JP2012124361A - Manufacturing method of semiconductor optical element and semiconductor optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a leak current from occurring when a separation groove provided to electrically separate a waveguide part included in a semiconductor optical element of PBH structure is not formed appropriately.SOLUTION: A manufacturing method of a semiconductor optical element comprises: a step of forming a mesa stripe-shaped active layer 12 on an n-type InP substrate 10; a step of forming an Ru-InP layer 14 up to a higher position than the active layer 12 on both sides of the active layer 12; a step of forming a silicon oxide film 18 in a separation groove formation region 20 provided on a surface of the Ru-InP layer 14; and a step of forming a P-InP layer 16 by crystal growth on the Ru-InP layer 14 on which the silicon oxide film 18 was formed.

Description

  The present invention relates to a method for manufacturing a semiconductor optical device and a semiconductor optical device.

  One of the structures of a semiconductor optical device (semiconductor laser) is a PBH structure (Planer Buried Heterostructure) (see, for example, Patent Document 1 below).

  Conventionally, in manufacturing a semiconductor optical device having a PBH structure, a separation groove for electrically separating a waveguide provided in the semiconductor optical device is formed by, for example, the procedure shown in FIGS. 7 to 10 below. It was.

  That is, as shown in FIG. 7, in the conventional semiconductor optical device 2 having the PBH structure, the active layer 12 and the buried layer (Ru—InP layer 14) are formed on the n-type InP substrate 10 and then buried. A p-type cladding layer (P-InP layer 16) was formed on the buried layer.

  Further, as shown in FIG. 8, the surface of the formed P-InP layer 16 is masked with a resist agent 100 except for the etching portion, and then the P-InP layer 16 is etched by Br-based wet etching. A separation groove was formed. FIG. 9 shows the semiconductor optical device 2 in a state in which the P-InP layer 16 is etched to form a separation groove.

  Then, as shown in FIG. 10, a passivation film 24 (protective film) is formed on the isolation trench formed by etching, and then an electrode 26 is deposited to manufacture a semiconductor optical device 2 having a PBH structure. It was.

JP 2000-0777780 A

  When the semiconductor optical device 2 having the PBH structure is manufactured by the steps shown in FIGS. 7 to 10, the etching depth of the P-InP layer 16 is deep to the Ru-InP layer 14 as shown in FIG. It has been difficult to control the depth of the separation groove, for example, it has been reached or conversely stopped at the P-InP layer 16. Further, as shown in FIG. 9, by forming the separation groove by etching, a vertical surface is formed in the separation groove as shown in FIG. 10, and the passivation film 24 and the electrode 26 are formed on the vertical surface. Insufficient formation may cause disconnection and leakage current.

  One of the objects of the present invention is that a leakage current is generated due to an improper formation of an isolation groove provided for electrical isolation of a waveguide portion included in a semiconductor optical device having a PBH structure. An object of the present invention is to provide a method of manufacturing a semiconductor optical device and a semiconductor optical device that can prevent the occurrence of the semiconductor optical device.

  In order to achieve the above object, a method of manufacturing a semiconductor optical device according to the present invention includes a step of forming a mesa stripe-shaped active layer on an n-type InP substrate, and the active layer on both sides of the active layer. Forming a buried layer up to a high position; forming an oxide film mask in an isolation groove forming region provided on the surface of the buried layer; and on the buried layer on which the oxide film mask is formed. And a step of crystal-growing a conductive clad layer.

  In one aspect of the present invention, the method of manufacturing a semiconductor optical device includes a step of removing the oxide film mask after the formation of the conductive type cladding layer, the separation groove forming region, and the separation groove. Forming a passivation film on the conductive clad layer formed around the formation region, and forming an electrode on the conductive clad layer after the passivation film is formed And further included.

  In one embodiment of the present invention, the buried layer is made of indium phosphide doped with ruthenium, the oxide film mask is made of a silicon oxide film, and the conductive cladding layer is made of p-type. It is assumed to be composed of indium phosphide.

  The semiconductor optical device according to the present invention is manufactured by the method for manufacturing a semiconductor optical device.

  Further, a semiconductor optical device according to the present invention includes a mesa stripe-shaped active layer formed on an n-type InP substrate, a buried layer formed on both sides of the active layer up to a position higher than the active layer, A conductive-type cladding layer formed in a region excluding the separation groove forming region provided on the surface of the buried layer, wherein the conductive-type cladding layer extends from the separation groove formation region to the conductive-type cladding. It has the surface along the growth direction of the crystal which comprises a layer, It is characterized by the above-mentioned.

  Further, a semiconductor optical device according to the present invention includes a mesa stripe-shaped active layer formed on an n-type InP substrate, a buried layer formed on both sides of the active layer up to a position higher than the active layer, A conductive clad layer formed on the buried layer and having a separation groove, wherein the bottom of the separation groove is on the surface of the buried layer.

  According to one aspect of the present invention, a leakage current is generated due to an improper formation of a separation groove provided for electrical isolation of a waveguide portion included in a semiconductor optical device having a PBH structure. Can be prevented.

It is a figure which shows an example of sectional drawing of the semiconductor optical element in 1 process of the manufacturing method which concerns on this embodiment. It is a figure which shows an example of sectional drawing of the semiconductor optical element in the process following FIG. It is a figure which shows an example of sectional drawing of the semiconductor optical element in the process following FIG. It is a figure which shows an example of sectional drawing of the semiconductor optical element in the process following FIG. It is a figure which shows an example of sectional drawing of the semiconductor optical element in the process following FIG. It is a figure which shows an example of sectional drawing of the semiconductor optical element in the process following FIG. It is a figure which shows an example of sectional drawing of the semiconductor optical element in 1 process of the conventional manufacturing method. It is a figure which shows an example of sectional drawing of the semiconductor optical element in the process following FIG. It is a figure which shows an example of sectional drawing of the semiconductor optical element in the process following FIG. It is a figure which shows an example of sectional drawing of the semiconductor optical element in the process following FIG.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments (hereinafter referred to as embodiments) for carrying out the invention will be described with reference to the drawings.

  FIGS. 1 to 6 are views for explaining steps in the method of manufacturing the semiconductor optical device 1 according to this embodiment. 1 to 6 are cross-sectional views of the semiconductor optical device 1 having a PBH structure in each step.

  The semiconductor optical device 1 shown in FIG. 1 is provided on an n-type InP substrate 10 (InP: indium phosphide) in a mesa stripe shape and on both sides of the active layer 12 up to a position higher than the active layer 12. This is a semiconductor optical device 1 in which a Ru—InP layer 14 that is a buried layer is formed. The active layer 12 may be composed of InGaAsP (indium gallium arsenide phosphorus), and the active layer 12 may include a plurality of active layer regions 13 as illustrated. At this time, by changing the composition ratio of InGaAsP between some active layer regions 13 and other active layer regions 13, some active layer regions 13 may function as waveguides. The buried layer may be configured as a high-resistance InP layer doped with ruthenium (Ru).

  The manufacturing process up to the semiconductor optical device 1 shown in FIG. 1 may be performed using a known process. For example, after the active layer 12 composed of InGaAsP is stacked on the n-type InP substrate 10, only the central stripe region of the stacked active layer 12 is left, and the active layer 12 disappears on both sides. It is good also as removing by an etching. After forming the mesa stripe-shaped active layer 12 in this way, a buried layer composed of Ru—InP may be formed by crystal growth (epitaxial growth) in regions adjacent to the active layer 12.

Next, as shown in FIG. 2, a mask of silicon oxide film 18 (SiO ₂ ) is formed in the isolation trench formation region 20 provided on the surface of the Ru—InP layer 14. The isolation groove forming region 20 in this embodiment is a groove provided in the upper cladding layer (p-type cladding layer) in order to electrically isolate the active layer 12 in the semiconductor optical device 1 having the PBH structure. This is the bottom area. The separation groove forming regions 20 may be provided on the left and right with the active layer 12 as the center. The mask formed in the separation groove forming region 20 may be a mask composed of another material such as SiN.

  Next, as shown in FIG. 3, a p-type InP layer (P) is formed on the Ru-InP layer 14 with the silicon oxide film 18 provided in the isolation groove forming region 20 on the surface of the Ru—InP layer 14. -Crystal growth of InP layer 16). For the crystal growth, a metal organic chemical vapor deposition (MOCVD) method may be used.

  As shown in FIG. 3, no crystal grows in the portion of the Ru-InP layer 14 where the silicon oxide film 18 is provided, and the portion adjacent to the silicon oxide film 18 of the P-InP layer 16 has no P-InP. A slope is formed along the crystal growth direction.

  Next, as shown in FIG. 4, after the P-InP layer 16 is grown, the silicon oxide film 18 is removed. As a result, the bottom of the separation groove formed in the P-InP layer 16 coincides with the surface of the Ru-InP layer 14. In this embodiment, the separation groove is a portion composed of the slope 22 of the P-InP layer 16 adjacent to the separation groove formation region 20 with the separation groove formation region 20 of the Ru-InP layer 14 as the bottom. Say.

  Next, as shown in FIG. 5, after removing the silicon oxide film 18, the periphery including the isolation trench is covered with a passivation film 24. An insulating film may be used for the passivation film 24. The passivation film 24 may be formed around each separation groove except for the periphery around the active layer 12.

  Further, as shown in FIG. 6, an electrode 26 (P-type electrode) is formed on the surface of the P-InP layer 16 on which the passivation film 24 is formed. For example, the electrode 26 may be formed by vapor deposition.

  In the semiconductor optical device 1 having the PBH structure formed by the above process, the slope 22 of the separation groove formed in the P-InP layer 16 is an angle (for example, about 45 degrees) along the P-InP crystal orientation (111 plane). Therefore, the slope 22 of the separation groove is not steep, and the thickness of the passivation film 24 and the electrode 26 provided in the separation groove is not uneven. Therefore, disconnection of the electrode 26 is less likely to occur.

  In the semiconductor optical device 1 having the PBH structure formed by the above steps, the separation groove depth is constant because the bottom of the separation groove formed in the P-InP layer 16 coincides with the surface of the Ru-InP layer 14. It becomes. Therefore, compared with the case where the P-InP layer 16 is etched to form the separation groove, there is no residue of the P-InP layer 16 and the Ru-InP layer 14 is not scraped. Can be deterred.

  Further, according to the method for manufacturing the semiconductor optical device 1 described above, the shape of the separation groove does not vary between lots in the wafer surface as compared with the case where the separation groove is formed by etching the P-InP layer 16. The semiconductor optical device 1 with stable quality can be provided.

  In addition, this invention is not limited to said embodiment, Of course, a various change, deformation | transformation, or substitution is possible by those skilled in the art who have the normal knowledge of this field | area.

  DESCRIPTION OF SYMBOLS 1 Semiconductor optical device, 2 Semiconductor optical device (conventional), 10 n-type InP substrate, 12 Active layer, 13 Active layer area | region, 14 Ru-InP layer, 16 P-InP layer, 18 Silicon oxide film, 20 Separation groove formation area , 22 slope, 24 passivation film, 26 electrodes, 100 resist agent.

Claims (6)

forming a mesa stripe active layer on an n-type InP substrate;
Forming a buried layer on both sides of the active layer to a position higher than the active layer;
Forming an oxide film mask in a separation groove forming region provided on the surface of the buried layer;
Forming a conductive clad layer on the buried layer on which the oxide mask is formed by crystal growth;
The manufacturing method of the semiconductor optical element characterized by the above-mentioned. Removing the oxide mask after the conductive cladding layer is formed;
Forming a passivation film on the separation groove forming region and the conductive clad layer formed around the separation groove formation region;
Forming an electrode on the conductive clad layer after the passivation film is formed;
The method of manufacturing a semiconductor optical device according to claim 1, further comprising: The buried layer is made of indium phosphide doped with ruthenium,
The oxide film mask is composed of a silicon oxide film,
The method of manufacturing a semiconductor optical device according to claim 1, wherein the conductive clad layer is made of p-type indium phosphide.   A semiconductor optical device manufactured by the method for manufacturing a semiconductor optical device according to claim 1. a mesa stripe-shaped active layer formed on an n-type InP substrate;
A buried layer formed up to a position higher than the active layer on both sides of the active layer;
A conductive clad layer formed in a region excluding the separation groove forming region provided on the surface of the buried layer, and
The conductive-type cladding layer has a surface along a growth direction of a crystal constituting the conductive-type cladding layer from the isolation groove forming region. a mesa stripe-shaped active layer formed on an n-type InP substrate;
A buried layer formed up to a position higher than the active layer on both sides of the active layer;
A conductive-type cladding layer formed on the buried layer and having a separation groove;
The bottom of the said isolation groove exists on the surface of the said embedding layer. The semiconductor optical element characterized by the above-mentioned.

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