JP2007012733A - Dividing method of substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method suitable for cutting and dividing a substrate containing a structure jointed using an adhesive, utilizing internal reforming of the substrate due to multiphoton absorption. <P>SOLUTION: The dividing method of a substrate includes a step for removing an adhesive 3 in a planned cutting region by radiating an adhesive removing laser 4 to the adhesive 3, being focused, at the planned cutting region of a substrate 1 on which the adhesive 3 is applied for a structure 2 to be jointed through the adhesive 3. It also includes a step for forming a reformed layer 7 over the entire area of the substrate 1 in thickness direction by radiating an internal reformed layer forming laser 6, from the part where the adhesive 3 is removed, to the inside of the substrate 1 corresponding to the planned cutting line of the substrate 1, being focused, and a step for cutting the substrate 1 comprising the structure 2 by applying a tensile force to the reformed layer 7 of the substrate 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a dividing method using internal modification of a substrate by multiphoton absorption, and more particularly, to a method of dividing various substrates to which a structure is bonded through an adhesive applied on the substrate together with the structure. .

When an element formed on a silicon substrate or a glass substrate is divided into small pieces, since dicing using a rotating grindstone uses water or a grinding liquid, it cannot be applied to dividing a device that does not like wetting. Also, with this method, devices arranged in a zigzag pattern (in different steps) cannot be divided.
On the other hand, when an element formed on a silicon substrate or a glass substrate is divided into small pieces, a modified layer is formed inside the substrate using multiphoton absorption by laser irradiation, and tensile stress is applied to the modified layer. It is known to divide by applying (for example, Patent Documents 1 to 7).

JP 2002-192367 A JP 2002-192368 A JP 2002-192369 A JP 2002-192370 A JP 2002-192371 A JP 2002-205180 A Japanese Patent Laid-Open No. 2002-205181

However, when an adhesive is applied to the substrate and the structure is attached, if the laser is irradiated through the applied adhesive, the laser diffuses due to the unevenness of the adhesive, and the internal modification treatment There is a problem that the partitionability is lowered due to insufficiency. For this reason, when the internal modification is formed by laser and the substrate is divided, the surface of the substrate needs to be a mirror surface, and it is difficult to divide the substrate having a structure bonded with an adhesive.
The present invention has been made in response to the above problems, and a substrate including a structure bonded by an adhesive is cleaved using internal modification of the substrate by multiphoton absorption, and is suitable for division. The purpose is to propose a simple method.

In the substrate dividing method of the present invention, an adhesive removing laser is applied to the adhesive on the surface where the adhesive is applied to the surface and the structure is bonded via the adhesive. And the step of removing the adhesive in the region to be cleaved, and the inside of the substrate corresponding to the planned cleaving line of the substrate from the portion from which the adhesive has been removed. And the step of forming a modified region over substantially the entire region in the thickness direction of the substrate, and applying the tensile force to the modified region of the substrate to provide the structure. And cleaving.
In this method, after removing the adhesive on the substrate with the adhesive removing laser, the internal modified layer forming laser is irradiated from the adhesive removing portion to the inside of the substrate. Thus, a modified region can be formed. Therefore, it is possible to easily divide the substrate provided with the structure by applying a tensile force to the modified region.

  In the substrate dividing method according to the present invention, the first internal modified layer forming laser is irradiated to the inside of the substrate corresponding to the planned cutting line of the substrate together with the focused spot, and the thickness of the substrate is increased. Applying an adhesive to the surface of the substrate on which the non-modified region remains, and a step of leaving a part of the non-modified region on one end side in the direction and making the remaining portion in the thickness direction the modified region Bonding the structure to the substrate through the adhesive; and applying the second internal modified layer forming laser from the adhesive application surface to the non-modified inside the substrate corresponding to the cleaved line Irradiating the region with the focused spot and setting the non-modified region as a modified region; and cleaving the substrate having the structure by applying a tensile force to the modified region of the substrate. With.

  As described above, the laser condensing performance decreases and the workability decreases when the adhesive is applied, but it contributes to cleaving if the light transmitted through the adhesive is within a certain range. It has been found that a sufficient modified layer can be formed. This method uses it. That is, first, a substrate having a non-modified region at one end side in the thickness direction and a remaining region in the thickness direction as a modified region is formed, and the structure is bonded to the substrate with an adhesive. Thereafter, the remaining part of the non-modified region is modified and a tensile force is applied to the modified region, so that the substrate having the structure can be easily divided. As a result, the substrate provided with the structure can be finally divided after various processes such as bonding of the substrate and the structure while avoiding unintentional cleavage of the substrate.

It is preferable that the inside of the substrate is irradiated with the internal modified layer forming laser by gradually shifting the focused spot from the deep portion in the thickness direction to the shallow portion in the thickness direction of the substrate. By doing so, it is possible to form a modified layer of almost the same quality at any part in the thickness direction of the substrate.
Further, it is preferable that the focused spot of each laser is fixed and the substrate is moved so that the focused spot is relatively scanned along the cleaved line. According to this, a general-purpose stage capable of moving the substrate in the plane direction and the rotation direction can be used for laser scanning, and it is not necessary to provide a special mechanism for scanning the laser itself. Further, the movement of the condensing spot can be specialized only for movement in the depth direction of the substrate, that is, focus adjustment.
Irradiation of each laser may be performed by simultaneously irradiating a plurality of locations using a plurality of lasers branched from lasers oscillated from an oscillation source. Thereby, a plurality of locations on the substrate can be processed simultaneously, and the processing efficiency is improved.

The adhesive removing laser is preferably one of an excimer laser, a third harmonic of a YAG laser, a fourth harmonic of a YAG laser, or a CO ₂ laser. These are because they have good absorbability with respect to the polymer material constituting the adhesive.
Moreover, it is preferable that the internal modified layer forming laser is a fundamental wave of a YAG laser. This is because the YAG laser has a strong power and is excellent in terms of a modification action by multiphoton absorption with respect to a silicon substrate or a glass substrate. Therefore, the substrate to be divided in the present invention is preferably either a silicon substrate or a glass substrate.

  Hereinafter, embodiments of the present invention will be described. Although the present invention is a substrate dividing method using internal modification of a member by multiphoton absorption, the internal modification of a member by multiphoton absorption has already been discussed in many academic papers and patent documents. Therefore, the description is omitted here.

Embodiment 1
FIG. 1 is a process diagram showing a processing method according to Embodiment 1 of the present invention. In the method according to the first embodiment, the adhesive 3 is applied over a wide range of the surface of the substrate 1, and one or more structures 2 are bonded to the substrate 1 through the adhesive 3. The present invention can be applied to a structure including one or more independent devices (apparatus or parts) made of the body 2. FIG. 1 shows such a structure (hereinafter referred to as a workpiece 10), and two structures (structural members and mechanical parts) are bonded to a substrate 1 (silicon substrate or glass substrate) via an adhesive 3. 2 including the electronic component), and the substrate 1 and the one structural body 3, and the substrate 1 and the other structural body 3 constitute independent devices.

  Next, a substrate dividing method according to Embodiment 1 will be described with reference to FIG. First, the laser beam 4 for removing the adhesive is applied to the adhesive 3 in the planned cutting area including the planned cutting line of the substrate 1 from the portion of the workpiece 10 where the structure 3 is not present. Are then irradiated (FIG. 1 (a)), and the adhesive 3 at that portion is removed to a predetermined range to form an adhesive removing portion 5 (FIG. 1 (b)). The operation of forming the adhesive removing portion 5 is performed with respect to the entire length of the cutting planned line of the substrate 1 by relatively moving the substrate 1 and the adhesive removing laser 4. In this case, it is preferable that the focused spot of the adhesive removing laser 4 is fixed and the substrate 1 is moved so that the focused spot is relatively scanned along the planned cutting line.

The adhesive removing laser 4 is a laser that has good absorbability with respect to the polymer material constituting the adhesive 3. For example, the excimer laser, the third harmonic of the YAG laser, the fourth harmonic of the YAG laser, and CO _2. Such as a laser. Further, the range of removal of the adhesive 3 is such that, even if the inner modified layer forming laser 6 is irradiated from the adhesive removing portion 5 to the deepest portion of the substrate 1 in the next step, the surrounding adhesive 3 is irradiated with the laser. Not in the size range. Note that, when the width (diameter) of the adhesive removing portion 5 is d1, and the irradiation width (beam diameter) of the internal modified layer forming laser 6 is d2, d1> d2 is set.

Subsequently, the adhesive removal unit 5 irradiates the inner modified layer forming laser 6 with the focused spot inside the substrate 1 corresponding to the planned cutting line of the substrate 1 in the thickness direction of the substrate 1. A modified layer (or modified region) 7 by multiphoton absorption is formed almost all over (FIG. 1C). At this time, it is preferable to irradiate the inside of the substrate 1 with the internal modified layer forming laser 6 by gradually shifting the focused spot from the deep part in the thickness direction of the substrate 1 to the shallow part in the thickness direction.
In addition, irradiation of the internal modified layer forming laser 6 to the inside of the substrate 1 is performed over the entire length of the cleaved line of the laser substrate 1 by relatively moving the substrate 1 and the internal modified layer forming laser 6. In this case, it is necessary to move the focused spot of the internal modified layer forming laser 6 and the substrate 1 relatively, but by fixing the focused spot and moving the substrate 1, the focused spot is cleaved. It is preferable to scan along the line. By doing so, the movement of the focused spot can be specialized only in the movement of the substrate 1 in the depth direction, that is, the focus adjustment.

The internal modified layer forming laser 6 is capable of forming a modified layer that passes through the inside of the base material 1 and absorbs multiphotons inside the substrate 1 to reduce the strength of the substrate 1. . Examples of such a laser include a fundamental wave of a YAG (Nd: YAG) laser, an Nd: YVO ₄ laser, and an Nd: YLF laser. The pulse width is preferably 1 ns or less.
Once the modified layer 7 has been formed over almost the entire length of the substrate 1 in the thickness direction of the substrate 1, the substrate 1 having the structure 2 is modified by applying a tensile force to the modified layer 7. The layer 7 is cleaved (FIG. 1 (d)).

Example 1
(1) Laser irradiation apparatus to be used FIG. 2 is a block diagram showing an example of a laser irradiation apparatus that can be used in the substrate dividing method of the present invention. This laser irradiation apparatus includes a laser oscillator 11 as a laser oscillation source, a Q switch 12 for generating a giant pulse, an attenuator 13 for adjusting laser power, a beam expander 14 for adjusting the laser beam diameter, and a laser beam An electromagnetic shutter 15 that controls blocking and passage, a reflection mirror 16, a condensing lens 17 that condenses the laser, and an autofocus mechanism 18 that adjusts a condensing point (focal position) of the laser light collected by the condensing lens 17, A CCD camera 19 for collecting data for controlling the autofocus mechanism 18, a reticle and illumination 20, an XY stage 21 and a θ stage 22 on which the work 10 to be irradiated is movably mounted, each of the above devices and each A control unit (for example, a personal computer) 30 that controls the operation of the element is provided.
When this illumination device is used, laser scanning for the workpiece 10 is performed by operating the XY stage 21. Further, the angle adjustment of the workpiece 10 is performed by operating the θ stage 22. The position of the laser condensing spot with respect to the thickness direction of the substrate 1 is adjusted by the autofocus mechanism 18.

(2) Processing conditions • Type of substrate 1 and its thickness: silicon substrate, 400 μm
・ Type of adhesive 3 and its thickness: epoxy adhesive, 2 μm
-Adhesive removal laser 4: Excimer laser-Adhesive removal laser 6: YAG (Nd: YAG) laser fundamental wave, frequency 100 kHz, pulse width 30 ns, output 20 μJ / Pulse, intensity of condensing point 1 × 10 ⁸ W / cm ² to 1 × 10 ¹² W / cm ²
・ Laser scan speed: 300mm / s or less

  By using the laser irradiation apparatus of (1) and irradiating the substrate 1 with each laser under the condition of (2), the thickness of the substrate corresponding to the planned cutting line over the entire length of the planned cutting line of the substrate 1. The modified layer 7 that reduces the strength of the substrate 1 could be formed in the entire direction. Thus, the substrate 1 including the structure 2 can be divided from the workpiece 10 by applying an appropriate tensile force to the modified layer 7.

Embodiment 2
FIG. 2 is a process diagram showing a processing method according to Embodiment 2 of the present invention. In the method of the second embodiment, the adhesive 3 is applied over a wide range of the surface of the substrate 1, and one or more structures 2 are bonded to the substrate 1 through the adhesive 3. 2 is used when a component (work 10) including one or more independent devices (apparatus or parts) composed of 2 is manufactured from now on.

  Next, a substrate dividing method according to Embodiment 2 will be described with reference to FIG. First, the first internal modified layer forming laser 6 is irradiated to the inside of the substrate 1 corresponding to the planned cutting line of the substrate 1 together with the focused spot, and unprocessed on one end side in the thickness direction of the substrate 1. Part of the portion (non-modified region) 8 is left, and the remaining portion in the thickness direction is used as a modified layer (modified region) 7 by multiphoton absorption (FIG. 2A). The length of the unprocessed part 8 is about 200 μm. This is because the modification process that contributes to the cleaving is realized at a depth of about 200 μm even through the adhesive 3. Subsequently, the adhesive 3 is applied to the surface of the substrate 1 where the unprocessed portion (unmodified region) 8 remains, and the structure 2 is bonded to the substrate 1 via the adhesive 3 (FIG. 2). (B)). In some cases, after the structure 2 is bonded to the substrate 1, a process for making the structure 2 into a predetermined shape may be performed.

Subsequently, the laser beam 6 for forming the second internal modified layer is irradiated on the unprocessed portion 8 inside the substrate 1 corresponding to the line to be cleaved from the surface where the adhesive 3 is applied together with the focused spot, and the unprocessed The portion 8 is defined as a modified layer (modified region) 7 by multiphoton absorption (FIG. 2C).
The first internal modified layer forming laser 6 and the second internal modified layer forming laser 6 are only separated for convenience of explanation, and they may be lasers having the same mode and the same conditions. The type and the irradiation method may be the same as those of the internal modified layer forming laser 6 of the first embodiment.
Once the modified layer 7 has been formed over almost the entire length of the substrate 1 in the thickness direction of the substrate 1, the substrate 1 having the structure 2 is modified by applying a tensile force to the modified layer 7. The layer 7 is cleaved (FIG. 2 (d)).

Example 2
The laser irradiation apparatus and processing conditions were based on the first embodiment, and a division experiment of the substrate 1 constituting the workpiece 10 was performed. According to this, the modified layer 7 for reducing the strength of the substrate 1 could be formed over the entire length of the planned cutting line of the substrate 1 over the entire area in the thickness direction of the substrate 1 corresponding to the planned cutting line. Thus, the substrate 1 including the structure 2 can be divided from the workpiece 10 by applying an appropriate tensile force to the modified layer 7.

  In the first and second embodiments, a plurality of laser beams obtained by branching the laser oscillated from the laser oscillator 11 with optical elements may be used to irradiate a plurality of locations on the substrate 1 simultaneously. By doing so, a plurality of locations can be processed simultaneously, and the work efficiency of dividing the substrate 1 can be increased.

The substrate to be divided in the present invention is a member capable of multiphoton absorption therein, and among them, a silicon substrate or a glass substrate is the main target. Therefore, the substrate dividing method of the present invention includes a semiconductor substrate constituting various electronic devices, a glass substrate constituting a liquid crystal display device or an EL display device, an electrode substrate constituting a printer inkjet head, and a cavity. It can be applied to the division of a substrate or the like.
The present invention is particularly effective when a substrate that is difficult to be irradiated with a laser beam from the surface opposite to the surface coated with the adhesive is cleaved or divided.

Process drawing which shows the processing method of Embodiment 1 of this invention. Process drawing which shows the processing method of Embodiment 2 of this invention. The block diagram which shows an example of the laser irradiation apparatus which enforces the processing method of this invention.

Explanation of symbols

1 substrate, 2 structure, 3 adhesive, 4 adhesive removal laser, 5 adhesive removal part, 6 internal modified layer forming laser, 7 modified layer, 8 unprocessed part, 10 workpiece.

Claims (8)

An adhesive removal laser is applied to the adhesive to the area where the adhesive is applied to the surface and the structure is bonded via the adhesive. Removing the area adhesive;
From the portion from which the adhesive has been removed, the inner modified layer forming laser is irradiated to the inside of the substrate corresponding to the planned cutting line of the substrate along with its focused spot, and is substantially in the thickness direction of the substrate. Forming a modified region over the entire area;
Cleaving the substrate with the structure by applying a tensile force to the modified region of the substrate;
A method for dividing a substrate, comprising: The first internal modified layer forming laser is irradiated to the inside of the substrate corresponding to the planned cutting line of the substrate along with the focused spot, and one unmodified region is formed on one end side in the thickness direction of the substrate. Leaving the remaining portion in the thickness direction as a modified region;
Applying an adhesive to the surface of the substrate where the non-modified region remains, and bonding the structure to the substrate via the adhesive; and
A second internal modified layer forming laser is irradiated from the adhesive application surface to the unmodified region inside the substrate corresponding to the cleaved line along the focused spot, and the unmodified region is irradiated to the unmodified region. A step of making a reforming region;
Cleaving the substrate with the structure by applying a tensile force to the modified region of the substrate;
A method for dividing a substrate, comprising:   3. The irradiation of the internal modified layer forming laser to the inside of the substrate is performed by gradually shifting the focused spot from the deep portion in the thickness direction to the shallow portion in the thickness direction of the substrate. A method for dividing a substrate as described.   The fixed spot of each laser is fixed, and the substrate is moved so that the focused spot is relatively scanned along the planned cutting line. A method for dividing a substrate according to claim 1.   5. The irradiation of each laser is performed by simultaneously irradiating a plurality of locations on the substrate using a plurality of lasers branched from a laser oscillated from an oscillation source. Substrate dividing method. 6. The substrate division according to claim 1, wherein the adhesive removing laser is one of an excimer laser, a third harmonic of a YAG laser, a fourth harmonic of a YAG laser, and a CO ₂ laser. Method.   7. The substrate dividing method according to claim 1, wherein the internal modified layer forming laser is a fundamental wave of a YAG laser. The substrate dividing method according to claim 1, wherein the substrate is either a silicon substrate or a glass substrate.

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