JP5641766B2 - Wafer dividing method - Google Patents

Description

  The present invention relates to a method of dividing a device by irradiating a wafer with laser light.

  In recent years, processing methods for dividing a wafer into individual devices using pulsed laser light have been attempted. In this dividing method using laser light, for example, when the workpiece is a silicon wafer, the condensing point is aligned from one surface of the workpiece to the inside, and the silicon wafer is transparent, for example, the wavelength is 1064 nm. In this way, a deteriorated layer is continuously formed in the wafer along the planned dividing line. Then, by applying an external force along the planned division line whose strength has decreased due to the formation of the deteriorated layer, the workpiece can be divided along the planned division line (see, for example, Patent Document 1). . During actual processing, a protective tape is attached to the front side of the wafer device, the protective tape is held on the chuck table of the laser processing device, and pulsed laser light is emitted from the exposed back side of the wafer. doing.

Japanese Patent No. 3408805

  However, for example, when the device on the front side of the wafer is a very fragile device such as a micromachine device such as an acceleration sensor, if the protective tape is applied to the front side, the device is damaged at the time of peeling. There is a problem of end.

  The present invention has been made in view of the above-described facts, and an object thereof is to provide a wafer dividing method that does not damage the device surface on the front surface side of the wafer.

The present invention divides a wafer in which a device region in which a plurality of micromachine devices are partitioned by a predetermined division line and an outer peripheral surplus region surrounding the device region are formed on the surface into individual micromachine devices along the predetermined division line. The present invention relates to a method for dividing a wafer. A support member preparing step for forming a recess having a size corresponding to a device region of a wafer on the surface of a support member having the same diameter as the wafer or an outer diameter larger than the wafer, and a support member preparing step After that, place the wafer on the surface of the support member with the device portion of the wafer facing the recess, apply adhesive to the outer peripheral surplus area and the outer peripheral portion of the support member, and the outer peripheral surplus of the wafer on the outer peripheral portion of the support member A bonding step to bond the area and after the bonding step to the wafer A deteriorated layer forming step and a deteriorated layer forming step were performed in which a laser beam having transparency was irradiated from the back surface side of the wafer along the planned dividing line, and an altered layer was formed along the planned dividing line inside the wafer. An expand tape adhering step for adhering an expanded tape adhering to an annular frame on the back surface of the wafer, a support member removing step for removing the support member from the wafer surface after the expand tape adhering step, and a support member After the removing step, a tape expanding step of expanding the expanded tape to break the wafer along a predetermined dividing line is included.

  In this wafer dividing method, in the deteriorated layer forming step, a deteriorated layer is formed along the planned dividing line inside the wafer, and the wafer is permeable along the boundary between the device region and the peripheral surplus region. Laser beam is irradiated from the back side of the wafer to form an altered layer inside the wafer along the boundary, and in the support member removal step, the wafer is broken along the altered layer formed along the boundary. You may make it remove the outer periphery excess area | region of the wafer fixed to the support member with the support member from the expanded tape.

  In the present invention, a recess having a size corresponding to the device region of the wafer is formed on the support member, the device region of the wafer is opposed to the recess, and the outer peripheral region of the wafer and the outer periphery of the support member are bonded, After holding the wafer without contacting the device area to the support member and dividing the wafer into devices in that state, the support member is peeled off from the wafer, so that the device is damaged when peeling the wafer from the support member. Can be prevented.

It is the flowchart which showed this invention for every step. It is a perspective view which shows an example of a wafer. It is sectional drawing which shows the support member in which the recessed part was formed. It is sectional drawing which shows schematically the state which the device area | region of the wafer and the recessed part of the support member faced. It is sectional drawing which shows schematically the state to which the wafer and the support member were adhere | attached. It is sectional drawing which shows schematically the state which forms a deteriorated layer in the inside of a wafer. It is sectional drawing which shows schematically the state which affixed the wafer on the expanded tape. It is sectional drawing which shows schematically the state which irradiates an ultraviolet-ray to an adhesive agent. It is sectional drawing which shows schematically the state which removes a support member from a wafer. It is sectional drawing which shows schematically the state with which the wafer was hold | maintained at the holding table of the tape expansion apparatus. It is sectional drawing which shows schematically the state which expanded the expanded tape in the tape expansion apparatus. It is sectional drawing which shows schematically the state which forms a deteriorated layer along the boundary part of a wafer. It is sectional drawing which shows schematically the state which removes the outer periphery excess area | region of the wafer fixed to the support member with the support member from the expanded tape.

  In the following, a case where the wafer W shown in FIG. 2 is divided will be described along the flowchart shown in FIG. 1 while referring to other drawings as appropriate.

  A wafer W shown in FIG. 2 includes a device region Wa in which a plurality of devices D are formed, and an outer peripheral surplus region Wb that surrounds the device region Wa and in which no device is formed. The device area Wa and the outer peripheral surplus area Wb are partitioned by a boundary portion Wab. The device D is formed by being partitioned by the planned division line L, and is formed on the surface W1 side. The device D includes a device having a low mechanical strength such as a micromachine device.

[1] First Embodiment (1) Support Member Preparation Step (Step S1)
As shown in FIG. 3, a support member 1 having a recess 10a formed on the surface is prepared. The support member 1 is, for example, a silicon wafer or glass having a thickness of about 700 μm, and has the same diameter as the wafer W or a larger diameter than the wafer W. The recess 10a can be formed, for example, by grinding the surface of the flat support member 1 with a grinding wheel. The recess 10a is formed to have a size corresponding to the device region Wa of the wafer W, and has the same diameter as the device region Wa or slightly larger than the device region Wa. Moreover, the recessed part 10a is formed so that it may have a depth of 40-50 micrometers, for example. The outer peripheral side of the recessed part 10a comprises the outer peripheral part 10b formed thicker in a ring shape than the recessed part 10a.

(2) Fixing step (step S2)
After the support member preparation step, as shown in FIG. 4, the device region Wa protruding on the front surface side of the wafer W and the concave portion 10 a of the support member 1 face each other. And as shown in FIG. 5, the adhesive agent 2 is apply | coated to the outer peripheral surplus area | region Wb of the wafer W and the surface of the outer peripheral part 10b of the support member 1, and the outer peripheral surplus area | region Wb of the wafer W is applied to the outer peripheral part 10b of the support member 1. Stick. As the adhesive 2, an ultraviolet curable resin is used. By bonding the wafer W and the support member 1 in this manner, the device region Wa of the wafer W is accommodated in the recess 10 a and is not in contact with the support member 1. That is, the value obtained by adding the depth of the recess 10 a and the thickness of the adhesive 2 is larger than the height of the protruding portion of the device region Wa of the wafer W.

(3) Altered layer formation step (step S3)
After the fixing step, as shown in FIG. 6, a laser beam 3a having transparency to the wafer W is irradiated from the laser beam irradiation head 3 to the back surface W2 side of the wafer W, and the laser beam 3a is irradiated into the wafer W. Collect light. The laser beam 3a is irradiated along the division line L shown in FIG. 1 while moving the wafer W together with the support member 1 in the front-rear direction in FIG. As a result, the altered layer C is formed inside the wafer W. This altered layer C is a starting point when cutting by applying an external force later, and any one of density, refractive index, mechanical strength and other physical characteristics is different from the surrounding area. It is a layer and includes, for example, a melt treatment region, a crack region, a dielectric breakdown region, a refractive index change region, and the like, and there is a region in which these are mixed. This altered layer C is formed along all the division lines L shown in FIG.

(4) Expanding tape sticking step (Step S4)
Next, as shown in FIG. 7, the expanded tape T is attached to the back surface W2 of the wafer W on which the deteriorated layer forming step has been performed. The expanded tape T is configured by applying an adhesive layer to one surface of a sheet base material made of, for example, polyvinyl chloride, and is formed to be stretchable. An annular frame F is attached to the peripheral portion of the expanded tape T, and the wafer W is integrated with the frame F via the expanded tape T.

(5) Support member removal step (step S5)
When the support member 1 is formed of a material that transmits ultraviolet rays, such as glass, and the adhesive 2 is made of an ultraviolet curable resin, the support member 1 side is shown in FIG. Then, the adhesive 2 is cured by irradiating with ultraviolet rays to reduce the adhesive strength. And after the adhesive force of the adhesive agent 2 falls, as shown in FIG. 9, the support member 1 is peeled and removed. Since the device region Wa is not attached to the support member, the device is not damaged at the time of removal.

(6) Tape expansion step (step S6)
After the support member removing step, as shown in FIG. 10, the tape T side is placed on the holding table 40 of the tape expansion device 4, and the frame F is held by the frame holding portion 41. The frame holding portion 41 is fixed to a piston 43 driven by a cylinder 42 and is configured to move up and down together with the piston 43. In the tape expansion step, the frame holding unit 41 and the holding table 40 are relatively moved in the vertical direction so that the frame holding unit 41 is relatively lowered in relation to the holding table 40 as shown in FIG. Then, the tape T is stretched and expanded by the descending frame F, so that an external force in the horizontal direction acts on the deteriorated layer C. Therefore, the wafer W is broken in the deteriorated layer C and divided into individual devices D. The

  As described above, since the wafer W is held in a state where the device region Wa is not in contact with the support member 1 in the fixing step, there is no possibility that the device is damaged when the support member is removed from the wafer in the support member removing step. Therefore, in the tape expansion step, individual devices without damage can be obtained.

[2] Second Embodiment As a second embodiment, instead of the adhesive 2 made of the ultraviolet curable resin used in the first embodiment, as shown in FIG. The case where the adhesive 2a other than the ultraviolet curable resin is used will be described.

  The support member preparation step (step S1) is performed in the same manner as in the first embodiment. The next fixing step (step S2) is also performed in the same manner as in the first embodiment except that the type of adhesive is different.

  In the deteriorated layer forming step (step S3), as shown in FIG. 12, the deteriorated layer C is formed inside the wafer W along the planned division line, and the wafer W and the laser light irradiation head 3 are relatively rotated. Then, from the back surface W2 side, along the boundary portion Wab between the device region Wa and the outer peripheral surplus region Wb, the laser beam irradiation head 3 irradiates the laser beam 3b having transparency to the wafer W, and The light is condensed inside, and the altered layer Cab is formed inside the wafer W along the boundary portion Wab.

  After performing the expand tape attaching step (step S4) in the same manner as in the first embodiment, in the support member removing step (step S5), as shown in FIG. 13, for example, the inner diameter is substantially equal to the outer peripheral surplus area Wb. The hard ring member is pressed from the expanded tape T side to break along the deteriorated layer Cab shown in FIG. 12 and separated into the device region Wa and the outer peripheral surplus region Wb, and then the support member 1 and the adhesive The outer peripheral surplus area Wb is removed together with 2a.

  Thereafter, the tape expansion step (step S6) is performed in the same manner as in the first embodiment, and each device D is divided. Also in the second embodiment, since the wafer W is held in a state where the device region Wa is not in contact with the support member 1 in the fixing step, the device may be damaged when the support member is removed from the wafer in the support member removing step. There is no. Thus, individual devices without damage can be obtained in the tape expansion step.

W: Wafer W1: Front surface W2: Back surface Wa: Device region Wb: Peripheral surplus region Wab: Boundary portion L: Line to be divided D: Device C, Cab: Altered layer T: Expanded tape F: Frame 1: Support member 10a: Concave portion 10b: outer peripheral part 2, 2a: adhesive 3: laser light irradiation head 3a, 3b: laser light 4: tape expansion device 40: holding table 41: frame holding part

Claims (2)

Wafer dividing method for dividing a wafer in which a plurality of micromachine devices are partitioned by a line to be divided and an outer peripheral surplus area surrounding the device area into individual micromachine devices along the line to be divided Because
A support member preparing step of forming a recess having a size corresponding to the device region of the wafer on the surface of the support member having the same diameter as the wafer or a larger outer diameter than the wafer;
After the support member preparation step, the device region of the wafer faces the concave portion, the wafer is placed on the surface of the support member, and an adhesive is applied to the outer peripheral surplus region and the outer peripheral portion of the support member. A fixing step of fixing the outer peripheral surplus region of the wafer to the outer peripheral portion of the support member;
After the fixing step, a laser beam having transparency to the wafer is irradiated from the back side of the wafer along the planned division line, and a deteriorated layer is formed along the planned division line inside the wafer. An altered layer forming step,
An expanded tape attaching step for attaching an expanded tape attached to an annular frame on the back surface of the wafer on which the altered layer forming step has been performed;
A support member removing step of removing the support member from the surface of the wafer after the expanding tape attaching step;
A tape expanding step of breaking the wafer along the planned dividing line by expanding the expanded tape after the support member removing step;
Wafer dividing method including: In the deteriorated layer forming step, a deteriorated layer is formed in the wafer along the planned dividing line, and the wafer is permeable along a boundary portion between the device region and the outer peripheral surplus region. Irradiate laser light from the back side of the wafer, and form a deteriorated layer inside the wafer along the boundary,
In the support member removing step, the wafer is broken along a deteriorated layer formed along the boundary portion, and the outer peripheral surplus region of the wafer fixed to the support member together with the support member is removed from the expanded tape. Remove,
The wafer dividing method according to claim 1.

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