JP2014003155A - Wafer processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer processing method for obtaining a chip with an adhesive film by easily cutting the adhesive film along a predetermined division line between devices in any type of device.SOLUTION: A wafer processing method comprises the steps for: adhering an ultraviolet curable adhesive film 31 on a rear face 1b of a wafer 1 and further adhering an ultraviolet transmitting tape 32 on the adhesive film 31 (adhesive step); dividing the wafer 1 along predetermined division lines 11 into individual chips 15 (division step); arranging an a mask member 60 having an ultraviolet insulation part 61 which corresponds to a device 14 and an opening 62 which corresponds to the predetermined division line 11 on the rear face 1b side of the wafer 1 and irradiating the adhesive film 31 with ultraviolet light from the rear face 1b side of the wafer 1 through the mask member 60 to cure only part corresponding to the predetermined division lines 11 of the adhesive film 31 after the adhesive step and the division step (ultraviolet light irradiation step); and picking up the chip 15 with the adhesive film after the ultraviolet light irradiation step (pickup step).

Description

  The present invention divides a wafer such as a semiconductor wafer having a plurality of devices on its surface into chips that are separated into individual devices, and an ultraviolet curable adhesive film adhered to the back surface of the wafer along the chips. It is related with the processing method of the wafer for cut | disconnecting and obtaining each chip | tip as a chip | tip with an adhesive film.

  When mounting a semiconductor chip obtained by dividing a semiconductor wafer on a metal frame or substrate, a DAF (thickness of about several μm to 100 μm, for example, made of an epoxy resin attached to the back surface, which is the mounting surface of the device, is used. In some cases, bonding is performed through an adhesive film for die bonding called “Die Attach Film”.

  The chip with the adhesive film with the adhesive film attached to the back side is attached to the back side of the semiconductor wafer that has been thinned by grinding the back side, and the semiconductor wafer is divided along the grid-like division lines It is manufactured by a method such as cutting an adhesive film.

  On the other hand, in recent years, a dividing groove corresponding to the thickness of the device to be obtained is first formed on the surface side of the semiconductor wafer along the planned dividing line, and a protective member is attached to the surface on which the dividing groove is formed. A method of dividing the semiconductor wafer into chips by a method called a tip dicing method in which the back surface side of the semiconductor wafer is ground until reaching the dividing groove is also employed. When this tip dicing method is adopted, the semiconductor wafer is divided into chips by back grinding, and these chips are connected by a protective member, and the adhesive film is attached to the back surface of the semiconductor wafer in this state, Further, a dicing tape is applied to the adhesive film, and finally the adhesive film is cut to obtain a chip with the adhesive film.

  Here, in order to cut the adhesive film, a method of cutting by cutting a cutting blade used for dividing the semiconductor wafer into the dividing grooves between the chips was generally used. However, the adhesive film is irradiated by laser beam irradiation. Have been proposed (Patent Document 1) and a method of expanding a tape attached to an adhesive film to break the adhesive film (Patent Document 2).

  In addition to these, as a simpler method, an adhesive film having a property of causing a crosslinking reaction by ultraviolet irradiation is used, and the portion exposed between the chips by irradiating ultraviolet rays from the surface side of the semiconductor wafer is used. There has been proposed a method of obtaining a chip with an adhesive film by causing a cross-linking reaction to the adhesive film and leaving the cross-linking reaction portion to pick up (Patent Document 3: FIG. 3).

JP 2010-064125 A JP 2006-049591 A JP 2002-118081 A

  However, for example, as in an ultraviolet erasable ROM, depending on the type of device, irradiation of the device with ultraviolet rays may adversely affect the device function. Such devices include ultraviolet rays disclosed in Patent Document 3 above. A method of irradiating ultraviolet rays from the surface side of a semiconductor wafer using an adhesive film having a property of causing a crosslinking reaction by irradiation cannot be applied.

  The present invention has been made in view of the above circumstances, and the main problem thereof is the processing of a wafer that can easily cut the adhesive film along the chip regardless of the type of device to obtain the chip with the adhesive film. It is to provide a method.

  The wafer processing method of the present invention is a wafer processing method in which a device is formed in each of the regions partitioned by a plurality of division lines intersecting the surface, and is bonded to the back surface of the wafer by ultraviolet irradiation. A film is attached and the back surface of the wafer is covered with the adhesive film, and an adhesive step of adhering a tape that transmits ultraviolet light onto the adhesive film, and the wafer is divided into individual chips along the division line. A mask member having a splitting step for splitting, an ultraviolet shielding part corresponding to the device on the back side of the wafer and an opening corresponding to the planned split line is disposed, and the mask member is interposed from the back side of the wafer through the mask member. An ultraviolet irradiation step for irradiating the adhesive film with ultraviolet rays to cure the adhesive film corresponding to the division line, and the division step. After performing the ultraviolet irradiation step and flop, characterized in that it comprises a pickup step for picking up the chip in which the adhesive film is adhered from the tape.

  According to the present invention, after dividing the wafer into chips divided into individual devices along the division line, the ultraviolet shielding part corresponding to the device and the opening part corresponding to the division line from the back side of the wafer, The adhesive film is irradiated with ultraviolet rays through a mask member having The part of the adhesive film corresponding to the planned division line is cured by the irradiation of ultraviolet rays, dissociates from the part adhered to the back surface of the chip, and becomes breakable. For this reason, after passing through the pick-up step, the adhesive film is picked up with the part attached to the back side of the chip attached to the chip, and the part along the planned division line cured by UV irradiation is attached to the tape It remains as it is. That is, a chip with an adhesive film is picked up, and by picking up, the adhesive film is broken and cut along a chip surrounded by a line to be divided. When irradiating with ultraviolet light, the active area of the device is not irradiated with ultraviolet light, so even if the device is adversely affected by ultraviolet irradiation, the device will not be adversely affected by ultraviolet irradiation, and the adhesive film will be applied to the chip. Can be broken along.

  According to the present invention, it is possible to provide a wafer processing method that can easily cut an adhesive film along a line to be divided between chips and obtain a chip with an adhesive film regardless of the type of device. .

It is a perspective view of a wafer processed into a plurality of chips with an adhesive film by one embodiment of the present invention. It is a side view which shows the state which is performing the dicing of the tip dicing method which is an example of the division | segmentation step in one Embodiment, (b) The side view which shows the wafer division | segmentation state after wafer back surface grinding. It is a side view which shows the sticking step of one Embodiment. It is a perspective view which shows the sticking step of one Embodiment. It is a side view which shows the ultraviolet irradiation step of one Embodiment. It is a side view which shows the pick-up step of one Embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
(1) Wafer FIG. 1 shows a wafer 1 processed into a plurality of chips with an adhesive film in this embodiment. The wafer 1 is a disk-shaped semiconductor wafer having a thickness of, for example, about several hundred μm. On the surface 1 a of the wafer 1, a plurality of rectangular regions 13 are partitioned by grid-like division scheduled lines 11 set on the surface 1 a. A device 14 having an electronic circuit made of, for example, IC or LSI is formed on the surface of the rectangular region 13. Hereinafter, the processing method of this embodiment is demonstrated in order of a process.

(2) Processing Method (2-1) Dividing Step The wafer 1 is cut along the dividing line 11, divided into individual devices 14 and divided into a plurality of chips. In the dividing step, for example, the above-described dicing method can be employed.

  In the first dicing method, first, as shown in FIG. 2A, the dividing groove 21 corresponding to the thickness of the device 14 to be obtained by the cutting blade 40 is formed on the surface 1a of the wafer 1 along all the planned dividing lines 11. Form. Next, as shown in FIG. 2 (b), after attaching the protective tape 50 to the front surface 1a on which the divided grooves 21 are formed, until the rear surface 1b of the wafer 1 reaches the divided grooves 21, a grinding wheel (not shown) is used. It is a technique of grinding. As a result, the wafer 1 is divided into a plurality of chips 15 having a predetermined thickness having the devices 14 on the surface 1a.

  As the first dicing method in which the wafer 1 is divided into a plurality of chips 15 in the dividing step, a modified layer is formed in the wafer 1 by laser irradiation instead of forming the dividing grooves with the cutting blade 40 in the above method. It may be used. In that case, a pulsed laser beam having transparency with respect to the wafer 1 is irradiated along the planned dividing line 11 in a state where the condensing point is positioned inside the wafer 1, and the planned dividing line is formed inside the wafer 1. 11 is formed, and thereafter, the back surface 1b of the wafer 1 is ground to the device thickness. According to this, an external force is applied to the wafer 1 during grinding, and the wafer 1 is divided into a plurality of chips 15 along the modified layer. If the wafer 1 is not divided into a plurality of chips 15 by applying external force during grinding, the wafer 1 may be divided by applying external force again by another means after the backside grinding of the wafer 1.

(2-2) Adhesion Step Next, as shown in FIGS. 3 and 4, the adhesive film 31 is adhered to the back surface 1 b of the wafer 1, and the back surface 1 b of the wafer 1 is covered with the adhesive film 31. Further, a tape 32 that transmits ultraviolet rays is stuck on the adhesive film 31. Further, the protective tape 50 on the surface 1a side is peeled off.

  The adhesive film 31 is called a DAF (Die Attach Film) having a thickness of, for example, about several μm to 100 μm formed of a resin that is cured by ultraviolet irradiation. Affixed to the back surface 1b. As the tape 32, a tape having an adhesive layer formed on one side of a base material made of a transparent synthetic resin sheet such as stretchable polyvinyl chloride, polypropylene, polyethylene, or polyolefin is used. The tape 32 is circular and has a larger diameter than the wafer 1, and an annular frame 35 made of a metal plate having rigidity such as stainless steel is attached to the adhesive layer on the outer periphery. The wafer 1 is in a state of being concentrically attached to the adhesive layer of the tape 32 stretched inside the frame 35 via the adhesive film 31. The wafer 1 divided into a plurality of chips 15 is handled via the annular frame 35 and the tape 32.

  In addition, the order of performing the dividing step and the attaching step is arbitrary, and conversely to the above, the dividing step may be performed after the attaching step is performed first. 3 and the state shown in FIG.

(2-3) Ultraviolet Irradiation Step Next, as shown in FIG. 5, on the back surface 1 b side of the wafer 1, a mask having an ultraviolet shielding part 61 corresponding to the device 14 and an opening 62 corresponding to the division line 11. The member 60 is disposed by sticking or the like. That is, the openings 62 are formed in a lattice shape corresponding to the division lines 11, and the ultraviolet shielding part 61 is surrounded by the openings 62.

  Then, a plurality of ultraviolet irradiation lamps 70 that irradiate ultraviolet rays toward the mask member 60 are arranged on the back surface 1b side of the wafer 1, and these ultraviolet irradiation lamps 70 emit light. The ultraviolet light emitted from the ultraviolet irradiation lamp 70 passes through only the opening 62 of the mask member 60, further passes through the tape 32, and is applied to the adhesive film 31.

  Since the opening 62 is formed in a lattice shape corresponding to the division line 11, only the part corresponding to the division line 11 is cured by UV irradiation and the adhesive film 31 is adhered to the back surface of the chip 15. Dissociating from the portion, the adhesive film 31 becomes breakable along the planned dividing line 11.

(2-4) Pickup Step Next, as shown in FIG. 6, the chip 15 having the adhesive film 31 attached to the back surface is picked up from the tape 32. In this case, the surface of the device 14 is attracted and pulled up by the suction pad 81 of the pickup device 80, the adhesive film 31 is peeled off from the tape 32, and the adhesive film chip 15 with the adhesive film 31 adhered to the back surface of the device 14. Get.

(3) Operational Effects of One Embodiment According to the above-described one embodiment, in the ultraviolet irradiation step, the ultraviolet shielding part 61 corresponding to the device 14 and the opening 62 corresponding to the scheduled division line 11 from the back surface 1b side of the wafer 1. UV light is irradiated to the adhesive film 31 through the mask member 60 having the following. For this reason, the adhesive film 31 in the portion corresponding to the division line 11 is cured by the irradiation of the ultraviolet light and pasted on the back surface of the chip 15. It dissociates from the wearing part and becomes a breakable state. Thereby, after passing through the pick-up step, the adhesive film 31 is picked up while the part of the chip 15 adhered to the back surface is adhered to the chip 15, and the part along the planned dividing line 11 cured by ultraviolet irradiation is The chip 15 with the adhesive film can be easily picked up while remaining attached to the tape 32.

  In addition, when the ultraviolet ray is irradiated, the active area of the device 14 is not irradiated with the ultraviolet ray. Therefore, even when the device 14 is adversely affected by the ultraviolet ray irradiation, the device 14 is not adversely affected by the ultraviolet ray irradiation. The adhesive film 31 can be broken along the chip 15.

DESCRIPTION OF SYMBOLS 1 ... Wafer, 1a ... Wafer surface, 1b ... Back surface of wafer, 11 ... Dividing line, 13 ... Rectangular area, 14 ... Device, 15 ... Chip, 31 ... Adhesive film, 32 ... Tape, 60 ... Mask member, 61 ... UV shielding part, 62 ... Opening part.

Claims (1)

A wafer processing method in which a device is formed in each region defined by a plurality of division lines intersecting the surface,
Adhering step of adhering an adhesive film that is cured by irradiation of ultraviolet rays on the back surface of the wafer, covering the back surface of the wafer with the adhesive film, and adhering a tape that transmits ultraviolet rays on the adhesive film;
A dividing step of dividing the wafer into individual chips along the planned dividing line;
A mask member having an ultraviolet shielding part corresponding to the device and an opening corresponding to the planned dividing line is disposed on the back side of the wafer, and ultraviolet rays are applied to the adhesive film from the back side of the wafer via the mask member. An ultraviolet irradiation step of irradiating and curing the adhesive film corresponding to the division line; and
After performing the dividing step and the ultraviolet irradiation step, a pickup step of picking up the chip to which the adhesive film is attached from the tape;
A method for processing a wafer, comprising:

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