JP5136398B2 - Group III nitride compound semiconductor light emitting device - Google Patents

Description

The present invention relates to a group III nitride compound semiconductor light emitting device. The present invention relates to a group III nitride compound semiconductor light-emitting device which is bonded to a conductive support substrate from the p-layer side through a layer made of a conductive material and has a light extraction side as an n-layer side.
In the present invention, a group III nitride compound semiconductor is epitaxially grown on a heterogeneous substrate to form a light emitting device structure, and then a conductive support substrate is bonded via a metal, solder, or other conductive layer, and an interface with the heterogeneous substrate is obtained. The present invention can be applied to a light emitting device using a so-called laser lift-off technique in which a thin layer of a nearby group III nitride compound semiconductor is decomposed by laser irradiation to remove a different substrate. The present invention is a group III nitride compound semiconductor light emitting device having an n-type layer and a p-type layer above and below a pn junction or an active layer.

Patent Document 1 discloses a method for manufacturing a group III nitride compound semiconductor light emitting device using a so-called laser lift-off technique by the present inventors. The outline of the light emitting device described in Patent Document 1 is a group III nitride bonded to a conductive support substrate from the p layer side through a layer made of a conductive material and having the light extraction side as the n layer side. This is a compound semiconductor light emitting device. The n-layer side electrode provided on the light extraction side is not usually a translucent electrode but is formed of a metal or alloy that forms ohmic contact. At this time, since the n contact electrode provided in the n layer serves as a shield against light extraction, it is necessary to devise a method for supplying a current as uniformly as possible to the entire light emitting region.
JP2007-158128

  In the group III nitride compound semiconductor light emitting device manufactured by laser lift-off and having the light extraction side as the n layer side, the contact area between the p layer and the p contact electrode can be increased, and The constituent material of the p-contact electrode can be selected with the contact resistance as the main selection condition. For this reason, the light emitting element manufactured by laser lift-off is useful as a large element having a planar shape of, for example, 1 mm square, which allows a large current to flow, as compared with a group III nitride compound semiconductor light emitting element having another configuration. Here, since the n-contact electrode provided on the light extraction side serves as a shield against light extraction, there is room for improvement in the design of the n-contact electrode.

  Accordingly, an object of the present invention is to suppress the effect that the n contact electrode becomes an obstacle to light extraction in a group III nitride compound semiconductor light emitting device manufactured by laser lift-off and having the light extraction side as the n layer side. is there.

The main feature of the present invention is that a large-area region for connecting an external wiring among n-contact electrodes serves as a shield against light extraction, so that the entire n layer immediately below the region does not serve as a current path. By doing so, light emission from directly under the n-contact electrode, which is a shield, is suppressed, and the ratio of light emission that can be extracted to the outside with respect to the supply current is improved. In addition, according to the present invention, by defining the planar shape of the n-contact electrode that serves as a shield, the current is uniformly supplied to the region that should be the actual light emitting region of the light emitting layer, and the light emitting region is caused to emit light uniformly. It is.
The invention according to claim 1 is a group III nitride compound in which an epitaxial layer is bonded to a conductive support substrate through a layer made of a conductive material from the p layer side, and the light extraction side is the n layer side A semiconductor light-emitting element, a p-contact electrode bonded to the p-layer and leaving the outer peripheral surface of the p-layer, a conductive layer covering the entire p-contact electrode and bonded without making ohmic contact with the p-layer on the outer peripheral surface; has a planar shape of the n layer as seen from the light extraction side is rectangular, n-contact electrode provided on the n layer functions as a bonding pad provided near two opposite corners of the rectangular shape 2 It consists of two large area portions and a linear portion extended from the two large area portions. At least a part of the two large area portions facing the n layer is in ohmic contact with the n layer. you Razz, n layers of the two large-area portion The portion that is not in ohmic contact is a region in which an insulating film is formed between the n layer and the two large area portions, and the insulating film is integrated with a protective film that covers the outer peripheral side surfaces of the n layer and the p layer. The linear portion of the n-contact electrode has a rectangular frame-shaped outer peripheral line portion, and is connected to two large area portions at two vertices of the rectangular shape of the outer peripheral line portion. The shape portion has an inner line portion formed so as to divide the surface of the n layer surrounded by the outer peripheral line portion, and is on the surface of the p layer that contacts the p contact layer, and has a large area portion In the group III nitride compound semiconductor light emitting device, a high resistance surface is formed in a region located below the outer peripheral line portion, and the other region is a low resistance surface .
The bonding pad refers to a large-area conductor region for connecting an external wiring to the exposed upper surface. At this time, general wire bonding is used to connect external wiring. In addition, a conductive material such as solder may be used, or another conductive material may be stacked on a large area portion of the n-contact electrode formed in the bonding pad region. The large area portion of the n-contact electrode of the present invention does not exclude such a laminated structure.
Further, the n-contact electrode of the present invention is not limited to an electrode made of a single material even in the linear portion. The n-contact electrode having a large area portion and a linear portion in the present invention includes those having a multilayer structure of a conductive material having good ohmic properties and other conductive materials .

The invention according to claim 2 is characterized in that the high resistance surface is formed by ion implantation from a surface of the p layer into a region where the high resistance surface is formed, or by plasma treatment of the region.
The invention according to claim 3 is characterized in that, in the linear portion of the n-contact electrode, the width of the inner line portion is smaller than the width of the outer peripheral line portion.
According to a fourth aspect of the present invention, when each part of the linear part of the n-contact electrode is set to L and the film thickness of the n layer is t with respect to the other part of the linear part arranged in parallel, 10 It is arranged at a position satisfying ≦ L / t ≦ 80.
In the invention according to claim 5 , the portion that is in ohmic contact with the n layer of the large area portion is a strip-shaped or bent strip-shaped having a width, and the width is the same as the width of the outer peripheral line portion of the n-contact electrode. It is more than 2 times or less.
The invention according to claim 6 is characterized in that the rectangular shape of the outer peripheral line portion is a parallelogram, a rhombus, a rectangle, or a square.
In the invention according to claim 7 , the planar shape of the n-contact electrode is point-symmetric with respect to the center of gravity of the planar shape of the n layer, or two large area portions of the rectangular n-layer are not provided. It is characterized by line symmetry with respect to a line segment connecting two vertices.

The invention according to claim 8 is characterized in that at least one of the conductive materials formed between the conductive support substrate and the p layer is a solder layer. Here, the solder layer refers to an alloy that melts or has fluidity at a temperature of approximately 400 degrees or less.
According to the ninth aspect of the present invention, at least an n layer is formed on an epitaxial growth substrate made of a different type substrate, a p layer is formed, and after bonding to a conductive support substrate through at least a solder layer, the epitaxial growth substrate is laser-bonded. It was manufactured by removing by lift-off. The heterogeneous substrate refers to a substrate made of a material different from the group III nitride compound semiconductor constituting the epitaxial layer. For example, a sapphire substrate is included in the heterogeneous substrate mentioned here.
The invention according to claim 10 is characterized in that the outer peripheral side surfaces of the n layer and the p layer are forward tapered inclined surfaces that spread from the n layer side, which is the light extraction side, to the p layer side. The forward taper means that the horizontal cross-sectional area is narrow on the upper side and the horizontal cross-sectional area is wide on the lower side, like the side surface of the weight-like object.

Although a bonding pad portion for external connection is an indispensable structure as a light emitting element, when an electrode that is not translucent is used for the region, light from the light emitting region immediately below is completely blocked. If the entire bonding pad portion is brought into ohmic contact with the n layer, current flows from the bonding pad portion to the n layer even if there is no portion that becomes a light emitting region immediately below the large area portion that functions as the bonding pad portion. The layer propagates laterally and concentrates in the nearby light emitting region. By providing a region that does not make ohmic contact with the bonding pad portion, the current supplied to the light emitting element can be distributed to the entire light emitting region .
In this configuration, it is preferable to form a portion that cannot be in ohmic contact with the insulating layer, and to form a large area portion of the n contact electrode across the insulating layer and the n layer that is in ohmic contact. Here, the intention of forming the n-contact electrode across the two parts is to avoid disconnection between the large area part acting as a bonding pad part and the linear part provided by being extended therefrom. . If the linear portion is formed over the insulating layer and the n layer to be in ohmic contact, the possibility of disconnection increases due to a step at the edge portion of the insulating layer. If the large area portion is formed across the insulating layer and the n layer, the large area portion of the n contact electrode provided on the n layer and the linear portion provided by extending from the n layer since the step is not generated between, as possible out to suppress the possibility of breakage.
In the group III nitride compound semiconductor light emitting device, the outer peripheral side surface (cross section) of the epitaxial growth layer is avoided in order to avoid undesired electrical connection between the p layer and the n layer due to adhesion of the conductive material after manufacturing or during the manufacturing process. ) Is generally protected by an insulating film. Therefore, when the protective film is formed, if the protective film is integrally formed in the region that prevents the ohmic contact between the large area portion of the n contact electrode and the n layer, the manufacturing process can be simplified. Yes.

If the light-emitting element has a rectangular shape, the epitaxial growth layer may have a rectangular shape, and the uppermost n layer may have a rectangular shape. In order to supply current uniformly to the rectangular light emitting layer region, a linear portion (peripheral line portion) of a smaller rectangular frame-shaped n-contact electrode is formed in accordance with the rectangular outer periphery of the epitaxial growth layer. desired arbitrariness. For example, in the case of a 1 mm square shape, the outer peripheral line portion of the linear portion of the electrode is preferably formed in a square outer frame shape of 0.5 to 0.95 mm square.
If it is difficult to equalize the current supplied to the wide light emitting region only by the outer peripheral line portion, the inner line portion is formed so as to divide the surface of the n layer in the region surrounded by the outer peripheral line portion, An n-contact electrode may be extended inside a region surrounded by the line portion . The inner line portion may be provided in a straight line or a lattice shape parallel to one side of the outer peripheral line portion, for example, by dividing the rectangular shape surrounded by the outer peripheral line portion into smaller rectangular shapes. If a grid is formed, even if disconnection or the like occurs in a part of the inner line portion, multiple current supply paths to both sides of the disconnection point are secured, and current supply is ensured at least to both sides of the disconnection point. Done.

Although it may be considered that the inner line portion finally serves only to supply current to the n layer, the outer peripheral line portion also serves to distribute current to the inner line portion. Therefore, since it is considered that the inner line portion has a smaller amount of current, it is preferable to reduce the light extraction shielding effect of the inner line portion by making the width of the inner line portion smaller than the width of the outer line portion . For example, the width of the outer track portion may be increased by 20% to 80% of the width of the inner track portion.
Each part of the linear part of the n-contact electrode satisfies 10 ≦ L / t ≦ 80, where L is the distance from the other part of the linear part arranged in parallel and t is the film thickness of the n layer. It is good to arrange in the position. When L / t is less than 10, for example, a large number of inner line portions having a width of several μm to several tens of μm are arranged in parallel at a narrow interval, and the light extraction shielding effect of the entire n contact electrode becomes too large. End up. When L / t exceeds 80, the current supply from the adjacent linear portions of the n-contact electrode to the n-layer in the central portion becomes insufficient, resulting in a light-emitting defective region in the light-emitting layer that should emit light satisfactorily. and Te Mau. More preferably, 20 ≦ L / t ≦ 60.

The portion in ohmic contact with the n layer in the large area portion is a strip having a width or a bent strip, and the width is preferably equal to or more than twice the width of the outer peripheral line portion of the n contact electrode. When a large area part to be a bonding pad is arranged at the two apexes of the outer peripheral line part having a rectangular planar shape, the outer periphery of the large area part is an extension part of the outer peripheral line part, and current is supplied in the same manner as the outer peripheral line part. It is preferable to function as a part.
If the width of the portion in ohmic contact with the n layer of the large area portion is narrower than the outer peripheral line portion, there is a risk of disconnection from the outer peripheral line portion. On the other hand, when more than 2 times the width of the outer line portion becomes a current flows in a concentrated from the bonding pad portion in the light emitting region near through n layer, undesirable.

n-contact electrode is planar shape axisymmetric or point symmetry, from the large-area portion of the n-contact electrode serving as two bonding pads, equally preferred to design so that a current is supplied arbitrarily.
The present invention is particularly effective for a light emitting device manufactured by laser lift-off .

  Since the present invention can be applied to a group III nitride compound semiconductor light-emitting device manufactured by laser lift-off, a known arbitrary material is selected as long as the laser lift-off technique can be applied, and any known manufacturing The method can be adopted.

  For the n-contact electrode, a conductive material having a low ohmic resistance with the n-layer may be used at a portion in contact with the n-layer composed of at least a group III nitride compound semiconductor. For example, a double layer of aluminum (Al) and another metal Or it is good to make more than that multiple layers. In this case, the present invention also includes a structure in which aluminum (Al) is not used in a portion where ohmic contact with the n layer is not desired, and only a thick metal layer formed thereon is formed.

Of the n-contact electrodes, the planar shape and area of the large area part functioning as a bonding pad part can be arbitrarily designed. Circular, oval, rectangular, etc. For example, it may be a square having a side of 50 μm or more. In this case, the maximum value of one side of the large area of the square depends on the size of the entire light emitting element.
Of the n contact electrodes, the width of the linear portion is preferably 5 μm or more and 40 μm or less. It is technically difficult to form a linear n-contact electrode having a width of less than 5 μm, and the possibility of disconnection during use after production becomes high. If the width exceeds 40 μm, the light extraction shielding effect becomes too large, which is not preferable.
In the linear part, the width of the frame-shaped outer peripheral line part directly connected to the large area part functioning as the bonding pad part is preferably larger than the width of the inner line part. For example, the width of the outer track portion is increased by 20% to 80% of the width of the inner track portion. For example, the width of the outer peripheral line portion is preferably 8 μm or more and 40 μm or less, and more preferably 10 μm or more and 30 μm or less. The width of the inner line portion is preferably 5 μm or more and 30 μm or less, and more preferably 7 μm or more and 25 μm or less.
The planar shape of the outer peripheral line portion is a rectangular frame shape, and the inner line portion is formed as a plurality of line segments dividing the inside of the frame into a rectangular shape or a lattice shape. When forming with two groups of parallel lines, the interval L between two adjacent linear portions parallel to each other is preferably 50 μm or more. As a result of providing a large number of linear portions with a thickness of less than 50 μm, the light extraction shielding effect of the linear portions becomes too great. The distance L between two adjacent linear portions is preferably 70 μm or more and 500 μm or less, and more preferably 100 μm or more and 300 μm or less.

  In addition to the method of inserting an insulating film between the n layers of the n contact electrodes and the ohmic contact, a metal or other conductive layer having a high ohmic resistance or a Schottky connection is used. You may employ | adopt the method of inserting between. Alternatively, a conductive material having a low ohmic resistance with respect to the n layer, such as aluminum (Al), may be partially used at a portion where the n contact electrode and the n layer are in ohmic contact. In this case, a conductive material having a low ohmic resistance is not provided in the n layer portion where ohmic contact with the n contact electrode is not desired. Furthermore, a method of removing the ohmic property with the n-contact electrode in this region by performing plasma processing or ion implantation only on the region of the n layer where ohmic contact with the n-contact electrode is not desired. May be.

FIG. 1 is a cross-sectional view showing a configuration of a light emitting diode (group III nitride compound semiconductor light emitting device) 1000 according to a specific embodiment of the present invention, and FIG. 2 is a view of the light emitting diode 1000 at a position different from FIG. FIG. 1 and 2 are cross-sectional views at positions indicated as II and II-II in FIG. 7, which is a plan view shown later.
The light-emitting diode 1000 of FIGS. 1 and 2 includes a conductive layer 222 made of a stack of a plurality of metals and a solder layer (solder layer) on the surface of a conductive support substrate 200 that is a p-type silicon substrate. Layer) 50, a conductive layer 122 made of a stack of a plurality of metals, a p-contact electrode 121, a p-type layer 12, which is a single layer or a multiple layer of a p-type group III nitride compound semiconductor layer, a light-emitting layer 15, mainly It has a laminated structure of an n-type layer 11 that is a single layer or multiple layers of an n-type group III nitride compound semiconductor layer, an outer peripheral line portion 130f that is an n-contact electrode, an inner line portion 130g, and a large-area portion 130p.
The light emitting layer 15 has, for example, an MQW structure, but is simply indicated by a thick broken line in FIGS.
The outer peripheral line portion 130f, the inner line portion 130g, and the large area portion 130p, which are n contact electrodes, form an n contact electrode that is connected and integrated at a position (not shown), and by wire bonding to the large area portion 130p, The outer peripheral line portion 130f, the inner line portion 130g, and the large area portion 130p have substantially the same potential. In FIG. 1, the outer peripheral line portion 130f and the inner line portion 130g are shown, and in FIG. 2, only the large area portion 130p is shown.
The surface of the p-type layer 12 that contacts the p-contact electrode 121 or the conductive layer 122 is divided into a high-resistance surface 12sr, low-resistance surfaces 12s-sq and 12s-L, and an outer peripheral surface 12sf that does not make ohmic contact. There is no p-contact electrode 121 on the outer peripheral surface 12 sf, and the p-type layer 12 is in direct contact with the conductive layer 122. Of these, the high resistance surface 12sr is indicated by a bold line in FIGS.
The high resistance surface 12sr of the p-type layer 12 was formed by performing ion implantation or plasma treatment only on the region after the p-type layer 12 was formed. In the case of forming the light emitting diode 1000 using laser lift-off, the p-type layer 12 can be the uppermost layer by epitaxially growing a group III nitride compound semiconductor layer on an epitaxial growth substrate. Ion implantation or plasma treatment is partially performed on the surface of the p-type layer 12 that is the exposed surface. Thus, finally, as shown in FIGS. 1 and 2, the high resistance surface 12 sr can be formed on the contact surface side between the p-type layer 12 and the p contact electrode 121.

When the description in the claims is compared with the configuration of the present embodiment, the layer corresponding to the “layer made of a conductive material” in claim 1 is the conductive layer 222, the solder layer (solder layer) 50, the conductive layer. 122 and the p-contact electrode 121.
The outer peripheral side surfaces of the p-type layer 12, the light emitting layer 15, and the n-type layer 11 are covered with an insulating protective film 40. Further, the p-type layer 12, the light-emitting layer 15, and the n-type layer 11 (hereinafter sometimes collectively referred to as the epitaxial layer 10) have a horizontal cross-sectional area parallel to the surface of the support substrate 200. 12 gradually decreases from the support substrate side 200 side toward the n contact electrode 130 side of the upper n-type layer 11. Therefore, the outer peripheral side surface of the epitaxial layer 10 covered with the insulating protective film 40 is inclined (in order) so as to spread from the upper side where the n contact electrode 130 is formed to the lower side which is the support substrate side 200 side. Taper).
The n-type layer 11 has a surface 11s having fine irregularities in order to improve light extraction efficiency.
In addition, a conductive layer 232 and a solder layer (solder layer) 235 made of a stack of a plurality of metals are formed on the opposite surface (back surface) of the support substrate 200.

In this embodiment, each layer is configured as follows.
The conductive layer 222 composed of a plurality of metal layers is formed by stacking titanium (Ti), nickel (Ni), and gold (Au) in this order from the support substrate 200 side. The conductive layer 232 including a plurality of metal layers is formed by stacking platinum (Pt), titanium (Ti), nickel (Ni), and gold (Au) in this order from the support substrate 200 side. The nickel (Ni) layer prevents diffusion of tin (Sn) contained in the solder layer (solder layer) 50.
The solder layers (solder layers) 50 and 235 are each formed of solder made of an alloy of gold and tin (Au—Sn). Note that a thin gold (Au) layer for preventing oxidation of tin is formed on the surface of the solder layer (solder layer) 235.
The p contact electrode 121 is made of a silver (Ag) alloy.
The conductive layer 122 made of a stack of a plurality of metals has titanium (Ti), titanium nitride (TiN), titanium (Ti), nickel (Ni), gold (Au) from the side close to the p-type layer 12 and the p contact electrode 121. ) Are stacked in this order.
The n-contact electrode 130 has a laminated structure in which aluminum (Al), titanium (Ti), nickel (Ni), and gold (Au) are laminated in this order from the n-type layer 11 side.
The insulating protective film 40 is made of silicon nitride (Si ₃ N ₄ ).
The insulating protective film 40 corresponds to both the insulating film and the protective film described in the claims.

FIG. 3 is an enlarged cross-sectional view of the laminated structure from one of the outer peripheral line portion 130f or the inner line portion 130g of the n-contact electrode to the p-contact electrode 121 in the cross-sectional view of the light emitting diode 1000 of FIG. It is.
The longitudinal direction of the linear outer periphery line portion 130f or the inner line portion 130g is formed in a direction perpendicular to the paper surface of FIG. The width (line width) in the left-right direction in FIG. 3 of the linear outer periphery line portion 130f or the inner line portion 130g is set to wf or wg. The p-contact electrode 121 at a position opposite to these is not in ohmic contact with the p-type layer 12 due to the high resistance surface 12sr formed on the surface of the p-type layer 12, or the contact resistance becomes extremely high. The high resistance surface 12sr is a rectangular region having a width wf + 2d or wg + 2d having a longitudinal direction in accordance with the longitudinal direction of the linear outer peripheral line portion 130f or the inner line portion 130g.
Since the p-type layer 12 has a relatively high resistance, when current is blocked by the high resistance surface 12sr, no current flows in the region of the width wf + 2d or wg + 2d of the upper light emitting layer 15 corresponding to the high resistance surface 12sr. This region is a non-light emitting region 15nLE. The region of the light emitting layer 15 where the current is not blocked by the high resistance surface 12sr is the light emitting region 15LE that actually emits light.

Here, in the cross-sectional view of FIG. 3, the right end point EP-12sr of the high-resistance surface 12sr, and the point EP-LEL (end point where light can be emitted) on the boundary between the non-light emitting region 15nLE and the light emitting region 15LE of the light emitting layer 15 immediately above it. ), The right end point EP-130 of the contact surface with the surface 11s of the n-type layer 11 of the linear outer peripheral line portion 130f or the inner line portion 130g is considered. The angle between the line segment connecting the point EP-LEL and the point EP-130 and the vertical direction (perpendicular to the substrate surface of the light emitting diode 1000) in FIG. When the film thickness of the n-type layer 11 is t, tan θ = d / t (FIG. 3).
The film thickness t of the n-type layer 11 is 2 μm to 10 μm, preferably 3 μm to 6 μm, the horizontal width wf of the linear outer peripheral line portion 130 f is 8 μm or more and 40 μm or less, and the horizontal direction of the inner line portion 130 g is Considering that the width wg should be 5 μm or more and 30 μm or less, it is considered that d is preferably t / 2 or more and 5 t or less. The n-type layer 11 having a thickness of 10 μm or less has a higher resistance as the current path becomes longer. In addition, the lateral distance (minimum d) of the current path inside the n-type layer 11 of the thin film should not be too large. In this respect, the optimum range of d is shown in a proportional relationship with the film thickness t. sell.
The minimum value of d should be set so that the angle range blocked by the linear outer line portion 130f or the inner line portion 130g in the light from the end point EP-LEL of the light emitting region 15LE is not too large. When d = t / 2, tan θ = d / t = 1/2 and θ is about 26.6 degrees, that is, when light emitted from the end point EP-LEL of the light emitting region 15LE is perpendicular to the substrate surface at an angle 0. The light having an angle exceeding about 26.6 degrees is blocked by the linear outer peripheral line portion 130f or the inner line portion 130g, which is an n-contact electrode. If the angle range to be shielded is larger than this, the light extraction efficiency is reduced. The formation of the n contact electrodes (130f, 130g) needs to be aligned with the arrangement of the p contact electrode 121. At this time, the p-contact electrode 121 needs to be recognized through the epitaxial layer 10, and the alignment position is shifted if accurate alignment is not possible. In order to prevent the n-contact electrodes (130f, 130g) from being formed on the light emitting region 15LE, there is an appropriate minimum value of d corresponding to the thickness of the epitaxial layer 10. Most of the change in the film thickness of the epitaxial layer 10 is due to the change in the film thickness t of the n-type layer 11. When alignment is performed with various film thicknesses, light emission is surely achieved when d ≧ t / 2. It was found that the n contact electrodes (130f, 130g) were not formed on the region 15LE.
On the other hand, if d is too large, the current component that propagates laterally in the n-type layer 11 increases, and the drive voltage increases due to the voltage drop due to the sheet resistance component of the n-type layer 11. By setting the maximum value of d to 5t, this voltage increase can be suppressed to less than 0.1V. Further, if d is too large, the area of the light emitting region 15LE becomes small, which is not preferable.

FIG. 4 is an enlarged view of the stacked structure from the large area portion 130p of the n contact electrode functioning as a bonding pad portion for wire bonding to the conductive layer 122 in the cross-sectional view of the light emitting diode 1000 of FIG. FIG.
The large area portion 130p, which is a part of the n-contact electrode, is formed, for example, in a rectangular shape in plan view, and one set of two sides facing each other is parallel to the horizontal direction in the plane of FIG. Assume that the sides are formed in a direction perpendicular to the paper surface of FIG. The large area portion 130p of FIG. 4 communicates with the linear outer periphery line portion 130f of FIG. 3 at a position not shown, and the linear outer periphery line portion 130f of FIG. 3 is illustrated with the linear inner line portion 130g of FIG. It is communicated at a position that does not. That is, the large area portion 130p in FIG. 4 forms an n-contact electrode for the n-type layer 11 together with the linear outer peripheral line portion 130f and the inner line portion 130g in FIG. This is shown later in FIG.

As shown in FIG. 4, the large-area portion 130 p that is a part of the n-contact electrode includes a contact region 130 pc that is a portion where the lower surface is in contact with the surface 11 s that is a fine uneven surface of the n-type layer 11, The non-contact region 130p-i is a portion where the insulating protective film 40 is inserted between the n-type layer 11 and the n-type layer 11. The width of the contact region 130p-c, which is a portion in contact with the surface 11s of the n-type layer 11 of the large area portion 130p, is set as wp. A contact region 130p-c, which is a portion in contact with the surface 11s of the n-type layer 11 of the large area portion 130p, is a belt-like region having a planar shape of width wp, and its longitudinal direction is perpendicular to the paper surface of FIG. Shall.
The contact region 130p-c, which is a portion in contact with the surface 11s of the n-type layer 11 of the large area portion 130p, is a linear outer peripheral line in contact with the surface 11s of the n-type layer 11 shown in FIG. It is connected to the portion 130f at a position not shown. This is shown later in FIG. Here, in order to prevent disconnection of the connection portion, the width wp of the contact region 130p-c of the large area portion 130p needs to be greater than or equal to the width wf of the linear outer peripheral line portion 130f. On the other hand, the width wp of the contact region 130p-c of the large area portion 130p is a shielding region for light emission from the light emitting region 15LE.
Therefore, the high resistance surface 12sr of the p-type layer 12 is formed from the right end point EP-R to the point EP-L of the p-contact electrode 121 at the interface between the p-type layer 12 and the p-contact electrode 121 as shown in FIG. To do. The high resistance surface 12sr is formed to extend outward by a width dp from the region immediately below the large area portion 130p at the interface between the p-type layer 12 and the p contact electrode 121. Since the current path from the p-contact electrode 121 is blocked at the high-resistance surface 12sr of the p-type layer 12, the current is directed only upward from the low-resistance surface 12s-L. Thus, in the light emitting layer 15, the portion 15 nLE 40 that is directly below the insulating protective film 40, the portion 15 nLE 130 that faces the width wp of the portion that is in contact with the surface 11 s of the n-type layer 11 of the large area portion 130 p of the n contact electrode. In addition, the non-light-emitting region 15nLE is formed by extending outward by a width dp (15nLE12sr).
Of the high resistance surface 12sr of the p-type layer 12 in FIG. 4, the width dp shown in FIG. 4 is the high resistance of the p-type layer 12 facing the linear outer line portion 130f or the inner line portion 130g described in FIG. For the same reason as the width wf + 2d or wg + 2d of the surface 12sr, the maximum value should be 5t. Here, t is the average film thickness of the n-type layer 11. The minimum value may be d. By so doing, the portion that is in contact with the surface 11s of the n-type layer 11 of the large-area portion 130p that is a part of the n-contact electrode is caused to function in the same manner as the linear outer peripheral line portion 130f or the inner line portion 130g. Is possible.
Also, the maximum value of the width wp of the contact region 130p-c, which is the portion in contact with the surface 11s of the n-type layer 11 of the large area portion 130p, of the high resistance surface 12sr of the p-type layer 12 in FIG. It is good to set it as twice the width wf of the linear outer periphery line | wire part 130f connected. This is because it should be avoided that the current in the bonding pad portion flows through the n layer, propagates laterally through the n layer, and concentrates in a nearby light emitting region.

  The above is a description of the features of the first embodiment with reference to cross-sectional views. The first embodiment will be further described with reference to plan views in FIGS.

  FIG. 5 shows the high resistance surface 12 sr, the low resistance surfaces 12 s-sq and 12 s-L, and the p contact electrode 121 on the side of the light emitting diode 1000 according to Example 1 that is in contact with the p contact electrode 121. It is a top view which shows the division of outer peripheral surface 12sf which does not make ohmic contact.

A square ABCD having a side of 900 μm in FIG. 5 indicates the outer periphery of the light emitting diode 1000.
A square EFGH having a side of 800 μm in FIG. 5 indicates the outer periphery of the p-type layer 12 of the light emitting diode 1000.
A square PQRS having a side of 680 μm in FIG. 5 indicates the outer periphery of the p contact electrode 121.
In FIG. 5, six points A, E, P, R, G, and C are arranged on a straight line, and six points B, F, Q, S, H, and D are arranged on a straight line.
The same applies to FIGS. 6 and 7. 5 to 7, the plan views shown are line symmetric with respect to the straight line AC and line symmetric with respect to the straight line BD. 5 to 7 are point-symmetric with respect to the intersection of the straight line AC and the straight line BD.

First, in FIG. 5, the p-type layer 12 is an internal region of a square EFGH. This is divided into the following four categories.
First, there is an outer peripheral surface 12sf that is a region not in contact with the p-contact electrode 121 indicated by the inner region of the square PQRS. This is a frame-like region having a width of 60 μm inside the square EFGH and outside the square PQRS.
Next, the shape of the two low resistance surfaces 12s-L in the region of the p-type layer 12 in contact with the p-contact electrode 121 is as follows. This shape is an L-shaped region in which two rectangles with a long side of 560 μm and a short side of 70 μm are overlapped by a square portion with a side of 70 μm, which is the end of each, and bent at two vertices inside the square PQRS at the apex Q Are arranged in the area where the external vertex of the part is placed and the area where the external vertex of the bent part is placed on the vertex S.
Of the region in contact with the p-contact electrode 121, nine low-resistance surfaces 12s-sq have the following shapes. This is a square region with a side of 130 μm arranged at nine places, and these nine are arranged with a gap of 35 μm from the next. The nine low resistance surfaces 12s-sq are all arranged inside a square region having one side of 130 × 3 + 35 × 2 = 460 μm. As described above, the nine low-resistance surfaces 12s-sq are arranged so as to be symmetric about the straight line AC and symmetric about the straight line BD in FIG.
Thus, the remaining area of the inner area of the square PQRS is the high resistance surface 12sr. The high resistance surface 12sr is formed by overlapping a substantially square region having apexes at the apex P and the apex R and eight belt-like regions having a width of 40 μm and a width of 35 μm.
Thus, current flows from the p-contact electrode 121 to the p-type layer 12 via the low-resistance surface 12s-L and the low-resistance surface 12s-sq shown by hatching from upper right to lower left in FIG. Since the p-type layer 12 has a relatively high resistance and a film thickness of 500 nm or less, the current path from the p-type layer 12 to the light emitting layer 15 is perpendicular to the substrate surface, that is, in the plane of FIGS. It can be considered that it is only in the vertical direction. Then, in the light emitting layer 15, the shape of the light emitting region 15 LE that actually emits light coincides with the regions of the low resistance surface 12 s-L and the low resistance surface 12 s-sq shown by hatching from the upper right to the lower left in FIG. You can think about it.

  6 shows the arrangement of the surface 11s of the n-type layer 11 of the light-emitting diode 1000 according to the first embodiment, the insulating protective film 40, the large area portion 130p forming the n-contact electrode, the outer peripheral line portion 130f and the inner line portion 130g. It is the shown top view. Here, of the large-area portion 130p forming the n-contact electrode, the portion in ohmic contact with the n-type layer, the outer peripheral line portion 130f and the inner line portion 130g are shown by hatching from the upper left to the lower right, and the insulating protective film 40 The portion formed with is shown by hatching at 75 degrees from the upper right to the lower left.

In FIG. 6, a square EFGH indicates the outer periphery of the n-type layer 11 of the light emitting diode 1000, and is a square having one side of 800 μm. In the light emitting diode 1000, the epitaxial layer 10 has a forward taper as shown in FIGS. 1 and 2, but in FIGS. 5 to 7, the taper is ignored and the outer periphery of the n-type layer 11 and the p-type layer are ignored. A plan view is created on the assumption that the outer circumferences of 12 coincide.
Actually, when the total thickness of the epitaxial layer is 2 to 10 μm, 90 degrees is vertical and the taper is 75 degrees, the outer periphery of the uppermost surface of the n-type layer 11 and the lowermost surface of the p-type layer 12 Consider the perimeter. If the uppermost square of the n-type layer 11 is accurately described on the assumption that the lowermost surface of the p-type layer 12 is a square EFGH with one side of 800 μm, the gap 0.53 to the inner side of the square EFGH with one side of 800 μm. Four sides will be described at 2.8 μm.

The width of the insulating protective film 40 is not described in the present invention because it does not matter in the present invention except for the portion located below the large area portion 130p forming the n contact electrode.
Two large-area portions 130p for forming the n-contact electrode are formed, and are arranged so as to share vertices P and R in an inner region of a square PQRS having a side of 100 μm and a side of 680 μm. The Of the two large-area portions 130p that form the n-contact electrode, the two non-contact regions 130p-i in which the insulating protective film 40 is formed in the lower layer are square regions with one side of 70 μm, The vertices P and R are arranged to share each other. The L-shaped region having a width wp of 30 μm, excluding the non-contact region 130p-i of the large area part 130p, is a contact region 130pc that is in ohmic contact with the surface 11s of the n-type layer 11.
The outer peripheral line portion 130f forming the n contact electrode has a square frame shape with a width wf of 20 μm, and one side of the outer peripheral square is 520 μm and one side of the inner peripheral square is 480 μm. The square part with one side of 20 μm, which is the apex of two places of the square frame, overlaps with the large area part 130p forming the n contact electrode.
The inner line portion 130g has four strips with a width wg of 15 μm, and the inner region surrounded by the square frame-shaped outer peripheral line portion 130f is divided into nine regions. Each of the nine regions surrounded by the outer track portion 130f and the inner track portion 130g is a square having a side of 150 μm.
A portion not hatched in FIG. 6 is the exposed surface 11 s of the n-type layer 11.
Further, in this embodiment, as shown in FIG. 6, the design is such that there is no ohmic contact region with the n-type layer 11 of the n-contact electrode outside the square PQRS indicating the formation range of the p-contact electrode 121. The present invention is not limited to this. The range of the ohmic contact region of the n contact electrode with the n-type layer 11 may exceed the formation range in the plan view of the p contact electrode 121 formed below.

7 shows the regions of the low resistance surfaces 12s-L and the low resistance surfaces 12s-sq shown by hatching from the upper right to the lower left in FIG. 5, and the n-type shown by hatching from the upper left to the lower right in FIG. It is the top view which overlapped and showed the contact region 130pc of the large area part 130p, the outer periphery line | wire part 130f, and the inner side line part 130g which are in ohmic contact with the layer 11. FIG.
The outer line portion 130f and the inner line portion 130g, and the regions of the low resistance surface 12s-L and the low resistance surface 12s-sq have a band-like or square frame-like gap having a width of d = 10 μm in the plan view. . Further, the contact region 130p-c of the large area portion 130p and the low resistance surface 12s-L have a band-like gap having a width of dp = 20 μm in the plan view.
7 is a cross-sectional view at a position indicated by II in FIG. 7, and FIG. 2 is a cross-sectional view at a position indicated by II-II in FIG.

The correspondence between the numerical values shown in FIG. 7 and the numerical limitations shown in the claims is as follows.
A width wg of 15 μm of the inner line portion 130g is smaller than a width wf of 20 μm of the outer line portion 130f.
An interval L between adjacent portions of the outer track portion 130f and the inner track portion 130g that are parallel to each other is 150 μm. When the thickness t of the n-type layer 11 is 2 μm, L / t = 75, and when the thickness t is 10 μm, L / t = 15.
The contact region 130p-c of the large area part 130p is an L-shaped region, and the width wp is 30 μm. This is greater than or equal to 20 μm width wf and less than or equal to 2 wf of the outer peripheral line portion 130f.

In the first embodiment, as illustrated in FIG. 5, nine low resistance surfaces 12 s-sq divided by four strip-shaped regions having a width of 35 μm in the high resistance surface 12 sr are arranged. Of the resistance surface 12sr, the four belt-like regions having a width of 35 μm may be low resistance surfaces. This is shown as Example 2.
FIG. 8 shows a high-resistance surface 12sr ′, low-resistance surfaces 12s-sq ′ and 12s-L, and a p-contact electrode on the side of the light-emitting diode 2000 according to Example 2 that is in contact with the p-contact electrode 121. 12 is a plan view showing a section of an outer peripheral surface 12sf that does not make ohmic contact with 121. FIG.
8 differs from FIG. 5 in that the low-resistance surface 12s-sq ′ is one square region having a side of 460 μm, and accordingly, the high-resistance surface 12sr ′ has no lattice-like region. . Others are exactly the same as in FIG. 5, and the same is true in that the plan view is symmetrical with respect to the straight lines AC and BD. For example, the low resistance surface 12s-sq ′ and the low resistance surface 12s-L are separated by a band-shaped region having a width of 40 μm of the high resistance surface 12sr ′.

9 and 10 are sectional views of the light emitting diode 2000 according to the second embodiment.
As shown in FIG. 9, in the light emitting diode 2000 according to Example 2, the high resistance surface 12sr ′ of the p-type layer 12 does not exist below the inner line portion 130g. This portion is one continuous low resistance surface 12s-sq '.
FIG. 10 is substantially similar to FIG.
The light emitting diode according to Example 2 is effective when the width wg of the inner line portion 130g is 20 μm or less. Preferably, the width wg of the inner line portion 130g is 10 μm or less.

  In Example 1 and Example 2 above, since the non-light-emitting region 15nLE is provided in the light-emitting layer 15, a desired region on the surface of the p-type layer 12 in contact with the p-contact electrode 121 is the high resistance surface 12sr or 12sr ′. However, before forming the p-contact electrode 121 in the p-type layer 12, for example, an insulating film or a film made of a material having a high contact resistance may be formed in a desired region. This case also has the same effect as the above embodiment.

Sectional drawing which shows the structure of the light emitting diode 1000 which concerns on one specific Example of this invention. Sectional drawing in another position which shows the structure of the light emitting diode 1000. FIG. The elements on larger scale of sectional drawing of FIG. 1 (sectional drawing). The elements on larger scale of sectional drawing of FIG. 2 (sectional drawing). The top view which shows arrangement | positioning of the high resistance surface of the p-type layer 12 of the light emitting diode 1000, a low resistance surface, and an outer peripheral surface. The top view which showed arrangement | positioning of the large area part 130p which forms the n contact electrode of the light emitting diode 1000, the outer periphery line | wire part 130f, and the inner line part 130g. FIG. 6 is a plan view showing an ohmic contact region between the low resistance surface of the p-type layer 12 of FIG. 5 and the n-type layer 11 of FIG. The top view which shows arrangement | positioning of the high resistance surface of the p-type layer 12 of the light emitting diode 2000 which concerns on the concrete other Example of this invention, a low resistance surface, and an outer peripheral surface. FIG. 3 is a cross-sectional view illustrating a configuration of a light-emitting diode 2000. Sectional drawing in another position which shows the structure of the light emitting diode 2000. FIG.

1000, 2000: Light emitting diode (Group III nitride compound semiconductor device)
11: n-type layer 12: p-type layer 12sr, 12sr ′: high-resistance surface of p-type layer 12 12s-sq, 12s-sq ′, 12s-L: low-resistance surface of p-type layer 12 12sf: p-type layer 12 15: light emitting layer 15LE: area of light emitting layer 15 that actually emits light (light emitting area)
15 nLE: a region of the light emitting layer 15 that does not actually emit light (non-light emitting region)
121: p-contact electrode 122, 222, 232: conductive layer 50: solder layer (solder layer)
130p: Large area portion of n contact electrode 130p-c: Portion in ohmic contact with n-type layer 11 in large area portion 130p 130pi: Portion in ohmic contact with n-type layer 11 in large area portion 130p : Outer contact line part of n contact electrode 130g: inner line part of n contact electrode 200: silicon substrate (support substrate)
40: Insulating protective film made of SiN

Claims (10)

A conductive support substrate, an epitaxial layer over the layer of conductive material is bonded from the p layer side, the light extraction side a III nitride compound semiconductor light-emitting element according to the n-layer side, the a p-contact electrode bonded to the p-layer and leaving the outer peripheral surface of the p-layer;
A conductive layer covering the whole of the p-contact electrode and bonded without making ohmic contact with the p-layer on the outer peripheral surface;
Have
The planar shape of the n layer viewed from the light extraction side is a rectangular shape,
N contact electrode provided on the n layer, and two large-area portion that functions as a bonding pad provided near two opposite corners of the rectangular shape, provided is drawn from the two large-area portion It consists of a linear part,
The two large-area portions, at least a portion thereof opposite to the n layer, an ohmic contact with contact Raz and the n layer,
The portion of the two large area portions that is not in ohmic contact with the n layer is a region in which an insulating film is formed between the n layer and the two large area portions,
The insulating film is integrated with a protective film covering outer peripheral side surfaces of the n layer and the p layer,
The linear portion of the n-contact electrode has a rectangular frame-shaped outer peripheral line portion, and is connected to the two large area portions at two vertices of a rectangle of the outer peripheral line portion,
The linear part of the n contact electrode has an inner line part formed so as to divide the surface of the n layer surrounded by the outer peripheral line part,
A high resistance surface is formed on a surface of the p layer that is in contact with the p contact layer, and located below the large area portion and the outer peripheral line portion, and the other region is a low resistance surface. A group III nitride compound semiconductor light emitting device characterized by comprising: The high resistance surface is formed by ion implantation from a surface of the p layer into a region where the high resistance surface is formed, or by plasma treatment of the region. Group III nitride compound semiconductor light emitting device. The linear portion of the n-contact electrode, III nitride compound semiconductor light emitting according to claim 1 or claim 2 width of the inner line portion being less than the width of the outer peripheral line section element. Each portion of the linear portion of the n-contact electrode, when the spacing between the parallel-arranged other portions of the line portion L, and the thickness of the n-layer was placed and t, 10 ≦ L / t ≦ 4. The group III nitride compound semiconductor light-emitting device according to claim 1 , wherein the group III nitride compound semiconductor light-emitting device is disposed at a position where 80 is satisfied. The portion in ohmic contact with the n layer of the large area portion is a strip shape having a width or a bent strip shape, and the width is equal to or more than the width of the outer peripheral line portion of the n contact electrode. The group III nitride compound semiconductor light-emitting device according to claim 1 , wherein the light-emitting element is not more than double.   6. The group III nitride compound semiconductor light-emitting element according to claim 1, wherein the rectangular shape of the outer peripheral line portion is a parallelogram, a rhombus, a rectangle, or a square. . The planar shape of the n contact electrode is point symmetric with respect to the center of gravity of the planar shape of the n layer, or two vertices of the rectangular n layer where the two large area portions are not provided. group III nitride-based compound semiconductor light-emitting device according to any one of claims 1 to 6, characterized in that a line symmetry with respect to a line segment connecting. Among the electrically conductive material formed between the conductive support substrate and the p layer, at least one layer in any one of claims 1 to 7, characterized in that a solder layer The Group III nitride compound semiconductor light-emitting device described. After forming at least the n layer on the epitaxial growth substrate made of a different substrate, the p layer is formed, joined to the conductive support substrate through at least the solder layer, and then the epitaxial growth substrate is removed by laser lift-off. 9. The group III nitride compound semiconductor light-emitting device according to claim 8 , wherein An outer peripheral side surface of the n layer and the p layer to claim 8 or claim 9, characterized in that from the n layer side is the light extraction side is an inclined surface of the forward taper extending to the p layer side The Group III nitride compound semiconductor light-emitting device described.

Images