Optical module and method of manufacture thereof, semiconductor device, and optical transmission device

An optical module comprising: an optical fiber; an optical element having an optical section and with a fixed position relative to the optical fiber; and a semiconductor chip electrically connected to the optical element, and the optical element and semiconductor chip being packaged. A hole is formed in the semiconductor chip, and the optical element is mounted on the semiconductor chip with the optical section facing the hole, and the optical fiber is inserted in the hole and fitted to the semiconductor chip.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical module and method of manufacture thereof, to a semiconductor device, and to an optical transmission device.

2. Description of Related Art

In recent years, there has been a trend toward increased speeds and volumes in data communications, and developments in optical communications continue. Generally, in optical communications, an electrical signal is converted to an optical signal, the optical signal is transmitted through an optical fiber, and then the received optical signal is converted to an electrical signal. The conversion between electrical signals and optical signals is done by optical elements.

For example, Japanese Patent Application Laid-Open No. 10-339824 discloses an optical fiber positioned and fixed on a platform in which a V-groove is formed, to constitute an optical module.

However, a conventional optical module has an optical fiber and optical element formed integrally, and it is further necessary to electrically connect this optical module to a semiconductor chip.

SUMMARY OF THE INVENTION

The present invention solves this problem, and has as its objective the provision of an optical module not requiring connection to a semiconductor chip and method of manufacture thereof, of a semiconductor device and of an optical transmission device.

(1) According to a first aspect of the present invention, there is provided an optical module of the present invention comprising:

an optical waveguide;

an optical element having an optical section; and

a semiconductor chip electrically connected to the optical element,

wherein the optical element and the semiconductor chip are packaged.

According to this aspect of the present invention, the optical element and semiconductor chip are packaged, and the semiconductor chip is incorporated into the optical module. Therefore, further connection of the optical module to a semiconductor chip is not required, and handling is made easier.

(2) In this optical module, a hole may be formed in the semiconductor chip; the optical waveguide may be inserted into the hole; and the optical element may be disposed so that the optical section and one end surface of the inserted optical waveguide are opposed.

By means of this, the optical waveguide is positioned by the hole formed in the semiconductor chip, and therefore the positioning accuracy of the optical section of the optical element and the end surface of the optical waveguide is increased.

(3) In this optical module, the hole may be a through hole.

(4) In this optical module, a light-transmitting sealant may be provided at the through hole.

By means of this, the optical waveguide is contacted with the sealant, and the positioning achieved.

(5) In this optical module, an underfill material may be provided between the optical element and the semiconductor chip.

By means of this, the optical element and semiconductor chip are protected, and also the connection therebetween can be made stable.

(6) In this optical module, an interconnect pattern may be formed on the semiconductor chip; a plurality of electrodes may be formed on the optical element; and at least one of the plurality of electrodes may be electrically connected to the interconnect pattern.

By means of this, since the optical element is mounted on the semiconductor chip, the optical module can be made more compact. To the semiconductor material constituting the semiconductor chip, the method of manufacture of the semiconductor device can be applied, and an interconnect pattern of high accuracy can be formed.

(7) This optical module may further comprise a substrate for supporting at least either of the semiconductor chip and the optical element.

(8) In this optical module, the substrate may assist the dispersion of heat from at least either of the semiconductor chip and the optical element.

(9) This optical module may further comprise external terminals provided on the substrate, and electrically connected to at least either of the optical element and the semiconductor chip.

(10) In this optical module, the semiconductor chip and the optical element may be sealed with resin.

By means of this, the semiconductor chip and optical element are protected by the resin.

(11) According to a second aspect of the present invention, there is provided a semiconductor device comprising: an optical element having an optical section; and a semiconductor chip electrically connected to the optical element, wherein the optical element and the semiconductor chip are packaged.

According to this aspect of the present invention, since the optical element and semiconductor chip are packaged, further connection of the optical module and semiconductor chip is not required, and handling is made easier.

(12) In this semiconductor device, the optical element and the semiconductor chip may be stacked.

(13) In this semiconductor device, a hole may be formed in the semiconductor chip; the optical element may be disposed so that one end surface of the semiconductor chip and the optical section are opposed; and the optical element and the semiconductor chip may be stacked.

(14) In this semiconductor device, the optical element and the semiconductor chip may be disposed on a substrate.

(15) In this semiconductor device, a hole may be formed in the substrate; the optical element may be disposed so that one end surface of the semiconductor chip and the optical section are opposed; and the optical element may be disposed on the substrate.

(16) According to a third aspect of the present invention, there is provided an optical transmission device comprising:

an optical waveguide;

a light-emitting element mounted with a light-emitting section facing one end surface of the optical waveguide;

a semiconductor chip electrically connected to the light-emitting element and packaged with the light-emitting element;

a light-receiving element mounted with a light-receiving section facing the other end surface of the optical waveguide; and

a semiconductor chip electrically connected to the light-receiving element and packaged with the light-receiving element.

According to this aspect of the present invention, the light-emitting element or light-receiving element and the semiconductor chip are packaged, and incorporate a semiconductor chip. Therefore, further connection between the light-emitting element or light-receiving element and the semiconductor chip is not required, and handling is made easier.

(17) This optical transmission device may further comprise: a plug connected to the light-emitting element; and a plug connected to the light-receiving element.

(18) According to a fourth aspect of the present invention, there is provided a method of manufacture of an optical module having at least an optical waveguide, an optical element having an optical section, and a semiconductor chip. This method comprises the steps of:

electrically connecting the optical element and the semiconductor chip;

relatively positioning the optical waveguide and the optical element; and

packaging the optical element and the semiconductor chip.

According to this aspect of the present invention, the optical element and semiconductor chip are packaged, and further connection of the optical module obtained to a semiconductor chip is not required, and handling is made easier.

(19) In this method of manufacture of an optical module, an interconnect pattern may be formed on the semiconductor chip; the optical element may have a plurality of electrodes; and the step of electrically connecting the optical element and the semiconductor chip may bond at least one of the plurality of electrodes to the interconnect pattern.

By means of this, merely by bonding the electrodes to the interconnect pattern, the electrical connection between the optical element and semiconductor chip can be achieved simply. Since the optical element is mounted on the semiconductor chip, the optical module can be made more compact. To the semiconductor material constituting the semiconductor chip, the method of manufacture of the semiconductor device can be applied, and an interconnect pattern of high accuracy can be formed.

(20) In this method of manufacture of an optical module, the electrode and the interconnect pattern may be bonded with a soldering material; and the positions of the optical element and semiconductor chip may be determined by the surface tension of the fused soldering material.

By means of this, by the surface tension of the soldering material the positioning of the optical element and semiconductor chip is carried out, and therefore a positioning step is not required.

(21) In this method of manufacture of an optical module, a hole may be formed in the semiconductor chip; and the step of relatively positioning the optical waveguide and the optical element may include a step of inserting the optical waveguide into the hole.

By means of this, by inserting the optical waveguide into the hole, the positioning of the optical waveguide and semiconductor chip is determined. Therefore, if the positioning of the optical element and semiconductor chip is carried out, the positioning of the optical element and optical waveguide can be carried out simply.

(22) In this method of manufacture of an optical module, the hole may be formed by a laser.

(23) In this method of manufacture of an optical module, the hole may be formed by etching.

(24) This method of manufacture of an optical module may further comprise a step of forming a depression in the region in which the hole is to be formed in the semiconductor chip by anisotropic etching, and then penetrating the depression by a laser, to form the hole in the semiconductor chip.

Anisotropic etching is widely carried out by the process of manufacture of a semiconductor device, and allows a depression of high accuracy to be formed. By means of anisotropic etching, the cross-section of the depression forms a V-shape, and therefore a hole formed by penetrating the depression with a laser has opening extremities which are tapered. Therefore, a hole with tapered opening extremities can be formed simply. The hole taper acts as a guide when the optical waveguide is inserted.

(25) This method of manufacture of an optical module may further comprise a step of providing an underfill material between the semiconductor chip and the optical element.

By means of this, by means of the underfill material, the optical element and semiconductor chip can be protected, and also the connection therebetween can be made stable.

(26) In this method of manufacture of an optical module, the step of packaging the optical element and the semiconductor chip may comprise sealing the optical element and the semiconductor chip with a resin.

By means of this, the semiconductor chip and optical element can be protected by the resin.

(27) This method of manufacture of an optical module may further comprise a step of providing a substrate to at least either of the semiconductor chip and the optical element.

(28) This method of manufacture of an optical module may further comprise a step in which external terminals electrically connected to at least either of the optical element and the semiconductor chip are provided on the substrate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is now described in terms of a number of preferred embodiments, with reference to the drawings.

First Embodiment

FIG. 1shows a first embodiment of an optical module to which the present invention is applied. The optical module comprises an optical element10, a semiconductor chip20, and an optical fiber30. The optical fiber30is an example of an optical waveguide. Since this optical module includes the semiconductor chip20, it may also be defined as a semiconductor device. This applies similarly to all of the below embodiments.

The optical element10may be a light-emitting element or a light-receiving element. As an example of a light-emitting element may be used a surface emitting element, and particularly a surface emitting laser. A surface emitting element such as a surface emitting laser emits light in a direction perpendicular to the substrate. The optical element10includes an optical section12. When the optical element10is a light-emitting element, the optical section12is a light-emitting section, and when the optical element10is a light-receiving element, the optical section12is a light-receiving section.

The optical element10is fixed in relative position with respect to the optical fiber30. More specifically, the optical section12of the optical element10and the end surface of the optical fiber30are preferably fixed in relative position. In more concrete terms, the optical section12is commonly disposed to oppose the end surface of the optical fiber30. In this embodiment, the optical section12faces a hole28in the semiconductor chip20.

The optical element10has at least one (generally two or more) electrodes. For example, on the surface on which the optical section12is formed, first electrodes14may be provided. It should be noted that of the plurality of first electrodes14, at least one may be a dummy electrode. A dummy electrode may be formed of the same material as the first electrodes14, but has no electrical connection within the optical element10. For example, when the first electrodes14are formed such that if joined by straight lines they form a polygon of at least three sides, one or more thereof may be dummy electrodes. By this means, the optical element10can be stably supported with at least three points of fixture.

On a surface different from the surface on which the first electrodes14are provided, second electrodes16may be provided. When the optical element10is a surface light-emitting laser or other semiconductor laser, the second electrodes16may be provided on the opposite surface to the surface on which the first electrodes14are provided.

The semiconductor chip20is for driving the optical element10. The semiconductor chip20has an internal circuit for driving the optical element10. On the semiconductor chip20are formed a plurality of electrodes (or pads)22which are electrically connected to the internal circuit. On the surface on which the electrodes22are formed, an interconnect pattern24electrically connected to at least one electrode22is preferably formed.

The semiconductor chip20and optical element10are electrically connected. For example, the first electrodes14of the optical element10and the interconnect pattern24formed on the semiconductor chip20are electrically connected. For the connection, wires or the like may be used, or a metal bond of solder26or the like as a soldering material, or the first electrodes14and the interconnect pattern24may be bonded with an anisotropic conductive material (film) interposed. In this case, the optical element10is mounted face-down on the semiconductor chip20. By means of this, not only can the electrical connection be made by the solder26, but also the optical element10and semiconductor chip20can be fixed by the solder26. It should be noted that of the first electrodes14, those which are dummy electrodes are also preferably connected to the interconnect pattern24. By means of this, the optical element10can be fixed to the semiconductor chip20in a stable state.

The second electrodes16of the optical element10and the interconnect pattern24are electrically connected. For the connection, wires27or the like may be used, or a conductive paste may be provided from the second electrodes16to the interconnect pattern24.

Between the optical element10and semiconductor chip20, an underfill material40may be provided. When the underfill material40covers the optical section12of the optical element10, it is preferable for the underfill material40to be transparent. The underfill material40covers and protects the electrical connection between the optical element10and the semiconductor chip20, and also protects the surface of the optical element10and semiconductor chip20. Furthermore, the underfill material40maintains the bonding between the optical element10and semiconductor chip20.

In the semiconductor chip20, a hole (such as a through hole)28may be formed. The optical fiber30passes through the hole28. The hole28is formed to avoid the internal circuit, and to extend from the surface where the electrodes22are formed to the opposite surface. In the hole28may be provided a light-transmitting sealant25in the opening of the surface in which the electrodes22are formed. By providing the sealant25one end of the hole28is sealed, and positioning of the end of the optical fiber30can be achieved. The sealant25can be provided by forming the hole28from the surface (the rear surface) opposite to the surface on which the sealant25is provided, and leaving a passivation film of SiO2, or SiNx, or the like formed on the surface (the front surface) on which the sealant25is provided. At at least one opening extremity of the hole28, a taper29is preferably formed. By forming the taper29, it is made easier to insert the optical fiber30into the hole28.

The semiconductor chip20may be mounted on a substrate42. More specifically, the semiconductor chip20may be adhered to the substrate42by an adhesive44. In the substrate42a hole46is formed. The hole46is formed in a position to communicate with the hole28in the semiconductor chip20. The adhesive44adhering the semiconductor chip20and the substrate42is provided so as not to block the two holes28and46, in order not to impede communication therebetween. The hole46in the substrate42is formed with a taper so as to have an internal diameter which is larger on the side opposite to the semiconductor chip20. By means of this, it is made easier to insert the optical fiber30.

The substrate42may be formed of an insulating material such as resin, glass, or ceramic, but may also be formed of a conductive material such as metal. When the substrate42is of a conductive material, at least on the surface on which the semiconductor chip20is attached, an insulating film43is preferably formed. It should be noted that in the below embodiments also, similar materials can be used for the substrate42.

The substrate42preferably has high thermal conductivity. According to this, the substrate42assists the dispersion of heat from at least one of the optical element10and semiconductor chip20. In this case, the substrate42is a heat sink or heat spreader. In this embodiment, since the semiconductor chip20is adhered to the substrate42, the semiconductor chip20can be cooled directly. It should be noted that the adhesive44adhering the semiconductor chip20and substrate42is preferably thermally conductive. Furthermore, since the semiconductor chip20is cooled, the optical element10bonded to the semiconductor chip20is also cooled.

On the substrate42is provided an interconnect pattern48. On the substrate42are provided external terminals50. In this embodiment, the external terminals50are leads. The interconnect pattern48formed on the substrate42is connected, for example by wires52, to at least one of the electrodes22of the semiconductor chip20, the interconnect pattern24formed on the semiconductor chip20, and the first and second electrodes14and16of the optical element10. The interconnect pattern48may be electrically connected to the external terminals50.

The optical fiber30includes a core and a cladding which concentric-circularly surrounds the core, so that light is reflected by the boundary between the core and the cladding, trapped within the core, and thus transmitted. The periphery of the cladding is commonly protected by a jacket.

The optical fiber30is inserted into the hole28in the semiconductor chip20. The optical section12of the optical element10faces into the hole28in the semiconductor chip20. Therefore, the optical fiber30inserted into the hole28is positioned with respect to the optical section12.

The optical fiber30is also passed through the hole46in the substrate42. The hole46has an internal diameter that gradually decreases toward the hole28in the semiconductor chip20, and on the surface opposite to that of the semiconductor chip20, the internal diameter of the opening of the hole46is larger than the optical fiber30. The gap between the optical fiber30and the internal surface of the hole46is preferably filled with a filling material54such as resin. The filling material54fixes the optical fiber30and also functions to prevent its removal.

In this embodiment, the optical element10and semiconductor chip20are sealed with a resin56. The resin56also seals the electrical connection between the optical element10and the semiconductor chip20and the electrical connection between the semiconductor chip20and the interconnect pattern48formed on the substrate42.

With this embodiment of the optical module, the optical element10and semiconductor chip20are packaged. Therefore, since it is not always necessary to make a connection of the driver circuit to the optical module, handling is made easier.

This embodiment has the above described construction, and the method of manufacture thereof is now described.

First, an optical element10, semiconductor chip20, and optical fiber30are prepared. The optical element10comprises an optical section12, and first and second electrodes14and16. On the semiconductor chip20, preferably on the surface on which the electrodes22are formed, the interconnect pattern24may also be formed. The hole28may be formed in the semiconductor chip20. Preferably the interconnect pattern24and hole28of the semiconductor chip20are formed with accurate relative positioning.

The method of forming the hole28is now described with reference toFIGS. 2Ato2C. These figures show a vertical sectional view passing through the location of formation of the hole28in the semiconductor chip20. As shown inFIG. 2A, a depression21is formed in the semiconductor chip20. The depression21is formed in the location of the opening of the hole28. Preferably, the depression21is formed in both surfaces in which the hole28opens. The semiconductor chip20is commonly constructed of silicon, and therefore anisotropic etching can be applied to form the depression21with a triangular vertical-section accurately along the crystal planes. Alternatively, the depression21may be formed with a rectangular vertical-section. The form of the opening of the depression21is not particularly restricted, but it may be rectangular. When the opening of the depression21is rectangular, the length of one side is preferably more than the diameter of the optical fiber30. By means of this, at least a part of the depression21can form the taper29.

Next, as shown inFIG. 2B, the semiconductor chip20is bored between the pair of depressions21on mutually opposite sides. For example, a laser can be used. That is to say, laser light can be beamed into one depression21, and the semiconductor chip20bored. Further, to the hole bored between the pair of depressions21, etching is applied, to increase the diameter of the hole, and form the hole28as shown in FIG.2C. It should be noted that at least a part of the depression21is preferably left remaining at the opening of the hole28. By means of this, at least a part of the depression21can form the taper29.

Alternatively, the optical excitation electropolishing method can be applied to the formation of the hole28.

This embodiment includes a step of electrically connecting the optical element10and semiconductor chip20. For example, the first electrodes14of the optical element10and the interconnect pattern24formed on the semiconductor chip20are bonded. Alternatively, the first electrodes14and the electrodes22formed on the semiconductor chip20are bonded.

As a means of bonding, if solder26is used, a self-alignment effect is obtained. That is to say, when molten solder26is interposed between the first electrodes14and the interconnect pattern24or the electrodes22, the surface tension of the molten solder26automatically positions the optical element10. On the interconnect pattern24it is preferable for lands to be formed on which the solder26is provided. The positioning of the optical element10is carried out by the self-alignment effect, and therefore the optical section12of the optical element10can be automatically faced to the hole28in the semiconductor chip20.

The second electrodes16of the optical element10and the interconnect pattern24formed on the semiconductor chip20are electrically connected. For the connection, wires27can be used.

This embodiment includes a step of attaching at least either of the optical element10and semiconductor chip20to the substrate42. For example, using the adhesive44, the semiconductor chip20is adhered to the substrate42. When the hole28is formed in the semiconductor chip20, the hole46in the substrate42communicates with the hole28in the semiconductor chip20.

This embodiment includes a step of providing external terminals50on the substrate42. In this embodiment, leads being the external terminals50are provided on the substrate42, and are electrically connected to the interconnect pattern48. The external terminals50are electrically connected to at least either of the optical element10and semiconductor chip20through the interconnect pattern48.

This embodiment includes a step of relatively positioning and disposing the optical element10and optical fiber30. For example, the optical fiber30is inserted in the hole28formed in the semiconductor chip20. It should be noted that if the taper29is formed at the opening of the hole28, the optical fiber30can be inserted more easily. If the hole46in the substrate42is formed so as to enlarge toward the surface from which the optical fiber30is inserted, the optical fiber30can be inserted more easily.

Simply by inserting the optical fiber30in the hole28, the positioning of the optical fiber30and semiconductor chip20can be carried out. If the semiconductor chip20and optical element10are accurately positioned, then the relative positioning of the optical fiber30and optical element10can be carried out. That is to say, simply by inserting the optical fiber30in the hole28, the relative positioning of the optical fiber30and optical element10can be carried out.

This embodiment may include a step for preventing the optical fiber30from being pulled out. For example, the optical fiber30may be passed through the hole46in the substrate42and inserted in the hole28in the semiconductor chip20, then the hole46in the substrate42filled with the filling material54. If the filling material54is cured, the optical fiber30is fixed to the substrate42, and therefore the optical fiber30can be prevented from being pulled out of the hole28in the semiconductor chip20.

This embodiment may include a step of packaging the optical element10and semiconductor chip20. For example, between the optical element10and semiconductor chip20is filled with the underfill material40. By means of this, the surfaces of the optical element10and semiconductor chip20are protected, the electrical connection between the two is protected, and the connection state of the two is maintained.

Furthermore, at least the exposed surface of the optical element10and semiconductor chip20, the electrical connection between the two, and the electrical connection between at least either of the optical element10and semiconductor chip20and the interconnect pattern48formed on the substrate42, are preferably sealed with the resin56or the like. By means of the above process, an optical module with the optical element10and semiconductor chip20packaged can be obtained.

The present invention is not limited to the above-described embodiment, and various modifications described below are possible.

Second Embodiment

FIG. 3shows a second embodiment of an optical module to which the present invention is applied. This optical module differs from the first embodiment in the construction of external terminals60. That is to say, the external terminals60are provided on the surface of a substrate62. For example, on one surface of the substrate62an interconnect pattern64is formed, and the external terminals60, electrically connected to the interconnect pattern64through through holes66, are formed on the other surface of the substrate62. The external terminals60may be for example solder balls. By means of this, the optical module can be surface mounted. The optical module of this embodiment can also be packaged by a resin68or the like.

In this embodiment, apart from the above-described points, the description of the first embodiment applies, and more detailed explanation is omitted here.

Third Embodiment

FIG. 4shows a third embodiment of an optical module to which the present invention is applied. This optical module has a lead frame70, and the extremities of the lead frame70(outer leads) are external terminals72.

The lead frame70is adhered to a substrate74. When a semiconductor device lead frame70is used, the substrate74is adhered to die pads71of the lead frame70. For the adhesion, an adhesive not shown in the drawings can be used. The substrate74may be formed of a resin or the like, or may be formed of silicon or glass. On the substrate74an interconnect pattern76is formed. In particular, when the substrate74is formed of silicon, the manufacturing process of the semiconductor device can be applied, and a precision interconnect pattern76can be formed.

In this embodiment, an optical element78and a semiconductor chip80are mounted on the substrate74. The optical element78and semiconductor chip80are bonded by face-down bonding to the interconnect pattern76on the substrate74. The interconnect pattern76is electrically connected to the lead frame70by wires75or the like. By means of wires77, the interconnect pattern76and at least either of the optical element78and semiconductor chip80may be electrically connected.

An optical fiber82is positioned by means of a hole84formed in the substrate74. The portion of the lead frame70which is adhered to the substrate74preferably has formed a hole avoiding the optical fiber82.

For other aspects of the construction, the description of the first embodiment applies. The optical module of this embodiment is also packaged by a resin86or the like.

It should be noted that in place of the “semiconductor chip” of the present invention, a chip including an internal circuit not using a semiconductor may also be applied, and in this case the same benefit as the present invention can be obtained.

Fourth Embodiment

FIG. 5shows an embodiment of an optical transmission device to which the present invention is applied. An optical transmission device90is used to mutually connect electronic instruments92such as a computer, a display, a memory device, and a printer. The electronic instruments92may equally be data communications devices. The optical transmission device90may have plugs96provided at both ends of a cable94. The cable94includes one or a plurality of (at least one) optical fiber(s)30(see FIG.1). The plugs96incorporate-semiconductor chip20. The fixing of the optical fiber30to the optical element10or the semiconductor chip20is as described above.

The optical element20connected to one end of the optical fiber30is a light-emitting element. An electrical signal output from one electronic instrument92is converted to an optical signal by the optical element20being a light-emitting element. The optical signal passes through the optical fiber30, and is input to the optical element20at the other end. This optical element20is an light-receiving element, and converts the input optical signal to an electrical signal. The electrical signal is input to the other electronic instrument92. In this way, this embodiment of the optical transmission device90enables information to be transferred between the electronic instruments92by means of an optical signal.

Fifth Embodiment

FIG. 6shows the use of an embodiment of an optical transmission device to which the present invention is applied. The optical transmission device90connects electronic instruments100. As the electronic instruments100may be cited liquid crystal display monitors or digital support CRTs (These may be used in the financial, communications marketing, medical, and educational fields.), liquid crystal projectors, plasma display panels (PDP), digital TV, retail cash registers (for Point of Sale Scanning (POS)), video, tuners, games machines, printers, and so on.

Sixth Embodiment

FIG. 7shows an embodiment of an optical module to which the present invention is applied. This optical module comprises a semiconductor chip110, a plurality of optical elements10, and a plurality of optical fibers30. In the semiconductor chip110are formed a plurality of holes112, and an optical fiber30is inserted into each of the holes112. Corresponding to each optical fiber30, an optical element10is provided. In the example shown inFIG. 7, the optical module has four optical elements10, and when these are used to transmit a color image signal, the optical elements10and optical fibers30are used to transmit red, green, and blue signals and a clock signal.

For other aspects of the construction, the description of the first embodiment applies. The optical module of this embodiment can also be packaged by a resin or the like.

Seventh Embodiment

FIG. 8shows an embodiment of an optical module to which the present invention is applied. This optical module has an optical element210, a semiconductor chip220, and an optical fiber30. The optical element210is provided with a stopper214so that the end of the optical fiber30does not contact an optical section212. The stopper214is provided in a position being the surface of the optical element210on which the optical section212is provided, corresponding to within the area of the end surface of the optical fiber30. By forming the stopper214to be higher than the optical section212, the end surface of the optical fiber30is prevented from contacting the optical section212.

In the semiconductor chip220, a hole222is formed for the optical fiber30to be passed through. The hole222is formed with opening extremities and a central part of larger diameter than the opening extremities. The opening extremities and central part are connected by tapers.

The hole222of this shape can be formed as follows. First, a layer patterned to form an opening in the region in which the hole222is to be formed is formed on the semiconductor chip220. This layer may be of resist, or may be an oxide film, or may be a film formed by applying chemical vapor deposition (CVD). Then the opening in the layer of resist or the like (the surface of the semiconductor chip220) is etched. For the etching it is preferable that dry etching be applied. The dry etching may be reactive ion etching (RIE). As the etching may be applied wet etching. In this way, on the surface of the semiconductor chip220, a depression (not a through hole) is formed.

Then in the portion of the semiconductor chip220where the depression is formed, using a laser (for example a YAG laser or CO2laser) or the like, a small hole is formed. The laser beam can be directed to recognize the position of the depression. The laser beam may be directed from one side of the semiconductor chip220, or the laser beam may be directed from both sides of the semiconductor chip220(either sequentially or simultaneously). If the laser beam is directed from both sides, the effect on the semiconductor chip220is reduced. It should be noted that when directing the laser beam from both sides, it is preferable for depressions to be formed in both surfaces of the semiconductor chip220.

Next the small hole is enlarged to form the hole222. For example, applying wet etching, the internal wall of the small hole may be etched. As etchant may be used, for example, a mixture of hydrofluoric acid and ammonium fluoride in aqueous solution (buffered hydrofluoric acid). Then the layer of resist or the like is removed as required.

It should be noted that elements may be formed on the semiconductor chip220after forming the hole222, but if the presence of the hole222makes the formation of elements difficult, elements may be formed first.

For other aspects of the construction, the description of the first embodiment applies. The optical module of this embodiment can also be packaged by a resin or the like. It should be noted that the interior of the hole222is preferably filled with the filling material54fixing the optical fiber30.

In the above embodiments, an optical fiber was used as an optical waveguide, but a sheet form or strip form optical waveguide may equally be used. The optical waveguide may be formed of polyimide resin.