JPH11289106A - Led array, manufacture thereof, and led printer head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the dark emission or no emission of light at a light emitter, due to the p-n short circuit caused by the crack or bonding wire contact. SOLUTION: This LED array 1 comprises an n-type semiconductor substrate 10 having a plurality of p-type light-emitting regions 11 and notches H1-H4 and individual electrodes 12 contacted separately to the emitting regions 11 with wires bonded thereto. Notches H1-H4 are formed at the surface periphery of the semiconductor substrate 10, the end sides h1-h4 of the notches H1-H4 at the substrate side faces S1-S4 are formed at positions deeper than the bottom of the emitting regions 11 in a plane involving the substrate surface to form the outermost shape of the LED array 1, as seen from the substrate surface. When the plurality of LED arrays 1 are mounted on LED print heads, the end sides h1, h2 provide contact parts, and the wires pass above the notch H4 to connect to pads outside the arrays.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a structure and a manufacturing method of an LED array in which a plurality of D (light emitting diodes) are formed, and an LED print head provided with a plurality of LED arrays and used as an exposure light source of a photosensitive drum in an electrophotographic printer or the like.

[0002]

2. Description of the Related Art FIGS. 13A and 13B are structural views of a conventional LED array, wherein FIG. 13A is a top view, and FIG.
FIG. 3C is a cross-sectional view taken along line A ′, and FIG. 3C is a cross-sectional view taken along line BB ′ in FIG. The LED array 101 in FIG. 13 includes an n-type semiconductor substrate 110, an insulating film (not shown) having a plurality of openings formed therein, a plurality of p-type semiconductor regions (light emitting portions) 11,
It has a plurality of individual electrodes 12 and a common electrode 13.

The light emitting section 11 is formed in a partial region of the semiconductor substrate 110 corresponding to the position of the opening. The individual electrode 12 is formed so that a part thereof contacts a partial region of the light emitting unit 11. The common electrode 13 is formed on the back surface of the semiconductor substrate 110 and is in contact therewith. In the LED array 101, a plurality of light emitting units 11 and a plurality of individual electrodes 12 are formed in a line. One light emitting section 11, the individual electrode 12 that contacts the light emitting section 11, the semiconductor substrate 10, and the common electrode 13 constitute one LED.

In a dicing process which is a manufacturing process of an LED array, a plurality of LED arrays formed on a semiconductor wafer have an inverted trapezoidal cross section of a semiconductor substrate 110 as disclosed in, for example, Japanese Patent Application Laid-Open No. 2-10879. In other words, the semiconductor substrate 110 on which the light emitting portion 11 is formed has a trapezoidal shape in which the front surface is the base and the back surface of the semiconductor substrate 110 on which the common electrode 13 is formed is a trapezoid. It is.

[0005] As shown in FIG. 13A, the outermost shape of the LED array 101 (semiconductor substrate 110) viewed from the upper surface (front surface) is a rectangle. However, the shape may not be rectangular due to the positioning error in the above dicing process. In the following description, the side surface of the semiconductor substrate 110 on the short dimension side perpendicular to the row of the light emitting units 11 is referred to as a short side surface,
In addition, the semiconductor substrate 11 on the long dimension side along the row of the light emitting units 11
The side of 0 is called the long side.

A device using an LED array, for example, an LED
In the print head, the common electrodes 13 on the back surface of the LED array 101 are die-bonded to the common electrode pads on the wiring board, so that the short sides face each other, the LED arrays are brought close to each other, and a plurality of LED arrays are wired. The individual electrodes 12 and the individual electrode pads on the wiring board are mounted on the substrate in a line, and connected by wire bonding. For this reason, the LED array 101 is cut out from the semiconductor wafer so that the cross section of the LED array 101 becomes an inverted trapezoid so as to be easily mounted.

[0007]

However, in the above-mentioned conventional LED array and LED print head, as shown in FIG. 14 ((b) is a cross-sectional view taken along line AA 'in FIG. When the arrays come into contact with each other, the edges on the surface on which the light emitting portion 11 is formed and the short side come into contact with each other, cracks are generated starting from this edge, and the cracks reach the light emitting portion 11. It is easy to cause dark light emission (a phenomenon in which light is emitted without applying a voltage between the electrodes) and non-lighting (a phenomenon in which no light is emitted even when a voltage is applied between the electrodes) of the light emitting unit 11 due to cracks. There was a problem.

Further, the above-mentioned conventional LED array and LE
In the case of the D print head, FIG.
(A cross-sectional view taken along the line BB ′ in FIG. 1), the size of the
When the distance between the mounting position of the LED array 101 and the position of the individual electrode pad 42 cannot be kept,
The bending margin of the wire 41 connecting the second electrode 2 and the individual electrode pad 42 is reduced, and the wire 41 comes into contact with the surface of the semiconductor substrate 110 and the side edge of the long side surface, so that the n-type semiconductor substrate 110 and the p-type semiconductor There is a problem that the area (light emitting portion) 11 may be short-circuited to cause dark emission and non-lighting of the light emitting portion 11. In particular, as shown by the dotted line in FIG. 15A, when the LED array 101 whose outermost shape is not rectangular is used, or when the LED array 101 is mounted obliquely with respect to the row of the individual electrode pads 42, Shorts were easy to occur.

FIG. 16 is a diagram showing the light emission intensity distribution of the conventional LED print head. As shown in FIG. 16, in the conventional LED print head, the joint of the LED array 101, that is, the LED array 101 Light leakage occurs from the portion near the light emitting portion 11 on the outer peripheral edge of the surface,
There has been a problem that the optical writing resolution of the light leaking portion to the photosensitive drum of the printer may be reduced.

The present invention has been made to solve such a conventional problem, and an LED array capable of eliminating dark light emission and non-lighting of a light emitting portion due to a pn short circuit due to a crack or contact of a bonding wire. And an LED print head. In addition, L which can eliminate light leakage
It is an object to provide an ED array and an LED print head.

[0011]

In order to achieve the above object, an LED array according to the present invention has a plurality of light emitting portions of a second conductivity type formed in a line in a region including a surface of a semiconductor substrate of a first conductivity type. In the above-described LED array, a notch is provided at an edge portion between the surface and the side surface of the substrate.

In order to eliminate the occurrence of cracks, the side edge of the side notch is formed at a position deeper than the bottom of the light emitting portion with respect to a plane including the surface of the substrate, and the notch is formed on the surface of the substrate. It is formed on the outer peripheral portion, or on the edge of the substrate surface and both side surfaces of the substrate perpendicular to the light emitting portion row. Also, pn
In order to eliminate the short circuit, the notch of the LED array, in which a plurality of individual electrodes individually contacting the light emitting unit are formed on the substrate surface along the light emitting unit row, is formed on the outer peripheral portion of the substrate surface or the light emitting surface. It is formed on the side edge of both sides of the substrate along the row.

The method of manufacturing an LED array according to the present invention further comprises a step of forming a groove having a substantially arc-shaped cross section by photolithography and etching in an LED array boundary region on a surface of a semiconductor wafer on which a plurality of LED arrays are formed; Leaving the groove at both ends of the region, and cutting the wafer along the groove so that the cutting side forms an obtuse angle with respect to the back surface of the wafer, and separating the LED array. Things.

According to another method of manufacturing an LED array of the present invention, a first groove having a substantially V-shaped cross section is formed by photolithography and wet etching in an LED array boundary region on a surface of a semiconductor wafer on which a plurality of LED arrays are formed. Forming a second groove having a depth close to the first groove in a rear surface region of the wafer facing the first groove; and forming the first groove in the wafer. Cleaving along the scribe line, which is the line at the bottom of the groove, to reach the second groove, and separating the LED array.

Further, an LED print head according to the present invention in which light leakage is eliminated includes a plurality of LED arrays of the present invention, and a wiring board on which the plurality of LED arrays are mounted. The notch of the LED array is filled with a translucent resin having a higher refractive index than air.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment FIG. 1 is a structural view of an LED array according to a first embodiment of the present invention, wherein (a) is a top view and (b) is A in (a).
FIG. 3C is a cross-sectional view taken along a line BB ′ in FIG. The LED array 1 of FIG. 1 includes an n-type semiconductor substrate 10, an insulating film (not shown) in which a plurality of openings exposing the semiconductor substrate 10 are formed, a plurality of p-type semiconductor regions (light emitting portions) 11, and a plurality of It has an individual electrode 12, a common electrode 13, and notches H1, H2, H3, and H4.
Note that the semiconductor substrate 10 is a p-type semiconductor and the light emitting unit 11
May be an n-type semiconductor. In the following description, the side surface on the short dimension side (the side surface perpendicular to the row of the light emitting units 11) of the semiconductor substrate 10 in the top view (a) is referred to as a short side surface,
The long side surface of the semiconductor substrate 10 (the side surface along the row of the light emitting units 11) is referred to as a long side surface.

As the semiconductor substrate 10, for example, a GaAs or GaAsP compound semiconductor is used. The p-type semiconductor region 11 is formed by diffusing a p-type impurity such as zinc into the semiconductor substrate 10 through the opening of the insulating film by using, for example, a vapor phase diffusion method or a solid phase diffusion method.
Is formed in a partial region including the surface of the opening. Also,
The individual electrodes 12 are formed on the insulating film so as to partially overlap the partial region of the light emitting unit 11, and are individually in ohmic contact with the light emitting unit 11. For the individual electrode 12, for example, aluminum or an aluminum alloy is used. Also, the common electrode 13
Are formed on the back surface of the semiconductor substrate 10 and
Ohmic contact. The common electrode 13 includes
For example, a metal containing gold such as a gold alloy is used.

In the LED array 1, a plurality of p-type semiconductor regions 11 and a plurality of individual electrodes 12 are formed in a line. One p-type semiconductor region 11, the individual electrode 12 contacting the p-type semiconductor region 11, the semiconductor substrate 10, and the common electrode 13 constitute one LED. Individual electrode 1
Reference numeral 2 is for individually supplying current to the LEDs.

The notches H1 to H4 are formed on the outer peripheral portion of the surface of the semiconductor substrate 10, respectively. Notch H1
The cross section of H4 has a substantially arc shape that protrudes toward the semiconductor substrate 10 side. The notches H1 and H2 are provided at the edges of the surface of the semiconductor substrate 10 and the short side surfaces S1 and S2, respectively (FIG. 1B). And long side surfaces S3 and S4 are provided at the end sides thereof (FIG. 1 (c)). Also, the side surfaces S1 to S
Each of the angles 4 and the back surface of the semiconductor substrate 10 is an obtuse angle.

The short side notch ends h1, h2, which are the ends of the notches H1, H2 and the short sides S1, S2, and the ends of the notches H3, H4 and the long sides S3, S4. Certain long side cut end sides h3 and h4 are
It is formed at a position deeper than the bottom of the light emitting unit 11 with respect to a plane including the surface of the zero. Short side notch edge h1,
The cross section from h2 to the back surface of the semiconductor substrate 10 is an inverted trapezoid (FIG. 1 (b)), and long side cutout edges h3, h
4 to the back surface of the semiconductor substrate 10 are also inverted trapezoids (FIG. 1 (c)). Notch H1-H4 and side S1-
S4 is formed in a dicing step.

The notches H1 to H4 and the side surfaces S
The dicing process of the LED array 1 which is the process of forming 1 to S4 will be described. FIG. 2 is an explanatory view of a dicing step according to the first embodiment of the present invention. FIG. 2 (a) is a step of forming an etching groove 22 which becomes a notch H in a semiconductor wafer 21 in which an LED array 1a is formed in a grid. And
(B) and (c) separate the LED array 1a,
This is a step of forming the notch H and the side surface S. In addition,
The LED arrays 1a and 1b in the figure are the LED arrays 1 during the dicing process, and
A light emitting unit 11, an individual electrode 12, and a common electrode 13 (see FIG. 1) are formed on a mold semiconductor wafer 21.

As shown in FIG. 2A, the LED on the semiconductor wafer 21 is formed by photolithography and etching.
The boundary region (hatched region in the figure) of the array 1a is etched to form an etching groove 22 having a substantially arc-shaped (substantially U-shaped) cross section. The etching groove 22 is formed so that the bottom is deeper than the bottom of the light emitting section 11 (see FIG. 1). Note that the dicing region 23 (region surrounded by a dotted line in the figure) is a region cut out thereafter. The dicing region 23 is set inside the etching groove 22, and the width of the dicing region 23 is smaller than the width of the etching groove 22.

Next, as shown in FIG. 2B, a diamond blade 31 having a smaller blade thickness than the width of the etching groove 22 is used.
The dicing region 23 (see FIG. 2 (a)) is arranged such that the diamond blade 31 is inclined by several degrees from the vertical direction with respect to the back surface of the semiconductor wafer 21 so that the etching grooves 22 are left at both ends of the cutting region. The semiconductor wafer 21 is cut out along the line to separate the LED array 1a. As a result, the LED array 1a formed on the semiconductor wafer 21
Are separated into an LED array 1b provided with a notch H at the edge of the surface and the side. The cross section of the LED array 1b is substantially a parallelogram.

Further, as shown in FIG. 2 (c), the diamond blade 31 is arranged at an angle of several degrees in the direction opposite to that of FIG. 2 (b), and all of the cutting side surfaces form an obtuse angle with respect to the back surface of the LED array 1. Thus, the side surface (see FIG. 2B) that forms an acute angle with the back surface of the LED array 1b is cut.

By the above dicing process, notches H1 to H4 are provided at the edges of the front surface and the side surfaces S1 to S4, and the LED is formed such that each of the side surfaces S1 to S4 forms an obtuse angle with respect to the back surface.
Array 1 is completed. Side notch edge h1 to h4
(See FIG. 1) is formed at a position deeper than the bottom of the light emitting unit 11 and is the outermost shape of the LED array 1 when viewed from the surface.

FIG. 3 shows an LED according to the first embodiment of the present invention.
It is a schematic structure diagram of a print head, (a) is a top view,
(B) is a cross-sectional view between AA ′ in (a), and (c) is a cross-sectional view between BB ′ in (a). LE in FIG.
The D print head includes a plurality of LED arrays 1 (see FIG. 1), a wiring board 40, and a plurality of individual electrode pads 42.
And a plurality of wires 41 and a drive IC (not shown) for driving the LED array 1.

The wiring board 40 includes an LED array 1-k
(K is an arbitrary integer) short side S2 and LED array 1-
The plurality of LED arrays 1 are arranged close to each other and mounted such that the short side surfaces S1 of (k + 1) face each other, and the light emitting unit rows of each LED array 1 are aligned. The common electrode 13 on the back surface of the LED array 1 is die-bonded to a common electrode pad (not shown) formed at the LED array mounting position on the wiring board 40. Further, the plurality of individual electrode pads 42 are provided on the LED array 1 mounted on the wiring board 40.
Corresponding to the individual electrodes 12 of FIG.
They are formed in a line along the long side surface S4 of the ED array 1. In addition, the wire 41 is provided with the notch H of the LED array 1.
4, the corresponding individual electrode 12 and the individual electrode pad 42 are connected.

LE in the LED print head of FIG.
Surface of D array 1 and long side surface S4 on individual electrode pad 42 side
Since the notch H4 is provided at the end of the LED array, the wire 41 has a greater bending allowance than the conventional LED array, and the wire 41 contacts the n-type semiconductor substrate 10 with the light emitting unit 11. The pn short circuit of the semiconductor substrate 10 hardly occurs. Therefore, dark light emission and non-lighting due to the pn short circuit hardly occur.

FIGS. 4A and 4B are explanatory diagrams when the LED array 1 is mounted in contact with the LED array 1. FIG. 4A is a top view, and FIG. 4B is a sectional view taken along line AA 'in FIG. The outermost shape of the LED array 1 is the side cutout edge portions h1 to h1 of the cutouts H1 to H4 (see FIG. 3A), and the LED array 1-k and the LED array 1- (k + 1) are brought close to each other. In case of passing, the short side notch edge h2 of the LED array 1-k and the short side notch edge h1 of the LED array 1- (k + 1) contact each other. It occurs with the end portions h1 and h2 as starting points.
However, the short side cutout end sides h1 and h2 are the light emitting units 1
Since it is formed at a position deeper than 1, even if a crack occurs starting there, it is difficult for the crack to reach the light emitting unit 11. Therefore, even if a crack occurs due to contact, dark light emission and non-lighting hardly occur.

As described above, according to the first embodiment of the present invention, the notches H1 to H4
Is provided, the wire 41 that connects the individual electrodes 12 of the LED array 1 to the individual electrode pads 42 of the LED print head has a large bending allowance.
Pn short-circuit between the semiconductor substrate 10 and the light-emitting portion 11 due to the contact of the semiconductor substrate 10 is less likely to occur, and dark light emission and non-lighting caused by the pn short-circuit can be eliminated. Note that if only the wire bending margin is to be increased, the LED print head of FIG. 3 only needs to be provided with the notch H4 through which the wire 41 passes over the sky, and may not have the notches H1 to H3. . Further, the side notch edge portions h1 to h4 may be located between a plane including the front surface of the semiconductor substrate 10 and a plane including the back surface of the semiconductor substrate.

Further, the side cutout edges h1 to h4 are
When the LED array 1 is mounted on the LED print head, it is located at a position deeper than the bottom of the light emitting unit 11 and has the outermost shape of the LED array 1.
Even if the D arrays 1 are in contact with each other, the contact points are the short side cutout end sides h1 and h2. Therefore, even if a crack starts from the short side cutout end sides h1 and h2, the light emitting unit 11 is cracked. Is difficult to reach, and dark light emission and non-lighting caused by the occurrence of cracks can be eliminated. In addition, if it is only difficult for the crack to reach the light emitting portion 11, the short side cutout edge portions h1 and h2 serving as contact portions are provided.
Notches H1 and H2 may be provided, and notches H3 and H4 may not be provided.

Second Embodiment FIGS. 5A and 5B are structural views of an LED array according to a second embodiment of the present invention, wherein FIG. 5A is a top view, and FIG. 5B is a cross section taken along line AA ′ in FIG. FIG. 3C shows BB ′ in FIG.
It is sectional drawing between. In FIG. 5, the same components as those in FIG. 1 are denoted by the same reference numerals.

The LED array 51 shown in FIG. 5 includes an n-type semiconductor substrate 50, an insulating film (not shown) having a plurality of openings for exposing the semiconductor substrate 50, and a plurality of p-type semiconductor regions (light emitting portions) 11. , The plurality of individual electrodes 52 and the common electrode 1
3 and notches I1, I2, I3 and I4. That is, the LED 51 includes the semiconductor substrate 50 and the individual electrodes 52.
1 except for the notches I1, I2, I3 and I4.
It is the same as the ED array 1. The semiconductor substrate 50 is the same as the semiconductor substrate 10 of FIG. 1 except for the shapes of the notches I1 to I4 and the side surfaces T1, T2, T3, and T4. In addition, the plurality of individual electrodes 52 are arranged in two rows in a zigzag pattern because the plurality of light emitting units 11 are arranged at a fine pitch.

The notches I1 to I4 are formed in the outer peripheral portion of the surface of the semiconductor substrate 50, respectively. Notch I1
The cross section of I4 is a substantially straight line that is inclined so as to descend outward. The notches I1 and I2 are provided at the edges of the surface of the semiconductor substrate 50 and the short sides T1 and T2, respectively (FIG. 5B), and the notches I3 and I4 are formed on the surface of the semiconductor substrate 10. And long side surfaces T3, T4 (FIG. 5 (c)). Also, the side surface T1
The angle between T4 and the back surface of the semiconductor substrate 50 is substantially a right angle.

The short side notch edges i1 and i2, which are the edges of the notches I1 and I2 and the short sides T1 and T2, and the edges of the notches I3 and I4 and the long sides T3 and T4. One long side cutout edge part i3, i4 is formed by the semiconductor substrate 5
It is formed at a position deeper than the bottom of the light emitting unit 11 with respect to a plane including the surface of the zero. Also, the side notch edge i
1 to i4 protrude like eaves from the corresponding side surfaces T1 to T4.

The notches I1 to I4 and the side surface T
The dicing process of the LED array 51, which is the process of forming the T1 to T4, will be described. FIGS. 6A and 6B are explanatory views of a dicing step according to the second embodiment of the present invention. FIGS. 6A and 6B show a cutout I on the surface of a semiconductor wafer 61 on which an LED array 51a is formed in a grid. First groove 62
Is formed, and a second groove 63 serving as the side surface T is formed on the back surface of the semiconductor wafer 61. (b) or (c) is a step of separating the LED array 51a. The LED array 51a in the figure is the LED array 51 in the middle of the dicing process, and the light emitting unit 11 and the individual electrodes 52 are placed on the n-type semiconductor wafer 61 serving as the semiconductor substrate 50.
And a common electrode 13 (see FIG. 5).

As shown in FIGS. 6A and 6B, the boundary region (FIG. 6) of the LED array 51a on the semiconductor wafer 61 is formed by photolithography and wet etching.
The hatched area in (a) is wet-etched to form a first groove 62 having a substantially V-shaped cross section. This first groove 62
Are formed such that the bottom of the center is deeper than the bottom of the light emitting section 11 (see FIG. 5). For the above wet etching, an etchant capable of causing the etching to proceed along the plane orientation of the semiconductor wafer 61 is used. In addition,
After the formation of the second groove 63, the semiconductor wafer 61 is cleaved along a scribe line 62a that is a central valley bottom line.

Further, a diamond blade 71 having an appropriate blade thickness is used, and the diamond blade 71 is arranged perpendicular to the back surface of the semiconductor wafer 61, and the semiconductor wafer 61 below the first groove 62 formed on the surface is formed. In the back area of
A second groove 63 having a rectangular cross section is formed to a depth close to the first groove 62. The cross-sectional shape of the second groove 63 is arbitrary, and may be, for example, a trapezoid.

Next, as shown in FIG. 6C, the semiconductor wafer 61 is placed on the stage 72 with the surface on which the first groove 62 is formed facing upward, and is placed in the first groove 62 on the back surface of the heat insulating member 73. Using a cleavage tool provided with a vertically long heater protrusion 74 having a reverse semicircular cross section at a corresponding position, the heater protrusion 74 is brought into contact with the first groove 62 to form a semiconductor region forming a wall surface of the first groove 62. Is locally heated to cause thermal distortion in the semiconductor region around the scribe line 62a, which is the valley bottom line of the first groove 62, so that the semiconductor wafer 61 reaches the second groove 63 along the scribe line 62a. And the LED array 51a is separated. The heater protrusion 74 may be any as long as it can locally heat the semiconductor region around the wall surface of the first groove 62 including the scribe line 62a, and its cross-sectional shape is arbitrary, and may be, for example, V-shaped. Further, the heat insulating member 73 may be any material as long as the heat generated by the heater protrusion 74 is not released.

Alternatively, as shown in FIG.
Semiconductor wafer 61 with the surface having grooves 62 formed thereon facing upward.
Is placed on the stage 72, and the first groove 6 on the back surface of the pressing member 75 is
2, using a cleavage tool provided with a vertically long pressing protrusion 76 having an inverted semicircular cross section at the position corresponding to 2, bringing the pressing protrusion 76 into contact with the side wall of the first groove 62, By applying pressure so as to spread the side wall and causing pressure distortion in the semiconductor region around the scribe line 62a, the semiconductor wafer 61 is moved along the scribe line 62a in the second direction.
And the LED array 51a is separated. The pressing protrusion 76 may be any as long as it can apply a pressure on the side wall of the first groove 62 so as to push the first groove 62.
It is optional similarly to 4.

By the above dicing process, notches I1 to I4 are provided at the edges of the surface and the side surfaces T1 to T4, and the side notches edge portions i1 to i4 (see FIG. 5) are formed at the side surfaces T1 to T4. The LED array 51 projecting like an eave is completed. The side notch edge portions i1 to i4 are the light emitting portion 1
1 is formed at a position deeper than the bottom, and is the outermost shape of the LED array 51 when viewed from the surface. Further, the scribe line 62a formed by the first groove 62 is formed by photolithography and wet etching with high positioning accuracy, and the LED array 51a is separated along the scribe line 62a, so that the outermost shape of the LED array 51 is accurate. It becomes a rectangle.

FIG. 7 shows an LED according to a second embodiment of the present invention.
FIG. 2 is a schematic structural diagram of a print head. In FIG.
(A) is a top view, (b) is a cross-sectional view between AA ′ in (a), and (c) is a cross-sectional view between BB ′ in (a). In FIG. 7, the same components as those in FIG. 3 are denoted by the same reference numerals. The LED print head of FIG. 7 includes a plurality of LED arrays 51 (see FIG. 5), a wiring board 40,
A plurality of individual electrode pads 42, a plurality of wires 41, L
A drive IC (not shown) for driving the ED array 51 is provided.

The wiring board 40 includes an LED array 51-k
Short side T2 of the LED array 1- (k + 1)
A plurality of LED arrays 51 are arranged close to each other and mounted such that the LED arrays 51 face each other and the light emitting unit rows of each LED array 51 are aligned. Further, the plurality of individual electrode pads 42 are provided on the LED array 5 mounted on the wiring board 40.
The LED array 51 is formed in a row on the wiring board 40 along the long side surface T4 corresponding to one individual electrode 52. Further, the wire 41 passes over the notch I4 of the LED array 51 and connects the corresponding individual electrode 52 and the individual electrode pad 42.

LE in the LED print head of FIG.
The long side surface T of the surface of the D array 51 and the individual electrode pad 42 side
Since the notch I4 is provided at the end of 4,
The bending margin of the wire 41 is larger than that of the conventional LED array, and a pn short circuit between the light emitting unit 11 and the semiconductor substrate 50 due to the contact of the wire 41 with the n-type semiconductor substrate 50 is less likely to occur. Therefore, dark light emission and non-lighting due to the pn short circuit hardly occur.

The outermost shape of the LED array 51 is the cutout end faces i1 to i4 of the cutouts I1 to I4, and the LED array 51-k and the LED array 51- (k +
If 1) is too close, the short side cutout edge i2 of the LED array 51-k and the short side cutout edge i1 of the LED array 1- (k + 1) come into contact with each other. Is generated starting from the short side cutout end sides i1 and i2. However, the short side cutout edge i
Since 1 and i2 are formed at positions deeper than the light emitting section 11, even if a crack occurs starting there, it is difficult for the crack to reach the light emitting section 11. Therefore, even if a crack occurs, dark emission and non-lighting hardly occur.

In the dicing process of the first embodiment, the LED array is separated by cutting the semiconductor wafer with a diamond blade. However, the positioning accuracy of the diamond blade with respect to the semiconductor wafer is as good as that of an exposure apparatus using the photolithography method. L
The top surface of the outermost shape of the ED array may not be rectangular as shown in FIGS. 8A and 8B are explanatory diagrams in the case where the LED array 1 whose outermost shape is not rectangular is wire-bonded. FIG. 8A is a top view, FIG. 8B is a cross-sectional view taken along the line CC ′ at the left end in FIG. () Is a cross-sectional view taken along the line DD ′ at the right end in (a). FIG. 9 is an explanatory diagram in the case where the LED array 1 whose outermost shape is not rectangular is mounted.

Even when the outermost shape of the LED array 1 is not rectangular, as shown in FIG. 8, that the margin for wire bending is larger than that of the conventional LED array is the same as the case where the outermost shape is rectangular. . Further, when the contact is made, a crack is generated from the side notch end sides h1 and h2 located at a position deeper than the bottom of the light emitting unit 11, and it is difficult for the crack to reach the light emitting unit 11. It is not different from the case. However, the LED array
Normally, since the end side surfaces are mounted close to each other, unevenness of the outermost dimensions of the LED array is not preferable because it causes a decrease in mounting accuracy. Further, depending on the shape of the outermost shape, as shown in FIG.
There is a case where the side cutout edge h2 of the ED array 1-k and the side cutout edge h1 of the LED array 1- (k + 1) come into contact with each other in a manner similar to a point contact. In this case, the semiconductor substrate 10 (see FIG. 1) may be locally strongly damaged, and the size of the crack may be increased.

However, in the dicing step according to the second embodiment of the present invention, the surface of the semiconductor wafer 61 has a substantially V-shaped cross-section by photolithography and wet etching, which have high positioning accuracy with respect to the semiconductor wafer 61, and has a valley bottom. The line forms a first groove 62 that becomes a scribe line 62 a, and a second groove of a depth close to the first groove 62 is formed in a back surface region of the semiconductor wafer 61 facing the first groove 62.
By forming the groove 63 and cleaving the semiconductor wafer 61 along the scribe line 62a, it is possible to separate the LED array 51 having a rectangular shape with the highest outer shape and uniform outermost size from the semiconductor wafer 61. it can.
Therefore, it can be mounted on the wiring substrate of the LED print head with high accuracy, and the occurrence of large-scale cracks can be eliminated.

As described above, according to the second embodiment of the present invention, the notches I1 to I4 are provided in the outer peripheral portion of the surface of the LED array 51 in the same manner as in the first embodiment, so that L
Since the bending margin of the wire 41 connecting the individual electrode 52 of the ED array 51 to the individual electrode pad 42 of the LED print head is increased, a pn short circuit between the semiconductor substrate 50 and the light emitting unit 11 due to the contact of the wire 41 is less likely to occur. , Pn short-circuit, and dark emission and non-lighting can be eliminated.

Further, similar to the first embodiment, the side notch edges i1 to i4 are located at positions deeper than the bottom of the light emitting portion 11 so as to be the outermost shape of the LED array 51. When the LED array 51 is mounted on the LED print head, even if the LED arrays 51 come into contact with each other, the contact point is the short side cutout edge i1.
And i2, even if cracks occur starting from the short side cutout edge portions i1 and i2, the cracks are unlikely to reach the light emitting portion 11, and dark light emission and non-lighting caused by the cracks can be eliminated. .

Further, a first groove 62 having a substantially V-shaped cross section and a deepest valley bottom line serving as a scribe line 62a is formed on the surface of the semiconductor wafer 61 by photolithography and wet etching. Groove 6
The first groove 6 is formed in the back surface area of the semiconductor wafer 61 facing the second groove 6.
A second groove 63 having a depth close to that of the first groove 6;
2 causes thermal distortion or pressure distortion in the peripheral semiconductor region, and cleaves the semiconductor wafer 61 along the scribe line 62a, so that the LED array 5 can be cut with a diamond blade with higher accuracy than in the first embodiment.
1 can have the same outermost dimensions.

Third Embodiment FIGS. 10A and 10B are schematic structural views of an LED print head according to a third embodiment of the present invention, wherein FIG. 10A is a top view, and FIG. 10B is a view between AA ′ in FIG. FIG. 3C is a cross-sectional view taken along line BB ′ in FIG. In FIG. 10, the same components as those in FIG. 3 are denoted by the same reference numerals. FIG.
The LED print head of FIG. 1 is the same as the LED print head of FIG.
The cutouts H1 to H4 are filled with a translucent resin 81 having a refractive index higher than that of air by applying and curing a translucent resin source (liquid or semi-solid) on H4 to H4.

The translucent resin 81 is provided at the joint where the notch H2 of the LED array 1-k and the notch H1 of the LED array 1- (k + 1) are close to each other and face each other.
The resin surface 82 is formed so as to be non-parallel to the cutout surfaces of the semiconductor substrate 10 in the cutouts H1 and H2 (so that the film thickness on the cutouts H1 and H2 is not uniform). Further, the translucent resin 81 is formed so that the film thickness on the light emitting unit 11 is uniform. Here, by forming the translucent resin 81 so that the resin surface 82 becomes flat, the resin surface 82 becomes non-parallel to the cutout surfaces of the cutouts H1 and H2, and the film on the light emitting unit 11 is formed. The thickness is made uniform. Further, the translucent resin 81 is made of LE
Since it is also formed on the surface of the D array 1, it goes without saying that it is an insulating resin. As the translucent resin 81, for example, a silicon resin is used.

FIG. 11 is a view showing a resin coating process according to a third embodiment of the present invention. FIG. 11 (a) is a process example when the viscosity of a light transmitting resin source to be coated is high, and FIG. 11 (b) is a coating process. It is a process example in the case where the viscosity of the translucent resin source is low. FIG.
1A, the nozzle of the cylinder container 91 filled with the translucent resin source 81a is connected to the wiring board 40 (FIG. 10).
(See FIG. 2), the LED array 1 is mounted in close proximity to the surface of the LED array 1, and a certain amount of light-transmitting resin source 81a is supplied to the array surface from the nozzles by applying a certain pressure to the cylinder container 91. Is moved at a constant speed in the longitudinal direction of the LED array 1, and the light transmitting resin source 8 is moved.
1a is applied. Also, in FIG. 11B, the nozzle of the sprayer 92 filled with the translucent resin source 81a is set to L
While being arranged above the surface of the ED array 1 and spraying a fixed amount of the translucent resin source 81a from the nozzle onto the array surface,
The sprayer 92 is moved at a constant speed in the longitudinal direction of the LED array 1 to apply the translucent resin source 81a. In addition,
At this time, since the wire 41 has already been bonded, the translucent resin source 81a is applied so that the wire 41 does not contact the semiconductor substrate of the LED array 1.

In the resin application step shown in FIG. 11A or 11B, the light transmitting resin source 81a is applied to the surface of the LED array 1 with a uniform thickness, and the notches H1 and H
2 is filled with the translucent resin source 81a. Then, the transparent resin source 81a is cured by a curing treatment such as drying or heating. Thereby, on the surface of the LED array 1, on the joint including the notches H1 and H2, and on the notch H
3, a light-transmitting resin 81 having a flat resin surface 82 on the surface of the LED 1 and on the joint is formed on H4, and the notches H1 to H4 are filled with the light-transmitting resin 81.

Notch H4 through which wire 41 passes over the sky
Since the light-transmitting resin 81 formed thereon is an insulating resin, if the wire 41 is notched, the light-transmitting resin 8
1 does not cause a pn short circuit between the semiconductor substrate 10 and the light emitting unit 11. Therefore, it is possible to eliminate dark light emission and non-lighting of the light emitting unit 11 caused by the pn short circuit.

FIG. 12 shows an LE according to the third embodiment of the present invention.
FIG. 4 is a diagram schematically illustrating a light emission intensity distribution of a D print head. By filling the notches H1 and H2 at the joints of the LED array 1 with the translucent resin 81, the notches H1 and H2 are formed.
2. A light-transmitting resin having a refractive index different from that of air and the semiconductor substrate 10 formed such that the resin surface 82 is non-parallel to the cutout surface which is the light-emitting surface of the leak light. Since it is confined within 81, light leakage can be eliminated as shown in FIG. Therefore, it is possible to prevent a decrease in optical writing resolution at a joint portion of the LED array 1 due to light leakage.

Of the light generated by the light emitting portion 11, only light incident on the cutout surface at an incident angle within a first critical angle determined by the refractive index difference between the light transmitting resin 81 and the semiconductor substrate 10 is transmitted. Out into the conductive resin 81. On the other hand, light incident on the resin surface 82 at an incident angle within the second critical angle determined by the refractive index difference between the air and the translucent resin 81 is radiated into the air. Light incident on the resin surface 82 at an angle is reflected by the resin surface 82 and confined in the translucent resin 81. By forming the translucent resin 81 such that the resin surface 82 is non-parallel to the notch surfaces of the notches H1 and H2, leaked light emitted from the notch surfaces is confined in the translucent resin 81. be able to.

In the conventional LED array, the light emitting section 1
1 of the light generated in the semiconductor substrate 110 (see FIG. 13)
Is reflected at the side edge of the surface, and is incident on the surface edge at an incident angle within a critical angle determined by the refractive index difference between the air and the semiconductor substrate 10, and becomes light leakage. It is difficult to form a translucent resin 81 on the surface edge of the conventional LED array, the resin surface of which is not parallel to the surface edge, that is, the array surface. Is LE
Since the surface has a slope with respect to the horizontal plane including the surface of the D array 1, it is easy to form the translucent resin 81 such that the resin surface 82 is not parallel to the cutout surface.

As described above, according to the third embodiment of the present invention, the notch H of the plurality of mounted LED arrays 1 is provided.
1, H2 is filled with the translucent resin 81, and the leakage light emitted from the cutout surface is confined in the translucent resin 81, so that light leakage can be eliminated. It is possible to prevent a decrease in the optical writing resolution of the LED print head.

The notch H4 through which the wire 41 passes over the sky is filled with an insulating translucent resin 81,
Is prevented from contacting the semiconductor substrate 10,
It is possible to eliminate dark light emission and non-lighting of the light emitting unit 11 due to the pn short circuit.

In the third embodiment, the translucent resin 81 is formed on the LED array 1 of the first embodiment. However, the LED array having the cutouts I1 to I4 of the second embodiment is provided. A translucent resin 81 may be formed on 51.

In the third embodiment, the LE
The translucent resin 81 was also formed on the surface of the D array 1, but if possible, the translucent resin 81 was formed only on the notches H1 to H4.
May be formed. However, notch H1,
If the light-transmitting resin 81 is to be formed only on the H2, the light-transmitting resin 81 is also formed on the light emitting portion 11 at the array end close to the notches H1 and H2.
Since the light-emitting characteristics of the light-emitting portion 11 in which the light-transmitting resin 81 is not formed and the light-emitting portion 11 in which the light-transmitting resin 81 is not formed may vary, in the third embodiment, in order to make the light-emitting characteristics uniform, The translucent resin 81 is also formed on the surface.

[0064]

As described above, according to the present invention, L
By providing notches at the edges of the surface of the ED array and the side surface along the light emitting unit row, the degree of bending margin of the wire connecting the individual electrodes of the LED array to the individual electrode pads of the LED print head is increased. Therefore, a pn short circuit between the semiconductor substrate and the light emitting section due to the contact of the wire is less likely to occur, and there is an effect that dark light emission and no lighting caused by the pn short circuit can be eliminated.

A notch is provided at an edge between the surface of the LED array and both side surfaces perpendicular to the light emitting unit row, and a side notch which is an edge between the notch and a side surface perpendicular to the light emitting unit row. The edge is deeper than the bottom of the light emitting part,
When the LED array is mounted on the LED print head, the LED array has an outermost shape.
Even if the ED arrays come into contact with each other, the point of contact is the side notch edge, so even if a crack starts from the side notch edge, it is difficult for the crack to reach the light emitting part, and the crack is generated. There is an effect that dark light emission and non-lighting caused by the above can be eliminated.

Further, in the LED print head mounted with a plurality of the LED arrays of the present invention, wherein notches are provided at the edges of the front surface and the side surfaces along the light emitting portion row.
By filling the notch of the ED array with a translucent resin to prevent the wire from contacting the semiconductor substrate, p
There is an effect that it is possible to eliminate dark light emission and non-lighting of the light emitting unit due to n short circuit.

Further, in the LED print head in which a plurality of the LED arrays of the present invention are provided with cutouts at the side edges of the front surface and both side surfaces perpendicular to the light emitting unit row, the cutouts of the LED array are transparent. Light leakage can be eliminated by filling the light-sensitive resin and confining the leaked light emitted from the cutout surface in the light-transmitting resin, so that the light writing resolution of the LED print head caused by the leaked light can be reduced. There is an effect that the decrease in the number can be eliminated.

[Brief description of the drawings]

FIG. 1 is a structural diagram of an LED array according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a dicing step of the LED array according to the first embodiment of the present invention.

FIG. 3 is a schematic structural view of the LED print head according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram when the LED array is contacted and mounted in the LED print head according to the first embodiment of the present invention.

FIG. 5 is a structural diagram of an LED array according to a second embodiment of the present invention.

FIG. 6 is an explanatory diagram of a dicing step of an LED array according to a second embodiment of the present invention.

FIG. 7 is a schematic structural diagram of an LED print head according to a second embodiment of the present invention.

FIG. 8 is an explanatory diagram in a case where an LED array whose outermost shape is not rectangular is wire-bonded in the LED print head according to the first embodiment of the present invention.

FIG. 9 is an explanatory diagram when an LED array whose outermost shape is not rectangular is mounted in the LED print head according to the first embodiment of the present invention.

FIG. 10 is a schematic structural diagram of an LED print head according to a third embodiment of the present invention.

FIG. 11 is a view showing a resin application process of an LED print head according to a third embodiment of the present invention.

FIG. 12 is a diagram schematically showing a light emission intensity distribution of an LED print head according to a third embodiment of the present invention.

FIG. 13 is a structural diagram of a conventional LED array.

FIG. 14 shows an LED in a conventional LED print head.
FIG. 4 is an explanatory diagram when an array is mounted in contact with the array.

FIG. 15 shows an LED in a conventional LED print head.
It is explanatory drawing in the case of wire bonding an array.

FIG. 16 is a diagram schematically showing a light emission intensity distribution of a conventional LED print head.

[Explanation of symbols]

1,51 LED array, 10,50 n-type semiconductor substrate, 11 p-type semiconductor region (light emitting portion), 12,52
Individual electrode, 21, 61 semiconductor wafer, 22 etching groove, 40 wiring board, 41 bonding wire, 42 individual electrode pad, 62 first groove, 6
2a scribe line, 63 second groove, 81 translucent resin, H, I notch, h, i side notch edge, S, T side of semiconductor substrate.

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Yuko Kitayama 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd.

Claims (18)

[Claims] 1. An LED in which a plurality of light emitting units of a second conductivity type are formed in a line in a region including a surface of a semiconductor substrate of a first conductivity type.
In the array, a notch is provided at an end portion between a surface and a side surface of the substrate. 2. A side edge of a notch, which is an edge between the notch and a side surface of the substrate, has an outermost shape when viewed from a substrate surface side. L
ED array. 3. The LED array according to claim 2, wherein the side notch edge is formed at a position deeper than a bottom of the light emitting portion with respect to a plane including the substrate surface. 4. The side notch edge portion is located between a plane including a substrate front surface and a plane including a substrate back surface, and the cross section of the notch has a substantially circular arc shape protruding toward the substrate.
3. The LED array according to claim 2, wherein the LED array is inclined and substantially linear. 5. The LED array according to claim 2, wherein the side surface of the substrate forms an obtuse angle or a substantially right angle with the back surface of the substrate. 6. The LED array according to claim 5, wherein the side edge of the side cutout protrudes like an eaves with respect to the side surface of the substrate. 7. The method according to claim 1, wherein the notch is formed in an outer peripheral portion of the substrate surface or in an edge portion between the substrate surface and both side surfaces of the substrate perpendicular to the light emitting portion row. LED array. 8. The LED array according to claim 1, wherein a plurality of individual electrodes individually contacting the light emitting unit are formed on the substrate surface along the light emitting unit row, and the notch is formed on an outer peripheral portion of the substrate surface, or 2. The LED array according to claim 1, wherein the LED array is formed at an end portion between a surface of the substrate and both side surfaces of the substrate along the light emitting unit row. 9. A step of forming grooves having a substantially arc-shaped cross section by photolithography and etching in an LED array boundary region on a surface of a semiconductor wafer on which a plurality of LED arrays are formed, leaving said grooves at both ends of a cutting region; Cutting the wafer along the groove so that the cut side surface forms an obtuse angle with respect to the back surface of the wafer, and separating the LED array. 10. A step of forming a first groove having a substantially V-shaped cross section by photolithography and wet etching in an LED array boundary region on a surface of a semiconductor wafer on which a plurality of LED arrays are formed; Forming a second groove having a depth close to the first groove in a rear surface region of the opposed wafer; and forming the wafer along a scribe line that is a line at the bottom of the first groove. Cleaving to reach the second groove and separating the LED array. 11. The step of separating the LED array comprises:
The method of manufacturing an LED array according to claim 10, wherein the wafer is cleaved by applying a pressure on the side wall of the first groove so as to push the first groove. 12. The step of separating the LED array,
11. The method according to claim 10, wherein the wafer is cleaved by locally heating a semiconductor region around a wall surface of the first groove. 13. The LED array in which a plurality of light emitting units of the second conductivity type are formed in a row in a region including the surface of the wafer of the first conductivity type, and grooves are formed on the surface of the wafer. The method according to claim 9, wherein the step includes forming the groove such that a bottom of the groove is at a position deeper than a bottom of the light emitting unit with respect to a plane including a wafer surface. A method for manufacturing an LED array. 14. The plurality of LED arrays according to claim 7, wherein the plurality of LED arrays are mounted so that side surfaces of a substrate perpendicular to the light emitting unit rows face each other and each light emitting unit row is aligned. L provided with a wiring board
ED print head. 15. The plurality of LED arrays according to claim 8, a wiring board on which the plurality of LED arrays are mounted, and a wiring board corresponding to the individual electrodes of the mounted LED arrays, respectively. A plurality of individual electrode pads formed in the LED, and a wire that passes over the notch along the light emitting unit row and connects the corresponding individual electrode and the individual electrode pad. Print head. 16. The L according to claim 14, wherein a light-transmitting resin having a higher refractive index than air is filled in the notch of the mounted LED array.
ED print head. 17. The LED print head according to claim 16, wherein the translucent resin is formed so that the resin surface is not parallel to the cutout surface. 18. The LED print head according to claim 16, wherein said translucent resin is an insulating resin.