JP2010014495A - Optical gyro sensor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical gyro sensor and its manufacturing method capable of integrating highly accurately an optical waveguide and an optical amplifier on a semiconductor substrate. <P>SOLUTION: This optical gyro sensor is equipped with the semiconductor substrate 1; the optical amplifier 10 arranged on the semiconductor substrate 1, and having an output surface 11 and an output surface 12 respectively; the optical waveguide 20 having each end face close to the output surface 11 and the output surface 12 respectively, and arranged on the semiconductor substrate 1 so as to constitute a ring-shaped optical path together with the optical amplifier 10, for propagating first laser light L1 output from the output surface 11 and second laser light L2 output from the output surface 12 in each different circulation direction; a detection path 30 arranged on the semiconductor substrate 1, to which each part of the first laser light L1 and the second laser light L2 is transferred from the optical waveguide 20; and a signal detector 40 for detecting a beat signal generated by coupling each part of the first laser light L1 and the second laser light L2 transferred to the detection path 30. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical gyro sensor, and more particularly to an optical gyro sensor in which an optical amplifier and an optical waveguide are arranged on the same semiconductor substrate, and a method for manufacturing the same.

  There are various types of angular velocity detection devices (gyro sensors) that detect the angular velocity of a rotating object, depending on the operating principle, structure, drive system, and the like. For example, an optical gyro sensor that detects an angular velocity using a frequency difference between two laser beams traveling in opposite directions in an optical waveguide arranged in a ring shape has been developed.

In response to demands for lower power consumption, smaller size, and lower price of optical gyro sensors, optical amplifiers on a semiconductor substrate, optical waveguides arranged in a ring shape, and laser signals propagating through the optical waveguides are extracted to generate beat signals. A method of integrating an optical coupler to be observed has been proposed (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2008-2954

  However, in the optical gyro sensor described in Patent Document 1, after an optical waveguide is formed on a semiconductor substrate, an optical amplifier that outputs laser light to the optical waveguide is mounted on the semiconductor substrate and integrated. For this reason, it is difficult to mount an optical amplifier with a high accuracy with respect to the position of the optical waveguide, and there is a gap between the optical amplifier and the optical waveguide, or the center of the optical amplifier mode field and the center of the optical waveguide. There was a problem that did not match.

  In view of the above problems, an object of the present invention is to provide an optical gyro sensor capable of highly accurately integrating an optical waveguide and an optical amplifier on a semiconductor substrate, and a method for manufacturing the same.

  According to one aspect of the present invention, (a) a semiconductor substrate, (b) an optical amplifier disposed on the semiconductor substrate and having first and second output surfaces, respectively, (c) first and second The first laser beam output from the first output surface and the second output surface are arranged on the semiconductor substrate so as to form a ring-shaped optical path together with the optical amplifier having end faces in close contact with the output surface. An optical waveguide in which the output second laser light propagates in different circumferential directions; and (d) a detection path that is disposed on the semiconductor substrate and in which a part of each of the first and second laser lights moves from the optical waveguide; (E) An optical gyro sensor provided with a signal detector for detecting a beat signal generated by combining a part of each of the first and second laser beams transferred to the detection path is provided.

  According to another aspect of the present invention, (b) placing an optical amplifier having first and second output surfaces on a semiconductor substrate; and (b) close to the first and second output surfaces, respectively. The first laser beam output from the first output surface and the second output from the second output surface are disposed on the semiconductor substrate so as to form a ring-shaped optical path together with the optical amplifier. A step of forming an optical waveguide in which laser light propagates in different circumferential directions; and (c) a detection path through which a part of each of the first and second laser lights propagates, and an interval between the first and second optical waveguides. Forming a part of the laser light on the semiconductor substrate at a distance that shifts from the optical waveguide. Is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the optical gyro sensor which can integrate an optical waveguide and an optical amplifier on a semiconductor substrate with high precision, and its manufacturing method can be provided.

  Next, first and second embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  Further, the following first and second embodiments exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention is a component part. The material, shape, structure, arrangement, etc. are not specified below. The technical idea of the present invention can be variously modified within the scope of the claims.

(First embodiment)
As shown in FIG. 1, an optical gyro sensor according to a first embodiment of the present invention includes a semiconductor substrate 1, an optical amplifier 10 disposed on the semiconductor substrate 1, and having an output surface 11 and an output surface 12, respectively. The first laser beam L1 output from the output surface 11 is disposed on the semiconductor substrate 1 so as to form a ring-shaped optical path together with the optical amplifier 10 having end faces in close contact with the output surface 11 and the output surface 12, respectively. And the second laser beam L2 output from the output surface 12 is disposed on the semiconductor substrate 1 and the optical waveguide 20 in which the second laser beam L2 propagates in different circumferential directions, and a part of each of the first laser beam L1 and the second laser beam L2 A detection path 30 that moves from the optical waveguide 20 and a signal detector 40 that detects a beat signal that is generated when a part of each of the first laser light L1 and the second laser light L2 that have moved to the detection path 30 is combined. Obtain.

  In the optical gyro sensor shown in FIG. 1, the optical amplifier 10 and the optical waveguide 20 form a ring-shaped optical path. Specifically, one end face of the optical waveguide 20 is in close contact with the output face 11 of the optical amplifier 10, and the other end face of the optical waveguide 20 is in close contact with the output face 12 of the optical amplifier 10. Then, the first laser light L 1 output from the output surface 11 of the optical amplifier 10 propagates through the optical waveguide 20 and enters the optical amplifier 10 from the output surface 12. The second laser light L2 output from the output surface 12 of the optical amplifier 10 propagates through the optical waveguide 20 and enters the optical amplifier 10 from the output surface 11. As will be described later, the first laser light L1 and the second laser light L2 input to the optical amplifier 10 are amplified by the optical amplifier 10 and then output to the optical waveguide 20. Hereinafter, a case where the first laser light L1 propagates in the clockwise direction in the optical waveguide 20 and the second laser light L2 propagates in the counterclockwise direction in the optical waveguide 20 will be described as an example.

  In the light extraction region A shown in FIG. 1, a part of each of the first laser light L <b> 1 and the second laser light L <b> 2 moves from the optical waveguide 20 to the light extraction unit 301 of the detection path 30. In order to shift a part of the first laser beam L1 and the second laser beam L2, the light extraction unit 301 and the optical waveguide 20 are distances at which a part of the first laser beam L1 and the second laser beam L2 respectively shift ( Hereinafter, they are arranged in parallel over a certain length (hereinafter referred to as “light extraction length”) with a “light extraction distance”. The light extraction length and light extraction according to the refractive index of the region where the first laser light L1 and the second laser light L2 propagate in the optical waveguide 20 and the detection path 30, the wavelengths of the first laser light L1 and the second laser light L2, and the like. By setting the distance, for example, about 1% to 10% of each of the first laser beam L1 and the second laser beam L2 moves from the optical waveguide 20 to the detection path 30.

  The first detection laser light L1a, in which a part of the first laser light L1 has moved from the optical waveguide 20 to the detection path 30, propagates from the light extraction region A in the counterclockwise direction. On the other hand, the second detection laser light L2a in which a part of the second laser light L2 has moved from the optical waveguide 20 to the detection path 30 propagates from the light extraction region A to the detection path 30 in the clockwise direction.

  The region where the first detection laser beam L1a propagates in the detection path 30 and the region where the second detection laser beam L2a propagates are adjacently arranged in parallel in the signal detection region B at an interval of distance w. In the signal detection region B, the first detection laser beam L1a and the second detection laser beam L2a propagate in the same direction.

  The distance w between the detection paths 30 in the signal detection region B is set to a distance at which a part (for example, about 50%) of each of the first detection laser light L1a and the second detection laser light L2a moves to the adjacent detection path 30. Is done. The distance w is set to, for example, about several times the wavelength of the first detection laser beam L1a or the second detection laser beam L2a, or less. That is, the detection path 30 in the signal detection region B functions as an optical coupler.

  As a result, the first detection laser beam L1a and the second detection laser beam L2a are multiplexed in the signal detection region B. When there is a frequency difference between the frequency of the first detection laser light L1a and the frequency of the second detection laser light L2a, the detection unit 302 of the detection path 30 included in the signal detection region B performs the first A beat signal in which the detection laser beam L1a and the second detection laser beam L2a are superimposed is generated.

  The beat signal generated in the detection unit 302 is detected from the detection unit 302 by the signal detector 40 disposed in the traveling direction of the second detection laser light L2a, that is, at the end of the detection path 30. For the signal detector 40, for example, a light receiving element such as a photodiode or a phototransistor can be employed.

  When the semiconductor substrate 1 is rotated clockwise or counterclockwise in the circumferential direction of the optical waveguide 20, the optical path length of the optical waveguide 20 is changed between the first laser light L1 and the second laser light L2 by the Sagnac effect. Seen differently, this apparent difference in optical path length causes a frequency difference between the first laser beam L1 and the second laser beam L2. This frequency difference is observed as the light intensity of the beat signal between the first detection laser beam L1a and the second detection laser beam L2a. Therefore, the angular velocity of the semiconductor substrate 1 can be calculated using the change in the light intensity of the beat signal generated in the detection unit 302.

  In the optical gyro sensor shown in FIG. 1, the beat signal detected by the signal detector 40 is output from the signal detector 40 to the angular velocity calculation circuit 50 as an electric signal. The angular velocity calculation circuit 50 calculates the angular velocity of the semiconductor substrate 1 using the light intensity of the beat signal.

  Although FIG. 1 shows the case where the signal detector 40 and the angular velocity calculation circuit 50 are arranged outside the semiconductor substrate 1, the signal detector 40 and the angular velocity calculation circuit 50 may be formed on the semiconductor substrate 1. That is, the optical gyro sensor shown in FIG. 1 can be reduced in size by integrating the optical gyro sensor into one chip.

  In FIG. 1, illustration of electrode terminals arranged on the semiconductor substrate 1 for driving the optical amplifier 10 and wirings connecting the electrode terminals and the optical amplifier 10 are omitted.

  The optical amplifier 10 shown in FIG. 1 has a function of amplifying the first laser light L1 and the second laser light L2 that form a ring-shaped optical path together with the optical waveguide 20 and go around the optical waveguide 20 and return to the optical amplifier 10. Various elements can be used as long as they have elements. For example, a semiconductor optical amplifier (SOA) or the like can be used for the optical amplifier 10.

  An example in which SOA is used for the optical amplifier 10 is shown in FIG. FIG. 2 is a cross-sectional view taken along the II direction of FIG. The SOA shown in FIG. 2 has a structure in which a lower clad layer 102, an active layer 103, and an upper clad layer 104, which are part of the semiconductor substrate 1, are laminated between a lower electrode 101 and an upper electrode 105. By flowing a current between the lower electrode 101 and the upper electrode 105, the SOA is in an inverted distribution state. The first laser light L1 and the second laser light L2 respectively output from the output surface 11 and the output surface 12 of the optical amplifier 10 to the optical waveguide 20 circulate around the optical waveguide 20 and then from the output surface 12 and the output surface 11 respectively. Input to the optical amplifier 10. When the first laser beam L1 and the second laser beam L2 are input to the SOA in the inverted distribution state, electrons and holes are recombined in the active layer 103, and dielectric emission occurs. As a result, the input first laser beam L1 and second laser beam L2 are amplified and output from the output surface 11 and the output surface 12, respectively. In the example shown in FIG. 2, in order to narrow the current path, the insulating film 110 is disposed in a part between the upper clad layer 104 and the upper electrode 105 so that the upper clad layer 104 and the upper electrode 105 are in contact with each other. The area is limited.

  The active layer 103 includes, for example, a group III element such as aluminum (Al), gallium (Ga), and indium (In) and a group III element such as nitrogen (N), phosphorus (P), and arsenic (As). A -V group compound semiconductor or the like can be used. The lower cladding layer 102 and the upper cladding layer 104 are layers for confining the first laser beam L1 and the second laser beam L2 generated in the active layer 103 in the active layer 103. Therefore, a material having a band gap larger than that of the active layer 103 is selected for the lower cladding layer 102 and the upper cladding layer 104.

  When the SOA is such that electrons are injected from the lower electrode 101 and holes are injected from the upper electrode 105, that is, when the lower cladding layer 102 is an n-type cladding layer and the upper cladding layer 104 is a p-type cladding layer, The lower cladding layer 102, the active layer 103, and the upper cladding layer 104 are configured as follows.

That is, the lower cladding layer 102 has a GaAs film with a thickness of about 100 nm doped with an n-type impurity such as silicon (Si) at a carrier concentration of about 1 × 10 ¹⁸ cm ⁻³ , and Si with 8 × 10 ¹⁷ cm. A laminated body with an Al _0.3 Ga _0.7 As film having a thickness of about 2500 nm doped with a carrier concentration of about ⁻³ can be employed. As the n-type impurity, selenium (Se), tellurium (Te), or the like can be used in addition to Si.

The active layer 103 includes a GaAs film with a thickness of about 60 nm as a guide layer, an In _0.2 Ga _0.8 As film with a thickness of about 4.5 nm as a well layer, a GaAs layer with a thickness of about 6 nm as a barrier layer, A laminated body in which GaAs films with a thickness of about 60 nm are sequentially laminated as the guide layer can be employed.

The upper cladding layer 104 includes an Al _0.3 Ga _0.7 As film having a thickness of about 1700 nm doped with a p-type impurity such as zinc (Zn) at a carrier concentration of about 8 × 10 ¹⁷ cm ⁻³ , and Zn of 3 A laminated body with a GaAs film having a thickness of about 250 nm doped with a carrier concentration of about 5 × 10 ¹⁹ cm ⁻³ can be employed. Note that the Zn-doped GaAs film is disposed as a contact layer for reducing the electrical resistance between the upper cladding layer 104 and the upper electrode 105. As the p-type impurity, beryllium (Be), magnesium (Mg), carbon (C), or the like can be employed in addition to Zn.

  In order to form a ring-shaped optical path by the optical waveguide 20 and the optical amplifier 10, it is preferable that the first laser beam L1 and the second laser beam L2 are less reflected on the output surfaces 11 and 12. For this purpose, it is effective to cover the output surfaces 11 and 12 of the optical amplifier 10 with an antireflection (AR) film 120 as shown in FIG. As the AR film 120, a laminated body of a plurality of dielectric films having different refractive indexes can be adopted. The material and thickness of the AR film 120 are selected according to the wavelengths of the first laser light L1 and the second laser light L2, the refractive index of the active layer 103, and the like.

  In the example shown in FIG. 2, a part of the semiconductor substrate 1 is the lower cladding layer 102 of the optical amplifier 10. For this reason, the semiconductor substrate 1 is selected according to the material constituting the optical amplifier 10. For example, the semiconductor substrate 1 may be a gallium arsenide (GaAs) substrate, an indium phosphide (InP) substrate, or the like. Note that an extraction electrode for applying a voltage to the lower electrode 101 and the upper electrode 105 from the outside is disposed on the semiconductor substrate 1, but this extraction electrode is not shown in FIGS. 1 and 2.

  As shown in FIG. 2, the optical waveguide 20 can employ a laminated structure including a core layer 201 and a clad layer 202 surrounding the core layer 201. In this case, in order to confine the first laser light L1 and the second laser light L2 in the core layer 201 of the optical waveguide 20, a material having a refractive index lower than that of the core layer 201 is selected for the cladding layer 202. For example, the difference in relative refractive index between the cladding layer 202 and the core layer 201 is set to about 1.5%. The width and thickness of the core layer 201, the thickness of the cladding layer 202, and the like are set according to the wavelengths of the first laser light L1 and the second laser light L2, the refractive indexes of the core layer 201 and the cladding layer 202, and the like. The

  As shown in FIG. 2, in the optical waveguide 20, the core layer 201 is disposed in close contact with the output surface 11 of the optical amplifier 10, and a part of the upper portion of the core layer 201 includes an end portion of the optical amplifier 10 including the output surface 11. Covers the top surface. Although not shown, the output surface 12 of the optical amplifier 10 facing the output surface 11 is also in close contact with the core layer 201 in the same manner. That is, there is no gap between the optical waveguide 20 and the optical amplifier 10.

  The material of the optical waveguide 20 is not limited as long as it is a substance that forms a waveguide through which light propagates, but a polymer, resin, glass, semiconductor, or the like can be used for the optical waveguide 20. In particular, a polymer typified by a polymerized polymer organic compound can suppress damage due to heat treatment in a subsequent process after the formation of the optical waveguide 20 by selecting a material having a firing temperature of a certain level or higher and heat resistance. It is suitable for the material of the optical waveguide 20.

  As will be described later, the optical waveguide 20 is formed after the optical amplifier 10 is disposed on the semiconductor substrate 1. For this reason, the material of the optical waveguide 20 is selected so that the optical amplifier 10 is not damaged by the heat treatment in the process of forming the optical waveguide 20. For example, by adopting a polymer having a baking temperature of about 350 ° C. for the optical waveguide 20, even when the SOA in which the III-V compound semiconductor is laminated is used for the optical amplifier 10, the heat treatment in the optical waveguide 20 formation process. The damage of the optical amplifier 10 due to can be suppressed. Specifically, polyimide or the like can be used for the optical waveguide 20.

  In addition, it is preferable that the optical waveguide 20 be formed of a material that does not absorb the first laser light L1 and the second laser light L2. Accordingly, the optical gyro sensor shown in FIG. 1 has a lower power than the optical gyro sensor in which the optical waveguide 20 through which the first laser light L1 and the second laser light L2 propagate is formed of the same material as the active layer 103 of the SOA. Can be driven by.

  The optical amplifier 10 and the optical waveguide 20 are arranged on the semiconductor substrate 1 so that the center of the mode field of the optical amplifier 10 and the center of the core layer 201 of the optical waveguide 20 coincide. However, the optical amplifier 10 and the optical waveguide 20 are arranged so as to suppress the influence of the reflection of the first laser light L1 and the second laser light L2 at the interface between the active layer 103 and the core layer 201 on the performance of the optical gyro sensor. There is a need. For example, the central axes in the light propagation direction of the active layer 103 and the central axes in the light propagation direction of the optical waveguide 20 are arranged at an angle of several degrees so that they do not coincide with each other. Is preferred.

  Similarly to the optical waveguide 20, the detection path 30 can employ a laminated structure including a core layer 201 and a clad layer 202 disposed around the core layer 201. For this reason, the detection path 30 and the optical waveguide 20 can be simultaneously formed on the semiconductor substrate 1 by the same process. For example, the optical waveguide 20 and the core layer 201 of the detection path 30 can be formed in the same layer.

  Below, the manufacturing method of the semiconductor substrate 1 by which the optical amplifier 10, the optical waveguide 20, and the detection path 30 are arrange | positioned is demonstrated. The manufacturing method described below is an example, and it is needless to say that the manufacturing method including this modification can be realized by various other manufacturing methods.

  First, an example of a manufacturing method of the optical amplifier 10 shown in FIG. 2 will be described with reference to FIGS. 3A to 21B, FIG. 3A is a process cross-sectional view along the II-II direction in FIG. 1, and FIG. 2B is a process cross-sectional view along the II direction in FIG. .

(A) A semiconductor substrate 1 to be the lower cladding layer 102 is prepared. Then, the active layer 103 and the upper cladding layer 104 are sequentially stacked on the semiconductor substrate 1. Thereafter, an insulating film 501 such as a silicon oxide (SiO ₂ ) film is formed. Then, as shown in FIG. 3, the insulating film 501 other than the region where the optical amplifier 10 is formed is removed.

  (B) Using the insulating film 501 as a mask, a part of the upper portion of the upper clad layer 104 is removed by etching. Specifically, as shown in FIG. 4, after the upper portion of the upper cladding layer 104 is etched by about 1500 nm by dry etching, the upper portion of the upper cladding layer 104 is further etched by about 500 nm by wet etching. As a result, as shown in FIG. 5, a ridge-shaped stripe portion 104A is formed on the upper cladding layer 104 along the direction in which the first laser beam L1 and the second laser beam L2 propagate.

(C) After the insulating film 501 is removed, an insulating film 110 made of a SiO ₂ film or the like is newly formed on the entire surface of the upper cladding layer 104 as shown in FIG. Next, as illustrated in FIG. 7, a resist film 502 is applied over the insulating film 110.

  (D) As shown in FIG. 8, the resist film 502 is etched until the upper surface of the convex portion of the insulating film 110 is exposed. Thereafter, as shown in FIG. 9, the upper portion of the convex portion of the insulating film 110 is etched using the resist film 502 as a mask to expose the upper surface of the stripe portion 104 </ b> A of the upper cladding layer 104. A side surface of the stripe portion 104 </ b> A of the upper cladding layer 104 is covered with an insulating film 110.

  (E) After removing the resist film 502, a new resist film 503 is applied over the entire surface, and using a photolithography technique, as shown in FIG. 10, the resist other than the region where the upper electrode 105 of the optical amplifier 10 is to be formed The film 503 is removed. Thereafter, as shown in FIG. 11, a metal film 105A to be the upper electrode 105 is deposited on the resist film 503 and the region from which the resist film 503 has been removed. For example, a titanium (Ti) / gold (Au) film or the like can be used as the metal film 105A.

  (F) As shown in FIG. 12, the resist film 503 is removed, and the upper electrode 105 is formed by a lift-off method. Thereafter, as shown in FIG. 13, the lower electrode 101 is formed on the back surface of the semiconductor substrate 1. For the lower electrode 101, for example, an Au / germanium (Ge) film or the like can be employed.

  (G) A resist film 504 is applied to the entire surface, and then patterned using a photolithography technique to leave only the resist film 504 on the region where the optical amplifier 10 is to be formed, as shown in FIG. Using the resist film 504 as a mask, the insulating film 110 is etched away as shown in FIG.

  (H) After removing the resist film 504 as shown in FIG. 16, the upper cladding layer 104, the active layer 103, and a part of the upper portion of the semiconductor substrate 1 are etched using the insulating film 110 and the upper electrode 105 as a mask. . As shown in FIG. 17, the unetched region of the semiconductor substrate 1 becomes the lower cladding layer 102.

(I) As shown in FIG. 18, a dielectric film 120A to be the AR film 120 is formed on the entire surface. As the dielectric film 120A, for example, a laminated body of tantalum oxide (Ta ₂ O ₅ ) and SiO ₂ can be employed.

  (N) Next, after a resist film 505 is applied to the entire surface of the dielectric film 120A, as shown in FIG. 19, the resist film 505 on the upper surface of the optical amplifier 10 is removed by using a photolithography technique. Using the resist film 505 as a mask, the dielectric film 120A on the upper surface of the optical amplifier 10 is removed by etching as shown in FIG. Thereafter, the resist film 505 is removed, and the optical amplifier 10 is completed as shown in FIG.

  Next, an example of a method for forming the optical waveguide 20 after forming the optical amplifier 10 will be described with reference to FIGS. In each of FIGS. 22 to 31, (a) is a process cross-sectional view along the II direction in FIG. 1, and (b) is a process top view.

  (L) As shown in FIG. 22, a polymer film 202A, which is the lower region of the cladding layer 202, is formed on the entire surface of the semiconductor substrate 1 on which the optical amplifier 10 shown in FIG. To do. As shown in FIG. 22, the film thickness of the polymer film 202A is set so that the position of the upper surface of the polymer film 202A is below the active layer 103.

  (E) After applying the resist film 506 to the entire surface of the polymer film 202A, as shown in FIG. 23, the resist film 506 above the optical amplifier 10 and the peripheral area of the optical amplifier 10 is removed by using a photolithography technique. Using this resist film 506 as a mask, the polymer film 202A in contact with the upper surface and output surface of the optical amplifier 10 is removed by etching to form the lower region of the optical waveguide 20 and the cladding layer 202 of the detection path 30. At this time, as shown in FIG. 24, the polymer film 202A is etched so that a part of the lower region of the cladding layer 202 in contact with the output surface of the optical amplifier 10 remains.

  (C) After removing the resist film 506, as shown in FIG. 25, a polymer film 201A to be the core layer 201 is formed with a film thickness of, for example, about 1 μm on the lower region of the cladding layer 202 and the upper surface of the optical amplifier 10. To do. A material having a higher refractive index than that of the polymer film 202A is selected for the polymer film 201A.

  (F) After the resist film 507 is applied to the entire surface of the polymer film 201A, the resist film 507 on the polymer film 201A in a region other than the region where the core layer 201 is formed is removed using a photolithography technique. The width of the core layer 201 is set to about 3 μm, for example. At this time, as shown in FIG. 26, patterning is performed so as to leave the resist film 507 on the outer edge portion of the AR film 120 and the upper electrode 105. Then, the polymer film 201A is removed by etching using the resist film 507 as a mask to form the optical waveguide 20 and the core layer 201 of the detection path 30 as shown in FIG. For this reason, the core layer 201 is formed on the outer edge of the optical amplifier 10. Thereafter, the resist film 507 is removed.

  (E) As shown in FIG. 28, a polymer film 202B made of the same material as the polymer film 202A that becomes the upper region of the cladding layer 202 over the entire surface of the lower layer of the core layer 201 and the cladding layer 202 and the exposed upper electrode 105. Is formed with a film thickness of about 5 to 7 μm. After the resist film 508 is applied to the entire surface of the polymer film 202B, as shown in FIG. 29, the resist film 508 on the upper surface of the optical amplifier 10 is removed using a photolithography technique. At this time, as shown in FIG. 29, the resist film 508 is patterned so that the resist film 508 remains above the outer edge portion of the upper electrode 105 and the resist film 508 covers the end portion 105 a of the upper electrode 105. The resist film 508 is patterned so that the position of the end face of the core layer 201 matches the position of the end face 508A of the resist film 508.

  (T) As shown in FIG. 30, the polymer film 202B is removed by etching using the resist film 508 as a mask to form an upper region of the optical waveguide 20 and the cladding layer 202 of the detection path 30. Thereafter, as shown in FIG. 31, the resist film 508 is removed, and the semiconductor substrate 1 shown in FIG. 1 is completed.

  For example, the signal detector 40 is disposed as follows on the semiconductor substrate 1. As shown in FIG. 32A, first, the cavity 401 is formed by etching away the cladding layer 202 and the core layer 201 at the end of the detection path 30 where the signal detector 40 is arranged. FIG. 32B is a cross-sectional view taken along the III-III direction of FIG. At this time, a part of the upper portion of the semiconductor substrate 1 may be removed by etching. Etching until reaching the semiconductor substrate 1 is more preferable in terms of heat dissipation of the signal detector 40. In addition, the end face of the optical waveguide of the core layer 201, that is, the end face exposed in the cavity 401, is preferably inclined by several degrees with respect to the central axis of the optical waveguide. Further, in order to reduce reflection at the end face, an AR coating may be applied to the end face.

  Thereafter, the signal detector 40 is mounted in a cavity 401 formed by etching away the cladding layer 202 and the core layer 201. When a photodiode is employed for the signal detector 40, the photodiode is mounted on the semiconductor substrate 1 so that the light receiving region of the photodiode is optically coupled to the core layer 201 of the detection path 30. If necessary, as shown in FIGS. 33 (a) and 33 (b), an extraction electrode 405 for applying a voltage to the signal detector 40 is formed in the cavity 401 formed in the semiconductor substrate 1. The signal detector 40 is mounted on the semiconductor substrate 1. FIG. 33B is a cross-sectional view taken along the III-III direction of FIG. The extraction electrode 405 is formed by a lift-off method or the like. For the extraction electrode 405, for example, a stacked body in which a Ti layer / Pt layer / Au layer is stacked in order from the semiconductor substrate 1 side can be employed.

  For patterning in each of the above processes, a photolithography technique generally used in a semiconductor process, an etching method using a resist film as a mask, or the like can be applied.

In the above manufacturing method, a part of the upper portion of the upper cladding layer 104 is removed by etching, and the stripe portion 104A is formed along the direction in which the first laser light L1 and the second laser light L2 propagate. Since the stripe portion 104A is formed into a ridge shape (mesa type) and the insulating film 110 covers the portion other than the upper surface of the stripe portion 104A in contact with the upper electrode 105, it is possible to gently confine light from the lateral direction. It becomes easy to control the operation. The insulating film 110 is preferably made of a material having a refractive index larger than 1, such as zirconia (ZrO ₂ ) or SiO ₂ . By adopting the above structure, the current injection efficiency can be improved by narrowing the current path between the lower electrode 101 and the upper electrode 105. Further, leakage current from the side surface can be prevented.

  In the manufacturing method in which the optical amplifier 10 is mounted on the semiconductor substrate 1 after the optical waveguide 20 is formed on the semiconductor substrate 1, it is difficult to bring the end face of the optical waveguide 20 into close contact with the output surfaces 11 and 12 of the optical amplifier 10. There is a high possibility that space is included in the light path. Furthermore, when the optical amplifier 10 is fixed to the semiconductor substrate 1 with solder or the like after the optical waveguide 20 and the optical amplifier 10 are aligned, the position of the optical amplifier 10 may change. For this reason, there arises a problem that the center of the mode field of the optical amplifier 10 does not coincide with the center of the core layer 201 of the optical waveguide 20. As a result, the coupling efficiency between the optical amplifier 10 and the optical waveguide 20 decreases.

  However, in the optical gyro sensor according to the first embodiment of the present invention, after the optical amplifier 10 is disposed on the semiconductor substrate 1, the end surface of the core layer 201 is the output surface of the optical amplifier 10 using photolithography technology. An optical waveguide 20 is formed on the semiconductor substrate 1 so as to be in contact with the semiconductor substrate 1. Therefore, the output surfaces 11 and 12 of the optical amplifier 10 and the end surface perpendicular to the circumferential direction of the core layer 201 can be easily and reliably brought into contact with each other. Furthermore, since alignment is performed using a photolithography technique, the center of the mode field of the optical amplifier 10 and the center of the core layer 201 of the optical waveguide 20 can be matched with high accuracy. As a result, the coupling efficiency between the optical amplifier 10 and the optical waveguide 20 is improved.

  Further, as described above, the heat treatment temperature of the optical amplifier 10 is reduced by setting the heat treatment temperature in the manufacturing process of the optical waveguide 20 to a certain value or less by, for example, configuring the optical waveguide 20 with a polymer having a firing temperature of about 350 ° C. Damage can be suppressed. In consideration of the heat resistance of the material used for the optical waveguide 20, the heat treatment temperature in the manufacturing process of the optical gyro sensor after the optical waveguide 20 is formed should be set lower than the heat resistance temperature of the optical waveguide 20.

  As described above, according to the optical gyro sensor and the manufacturing method thereof according to the first embodiment of the present invention, the optical gyro capable of integrating the optical waveguide 20 and the optical amplifier 10 on the semiconductor substrate 1 with high accuracy. A sensor and a manufacturing method thereof can be provided. This integration reduces the size of the optical gyro sensor, reduces expensive optical components, and can be manufactured at a low cost, thereby expanding the application to consumer devices such as digital video cameras and car navigation systems. .

(Second Embodiment)
As shown in FIG. 34, the optical gyro sensor according to the second embodiment of the present invention includes a lower electrode 101, a lower cladding layer 102, an active layer 103, an upper cladding layer 104, and an upper electrode 105, which are stacked. 1 is different from the optical gyro sensor shown in FIG. 1 in that the optical amplifier 10 in which the AR film 120 is arranged on the output surface is connected to the semiconductor substrate 1 by solder 601. Other configurations are the same as those of the first embodiment shown in FIG. FIG. 34 is a cross-sectional view taken along the direction II of FIG. As shown in FIG. 34, an extraction electrode 602 to the outside of the semiconductor substrate 1 is formed on the semiconductor substrate 1, and the optical amplifier 10 is connected to the extraction electrode 602 by solder 601. The material of the semiconductor substrate 1 can be selected without depending on the material of the optical amplifier 10, and for example, a silicon substrate, a sapphire substrate, a GaAs substrate, a gallium nitride (GaN) substrate, or the like can be adopted.

  As shown in FIG. 34, the optical waveguide 20 is formed in contact with the output surface 11 of the optical amplifier 10. Although not shown, the optical waveguide 20 is formed in contact with the other output surface 12 of the optical amplifier 10 facing the output surface 11.

  Below, with reference to FIGS. 35-45, the manufacturing method of the semiconductor substrate 1 which concerns on the 2nd Embodiment of this invention is demonstrated. In addition, the manufacturing method described below is an example, and it is needless to say that it can be realized by various other manufacturing methods including this modified example. 35 to 45 are process cross-sectional views along the II-II direction of FIG.

  (A) An optical amplifier 10 and a semiconductor substrate 1 on which the optical amplifier 10 is arranged are prepared. As shown in FIG. 35, the optical amplifier 10 has a structure in which a lower electrode 101, a lower cladding layer 102, an active layer 103, an upper cladding layer 104, and an upper electrode 105 are stacked, and an AR film 120 is disposed on the output surface of the laser beam. It is. In addition, a region of the semiconductor substrate 1 where the optical amplifier 10 is disposed is etched into a concave shape, and an extraction electrode 602 is disposed in the concave portion.

  (B) As shown in FIG. 36, the lower electrode 101 of the optical amplifier 10 and the extraction electrode 602 are connected by solder 601, and the optical amplifier 10 is disposed on the semiconductor substrate 1.

(C) A polymer film 202A to be a lower region of the cladding layer 202 is formed with a film thickness of about 5 to 7 μm on the entire surface of the semiconductor substrate 1 on which the optical amplifier 10 is disposed. As shown in FIG. 37 , the gap between the stepped portion of the semiconductor substrate 1 and the optical amplifier 10 is filled with a polymer film 202A. The film thickness of the polymer film 202A is set so that the position of the upper surface of the polymer film 202A is below the active layer 103.

  (D) After applying the resist film 701 to the entire surface of the polymer film 202A, as shown in FIG. 38, the optical amplifier 10 and the resist film 701 above the periphery of the optical amplifier 10 are removed by using a photolithography technique. Using the resist film 701 as a mask, the polymer film 202A on the upper surface and side surfaces of the optical amplifier 10 is removed by etching to form the lower region of the optical waveguide 20 and the cladding layer 202 of the detection path 30. At this time, as shown in FIG. 39, the polymer film 202A is etched so that a part of the lower region of the cladding layer 202 in contact with the output surface of the optical amplifier 10 remains.

  (E) After removing the resist film 701, as shown in FIG. 40, a polymer film 201A to be the core layer 201 is formed in the lower region of the cladding layer 202 and the upper surface of the optical amplifier 10.

  (F) After the resist film 702 is applied to the entire surface of the polymer film 201A, the resist film 702 on the polymer film 201A in a region other than the region where the core layer 201 is formed is removed using a photolithography technique. At this time, as shown in FIG. 41, patterning is performed so as to leave a resist film 702 on the outer edge of the optical amplifier 10. Then, the polymer film 201A is removed by etching using the resist film 702 as a mask to form the optical waveguide 20 and the core layer 201 of the detection path 30 as shown in FIG. For this reason, the core layer 201 is formed on the outer edge of the optical amplifier 10.

  (G) As shown in FIG. 43, a polymer film 202 </ b> B that becomes the upper region of the cladding layer 202 is formed on the lower region of the core layer 201, the cladding layer 202, and the entire surface of the optical amplifier 10. After applying the resist film 703 over the entire surface of the polymer film 202B, as shown in FIG. 44, the resist film 703 on the upper surface of the optical amplifier 10 is removed using a photolithography technique. At this time, as shown in FIG. 44, the resist film 703 at the outer edge of the optical amplifier 10 is left, and the resist film 703 is patterned so that the position of the end face of the core layer 201 and the position of the end face of the resist film 703 coincide.

  (H) As shown in FIG. 45, the polymer film 202B is etched away using the resist film 703 as a mask to form the upper region of the optical waveguide 20 and the cladding layer 202 of the detection path 30. Thereafter, the resist film 703 is removed to complete the semiconductor substrate 1 shown in FIG.

  As described above, in the optical gyro sensor shown in FIG. 34, the completed SOA is mounted on the semiconductor substrate 1. For this reason, compared with the optical gyro sensor shown in FIG. 1, the yield fall in the part which forms the optical amplifier 10 is suppressed. Further, since the optical amplifier 10 on which the AR film 120 is coated in advance is used, the reflectance of the AR film 120 can be reduced as compared with the method of forming the AR film 120 on the semiconductor substrate 1. Furthermore, the degree of freedom of the material and size of the semiconductor substrate 1 is increased as compared with the case where the optical amplifier 10 and the optical waveguide 20 are formed on the same semiconductor substrate 1.

  As described above, in the optical gyro sensor shown in FIG. 34, after the optical amplifier 10 is arranged on the semiconductor substrate 1, the end surface of the core layer 201 is made of the optical amplifier 10 by using a semiconductor manufacturing method such as a photolithography technique. An optical waveguide 20 is formed on the semiconductor substrate 1 so as to be in contact with the output surfaces 11 and 12. Therefore, the output surfaces 11 and 12 of the optical amplifier 10 and the end surface of the core layer 201 can be easily brought into contact, and the center of the mode field of the optical amplifier 10 and the center of the core layer 201 of the optical waveguide 20 are It can be matched with high accuracy. As a result, according to the optical gyro sensor and the manufacturing method thereof according to the second embodiment of the present invention, the optical gyro sensor capable of integrating the optical waveguide 20 and the optical amplifier 10 on the semiconductor substrate 1 with high accuracy and the manufacturing thereof. Can provide a method. Others are substantially the same as those in the first embodiment, and redundant description is omitted.

(Other embodiments)
As described above, the present invention has been described according to the first and second embodiments. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the description of the first and second embodiments already described, the light extraction unit 301 provided in the detection path 30 is provided at one location. However, the light extraction unit 301 is provided at two locations, and the first laser beam L1 and the first light extraction unit 301 are provided. The two laser beams L2 may be extracted by different light extraction units 301.

  As described above, the present invention naturally includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

It is a schematic diagram which shows the structure of the optical gyro sensor which concerns on the 1st Embodiment of this invention. It is sectional drawing along the II direction of FIG. It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 1). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 2). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 3). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 4). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 5). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 6). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 7). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 8). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 9). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 10). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 11). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 12). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 13). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 14). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 15). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 16). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 17). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 18). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 19). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 20). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 21). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 22). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 23). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 24). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 25). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 26). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 27). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 28). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 1st Embodiment of this invention (the 29). It is process drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the modification of the 1st Embodiment of this invention (the 1). It is process drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the modification of the 1st Embodiment of this invention (the 2). It is a schematic diagram which shows the structure of the optical gyro sensor which concerns on the 2nd Embodiment of this invention. It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 2nd Embodiment of this invention (the 1). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 2nd Embodiment of this invention (the 2). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 2nd Embodiment of this invention (the 3). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 2nd Embodiment of this invention (the 4). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 2nd Embodiment of this invention (the 5). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 2nd Embodiment of this invention (the 6). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 2nd Embodiment of this invention (the 7). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 2nd Embodiment of this invention (the 8). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 2nd Embodiment of this invention (the 9). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 2nd Embodiment of this invention (the 10). It is process sectional drawing for demonstrating the manufacturing method of the optical gyro sensor which concerns on the 2nd Embodiment of this invention (the 11).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate 10 ... Optical amplifier 11, 12 ... Output surface 20 ... Optical waveguide 30 ... Detection path 40 ... Signal detector 50 ... Angular velocity calculation circuit 101 ... Lower electrode 102 ... Lower clad layer 103 ... Active layer 104 ... Upper clad layer DESCRIPTION OF SYMBOLS 105 ... Upper electrode 110 ... Insulating film 120 ... AR film 201 ... Core layer 202 ... Cladding layer 301 ... Light extraction part 302 ... Detection part A ... Light extraction area B ... Signal detection area L1 ... First laser beam L1a ... First detection Laser light L2 ... second laser light L2a ... second detection laser light

Claims (8)

A semiconductor substrate;
An optical amplifier disposed on the semiconductor substrate and having first and second output surfaces;
The first and second output surfaces are arranged on the semiconductor substrate so as to form a ring-shaped optical path together with the optical amplifier having end faces in close contact with the first and second output surfaces, and are output from the first output surface. An optical waveguide in which one laser beam and a second laser beam output from the second output surface propagate in different circumferential directions;
A detection path disposed on the semiconductor substrate, in which a part of each of the first and second laser beams is transferred from the optical waveguide;
An optical gyro sensor comprising: a signal detector that detects a beat signal generated by combining a part of each of the first and second laser beams transferred to the detection path.   2. The optical gyro sensor according to claim 1, wherein the optical amplifier is a semiconductor optical amplifier.   The optical gyro sensor according to claim 1, wherein the optical waveguide is made of a polymer.   4. The light according to claim 1, wherein the optical waveguide has a laminated structure including a core layer laminated on the semiconductor substrate and a cladding layer surrounding the core layer. 5. Gyro sensor. Disposing an optical amplifier having first and second output surfaces on a semiconductor substrate;
The first and second output surfaces are arranged on the semiconductor substrate so as to form a ring-shaped optical path together with the optical amplifier having end faces in close contact with the first and second output surfaces, and are output from the first output surface. Forming an optical waveguide in which one laser beam and a second laser beam output from the second output surface propagate in different circumferential directions;
The semiconductor substrate has a detection path through which a part of each of the first and second laser beams propagates, and a distance from the optical waveguide is a distance at which a part of each of the first and second laser beams moves from the optical waveguide. And a step of forming the optical gyro sensor.   6. The method of manufacturing an optical gyro sensor according to claim 5, wherein the optical amplifier is arranged by laminating a semiconductor layer on the semiconductor substrate.   7. The method of manufacturing an optical gyro sensor according to claim 5, wherein the optical waveguide is made of a polymer.   6. The method of claim 5, further comprising disposing a signal detector on the semiconductor substrate for detecting a beat signal generated in the detection path by combining a part of each of the first and second laser beams. 8. A method for manufacturing an optical gyro sensor according to claim 1.

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