been peeled off in this way, but warping and undulation still remain on the side of this wafer W from which the protective member P has been peeled off (the lower surface in Figure 7(c)).

[0078] As described above, once the protective member P is peeled off the wafer W together with the sheet S, the wafer W is held in place by suction on the holding surface of the chuck table 200 with the other already ground flat surface facing downwards, as shown in Figure 8. Then, the surface of the wafer W from which the protective member P was peeled off is ground by the grinding wheel 125b in the same manner as described above.

[0079] Specifically, as shown in Figure 8, the chuck table 200 is driven to rotate at a predetermined speed in the direction of the arrow shown, with respect to the rotation axis CL1, by a rotation mechanism (not shown), together with the wafer W, and the grinding wheel 125 is driven to rotate at a predetermined speed with respect to the rotation axis CL2, with the circumscribed circle of the grinding wheel 125b passing through the center of the wafer W, by a spindle motor (not shown).

[0080] Then, when the grinding wheel 125 is lowered by the lifting mechanism 140 by a predetermined amount of grinding, one side of the wafer W where the protective member P was formed (the upper surface in Figure 8) is ground by the grinding wheel 125b. As a result, any warping or undulation remaining on one side of the wafer W is removed, and both sides of the wafer W are ground to create a flat surface. In this grinding process, grinding water (pure water) is supplied to the contact point (processing point) between the wafer W and the grinding wheel 125b. The frictional heat generated at the processing point is removed by the grinding water, suppressing the temperature rise at the processing point, and the grinding debris generated by the grinding is washed away by the grinding water.

[0081] In the above embodiment, a process of manufacturing a wafer from a sliced ​​wafer sliced ​​from an ingot by grinding both sides of the wafer was described. However, the present invention may also be applied when grinding only one side of the wafer. For example, the present invention may be applied when grinding the back surface of a wafer having irregularities on its surface, such as when a plurality of device chips are placed on the surface.

[0082] In the above embodiment, the holding table 31 is configured to be raised and lowered relative to the extension table 50, but the same effect can be obtained by adopting the opposite configuration, where the extension table 50 is raised and lowered relative to the holding table 31. Furthermore, the holding table 31 and the extension table 50 may be arranged in reverse.

[0083] Furthermore, the present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the technical idea described in the claims, specification, and drawings. [Explanation of Symbols]

[0084] 1: Protective member forming apparatus, 2: Temporary placement table, 3: Wafer detection unit, 4: Sheet cutting table, 5: Sheet cutter, 7: Sheet transport unit, 8: Arm, 8a: Clamp section, 10: First transport means, 11: Base, 12: Robot hand, 13: Y-axis movement mechanism, 14: Guide rail, 15: Ball screw, 16: Motor, 20: Second transport means, 21: Base, 22: Robot hand, 23: X-axis movement mechanism, 24: Guide rail, 25: Ball screw, 30: Wafer holder, 31: Holding table, 31A: Circular recess, 31a: Suction port, 32: Retaining plate, 32a: Suction port, 33: Suction path, 34: Piping, 35: Suction source, 40: Lifting mechanism, 41: Guide rail, 42: Lifting plate, 43: Ball screw, 44: Motor, 45: Encoder, 50: Extension table, 50a: Suction groove, 60: Curing means, 61: Case, 61A: Side wall, 61B: Base plate, 61a: Suction port, 62: UV lamp, 63: Suction path, 64: Piping, 65: Suction source, 70: Liquid resin supply means, 71: Dispenser, 72: Resin tank, 73, 74: Resin piping, 75: Resin supply nozzle, 80: Internal pressure relief means, 81: Load sensor (load detection unit), 82: Control unit, 83, 84: Distance sensor (distance detection unit) 100: Casing, 110: Cassette compartment, 111: First cassette, 112: Second cassette 120: Base, 123: Spindle, 124: Mount, 125: Grinding wheel 125a: Base, 125b: Grinding wheel, 130: Column, 140: Lifting mechanism 150: Clamper, 200: Chuck table, 200A: Porous member, 201: Piping, 202: Suction source, CL1: Rotation axis of the chuck table, CL2: Rotation axis of the spindle, F,F1: Load, F S : Load setting value, H, H1, H2, H3: Distance between the holding table and the extension table, H S : Distance setting value, P: Protective material, R: Resin, r: Liquid resin, S: Sheet, SR: Sheet roll t: time, V1, V2, V3: on / off valve, W: wafer

Claims

1. A protective member forming apparatus for forming a protective member that protects the entire surface of one side of a wafer by curing a liquid resin spread over the entire surface of one side of the wafer, An expansion table that spreads liquid resin across the entire surface of one side of the wafer on the expansion surface, A holding table that holds a wafer by suction on a holding surface facing the expansion surface of the expansion table, A lifting mechanism for raising and lowering the holding table and the extension table relative to each other, A liquid resin supply means for supplying liquid resin between the expansion table and the wafer, An internal pressure relief means comprising a load detection unit for detecting the load acting on the holding table or the expansion table that holds the wafer when the liquid resin is being spread, or a distance detection unit for detecting the distance between the expansion table and the holding table, and a control unit for driving and controlling the lifting mechanism, for removing the internal pressure of the liquid resin spread over the entire surface of one side of the wafer so that it becomes equal to atmospheric pressure, A curing means for curing the liquid resin from which the internal pressure has been removed by the internal pressure removal means, A protective member forming apparatus comprising:

2. A method for forming a protective member, comprising curing a liquid resin spread over the entire surface of one side of a wafer using the protective member forming apparatus described in claim 1, wherein a protective member is formed to protect the entire surface of one side of the wafer, A liquid resin supply step of supplying liquid resin between the expansion table and the wafer held in the holding table, The expansion step involves using the lifting mechanism to move the expansion table and the holding table relative to each other in a direction that brings them closer together, thereby spreading the liquid resin over the entire surface of one side of the wafer. An internal pressure removal step is performed in which the internal pressure of the liquid resin spread over the entire surface of one side of the wafer in the expansion step is removed by the internal pressure removal means, A wafer separation step is performed to separate the wafer from the holding table after the internal pressure removal step, A curing step in which an external stimulus is applied to a liquid resin spread over the entire surface of one side of a wafer to cure the liquid resin, A method for forming a protective member, including the following.

3. In the aforementioned internal pressure removal process, After the liquid resin expansion step, the control unit drives and controls the lifting mechanism to move the expansion table and the holding table relative to each other in a direction away from each other until the load detected by the load detection unit reaches a preset value. The method for forming a protective member according to claim 2.

4. In the aforementioned internal pressure removal process, After the liquid resin expansion step, the control unit drives and controls the lifting mechanism to move the expansion table and the holding table relative to each other in a direction away from each other until the distance detected by the distance detection unit reaches a preset value. The method for forming a protective member according to claim 2.

Images