JPH065906A - Manufacture of monolithic photo-coupler - Google Patents

Abstract

PURPOSE:To simplify manufacturing processes and mounting manhours of both light emitting and receiving elements. CONSTITUTION:A recessed part 22 is provided in a semiconductor substrate 21 to be a base, and photo-coupling elements 10 are formed together by an epitaxial growth. Thereafter, the photo-coupling elements 10 are divided into a light emitting element 11 and a light receiving element 12 by using a photolithography method and an etching method. The respective electrodes 31, 32 of the light emitting and receiving elements 11, 12 are formed on an identical plane, and conductive bumps 47 are formed, and thereby, the connections of the elements 11, 12 are facilitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a monolithic optical coupling device of the light receiving and emitting type.

[0002]

2. Description of the Related Art FIGS. 7 and 8 show the structure of an optical coupling device (photocoupler) manufactured by a conventional technique. FIG. 7 is a perspective view and FIG. 8 is a sectional view.

As shown in the figure, the light emitting element 3 (LED chip) and the light receiving element 4 (photodiode chip or phototransistor chip) are die-bonded to the tip of the iron-based or copper-based metal lead frames 1 and 2, respectively. Connections such as Au wires are made, and they are arranged opposite to each other. Then, the light emitting and receiving elements 3 and 4 are subjected to a primary molding with a translucent insulating material 5 for the purpose of protecting these chips and improving the photon efficiency, and then protect the lead frames 1 and 2 and shield against external light. Therefore, the light-shielding resin 6 is secondarily molded.

[0004]

In the optical coupling device manufactured by the conventional technique, the light emitting element 3 is a GaAs semiconductor and the light receiving element 4 is a Si semiconductor. , 4 had to be manufactured in a separate process.

Due to the structure of the optical coupling device, it is necessary to mount one or more light emitting element 3 and one or more light receiving element 4, respectively, on a total of two or more lead frames 1, 2. Therefore,
In the conventional technical method, the number of manufacturing steps for mounting the individual elements 3 and 4 is large, and the width between the elements 3 and 4 also varies.

Further, when considering the miniaturization of the optical coupling device, it is necessary to consider the reliability of the bonding wire connecting the light emitting / receiving elements 3 and 4 and the mounting substrate. It was unavoidable to set the wire bonding pad for electrical connection.

Further, due to the difference in the expansion coefficient between the lead frames 1 and 2 and the light-shielding resin 6 as the exterior molding resin, there is included an unstable element relating to the adhesion between the two materials.

In view of the above problems, the present invention simplifies the manufacturing process and the mounting man-hours of both the light receiving and emitting elements, reduces the variation in the width between the elements, facilitates the connection to the mounting board, and reduces the space between the members. It is an object of the present invention to provide a method for manufacturing a monolithic optical coupling device that eliminates the need to consider the difference in expansion coefficient between the two.

[0009]

The means for solving the problems according to claim 1 of the present invention is to provide an electrode of a semiconductor substrate 21 in a method of manufacturing an optical coupling device having a light emitting element 11 and a light receiving element 12, as shown in FIGS. A recess 22 is formed on the formation surface or the surface opposite to the formation surface, and the light-emitting element 11 and the optical coupling element 10 as the light-receiving element 12 are integrally formed on the surface of the recess 22 at the same time by an epitaxial growth method. Alternatively, a groove 26 is formed on the surface on the opposite side so as to cut out a part between the light emitting / receiving elements 11 and 12, and the groove 26 is filled with a translucent insulating material 27 to form an optical path to emit light. A portion other than the translucent insulating material 27 between the element 11 and the light receiving element 12 is removed by etching to electrically separate the light receiving and emitting areas, and an electrode 31 for connecting to an external circuit is provided on the electrode forming surface. Patterning 32 It is.

According to a second aspect of the present invention, a problem-solving means is to form a conductive bump 47 on each of the connection electrodes 31 and 32 according to the first aspect for mounting directly on a mounting substrate.

According to a third aspect of the present invention, a resin case 41 having an accommodating recess 42 on the upper surface is molded by injection molding or transfer molding, and the accommodating recess 42 extends from the side surface or the lower surface of the resin case 41.
The thin-film three-dimensional wiring portions 43a to 43d are three-dimensionally drawn and formed, the optical coupling element 10 according to claim 1 is mounted in the storage recess 42, and the storage recess 42 is sealed with a sealing resin 48. It is a thing.

[0012]

In the means for solving the problems according to claim 1, the light emitting element 11 and the light receiving element 12 are formed on the same semiconductor substrate 21.
Since it is formed monolithically as described above, it is possible to integrally manufacture what was conventionally manufactured in separate steps in the same step, and to simplify the steps. Further, the light emitting / receiving element 11,
The distance between 12 can be made highly precise and short distance. Therefore, it is possible to improve the light utilization efficiency.

Further, since the electrodes which have been formed separately on the upper and lower parts of the chip can be formed on the same plane, the connection between the optical coupling element 10 and the resin case 41 or the external mounting substrate is planar. Can be done to
By bumping the electrodes 31 and 32 as in claim 2, it is possible to improve the connection using a conventionally used Au wire or the like, and eliminate the occurrence of defects such as wire disconnection. Product reliability is improved.

According to the third aspect of the present invention, by using the resin case 41 having the three-dimensional wiring, the peeling and cracking of the exterior molding resin due to the difference in the thermal expansion coefficient between the conventional metal lead frame and the molding resin can be prevented. Can be prevented. In addition, the leadless structure eliminates bending and deformation of the metal lead pin.

Alternatively, the monolithic type optical coupling element 10 obtained by the manufacturing method according to claims 1 and 2 can be directly mounted on a printed circuit board having electric circuit wiring and the like. High density mounting is possible.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 is a drawing showing each manufacturing process of a monolithic optical coupling device showing a first embodiment of the present invention. FIG. 1A is a view showing a state in which a recess is formed in a semiconductor substrate. , (B) is a view in which a semiconductor growth layer is epitaxially grown in a recess, (C) is a view in which a central portion of the semiconductor growth layer is removed to form a groove, and (D) is filled with a translucent insulating material. FIG. 2, (E) is a view in which the recess is covered with a light reflecting film, (F) is a view in which it is mounted in a resin case, FIG. 2 is an external perspective view of a monolithic optical coupling device, and FIG. 3 is a first embodiment of the present invention. A resin case equipped with the monolithic optical coupling device of
(A) is a plan view, (B) is a sectional view taken along line AA of (A),
(C) is a side view, (D) is a BB cross-sectional view of (A),
(E) is a front view, (F) is a bottom view, and FIG. 4 is an external perspective view in which an optical coupling element is directly mounted on an external mounting substrate.

As shown in the figure, the optical coupling device of this embodiment receives light from a light emitting element 11 which is driven and emitted by an input power source by a light receiving element 12 and photoelectrically converts it into an electric signal for output. The two elements 11 and 12 are monolithically grown and formed as an integrated optical coupling element 10.

The optical coupling element 10 is manufactured as follows.

First, as shown in FIG. 1A, for example, GaA
A part of the surface of the semiconductor substrate 21 made of s is etched into a mesa shape by using a photolithography method and a selective etching solution to form a recess 22. The width and depth of the recess 22 are defined by the sizes of the two elements 11 and 12 to be formed.

Next, as shown in FIG. 1 (B), on the surface of the semiconductor substrate 21 including the recess 22, by epitaxial growth, P-type cladding layer _{(P-Ga 1-y Al} y As) 23, P
-Type active layer _{(P-Ga 1-x Al} x As) are successively grown to 24 and N-type cladding layer _{(N-Ga 1-y Al} y As) 25. Here, x and y in the chemical formula have a relation of x> y.

Then, each of the semiconductor growth layers 23 to 25 is subjected to ion beam etching, chemical etching, polishing or the like to remove it until the convex surface portion of the semiconductor substrate 21 is exposed. In this way, the semiconductor growth layers 23 to 25
Is limited to the inside of the recess 22.

As shown in FIG. 1C, the semiconductor substrate 21
In the central portion of the semiconductor growth layers 23 to 25 in the recess 22 of
The surface groove 2 is formed by using the photolithography method and the etching method.
6 is formed, and the light emitting element 11 and the light receiving element 12 are separated.
At this time, it is removed until the concave portion 22 of the semiconductor substrate 21 is exposed.

As shown in FIG. 1D, in order to secure an optical path between the light emitting element 11 and the light receiving element 12, SiO _{2 is provided in the} front groove 26.
A transparent insulating material 27 such as the above is filled by using a technique such as sputtering, vapor deposition, or P-CVD. The translucent insulating material 27 may be any material as long as it transmits the wavelength of light actually used for optical coupling.
It may be formed using a resin material such as polyimide.

After that, a part of the back surface of the semiconductor substrate 21 opposite to the side where the translucent insulating material 27 is formed is etched into a mesa shape by using a photolithography method and a selective etching solution,
The back groove 28 is formed. At this time, the translucent insulating material 27 is completely exposed when viewed from the back side. As a result, the light emitting element 11 and the light receiving element 12 are completely electrically separated in the optical coupling element.

Further, as shown in FIG. 1E, in order to prevent light from leaking from the exposed semiconductor growth layers 23 to 25 and the translucent insulating material 27 and improve the light utilization efficiency, the semiconductor growth layer 23 is formed. ~ 25 and Al on the surface of the translucent insulating material 27
A light reflecting film 29 such as ₂ O _{3 is formed} by an EB vapor deposition method or the like.

Next, a part of the light reflecting film 29 is etched to form electrodes 31 and 32 for electrical connection with an external circuit.

In forming the electrodes 31 and 32, AuGe / Ni, for example, is formed as the N electrode 31 by a method such as sputtering. As the P electrode 32, for example, Au / Zn is similarly formed by using a method such as sputtering. At this time, both the P and N electrodes 31 and 32 act as a light absorbing layer, so the size is made as small as possible, and preferably the minimum shape capable of bonding is set.
Further, conductive bumps 47 of Au or the like are formed on the connection electrodes 31 and 32 in order to facilitate an external connection work.

Thereafter, the optical coupling element 10 is divided into individual chips by a scribing method or dicing.

Then, as shown in FIG. 1F, the optical coupling element 10 is housed in a resin case 41.

The resin case 41 is shown in FIGS.
Molded Interco for obtaining small and thin integrated parts without using lead frame
The injection device method (hereinafter referred to as the MID method) is used. Here, the MID method is a method in which a molded product obtained by injection molding, transfer molding, or the like is formed with a frameless electric circuit by a method such as chemical plating.

A thermosetting resin or a thermoplastic resin is used as a basic material of the resin case 41. When the thermosetting resin is used, a transfer molding method or the like, and when a thermoplastic resin is used, an injection molding method or the like is used. Using a method, it is integrally formed into a multi-piece substrate shape, and after chip mounting / sealing, it is divided into individual units using a scribing method or a dicing method.

A housing recess 42 for housing the optical coupling element 10 is formed on the upper surface of the resin case 41. In the storage recess 42, thin-film three-dimensional wiring portions 43a to 43d are three-dimensionally formed by metal plating technology, sputtering technology, vapor deposition technology, or the like. Each of the three-dimensional wiring portions 43a to 43d is as shown in FIGS.
Land portions 44a for connecting to the optical coupling element 10-
44d, and the resin case 41 from the bottom of the storage recess 42.
Through the through holes 45 on the upper surface and the side surface thereof to the back surface electrodes 46a to 46d, respectively. The back surface electrodes 46a to 46d are used as soldering pads at the time of mounting on another mounting board or the like.

The monolithic optical coupling element 10 has a three-dimensional wiring portion 43a-4 in a storage recess 42 of a resin case 41.
The land portions 44a to 44d of 3d are directly mounted via the conductive bumps 47 and the like.

After mounting the optical coupling element 10 in the housing recess 42, it is resin-sealed with a light-shielding sealing resin 48 such as a black epoxy resin.

As described above, in the monolithic type optical coupling device according to this embodiment, the MID method, that is, the three-dimensional wiring portions 43a to 43d of the resin case 41 are formed by the metal plating technique, the sputtering technique, the vapor deposition technique, or the like. Since the structure is lead frame-less, it is not necessary to consider the difference in thermal expansion coefficient between the metal lead frame and the molding resin material. Therefore, peeling between the metal lead frame and the sealing resin, which has occurred conventionally, does not occur. Furthermore, since the lead frame is not used, bending and deformation of the metal lead pin are eliminated.

Further, in this embodiment, the optical coupling element 1 is used.
A light-shielding sealing resin 48 is used for 0 sealing. Therefore, it is not necessary to consider the light-shielding property as the exterior resin case 41, and it suffices to select it in consideration of only heat resistance and moisture resistance. On the contrary, by forming the light-shielding sealing resin 48 and the resin case 41 from the light-shielding resin of the same material, it is possible to prevent peeling and the like due to poor adhesion when different materials are used.

Further, as shown in FIG. 4, the optical coupling element 10 can be directly mounted on various boards such as the printed board 51 as a normal so-called surface mount type (SMT) chip component. . In this case, the light coupling sealing resin 52 is potted after the optical coupling element 10 is die-bonded using Au bumps or the like to shield the optical coupling element 10 from ambient light.

In this way, the monolithic optical coupling element can be directly mounted on the printed circuit board 51 as a bare chip component without using a resin case, so that high density mounting of the printed circuit board 51 or the like can be realized. .

(Second Embodiment) FIG. 5 is a manufacturing process drawing of a monolithic optical coupling device showing a second embodiment of the present invention. FIG. 5A is a view showing a state in which a recess is formed in a semiconductor substrate. (B) is a diagram in which a semiconductor growth layer is epitaxially grown in the recess, (C) is a diagram in which a groove is formed on the back surface of the semiconductor substrate, and (D) is a groove in which a translucent insulating material is filled, and the recess is formed by a light reflecting film. 6A and 6B show a resin case in which the monolithic optical coupling device according to the second embodiment of the present invention is mounted.
Is a plan view, (B) is a sectional view taken along line CC of (A), (C) is a side view, (D) is a sectional view taken along line DD of (A), (E) is a front view, and (F) is (F). It is a bottom view.

As shown in the figure, in the optical coupling device of this embodiment, the concave portions for forming the semiconductor growth layers 23 to 25 are separately formed in advance on the light emitting side and the light receiving side respectively, and both concave portions 22a, 2 are formed.
The optical path between 2b is formed from the back side of the semiconductor substrate 21.

The optical coupling element 10 of this embodiment is manufactured as follows.

First, as shown in FIG. 5A, the semiconductor substrate 21
A part of the surface of each of the recesses 2 is etched into a mesa shape by using a photolithography method and a selective etching solution.
2a and 22b are formed side by side. The recesses 22a, 22b
The width and depth of the element are defined by the sizes of the elements 11 and 12 to be formed.

Next, as shown in FIG. 5B, the recesses 22a, 2a
On the surface of the semiconductor substrate 21 including the 2b, by epitaxial growth, P-type cladding layer _{(P-Ga 1-y Al} y A
s) 23, P-type active layer _{(P-Ga 1-x Al} x As) are sequentially stacked and grown to 24 and N-type cladding layer _{(N-Ga 1-y Al} y As) 25 (x> y).

The portions of the semiconductor growth layers 23 to 25 protruding from the semiconductor substrate 21 are removed by ion beam etching, chemical etching or polishing.

Then, as shown in FIG. 5C, the semiconductor substrate 2
A back groove 26 is formed on a part of the back surface of No. 1 by using a photolithography method and a selective etching solution in a mesa type. At this time, the back groove 26 is formed at a position between the concave portions 22a and 22b of the semiconductor substrate 21, that is, a position corresponding to a portion where the semiconductor growth layers 23 to 25 are not formed. The position of the bottom surface of Uramizo 26 etched until sufficiently deeper than the bottom surface portion of the N-type cladding layer _{(N-Ga 1-y Al} y As) 25.

In the back groove 26 formed in the above process, as shown in FIG.
As shown in (D), in order to secure the optical path between the light receiving and light emitting elements, S
The translucent insulating material 27 such as iO ₂ is formed by using a technique such as sputtering, vapor deposition or P-CDV. Forming region, at least P-type cladding layer _{(P-Ga 1-y Al} y A
s) Laminate until 23 is completely hidden. The translucent insulating material 27 may be any material that transmits the wavelength of light actually used, and may be formed using, for example, a resin material such as polyimide.

Next, the surface of the semiconductor substrate 21 is polished until the front side of the semiconductor substrate 21 (21a in FIG. 5C) disappears. As a result, the light emitting side and the light receiving side of the semiconductor growth layers 23 to 25 are electrically completely separated.

Further, as shown in FIG. 5D, in order to prevent light from leaking from the semiconductor growth layers 23 to 25 and the translucent insulating material 27 which are exposed by an etching method or the like, the purpose is to improve the light utilization efficiency. As a light reflection film 29 of Al ₂ O ₃ or the like,
A film is formed by the B vapor deposition method or the like.

Next, a part of the light reflection film 29 is etched to form electrodes 31 and 32 for electrical connection between the element parts for receiving and emitting light and an external circuit.

In forming the electrodes 31 and 32, for example, AuGe / Ni is formed as the N electrode 31 by a method such as sputtering. As the P electrode 32, for example, Au /
Similarly, Zn is formed using a technique such as sputtering. At this time, since both the P and N electrodes 31 and 32 act as an absorption layer, it is necessary to make the electrode size as small as possible and preferably to have a minimum shape that allows bonding.

Finally, this substrate is divided and formed into individual chips from the substrate by a scribing method or dicing.

Then, the optical coupling element 10 of this embodiment is housed in, for example, the resin case 41 shown in FIGS. 6A to 6F, and the optical coupling device is completed. The resin case 41 is made by the MID method as in the first embodiment.

It goes without saying that the optical coupling device according to this embodiment also has the same effects as those of the first embodiment.

The present invention is not limited to the above embodiment, and it goes without saying that many modifications and changes can be made to the above embodiment within the scope of the present invention.

[0055]

As is apparent from the above description, according to claim 1 of the present invention, since the light emitting and receiving elements are integrally formed on the same semiconductor substrate, the manufacturing process is simpler than that of the conventional optical coupling device. It can be manufactured accurately in a short time. Further, since the distance between the light emitting and receiving elements can be shortened, the light utilization efficiency is improved, and high efficiency and low current can be expected.

According to the second aspect, by providing the conductive bumps on the electrodes, the optical coupling element can be directly bonded directly to the land portion in the resin case or a wiring circuit such as a printed circuit board. Therefore, it seems that it was used conventionally,
Since bonding with Au wire etc. is unnecessary,
It is possible to provide a highly reliable product that is not affected by the stress of the resin used for chip protection or the like and has no defects such as wire breakage. Further, since it is not necessary to provide the secondary side wire bonding pad on the external wiring circuit which has been conventionally used, the case size can be made compact. Furthermore, by designing the electrode pad so that tension is evenly applied to the chip surface,
It is also possible to prevent the Manhattan (lifting) phenomenon during die bonding. Further, by mounting the optical coupling element directly on the printed wiring board or the like, higher density mounting can be achieved as compared with the conventional one.

According to the third aspect of the present invention, by encapsulating the chip with a lead frameless resin case, cracks and peeling due to a difference in thermal expansion coefficient between the lead frame and the exterior molding resin material can be achieved. Also, the reliability problem related to the adhesion between both materials is solved. Further, the leadless structure has an excellent effect of eliminating the bending and deformation of the metal lead pin.

[Brief description of drawings]

1A and 1B are each a manufacturing process drawing of a monolithic optical coupling device showing a first embodiment of the present invention, FIG. 1A is a view showing a state in which a recess is formed in a semiconductor substrate, and FIG. 1B is a semiconductor growth in the recess. The layer is epitaxially grown, (C) is a figure in which a central portion of the semiconductor growth layer is removed to form a groove, (D) is a figure in which the groove is filled with a translucent insulating material, and (E) is a case where the concave portion is exposed to light. Figure closed with a reflective film, (F) figure mounted in a resin case

FIG. 2 is an external perspective view of a monolithic optical coupling device.

FIG. 3 is a resin case in which the monolithic optical coupling device of the first embodiment of the present invention is mounted, (A) is a plan view,
(B) is a sectional view taken along line AA of (A), (C) is a side view,
(D) is a sectional view taken along line BB of (A), (E) is a front view,
(F) is a bottom view

FIG. 4 is an external perspective view of an optical coupling element directly mounted on an external mounting substrate.

5A and 5B are each a manufacturing process drawing of a monolithic optical coupling device showing a second embodiment of the present invention, FIG. 5A showing a state in which a recess is formed in a semiconductor substrate, and FIG. 5B showing semiconductor growth in the recess. Figure in which the layer is epitaxially grown, Figure in (C) shows a groove formed on the back surface of the semiconductor substrate, and (D) in which the groove is filled with a translucent insulating material and the recess is closed by a light reflecting film.

FIG. 6 is a resin case on which the monolithic optical coupling device of the second embodiment of the present invention is mounted, (A) is a plan view,
(B) is a cross-sectional view taken along line CC of (A), (C) is a side view,
(D) is a sectional view taken along the line D-D of (A), (E) is a front view,
(F) is a bottom view

FIG. 7 is a perspective view of a conventional optical coupling device.

FIG. 8 is a sectional view of a conventional optical coupling device.

[Explanation of reference numerals] 10 optical coupling element 11 light emitting element 12 light receiving element 21 semiconductor substrate 22 recessed portion 26 groove 27 translucent insulating material 31, 32 connection electrode 41 resin case 42 accommodating recessed portion 43a to 43d three-dimensional wiring portion 47 conductive bump 48 Sealing resin

Claims (3)

[Claims] 1. A method of manufacturing an optical coupling device having a light emitting element and a light receiving element, wherein a recess is formed on a surface of a semiconductor substrate on which an electrode is formed or a surface opposite to the surface, and a recess is formed on the surface of the recess.
A light-emitting element and an optical coupling element as a light-receiving element are integrally formed at the same time by an epitaxial growth method, and a groove is formed on the electrode forming surface or a surface opposite to the electrode-forming surface so as to cut out a part between the light-receiving and emitting elements. An optical path is formed by filling the groove with a light-transmissive insulating material, and a portion other than the light-transmissive insulating material between the light emitting element and the light receiving element is removed by etching to electrically separate the light receiving and emitting light, A method for manufacturing a monolithic optical coupling device, characterized in that an electrode for connection to an external circuit is patterned on the electrode formation surface. 2. A method for manufacturing a monolithic optical coupling device, wherein conductive bumps for directly mounting on a mounting substrate are formed on each of the connection electrodes according to claim 1. 3. A resin case having an accommodating recess on the upper surface is formed by injection molding or transfer molding, and a thin film three-dimensional wiring portion is three-dimensionally drawn from the accommodating recess to the side surface or the lower surface of the resin case. Then, a method for manufacturing a monolithic optical coupling device, wherein the optical coupling element according to claim 1 is mounted in the storage recess, and the storage recess is sealed with a sealing resin.