KR100590534B1 - Micro optical bench structure and method of manufacturing the same - Google Patents

Abstract

A micro optical bench structure and a method of manufacturing the same are disclosed. Disclosed is a semiconductor substrate having a uniform thickness, a light receiving element provided on the semiconductor substrate, a light emitting element provided on the semiconductor substrate at a position spaced apart from the light receiving element, and the semiconductor substrate between the light receiving element and the light emitting element. A mirror structure provided on the light reflecting light emitted from the light emitting device, and an electrode wiring formed to connect the light emitting device to an external power source, and the mirror structure has a surface facing the light emitting device at a predetermined angle. It provides a micro-optic bench structure and a method of manufacturing the inclined mirror support and a reflecting means provided on the inclined surface of the mirror support.

Description

Micro optical bench structure and method of manufacturing the same

1 is a cross-sectional view of a micro optical bench structure according to the prior art.

2 is a cross-sectional view of a micro optical bench structure according to an embodiment of the present invention.

3 to 11 are cross-sectional views illustrating a method of manufacturing the micro-optic bench structure shown in FIG.

* Description of the symbols for the main parts of the drawings *

40: substrate 42: light receiving element

44: electrode wiring 44a, 44b: first and second electrode wiring

46: solder bump 47: mold layer

48: light emitting element 50: negative photoresist layer

50a: mirror support 52: reflecting means

60: light blocking film 64: shadow mask

66: aluminum

A1: Exposed Region of Negative Photoresist Layer

M1: slope of the mirror support

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device and a method for manufacturing the same, and more particularly, to a micro optical bench structure equipped with a light emitting device such as a laser diode and a light receiving device such as a photo diode, and a method of manufacturing the same. It is about.

When writing information to a disc type optical recording medium such as a CD or a DVD, the input electrical signal is converted into a laser beam and irradiated to the optical recording medium. When reading information recorded on the optical recording medium, the laser beam reflected from the optical recording medium is detected and converted into an electrical signal.

An essential part of this information recording and reproducing process is the optical pickup device. The optical pickup device includes a laser diode, a photo diode, an optical bench, and the like. In this case, light emitting and light receiving elements such as a laser diode and a photodiode are mounted on an optical bench. Therefore, the optical bench can have a decisive influence on the miniaturization, low cost, and yield of the optical pickup device.

1 shows a structure of an optical bench structure according to the prior art.

Referring to FIG. 1, a groove 12 is formed in a region where a laser diode 18 of a silicon substrate 10 of 9.74 ° is to be mounted. The bottom part 12a of the groove 12 is formed convexly. The first electrode wiring 14 is present on the bottom portion 12a of the groove 12, and the solder bumps 16 are present on the first electrode wiring 14. The laser diode 18 is on the solder bumps 16. The groove 12 side surface around the bottom portion 12a is an inclined surface. On the side face 12b of the groove 12 facing the laser emitting surface of the laser diode 18, there is a mirror 20 which reflects upwardly the laser L emitted from the laser diode 18. The photodiode 22 is mounted around the groove 12 of the silicon substrate 10. The second electrode wiring 24 is present on the silicon substrate 10 around the photodiode 22. The second electrode wiring 24 is connected to an external power source (not shown), and is also connected to the first electrode wiring 14. Power supplied from an external power source is supplied to the laser diode 18 through the second electrode wiring 24 and the first electrode wiring 14, and the laser diode 18 emits the laser L.

The optical bench structure according to the prior art described above has the following problems.

First, it is inefficient in manufacturing optical bench structures.

In other words, it is equipped with a laser diode and a photodiode, and manufactures an optical bench in which the mirrors 20 are aligned, which requires a high level of technology, takes a lot of time, and a desired spec in terms of yield and performance. Hard to match.

More specifically, the bottom portion 12a of the optical bench on which the laser diode is mounted is formed by wet etching, where the side 12b of the groove 12 on which the mirror 20 is mounted should be processed at 45 °. . Specially processed wafers are used for this purpose, and the shape reproducibility is poor. For this process, the photo-and-etch process must be applied to a structure with a vertical step of several tens of micrometers in depth, which is not a typical SOP.

Second, there is a difficulty in developing a new process.

That is, in the case of the optical bench structure according to the prior art, the bottom portion 12a of the groove 12 on which the laser diode 18 is mounted, the side surface 12b inclined at 45 degrees on which the mirror 20 is mounted, and the silicon substrate ( Photographs and etching process technologies are needed to make electrode wirings that pass through three surfaces such as the surface of 10). These photographic and etching process technologies are highly difficult process technologies that have not been successful in the world at present.

Third, the laser bump bonding solder bumps (Au / Sn) 16 are formed by a mold process using a photoresist and an electroplating process, and the solder bumps 16 are formed at the bottom of the groove 12 as shown in FIG. 1. Formed on (12a), the photolithography process in the cavity structure, which has been pointed out as the second problem, also needs to be applied to the solder bump 16 forming process.

As described above, the optical bench structure according to the related art has a low process margin and reproducibility due to the high difficulty of the process technology applied to the manufacturing process as a whole. As a result, the yield is low, and it is difficult to obtain a result having a desired performance. This means that the cost of production must be increased to get the desired result, which is economically inefficient.

SUMMARY OF THE INVENTION The present invention has been made in an effort to improve the above-described problems of the related art, and provides a micro-optical bench structure that is simple in a manufacturing process, does not have a high difficulty in a technology applied to the manufacturing process, and can increase reproducibility. .                         

Another object of the present invention is to provide a method for manufacturing the micro-optic bench structure.

In order to achieve the above technical problem, the present invention provides a semiconductor substrate having a uniform thickness, a light receiving element provided on the semiconductor substrate, a light emitting element provided on the semiconductor substrate at a position spaced apart from the light receiving element, the light receiving element and the It is provided on the semiconductor substrate between the light emitting device to reflect the light emitted from the light emitting device and a micro-optic bench structure characterized in that it comprises an electrode wiring formed to connect the light emitting device and an external power source do.

Here, solder bumps are provided on a portion of the electrode wirings, and the light emitting device may be flip chip bonded onto the solder bumps.

The mirror structure may include a mirror support inclined at a predetermined angle with a surface facing the light emitting element and reflection means provided on an inclined surface of the mirror support.

The mirror support may be a negative photoresist.

In order to achieve the above technical problem, the present invention relates to a first step of forming a first optical device on a semiconductor substrate having a uniform thickness, and related to a second optical device on a region spaced apart from the first optical device on the semiconductor substrate. A second step of sequentially forming members, a third step of forming a mirror structure for vertically reflecting incident light on the semiconductor substrate between the first optical element and the members, and a second optical element on the members It provides a method for manufacturing a micro-optic bench structure, characterized in that it comprises a fourth step of mounting.

The first optical element may be formed in a form embedded in the semiconductor substrate.

The second step may include forming electrode wirings on the semiconductor substrate, forming flip chip bonding means on the electrode wirings, and exposing the first optical element and the first optical element and the flip chip bonding means. Patterning the electrode wirings to expose the semiconductor substrate therebetween. In this case, the forming of the flip chip bonding means may include forming a mold layer on the electrode wiring, forming a hole in which the electrode wiring is exposed in the mold layer, and filling the hole with the flip chip bonding means. And removing the mold layer.

The flip chip bonding means may be formed by an electroplating method.

The third step may include forming a negative photoresist layer covering the first optical element and the members on the semiconductor substrate, forming a light blocking layer on the negative photoresist layer, and the first optical element and the Removing a portion of the light blocking film between the members to expose a portion of the negative photoresist layer, subjecting the exposed area of the negative photoresist layer to vertical exposure and vertical exposure, removing the light blocking film. And developing the negative photoresist layer exposed to the incidence and vertical exposure.

In this case, the incidence of incidence and vertical exposure may be performed such that the surface facing the second optical element of the final result of the negative photoresist layer formed after the development is an inclined surface of 45 °.

On the other hand, the second step is the step of forming an electrode wiring on the semiconductor substrate, patterning the electrode wiring to expose the first optical element and the semiconductor substrate around it and flip chip on the patterning electrode wiring It may comprise the step of forming the bonding means. The forming of the flip chip bonding means may include forming a mold layer covering the patterned electrode wiring on the semiconductor substrate, and forming a hole in the mold layer to expose the patterned electrode wiring. The method may include filling a hole with the flip chip bonding means and removing the mold layer.

In this case, the flip chip bonding means may be solder bumps, may be formed by electroplating, and the mold layer may be formed of a photoresist layer.

The third step may include forming a negative photoresist layer covering the first optical element and the members on the semiconductor substrate, forming a light blocking layer on the negative photoresist layer, and forming the first optical element. And exposing a portion of the negative photoresist layer by removing a portion of the light blocking layer between the members, subjecting the exposed region of the negative photoresist layer to injecting and vertical exposure, the light blocking layer And removing the negative incident photoresist layer and the negative photoresist layer exposed vertically.

In this case, the incidence of incidence and vertical exposure may be performed such that the surface facing the second optical element of the final result of the negative photoresist layer formed after the development becomes an inclined surface of 45 °.

By using this invention, a manufacturing process can be simplified, process margin can fully be secured, and reproducibility can be improved. In addition, according to these results, the performance of the optical bench structure or the apparatus having the structure can be improved, and the yield and productivity can be increased, thereby lowering the production cost.

Hereinafter, a micro optical bench structure and a method of manufacturing the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this process, the thicknesses of layers or regions illustrated in the drawings are exaggerated for clarity.

First, the micro-optic bench structure according to the embodiment of the present invention (hereinafter, the structure of the present invention) will be described.

Referring to FIG. 2, the structure of the present invention includes a light receiving element 42 on a substrate 40. The light receiving element 42 may be a photo diode, for example, and may be provided in a form embedded in the substrate 40. First and second electrode wirings 44a and 44b are formed on the substrate 40 around the light receiving element 42. The first and second electrode wirings 44a and 44b are preferably multilayer wirings in which chromium (Cr) wiring as an attachment layer and gold (Au) wiring as a main wiring are sequentially stacked. In the case of a material layer capable of securing adhesion to the substrate 40, the first and second electrode wirings 44a and 44b may be a single layer. There is a solder bump 46 for flip chip bonding on the first electrode wiring 44a. The solder bump 46 is preferably a double layer in which the gold layer Au and the tin layer Sn are sequentially stacked. However, when the solder bump 46 is a material having excellent adhesion with the light emitting device 48 mounted on the solder bump 46, The solder bumps 46 may be a single layer. A light emitting element 48, for example a laser diode, is mounted on the solder bumps 46. Mirror structures 50a and 52 exist on the substrate 40 between the light emitting element 48 and the light receiving element 42. Mirror supports 50a in mirror structures 50a and 52 are negative photoresisted patterns. The inclined surface M1 facing the light emitting element 48 of the mirror support 50a is inclined at a predetermined angle θ, for example, 45 °. Reflecting means 52, for example a mirror, is attached to the inclined surface M1 of the mirror support 50a. The laser beam emitted from the light emitting element 48 by the reflecting means 52 is immediately reflected upward in the direction perpendicular to the substrate 40.

Next, the manufacturing method of the structure of this invention mentioned above is demonstrated.

First, as shown in FIG. 3, a light receiving element 42 having a form embedded in a predetermined region of the substrate 40 is formed. The substrate 40 may be formed of a silicon substrate. The light receiving element 42 may be a photodiode. An electrode wiring 44 covering the light receiving element 42 is formed on the substrate 40. The electrode wirings 44 may be formed by sequentially stacking an attachment layer and a main wiring. The adhesion layer is to increase the adhesion between the substrate 40 and the main wiring, and may be formed of a chromium layer. The main wiring may be formed of gold wiring. When the main wiring is a material layer having excellent conductivity and excellent adhesion with the substrate 40, the main wiring can be directly formed on the substrate 40 without using a member such as the chromium layer. In other words, when using a material layer having excellent adhesion, the electrode wirings 44 may be formed in a single layer.

4, the mold layer 47 covering the electrode wirings 44 is formed on the substrate 40. The mold layer 47 may be formed of a photoresist layer. After the mold layer 47 is formed, first and second holes h1 and h2 exposing the electrode wiring 44 to the mold layer 47 may be performed by performing a photolithography and an etching process to define a location where solder bumps are to be formed. ). The first and second holes h1 and h2 are formed at positions spaced apart from the light receiving element 42. Thereafter, as illustrated in FIG. 5, the first and second holes h1 and h2 are filled with the solder bumps 46. The solder bumps 46 are used as one of the flip chip bonding means. Accordingly, flip chip bonding means other than the solder bumps 46 may be used. The solder bumps 46 may be formed by sequentially stacking the gold layer and the tin layer. However, the solder bumps 46 may be formed as a single layer when the light emitting device to be formed in a subsequent process and a material layer having excellent adhesion. The solder bumps 46 of the gold layer and the tin layer are preferably formed by an electroplating method, but may be formed by other methods. After the solder bumps 46 are formed, the mold layer 47 is removed using a strip and an ashing process. As a result, as shown in FIG. 6, the solder bump 46 of a complete form is formed on the electrode wiring 44. As shown in FIG.

Next, referring to FIG. 7, the electrode wirings 44 are etched by performing a photographic and etching process defining a region in which the solder bumps 46 are formed and a region in which the second electrode wirings 44b are to be formed. As a result, the first electrode wiring 44a having the solder bumps 46 formed thereon is formed on the substrate 40, and the second electrode wiring 44b is formed in the region close to the light receiving element 42. Although the first and second electrode wirings 44a and 44b appear to be disconnected in the drawing, this is due to the cross-sectional views, and the first and second electrode wirings 44a and 44b are actually connected to each other. The second electrode wiring 44b is connected to an external power source (not shown).

Referring to FIG. 8, a so-called negative photoresist layer 50, known as SU-8, is formed on the substrate 40 and covers the solder bumps 46 and the first and second electrode wirings 44a and 44b. Bake is performed for a predetermined time. The light blocking layer 60 is formed on the negative photoresist layer 50. The light blocking film 60 is for blocking ultraviolet rays used for exposing the negative photoresist layer 50. After the light blocking film 60 is formed, the light blocking film 60 is patterned to expose a predetermined area A1 of the negative photoresist layer 50 between the first electrode wiring 44a and the light receiving element 42. Incidental exposure UV1 and vertical exposure UV2 are performed on the exposed area A1 of the negative photoresist layer 50. Incident light exposure UV1 and vertical exposure UV2 are both performed using ultraviolet rays. The exposure order may be performed first by an incidence exposure UV1 or may be performed by vertical exposure UV2 first. By this exposure, a mirror support (see 50a in FIG. 9) having an inclined surface is formed in the exposed area A1 of the negative photoresist layer 50.

As described above, the light blocking film 60 is removed after injecting and vertical exposure (UV1, UV2). Next, the developing process is performed. In the developing step, the portion that is not exposed in the exposure process, that is, the part covered with the light blocking film 60 is removed from the negative photoresist layer 50. In the developing step, a part of the exposed area A1 is also removed, but the width to be removed narrows downward. After the development process, the negative photoresist layer 50 is hard baked for a predetermined time.

9 shows the result of the development process and the hard bake process.

Referring to FIG. 9, it can be seen that the mirror support 50a is formed on a predetermined region of the substrate 40 between the first electrode wiring 44a and the light receiving element 42. The mirror support 50a is a development result of the negative photoresist layer 50 (FIG. 8). The surface M1 facing the first electrode wiring 44a of the mirror support 50a is inclined at a predetermined angle θ due to the exposure process. It is preferable that the inclination angle (theta) of the inclined surface M1 is about 45 degrees.

Next, as shown in FIG. 10, a shadow mask 64 designed to expose the inclined surface M1 of the mirror support 50a is disposed on the substrate 40 on which the mirror support 50a is formed. In this state, an aluminum (Al) deposition process is performed. At this time, since the remaining portion other than the inclined surface M1 of the mirror support 50a is masked by the shadow mask 64, the aluminum 66 is deposited only on the inclined surface M1 of the mirror support 50a. As a result, the laser beam reflecting means 52 of uniform thickness is formed in the inclined surface M1 of the mirror support 50a. In this way, a mirror structure composed of the mirror support 50a and the reflecting means 52 is formed on the substrate 40. The reflecting means 52 is a mirror made of aluminum (Al). Since the reflecting means 52 is for the reflection of the laser beam emitted from the light emitting element to be mounted in a subsequent process, it is preferable to form at the proper position of the inclined surface M1 in consideration of the height at which the light emitting element is mounted. After forming the reflecting means 52, the shadow mask 64 is removed.

Next, as shown in FIG. 11, the light emitting device 48 is mounted on the solder bumps 46 using flip chip bonding. The light emitting element 48 may be, for example, a laser diode.

In this way, the micro-optic bench structure provided with the light emitting element and the light receiving element is completed.

While many details are set forth in the foregoing description, they should be construed as illustrative of preferred embodiments, rather than to limit the scope of the invention. For example, those skilled in the art may form the light receiving element 42 on the substrate 40. In addition, the reflecting means 52 may be formed of another material having a high reflectance of the laser beam instead of aluminum. Further, the light emitting element may be formed later than the light receiving element. In addition, the electrode wiring patterning process may be performed first, and then a photolithography process and an electroplating process may be performed to form solder bumps on the patterned electrode wiring. In addition, after the light emitting device is mounted on the solder bumps, reflecting means may be formed on the inclined surface of the mirror support. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be determined by the technical spirit described in the claims.

As described above, the micro-optic bench structure according to the present invention does not form a groove in a silicon substrate having a predetermined inclination angle, but rather forms a light emitting device, an electrode wiring, a mirror structure, and the like on a general semiconductor substrate having a uniform thickness. do. The process of forming such members on a general semiconductor substrate is not only a simple process, but also has a high level of difficulty of technology, and since it is clearly established and proven to be reliable, it is possible to increase reproducibility and reliability. Therefore, by using the optical bench structure and the manufacturing method of the present invention, the production cost can be reduced, yield and fish properties can be increased. And process sequences can be reduced to less than 50% of the current.

Claims (26)

A semiconductor substrate of uniform thickness; A light receiving element provided in the semiconductor substrate; A light emitting device provided on the semiconductor substrate at a position spaced apart from the light receiving device; A mirror structure provided on the semiconductor substrate between the light receiving element and the light emitting element to reflect light emitted from the light emitting element; And An electrode wiring formed to connect the light emitting element to an external power source; The mirror structure, A mirror support inclined at a predetermined angle with a surface facing the light emitting element; Micro-optic bench structure, characterized in that consisting of reflecting means provided on the inclined surface of the mirror support. The micro-optic bench structure as claimed in claim 1, wherein solder bumps are provided on a portion of the electrode wirings, and the light emitting device is flip-chip bonded to the solder bumps. 2. The micro-optic bench structure as claimed in claim 1, wherein the electrode wiring is composed of an adhesion layer and a main wiring stacked sequentially. 4. The micro-optic bench structure as claimed in claim 3, wherein the adhesion layer is a chromium (Cr) layer and the main wiring is a gold (Au) wiring. delete 2. The micro-optic bench structure as claimed in claim 1, wherein the mirror support is made of negative photoresist. 2. The micro-optic bench structure as claimed in claim 1, wherein the reflecting means is a mirror. The micro-optic bench structure as claimed in claim 1, wherein the light receiving element is embedded in the semiconductor substrate. Forming a first optical element on a semiconductor substrate having a uniform thickness; A second step of sequentially forming members associated with a second optical element on a region spaced apart from the first optical element of the semiconductor substrate; A third step of forming a mirror structure on the semiconductor substrate between the first optical element and the members to vertically reflect incident light; And And a fourth step of mounting a second optical element on said members. 10. The method of claim 9, wherein the first optical element is formed in a form embedded in the semiconductor substrate. The method of claim 9, wherein the second step, Forming electrode wiring on the semiconductor substrate; Forming flip chip bonding means on the electrode wiring; And Patterning the electrode wiring such that the first optical element is exposed and the semiconductor substrate between the first optical element and the flip chip bonding means is exposed. The method of claim 11, wherein the forming of the flip chip bonding means comprises: Forming a mold layer on the electrode wiring; Forming a hole in the mold layer to expose the electrode wiring; Filling the hole with the flip chip bonding means; And Removing the mold layer. 13. The method of claim 11 or 12, wherein the flip chip bonding means is solder bumps. The method of claim 12, wherein the mold layer is formed of a photoresist layer. The method of claim 12, wherein the flip chip bonding means is formed by an electroplating method. 12. The method of claim 11, wherein the electrode wiring is formed by sequentially stacking an attachment layer and a main wiring. The method of claim 16, wherein the adhesion layer is formed of a chromium layer, and the main wiring is formed of a gold wire. The method of claim 9, wherein the third step, Forming a negative photoresist layer covering the first optical element and the members on the semiconductor substrate; Forming a light blocking film on the negative photoresist layer; Removing a portion of the light blocking film between the first optical element and the members to expose a portion of the negative photoresist layer; Subjecting the exposed area of the negative photoresist layer to incidence and vertical exposure; Removing the light blocking film; And Developing the incidence and vertically exposed negative photoresist layer. 19. The micro-optic bench according to claim 18, wherein the incidence of incidence and vertical exposure are performed such that the surface facing the second optical element of the final result of the negative photoresist layer formed after the development is an inclined plane of 45 degrees. Method of making the structure. The method of claim 9, wherein the second step, Forming electrode wiring on the semiconductor substrate; Patterning the electrode wirings to expose the first optical element and the semiconductor substrate around the first optical element; And And forming flip chip bonding means on the patterned electrode wirings. The method of claim 20, wherein forming the flip chip bonding means comprises: Forming a mold layer on the semiconductor substrate to cover the patterned electrode wiring; Forming a hole in the mold layer to expose the patterned electrode wiring; Filling the hole with the flip chip bonding means; And Removing the mold layer. 21. The method of claim 20, wherein the flip chip bonding means is solder bumps. 22. The method of claim 21, wherein the flip chip bonding means is formed by electroplating. 22. The method of claim 21, wherein the mold layer is formed of a photoresist layer. The method of claim 20, wherein the third step, Forming a negative photoresist layer covering the first optical element and the members on the semiconductor substrate; Forming a light blocking film on the negative photoresist layer; Removing a portion of the light blocking film between the first optical element and the members to expose a portion of the negative photoresist layer; Subjecting the exposed area of the negative photoresist layer to incidence and vertical exposure; Removing the light blocking film; And Developing the incidence and vertically exposed negative photoresist layer. 27. The micro-optic bench according to claim 25, wherein the incidence of incidence and vertical exposure are performed such that the surface facing the second optical element of the final result of the negative photoresist layer formed after the development is an inclined plane of 45 degrees. Method of making the structure.

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