JP2009245967A - MANUFACTURING METHOD OF ZnO-BASED SEMICONDUCTOR DEVICE AND ZnO-BASED SEMICONDUCTOR DEVICE - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a ZnO-based semiconductor device suitable for the excellent division of a ZnO-based semiconductor light emitting element for instance. <P>SOLUTION: The manufacturing method of the ZnO-based semiconductor device includes: a scribing step of forming a scribe groove on the -C surface of a ZnO-based semiconductor member which has a wrutzite structure and whose upper surface is a +C surface and lower surface is the -C surface; and a braking step of braking the ZnO-based semiconductor member by pressing a member for cleavage to a position above the scribe groove of the +C surface. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a ZnO-based semiconductor device and a ZnO-based semiconductor device, for example, a method for manufacturing a ZnO-based semiconductor device suitable for light emission and a ZnO-based semiconductor device.

  In general, a large number of light emitting elements are formed side by side in the substrate surface, and then divided into individual light emitting elements by, for example, scribing and breaking. As a normal element dividing method, a scribe groove is formed in a gap between each light emitting element on the side where the light emitting element is formed, and pressure cleavage is performed with a knife edge from the back side. For example, Patent Document 1 discloses such a dividing method for a gallium nitride based semiconductor light-emitting element formed on a sapphire substrate.

  In this method, the end face of each light emitting element can be defined by proceeding with cleavage from the bottom of the scribe groove formed between the light emitting elements. The problem that the light emitting element is damaged by the end surface crossing the light emitting layer of the light emitting element is prevented.

  Patent Document 2 discloses another element dividing method for a gallium nitride based semiconductor light emitting element on a sapphire substrate. In Patent Document 2, a split groove is formed by etching between each light emitting element on the side where the light emitting element is formed, and a scribe groove is formed on the back surface side to perform element division, and an end face on the side where the light emitting element is formed Is arranged in the split groove.

  For example, zinc oxide (ZnO) is expected as a highly efficient light-emitting material, and a light-emitting element using a ZnO-based semiconductor has been proposed. When forming a ZnO-based semiconductor light emitting element on a C-plane ZnO substrate having a wurtzite structure, it is desirable to form it on the + C plane (Zn plane) side rather than the −C plane (O plane) side. For example, due to the crystal characteristics of ZnO, the etching rate with an acid solution or the like is very high on the −C plane side, and it is difficult to form an element. ). Further, for example, as disclosed in Patent Document 3, when the growth surface is the + C plane, the concentration of p-type impurity N added to the ZnO crystal can be higher than when the growth surface is the −C plane. It is easy to form a good light emitting element.

Japanese Patent No. 2748354 Japanese Patent No. 2780618 JP 2002-326895 A

  According to the present inventors' research, when a ZnO-based semiconductor light emitting device is formed on the + C surface on the C-plane ZnO substrate, a scribe groove is formed on the light emitting device side and braking is performed from the back surface side. It was found that chipping of the light emitting element was severe, and cleavage did not proceed from the bottom of the scribe groove, but cleavage occurred across the light emitting layer, and the light emitting element was easily damaged.

  An object of the present invention is to provide a method for manufacturing a ZnO-based semiconductor device suitable for, for example, good division of a ZnO-based semiconductor light emitting element.

  Another object of the present invention is to provide a well-divided ZnO-based semiconductor device that can be obtained by such a method of manufacturing a ZnO-based semiconductor device.

  According to one aspect of the present invention, a scribing step of forming a scribe groove in the −C plane of a ZnO-based semiconductor member having a wurtzite structure, the upper surface is a + C plane and the lower surface is a −C plane, There is provided a method for manufacturing a ZnO-based semiconductor device, comprising a breaking step of pressing a cleavage member against a position above the scribe groove to break the ZnO-based semiconductor member.

  According to another aspect of the present invention, the semiconductor device is made of a ZnO-based semiconductor having a wurtzite structure, the upper surface is a + C plane, the lower surface is a -C plane, and a scribe groove is formed at the edge on the -C plane side. A first portion having an end face formed by breaking by load cleavage from the side, and a region of the first portion that is pulled inward from the edge of the + C surface; A first ZnO-based semiconductor layer having a second ZnO-based semiconductor layer formed above the first ZnO-based semiconductor layer and having a second conductivity type opposite to the first conductivity type. A ZnO-based semiconductor device having a portion is provided.

  When a scribe groove is formed on the -C face of a ZnO-based semiconductor member having a wurtzite structure and pressure cleaving is performed from the opposite + C face side, for example, a derivative crack is likely to be generated in the depth direction at the bottom of the scribe groove, and is divided. It is easy to control the position of the end face of the member so that it passes through the bottom of the scribe groove.

  First, a wurtzite structure zinc oxide (ZnO) crystal will be described.

  FIG. 1A shows the surface orientation of the wurtzite structure. There are crystal planes such as C plane (0001), A plane (11-20), and M plane (10-10). The A plane and the M plane are orthogonal to the C plane. A plane perpendicular to the C plane and the A plane (M plane) is the M plane (A plane).

  FIG. 1B shows an atomic arrangement in the c-axis <0001> direction of a wurtzite structure ZnO crystal. Black circles indicate Zn atoms, and white circles indicate O atoms. O atom planes in which O atoms are arranged (O plane) and Zn atom planes in which Zn atoms are arranged (Zn plane) are alternately laminated in the c-axis direction, and the C plane of the wurtzite structure ZnO crystal is the Zn plane. It is classified into + C plane and -C plane which is O plane. One end side in the c-axis direction is a + C plane, and the opposite side is a -C plane. The + C plane side that is the Zn plane is polarized positively by + δ, and the −C plane side that is the O plane is polarized negatively by −δ.

  FIG. 1C shows a schematic perspective view of a C-plane ZnO substrate. The C-plane ZnO substrate is a ZnO substrate in which the + C plane is exposed on one side and the -C plane is exposed on the back side.

  Next, a configuration example of a ZnO-based semiconductor substrate with a light-emitting diode (LED) operation layer (hereinafter sometimes simply referred to as a substrate with an operation layer) used in the ZnO-based semiconductor light-emitting element of the embodiment will be described. Note that the ZnO-based semiconductor includes at least Zn and O.

  FIG. 2 is a schematic cross-sectional view of a substrate with an operation layer. An n-type conductive C-plane ZnO single crystal substrate having a thickness of 400 μm is prepared as the support substrate 1. In the C-plane ZnO substrate 1, one surface 11 is a + C surface, and the back surface 10 is a -C surface.

  On the + C plane 11 of the C-plane ZnO substrate 1, from the C-plane ZnO substrate 1 side, a ZnO layer 2 having a thickness of 10 nm, an n-type MgZnO layer 3 having a thickness of 300 nm, and ZnO / MgZnO not added with impurities are thickened. 3 layers of 2.5 nm / 7 nm stacked multi-quantum well (MQW) structure light emitting layer 4 and p-type MgZnO layer 5 having a thickness of 100 nm to which p-type impurities are added are stacked to form a substrate with an operation layer. Produced.

  The buffer layer 2 is grown at a low temperature of, for example, 300 ° C., and the n-type MgZnO layer 3, the light emitting layer 4, and the p-type MgZnO layer 5 are grown at a high temperature of, for example, 600 ° C. to 850 ° C. Note that the buffer layer 2 and the n-type MgZnO layer 3 can obtain an n-type conductivity without doping with an n-type impurity such as Ga. N is used as the p-type impurity added to the p-type MgZnO layer 5. The substrate with an operation layer prepared this time was manufactured by a radical source molecular beam epitaxy (RS-MBE) apparatus capable of supplying oxygen radicals by a radio frequency (RF) plasma gun.

  The buffer layer 2 to the p-type MgZnO layer 5 are epitaxially grown on the + C plane 11 of the C-plane ZnO substrate 1 so that the growth plane polarity is the + C plane. The surface 12 of the p-type MgZnO layer 5 which is the uppermost surface of the substrate with an operation layer is a + C plane.

  There are various semiconductor stacked structures applicable to semiconductor elements such as light emitting elements, but the minimum required functional layers are two layers, a p-type layer and an n-type layer forming a pn junction. However, when used as a light-emitting element, a configuration in which a light-emitting layer is inserted between a p-type layer and an n-type layer is common. Here, as a typical example, a configuration in which a p-type layer and an n-type layer are joined via a light emitting layer is given. An MQW structure is given as an example of the light emitting layer.

  The laminated structure of the buffer layer 2, the n-type MgZnO layer 3, the light emitting layer 4, and the p-type MgZnO layer 5 will be collectively referred to as an LED operation layer 6. The LED operation layer 6 side (+ C surface side) of the substrate with the operation layer is referred to as the upper side or the front side, and the ZnO support substrate 1 side (−C surface side) is referred to as the lower side or the back side.

  By the way, the MgO crystal takes a cubic rock salt structure as a stable crystal structure. On the other hand, the ZnO crystal takes a wurtzite structure which is a hexagonal crystal structure. As a result of recent research, a mixed crystal of ZnO crystal and MgO crystal, that is, MgZnO crystal in which Zn in ZnO is substituted with Mg has a hexagonal structure stably up to about 18% Mg composition, and is quasi-equilibrium The knowledge that the hexagonal crystal structure can be maintained up to about 50% of the Mg composition in the state has been obtained.

That is, Mg _x Zn _{(1-x) 2} O can have a wurtzite structure when the Mg composition x is in the range of 0 ≦ x <0.5. In the prepared substrate with an operation layer, the Mg composition of MgZnO was selected so as to have a wurtzite structure (the Mg composition ratio of the p-type MgZnO layer and the n-type MgZnO layer was 0.2, the composition of the MgZnO layer of the light emitting layer) Ratio 0.15). In addition, the maximum processing temperature is 500 ° C. in the process (especially the RTA process in the alloying / transparent process of the electrode) from taking out the substrate with the operation layer from the film forming apparatus to forming individual elements as described later. Suppressed to below.

  Next, a method for manufacturing a ZnO-based semiconductor light emitting device according to the first embodiment of the present invention will be described. A large number of light-emitting elements having the same structure are simultaneously formed on the surface of the substrate with the operation layer as described above and separated into individual light-emitting elements.

  3A is a schematic top view of the light emitting device of the first embodiment, and FIG. 3B is a diagram of the light emitting device of the first embodiment along the one-dot chain line AA ′ in FIG. FIG. 3C is a schematic sectional view, and FIG. 3C is a schematic bottom view of the light emitting device of the first embodiment. Note that these drawings particularly show one light emitting element and its vicinity.

  The planar shape (die size) of each light emitting element is set to a square with a pair of sides parallel to the a-axis <11-20> and the other pair of sides parallel to the m-axis <10-10>. The length of one side is 400 μm, for example.

  First, a resist mask opened in the shape of the p-side electrode 20 is formed on the p-type MgZnO layer 5 by photolithography. The planar shape of the p-side electrode 20 is, for example, a square in which a pair of sides is parallel to the a-axis and the other pair of sides is parallel to the m-axis, and the length of one side is 270 μm, for example.

  The p-side electrode 20 is formed on the p-type MgZnO layer 5 by electron beam (EB) vapor deposition with a thickness of 0.3 nm to 10 nm and a thickness of 5 nm to 20 nm. Thereafter, the electrode material other than the mask opening is removed by a lift-off method.

  Note that a structure in which a plurality of materials (for example, Ni, Au) are stacked from the substrate side with the operating layer is arranged on the left side as the material on the substrate side with the operating layer is described as Ni / Au or the like.

  The formed p-side electrode 20 was heat-treated in a rapid thermal annealer (RTA) at 500 ° C. for 30 seconds in an oxygen atmosphere to perform alloying and oxidization and transparency of the Ni / Au layer.

  Next, a resist mask opened in the shape of the p-side electrode pad 21 is formed on the p-side electrode 20 by photolithography. The planar shape of the p-side electrode pad 21 is, for example, a circle having a diameter of 100 μm.

  Ni / Pt / Au is laminated with a thickness of 1 nm to 10 nm / 100 nm / 1000 nm by EB vapor deposition to form a p-side electrode pad 21 on the p-side electrode 20. Thereafter, the vapor deposition material other than the mask opening is removed by a lift-off method.

  Next, a resist mask that covers the p-side electrode pad 21 and the p-side electrode 20 and opens in the shape of the contour groove 30 is formed on the p-type MgZnO layer 5 by photolithography. The contour groove 30 is a square lattice-shaped groove along the outer shape of each light emitting element, and separates adjacent light emitting elements with respect to the thickness portion where the pn junction is disposed.

  The p-type MgZnO layer 5, the light emitting layer 4, the n-type MgZnO layer 3, and the buffer layer 2 in the opening are removed by wet etching, and the contour groove 30 has a depth that exposes the upper surface (+ C surface) of the ZnO substrate 1 on the bottom surface. Form. As the etchant, for example, a 10: 1 mixed solution of ethylenediaminetetraacetic acid disodium (EDTA) and ethylenediamine (EDA) can be used. Next, the resist mask is removed by washing. Note that reactive ion etching (RIE) can also be used as the etching for forming the contour groove 30.

  By forming the contour groove 30, the thickness portion from the upper surface of the p-type MgZnO layer 5 to the upper surface of the ZnO substrate 1 is left in a shape drawn inward from the set outer shape (a square having a side of 400 μm). The remaining operation layer portion is referred to as an LED operation layer portion 7.

  The planar shape of the LED operation layer portion 7 is, for example, a square in which a pair of sides is parallel to the a axis and the other pair of sides is parallel to the m axis, and the length of one side is, for example, 300 μm. The width of the contour groove 30 (the distance between the LED operation layer portions 7 of adjacent elements) is, for example, 100 μm.

  Next, the LED operation layer side of the substrate with the operation layer was attached to a protective substrate, which was set on a grinding machine, and the original 400 μm thick ZnO substrate 1 was ground to a thickness of 170 μm. Subsequently, the polishing material was gradually lowered (reduced the particle size) and polished to a thickness of about 150 μm until the ground surface became a mirror surface with a polishing apparatus.

  Next, a resist mask having an opening in the shape of the n-side electrode 22 is formed on the back surface of the ZnO substrate 1 as the operation layer-attached substrate by photolithography. The planar shape of the n-side electrode 22 is, for example, a square in which a pair of sides is parallel to the a-axis and the other pair of sides is parallel to the m-axis, and the length of one side is, for example, 270 μm.

  Ti / Au is laminated with a thickness of 10 nm to 100 nm / 300 nm to 1000 nm by EB vapor deposition to form an n-side electrode 22 on the back surface of the ZnO substrate 1. Thereafter, the vapor deposition material other than the mask opening is removed by a lift-off method.

  As shown in FIG. 3C, on the back side of the ZnO substrate 1, the -C plane of the ZnO substrate 1 is exposed between the n-side electrodes 22 of the adjacent light emitting elements. The exposed region 31 on the −C plane has a square lattice shape in which a region elongated in the a-axis direction and a region elongated in the m-axis direction intersect.

  The center line of the region elongated in the a-axis direction is the center line 32a, and the center line of the region elongated in the m-axis direction is the center line 32m. A square formed by the two adjacent center lines 32a and the two adjacent center lines 32m matches the set outer shape of each light emitting element.

  Next, a scribe groove extending in the a-axis direction along the center line 32a is formed in the exposed region 31 of the -C plane, and a scribe groove extending in the m-axis direction along the center line 32m is formed. Form.

  The center line of the elongated portion in the a-axis direction of the bottom of the square lattice shape of the contour groove 30 is the center line 34a, and the center line of the elongated portion in the m-axis direction is the center line 34m. The center line 34 at the bottom of the contour groove 30 is disposed vertically above the center line 32 of the exposed region 31 on the back side of the substrate 1, that is, vertically above the scribe groove.

  Next, the knife edge of the braking device is pressed against the + C plane which is the bottom of the contour groove 30 along the center line 34a, and is cleaved under pressure, thereby dividing the element in the m-axis direction and along the center line 34m. Then, the element is divided in the a-axis direction by pressing the knife edge and cleaving under pressure.

  In the scribing process, a scribe groove is formed so as to extend in the length direction of the bottom below the bottom of the contour groove, and in the breaking process, the knife edge is formed in the bottom direction of the bottom of the contour groove. Is pushing along.

  Due to the braking, ideally, a cleavage plane of the M plane including the center lines 32a and 34a extending in the a-axis direction, and a cleavage plane of the A plane including the center lines 32m and 34m extending in the m-axis direction, Are obtained, and these become the setting end faces of the respective light emitting elements.

  Next, the scribing and braking of the example will be further described, and the scribing and braking of the comparative example will be described. In the comparative example, as in the first embodiment, a p-side electrode, a p-side electrode pad, and a contour groove are formed on the LED operation layer side of the substrate with the operation layer, and the substrate is ground and polished. An n-side electrode is formed on the back surface of the substrate with a layer. Subsequent scribing and braking is different from the first embodiment.

  First, scribing and braking of a comparative example will be described.

  FIG. 7A is a schematic cross-sectional view for explaining a scribing process of a comparative example. In the comparative example, the scribe groove 133 is formed by moving the cutting edge of the scribe tool 140 along the center line 34 at the bottom of the contour groove 30 where the + C surface on the front side of the substrate 1 is exposed.

  There are several types of scribing tool points. The crystal structure of diamond is divided into a three-point tool with a cutting edge in three directions and a four-point tool with a cutting edge in four directions. Also, it can be divided into a toe point tool that uses the tip side as the cutting edge and a heel point tool that uses the back side.

  FIG. 8 is a micrograph obtained by observing the scribe groove of the comparative example from the + C plane normal direction, and a schematic cross-sectional view showing a cross-sectional shape of the scribe groove. As a scribing tool, a three-point toe point tool was used, and scribing was performed under conditions of a cutting edge angle of 70 ° and a cutting edge load of 100 g. The scribe groove 133 was severely chipped on both sides of the blade locus, and no derived crack was generated from the bottom of the scribe groove.

  FIG. 7B is a schematic cross-sectional view for explaining the braking process of the comparative example. The knife edge 141 is pressed along the center line 32 against the -C surface exposed region 31 on the back side of the substrate 1 to cleave the ZnO substrate 1 to separate the light emitting elements. As shown in FIG. 8, the brake is applied to a position off the scribe groove due to severe chipping on both sides of the blade locus and braking in a state where no derivative crack is generated from the bottom of the scribe groove. The breaking cutting surface 151 is likely to occur, the breaking cutting surface 151 crosses the LED operation layer portion 7, and the LED operation layer portion 7 is easily broken. In addition, suppose that the cross section formed by braking is called a breaking cut surface.

  In addition, even when using a 4-point heel point tool as a scribing tool and scribing under the condition of a cutting edge load of 50 g to 150 g, the tendency is substantially the same, and the LED operation layer portion 7 is easily destroyed.

  Next, scribing and braking according to the embodiment will be described. In the embodiment, contrary to the comparative example, a scribe groove is formed on the −C plane side, and a knife edge is applied to the + C plane side.

  FIG. 4A is a schematic cross-sectional view for explaining the scribing process of the embodiment. The cutting edge of the scribe tool 40 is moved along the center line 32 of the −C surface exposed region 31 on the back side of the substrate 1 to form the scribe groove 33. Derived cracks 50 are formed in the substrate thickness direction (depth direction) from the bottom of the scribe groove 33.

  FIG. 5 is a micrograph of the scribe groove of the example observed from the normal direction of the -C plane, and a schematic cross-sectional view showing the cross-sectional shape of the scribe groove. A 4-point heel point tool was used as the scribe tool, and scribing was performed under the conditions of a blade edge angle of 52 ° and a blade edge load of 100 g. In the scribe groove 33, chipping is suppressed on both sides of the cutting edge locus, and a derivative crack 50 is formed in the substrate thickness direction from the scribe groove bottom.

  The 4-point heel point tool requires a wide pressure contact surface, but can be used without any problem from the n-side electrode side on the back surface of the substrate. The heel point tool is suitable for scribing with reduced chipping.

  FIG. 4B is a schematic cross-sectional view for explaining the braking process of the embodiment. The knife edge 41 is pressed along the center line 34 at the bottom of the contour groove 30, and the ZnO substrate 1 is cleaved by load to separate the light emitting elements. As shown in FIG. 5, the chipping is suppressed on both sides of the blade locus, and braking is performed in a state where the derivative crack 50 is formed in the substrate thickness direction from the bottom of the scribe groove 33, thereby causing the derivative crack 50. The breaking cut surface 51 is likely to be formed along the upper edge of the contour groove 30, and the upper end of the braking cut surface 51 is likely to appear in the bottom of the contour groove 30. Thereby, each light emitting element is divided | segmented so that it may become a substantially external shape as set, and destruction of the LED operation | movement layer part 7 is prevented.

  As described above, the scribing and braking method of the embodiment performs scribing on the + C plane side by scribing on the −C plane side and braking on the + C plane side, and braking on the −C plane side. Compared to the method to be performed, the ZnO-based semiconductor element can be easily divided.

  Note that the scribe groove formation characteristics are the same on the front side (LED operation layer side) and back side (substrate side) of the substrate with the operation layer, and a derivative crack in the substrate thickness direction is also formed on the bottom of the scribe groove formed on the front side. If this is done, a braking cut surface passing through the derived crack is likely to be formed at the time of braking, and it will be easy to match the division position on the LED operation layer side with the position of the scribe groove. If it can do in this way, there will be no problem that a breaking cut surface is generated across the LED operation layer portion, so it is better to scribe on the front side and brake from the back side.

  GaN has a wurtzite structure like ZnO. For example, in an InGaN-based LED, a C-plane GaN substrate is used. In the C-plane GaN substrate, the scribe groove formation characteristics are the same on the + C plane side and the −C plane side, and the LED operation layer formation side can be scribed well and braking can be performed from the back side.

  However, when the LED operation layer is formed on the + C surface side of the C-plane ZnO substrate, as described above, when scribing is performed on the front side (LED operation layer side) and braking is performed from the back side (substrate side), the scribe groove Derived cracks are unlikely to be formed at the bottom, and there is a concern that the LED operating layer may be damaged when the breaking cut surface is detached from the scribe groove.

  The inventors of the present application, when scribing the −C plane of the C-plane ZnO substrate, forms a tight scribe groove with reduced chipping more easily than when scribing the + C plane, and further, a thick scribe groove is formed at the bottom of the scribe groove. It was found that derivative cracks are easily formed in the vertical direction. It was also found that cracks were likely to occur in the thickness direction (in the direction perpendicular to the surface) on the -C plane, whereas cracks were likely to occur in the in-plane direction (in a direction parallel to the surface) on the + C plane.

  Then, for the ZnO-based semiconductor element in which the LED operation layer is formed on the + C plane side of the C-plane ZnO substrate, a scribe groove is formed on the −C plane side, and a knife edge is applied to the + C plane side for braking. It has been found that good element division becomes easy. In addition, since the latent scratch due to the scribe stress remains in the vicinity of the substrate surface on the side opposite to the LED operation layer forming side, there is also an advantage that a defect that induces an operation failure of the LED operation layer hardly occurs.

  In general, a wurtzite crystal is easily cleaved on the M-plane and hardly cleaved on the A-plane. Therefore, when it is going to cleave along A surface, it becomes easy to become a braking cutting surface which deviated from A surface. Therefore, in general, a three-point to-point tool is used. The three-point tool has a strong stress that spreads the crystal and is likely to generate a crack from the scribe groove.

  However, the present inventors have found that a 4-point heel point tool is more suitable than a 3-point toe point tool when scribing the -C plane of a C-plane ZnO substrate.

  The 4-point heel point tool tends to cause point stress to be perpendicular to the surface. For example, by using this under the conditions of a cutting edge angle of 52 ° and a cutting edge load of 100 g, cracks can be easily introduced in the direction perpendicular to the −C plane. The 4-point heel point tool is also effective in suppressing chipping.

  The blade edge angle (tool setting angle) is not limited to 52 °, but is preferably in the range of 50 ° to 54 °. Since the ZnO crystal has a Mohs hardness of about 4, the chipping becomes noticeable when the cutting edge load at scribe is 150 g or more. For scribing on the -C surface, the blade load in the range of 80 to 120 g was optimal.

  Next, a preferable width of the contour groove will be described. As a result of the test, even when trying to obtain the cleaved surface of the A surface by the scribe groove extending in the m-axis direction, even when trying to obtain the cleaved surface of the M surface by the scribe groove extending in the a-axis direction, The inclination of the crack generated at the bottom of the scribe groove from the normal direction of the substrate was rarely 18 ° or more.

  Therefore, as shown in FIG. 3B, the contour groove is formed such that a surface 60 including the center line 32 on the back surface of the substrate 1 forming the scribe groove and inclined by 18 ° from the normal direction of the substrate intersects the bottom of the contour groove 30. If the width of 30 is set wide, the upper end of the breaking cut surface appears in the bottom of the contour groove 30, and the possibility that the breaking cut surface crosses the LED operation layer portion 7 can be reduced. By setting the width of the contour groove 30 in this way, the yield of the element dividing process is remarkably improved to 70% to 90%. This is effective even if the element shape is not square but is rectangular, for example. The yield when scribing from the + C plane side and braking from the -C plane side is about 20% to 30%.

  The thickness from the bottom of the contour groove 30 to which the knife edge is applied in the braking process to the scribe groove on the back surface of the substrate 1 is referred to as a breaking cutting thickness. In the first embodiment, the breaking cut thickness is 150 μm of the substrate 1 after grinding and polishing.

  Since tan 18 ° is about 0.325, when the breaking cut thickness is 150 μm, it is necessary to secure a width of 48.7 μm (150 μm × 0.325) or more from the center line 34 of the contour groove 30. The upper end of the breaking cut surface is stored in the bottom of the contour groove 30. In the first embodiment, with respect to the thickness of the substrate 1 at the time of braking of 150 μm, the width of the contour groove 30 is ensured by 50 μm on both sides from the center line 34 to 100 μm.

  By forming the contour groove, the LED operation layer between the LED operation layer portions of the adjacent light emitting elements is removed. Since the knife edge is applied to the bottom of the contour groove from which the LED operation layer is removed in the braking process, there is an advantage that the knife edge does not damage the light emitting layer. Note that the contour groove does not affect the cleavage property in the scribing and braking process.

  Next, a method for manufacturing a ZnO-based semiconductor light emitting device according to the second embodiment will be described. The second embodiment differs from the first embodiment in the depth of the contour groove 30. The difference from the first embodiment will be described below.

  6A is a schematic top view of the light emitting device of the second embodiment, and FIG. 6B is a diagram of the light emitting device of the second embodiment along the one-dot chain line AA ′ in FIG. It is a schematic sectional drawing.

  Similarly to the first embodiment, the p-side electrode 20 and the p-side electrode 21 are formed. Next, as in the first embodiment, a resist mask opened in the shape of the contour groove 30 is formed.

  Next, by RIE, the p-type MgZnO layer 5, the light emitting layer 4, and the n-type MgZnO layer 3 are partially removed from the opening of the resist mask, and the n-type MgZnO layer 3 is exposed to a depth at the bottom. A contour groove 30 is formed. Next, the resist mask is removed by washing.

  Next, in the same manner as in the first embodiment, the substrate 1 is ground and polished to form a thin film, the n-side electrode 22 is formed, and further, scribing and breaking are performed to separate each light emitting element.

  For example, the thickness of the substrate 1 after grinding / polishing is set to 150 μm as in the first embodiment. The thicknesses of the p-type MgZnO layer 5, the light-emitting layer 4, the n-type MgZnO layer 3, and the buffer layer 2 are, for example, 100 nm, 28.5 nm (2.5 nm / 7.5 nm stack × 3), 400 nm, and 10 nm, respectively. is there. When the depth of the contour groove 30 is, for example, 250 nm, the thickness from the bottom of the contour groove 30 to the upper surface of the substrate 1 is 288.5 nm, and the breaking cut thickness obtained by adding the thickness of the substrate 1 is about 150.3 nm. It becomes.

  Since tan18 ° is about 0.325, if the width of 48.8 μm (150.3 μm × 0.325) or more is secured across the center line 34 of the contour groove 30, the upper end of the braking cut surface In the bottom of the contour groove 30. Also in the second embodiment, for example, the width of the contour groove 30 may be set to 100 μm.

  By breaking, the ZnO substrate 1 is broken in the first embodiment, but the n-type MgZnO layer 3 is also broken in addition to the ZnO substrate 1 in the second embodiment. As a result of the experiment, the MgZnO crystal having the wurtzite structure has the same cleavage characteristics as the ZnO crystal, so that the light emitting device of the second embodiment can be divided in the same manner as the first embodiment.

  In addition, even ZnO-based semiconductor members in which Se, S, Cd, or the like other than Mg is introduced and the wurtzite structure is maintained will exhibit the same cleavage characteristics as ZnO crystals.

  In the second embodiment, since the n-type MgZnO layer 3 is left, in addition to the thickness of the substrate 1 after grinding and polishing, the thickness of the n-type MgZnO layer 3 remaining after etching and The thickness of the buffer layer 2 is included. The thickness of the substrate 1 can be adjusted by grinding and polishing, and the thickness of the n-type MgZnO layer 3 can be adjusted by etching when the contour groove 30 is formed.

  As described in the first embodiment, by ensuring the width of the contour groove 30 to be at least twice tan18 ° of the breaking cutting thickness, the upper end of the braking cut surface is likely to appear in the bottom of the contour groove 30. Thus, destruction of the LED operation layer portion is suppressed.

  Note that the thinner the breaking cutting thickness, the narrower the width of the contour groove 30 and the larger the number of elements obtained from the same size substrate. From this viewpoint, it can be said that the contour groove structure of the first embodiment is more effective. Note that a method of further reducing the breaking cutting thickness by forming a contour groove deeper than the upper surface of the substrate 1 is also conceivable.

  The n-type MgZnO layer 3 is grown on the C plane of the ZnO substrate 1, but when the growth plane polarity of the n-type MgZnO layer 3 becomes the -C plane, the n-type MgZnO layer 3 extends from the scribe groove on the back surface of the substrate 1 and n. The breaking cut surface reaching the interface with the type MgZnO layer 3 extends in the in-plane direction, and the LED operation layer portion 7 is peeled off. In order to prevent such a problem, it is important that the LED operation layer 6 is grown on the C plane of the ZnO substrate 1 so that the growth plane is the C plane.

  The characteristics of the divided light emitting elements of the first and second embodiments can be summarized as follows. The thickness portion from the back of the substrate 1 of the substrate with the operation layer to the bottom of the contour groove 30 is referred to as a first portion, and the LED operation layer portion 7 above it is referred to as a second portion.

  The first part is made of a ZnO-based semiconductor having a wurtzite structure, the upper surface is a + C plane, the lower surface is a -C plane, a scribe groove is formed at the edge on the -C plane side, and a brake by load cleavage from the + C plane side. An end surface is formed by being divided by the ring.

  The second portion is disposed on a region pulled inward from the edge of the + C plane of the first portion, and is located above the first ZnO-based semiconductor layer having the first conductivity type and the first ZnO-based semiconductor layer. And a second ZnO-based semiconductor layer having a second conductivity type opposite to the first conductivity type.

  Further, when a surface including a scribe groove and inclined by 18 ° from the normal direction of the −C surface that is the lower surface of the first portion is intersected with the + C surface that is the upper surface of the first portion. The position is arranged outside the second portion.

  In the above embodiments, the light emitting element is divided as an example. However, the dividing technique in which a scribe groove is formed on the −C plane side and the load is cleaved from the + C plane side has a wurtzite structure, and one is a + C plane. The other can be used to satisfactorily divide a ZnO-based semiconductor member having a -C plane.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

1A is a schematic perspective view showing the surface orientation of the wurtzite structure, and FIG. 1B is a schematic view showing the atomic arrangement in the c-axis direction of the ZnO crystal of the wurtzite structure. ) Is a schematic perspective view of a C-plane ZnO substrate. FIG. 2 is a schematic cross-sectional view of a substrate with an operation layer. FIGS. 3A to 3C are a schematic top view, a schematic cross-sectional view, and a schematic bottom view, respectively, of the light emitting device of the first example. FIG. 4A is a schematic cross-sectional view for explaining the scribing process of the embodiment, and FIG. 4B is a schematic cross-sectional view for explaining the braking process of the embodiment. FIG. 5: is a schematic sectional drawing which shows the microscope picture of the scribe groove | channel of an Example, and the cross-sectional shape of a scribe groove | channel. FIGS. 6A and 6B are a schematic top view and a schematic cross-sectional view, respectively, of the light emitting device of the second embodiment. FIG. 7A is a schematic cross-sectional view for explaining the scribing process of the comparative example, and FIG. 7B is a schematic cross-sectional view for explaining the braking process of the comparative example. FIG. 8 is a schematic cross-sectional view showing a micrograph of a scribe groove of a comparative example and a cross-sectional shape of the scribe groove.

Explanation of symbols

1 C-plane ZnO substrate 2 Buffer layer 3 n-type MgZnO layer 4 Light-emitting layer 5 p-type MgZnO layer 6 LED operation layer 7 LED operation layer portion 10 -C surface 11, 12 + C surface 20 p-side electrode 21 p-side electrode pad 22 n Side electrode 30 Contour groove 31 -C surface exposed region 32 (on exposed region 31) center line 32a (on exposed region 31) a-axis direction center line 32m (on exposed region 31) m-axis direction center line 33 Scribe groove 34 Center line 34a (bottom of contour groove 30) a-axis center line 34m (bottom of contour groove 30) m-axis center line 40 (bottom of contour groove 30) Scribe tool 41 Knife edge 50 Derived crack 51 Breaking cut surface

Claims (7)

A scribing step of forming a scribe groove in the −C plane of a ZnO-based semiconductor member having a wurtzite structure, the upper surface being a + C plane and the lower surface being a −C plane;
A manufacturing method of a ZnO-based semiconductor device, comprising: a breaking step of pressing a cleavage member against a position of the + C plane above the scribe groove to break the ZnO-based semiconductor member. The ZnO-based semiconductor member includes a C-plane ZnO-based semiconductor substrate, a first ZnO-based semiconductor layer having a first conductivity type formed on the + C-plane side of the C-plane ZnO-based semiconductor substrate, and the first ZnO A second ZnO-based semiconductor layer formed above the semiconductor layer and having a second conductivity type opposite to the first conductivity type;
Forming a contour groove deeper than a depth at which the first ZnO-based semiconductor layer is exposed from the + C plane side in the ZnO-based semiconductor member;
In the scribing step, the scribe groove is formed so as to extend in a length direction of the bottom below the bottom of the contour groove, and in the breaking step, the cleavage member is formed on the bottom of the contour groove. The method of manufacturing a ZnO-based semiconductor device according to claim 1, wherein the method is pressed along the length direction of the bottom.   3. The method for manufacturing a ZnO-based semiconductor device according to claim 1, wherein in the scribing step, the scribe groove is formed with a four-point heel point tool.   The said scribing process is a manufacturing method of the ZnO type | system | group semiconductor device of Claim 3 which makes the blade edge angle of the said 4 point heel point tool into the range of 50 degrees-54 degrees, and makes the blade edge load into the range of 80 g-120 g.   5. The ZnO-based semiconductor device according to claim 1, wherein the scribing step forms a scribe groove extending in the a-axis direction and a scribe groove extending in the m-axis direction on the −C plane. Manufacturing method. It is made of a ZnO-based semiconductor having a wurtzite structure. The upper surface is a + C plane and the lower surface is a -C plane. A scribe groove is formed at the edge on the -C plane side, and is broken by braking by load cleavage from the + C plane side. A first portion having an end face formed thereon;
A first ZnO-based semiconductor layer having a first conductivity type is disposed on a region extending inward from the edge of the + C plane of the first portion, and is formed above the first ZnO-based semiconductor layer. And a second portion including a second ZnO-based semiconductor layer having a second conductivity type opposite to the first conductivity type.   7. When a plane including the scribe groove and inclined by 18 ° from the normal direction of the −C plane is considered, a position where the plane and the + C plane intersect is disposed outside the second portion. A ZnO-based semiconductor device described in 1.