JP2006245498A - Process and apparatus for producing substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a thin substrate from an ingot without producing any chip. <P>SOLUTION: A money belt-like cut 9 is made by irradiating the side face of a columnar ingot 1 with a laser beam 10 from the side and the condensing point of a laser beam 4 from the longitudinal direction of the ingot 1 is aligned along the cut 9 to form a machining area by multiphoton absorption from the cut 9 of the ingot 1 toward the interior. A part of the ingot 1 is stripped using the machining region as a strip plane to obtain a substrate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a substrate and an apparatus therefor, and more specifically, a side surface of a columnar ingot is irradiated with laser light from the side to form a notch in a cylindrical shape, and one of the ingots is formed along the notch. The present invention relates to a method for manufacturing a substrate and an apparatus therefor, which are obtained by peeling a portion to obtain a substrate.

  As a method of manufacturing a substrate from an ingot, for example, a process of cutting a wafer used for manufacturing a semiconductor device from a cylindrical or prismatic ingot made of a crystal such as Si or GaAs can be cited. As a method of cutting a wafer from such an ingot, there is a method of physically cutting the ingot with a diamond blade saw or a wire saw. Diamond blade saws take a long time to cut, and are currently mainstream because multiple wire saws can be used simultaneously to cut multiple wafers from an ingot.

However, with this cutting method, it is difficult to obtain a thin wafer of 100 μm or less, and there is a lot of waste in the machining allowance during processing.
For this reason, in order to minimize waste of the ingot as much as possible, the excimer laser device that continuously oscillates the ultraviolet excimer laser light and the condensing optical system that condenses and irradiates the excimer laser light on the surface of the crystal ingot are provided. Crystal ingot cutting devices that cut perpendicularly to the longitudinal direction are known.

In this crystal ingot cutting device, a continuous oscillation of excimer laser light is focused on the surface of the crystal ingot to locally raise the temperature and cleave by thermal stress. A substrate is created by cutting vertically (see, for example, Patent Document 1).
JP 2002-184724 A

However, in the cutting method proposed in the above publication, when the crystal is highly cleaved, such as mica, it can be easily cut on the surface, but silicon or the like has a low cleaveability and cuts on the surface. It is difficult.
In view of such a problem, an object of the present invention is to obtain a thin substrate from a crystal ingot without chips.

  The present invention forms a notch in a cylindrical shape on the side surface of a columnar ingot, and aligns the condensing point of the laser light from the longitudinal direction of the ingot along the notch, thereby making a multiphoton from the notch of the ingot toward the inside. Provided is a substrate manufacturing method comprising forming a processed surface region by absorption, separating a part of an ingot using the processed surface region as a release surface, and obtaining a substrate.

  According to the present invention, first, a notch is formed in the side surface of the columnar ingot, and then the condensing point of the laser beam is aligned along the notch from the longitudinal direction of the ingot, so that the ingot is directed from the notch toward the inside. Thus, a processed surface region by multiphoton absorption is formed, and a part of the ingot is peeled using this processed surface region as a peeled surface, so that a thin substrate can be easily obtained without chips even from an ingot with low cleavage property.

In the method for manufacturing a substrate according to the present invention, first, a notch is formed in a cylindrical shape on the side surface of a columnar ingot.
Here, as the columnar ingot, single crystal or polycrystalline ingots such as silicon (Si) and GaAs are targeted. Then, a notch is formed on the side surface of the columnar ingot in a body-wound shape (not necessarily the entire circumference).

  This notch can be formed by irradiating laser light from the side of the ingot, but it is along the cleavage plane of the ingot [for example, the (100) plane, (111) plane, (110) plane, etc. of silicon). preferable. Further, the notches on the side surfaces of the columnar ingot can be formed using a dicing apparatus.

As the laser light, a YAG laser, an excimer laser, or the like can be used. The depth of the notch (notch groove) is 1 to 100 μm, preferably 1 to 50 μm.
In the present invention, a processing surface region by multiphoton absorption is formed from the notch of the ingot toward the inside by aligning the condensing point of the laser light from the longitudinal direction of the columnar ingot along the notch.

  That is, the ingot is locally heated by multiphoton absorption at the condensing point of the laser beam, and a processing surface region (processing region) is formed inside the ingot 1 by this heating. By forming a processed surface area (processed area) by multiphoton absorption, it becomes easy to cut silicon bonds, and by cutting out the ingot in advance, the direction for peeling can be controlled, and peeling is preferably performed. Thus, the substrate can be easily obtained.

  As the laser beam used here, a YAG laser or the like can be used, but it is particularly preferable to use those pulsed laser beams and to set the pulse width to 1 μs or less. These laser beams are condensed and irradiated not from the side of the columnar ingot but from the longitudinal direction to form a processing surface region (processing region) by multiphoton absorption from the notch of the ingot toward the inside. For example, when the ingot is silicon, the wavelength of the laser light is preferably 800 nm or more.

In the present invention, a part of the ingot is peeled off using the processed surface area as a peeling face to obtain a substrate.
Here, when part of the ingot is peeled off, it is preferable to forcibly separate the part of the ingot from the other part of the ingot by vacuuming or vacuum suction. In addition, it is possible to use an electrostatic chuck, Bernoulli method or the like. it can.

  According to another aspect of the present invention, an ingot holding part for holding a columnar ingot, a first laser light irradiation part for irradiating a side surface of the ingot with laser light from the side, and a longitudinal direction of the ingot A second laser beam irradiating unit for condensing and irradiating the laser beam, and a side surface of the ingot is irradiated with the laser beam from the side by the first laser beam irradiating unit, and a notch is formed in a cylindrical shape on the side surface of the ingot Then, in order to form a processing surface region by multiphoton absorption from the notch of the ingot toward the inside by aligning the condensing point of the laser light from the longitudinal direction of the ingot by the second laser light irradiation unit along the notch, A sweeping means for moving the ingot holding unit, the first laser beam irradiating unit and the second laser beam irradiating unit relatively to sweep each laser beam with respect to the ingot; It can be provided an apparatus for manufacturing a substrate having a release means for obtaining exfoliated substrate part of the ingot as the release surface.

  Here, the sweeping means rotates the ingot holding portion to rotate the cylindrical ingot around its longitudinal axis and intermittently move in parallel to the longitudinal axis, and parallel to the rotational axis. First moving means for intermittently moving, and the second laser beam irradiation unit to be centrically and backwardly directed to the rotation center axis of the ingot holding unit in order to move the ingot in the centroidal and backward directions about its longitudinal axis When the second moving means for moving in the direction is used, the relative movement of the ingot holding unit, the first laser beam irradiation unit, and the second laser beam irradiation unit is simplified, and each laser beam can be easily transmitted to the ingot. It is preferable because it can be swept.

  Further, the sweeping means rotates the cylindrical ingot around its longitudinal axis, intermittently moves it parallel to the longitudinal axis of the ingot, and rotates the center of the ingot holding part with respect to the second laser light irradiation part. In order to move the shaft in the centripetal and backward directions, the ingot holding portion is rotated, and the ingot holding portion is intermittently moved in parallel with the rotating shaft, and the central axis of rotation of the ingot holding portion with respect to the second laser light irradiation portion If the third moving means for moving the laser beam in the centripetal and backward directions is used, it is not necessary to move the complicated and bulky first and second laser light irradiation units, and thus sweeping becomes extremely easy.

  In the present invention, the peeling means is preferably a suction means (for example, a vacuum chuck) for forcibly separating a part of the ingot from the other part of the ingot by vacuum or vacuum suction. In addition, an electrostatic chuck, Bernoulli method, etc. Can be used.

FIG. 1 is a schematic configuration explanatory view showing an embodiment of a manufacturing apparatus for carrying out a substrate manufacturing method according to the present invention, and FIG. 2 is a configuration explanatory view showing a first laser light irradiation unit more specifically. FIG. 3 is a structural explanatory view showing the second laser light irradiation section more specifically, and FIG. 4 is a structural explanatory view showing the peeling means more specifically.
In the following description, a plane parallel to the machining surface formed inside the cylindrical ingot 1 is referred to as a horizontal plane (XY plane), and a vertical direction is referred to as a vertical direction (Z direction).

  In FIG. 1, an ingot cutting device 3 as a substrate manufacturing apparatus includes a first laser beam irradiation unit 10, and the first laser beam irradiation unit includes a notch laser device 10 a and a notch laser device 10 a. It comprises a notch condensing lens 12 that condenses the oscillating laser beam 11. The notch laser device 10a and the notch condensing lens 12 are provided on the ingot cutting device 3 so as to be movable in the vertical direction (Z direction).

Further, the ingot cutting device 3 includes a second laser light irradiation unit 4, and the second laser light irradiation unit is configured to move a laser device 4a movable in the XYZ directions and a laser beam 5 oscillated from the laser device 4a. Condensing lens 6 consists of a condensing lens 6 that can move and move similarly to laser device 4a.
Here, the ingot 1 has a cylindrical shape and is mounted on a rotation stage 7 (ingot holding portion) that can rotate (turn). A motor 13 is directly connected to the rotary stage 7.

Further, the ingot cutting device 3 includes a rotary stage 7, a first laser light irradiation unit 10 (including a notch laser device 10a and a notch condensing lens 12), and a second laser light irradiation unit 4 (with the laser device 4a). Sweeping means (not shown in FIG. 1) for moving each laser beam with respect to the ingot 1 is provided. In addition, 8 is the peeling means mentioned later.
In FIG. 2, the first laser beam irradiation unit 10 houses a notch laser device 10 a, a notch condensing lens 12, and the notch laser device 10 a and the notch condensing lens 12. The sweep unit mainly composed of the cylindrical body 10b and sweeping the first laser light irradiation unit 10 includes a stage 14 for moving the cylindrical body 10b in the vertical direction (Z direction) and a linear motor (not shown).
In FIG. 3, the second laser light irradiation unit 4 mainly includes a laser device 4 a, a condenser lens 6, and a cylindrical body 6 b that houses the laser device 4 a and the condenser lens 6. And the sweep means which sweeps the 2nd laser beam irradiation part 4 raises the base stage 15 and the linear motor (illustration omitted) which raises / lowers the cylinder 6b to an up-down direction (Z direction), and the base stage 15 with the cylinder 6a. And an X-axis stage 16, a Y-axis stage 17, and respective linear motors (not shown) that are moved horizontally (XY directions) with respect to the central axis of the rotary stage 7.

  The focused laser beam 11 is irradiated at a predetermined distance from the horizontal plane of the ingot 1 (from the side). And the laser beam 11 condensed by the rotation of the ingot 1 irradiates the surface (side surface) of the ingot 1 in a body-wound shape (circumferential shape). Here, the laser beam 11 is set to such a power that a notch 9 having a predetermined depth (for example, 1 to 100 μm) is made in silicon so that the ingot 1 is not broken in an unexpected direction. In addition, the surface (side surface) which is an incident surface from the laser apparatus 4 of the ingot 1 is flat.

  Next, the laser beam 5 is condensed and irradiated to the position of the notch from the longitudinal direction of the ingot 1 in which the notch 9 is wound in a body shape (from the upper part of the surface that is the laser incident surface). Due to the rotation of the ingot 1 and the movement of the ingot 1 in the XY directions, the focused laser beam 5 from the laser device 4 is cut from the notch inside the ingot 1 toward the center of the circle when viewed from the top of the surface. Irradiate in a circle.

The laser beam 5 is irradiated within the ingot 1 under the condition that the focusing point is aligned and the electric field intensity at the focusing point is 1 × 10 ⁸ (W / cm ² ) or more and the pulse width is 1 μs or less. Thereby, the inside of the ingot 1 is locally heated by multiphoton absorption. By this heating, a processed surface area (processed area) is formed inside the ingot 1.

  By forming a processed surface area (processed area) by this multiphoton absorption, it becomes easy to cut the silicon bond, and by making a notch in advance, the direction control for peeling can be performed, and peeling is preferably performed. A circular substrate 2 can be easily obtained.

When peeling, it is necessary to handle the peeled wafer so as not to be damaged by means for holding the peeled wafer, for example, a vacuum chuck, electrostatic chuck, Bernoulli method or the like. There is also a method of handling a release wafer by adhering a holding base with an adhesive or attaching a pressure-sensitive adhesive tape or the like. In order to handle a large area substrate without damaging it, it is necessary to hold the entire surface with a uniform holding force.
In the embodiment described above, the ingot cutting device 3 specifically uses a vacuum chuck as the peeling means. That is, in FIG. 4, the peeling means 8 includes a suction portion 8a in which minute suction holes are uniformly and densely formed on the entire holding surface, an arm 8b that supports the suction portion, and a vacuum state of the arm 8b. And a conduit 8c that communicates to the suction portion 8a.
Thus, the silicon bond can be easily cut by the processed surface region (processed region) formed by multiphoton absorption formed in the ingot 1, and the direction for separation can be controlled by making a notch in advance. Peeling is performed and the circular substrate 2 can be easily obtained.

When it is desired to obtain a new substrate, the laser device 10 is lowered by a predetermined width in the Z direction, and a laser beam 11 is irradiated to a place where the laser device 10 is lowered downward, thereby making a notch. Then, the laser device 4 is lowered to irradiate the laser beam 5 at the notch, and then a processing surface region (processing region) is newly formed by multiphoton absorption by bringing the irradiation closer to the central axis of the ingot 1. Then, the new circular substrate 2 is separated by peeling.
In the above example, the laser device 10 is lowered by a predetermined width in the Z direction, and the laser device 4 is also lowered in accordance with the notch position. However, the laser device 10 and the laser device 4 are not lowered by the predetermined width in the Z direction, and the rotation stage The (turntable) may be raised by a predetermined width in the Z direction. Alternatively, the distance of the predetermined width may be maintained by adding the distance in which the laser apparatus 10 and the laser apparatus 4 are lowered in the Z direction and the distance in which the rotary stage is raised in the Z direction.

  As described above, according to the present embodiment, the laser 11 oscillated from the laser device 10 is condensed and cut out, and then the laser light 5 oscillated from the laser device 4 is condensed and ingot 1 is collected. The substrate 2 is separated from the ingot 1 by irradiation. Thereby, there is almost no chip produced from the ingot 1 at the time of peeling, and the material of the ingot is not wasted.

A cylindrical silicon ingot having a diameter of 150 mm was prepared using the apparatus shown in FIG.
Then, as shown in FIG. 1, the laser beam 11 oscillated from the laser device 10 a is condensed on the side surface of the ingot 1 placed on the rotary stage 7 by the condenser lens 12, and the rotary stage 7 is rotated to obtain the depth. A 20 μm cutout 9 was placed at a height of 50 μm from the surface which is the horizontal surface of the ingot. An Nd: YAG harmonic laser was used as the laser. The laser beam 11 was set to such power that a notch was cut into silicon so that the ingot 1 was not broken in an unexpected direction.

  In the apparatus shown in FIG. 1, the laser device 4a is moved above the silicon ingot, focused on a notch formed at a height of 50 μm from the surface that is the horizontal surface of the ingot, the ingot is rotated, and the spot diameter at the focal point Was irradiated with a laser beam of Nd: YAG fundamental wave having a wavelength of 1064 nm and moving from the notch of the ingot to the center.

Since the processed surface area (processed area) is formed inside the ingot 1, it becomes easy to cut the silicon bond, it is suitably peeled off, and the circular substrate 2 can be easily obtained by the arm 8 having the suction mechanism at the tip. I was able to.
In the above embodiment, the substrate having a constant thickness is obtained, but it may be inclined if it has a desired substrate thickness.
In the above description of the embodiments and examples, a silicon ingot is used as an ingot. However, the present invention is not limited to silicon, and can be applied to other crystal ingots such as GaAs ingots.

The method of notching the side surface of the ingot is not limited to the laser device, but may be a dicing device. Further, the rotation stage (rotation table) is rotated and the notches are circumferentially formed on the side surface of the ingot.
In the above description of the embodiment and examples, the ingot is placed on the rotary stage and rotated. However, the ingot is placed on a stage that can also move in the XY directions, and the condensing point of the laser light from the horizontal plane is provided in the notch. While rotating the stage, the stage may be rotated to relatively sweep the laser beam and the ingot to form a processing region, and the substrate may be peeled using this processing region as a peeling surface.

  Here, as the sweeping means, for example, a pair of linear motors that move the stage in the XY direction on the base or a pair of rack and pinion mechanisms, and the rotary stage is rotated on the XY stage and moved up and down. A servo motor to be used, and another linear motor or a rack and pinion mechanism can be used.

  Further, in the description of the above embodiment and examples, the shape of the ingot is described as a cylinder, but the ingot may be a prism (quadrangular prism, pentagonal prism, etc.). In the case of a prism, even if the notch is not on each side, a stage that is notched on one side and moves in the XY direction is aligned with the condensing point of the laser beam from the horizontal plane to the notch. Sweeping may be performed to form a processing region, and the substrate may be peeled using the processing region as a peeling surface.

BRIEF DESCRIPTION OF THE DRAWINGS It is schematic structure explanatory drawing which shows embodiment of the manufacturing apparatus for enforcing the manufacturing method of the board | substrate which concerns on this invention. It is structure explanatory drawing which shows a 1st laser beam irradiation part more concretely. It is structure explanatory drawing which shows a 2nd laser beam irradiation part more concretely. It is structure explanatory drawing which shows a peeling means more concretely.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ingot 2 Circular board | substrate 3 Ingot cutting device 4 Laser apparatus (2nd laser beam irradiation part)
5 Laser beam 6 Condenser lens 7 Rotating stage 8 Arm 9 Notch 10 Notch laser device (first laser beam irradiation unit)
11 Laser beam for notch 12 Condensing lens for notch

Claims (11)

  Forming a cylindrical notch on the side of the columnar ingot and aligning the laser beam focusing point from the longitudinal direction of the ingot along this notch to process the multi-photon absorption from the notch of the ingot toward the inside A method of manufacturing a substrate, comprising: forming a region, separating a part of the ingot using the processed surface region as a separation surface, and obtaining a substrate.   The method for manufacturing a substrate according to claim 1, wherein when forming a processed surface region by multiphoton absorption, a pulse laser beam is used as a laser beam, and a pulse width thereof is set to 1 μs or less.   The method for manufacturing a substrate according to claim 1 or 2, wherein the ingot is made of silicon and the wavelength of the laser beam is set to 800 nm or more when forming a processed surface region by multiphoton absorption.   The method for manufacturing a substrate according to any one of claims 1 to 3, wherein a laser beam is irradiated from a side of the ingot when the notch is formed in a cylindrical shape on a side surface of the ingot.   The method for manufacturing a substrate according to any one of claims 1 to 4, wherein the depth of the notch is 1 to 100 µm.   The manufacturing method of the board | substrate as described in any one of Claims 1-5 which forms the process surface area | region by multiphoton absorption along one of the cleavage surfaces of an ingot.   The method for manufacturing a substrate according to claim 1, wherein when the part of the ingot is peeled off, the part of the ingot is adsorbed and forcibly separated from the other part of the ingot. An ingot holding part for holding a columnar ingot;
A first laser beam irradiation unit for irradiating the side surface of the ingot with the laser beam from the side;
A second laser beam irradiation unit for collecting and irradiating the laser beam from the longitudinal direction of the ingot;
The side surface of the ingot is irradiated with laser light from the side by the first laser light irradiation unit, a notch is formed on the side surface of the ingot, and the longitudinal direction of the ingot is formed by the second laser light irradiation unit along the notch. The ingot holding part, the first laser light irradiation part, and the second laser light irradiation part are relative to each other so as to form a processed surface region by multiphoton absorption from the notch of the ingot toward the inside by aligning the condensing point of the laser light from And sweeping means for sweeping each laser beam with respect to the ingot,
A substrate manufacturing apparatus comprising: a peeling means for peeling a part of an ingot to obtain a substrate by using the processed surface area as a peeling surface.   The sweeping means rotates the ingot holding portion to intermittently move the cylindrical ingot around its longitudinal axis and intermittently move parallel to the longitudinal axis so as to intermittently move the cylindrical ingot parallel to the longitudinal axis. First moving means for moving the second laser beam irradiating portion in the centroid and back directions about the rotation center axis of the ingot holding portion in order to move the ingot in the centroid and back directions about its longitudinal axis The apparatus for manufacturing a substrate according to claim 8, further comprising second moving means for causing the substrate to move.   The sweeping means rotates the cylindrical ingot around its longitudinal axis, intermittently moves it parallel to the longitudinal axis of the ingot, and rotates the central axis of the ingot holding part with respect to the second laser light irradiation part. In order to move in the centripetal and backward directions, the ingot holding part is rotated, and the ingot holding part is intermittently moved in parallel with the rotation axis, and the rotation center axis of the ingot holding part is directed to the second laser light irradiation part. The substrate manufacturing apparatus according to claim 8, comprising third moving means for moving in the direction of the heart and the back.   The substrate manufacturing apparatus according to any one of claims 8 to 10, wherein the peeling unit is a suction unit for forcibly separating a part of the ingot from the other part of the ingot by vacuum or vacuum suction.

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