JPH05335251A - Semiconductor manufacturing equipment - Google Patents

Abstract

PURPOSE:To simplify a manufacturing process and to acquire a laser element with improved characteristic by providing a laser interference exposure device to an MOCVD device and by introducing laser light of specified wavelength to a substrate surface at a specified angle. CONSTITUTION:Laser light output from a single laser light source 2 is divided into two beam of two directions by a beam splitter 4. One beam is adjusted at a specified incident angle by mirrors 12a, 12a2 and directed to an InP substrate 5. The other beam is adjusted to a specified incident angle by a mirror 12b and directed to the InP substrate 5. The beams are based through optical windows 3b, 3a and generate interference fringe. Meanwhile, laser incident angle and wavelength are set in advance to make interference fringe coincide with a lattice interval of required diffraction grating. Thereby, formation of a diffraction pattern of interference fringe and formation of a formation film thereafter can be performed successively inside a formation chamber 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing apparatus. More specifically, it relates to a manufacturing apparatus for manufacturing a distributed feedback (DFB) laser that operates in a longitudinal single mode.

[0002]

2. Description of the Related Art Conventionally, an optical feedback obtained by forming a diffraction grating along an optical waveguide in order to obtain a longitudinal single mode and coupling a forward wave and a backward wave in the waveguide is near a Bragg frequency. A distributed feedback laser, for example, as shown in FIG. 2 is manufactured by using the principle that the intensity becomes the strongest and the wavelength selectivity occurs in the optical feedback.

Such a distributed feedback laser is manufactured using an apparatus having a combination of a laser interference exposure apparatus for forming a diffraction grating, an etching apparatus and a MOCVD apparatus.

FIG. 3 is a diagram for explaining with time the method for manufacturing a diffraction grating of a distributed feedback laser using this conventional apparatus. The manufacturing method will be described below. InP substrate 3
1 Apply photoresist material 32a on the surface,
Exposing with an interference pattern of Hd-Cd laser [Fig. 3
(A)].

Next, by development, a resist mask 32b in a grid pattern is produced [FIG. 3 (b)]. And
Using this resist mask 32b, the InP substrate 31 is etched by a chemical etching method to form a diffraction grating on the surface of the InP substrate 31 [FIG. 3 (c)].

The period Λ of this diffraction grating has a laser wavelength of λ
_{Let L be} the incident angle of the laser light on the surface of the InP substrate, which is given by equation (1). By changing the incident angle θ, the period Λ of the diffraction grating is adjusted.

Λ = λ _L / 2 sin θ (1) By liquid phase epitaxy on the diffraction grating thus formed
InGaAsP buffer layer, active layer, InP clad layer, InGaAs
After continuously growing the P cap layer, the growth layer is mesa-etched in a stripe shape having a predetermined width in the direction perpendicular to the diffraction grating, and n-type or p-type InP is embedded in the portion removed by etching. A distributed feedback laser is formed.

[0008]

By the way, as described above, in the conventional example, the diffraction grating is formed in the atmosphere, and at this time, the adherence of oxide impurities and the like is likely to occur on the substrate surface. However, there is a problem in that the epitaxial growth film formed by the film forming process in vacuum is likely to have defects and the crystallinity of the thin film crystal is deteriorated. In addition, the manufacturing apparatus having the configuration of the conventional example has a problem that it is a complicated process divided into two processes, that is, a process performed in the air and a process performed in vacuum.

The present invention has been made to solve these problems, and provides a semiconductor manufacturing apparatus capable of simplifying the manufacturing process and manufacturing a highly reliable laser device having improved characteristics. With the goal.

[0010]

In order to achieve the above object, the semiconductor manufacturing apparatus of the present invention outputs a laser beam for forming interference fringes on the surface of a substrate placed in a growth chamber. A single laser light source, a beam splitter that divides the laser light output from the laser light source into laser beam bundles in at least two directions, and a laser beam bundle divided in each direction on the surface of the substrate at a predetermined incident angle. Is provided in each optical path and an epitaxial growth apparatus for forming an epitaxial growth film of a compound semiconductor on the substrate surface on which the interference fringes are formed is characterized.

[0011]

The laser light output from the single laser light source is divided into two or more laser beam bundles, and each laser beam bundle is guided onto the surface of the substrate at a predetermined incident angle by a mirror provided in each optical path thereof. An interference fringe is formed on the substrate surface due to the interference of the plurality of laser beam bundles.

In addition, the organometallic gas is excited and easily decomposed in the portion of the interference fringes on the surface of the substrate which is irradiated with the laser light. Therefore, the growth rate of the film is different between the part irradiated with the laser light and the part not irradiated with the laser light, and a growth film having unevenness in the diffraction pattern along the interference fringes on the substrate surface is formed.

[0013]

1 is a block diagram of a semiconductor manufacturing apparatus according to an embodiment of the present invention. Hereinafter, description will be given with reference to the drawings.

The semiconductor manufacturing apparatus of the embodiment of the present invention is a MOC.
It is composed of a VD (Metal-Organic CVD) device and a laser interference exposure device for forming a diffraction grating pattern on the substrate surface.

First, in the growth chamber 1, an InP substrate 5 and a heater 6 for heating the InP substrate 5 are arranged. In addition, the optical windows 3 are respectively provided on the two opposite side surfaces of the growth chamber 1.
a and 3b are provided, and the laser light output from the laser interference exposure apparatus enters the growth chamber 1 through the optical windows 3a and 3b. In addition, a gas supply system 8 is provided near the growth chamber 1, and trimethylindium (TMI), phosphine (PH ₃ ), and H ₂ gas for diluting TMI are used as organometallic gases, respectively. Thus, the gas is introduced into the growth chamber 1 at an appropriate ratio through the gas introduction port 7. Further, an exhaust system 9 for evacuating the growth chamber 1 is provided.

On the other hand, in the laser interference exposure apparatus, a laser light source 2 for outputting a laser beam, a beam splitter 4 for splitting the laser beam into a beam bundle of two directions, and each laser beam are guided onto an InP substrate 5. each optical path, the spatial filter 10a, 10b, afocal lens 11a, 11b and a mirror 12a _1, 12a _2, 12b are arranged in this order. This laser interference exposure apparatus is configured such that interference fringes are formed on the InP substrate 5 by the laser light that is incident on the InP substrate 5 via each optical path, and the distance between the interference fringes is required. The laser incident angle, wavelength, etc. are adjusted so as to match the grating spacing of the diffraction grating.

Next, a method of manufacturing the distributed feedback laser shown in FIG. 2 using the semiconductor manufacturing apparatus of the embodiment of the present invention having the above structure will be described. In the growth chamber 1, an InP substrate 5 for forming a distributed feedback laser is held by a substrate holder (not shown) provided in the growth chamber 1, and the inside of the growth chamber 1 is exhausted by an exhaust system 9. Evacuate.

Next, the laser light output from the single laser light source 2 is split by the beam splitter 4 into a bidirectional beam bundle. Of these beam bundles, one of the beam bundles is the spatial filter 10a and the afocal lens 11a.
Then, the light is adjusted to a predetermined incident angle by the mirrors 12a ₁ and 12a ₂ and then incident on the InP substrate 5. Similarly, the other beam bundle passes through the spatial filter 10b and the afocal lens 11b, is adjusted to a predetermined incident angle by the mirror 12b, and is incident on the InP substrate 5. These beam bundles enter through the optical windows 3b and 3a, respectively,
The laser incident angle and the wavelength are set in advance so that interference fringes are generated, but match the required grating spacing of the diffraction grating.

Next, the temperature of the InP substrate 5 is maintained at 500 ° C. by the heater 6, and H ₂ gas, TMI, and PH ₃ gas are supplied in an appropriate ratio from the gas supply system 8 through the gas inlet 7 to the inside of the growth chamber 1. To introduce. TMI is appropriately diluted in the growth chamber 1 with H ₂ gas. And these gases are the InP substrate 5
A growth film is formed by reaching the top. MOCV like this
In the method D, the growth film is usually formed while the substrate temperature is kept at 600 to 700 ° C., but in the embodiment of the present invention, the growth film is formed at a relatively low temperature of about 500 ° C. That is, under this condition, the organometallic gas is difficult to decompose, so that the growth rate of the growth film decreases. However, in the portion of the surface of the InP substrate 5 irradiated with the laser beam, the organometallic gas is excited and easily decomposed, and the photochemical reaction thereof rapidly increases the growth rate of the growth film. It is possible to form a growth film in which irregularities are repeated at intervals, and it is possible to obtain a desired diffraction grating.

On the diffraction grating obtained by the above method, an InGaAsP buffer layer, an active layer, an InP clad layer, and an InGaAsP cap layer are continuously grown as in the conventional example. In this step, the substrate temperature of the InP substrate 5 is normally 600 to 700.
Return to ℃ and perform. After that, the growth layer is further mesa-etched in a stripe shape having a predetermined width in the direction perpendicular to the diffraction grating, and n-type or p-type In
A distributed feedback laser is completed by embedding P.

The steps of forming the diffraction grating pattern on the surface of the substrate and the subsequent step of continuously forming the growth film are all performed continuously with the InP substrate 5 placed in the growth chamber 1. In addition, contamination such as adhesion of impurities on the InP substrate 5 does not occur, and the crystallinity of the obtained thin film is good.

[0022]

As described above, according to the present invention,
Since the MOCVD apparatus is provided with the laser interference exposure apparatus and the diffraction pattern of the interference fringes generated by guiding the laser light having the predetermined wavelength and the incident angle to the surface of the substrate is formed, the pattern of this diffraction grating and the subsequent The growth film can be continuously formed in the growth chamber, and the crystallinity of the formed thin film crystal is improved. Therefore, the characteristics of the obtained laser device are improved and the reliability is improved. Furthermore, the photolithography process and the etching process that have been conventionally performed are not required as the process of forming the diffraction grating pattern,
The manufacturing process can be simplified.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a schematic diagram showing the structure of an InGaAsP-InP distributed feedback laser.

FIG. 3 is a diagram for explaining a method of manufacturing a diffraction grating with a conventional apparatus over time.

[Explanation of symbols]

1 ... Growth chamber 2 ... Laser light source 3a, 3b ... Optical window 4 ... Beam splitter 5 ... InP substrate 6 ... Heater 7 ... Gas introduction mouth 8 ... gas supply source 10a, 10b ... spatial filter 11a, 11b ... afocal lens 12a _1, 12a _2, 12b ···· mirror

Claims (1)

[Claims] 1. A single laser light source that outputs laser light for forming interference fringes on the surface of a substrate placed in a growth chamber, and a laser light output from the laser light source in at least two directions. A beam splitter that divides into a laser beam bundle, and a plurality of mirrors that cause the laser beam bundle divided in each direction to be incident on the substrate surface at a predetermined incident angle in each optical path, and the substrate on which the interference fringes are formed A semiconductor manufacturing apparatus comprising an epitaxial growth apparatus for forming an epitaxial growth film of a compound semiconductor on a surface.