JP2019012718A - Crystal substrate and crystal substrate processing method - Google Patents

Abstract

To provide a crystal substrate and a crystal substrate processing method capable of forming a processed layer by arranging a processing trace at a constant depth position inside a substrate up to the vicinity of the side surface of the substrate by irradiating with a laser beam.SOLUTION: A crystal substrate 20 is used when a processed layer 32 is formed inside a substrate by relatively moving the converging position and the substrate while converging a laser light from the irradiated surface 20r which is one of substrate surfaces into the inside of the substrate. A substrate side surface 20s is inclined toward the central axis side of the substrate from the irradiated surface 20r to the surface opposite to the irradiated surface 20r at an inclination angle α within a predetermined range with respect to the central axis of the substrate .SELECTED DRAWING: Figure 2

Description

  The present invention relates to a crystal substrate and a crystal substrate processing method used when forming a processed layer inside a substrate.

  It has been proposed to focus a laser beam on a crystal substrate to be processed (for example, a single crystal substrate) to form a two-dimensional processed layer and to peel the processed layer from the processed layer.

  By peeling from the processed layer in this manner, a predetermined thin substrate can be obtained (for example, see Patent Document 1).

JP 2012-020222 A

  By the way, since the substrate side surface is cylindrical in the conventional crystal substrate, it is necessary to irradiate a part of the laser light from the substrate side instead of the irradiated surface when forming a processing mark near the substrate side surface. Accordingly, the formation accuracy of the processing marks near the side surface of the substrate is inferior to other processing marks. That is, the laser beam condensing position is shifted near the substrate side surface, so that the processed layer cannot be formed uniformly up to the substrate side surface (particularly, the shape and depth position cannot be fixed). For this reason, substrate peeling cannot be performed well.

  In view of the above problems, the present invention provides a crystal substrate that can be formed into a processing layer by irradiating laser light and arranging processing marks at a constant depth position inside the substrate up to the vicinity of the side surface of the substrate, and It is an object to provide a crystal substrate processing method.

  According to one aspect of the present invention for solving the above-described problem, the laser light is condensed from the irradiated surface, which is one of the substrate surfaces, into the substrate, and the condensing position and the substrate are relatively moved. A crystal substrate used when forming a processed layer inside a substrate, wherein the substrate side surface is inclined toward the substrate central axis from the irradiated surface to a surface opposite to the irradiated surface. A crystal substrate is provided that is inclined at an inclination angle within a predetermined range with respect to the central axis.

  The irradiated surface may have a rectangular shape, and the substrate side surface may extend from each side of the irradiated surface.

  The irradiated surface may be circular and the substrate side surface may be a truncated cone surface.

  According to another aspect of the present invention for solving the above-described problem, a substrate preparing step of preparing the crystal substrate according to one embodiment of the present invention, and the crystal substrate prepared in the substrate preparing step of the laser beam An arrangement step of disposing laser condensing means for condensing laser light on the irradiated surface in a non-contact manner at an irradiated position, and a laser beam emitted from the laser condensing means While irradiating so that the central axis is orthogonal to the irradiated surface and entering from the irradiated surface and condensing the laser light inside the crystal substrate, the laser condensing means and the crystal substrate are relatively Forming a processed layer in which processing marks are arranged inside the crystal substrate by moving the laser, and the inclination angle is α, and the laser from the irradiated surface to the condensing point in the crystal substrate The beam side, which is the outermost surface of light, is the substrate When the angle formed with respect to the mandrel and beta, in the forming step crystal substrate processing method for preparing the crystalline substrate in the substrate preparing step so as to satisfy the relationship of alpha ≧ beta is provided.

  Further, in the forming step, when the edge machining trace is formed, the edge machining trace is formed by measuring the distance from the edge machining trace located at the edge of the machining layer to the side surface of the substrate along the machining layer. The crack generated from the trace may be within a range in which the crack can reach the side surface of the substrate along the processed layer.

  Further, in the forming step, a correction ring may be provided in the laser condensing means, and the processed layer may be formed while correcting the aberration with the correction ring.

  According to the present invention, there is provided a crystal substrate and a crystal substrate processing method capable of improving the formation accuracy of a processing mark formed near the side surface of a substrate when a processing layer is formed in the substrate by irradiating a laser beam. can do.

(A) is a typical perspective view which shows the structure of the substrate processing apparatus used with the crystal substrate processing method which concerns on one Embodiment of this invention, (b) is arrange | positioned at the laser condensing means of this substrate processing apparatus. It is a typical side view explaining a lens. It is a typical side view explaining forming a processing layer in a crystal substrate concerning one embodiment of the present invention with a crystal substrate processing method concerning one embodiment of the present invention. It is a typical side view explaining the modification of forming a processing layer in a crystal substrate by condensing a laser beam with a crystal substrate processing method concerning one embodiment of the present invention. It is a typical perspective view explaining the modification of the crystal substrate which concerns on one Embodiment of this invention. It is a typical side view explaining the prior art example of forming a process layer in a crystal substrate. It is a typical side view explaining the comparative example of forming a processed layer in a crystal substrate.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following description, the same or similar components as those already described are denoted by the same or similar reference numerals, and detailed description thereof is omitted as appropriate. The following embodiments are exemplifications for embodying the technical idea of the present invention, and the embodiments of the present invention are described below in terms of the material, shape, structure, arrangement, etc. of the components. It is not something specific. The embodiments of the present invention can be implemented with various modifications without departing from the scope of the invention.

  1A is a schematic perspective view showing a configuration of a substrate processing apparatus used in a crystal substrate processing method according to an embodiment of the present invention (hereinafter referred to as this embodiment), and FIG. It is a typical side view explaining the lens arrange | positioned at the laser condensing means of this board | substrate processing apparatus. FIG. 2 is a schematic side view for explaining that a processed layer is formed in a crystal substrate by condensing laser light in the crystal substrate processing method according to one embodiment of the present invention.

  The substrate processing apparatus 10 includes a mounting table 12, a substrate holder 13 that is fixed on the mounting table 12, and holds a crystal substrate (for example, a single crystal substrate such as SiC), and the Z direction (vertical direction) of the mounting table 12. A Z stage 14 that is movably supported at a position, a Y stage 16 that supports the Z stage 14 so as to be movable in the Y direction, and an X stage 18 that supports the Y stage 16 so as to be movable in the X direction are provided.

  In addition, the substrate processing apparatus 10 includes laser condensing means 22 (for example, a concentrator) that condenses the laser light B toward the crystal substrate 20 held on the substrate holder 13. Laser light emitted from the laser oscillation device is incident on the laser condensing means 22.

  The laser condensing means 22 includes a correction ring 24, a condensing lens 26 held in the correction ring 24 (for example, a first lens 28 that condenses in the air, and the first lens 28 and the crystal substrate 20). Lens having a second lens 30 disposed between them, and has a function of correcting an aberration caused by the refractive index of the crystal substrate 20, that is, a function as an aberration correction ring. Specifically, as shown in FIG. 1B, when the condenser lens 26 is condensed in the air, the laser beam B reaching the outer peripheral portion E of the condenser lens 26 is reflected by the condenser lens 26. Correction is performed so that the laser beam B that has reached the center M is condensed on the condenser lens side. That is, when the light is condensed, the condensing point EP of the laser light B reaching the outer peripheral portion E of the condensing lens 26 is compared with the condensing point MP of the laser light B reaching the central portion M of the condensing lens 26. Correction can be made so that the position is close to the condenser lens 26. Thereby, the length in the laser irradiation direction of the processing mark C formed by condensing the laser light can be shortened, that is, the thickness of the processing layer 32 (described later) can be easily reduced.

(Crystal substrate)
The crystal substrate 20 according to the present embodiment forms the processing layer 32 in the substrate by relatively moving the condensing position and the crystal substrate while condensing the laser beam B from the irradiated surface 20r into the substrate. It is a crystal substrate used in the case.

  The crystal substrate 20 has a substrate side surface 20s inclined toward the substrate central axis G from the irradiated surface 20r to the surface opposite to the irradiated surface 20r, and inclined within a predetermined range with respect to the substrate central axis G. It is inclined at an angle α. This inclination angle is determined on the assumption of an angle β described later. The angle β may be assumed in advance over a plurality of values, and each α may be determined so as to correspond to each value of the angle β.

  In the present embodiment, the irradiated surface 20r is rectangular. And this board | substrate side surface 20s extended from each edge | side of the to-be-irradiated surface 20r inclines at the said inclination angle inside a board | substrate. The substrate side surface 20s is formed by, for example, grinding obliquely in this way.

  Hereinafter, the crystal substrate processing method according to the present embodiment will be described.

  In this embodiment, a substrate preparation process for preparing the crystal substrate 20 is performed. In this substrate preparation step, an angle (beam side surface angle) formed by the beam side surface Bs which is the outermost surface of the laser light from the irradiated surface 20r to the condensing point in the crystal substrate 20 with respect to the substrate center axis G (see FIG. 1). ) Is β, a crystal substrate 20 satisfying the relationship of α ≧ β is prepared. For example, as shown in FIG. 2, a crystal substrate 20 is prepared such that α and β are equivalent in the above relationship.

  Next, an arrangement process is performed. In this arrangement step, the crystal substrate 20 prepared in the substrate preparation step is arranged at the irradiated position of the laser beam B, and the laser condensing means 22 for condensing the laser beam B is arranged on the irradiated surface 20r in a non-contact manner. . In the present embodiment, the crystal substrate 20 is held at the irradiated position by holding the crystal substrate 20 on the substrate holder 13 on the mounting table 12.

  And a formation process is performed. In this forming step, the laser beam B emitted from the laser focusing means 22 is all irradiated so that the beam center axis Bc of the laser beam B is perpendicular to the irradiated surface 20r and incident from the irradiated surface 20r. The processing layer 32 is formed inside the crystal substrate 20 by relatively moving the laser focusing means 22 and the crystal substrate 20 while condensing the laser beam B inside the crystal 20. In the present embodiment, in the forming step, the laser condensing means 22 and the crystal substrate 20 are relatively moved in the XY plane (in the two-dimensional plane), so that the predetermined depth d from the irradiated surface 20r. A processing layer 32 in which processing marks C are arranged at a predetermined dot pitch DP and line pitch is formed at the position.

  Therefore, as shown in FIG. 2, even when the edge processing mark Ce located at the edge (outer edge) of the processing layer 32 in the processing mark C is formed near the substrate side surface 20s (near the substrate end surface), the laser All the laser light B emitted from the condensing means 22 is incident on the irradiated surface 20r, and a part of the laser light B is prevented from entering from the substrate side surface 20s.

  Therefore, there is provided a crystal substrate 20 and a crystal substrate processing method capable of forming the processing layer 32 by arranging the processing marks C at positions with a constant depth d inside the substrate up to the vicinity of the substrate side surface 20s (near the substrate end surface). Realized. And when peeling from such a processed layer 32, it can peel easily without processing the board | substrate side surface 20s, and a peeling board | substrate can be obtained.

  Further, the edge processing mark Ce can be formed in the vicinity of the substrate side surface 20s with the same forming accuracy as the processing mark C formed in the central portion of the substrate, and further, with the same forming accuracy even at a position extremely close to the substrate side surface 20s. The edge processing mark Ce can be formed, and the forming accuracy is greatly improved as compared with the conventional case.

  Further, the laser condensing means 22 includes a correction ring 24 and a condensing lens 26 held in the correction ring 24, and a function of correcting aberration caused by the refractive index of the crystal substrate 20, that is, aberration correction. It functions as a ring. The processing layer 32 may be formed while correcting aberrations using such a function, which makes it easy to shorten the length in the laser irradiation direction of the processing mark C formed by condensing the laser beam B. That is, it is easy to reduce the thickness of the processed layer 32.

  In the substrate preparation step, β is assumed in advance over a plurality of values, each α is determined so as to correspond to each value of β, and a plurality of types of crystal substrates 20 (crystal substrates having different αs) are prepared in advance. Alternatively, a crystal substrate corresponding to the actual β may be selected. As a result, the time required for the substrate preparation process can be greatly reduced.

  Further, in the forming step, the distance W from the edge processing mark Ce to the substrate side surface 20s along the processing layer 32 is set to the crack K generated from the edge processing mark Ce when the edge processing mark Ce is formed (FIGS. 2 and 3). May be within a range that can reach the substrate side surface 20s along the processed layer 32 (in this case, it can also be seen that the processing marks C are continuously formed up to the substrate side surface 20s). Thereby, peeling from the processed layer 32 is remarkably easy, and it is also possible to perform natural peeling simultaneously with completion of the formation of the processed layer 32.

  2 shows an example in which a crystal substrate 20 in which α and β are equal is shown, but as shown in FIG. 3, a crystal substrate 36 having α larger than β may be prepared. Good. Even in this case, the same effect can be obtained.

  Further, instead of the crystal substrate 20, a frustoconical crystal substrate 40 as shown in FIG. 4 may be used. In this case, the substrate side surface 40s of the crystal substrate 40 has a truncated conical surface shape whose diameter gradually decreases from the circular irradiated surface 40r to the surface opposite to the irradiated surface 40r. The substrate side surface 40s is formed by grinding in a tapered shape.

  Even when processing marks are formed near the substrate side surface 40s (near the substrate end surface) using such a crystal substrate 40 (that is, when the edge processing marks Ce are formed), the laser emitted from the laser focusing unit 22 is emitted. All the light B is incident on the irradiated surface 40r, and a part of the laser light B is prevented from entering from the substrate side surface 40s. Therefore, the same effect as when the crystal substrate 20 is used can be obtained.

<Examination example>
FIG. 5 is a schematic side view for explaining a conventional example of forming a processed layer in a crystal substrate by condensing laser light. FIG. 6 is a schematic side view illustrating a comparative example of forming a processed layer in a crystal substrate by condensing laser light.

  As shown in FIG. 5, in the conventional crystal substrate 80, the substrate side surface is cylindrical. Therefore, in the irradiation mode in which all the laser light B emitted from the laser focusing means 22 is incident on the irradiated surface 40r, the edge of the processed layer A processing mark (edge processing mark Ce or the like) cannot be formed in the vicinity of the substrate side surface 80s (near the substrate end surface). When forming a processing mark in the vicinity of the substrate side surface 80s, it is necessary to irradiate a part of the laser beam B from the substrate side surface 80s instead of the irradiated surface 80r. The formation accuracy is greatly inferior compared to the above embodiment. Further, when the irradiation from the substrate side surface 80s is not performed, an unprocessed portion where a processing mark is not formed is generated in the vicinity of the substrate side surface 80s.

  Further, as shown in FIG. 6, in the crystal substrate 90 of the comparative example, the relationship between α and β is α <β and α ≧ β is not satisfied. Therefore, as in the conventional example, when forming a processing mark (edge processing mark Ce or the like) in the vicinity of the substrate side surface 90s (in the vicinity of the substrate end surface), a part of the laser beam B is not the irradiated surface but the substrate side surface 90s. Therefore, the formation accuracy of processing marks (edge processing marks Ce and the like) is greatly inferior to that of the above embodiment. Further, when the irradiation is not performed from the substrate side surface 90s, an unprocessed portion where a processing mark is not formed is generated in the vicinity of the substrate side surface 90s.

  On the other hand, in the above embodiment, even when the edge processing mark Ce is formed in the vicinity of the substrate side surface 20s and further in a position extremely close to the substrate side surface 20s, all the laser light B incident on the crystal substrate 20 is irradiated. It can enter from the surface 20r, and it is avoided that a part of laser beam B enters from the substrate side surface. Therefore, the processing layer 32 can be formed by arranging the processing marks C at positions of a constant depth d inside the substrate up to the vicinity of the substrate side surface 20s. In addition, the edge processing mark Ce can be formed in the vicinity of the substrate side surface 20s with the same forming accuracy as the processing mark formed in the central portion of the substrate, and further, with the same forming accuracy even at a position extremely close to the substrate side surface 20s. The edge processing mark Ce can be formed, and an unprocessed portion where no processing mark is formed does not occur in the vicinity of the substrate side surface 20s.

  According to the present invention, the processing layer can be formed at a certain depth position to the substrate side surface by relatively moving the condensing position and the substrate while condensing the laser beam inside the substrate. Can be easily peeled off to obtain a peeled substrate. For example, if it is a single crystal substrate and an Si substrate (silicon substrate), it can be applied to solar cells, and a sapphire substrate such as a GaN-based semiconductor device. Can be applied to light emitting diodes, laser diodes, etc., SiC can be applied to SiC power devices, etc., and can be applied in a wide range of fields such as transparent electronics, lighting, and hybrid / electric vehicles. Is possible.

10 Substrate Processing Device 13 Substrate Holder (Substrate Holder)
12 Mounting stage 14 Z stage 16 Y stage 18 X stage 20 Crystal substrate 20r Irradiated surface 20s Substrate side surface 22 Laser condensing means 24 Correction ring 26 Condensing lens 28 First lens 30 Second lens 32 Work layer 36 Crystal substrate 40 Crystal Substrate 40r Irradiated surface 40s Substrate side surface 80 Crystal substrate 80s Substrate side surface 80r Irradiated surface 90 Crystal substrate 90s Substrate side surface B Laser beam Bc Beam center axis Bs Beam side surface C Processing mark Ce Edge processing mark G Substrate axis K Crack E Outer part EP Condensing point M Center part MP Condensing point W Distance α Inclination angle β Angle

Claims (6)

A crystal substrate used to form a processing layer inside a substrate by concentrating the laser beam from the irradiated surface, which is one substrate surface, to the inside of the substrate while relatively moving the condensing position and the substrate. And
The substrate side surface is inclined toward the substrate central axis side from the irradiated surface to the surface opposite to the irradiated surface, and is inclined at an inclination angle within a predetermined range with respect to the substrate central axis. A featured crystal substrate. The irradiated surface is rectangular,
The crystal substrate according to claim 1, wherein the substrate side surface extends from each side of the irradiated surface. The irradiated surface is circular,
The crystal substrate according to claim 1, wherein the substrate side surface has a truncated cone shape. A substrate preparing step of preparing the crystal substrate according to claim 1;
An arrangement step in which the crystal substrate prepared in the substrate preparation step is arranged at a position to be irradiated with laser light, and a laser condensing means for condensing the laser light is arranged in a non-contact manner on the irradiated surface;
All of the laser light emitted from the laser condensing means is irradiated so that the center axis of the laser light is perpendicular to the irradiated surface and incident from the irradiated surface, thereby condensing the laser light inside the crystal substrate. And forming a processing layer in which processing marks are arranged inside the crystal substrate by relatively moving the laser condensing means and the crystal substrate, and
If the tilt angle is α, and the angle formed by the beam side surface, which is the outermost surface of the laser beam from the irradiated surface to the condensing point in the crystal substrate, with respect to the central axis of the substrate is β, A crystal substrate processing method comprising preparing the crystal substrate in the substrate preparation step so as to satisfy a relationship of ≧ β.   In the forming step, the distance from the edge processing trace located at the edge of the processing layer to the side surface of the substrate along the processing layer is determined from the edge processing trace when the edge processing trace is formed. The crystal substrate processing method according to claim 4, wherein the generated crack is within a range in which the generated crack can reach the side surface of the substrate along the processed layer.   6. The crystal substrate processing method according to claim 4, wherein in the forming step, a correction ring is provided in the laser condensing means, and the processed layer is formed while correcting aberrations by the correction ring.

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