JP2011243907A - Method of processing wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of processing a wafer in which a reinforcement plate is easily peeled from a top surface of the wafer.SOLUTION: The method of processing the wafer having, on a top surface, a device region in which a plurality of devices are formed and an outer peripheral excessive region surrounding the device region includes a reinforcement plate formation process of applying the heat resistant bond agent to the top surface of the wafer, sticking a reinforcement ring corresponding to the outer peripheral excessive region on the outer peripheral excessive region, and solidifying the heat resistant bond agent to form the reinforcement plate of the heat resistant bond agent and reinforcement ring; a reverse-surface grinding process of holding the reinforcement plate by a chuck table, and grinding the reverse surface of the wafer by a grindstone; a through electrode formation process of forming a through electrode connected to electrodes of the devices formed on the surface of the wafer from the reverse surface of the wafer arranged on the reinforcement plate; and a reinforcement plate removal process of supplying a solvent for fusing the heat resistant bond agent to the reinforcement plate to fuse the reinforcement plate, and removing the reinforcement ring.

Description

  The present invention relates to a wafer processing method in which a back electrode of a wafer is ground and then a through electrode connected to an electrode of a device formed on the front surface of the wafer from the back surface of the wafer is formed.

  A semiconductor wafer formed on the surface by dividing a plurality of devices such as IC, LSI, etc. by grid-like division lines is divided into individual devices by a dicing apparatus, and the divided devices are various types such as mobile phones and personal computers. Widely used in electrical equipment.

  In recent semiconductor device technology, a stacked semiconductor package in which a plurality of semiconductor chips are stacked is effectively used to achieve high density, miniaturization, and thinning. In this semiconductor device technology, the back surface of the wafer is ground with a grinding wheel to reduce the thickness of the wafer to about 50 μm, and then a through electrode is formed from the back surface of the wafer to the device electrode formed on the surface. Before reinforcing the back surface of the wafer, a reinforcing plate is attached to the surface of the wafer via a bonding agent.

  However, since the wafer is exposed to a relatively high temperature environment when forming a through electrode connected to the electrode of the device, it has a strength capable of withstanding a high temperature of 250 ° C. as a bonding agent for attaching a reinforcing plate to the surface of the wafer. The epoxy-type bond agent which has is used.

  Since the bond agent has such a strength that it can withstand a high temperature of 250 ° C., conventionally, to remove the reinforcement plate from the surface of the wafer, the reinforcement plate is heated to raise the bond agent to a temperature of 250 ° C. or higher. The reinforcing plate is detached while being slid from the surface of the wafer so as not to put a burden on the wafer.

JP 2003-249620 A JP 2004-95849 A JP 2004-119593 A

  As described above, in the conventional wafer processing method, a heat-resistant bond agent having a strength capable of withstanding a high temperature of 250 ° C. is used as a bond agent for adhering the reinforcing plate to the wafer, so that a through electrode is formed on the wafer. After that, there is a problem that it is difficult to peel the reinforcing plate from the surface of the wafer.

  The present invention has been made in view of these points, and an object of the present invention is to provide a wafer processing method in which a reinforcing plate can be easily peeled off from the surface of the wafer.

  According to the present invention, there is provided a wafer processing method having a device region having a plurality of devices formed on the surface and an outer peripheral surplus region surrounding the device region, wherein a heat-resistant bond agent is applied to the surface of the wafer and the outer periphery is applied. A reinforcing plate forming step of sticking a reinforcing ring corresponding to the surplus region to the outer peripheral surplus region to solidify the heat resistant bond agent, and forming a reinforcing plate with the heat resistant bond agent and the reinforcing ring; A back surface grinding process in which the back surface of the wafer is ground with a grinding wheel while holding the reinforcing plate on the chuck table, and a through electrode connected to the device electrode formed on the front surface of the wafer from the back surface of the wafer disposed on the reinforcing plate A through electrode forming step for forming the reinforcing plate, and a solvent for melting the heat-resistant bond agent is supplied to the reinforcing plate to melt the reinforcing plate and The wafer processing method of the reinforcing plate removing step of removing the strong ring, characterized by comprising a are provided.

  Preferably, in the wafer processing method, after the reinforcing plate removing step is performed, the back surface of the wafer is attached to a dicing tape having an outer peripheral portion attached to the annular frame, and the wafer is attached to the annular frame via the dicing tape. It further includes a wafer supporting step for supporting, and a wafer dividing step for dividing the wafer supported by the annular frame into individual devices.

  According to the present invention, the reinforcing plate to be adhered to the surface of the wafer is formed of the heat-resistant bond agent and the reinforcing ring, so that the strength can be sufficiently maintained by the reinforcing ring, and the through electrode can be formed without impairing handling properties. The process can be carried out.

  When removing the reinforcing plate, it is possible to easily remove the heat-resistant bond agent together with the reinforcing ring by simply supplying a solvent for melting the heat-resistant bond agent to the reinforcing plate, and productivity is improved.

It is a figure which shows a heat resistant bond agent supply process. FIG. 2A is a perspective view showing a state in which the reinforcing ring is attached to the surface of the wafer, and FIG. It is a back surface side perspective view. It is a longitudinal cross-sectional view of the chuck table suitable for implementing a back surface grinding process. It is a perspective view of the back surface grinding process of a wafer. It is explanatory drawing of a penetration electrode formation process. It is a perspective view of a reinforcement plate removal process. It is a perspective view which shows a wafer support process. It is a perspective view which shows a wafer division | segmentation process.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, a perspective view of a heat-resistant bond agent supplying process is shown. In the present embodiment, the heat-resistant bond agent 10 is supplied to the surface 2a of the wafer 2 by spin coating. First, a semiconductor wafer (hereinafter abbreviated as “wafer”) 2 is sucked and held on a rotatable chuck table 4.

  A plurality of streets (division lines) 3 are formed in a lattice pattern on the surface 2 a of the wafer 2, and devices 5 such as ICs and LSIs are formed in each region partitioned by the plurality of streets 3. . The wafer 2 has a device region 6 in which a plurality of devices 5 are formed on the surface 2 a and an outer peripheral surplus region 7 that surrounds the device region 6.

  In order to spin coat the heat-resistant bond agent on the surface 2a of the wafer 2, the heat-resistant bond agent 10 is applied to the wafer 2 from the heat-resistant bond agent dropping portion 8 while rotating the chuck table 4 in the arrow A direction at, for example, about 300 rpm. It is dripped on the surface 2a.

  When the chuck table 4 is rotated for at least 5 seconds or more, the dropped heat-resistant bond agent 10 is uniformly spin-coated on the surface 2a of the wafer 2, and the heat-resistant bond agent layer 11 is formed. The heat resistant bond agent 10 is formed of an epoxy resin and has a strength capable of withstanding a high temperature of 250 ° C.

  After the heat-resistant bond agent layer 11 is formed on the surface 2a of the wafer 2, as shown in FIG. 2A, the reinforcing ring 12 corresponding to the outer peripheral surplus region 7 is attached to the wafer 2 through the heat-resistant bond agent layer 11. The reinforcing plate 13 composed of the heat-resistant bond agent layer 11 and the reinforcing ring 12 is formed on the surface 2a of the wafer 2 by sticking to the surface and baking at a predetermined temperature for a predetermined time.

  Thus, after forming the reinforcing plate 13 composed of the heat-resistant bond agent layer 11 and the reinforcing ring 12 on the front surface 2a of the wafer 2, a back surface grinding step of holding the reinforcing plate 13 and grinding the back surface 2b of the wafer 2 is performed. carry out.

  In the back surface supplying step, it is preferable to use a chuck table 14 as shown in FIG. The chuck table 14 has a small diameter portion 14a having a diameter slightly smaller than the inner diameter of the reinforcing ring 12, and a suction holding portion 15 made of porous ceramic or the like is disposed in the small diameter portion 14a. The suction holding unit 15 is connected to a negative pressure suction source (not shown) via a suction path 17.

  Using the chuck table 14 configured as described above and the grinding unit 16 as shown in FIG. 4, the back grinding process of the wafer 2 is performed. In FIG. 4, the grinding unit 16 of the grinding apparatus is fastened with a spindle 18 that is rotationally driven by a motor (not shown), a wheel mount 20 that is fixed to the tip of the spindle 18, and a plurality of screws 27 that are detachably attached to the wheel mount 20. And a grinding wheel 26 to be operated.

  For example, as shown in FIG. 4, the grinding wheel 26 has a plurality of grinding wheels 24 in which diamond abrasive grains having a particle diameter of 0.3 to 1.0 μm are hardened with vitrified bonds or the like at the free end of the annular base 22. Configured.

  In the back surface grinding process of the wafer 2, the reinforcing plate 13 is sucked and held by the chuck table 14 of the grinding device, and the back surface 2b of the wafer 2 is exposed as shown in FIG. While rotating the chuck table 14 in the direction of arrow a at 300 rpm, for example, the grinding wheel 26 is rotated in the same direction as the chuck table 14, that is, in the direction of arrow b at 6000 rpm, for example, and a grinding unit feed mechanism (not shown) is operated to perform grinding. The grindstone 24 is brought into contact with the back surface 2 b of the wafer 2.

  Then, the grinding wheel 26 is ground and fed downward by a predetermined amount at a predetermined grinding feed rate (for example, 3 to 5 μm / second), and the wafer 2 is ground. While measuring the thickness of the wafer 2 with a contact-type thickness measurement gauge (not shown), the wafer 2 is finished to a desired thickness, for example, 50 μm. The wafer 2 is ground while supplying grinding water.

  After performing the grinding process, as shown in FIG. 5, the through electrode for forming the through electrode 28 connected to the electrode of the device 5 formed on the front surface 2 a of the wafer 2 from the back surface 2 b of the wafer 2 adhered to the reinforcing plate 13. A forming step is performed.

  In this through electrode forming step, first, a plurality of through holes are formed in the wafer 2 by, for example, laser beam irradiation. As the laser beam, a laser beam having a wavelength (for example, 355 nm) having an absorptivity with respect to the wafer 2 is used, and preferably a third harmonic of a YAG laser or a YVO4 laser is used.

  Next, an insulator such as a polymer material is filled in the through hole. As a filling method, a liquid phase method is preferably used. Since the liquid phase method does not need to heat the wafer 2 to a high temperature, it can be used even for a wafer in which the device 5 is formed in advance.

  Next, a through hole is further formed in the insulator filled in the through hole by etching using a laser processing method or a lithography process. Furthermore, a conductive material such as copper, nickel, palladium, gold, or silver is embedded in the through hole.

  As the conductive material embedding method, dry plating, wet plating, jet painting method, conductive paste or molten metal film forming method, or the like can be used. The through electrode 28 is formed so as to penetrate both the front and back surfaces of the wafer 2, and is electrically connected to the electrode of the device 5 formed on the surface 2 a of the wafer 2.

  After the through electrode forming step is performed, as shown in FIG. 6, the wafer 2 is sucked and held by the chuck table 30, and the solvent 34 such as methyl ethyl ketone is removed from the solvent supply device 32 while the chuck table 30 is rotated in the arrow A direction. It is supplied onto a reinforcing plate 13 composed of the agent layer 11 and the reinforcing ring 12. Thereby, the heat-resistant bond agent layer 11 is melted, and the reinforcing ring 12 adhered to the wafer 2 by the heat-resistant bond agent is also removed.

  After the reinforcing plate 13 is removed from the surface of the wafer 2 in this way, the back surface of the wafer 2 is adhered on the dicing tape 52 whose outer peripheral portion is adhered to the annular frame 54 as shown in FIG. A wafer support process for supporting 2 on the annular frame 54 through the dicing tape 52 is performed.

  Next, as shown in FIG. 8, the wafer 2 is sucked and held by the chuck table 50 of the cutting device via the dicing tape 52, and the wafer 2 is fully cut along the scheduled division line 3 by the cutting blade 36 of the cutting unit 32. A cutting groove 56 is formed, and a wafer dividing step for dividing the wafer 2 into the individual devices 5 is performed.

  When cutting of all the streets 3 extending in the first direction is completed while indexing the cutting blade 36 by street pitch, the chuck table 50 is rotated 90 degrees, and then the second direction orthogonal to the first direction is set. All the streets 3 extending in the direction are cut to divide the wafer 2 into individual devices D.

2 Semiconductor wafer 5 Device 10 Heat-resistant bond agent 11 Heat-resistant bond agent layer 12 Reinforcement ring 13 Reinforcement plate 28 Through electrode 34 Solvent 52 Dicing tape 54 Annular frame

Claims (2)

A wafer processing method having a device region in which a plurality of devices are formed on a surface and an outer peripheral surplus region surrounding the device region,
Applying a heat-resistant bond agent to the surface of the wafer and sticking a reinforcing ring corresponding to the outer peripheral surplus region to the outer peripheral surplus region to solidify the heat resistant bond agent, the heat-resistant bond agent and the reinforcing ring A reinforcing plate forming step of forming the reinforcing plate with,
A back grinding process in which the reinforcing plate is held by a chuck table and the back surface of the wafer is ground with a grinding wheel;
A through electrode forming step of forming a through electrode connected to an electrode of a device formed on the front surface of the wafer from the back surface of the wafer disposed on the reinforcing plate;
A reinforcing plate removing step of melting the reinforcing plate by supplying a solvent for melting the heat-resistant bond agent to the reinforcing plate and removing the reinforcing ring;
A wafer processing method characterized by comprising: After performing the reinforcing plate removing step, a wafer supporting step of sticking the back surface of the wafer to a dicing tape having an outer peripheral portion attached to the annular frame, and supporting the wafer with the annular frame via the dicing tape;
A wafer dividing step of dividing the wafer supported by the annular frame into individual devices;
The wafer processing method according to claim 1, further comprising:

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