TW201345640A - Substrate and substrate processing method - Google Patents

Abstract

This invention provides a thin silicon substrate to ensure a production yield. The silicon substrate is a substrate 10 of single-crystal; the substrate 10 has a modified layer 14 in the interior, the modified layer 14 is formed with a periodic structure that has a crystalline orientation different from a crystalline orientation of the substrate 10, and the periodic structures are mutually linked.

Description

Substrate and substrate processing method

The present invention relates to a substrate and a substrate processing method for a single crystal substrate.

In the past, when manufacturing a semiconductor wafer represented by a bismuth (Si) wafer, a molten ingot in a quartz crucible was solidified into an ingot to be cut into a block of an appropriate length ( Block), the peripheral portion is ground to have a target diameter, and then the ingot is sliced into a circular shape by a wire saw to produce a semiconductor wafer. (For example, refer to Patent Documents 1 and 2).

The semiconductor wafer manufactured in this manner is subjected to various processes such as forming a circuit pattern in the preceding step and is supplied to the subsequent step, in which the back surface is subjected to back grind processing in the subsequent step. The thickness is reduced to a thickness of from about 750 μm to less than 100 μm, for example, about 75 μm or about 50 μm.

The conventional semiconductor wafer is manufactured by the above operation, and the ingot is cut by the wire saw, and since the length of the blade is required to be longer than the thickness of the wire saw at the time of cutting, it is extremely difficult to manufacture the thickness of 0.1 mm. The following thin semiconductor wafers also have a problem that the product rate cannot be improved. question.

On the other hand, the disclosed technique combines a collecting aperture of a high numerical aperture with an aberration enhancing material made of a glass plate, and a pulsed laser having a wavelength of 1064 nm on the silicon wafer. After the internal processing, the film is adhered to a rigid substrate and peeled off to obtain a thin single crystal germanium substrate (see Patent Document 3).

According to this technique, a processed layer having a thickness of about 100 μm is formed inside the tantalum substrate. Therefore, when a large number of crystalline substrates are sliced into a thin substrate having a thickness of about 0.1 mm, the yield of the material may be limited. Further, for example, even if the aberration enhancing material for infrared observation is excluded, the thickness of the processed layer cannot be greatly reduced.

Further, in the case of using an objective lens of about NA0.5, the thickness of the processed layer is reduced, but the amount of light is reduced, and the processing of the processed layer cannot be sufficiently performed, and it is difficult to perform actual peeling. On the other hand, when the number of times of irradiation is increased and the processing of the processed layer is sufficiently performed, it is necessary to fill a two-dimensional processing region with a pitch of 1 μm, and a large number of irradiation pulses are required. Practically, there is a problem of irradiation time. .

Further, in this specification, a wafer is generally referred to as a substrate unless otherwise stated.

[Previous Technical Literature]

(Patent Literature)

Patent Document 1: Japanese Patent Laid-Open Publication No. 2008-200772

Patent Document 2: Japanese Laid-Open Patent Publication No. 2005-297156

Patent Document 3: Japanese Laid-Open Patent Publication No. 2011-60862

The present invention has been made in view of the above problems, and an object of the invention is to provide a method for processing a substrate and a substrate, which is an internal processing layer formed by irradiation of laser light inside a crystalline substrate, and a substrate for peeling off using an internal processing layer as a boundary. And the processing method, and the selection of the laser light source is wide, the thickness of the inner processing layer is thin, and the laser beam is irradiated with a small number of laser pulses to effectively form the inner processing layer.

In order to solve the above problems, the substrate according to the present invention is a single crystal substrate having a modified layer formed therein, the modified layer being formed with a periodic structure having a crystal orientation different from a crystal orientation of the substrate, and the periodic structure It is the linker.

The periodic structure is formed by irradiating laser light onto a surface of the substrate by a laser concentrating means, and the laser concentrating means is preferably configured to: the inside of the substrate The light is collected in an axisymmetric manner with respect to the optical axis, and the light incident on the outer periphery of the laser light collecting means is closer to the laser light collected than the light incident on the inner peripheral portion of the laser light collecting means. The means side gathers light.

The periodic structure is preferably formed by moving the laser light collecting means to the substrate and irradiating the substrate with laser light by the laser light collecting means.

The foregoing periodic structure is in the aforementioned substrate by It is preferable that the light collecting point of the aforementioned laser light is phase-changed.

The modified layer is preferably formed to have a predetermined thickness and formed from a surface of the single crystal substrate at a predetermined depth.

The modified layer is preferably formed in parallel with the surface of the substrate.

It is preferable that the modified layer is formed in plural in parallel with the surface of the substrate.

The surface of the aforementioned substrate is preferably a mirror surface.

The substrate is preferably a tantalum single crystal substrate or a silicon carbide single crystal substrate.

A substrate processing method according to the present invention includes: a step of providing a single crystal substrate; and irradiating the laser light to a surface of the substrate by laser light collecting means, and forming a crystal orientation different from the substrate inside the substrate The step of modifying the layer of the periodic structure of the crystal orientation; wherein the laser light collecting means is configured to collect the laser light in an axisymmetric manner with respect to the optical axis while being incident inside the substrate The light that is outside the laser light collecting means is concentrated on the side closer to the laser light collecting means than the light that is incident on the inner peripheral portion of the laser light collecting means.

Preferably, the step of moving the aforementioned laser light collecting means relative to the substrate is preferably performed.

The periodic structure is preferably formed by phase-changing the light collecting point of the laser light in the substrate.

The aforementioned modified layer has a predetermined thickness and is composed of Preferably, the surface of the single crystal substrate is formed to have a predetermined depth.

The modified layer is preferably formed in parallel with the surface of the substrate.

It is preferable that the modified layer is formed in plural in parallel with the surface of the substrate.

The surface of the aforementioned substrate is preferably a mirror surface.

The substrate is preferably a tantalum single crystal substrate or a tantalum carbide single crystal substrate.

It is preferable that the substrate is cut by peeling off the modified layer.

10‧‧‧Substrate

14‧‧‧Internal reforming layer

20, 21‧‧‧Metal plates

25‧‧‧Binder

50‧‧‧cutting device

52‧‧‧ 台台

54‧‧‧cutting fixture

100‧‧‧In-substrate processing equipment

110‧‧‧ platform

120‧‧‧ Platform support

150‧‧‧Laser light source

160‧‧‧Laser Light Collection Department

170‧‧‧ objective lens

180‧‧‧ Plano-convex lens

190‧‧‧Laser light

Fig. 1 is a perspective view showing a processing apparatus inside a substrate.

Fig. 2 is a plan view showing a stage on which a substrate is placed.

Fig. 3 is a cross-sectional view showing a stage on which a substrate is placed.

Figure 4 is a diagram illustrating the irradiation of laser light onto a substrate.

Fig. 5 is a view showing a first embodiment in which a laser beam is irradiated onto a substrate.

Fig. 6 is a view showing a second embodiment in which laser light is irradiated onto a substrate.

Fig. 7 (a) and (b) are diagrams showing the aberration of the substrate.

Fig. 8 is a view showing a third embodiment in which a laser beam is irradiated onto a substrate.

Figure 9 is a view showing a fourth embodiment of irradiating a substrate with laser light. Figure.

Figure 10 is a front elevational view showing the cutting device.

Figure 11 is a view showing the peeling of the substrate from the metal plate in water.

Fig. 12 is a view showing a specific example of the laser light collecting portion.

Fig. 13 is a view showing another specific example of the laser light collecting portion.

Fig. 14 is a view showing a cross section of the internal reforming layer of Example 1.

Fig. 15 is a view showing a section of the cross section on the surface side of Example 2.

Figure 16 is a view showing a section of the back side of the embodiment 2

Fig. 17 is a view showing a section of the cross section on the surface side of Example 3.

Fig. 18 is a view showing a cross section of the back side of Example 3.

Fig. 19 is a view showing a section of the cross section on the surface side of Example 4.

Fig. 20 is a view showing a section of the cross section on the back side of Example 4.

Fig. 21 is a view showing a section of the cross section on the surface side of Comparative Example 1.

Fig. 22 is a view showing a cross section of the back side of Comparative Example 1.

Fig. 23 is a view showing a photograph of a cross section on the surface side of Comparative Example 2.

Fig. 24 is a view showing a cross section of the back side of Comparative Example 2.

In the following, the embodiments of the present invention will be described with reference to the drawings, in which the same or similar symbols are attached to the same or similar parts. However, the drawing is a schematic view, and the relationship between the thickness and the plane size, the thickness ratio of each layer, and the like are different from the actual one, and this point needs attention. Therefore, the specific thickness or size is determined by considering the following description. In addition, it is of course also included in the sections in which the dimensional relationships or ratios of the patterns are different from each other. Minute.

In addition, in the embodiment shown below, an apparatus or method for embodying the technical idea of the invention is exemplified. In the embodiment of the invention, the material, shape, configuration, arrangement, and the like of the structural member are not limited to the following. By. In the embodiment of the invention, various modifications can be added to the scope of the invention.

(Configuration of the internal processing device of the substrate)

Fig. 1 is a perspective view showing the configuration of the substrate internal processing apparatus 100. The substrate internal processing apparatus 100 includes a stage 110, a platform support portion 120 supported to move the stage 110 in the XY direction, and a substrate fixing tool 130 disposed on the stage 110 to fix the substrate 10.

Further, the substrate internal processing apparatus 100 includes a laser light source 150 and a laser light collecting unit 160 that collects the laser light 190 emitted from the laser light source 150 and irradiates the substrate 10 with light. The laser light collecting unit 160 has an objective lens 170 and a plano-convex lens 180.

2 is a plan view showing the substrate 10 placed on the stage 110. Figure 3 is a cross-sectional view showing the substrate 10 placed on the platform 110.

The substrate 10 is supported on the stage 110 by a substrate holding tool 130. The substrate fixing tool 130 is fixed to the substrate 10 by a fixed table 125 provided thereon. The fixed table 125 can be applied to a usual adhesive layer, a mechanical chuck, an electrostatic chuck, or the like.

A set of laser light 190 that collects and illuminates the substrate 10 The light spot P is formed inside the substrate 10, and a track 12 of a predetermined shape is formed by the surface in a predetermined depth region, whereby the two-dimensional internal reforming layer 14 can be formed in the horizontal direction of the surface.

Fig. 4 is a view for explaining the formation of the internal reforming layer 14 in the substrate 10. In the substrate internal processing apparatus 100, the laser light 190 is irradiated onto the substrate 10 via the objective lens 170 and the plano-convex lens 180 of the laser light collecting unit 160, and collects light inside the substrate 10.

In the present embodiment, the laser light collecting unit 160 is configured such that the outgoing laser light 190 of the laser light collecting unit 160 is axially symmetrical with respect to the optical axis thereof, and the outer periphery of the laser light 190 is inside the substrate 10. The light collecting point P2 at which the light rays of the side component 190b intersect is closer to the laser light collecting portion 160 than the light collecting point P1 where the light of the inner peripheral side 190a of the laser light 190 intersects.

In other words, since the surface of the substrate 10 faces the surface of the laser light collecting portion 160, the light collecting point P2 of the outer peripheral side component 190b of the laser light 190 is closer to the objective lens than the light collecting point P1 of the inner peripheral side 190a of the laser light 190. 170 and the plano-convex lens 180 side, that is, the shallow position from the surface of the substrate 10.

Such a state can be regarded as a state in which the aberration caused by the laser light 190 of the substrate 10 is excessively corrected, and can be referred to as a "defocusing" state of the so-called overcorrecting focus. With such a state, the diameter of the laser light can be substantially defined in a certain depth range of the substrate 10, and a sufficient energy density for forming the internal reforming layer 14 in this region can be ensured. In the figure, the internal reforming layer 14 is formed in a certain depth range t.

Internal reforming layer 14, with multiple crystals of polycrystalline germanium In the granules, the polycrystalline granules of the polycrystalline ruthenium are formed by concentrating the laser light 190 on the substrate 10, melting the crystallization of the single crystal, cooling, and changing the bonding state.

The internal reforming layer 14 thus formed has a periodic structure by irradiating the laser light 190 at periodic intervals, and the periodic structure has a polycrystal having a crystal orientation different from that of the single crystal. Needless to say, the polycrystals and the single crystals of different crystal orientations are all formed by the same element.

The internal reforming layer 14 is preferably exposed at the end of the substrate 10 in order to improve the production of the cutting step described later. The method of exposing the internal reforming layer 14 may be by cleavage of the crystal orientation or by using the laser light 190.

An embodiment in which the substrate 10 is irradiated with the laser light 190 by using the laser light collecting unit 160 will be described. Fig. 5 is a view showing the first embodiment. In Fig. 5, in a simple and convenient manner, the laser light collecting unit 160 is represented by a plano-convex lens 180, and the optical axis is described in the lateral direction. The collected light of the laser light is provided by the laser light collecting unit 160 including the plano-convex lens 180. And proceed.

In the first embodiment, the laser light 190 collected by the laser light collecting unit 160 is irradiated onto the surface of the substrate 10. The laser light 190 is refracted by the substrate 10, and the peripheral side component from the upper side of the optical axis is shallower than the inner peripheral side component at the lower position from the optical axis. Collecting light. In other words, the light on the outer peripheral side is collected at a position closer to the laser light collecting portion 190 than the light on the inner peripheral side.

Further, the position of the laser light collecting portion 160 with respect to the substrate 10 can be moved by a light collecting adjusting portion (not shown). The light collecting adjustment unit adjusts the light collecting position, the collecting shape, and the like of the laser light 190 in the substrate 10 by adjusting the distance between the laser light collecting unit 160 and the substrate 10 as will be described later. Such a light collecting adjustment unit can be easily realized by using a conventional technique.

Fig. 6 is a view for explaining a second embodiment in which a laser beam is irradiated onto a substrate. In the second embodiment, the distance between the laser concentrating portion 160 and the substrate 10 is larger than that of the first embodiment, and the laser light 190 collected by the laser concentrating portion 160 is the surface of the substrate 10. It is adjusted as a focus by the light collecting adjustment unit.

In the second embodiment, for example, as shown in the first embodiment, the position of the laser light collecting portion 190 with respect to the substrate 10 can be used in the initial setting before the light collecting point is set inside the substrate 10. In other words, in the second embodiment, the laser light 190 is disposed in the initial state in which the surface of the substrate 10 is the focus, and the surface distance between the laser light collecting portion 190 and the substrate 10 is set by the light collecting adjusting portion (not shown). By shortening to a predetermined value, as in the first embodiment, a desired light collecting point can be formed inside the substrate 10. Moreover, the initial setting is not limited to the surface of the substrate 10, and the focus can be focused on the back surface of the substrate 10.

Fig. 7 is a reference diagram illustrating aberrations in the substrate. This reference figure shows an aberration generated when the laser concentrating unit 160 is not provided in comparison with the first embodiment. For example, it is equivalent to the case where only a normal objective lens is provided.

In Fig. 7(a), as in the second embodiment, the base is The surface of the panel 10 is focused as a focus to concentrate the laser light 190. In this state, the substrate 10 is moved along the optical axis to the incident direction to cause the laser light 190 to collect light within the substrate 10. In this case, as shown in Fig. 7(b), the component on the outer peripheral side of the light having a high height from the optical axis is deeper than the surface on the inner peripheral side of the substrate 10 from the height of the optical axis. Collecting light.

In this state, the first embodiment in which the outer peripheral side component having a high height from the optical axis is collected at a shallower position than the inner peripheral component having a lower height from the optical axis is the height of the light and the light collected in the substrate 10. The depth of the point becomes the opposite relationship. In other words, the first embodiment in which the components on the outer peripheral side are collected at a shallower position than the components on the inner peripheral side is first realized by providing the laser concentrating portion 160.

Fig. 8 is a view showing a third embodiment in which laser light is irradiated onto a substrate. In the third embodiment, the light collecting point adjusting unit (not shown) is adjusted so as to shorten the distance between the laser light collecting unit 160 and the surface of the substrate 10, so that laser light is formed in the vicinity of the back surface of the substrate 10 in the substrate 10. Adjusted by the way of 190 light collection point. By this light collecting point, the internal reforming layer 14 on the surface of the parallel substrate 10 is formed in the vicinity of the back surface of the substrate 10.

Fig. 9 is a view showing a fourth embodiment in which laser light is irradiated onto a substrate. In the fourth embodiment, after the internal reforming layer 14a is formed in the vicinity of the back surface of the substrate 10 in the third embodiment, the distance between the laser concentrating portion 160 and the surface of the substrate 10 is enlarged by the concentrating point adjusting means (not shown). The method is adjusted to form a light collecting point of the laser light 190 in the vicinity of the surface of the substrate 10 in the substrate 10. By the light collecting point, the second internal reforming layer 14b on the surface of the parallel substrate 10 is formed in the vicinity of the surface of the substrate 10. Also, internal reform The layer 14 is not limited to two layers as in the fourth embodiment, and may have two or more layers.

(cutting of the substrate)

Figure 10 is a front elevational view showing the cutting device. According to the third or fourth embodiment, the substrate 10 having the internal reforming layer 14 is formed, and the internal reforming layer 14 is cut by the cutting device.

In the cutting device 50, a structure 40 is placed on the gantry 52. The structure 40 is a structure in which the first and second metal plates 20 and 21 are formed on both surfaces of the substrate 10 by using an adhesive. As the adhesive, it is sufficient that the adhesive is stronger than the cohesive force of the polycrystalline grains in the vicinity of the internal reforming layer 14 of the substrate 10. For example, hardening using metal ions as a reaction initiator can be used. An adhesive 25 made of a stimulating acrylic two-liquid monomer component.

The structure 40 can be fixed to the gantry 52 by a through hole provided in the second metal plate 21. In this state, a downward pressing force is applied to the first metal plate 20 by the cutting jig 54. Thereby, the substrate 10 receives a force in the opposite direction to the upper and lower directions of the first and second metal plates 20, 21, and when the force exceeds a predetermined critical value, the substrate 10 is divided, and the structure 40 is separated into 2 up and down.

( peeling of the substrate)

Fig. 11 is a view for explaining a method of peeling off the substrate 10 from the metal plate 20 in water. In the warm water of 80 to 100 ° C stored in the water tank 60, the metal sheets 20 and 21 are immersed in the substrate 10 to which the adhesive 25 is attached. After a predetermined time, the adhesive 25 produces a predetermined inverse with the water. Accordingly, since the adhesive force is lost by the adhesive 25, the substrate 10 can be separated from the metal sheets 20, 21 by peeling the adhesive 25 from the substrate 10 in water.

The final divided substrate can be obtained by drying the substrate 10 from which the adhesive 25 is peeled off. Further, in the fourth embodiment, when a plurality of internal reforming layers 14a and 14b exist, a plurality of internal reforming layers can be divided by a plurality of cutting steps of the substrate 10.

(Specific example of laser light collecting unit)

Fig. 12 is a view showing a specific example of the laser light collecting unit. In this specific example, the laser light collecting unit 160 is realized by, for example, combining the objective lens 170 having a high NA and a long operating distance with the plano-convex lens 180 provided on the surface side of the substrate 10.

Specifically, regarding the internal processing of the substrate 10 made of a single crystal crucible having a thickness of 1 mm, a glass plano-convex lens 180 having a focal length of 15 mm can be placed at a position of 0.14 mm from the surface side of the substrate 10 (sigma optical machine: SLB) -10-15P), and combined with an objective lens 170 (sigma optomechanical: EPL-10) of NA = 0.3.

In the laser light collecting unit 160, the light collecting point adjusting unit (not shown) is configured as follows, and the shape of the light collecting point is adjusted by the distance between the plano-convex lens 80 and the surface of the substrate 10, and the objective lens is used. The distance from the surface of the substrate 10 is adjusted to adjust the position of the light collecting point.

Fig. 13 is a view showing another specific example of the laser light collecting portion. Other specific examples are realized by an infrared objective lens having a correction ring of NA = 0.5 to 0.9. Specifically, for example, in the case of using Olympus lens LCPLN 100XIR, the inner processing layer 14 is set in the slave When the surface of the crystal 10 is at a position of 300 μm, the correction ring is set to 0.6 mm, and in the substrate 10, the light incident on the outer peripheral portion of the laser light collecting portion 160 can be made more light than the light incident on the inner peripheral portion. It is set close to the way of collecting light on the side of the laser collecting light 160.

According to the other embodiments, the plurality of constituent members of the objective lens 170 and the plano-convex lens 180 of the foregoing embodiment are not required, and since the single objective lens with the correction ring can be constructed, the configuration of the device becomes simple and the operation becomes variable. easily.

Further, in the other specific example, in the case where the internal reforming layer 14 is formed on the more surface side of the substrate 10, it is necessary to make the distance between the laser light collecting means 160 and the surface of the substrate 10 large. In this case, in order to suppress the influence of the laser light 190 on the surface of the substrate 10, a beam diameter adjusting means such as an iris diaphragm or a beam expander is disposed on the incident side of the laser light collecting portion 160 to reduce the outer peripheral side component of the laser light 190. The amount of light.

Example [Example 1]

In the first embodiment, the laser light source 150 as the substrate internal processing apparatus 100 uses a wavelength of 1064 nm, a repetition frequency of 200 kHz, an output of 1.6 W, and a pulse width of 10 nm. In the substrate internal processing apparatus 100, on the xy stage 110, which can be moved at a maximum speed of 200 mm/s in the x-axis and y-axis directions, a single crystal cymbal of a size of 50 x 50 mm and a thickness of 0.7 mm is mounted and mirror-finished. The substrate 10 is formed.

The laser light collecting unit 160 is an objective lens 200 (LCPLN 100XIR manufactured by Olympus) with a correction ring 210 of NA=0.85. then, After the correction ring 210 is set to 0 mm, it is observed by the reference beam, and the position of the objective lens 200 with respect to the surface of the substrate 10 is determined by forming a focus on the surface of the substrate 10 by the light irradiated by the objective lens 200. At this time, the distance between the objective lens 200 and the substrate 10 is 0.6 mm.

Next, with reference to this position, the objective lens 200 was moved to the surface of the substrate 10 by 0.06 mm. In this state, the setting of the correction ring 210 is regarded as 0.6 mm, the stage 110 is moved at a speed of 200 mm/s in the x direction, and 10 μm is transmitted in the y direction, and the repetition is performed 10 times, and the laser light 190 is applied from the objective lens 200 to the substrate 10. Ten linear lines were irradiated at intervals of 10 μm.

The substrate 10 was split at a right angle in a linear irradiation direction, and the cross section was observed. As a result, as shown in Fig. 14, it was confirmed that the length of the processed region was 30 μm at a depth of 0.3 mm from the mirror-side surface of the substrate 10, and the adjacent processing marks were connected to each other. The processing trace is a crystal structure in which a single crystal structure is transformed into a polycrystalline structure (phase change) by melting and cooling, which comprises a crystal orientation different from the crystal orientation of the single crystal, and constitutes a polycrystalline structure. The inner processing layer 14 of the periodic structure of the region connection.

[Embodiment 2]

As the laser light source 150, a fiber laser light A having a wavelength of 1064 nm is used, and a frequency of 200 kHz is repeated. An infrared objective lens having an opening number of 0.85 is used as the laser light collecting portion 160. The output power after the objective lens is 1.6 W, the pulse width is 39 ns, and the laser beam is irradiated. 1μm interval, offset 1μm, DF 80μm in air, 0.6mm to 矽 aberration correction ring, thickness 725μ The surface of the single crystal substrate 10 of the double-sided mirror processing (100) has a surface of 5 mm x 20 mm, and the laser light 190 is irradiated to form the internal reforming layer 14. Further, the surface of the substrate 10 refers to the main surface of the substrate 10 facing the laser light collecting portion 160, and the main surface of the substrate 10 opposite to the laser light collecting portion 160 is referred to as a back surface.

Then, on both surfaces of the front surface and the back surface of the substrate 10, the substrate 14 is divided by the cutting device 50 with the internal reforming layer 14 as a boundary line, and the exposed divided surface is a scanning electron microscope (made by Nippon Electronics Co., Ltd.). SEM) was observed. Fig. 15 is a view showing an image of a divided surface of the surface side enlarged by a scanning electron microscope. Fig. 16 is a view showing an enlarged surface of the divided surface on the back side by a scanning electron microscope.

[Example 3]

As the laser light source 150, a fiber laser beam B having a wavelength of 1064 nm is used, and the frequency is 200 kHz. The infrared objective lens having an opening number of 0.85 is used as the laser light collecting portion 160. The output power after the objective lens is 0.8 W, and the pulse width is 39 ns. Irradiation interval: 1 μm, offset by 1 μm, DF 80 μm in air, and irradiated with laser light to a surface of 5 mm x 20 mm of the surface of the single crystal substrate 10 mirror-processed (100) with a 矽 aberration correction ring of 0.6 mm and a thickness of 725 μm. The inner working layer 14 is formed 190.

In the same manner as in the second embodiment, the divided surface was observed after the substrate 10 was divided. Fig. 17 is a view showing a slice of the divided surface on the surface side by a scanning electron microscope. Fig. 18 is a view showing an enlarged image of the divided surface on the back side by a scanning electron microscope.

[Example 4]

As the laser light source 150, a fiber laser beam B having a wavelength of 1064 nm is used, and the frequency is 200 kHz. The infrared objective lens having an opening number of 0.85 is used as the laser light collecting portion 160. The output power after the objective lens is 0.8 W, and the pulse width is 39 ns. The irradiation interval was 1 μm, the offset was 2 μm, and the DF was 80 μm in air, and the laser light was irradiated to a surface of 5 mm x 20 mm of the surface of the single crystal substrate 10 which was mirror-processed (100) on both sides of the 矽 aberration correction ring of 0.6 mm and a thickness of 725 μm. The inner working layer 14 is formed 190.

In the same manner as in the second embodiment, the substrate 10 was divided and the divided surface was observed. Fig. 19 is a view showing an image of a divided surface of the surface side enlarged by a scanning electron microscope. Fig. 20 is a view showing an enlarged image of a divided surface on the back side by a scanning electron microscope.

[Comparative Example 1]

As the laser light source 150, a fiber laser light A having a wavelength of 1064 nm is used, and the frequency is 200 kHz. The infrared objective lens having an opening number of 0.85 is used as the laser light collecting portion 160, and the output power after the objective lens is 1.2 W, and the pulse width is 39 ns. The irradiation interval was 1 μm, the offset was 1 μm, and the DF was 80 μm in air, and the laser light 190 was irradiated to the surface of the 矽 single crystal substrate 10 having a mirror-correction ring of 0.6 mm and a thickness of 725 μm (100) on a surface of 5 mm x 10 mm. The inner processing layer 14 is formed.

In the same manner as in the second embodiment, the substrate 10 was divided and the divided surface was observed. Fig. 21 is a view showing an enlarged face of the surface on the surface side by a scanning electron microscope. Fig. 22 is a view showing an enlarged surface of the divided surface on the back side by a scanning electron microscope.

[Comparative Example 2]

As the laser light source 150, the optical laser light B having a wavelength of 1064 nm is used, and the repetition frequency is 200 kHz. The infrared objective lens having an opening number of 0.85 is used as the laser light collecting portion 160, and the output power after the objective lens is 0.6 W, and the pulse width is 60 ns. The irradiation interval was 1 μm, the offset was 1 μm, and the DF was 80 μm in air, and the laser light was irradiated to the surface of the single crystal substrate 10 of the mirror surface of the 矽 aberration correction ring of 0.6 mm and the thickness of 725 μm (100) on a surface of 5 mm x 10 mm. The inner working layer 14 is formed 190.

In the same manner as in the second embodiment, the divided surface was observed after the substrate 10 was divided. Fig. 23 is a view showing an image of a divided surface of the surface side enlarged by a scanning electron microscope. Fig. 24 is a view showing an enlarged image of the divided surface on the back side by a scanning electron microscope.

From the above Examples 1 to 4, Comparative Examples 1 to 2, in Examples 2 to 4, as in Example 1, the processing marks of the periodic structure were formed in the inner working layer 14, and the length of the processed region was as short as 30 μm. Adjacent processing marks are connected to form. In the second to fourth embodiments, since the internal reforming layer 14 having the processing marks formed by such joining is cut, a smooth cross section having a periodic structure can be obtained. Therefore, without further grinding, the man-hours required for other steps such as wet etching of chemical etching or laser etching and the effects of impurity contamination accompanying this step can be reduced.

As described above, the length of the processing region as in the first to fourth embodiments is short, and the inner processing layer 14 formed by joining adjacent processing marks can be formed by using the laser light collecting portion 160 configured as follows. Inside the substrate 10, the light collecting point of the outer peripheral side component of the laser light 190 is closer to the laser light collecting portion 160 than the light collecting point of the inner peripheral side component.

In Comparative Examples 1 to 2, since the adjacent processing marks in the internal reforming layer 14 were not connected, the cross section had a coarse particle size. Therefore, this section requires a step of grinding.

Further, in the above-described embodiment, a single crystal substrate is exemplified, but the same can be applied to, for example, tantalum carbide (SiC).

[Industrial availability]

According to the substrate processing apparatus and method of the present invention, a substrate which is thin and efficiently cut can be formed, and if it is a Si substrate, it can be applied to a solar cell, and a sapphire such as a GaN-based semiconductor device can be used. A substrate or the like may be used in a light-emitting diode or a laser diode. If it is SiC or the like, it may be applied to a SiC-based power device or the like, and may be suitable for a transparent electronic field, an illumination field, a hybrid/electric vehicle. In a wide range of fields such as fields.

Claims (18)

A substrate is a single crystal substrate, and the substrate has a modified layer therein, and the modified layer is formed with a periodic structure having a crystal orientation different from a crystal orientation of the substrate, and the periodic structure is connected to each other. The substrate according to claim 1, wherein the periodic structure is formed by irradiating laser light onto a surface of the substrate by a laser concentrating means, and the laser concentrating means is configured as follows. In the inside of the substrate, the laser light is collected in an axisymmetric manner with respect to the optical axis, and the light incident on the outer periphery of the laser light collecting means is incident on the inner peripheral portion of the laser light collecting means. Light collects light closer to the side of the aforementioned laser collecting means. The substrate according to claim 2, wherein the periodic structure moves the laser light collecting means relative to the substrate, and irradiates the laser light to the substrate by the laser light collecting means. . The substrate according to claim 1, wherein the periodic structure is formed by phase-changing a light collecting point of the laser light in the substrate. The substrate according to claim 1, wherein the modified layer has a predetermined thickness and is formed from a surface of the single crystal substrate at a predetermined depth. The substrate according to claim 1, wherein the modified layer is formed in parallel with a surface of the substrate. The substrate according to claim 1, wherein the foregoing modification The layer is formed in plurality in parallel with the surface of the substrate. The substrate of claim 1, wherein the surface of the substrate is a mirror surface. The substrate according to claim 1, wherein the substrate is a tantalum single crystal substrate or a tantalum carbide single crystal substrate. A substrate processing method comprising: providing a substrate of a single crystal; and irradiating laser light by a laser concentrating means on a surface of the substrate, wherein a crystal orientation different from a crystal orientation of the substrate is formed inside the substrate The step of modifying the layer of the periodic structure; wherein the laser light collecting means is configured to collect the laser light in an axisymmetric manner with respect to the optical axis, and to enter the foregoing in the inside of the substrate The light outside the laser collecting means is concentrated on the side closer to the laser collecting means than the light incident on the inner peripheral portion of the laser collecting means. The method of claim 10, wherein the method further comprises the step of moving the laser light collecting means relative to the substrate. The method according to claim 10, wherein the periodic structure is formed by phase-changing a light collecting point of the laser light in the substrate. The method of claim 10, wherein the modified layer has a predetermined thickness and is formed by the surface of the single crystal substrate at a predetermined depth. The method of claim 10, wherein the foregoing modification The layer is formed in parallel with the surface of the aforementioned substrate. The method of claim 10, wherein the modified layer is formed in parallel with a surface of the substrate. The method of claim 10, wherein the surface of the substrate is a mirror surface. The method of claim 10, wherein the substrate is a tantalum single crystal substrate or a tantalum carbide single crystal substrate. The method of claim 10, wherein the method is performed by peeling the substrate from the modified layer.