Separating device

Abstract

Separating device (1) for separating a composite substrate (6) into a first substrate (61) and a second substrate (62) which were previously bonded together, the separating device (1) comprising: a support base (2) having a support surface (211) for supporting the composite substrate (6) in a horizontal state; a side surface supporting means (3) provided on the supporting base (2) for supporting the peripheral side surface of the composite substrate (6) arranged on the supporting surface (211); and a separating means (4) for applying a separating force to the boundary (612) between the first substrate (61) and the second substrate (62) constituting the composite substrate (6) supported by the support surface (211) of the support base (2) and the side surface support means (3), thereby separating the composite substrate (6) into the first substrate (61) and the second substrate (62); the release agent (4) with a separating member (41) provided parallel to the bearing surface (211) of the bearing base (2) at a position opposite to the side surface bearing means (3), the separating member (41) having a wedge portion (412) adapted to be pressed into the boundary (612) between the first substrate (61) and the second substrate (62), a positioning means (42) for the separating element for moving the separating element (41) in a direction perpendicular to the bearing surface (211) of the bearing base (2) so as to position the wedge portion (412) at the level of the boundary (612) between the first substrate (61) and the second substrate (62), and a separator advancing and retracting means (43) for advancing and retracting the wedge portion (412) of the separator (41) with respect to the boundary (612) between the first substrate (61) and the second substrate (62) constituting the composite substrate (6) supported by the support surface (211) of the support base (2) and the side surface support means (3) wherein the side surface supporting means (3) comprises at least two rollers (31) for rotatably supporting the peripheral side surface of the composite substrate (6).

Description

TECHNICAL BACKGROUNDTechnical field

[0001] The present invention relates to a separating device for separating a composite substrate into a first substrate and a second substrate which were previously bonded together. State of the art

[0002] In a method for manufacturing an optical device, a light-emitting layer is formed via a buffer layer on a front surface of a substantially disc-shaped epitaxial substrate, such as a sapphire substrate and a silicon carbide substrate. The light-emitting layer consists of an n-type semiconductor layer and a p-type semiconductor layer of gallium nitride (GaN), indium gallium phosphide (InGaP), or aluminum gallium nitride (AlGaN). The light-emitting layer is separated into a plurality of regions by a plurality of intersecting streets, and a plurality of optical devices, such as light-emitting diodes or laser diodes, are respectively formed in the plurality of regions, thereby obtaining an optical device wafer. The optical device wafer is diced along the streets to produce the individual optical devices.

[0003] As a method for improving the luminance of an optical device, a manufacturing method called "lift-off" is described in JP-T-2005-516415. This method includes the steps of bonding a transfer substrate made of molybdenum (Mo), copper (Cu), silicon (Si) via a bonding metal layer made of gold-tin (AuSn), etc., to a light-emitting layer consisting of an n-type semiconductor layer and a p-type semiconductor layer, wherein the light-emitting layer is deposited via a buffer layer on the front surface of an epitaxial substrate made of sapphire, silicon carbide, etc.forming a wafer of optical devices, then applying a laser beam having an absorption wavelength (for example, 248 nm) to the buffer layer from the back side of the epitaxial substrate to thereby break the buffer layer, and then separating the epitaxial substrate from the light-emitting layer, whereby the light-emitting layer is transferred to the transfer substrate.

[0004] US 2004 / 0144487 A1 relates to a layer cutting device for separating a layer from a semiconductor substrate.

[0005] WO 2010 / 090147 A1 relates to a method for producing an electronic component.

[0006] JP S63- 316 450 A concerns the positioning of a reference on wafers of different sizes. PRESENTATION OF THE INVENTION

[0007] When a laser is applied from the back side of the epitaxial substrate in the state where the focal point of the laser beam is set on the buffer layer, gallium nitride (GaN), indium gallium phosphide (InGaP), or aluminum gallium nitride (AlGaN) constituting the buffer layer decomposes into gallium and gas (e.g., N2, etc.), thereby cracking the buffer layer. However, the thus-cracked buffer layer includes a region where gallium nitride (GaN), indium gallium phosphide (InGaP), or aluminum gallium nitride (AlGaN) has decomposed into gallium and gas (N2, etc.), and a region where the above-mentioned buffer layer material has not decomposed. Accordingly, the cracking of the buffer layer becomes non-uniform, resulting in a problem that the epitaxial substrate cannot be cleanly cut.

[0008] Furthermore, in the case where asperities are formed on the front surface of the epitaxial substrate so as to improve the luminance of each optical device, there is another problem that the laser beam may be interrupted by the limitation of the asperities and the breakage of the buffer layer may be suppressed accordingly, resulting in difficulty in separating the epitaxial substrate.

[0009] It is therefore an object of the present invention to provide a separating apparatus that can easily separate a composite substrate into a first substrate and a second substrate that were previously bonded together.

[0010] According to one aspect of the present invention, there is provided a separating device for separating a composite substrate into a first substrate and a second substrate that were previously bonded to each other, the separating device comprising: a support base having a support surface for supporting the composite substrate in a horizontal state, a side surface supporting means provided on the support base for supporting the peripheral side surface of the composite substrate that has been placed on the support surface, and a separating means for applying a separating force to the boundary between the first substrate and the second substrate that form the composite substrate supported on the support surface of the support base and the side surface supporting means, thereby separating the composite substrate into the first substrate and the second substrate, wherein the separating means comprises a separating member,which is provided parallel to the support surface of the support base at a position opposite to the side surface support means, wherein the separator has a wedge portion adapted to penetrate into the boundary between the first substrate and the second substrate, a separator positioning means for moving the separator in a direction perpendicular to the support surface of the support base so as to position the wedge portion at the level of the boundary between the first substrate and the second substrate, and a separator advancing and retracting means for advancing and retracting the wedge portion of the separator with respect to the boundary between the first substrate and the second substrate constituting the composite substrate supported by the support surface of the support base and the side surface support means.

[0011] Preferably, the side surface support means includes at least two rollers for rotatably supporting the peripheral side surface of the composite substrate. Preferably, the separating device further comprises a detecting means for detecting the boundary between the first substrate and the second substrate, which form the composite substrate supported by the support surface of the support base and the side surface support means, to align the wedge portion of the separating member with the boundary between the first substrate and the second substrate.

[0012] As described above, the separating apparatus according to the present invention comprises the support base having the support surface for supporting the composite substrate in a horizontal state, the side surface supporting means provided on the support base for supporting the peripheral side surface of the composite substrate disposed on the support surface, and the separating means for applying a separating force to the boundary between the first substrate and the second substrate constituting the composite substrate supported by the support surface of the support base and the side surface supporting means, thereby separating the composite substrate into the first substrate and the second substrate.The separating means includes the separator provided parallel to the support surface of the support base at a position opposite to the side surface supporting means, the separator having a wedge portion arranged to be pressed into the boundary between the first substrate and the second substrate. The separating means further includes the separator positioning means for moving the separator in a direction perpendicular to the support surface of the support base so as to position the wedge portion at the level of the boundary between the first substrate and the second substrate, and the separator advancing and retreating means for advancing and retreating the wedge portion of the separator with respect to the boundary between the first substrate and the second substrate constituting the composite substrate supported by the support surface of the support base and the side surface supporting means.Accordingly, when the wedge portion of the separator is moved into the boundary between the first substrate and the second substrate at multiple positions, a separating force can be applied to the boundary between the first substrate and the second substrate at multiple positions. By applying the present invention to a lift-off process of separating an epitaxial substrate from a light-emitting layer and then transferring the light-emitting layer to a transfer substrate, the epitaxial substrate can be easily and reliably separated even when the cracking of a buffer layer formed at the boundary between the epitaxial substrate and the light-emitting layer is uneven or when unevenness is formed on the front surface of the epitaxial substrate.

[0013] The above and other objects, features and advantages of the present invention and the manner of carrying it into effect will become more apparent and the invention itself will be best understood from a study of the following description and the appended claims with reference to the accompanying drawings which show a preferred embodiment of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a separating device according to a preferred embodiment of the present invention; Fig. 2 is an exploded perspective view of important components of the separator shown in Fig. 1 is shown; Fig. Fig. 3 is a cross-sectional view of an important part of the side surface bearing means forming part of the separating device shown in Fig. 1 is shown; Fig. 4 is a perspective view of a composite substrate formed by the Fig. 1 shown separating device is to be separated; and Fig. Fig. 5 is a perspective view illustrating a positioning step for the separating member performed using the separating device shown in Fig. 1 is to be carried out. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0014] A preferred embodiment of the separating device of the present invention will be described in detail with reference to the accompanying drawings. Fig. Fig. 1 is a perspective view of a separating device 1 according to a preferred embodiment of the present invention and Fig. 2 is an exploded perspective view of important components of the separating device 1 shown in Fig. 1 is shown.

[0015] The separating device 1 comprises a support base 2 for supporting a composite substrate which will be described below, a side surface supporting means 3 provided on the support base 2 for supporting the peripheral side surface of the composite substrate, and a separating means 4 for separating the composite substrate supported by the support base 2 and the side surface supporting means 3.

[0016] The support base 2 consists of a composite substrate support portion 21 and a release agent support portion 22 formed on the front side of the composite substrate support portion 21 so as to be lower in level than the composite substrate support portion 21. The composite substrate support portion 21 has a support surface 211 for supporting the composite substrate thereon in a horizontal state. Further, a clearance groove 212 for allowing the movement of a release member, which will be described later, is formed at a central portion of the front side (on the release agent support portion 22 side) of the composite substrate support portion 21.

[0017] The side surface bearing means 3 is provided on the bearing surface 211 of the bearing base 2. The side surface bearing means 3 consists of two rollers 31. As shown in Fig. 3, each roller 31 has an upper large-diameter portion 311 and a lower small-diameter portion 312. A central through-hole 313 extends axially through each roller 31. Each roller 31 is formed of a suitable synthetic resin. A bearing screw 32 is inserted through the through-hole 313 of each roller 31. An externally threaded portion 321 is formed at the front end portion (lower end portion) of the bearing screw 32. The externally threaded portion 321 of the bearing screw 32 engages with an internally threaded portion 213 formed in the bearing base 2. Accordingly, each roller 31 is rotatably supported on the bearing base 2 by the bearing screw 32.

[0018] With reference to Fig. 1 and Fig. 2, the separating means 4 includes a separating member 41 for separating the composite substrate supported by the support base 2 and the side surface supporting means 3, a separating member positioning means 42 for moving the separating member 41 in a direction perpendicular to the support surface 211 of the support base 2, and a separating member advancing and retracting means 43 for advancing and retracting the separating member 41 with respect to the composite substrate supported by the support base 2 and the side surface supporting means 3. The separating member 41 is composed of a bolt-like body portion 411 provided with an external screw thread 411a on the outer peripheral surface, a tapered spline portion 412 provided at one end of the body portion 411, and a rotatably actuated portion 413 provided at the other end of the body portion 411.

[0019] The separator positioning means 42 includes a guide member 421 provided on the separator support portion 22 of the support base 2, a movable block 422 provided to be vertically movable along the guide member 421, and a moving means 423 for vertically moving the movable block 422 along the guide member 421. The guide member 421 is provided with a T-shaped guide groove 421a extending vertically. The lower end portion of the guide member 421 is provided with two internally threaded holes (not shown) for engagement with two fastening screws described below. The separator support portion 22 of the support base 2 is provided with two mounting holes (through holes) 221, each corresponding to the aforementioned internally threaded holes of the guide member 421.Two mounting screws 44 are inserted through the two mounting holes 221 of the release agent support portion 22 from the lower side thereof in the state where the lower end surface of the guide member 421 on the release agent support portion 22 is arranged so that the two internally threaded holes of the guide member 421 are aligned with the two mounting holes 221. Further, the two mounting screws 44 are respectively engaged with the two internally threaded holes of the guide member 421, thereby mounting the guide member 421 on the release agent support portion 22. Although not shown, the lower surface (back side) of the release agent support portion 22 is provided with two recesses, each corresponding to the two mounting holes 221, for receiving the heads of the two fastening screws 44.

[0020] The movable block 422 has a T-shaped structure consisting of a supported portion 422a slidably engaged with the guide groove 421a of the guide member 421, and a partition member support portion 422b protruding from a side surface of the supported portion 422a. The supported portion 422a is provided with an internally threaded hole (through hole) 422c extending vertically. The partition member support portion 422b is provided with an internally threaded hole (through hole) 422d extending horizontally and engaging with the external screw thread 411a of the body portion 411 of the partition member 41.

[0021] The moving means 423 consists of a bolt portion 423b having an external screw thread 423a on the outer peripheral surface for engaging with an internally threaded hole 422c of the supported portion 422a of the movable block 422, a supported portion 423c provided at one end (lower end) of the bolt portion 423b, and a rotatably operated portion 423d provided at the other end (upper end) of the bolt portion 423b. The bolt portion 423b having the external screw thread 423a engages with an internally threaded hole 422c of the supported portion 422a of the movable block 422. In this state, the movable block 422 is slidably engaged with the guide groove 421a of the guide member 421, and the supported portion 423c of the moving means 423 is inserted through a support hole (through hole) 222 (see Fig. 2) formed in the separating means support portion 22 of the support base 2. Further, the lower end of the supported portion 423c is engaged with a bearing means 45 provided on the separating means support portion 22, so that the moving means 423 is rotatably supported on the separating means support portion 22 by the bearing means 45. Accordingly, when the rotatably operated portion 423d of the moving means 423 is held by a user to rotate the bolt portion 423b in one direction, the movable block 422 can be moved upward along the guide groove 421a, whereas when the bolt portion 423b is rotated in the other direction, the movable block 422 can be moved downward along the guide groove 421a.Although not shown, the lower surface (back surface) of the separating portion 22 for the separating means is provided with a recess corresponding to the bearing hole 222 for receiving the bearing 45 by press fitting.

[0022] The external screw thread 411a of the body portion 411 of the separator 41 engages with an internally threaded hole 422d of the separator support portion 422b of the movable block 422. When the rotatably operated portion 413 is held by the user to rotate the body portion 411 in one direction, the tapered wedge portion 412 provided at one end of the body portion 411 can be advanced toward the side surface support means 3, whereas when the body portion 411 is rotated in the other direction, the tapered wedge portion 412 can be retracted away from the side surface support means 3.Accordingly, the external screw thread 411a formed on the outer peripheral surface of the body portion 411 of the partition member 41, the rotatably operated portion 413 provided at the other end of the body portion 411, and the internally threaded hole 422d formed in the partition member supporting portion 422b of the movable block 422 act as the partition member advancing and retreating means 43 for advancing and retreating the wedge portion 412 of the partition member 41 with respect to the composite substrate supported by the supporting surface 211 of the supporting base 2 and the side surface supporting means 3.

[0023] With reference to Fig. 1, the separating device 1 further includes a detection means 5 for detecting the boundary between a first substrate and a second substrate constituting the composite substrate supported by the support surface 211 of the support base 2 and the side surface support means 3, to align the wedge portion 412 of the separating member 41 with this boundary. The detection means 5 consists of an imaging means 51 for imaging the side surface of the composite substrate supported by the support surface 211 of the support base 2 and the side surface support means 3, and a display means 52 for displaying an image obtained by the imaging means 51. The imaging means 51 is attached to the separating member support portion 422b of the movable block 422 at the same vertical position as that of the wedge portion 412.On the display means 52, a thread 521 is displayed which indicates the vertical center position of the image obtained by the imaging means 51 and which corresponds to the wedge portion 412.

[0024] The operation of the separating device 1 configured as above will now be described. Fig. Fig. 4 is a perspective view of a composite substrate 6 to be separated by the separating device 1. The composite substrate 6 shown in Fig. 4, consists of an optical device wafer 61 and a transfer substrate 62. The optical device wafer 61 consists of an epitaxial substrate 611 (first substrate), such as a sapphire substrate or a silicon carbide substrate, a buffer layer 612 formed on the front surface (bottom surface) of the epitaxial substrate 611, and an optical device layer (not shown) formed on the front surface (bottom surface) of the buffer layer 612. The transfer substrate 62 (second substrate) is formed of molybdenum (Mo), copper (Cu), silicon (Si), etc. The transfer substrate 62 is connected via a bonding metal layer (not shown) made of gold tin (AuSn) to the front side (bottom surface) of the optical device layer formed on the epitaxial substrate 611 (first substrate) via the buffer layer 612 of the optical device wafer 61.The buffer layer 612 in the composite substrate 6 was broken by applying a laser beam having a wavelength (for example, 248 nm) absorbed by the buffer layer 612 to the back surface (top surface) of the epitaxial substrate 611.

[0025] When separating the composite substrate 6 into the epitaxial substrate 611 (first substrate) and the transfer substrate 62 (second substrate) including the optical device layer using the separating apparatus 1, the composite substrate 6 is placed on the support surface 211 of the support base 2 in the state where the transfer substrate 62 (second substrate) is in contact with the support surface 211. Further, as shown in Fig. 5, the peripheral side surface of the composite substrate 6 is brought into abutment against the two rollers 31 constituting the side surface support means 3. Accordingly, the composite substrate 6 is rotatably supported by the two rollers 31 by the abutment of the peripheral side surface of the composite substrate 6 against the two rollers 31.

[0026] In the state where the composite substrate 6 is supported by the support surface 211 of the support base 2 and the two rollers 31 constituting the side surface support means 3, the rotatably operated portion 423d of the moving means 423 constituting the separator positioning means 42 is rotated in one direction or the other direction to thereby move the movable block 422 upward or downward so that the front end of the wedge portion 412 of the separator 41 attached to the movable block 422 is positioned at the level of the buffer layer 612 as the boundary between the epitaxial substrate 611 (first substrate) and the transfer substrate 62 (second substrate) including the optical device layer, as shown in Fig. 5 (positioning step of the separator). When performing this positioning step of the separator, the detection means 5 is actuated to image the peripheral side surface of the composite substrate 6 by the imaging means 51 and to display the image of the peripheral side surface of the composite substrate 6 by the display means 52. By aligning the buffer layer 612 with the thread 521 on the display means 52 (see Fig. 1) the front end of the wedge portion 412 of the separator 41 can be easily positioned at the level of the buffer layer 612 as a boundary between the epitaxial substrate 611 (first substrate) and the transfer substrate 62 (second substrate) including the optical device layer.

[0027] Subsequently, the rotatably operated portion 413 of the separator 41 is rotated in one direction to thereby advance the separator 41 toward the composite substrate 6, so that the front end of the wedge portion 412 penetrates by 1 to 2 mm into the buffer layer 612 as the boundary between the epitaxial substrate 611 (first substrate) and the transfer substrate 62 (second substrate) including the optical device layer (wedge advancing step).

[0028] After performing the wedge advancing step, the rotatably operated portion 413 of the separator 41 is rotated in the opposite direction to retract the separator 41 so that the wedge portion 412 is pulled out from the buffer layer 612 as the boundary between the epitaxial substrate 611 (first substrate) and the transfer substrate 62 (second substrate) including the optical device layer (wedge retraction step). After performing the wedge retraction step, the composite substrate 6 is rotated by a predetermined angle (for example, 30°) in contact with the two rollers 31 (composite substrate positioning step).

[0029] Subsequently, the wedge advancing step, the wedge retracting step, and the composite substrate positioning step are performed in this order, thereby exerting a separation force from the wedge portion 412 at multiple positions on the boundary between the epitaxial substrate 611 (first substrate) and the transfer substrate 62 (second substrate) including the optical device layer. Accordingly, the epitaxial substrate 611 (first substrate) can be easily separated from the transfer substrate 62 (second substrate). Accordingly, the optical device layer formed on the front surface of the epitaxial substrate 611 (first substrate) via the buffer layer 612 is transferred to the transfer substrate 62 (second substrate).

[0030] While a specific preferred embodiment of the present invention has been described with reference to the drawings, the present invention is not limited to the above preferred embodiment, and various modifications can be made within the scope of the present invention. For example, in the above preferred embodiment, the rotary-operated portion 423d of the moving means 423 constituting the separating member positioning means 42 and the rotary-operated portion 413 of the separating member 41 are manually operated, but stepper motors may also be attached to the rotary-operated portion 423d and the rotary-operated portion 413. Further, a jig for holding the composite substrate 6 under suction on the support surface 211 of the support base 2 may be provided. In such a case, the composite substrate 6 can be automatically separated into the first and second substrates.

Claims

[1] Separating device (1) for separating a composite substrate (6) into a first substrate (61) and a second substrate (62) which were previously bonded together, the separating device (1) comprising: a support base (2) having a support surface (211) for supporting the composite substrate (6) in a horizontal state; a side surface supporting means (3) provided on the supporting base (2) for supporting the peripheral side surface of the composite substrate (6) arranged on the supporting surface (211); and a separating means (4) for applying a separating force to the boundary (612) between the first substrate (61) and the second substrate (62) constituting the composite substrate (6) supported by the support surface (211) of the support base (2) and the side surface support means (3), thereby separating the composite substrate (6) into the first substrate (61) and the second substrate (62); the release agent (4) with a separating member (41) provided parallel to the bearing surface (211) of the bearing base (2) at a position opposite to the side surface bearing means (3), the separating member (41) having a wedge portion (412) adapted to be pressed into the boundary (612) between the first substrate (61) and the second substrate (62), a positioning means (42) for the separating element for moving the separating element (41) in a direction perpendicular to the bearing surface (211) of the bearing base (2) so as to position the wedge portion (412) at the level of the boundary (612) between the first substrate (61) and the second substrate (62), and a separator advancing and retracting means (43) for advancing and retracting the wedge portion (412) of the separator (41) with respect to the boundary (612) between the first substrate (61) and the second substrate (62) constituting the composite substrate (6) supported by the support surface (211) of the support base (2) and the side surface support means (3) wherein the side surface supporting means (3) comprises at least two rollers (31) for rotatably supporting the peripheral side surface of the composite substrate (6). [2] The separating device (2) according to claim 1 or 2, further comprising detecting means (5) for detecting the boundary (612) between the first substrate (61) and the second substrate (62) constituting the composite substrate (6) supported by the supporting surface (211) of the supporting base (2) and the side surface supporting means (3) to align the wedge portion (412) of the separating member (41) with the boundary (612) between the first substrate (61) and the second substrate (62).

Images