阅读说明：本技术 保护部件的形成方法 (Method for forming protective member ) 是由 斋藤良信 于 2020-10-30 设计创作，主要内容包括：本发明提供保护部件的形成方法,在使树脂成为液态而形成保护部件时,良好地识别树脂已成为液态。该保护部件的形成方法在晶片的一个面上形成保护部件,其中,该保护部件的形成方法包含如下的树脂状态识别工序：将与该晶片的一个面接触的热塑性树脂加热,并且在载台的树脂载置面与晶片保持面之间传播超声波振动,对夹持在该晶片保持面所保持的晶片的一个面与该树脂载置面之间的该热塑性树脂是否已一体化进行识别。在识别为已经一体化时,将热塑性树脂在晶片的一个面的整个面上推开,接着对热塑性树脂进行冷却而硬化。(The invention provides a method for forming a protective member, which can well identify that resin is in a liquid state when the protective member is formed by making the resin in the liquid state. The method for forming a protective member on one surface of a wafer includes a resin state recognition step of: the method includes heating a thermoplastic resin in contact with one surface of the wafer, propagating ultrasonic vibration between a resin mounting surface and a wafer holding surface of a stage, and recognizing whether or not the thermoplastic resin sandwiched between the one surface of the wafer held by the wafer holding surface and the resin mounting surface is integrated. When the integration is recognized, the thermoplastic resin is pushed out over the entire surface of one surface of the wafer, and then the thermoplastic resin is cooled and hardened.)

1. A method for forming a protective member, in which the protective member is formed on one surface of a wafer,

the method for forming the protective member includes the following steps:

a resin supply step of disposing a plurality of granular thermoplastic resins on a resin mounting surface of a stage;

a wafer holding step of holding the other surface of the wafer by the wafer holding surface of the wafer holding unit;

a contact step of moving the wafer holding unit and the stage in a direction in which they approach each other relatively by using a vertical movement mechanism, thereby bringing one surface of the wafer held by the wafer holding unit into contact with the granular thermoplastic resin;

a resin state identification step of heating the thermoplastic resin in a granular form in contact with one surface of the wafer, propagating ultrasonic vibration between the resin mounting surface and the wafer holding surface, and identifying whether or not the thermoplastic resin held between the one surface of the wafer held by the wafer holding surface and the resin mounting surface is integrated;

a pushing-off step of pushing off, by the wafer, the thermoplastic resin recognized as having been integrated in the resin state recognition step, over an entire surface of one surface of the wafer; and

a hardening step of cooling and hardening the thermoplastic resin pushed open,

the method for forming the protective member forms the protective member for protecting the entire surface of one surface of the wafer.

Technical Field

The present invention relates to a method for forming a protective member.

Background

In the technique disclosed in patent document 1, a protective member is formed on one surface of an original dicing wafer using a resin. The wafer is held by the chuck table via the protective member, and the other surface of the wafer is ground. Thus, the undulation of the wafer is removed, and the thickness of the wafer is uniformly shaped.

The formation of the protective member is performed as follows, for example. First, the sheet is arranged on a stage. A liquid resin is provided to the sheet. The liquid resin is pushed away through one face of the wafer. Thereby, the liquid resin is pushed away over the entire surface of the one surface of the wafer. Then, the liquid resin is hardened.

The liquid resin is sucked up from the container filled with the liquid resin by a pump and supplied onto the sheet on the stage. Since the liquid resin container is heavy, the replacement operation is a burden on the operator. As a countermeasure, there is a technique of using a solid granular resin.

In this technique, a granular resin is melted into a liquid state on a stage and pushed away through one surface of a wafer in a plate shape. The resin is cooled and hardened. This makes it possible to form a plate-like protective member on one surface of the wafer.

Patent document 1: japanese patent laid-open publication No. 2017-168565

In the above-described method for forming a protective member using a solid granular resin, the molten resin is held between the stage and the wafer. Therefore, it is difficult to judge whether or not the solid resin is melted. Thus, the insufficient liquid resin including the incompletely melted resin may be pushed away by the wafer. In this case, it is difficult to form a protective member having a uniform thickness, and there is a possibility that the resin in a granular form and the time taken to liquefy the resin are wasted.

Disclosure of Invention

Accordingly, an object of the present invention is to provide a method for forming a protective member, which can favorably recognize that a solid resin is in a liquid state when the protective member is formed by bringing the resin into the liquid state.

According to the present invention, there is provided a method for forming a protective member on one surface of a wafer, the method comprising: a resin supply step of disposing a plurality of granular thermoplastic resins on a resin mounting surface of a stage; a wafer holding step of holding the other surface of the wafer by the wafer holding surface of the wafer holding unit; a contact step of moving the wafer holding unit and the stage in a direction in which they approach each other relatively by using a vertical movement mechanism, thereby bringing one surface of the wafer held by the wafer holding unit into contact with the granular thermoplastic resin; a resin state identification step of heating the thermoplastic resin in a granular form in contact with one surface of the wafer, propagating ultrasonic vibration between the resin mounting surface and the wafer holding surface, and identifying whether or not the thermoplastic resin held between the one surface of the wafer held by the wafer holding surface and the resin mounting surface is integrated; a pushing-off step of pushing off, by the wafer, the thermoplastic resin recognized as having been integrated in the resin state recognition step, over an entire surface of one surface of the wafer; and a hardening step of cooling and hardening the thermoplastic resin pushed open, and the method for forming the protective member forms a protective member for protecting the entire surface of the one surface of the wafer.

In the method for forming a protective member according to the present invention, in the resin state recognition step, it is recognized whether or not the thermoplastic resin sandwiched between the one surface of the wafer and the resin placement surface is sufficiently melted and integrated. When the integration is recognized, a pushing step is performed to push the thermoplastic resin across the entire surface of the wafer. Therefore, in the present forming method, pushing away of the insufficiently melted thermoplastic resin by pressing with the wafer can be suppressed. In addition, it is possible to suppress breakage of the wafer due to the wafer pressing against the thermoplastic resin that is not sufficiently melted. This makes it possible to substantially equalize the thickness of the protective member made of thermoplastic resin formed on one surface of the wafer.

Drawings

Fig. 1 is a sectional view showing the structure of a resin protective member forming apparatus.

Fig. 2 is a sectional view showing a resin supplying process in the resin protective member forming apparatus.

Fig. 3 is a cross-sectional view showing a wafer holding process in the resin protective member forming apparatus.

Fig. 4 is a sectional view showing a wafer contact process in the resin protective member forming apparatus.

Fig. 5 is a cross-sectional view showing a heating process and a resin state recognition process in the resin protective member forming apparatus.

Fig. 6 is a graph showing an example of ultrasonic vibrations received by the ultrasonic receiver.

Fig. 7 is a cross-sectional view showing a push-open process in the resin protective member forming apparatus.

Fig. 8 is a sectional view showing cooling (hardening) in the resin protective member forming apparatus.

Fig. 9 is a sectional view showing a separation process in the resin protective member forming apparatus.

Fig. 10 is a sectional view showing a wafer carrying-out process in the resin protective member forming apparatus.

Description of the reference symbols

1: a resin protective member forming device; 2: a vacuum forming chamber; 3: a cover; 5: a cover opening and closing mechanism; 7: a vacuum pump; 10: a wafer holding unit; 12: a wafer holding table; 13: a wafer holding surface; 14: an air supply source; 15: a gas passage; 16: an attraction source; 17: an ultrasonic wave transmitting unit; 18: an ultrasonic oscillator; 20: a stage; 22: a resin mounting table; 23: a resin mounting surface; 24: a Peltier element; 24 a: an upper surface; 24 b: a lower surface; 25: 1 st power line; 26: a 2 nd power line; 27: a switch; 28: a direct current power supply; 33: an ultrasonic receiver; 34: an ultrasonic receiving unit; 30: an up-down moving mechanism; 60: a load detector; 40: a wafer carrying mechanism; 50: a resin conveying mechanism; 70: a control unit; s: melting the resin layer; w: a wafer; wb: and (2) a second surface.

Detailed Description

A resin protective member forming apparatus 1 of the present embodiment shown in fig. 1 melts a solid granular thermoplastic resin P placed on a resin placing surface 23 of a stage 20, and hardens the thermoplastic resin pushed away over the entire surface of one surface of a wafer W to form a protective member. The material of the thermoplastic resin P is, for example, polyolefin. The resin mounting surface 23 is coated with, for example, fluorine so that the mounted thermoplastic resin can be easily peeled off.

The resin protective member forming apparatus 1 includes: a wafer holding unit 10 that holds a wafer W by a wafer holding surface 13 in the vacuum forming chamber 2; a stage 20 having a resin mounting surface 23 on which a granular thermoplastic resin P is mounted; and an up-down moving mechanism (up-down moving mechanism) 30.

The vacuum forming chamber 2 is a housing of the resin-protected-component forming apparatus 1 capable of making the inside vacuum, and includes an opening 4, a cover 3 capable of covering the opening 4, a cover opening and closing mechanism 5 for opening and closing the cover 3, and a vacuum pump 7 for making the inside of the vacuum forming chamber 2 vacuum.

The wafer holding unit 10 includes: a support column 11 extending through the upper surface of the vacuum forming chamber 2; and a wafer holding table 12 provided at the lower end of the support column 11 and disposed in the vacuum forming chamber 2. The lower surface of the wafer holding table 12 serves as a wafer holding surface 13 for sucking and holding the wafer W. Further, a vacuum seal 2a for maintaining a vacuum in the vacuum forming chamber 2 is provided in a penetrating portion of the support column 11 on the upper surface of the vacuum forming chamber 2.

The support column 11 and the wafer holding table 12 are provided with a ventilation path 15 connected to an air supply source 14 and a suction source 16. The wafer holding surface 13 of the wafer holding table 12 is configured to selectively communicate with an air supply source 14 and a suction source 16 via an air passage 15. The wafer holding unit 10 can suction and hold the wafer W by the wafer holding surface 13 communicating with the suction source 16.

The wafer holding table 12 of the wafer holding unit 10 has an ultrasonic oscillator 18 in the vicinity of the wafer holding surface 13. The ultrasonic oscillator 18 is connected to an ultrasonic transmission unit 17 having a high-frequency power supply, for example. The ultrasonic oscillator 18 oscillates an ultrasonic wave using the high-frequency power from the ultrasonic transmission unit 17.

The stage 20 includes: a support column 21 extending through the bottom surface of the vacuum forming chamber 2; and a resin mounting table 22 provided at the upper end of the support column 21 and disposed in the vacuum forming chamber 2. The upper surface of the resin mounting table 22 is a resin mounting surface 23 on which the thermoplastic resin P is mounted.

The resin mounting surface 23 is disposed to face the wafer holding surface 13 of the wafer holding unit 10. Further, a vacuum seal 2b for maintaining a vacuum in the vacuum forming chamber 2 is provided in a penetrating portion of the support column 21 on the bottom surface of the vacuum forming chamber 2.

Further, the resin mounting table 22 of the stage 20 has an ultrasonic receiver 33 in the vicinity of the resin mounting surface 23. The ultrasonic receiver 33 receives the ultrasonic vibration propagated to itself, converts the ultrasonic vibration into a voltage, and transmits the voltage to the ultrasonic receiving unit 34.

The resin protective member forming apparatus 1 includes a wafer carrying mechanism 40 and a resin carrying mechanism 50. The wafer transfer mechanism 40 and the resin transfer mechanism 50 are transfer members such as robot arms. The wafer transfer mechanism 40 and the resin transfer mechanism 50 may be different members or may be a common member.

The wafer transfer mechanism 40 transfers the wafer W from the outside to the vacuum forming chamber 2. The wafer transfer mechanism 40 can dispose the wafer W at a position facing the wafer holding surface 13 of the wafer holding unit 10 in the vacuum forming chamber 2 through the opening 4. In the wafer holding unit 10, the wafer W thus arranged can be held by suction by the wafer holding surface 13 communicating with the suction source 16.

The resin conveying mechanism 50 conveys the plurality of granular thermoplastic resins P from the outside to the resin protective member forming apparatus 1. The resin transfer mechanism 50 places the granular thermoplastic resin P on the resin placement surface 23 of the stage 20 in the vacuum forming chamber 2 through the opening 4 of the vacuum forming chamber 2. Further, an annular convex portion may be formed on the outer periphery of the resin mounting surface 23 so that the granular thermoplastic resin P does not fall off from the resin mounting surface 23.

The vertical movement mechanism 30 is disposed on the upper surface of the vacuum forming chamber 2 and is connected to the support column 11 of the wafer holding unit 10. The vertical movement mechanism 30 moves the wafer holding unit 10 and the stage 20 relatively along the Z-axis direction, which is a vertical direction perpendicular to the resin mounting surface 23. In the present embodiment, the vertical movement mechanism 30 moves the support column 11 of the wafer holding unit 10 in the Z-axis direction. That is, the vertical movement mechanism 30 is configured to move the wafer holding unit 10 in the Z-axis direction with respect to the fixed stage 20.

Specifically, the vertical movement mechanism 30 includes: an arm 31 connected to the support column 11 and extending in the horizontal direction; a drive lever 32 coupled to the arm 31 and extending in the Z-axis direction; and a sensor 35 that detects the moving distance. The drive lever 32 is moved up and down by a drive source (not shown), and the arm 31 and the wafer holding unit 10 (support column 11) coupled to the arm 31 are moved up and down in the Z-axis direction. The moving distance of the wafer holding unit 10 is detected by the sensor 35.

Further, the resin protective member forming apparatus 1 has a load detector 60. The load detector 60 is connected to the support column 11 of the wafer holding unit 10 via the vertical movement mechanism 30. The load detector 60 detects a load applied to the wafer holding unit 10 (i.e., a force with which the wafer W presses the thermoplastic resin P) when the wafer holding unit 10 and the stage 20 are brought into contact with each other via the wafer W and the thermoplastic resin P.

The stage 20 of the present embodiment includes a peltier element 24 therein. The peltier element 24 is an example of a temperature control device disposed on the stage 20. The peltier element 24 has, for example, a flat plate shape, and is disposed in parallel with the resin mounting surface 23 in the vicinity of the resin mounting surface 23 in the resin mounting table 22 of the stage 20. The peltier element 24 is parallel to the resin mounting surface 23 and has an upper surface 24a close to the resin mounting surface 23 and a lower surface 24b far from the resin mounting surface 23.

Further, one ends of the 1 st power line 25 and the 2 nd power line 26 that surround the support column 21 and the resin mounting table 22 are attached to both ends of the peltier element 24. The other ends of the 1 st power line 25 and the 2 nd power line 26 are connected to a dc power supply 28 via a switch 27.

The dc power supply 28 is a power supply for supplying dc current to the peltier element 24. The switch 27 has a function of connecting the dc power supply 28 to the peltier element 24 via the 1 st power line 25 and the 2 nd power line 26, and a function of switching the direction of the dc current flowing from the dc power supply 28 to the peltier element 24 via the 1 st power line 25 and the 2 nd power line 26.

That is, the switch 27 is configured to switch the direction of the direct current supplied to the peltier element 24 between a 1 st direction in which the upper surface 24a of the peltier element 24 is heated and a 2 nd direction in which the upper surface 24a of the peltier element 24 is cooled, the 2 nd direction being a direction opposite to the 1 st direction. In addition, the lower surface 24b of the peltier element 24 is cooled when the direct current flows in the 1 st direction and heated when the direct current flows in the 2 nd direction.

The resin-protected-component forming apparatus 1 further includes a control unit 70 that controls each component of the resin-protected-component forming apparatus 1, and the control unit 70 includes a computer. The control unit 70 controls each component of the resin protective member forming apparatus 1 to form a protective member on the entire surface of one surface of the wafer W.

Next, a description will be given of an operation of forming the protective member on the wafer W in the resin protective member forming apparatus 1.

First, the control unit 70 controls the cover opening/closing mechanism 5 to open the cover 3 of the vacuum forming chamber 2 and expose the opening 4. Then, the control unit 70 moves the resin conveying mechanism 50 holding the plurality of granular thermoplastic resins P in the-X direction, thereby conveying the thermoplastic resins P into the vacuum forming chamber 2 from the exposed opening 4. Further, the control unit 70 controls the resin conveying mechanism 50 so that a plurality of thermoplastic resins P are arranged (mounted) on the resin mounting surface 23 of the stage 20 at substantially uniform intervals in a planar manner, for example, as shown in fig. 2 (resin supply step).

Next, the control unit 70 causes the suction source 16 shown in fig. 1 to communicate with the wafer holding surface 13 of the wafer holding unit 10. Thereby, the wafer holding surface 13 becomes a negative pressure. The control unit 70 moves the wafer transfer mechanism 40 holding the wafer W in the-X direction, so that the wafer W is carried into the vacuum forming chamber 2 through the exposed opening 4 and is disposed at a position facing the wafer holding surface 13. As shown in fig. 3, the control unit 70 suctions and holds the 1 st surface (the other surface) Wa of the wafer W by the wafer holding surface 13. Thus, the wafer W is disposed above the thermoplastic resin P placed on the resin placement surface 23 with the 2 nd surface (one surface) Wb facing the thermoplastic resin P (wafer holding step).

Next, the control unit 70 controls the cover opening/closing mechanism 5 shown in fig. 1 to close the cover 3 of the vacuum forming chamber 2 and seal the opening 4.

The control unit 70 controls the vertical movement mechanism 30 to move the wafer holding unit 10 downward along the Z-axis direction. As a result, as shown in fig. 4, the 2 nd surface Wb of the wafer W held by the wafer holding surface 13 of the wafer holding unit 10 is brought into contact with the plurality of thermoplastic resins P held by the resin mounting surface 23 of the stage 20 (wafer contact step).

In this way, the control unit 70 relatively moves the wafer holding unit 10 and the stage 20 in the approaching direction by using the vertical movement mechanism 30, and brings the 2 nd surface Wb of the wafer W held by the wafer holding unit 10 into contact with (presses with a relatively weak force) the granular thermoplastic resin P held by the resin placement surface 23. In this state, the control unit 70 controls the vacuum pump 7 to vacuum the inside of the vacuum forming chamber 2.

In this state, when the atmospheric pressure in the vacuum forming chamber 2 becomes equal to or lower than a predetermined value, the control unit 70 controls the switch 27 shown in fig. 1 to connect the dc power supply 28 to the peltier element 24 via the 1 st power line 25 and the 2 nd power line 26. The control unit 70 controls the switch 27 to set the direction of the dc current from the dc power supply 28 to the 1 st direction in which the upper surface 24a of the peltier element 24 is heated (indicated by "h" in the figure) as indicated by an arrow D1 in fig. 5.

In this way, the control unit 70 heats the upper surface 24a of the peltier element 24 by flowing a direct current in the 1 st direction while pressing the thermoplastic resin P against the 2 nd surface Wb of the wafer W, and heats the resin mounting surface 23 and the thermoplastic resin P on the resin mounting surface 23 to melt the thermoplastic resin P (heating step). At this time, the lower surface 24b of the peltier element 24 is cooled (indicated by "c" in the drawing).

The control unit 70 controls the ultrasonic wave transmitting unit 17 to oscillate the ultrasonic wave from the ultrasonic oscillator 18. The ultrasonic wave oscillated from the ultrasonic oscillator 18 propagates between the wafer holding surface 13 and the resin placement surface 23 (i.e., through the thermoplastic resin P). Then, the control unit 70 acquires a voltage corresponding to the amplitude of the ultrasonic vibration received by the ultrasonic receiver 33 via the ultrasonic receiving unit 34. The control unit 70 obtains the amplitude amount of the ultrasonic vibration received by the ultrasonic receiver 33 from the acquired voltage. The control unit 70 determines whether or not the thermoplastic resin P sandwiched between the wafer holding surface 13 and the resin placement surface 23 is in a liquid state and integrated (sufficiently melted) based on the obtained amplitude amount of the ultrasonic vibration (resin state identification step).

Fig. 6 shows a graph of the ultrasonic vibrations received by the ultrasonic receiver 33. In the graph, the vertical axis represents the amplitude (a) and the horizontal axis represents the time (T). When the thermoplastic resin P is not sufficiently liquefied and is not integrated, the ultrasonic vibration received by the ultrasonic receiver 33 has a relatively small amplitude as indicated by a broken line R0 in fig. 6. On the other hand, when the thermoplastic resin P is sufficiently liquefied and integrated, the ultrasonic vibrations received by the ultrasonic receiver 33 have a relatively large amplitude as indicated by a solid line R1 in fig. 6.

Therefore, for example, when the amplitude of the ultrasonic vibration received by the ultrasonic receiver 33 is equal to or greater than a predetermined value, the control unit 70 determines that the thermoplastic resin P sandwiched between the wafer holding surface 13 and the resin placement surface 23 is melted and integrated (liquefied).

When determining that the thermoplastic resin P sandwiched between the wafer holding surface 13 and the resin mounting surface 23 is melted and integrated, the control unit 70 controls the vertical movement mechanism 30 to press the integrated thermoplastic resin P more strongly against the 2 nd surface Wb of the wafer W. In this way, the control unit 70 pushes away the thermoplastic resin P integrated between the resin mounting surface 23 and the 2 nd surface Wb of the wafer W over the entire 2 nd surface Wb by the wafer W. As a result, as shown in fig. 7, the molten resin layer S formed of the thermoplastic resin P melted and pushed open is formed so as to cover the entire surface of the 2 nd surface Wb of the wafer W (pushing open step).

Then, the control unit 70 controls the switch 27 (see fig. 1) so that the dc current from the dc power supply 28 flows in the 2 nd direction, which is the direction opposite to the 1 st direction and which cools the upper surface 24a of the peltier element 24, as indicated by an arrow D2 in fig. 8. Thus, the control unit 70 cools the upper surface 24a of the peltier element 24 while pressing the molten resin layer S with the 2 nd surface Wb of the wafer W. By thus cooling the upper surface 24a, the control unit 70 cools the resin mounting surface 23 and the molten resin layer S on the resin mounting surface 23, and hardens the molten resin layer S. Thereby, the protective member Sa (see fig. 9) formed of the cured molten resin layer S is formed on the entire 2 nd surface Wb of the wafer W (cooling (curing) step). In addition, at this time, the lower surface 24b of the peltier element 24 is heated.

Subsequently, the control unit 70 controls the switch 27 to disconnect the direct current power supply 28 from the peltier element 24. The control unit 70 controls the vertical movement mechanism 30 shown in fig. 1 to move the wafer holding unit 10 upward in the Z-axis direction, and separates it from the stage 20 (resin mounting surface 23) as shown in fig. 9. That is, the control unit 70 separates the protective member Sa formed on the 2 nd surface Wb of the wafer W from the resin placement surface 23. Thus, the control unit 70 can hold the wafer W having the protective member Sa formed on the 2 nd surface Wb by the wafer holding surface 13 of the wafer holding unit 10 (separation step).

Next, the control unit 70 stops the vacuum pump 7 shown in fig. 1, and controls the cover opening/closing mechanism 5 to open the cover 3 of the vacuum forming chamber 2 and expose the opening 4. Thereby, the vacuum in the vacuum forming chamber 2 is broken.

As shown in fig. 10, the control unit 70 causes the wafer transfer mechanism 40 to be disposed opposite the wafer holding surface 13 of the wafer holding unit 10 and to come into contact with the protective member Sa covering the 2 nd surface Wb of the wafer W. In addition, the control unit 70 communicates the wafer holding face 13 of the wafer holding unit 10 with the air supply source 14. Thus, the wafer holding surface 13 is released from the suction of the wafer W, and the wafer W is held by the wafer transfer mechanism 40.

Then, the control unit 70 moves the wafer W in the + X direction as indicated by an arrow E by the wafer transfer mechanism 40, and carries the wafer W out of the vacuum forming chamber 2 through the opening 4 (wafer carrying-out step). The wafer transfer mechanism 40 may hold the 1 st surface Wa of the wafer W.

As described above, in the present embodiment, in the resin state recognition step, the ultrasonic vibration is propagated between the resin mounting surface 23 and the wafer holding surface 13, and it is recognized whether or not the thermoplastic resin P sandwiched between the 2 nd surface Wb of the wafer W held by the wafer holding surface 13 and the resin mounting surface 23 is sufficiently melted and integrated. When the integration is recognized, a pushing step is performed to push the thermoplastic resin P off the entire 2 nd surface Wb of the wafer W. Therefore, in the present embodiment, the thermoplastic resin P that is not sufficiently melted can be prevented from being pushed and pushed away by the wafer W. Further, it is possible to suppress the wafer W from being damaged by the wafer W pressing the thermoplastic resin P that is not sufficiently melted. This makes it possible to substantially equalize the thickness of the protective member Sa formed of the thermoplastic resin P on the 2 nd surface Wb of the wafer W.

In the present embodiment, in the heating step, the upper surface 24a of the peltier element 24 is heated, and the resin mounting surface 23 and the thermoplastic resin P mounted thereon are heated to obtain the molten resin layer S. At this time, the lower surface 24b of the peltier element 24 is cooled, and the cooling effect of cooling the resin placement surface 23 can be enhanced in the cooling (hardening) step which is the next step. Therefore, the time (the time of the cooling (curing) step) for forming the protective member Sa on the 2 nd surface Wb of the wafer W by cooling and curing the molten resin layer S can be shortened.

In the present embodiment, in the heating step and the cooling step, a direct current is passed through the peltier element 24 to heat or cool the upper surface 24a of the peltier element 24, thereby heating the granular thermoplastic resin P or cooling the molten resin layer S. However, the structure for implementing such heating and cooling is not limited to the peltier element 24. Instead of the peltier element 24, another temperature control device disposed on the stage 20 or the wafer holding unit 10 may be used.

In the present embodiment, the load detector 60 provided on the upper surface of the vacuum forming chamber 2 detects the load applied to the wafer holding unit 10 when the wafer holding unit 10 and the stage 20 are brought into contact with each other through the wafer W and the molten resin layer S. Such a load detector may be provided in the wafer holding table 12 of the wafer holding unit 10 or in the resin stage 22 of the stage 20.