JP2006030033A - Direction detection element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a direction detecting element that can be reduced in size and thickness and can accurately detect the direction of incident light.
SOLUTION: Four rectangular contact pads 201-204 are arranged on four PIN photodiodes on a substrate. Between contact pads 201-204, wall portions 301-304 extending radially at an angle of 90 degrees with respect to reference point P are provided, and light absorber 8 is provided on wall portions 301-304. The concave portion 10 is formed along one side of the walls 301 to 304, and the groove 11 is formed along the other side and the side surrounding the end. Rectangular light receiving regions 101 to 104 of PIN photodiodes are formed so as to be adjacent to the walls 301 to 304. The wall portions 301 to 304 stand up vertically as the wall portions 301 to 304 are curved. The light applied to the walls 301 to 304 is absorbed by the light absorber 8 and is not reflected.
[Selection] Figure 1

Description

  The present invention relates to a direction detection element that outputs an electrical signal that gives information on the incident direction of light.

  Conventionally, a direction detector that detects the incident direction of light has been developed (see Patent Documents 1 and 2). In a conventional direction detector, a circular opening is provided on the top surface of the housing, and a circular detector is disposed on the bottom surface of the housing. The circular detector includes a plurality of pixels arranged in an annular shape. Light enters the detector through a circular opening in the housing. In such a direction detector, the light receiving positions of a plurality of pixels arranged in a ring shape differ depending on the direction of incident light. Therefore, the direction of incident light can be detected based on the outputs of a plurality of pixels of the detector.

  Research has also been conducted on direction detection elements that can be miniaturized and thinned by using micro origami technology (see Patent Document 3).

In the direction detection element described in Patent Document 3, four PIN photodiodes are arranged radially on a substrate. Four walls are provided that stand vertically along the four PIN photodiodes. Thereby, a part of the light irradiated to the direction detection element is shielded by the four wall portions, and the light not shielded by the PIN photodiode adjacent to the wall portion is received. The direction of light can be detected from the current values of these four PIN photodiodes.
US Pat. No. 5,319,188 US Pat. No. 5,587,580 Japanese Patent Laid-Open No. 2003-133583

  However, in the direction detection element described in Patent Document 3, an error may occur in the light direction detection.

  FIG. 14, FIG. 15 and FIG. 16 are schematic cross-sectional views showing the positional relationship between the vertically standing wall portion and the light receiving region of the photodiode in the direction detecting element. 14 and 15 show light L1 and L2 irradiated from different directions, respectively, and FIG. 16 shows light L3 irradiated from a certain direction and light L4 reflected by the wall 301.

  As shown in FIGS. 14 and 15, a part of the light L <b> 1 and L <b> 2 irradiated from different directions is incident on the light receiving region 101. In this case, since the amount of light incident on the light receiving region 101 differs depending on the light irradiation direction, the light receiving region 101 generates a different current. Thereby, the direction of light can be accurately detected.

  However, as shown in FIG. 16, when the light L4 reflected by the wall portion 301 of the light L3 enters the light receiving region 101, the amount of light incident on the light receiving region 101 is increased by the light L4. Thereby, an error occurs in the light direction detection.

  An object of the present invention is to provide a direction detection element that can be reduced in size and thickness and can accurately detect the direction of incident light.

  In the direction detecting element according to the first invention, a first layer, a second layer, and a third layer are sequentially formed on a substrate, and the second layer is a first semiconductor layer having a first lattice constant. And a second semiconductor layer having a second lattice constant smaller than the first lattice constant, a light shielding portion forming region is disposed in the third layer, and along one side of the light shielding forming region The light receiving region of the light receiving element is formed in the third layer, and the third layer, the second layer, and the first layer are excluded except for a part of the region surrounding the periphery of the light shielding portion forming region of the third layer. As the layer is removed, the plurality of light shielding portion formation regions and the first layer in the partial region are removed, the third layer in the partial region is removed, and the second layer in the light shielding portion formation region is partially By curving in the area, a light-shielding part standing along the light-receiving area of the light-receiving element is formed, and reflection by the light-shielding part Reducing means for reducing the light incident on the light receiving area of the light receiving elements of those that are provided.

  In the direction detection element according to the present invention, the third layer, the second layer, and the first layer are removed except for a part of the region surrounding the light shielding portion forming region, and the light shielding portion forming region and the one are separated. Since the first layer in the partial region is removed, the second layer in the light shielding portion forming region is in a released state while being connected to the surrounding region only in a partial region. Since the lattice constant of the first semiconductor layer of the second layer is larger than the lattice constant of the second semiconductor layer, distortion due to the difference of the lattice constant occurs in the second layer. Thereby, the second layer is curved so as to relieve strain. Along with this, the light shielding part forming region of the third layer on the second layer stands at a predetermined angle with respect to the substrate. As a result, a light-shielding portion that rises along the light-receiving region of the light-receiving element is formed. Further, there is provided a reducing means for reducing light incident on the light receiving region of the light receiving element among the reflected light from the light shielding portion.

  As described above, the second layer is automatically bent so as to relieve the strain caused by the difference in lattice constant between the first semiconductor layer and the second semiconductor layer, and thus rises along the light receiving region of the light receiving element. The light shielding part can be easily formed. In this case, the angle of the light shielding portion can be easily and accurately controlled by adjusting the composition and thickness of the first semiconductor layer and the second semiconductor layer.

  When light enters the direction detection element, the shadow of the light shielding portion is projected onto the light receiving area of the light receiving element. In this case, the amount of light received in the light receiving region varies depending on the elevation angle of incident light with respect to the surface of the light receiving region of the light receiving element. Further, the light incident on the light receiving element among the light reflected by the light shielding portion is reduced by the reducing means. Accordingly, it is possible to accurately detect the direction of the incident light in the vertical plane with respect to the surface of the light receiving region of the light receiving element based on the current flowing through the light receiving element.

  Since the direction detection element according to the present invention includes a plurality of semiconductor layers and a standing structure of the semiconductor layers, the direction detection element can be reduced in size and thickness. In addition, since the current flowing through the light receiving element is relatively large, the intensity of incident light necessary for detection is reduced, and the direction detecting element can be further reduced in size and thickness.

  In the direction detection element according to the second invention, a first layer, a second layer, and a third layer are sequentially formed on a substrate, and the second layer is a first semiconductor layer having a first lattice constant. And a second semiconductor layer having a second lattice constant smaller than the first lattice constant, and a plurality of light-shielding part forming regions are formed at equiangular intervals around a predetermined reference point in the third layer. The light receiving regions of the plurality of light receiving elements are formed on the third layer along one side of each of the plurality of light shielding formation regions, and the regions surrounding the plurality of light shielding portion formation regions of the third layer are respectively The third layer, the second layer, and the first layer are removed except for each partial region, and the plurality of light shielding portion forming regions and the first layer in each partial region are removed, The third layer of each partial region is removed, and a plurality of light shielding portion formation regions The second layer is curved in each partial region, so that a plurality of light shielding portions standing along the light receiving regions of the plurality of light receiving elements are formed, and the plurality of light receiving elements out of the reflected light from the plurality of light shielding portions are formed. A reduction means for reducing light incident on the light receiving region is provided.

  In the direction detection element according to the present invention, the third layer, the second layer, and the first layer are removed except for a part of each of the regions surrounding the plurality of light shielding portion formation regions, and Since the light shielding portion forming regions and the first layers of the respective partial regions are removed, the second layers in the plurality of light shielding portion forming regions are released while being connected to the surrounding regions only in the respective partial regions. It becomes a state. Since the lattice constant of the first semiconductor layer of the second layer is larger than the lattice constant of the second semiconductor layer, distortion due to the difference of the lattice constant occurs in the second layer. Thereby, the second layer is curved so as to relieve strain. Accordingly, the plurality of light shielding portion forming regions of the third layer on the second layer stand up at a predetermined angle with respect to the substrate. As a result, a plurality of light shielding portions that stand along the light receiving regions of the plurality of light receiving elements are formed. Further, there is provided a reducing means for reducing light incident on the light receiving regions of the plurality of light receiving elements among the reflected light from the plurality of light shielding portions.

  As described above, the second layer is automatically curved so as to relieve the strain caused by the difference in lattice constant between the first semiconductor layer and the second semiconductor layer, and thereby along the light receiving regions of the plurality of light receiving elements. A plurality of standing light shielding parts can be easily formed. In this case, the angles of the plurality of light shielding portions can be easily and accurately controlled by adjusting the composition and thickness of the first semiconductor layer and the second semiconductor layer.

  When light enters the direction detection element, the shadow of each light shielding portion is projected onto the light receiving area of each light receiving element. In this case, since the plurality of light shielding portions are arranged at equal angular intervals with the reference point as the center, the amount of light received in each light receiving region varies depending on the elevation angle and azimuth angle of the incident light. Further, the light incident on the light receiving regions of the plurality of light receiving elements among the light reflected by the plurality of light shielding portions is reduced by the reducing means. Therefore, it is possible to accurately detect the direction of incident light based on the currents flowing through the plurality of light receiving elements.

  Since the direction detection element according to the present invention includes a plurality of semiconductor layers and a standing structure of the semiconductor layers, the direction detection element can be reduced in size and thickness. In addition, since the current flowing through each light receiving element is relatively large, the intensity of incident light required for detection is reduced, and the direction detecting element can be further reduced in size and thickness.

  In the direction detection element, the third layer of each partial region may be removed. Thereby, the second layer can be easily curved in a partial region.

  The plurality of light shielding portions include a flat portion standing with respect to the light receiving regions of the plurality of light receiving elements, and a support portion curved with respect to the flat portion so as to support the flat portion at a predetermined angle with respect to the third layer. You may have.

  Thereby, the flat part of the light-shielding part can stand up at an exactly constant angle with respect to the third layer.

  The reducing means may include an absorber that is provided on the surface of the light shielding portion and absorbs light. In this case, light is absorbed by the absorber provided on the surface of the light shielding portion. Thereby, the light reflected by the light shielding portion does not enter the light receiving region of the light receiving element. Therefore, it is possible to accurately detect the direction of light based on the current flowing through the light receiving element.

  The reducing means may include a concavo-convex surface that is formed on the surface of the light shielding portion and diffuses and reflects light. In this case, light is irregularly reflected by the uneven surface formed on the surface of the light shielding portion. This makes it difficult for the irregularly reflected light to enter the light receiving region of the light receiving element. Therefore, it is possible to accurately detect the direction of light based on the current flowing through the light receiving element.

  The reducing means may include a reflecting member that is provided on the surface of the light shielding portion and reflects light in a direction different from the light receiving region of the light receiving element. In this case, the light is reflected in a direction different from the light receiving region of the light receiving element by the reflecting member provided on the surface of the light shielding portion. Thereby, it is possible to prevent the light reflected by the light shielding portion from entering the light receiving region of the light receiving element. Therefore, it is possible to accurately detect the direction of light based on the current flowing through the light receiving element.

  One method of manufacturing a direction detecting element includes a step of forming a first layer on a substrate, a first semiconductor layer having a first lattice constant on the first layer, and smaller than the first lattice constant. Forming a second layer including a stacked structure with a second semiconductor layer having a second lattice constant, and forming a third layer including a light receiving element on the second layer; A light-shielding part forming region is arranged in the third layer, and a light-receiving region of the light-receiving element is formed in the third layer along one side of the light-shielding forming region, and surrounds the light-shielding part forming region of the third layer. Removing the third layer, the second layer, and the first layer except for a part of the region, and selectively removing the light shielding part forming region and the first layer in the part region The second layer of the light shielding part forming region is curved in a partial region, thereby receiving the light receiving element. A step of forming a light-shielding portion that rises along the region, and a step of forming, in the light-shielding portion formation region, reduction means for reducing light incident on the light-receiving region of the light-receiving element among the light reflected by the light-shielding portion. Is.

  In this method of manufacturing the direction detecting element, the third layer, the second layer, and the first layer are removed except for a part of the region surrounding the light shielding portion forming region, and the light shielding portion forming region and the one layer are formed. Since the first layer in the partial region is removed, the second layer in the light shielding portion forming region is in a released state while being connected to the surrounding region only in a partial region. Since the lattice constant of the first semiconductor layer of the second layer is larger than the lattice constant of the second semiconductor layer, distortion due to the difference of the lattice constant occurs in the second layer. Thereby, the second layer is curved so as to relieve strain. Along with this, the light shielding part forming region of the third layer on the second layer stands at a predetermined angle with respect to the substrate. As a result, a light shielding portion is formed that stands along the light receiving region of the light receiving element. Further, there is provided a reducing means for reducing light incident on the light receiving region of the light receiving element among the reflected light from the light shielding portion.

  As described above, the second layer is automatically bent so as to relieve the strain caused by the difference in lattice constant between the first semiconductor layer and the second semiconductor layer, and thus rises along the light receiving region of the light receiving element. The light shielding part can be easily formed. In this case, the angle of the light shielding portion can be easily and accurately controlled by adjusting the composition and thickness of the first semiconductor layer and the second semiconductor layer.

  When light enters the direction detection element, the shadow of the light shielding portion is projected onto the light receiving area of the light receiving element. In this case, the amount of light received in the light receiving region varies depending on the elevation angle of incident light with respect to the surface of the light receiving region of the light receiving element. Further, the light incident on the light receiving region of the light receiving element among the light reflected by the light shielding portion is reduced by the reducing means. Accordingly, it is possible to accurately detect the direction of the incident light in the vertical plane with respect to the surface of the light receiving region of the light receiving element based on the current flowing through the light receiving element.

  Since the direction detecting element manufactured by this method includes a plurality of semiconductor layers and a standing structure of the semiconductor layers, the direction detecting element can be reduced in size and thickness. In addition, since the current flowing through the light receiving element is relatively large, the intensity of incident light necessary for detection is reduced, and the direction detecting element can be further reduced in size and thickness.

  Another method of manufacturing the direction detection element includes a step of forming a first layer on a substrate, a first semiconductor layer having a first lattice constant on the first layer, and smaller than the first lattice constant. Forming a second layer including a stacked structure with a second semiconductor layer having a second lattice constant, and forming a third layer on the second layer. A plurality of light shielding portion forming regions are arranged at equal angular intervals around a predetermined reference point, and light receiving regions of the plurality of light receiving elements are respectively provided on the third layer along one side of each of the plurality of light shielding portion forming regions. Removing the third layer, the second layer, and the first layer except for a part of each of the regions formed and surrounding each of the plurality of light shielding portion forming regions of the third layer; A plurality of light shielding portion forming regions and a first layer in each partial region; By selectively removing, the second layer of the plurality of light shielding portion forming regions is curved in each partial region, thereby forming a plurality of light shielding portions standing along the light receiving regions of the plurality of light receiving elements, respectively. And a step of forming, in each of the plurality of light shielding portion forming regions, a reducing means for reducing light incident on the light receiving region of the light receiving element out of the light reflected by the light shielding portion.

  In the method of manufacturing the direction detection element, the third layer, the second layer, and the first layer are removed except for a part of each of the regions surrounding the plurality of light shielding portion formation regions, and Since the light shielding part forming region and the first layer of each partial region are removed, the second layer in the plurality of light shielding part forming regions is in a released state while being connected to the surrounding region only in each partial region. It becomes. Since the lattice constant of the first semiconductor layer of the second layer is larger than the lattice constant of the second semiconductor layer, distortion due to the difference of the lattice constant occurs in the second layer. Thereby, the second layer is curved so as to relieve strain. Accordingly, the plurality of light shielding portion forming regions of the third layer on the second layer stand up at a predetermined angle with respect to the substrate. As a result, a plurality of light shielding portions that stand along the light receiving regions of the plurality of light receiving elements are formed. Further, there is provided a reducing means for reducing light incident on the light receiving region of the light receiving element among the reflected light from the light shielding portion.

  As described above, the second layer is automatically curved so as to relieve the strain caused by the difference in lattice constant between the first semiconductor layer and the second semiconductor layer, and thereby along the light receiving regions of the plurality of light receiving elements. A plurality of standing light shielding parts can be easily formed. In this case, the angles of the plurality of light shielding portions can be easily and accurately controlled by adjusting the composition and thickness of the first semiconductor layer and the second semiconductor layer.

  When light enters the direction detection element, the shadow of each light shielding portion is projected onto the light receiving area of each light receiving element. In this case, since the plurality of light shielding portions are arranged at equal angular intervals with the reference point as the center, the amount of light received in each light receiving region varies depending on the elevation angle and azimuth angle of the incident light. Further, the light incident on the light receiving region of the light receiving element among the light reflected by the light shielding portion is reduced by the reducing means. Therefore, the direction of incident light can be detected based on the currents flowing through the plurality of light receiving elements.

  Since the direction detecting element manufactured by this method includes a plurality of semiconductor layers and a standing structure of the semiconductor layers, the direction detecting element can be reduced in size and thickness. In addition, since the current flowing through each light receiving element is relatively large, the intensity of incident light required for detection is reduced, and the direction detecting element can be further reduced in size and thickness.

  According to the present invention, the size and thickness can be reduced, and the direction of incident light can be accurately detected.

(First embodiment)
FIG. 1 is a schematic perspective view of a direction detection element according to the first embodiment of the present invention. FIG. 2 is a schematic plan view of the direction detection element of FIG. This direction detection element is a direction detection element that has a wall portion (light-shielding portion) standing substantially vertically on a substrate and detects an angle of incident light. FIG. 2 shows a state before the wall is raised in the manufacturing process of the direction detecting element of FIG.

  1 and 2, four rectangular contact pads 201 to 204 are arranged on four PIN photodiodes (not shown) formed on the substrate, respectively. Between these contact pads 201-204, four wall portions 301-304 extending radially at an angle of 90 degrees with respect to the reference point P are provided. Triangular auxiliary portions 301a to 304a are provided at the outer end portions of the wall portions 301 to 304, respectively, and triangular auxiliary portions 301b to 304b are provided at the center end portions, respectively. The recess 10 is formed along one side of the walls 301 to 304, and the groove 11 is formed along the other side and the side surrounding the end.

  Rectangular light-receiving areas 101 to 104 of PIN photodiodes are formed so as to be adjacent to one side of the walls 301 to 304 via the recess 10. The light receiving regions 101 to 104 have a finger structure composed of a plurality of stripes arranged in parallel and at equal intervals. Further, the light receiving regions 101 to 104 may have a structure including a plurality of slits arranged in parallel and at equal intervals.

  As the walls 301 to 304 are curved along the recess 10 in FIG. 2, the walls 301 to 304 stand vertically as shown in FIG. 1. In this case, the standing wall portions 301 to 304 have a flat surface. Further, the auxiliary portions 301a to 304a at the outer ends of the wall portions 301 to 304 and the auxiliary portions 301b to 304b at the end portions on the center side are bent substantially at right angles to the flat portions of the wall portions 301 to 304, respectively. ing. Thereby, each wall part 301-304 is fixed in the state standing upright. The light absorber 8 is formed on the surface of each of the walls 301 to 304. Details of the light absorber 8 will be described later.

  When light from a point light source or a parallel light source enters the direction detection element of the present embodiment, the shadows of the four wall portions 301 to 304 are projected onto the four light receiving regions 101 to 104. In this case, the amount of light incident on the four light receiving regions 101 to 104 varies depending on the direction of the incident light.

In the present embodiment, a current value I ₁₀₁ corresponding to the amount of light received in the light receiving region 101 is generated in the PIN photodiode, and a current value I ₁₀₂ corresponding to the amount of light received in the light receiving region 102 is generated in the PIN photodiode. A current value I ₁₀₃ corresponding to the amount of light received in the region 103 is generated in the PIN photodiode, and a current value I ₁₀₄ corresponding to the amount of light received in the light receiving region 104 is generated in the PIN photodiode. Details of the current values I _{101 to} I ₁₀₄ will be described later. As described above, the direction of incident light can be detected by comparing the amounts of received light (current values I _{101 to} I ₁₀₄ ) in the four light receiving regions 101 to ₁₀₄ .

  The width of each light receiving region 101 to 104 in the direction perpendicular to the side of each wall 301 to 304 is W, and the height of each wall 301 to 304 is H. The direction of incident light is expressed by the following azimuth angle (azimuth angle) θ and elevation angle φ. The azimuth angle θ is an angle measured clockwise from a direction parallel to the side of the wall 301 around the reference point P in the light receiving surfaces of the light receiving regions 101 to 104. The elevation angle φ is an angle measured from the light receiving surfaces of the light receiving regions 101 to 104 around the reference point P in a plane perpendicular to the light receiving surfaces of the light receiving regions 101 to 104.

  When detecting the direction of the incident light, a reverse bias is applied to the PIN photodiode under the light receiving areas 101 to 104 by an external circuit.

A typical response value for a PIN photodiode is 0.5 A / W. When the area of the light receiving region of the PIN photodiode is 1 mm ^2, a photocurrent of 50 μA can be obtained with an incident light intensity of 10 mW / cm ² .

For example, as shown in FIG. 2, when light is incident in the direction from the light receiving region 104 toward the light receiving region 102, the light receiving regions 103 and 104 are entirely irradiated with light, and the amount of received light reaches the maximum value. 101 and 102 are partially irradiated with light, and the amount of received light is smaller than the maximum value. Here, the current value when the maximum amount of received light and I _100. The current values of the light receiving areas 101 and ₁₀₂ are I ₁₀₁ and I ₁₀₂ , respectively. In this case, the azimuth angle θ of the incident light is expressed by the following equation.

θ = arctan [(I ₁₀₀ −I ₁₀₁ ) / (I ₁₀₀ −I ₁₀₂ )] (1)
The elevation angle φ is expressed by the following equation.

φ = arctan [(H / W) · {I ₁₀₀ / √ ((I ₁₀₀ −I ₁₀₂ ) ² + (I ₁₀₀ −I ₁₀₁ ) ² )}] (2)
Here, φ> arctan (H / W).

  Similarly, the azimuth angle θ and elevation angle φ of incident light can be calculated by calculation using current values corresponding to the amounts of light received by the four light receiving regions 101 to 104.

  A simulation for calculating the azimuth angle θ and the elevation angle φ of incident light from the current values corresponding to the amounts of light received in the light receiving regions 101 to 104 using the above equations (1) and (2) will be described later.

  3, FIG. 4, FIG. 5 and FIG. 6 are process diagrams showing a method of manufacturing the direction detecting element of FIG. FIG. 3A is a schematic plan view, and FIG. 3B is a schematic cross-sectional view showing the AA cross section of FIG. FIG. 4A is a schematic plan view, and FIG. 4B is a schematic cross-sectional view showing a BB cross section of FIG. FIG. 5A is a schematic plan view, and FIG. 5B is a schematic cross-sectional view taken along the line CC in FIG. 5A. FIG. 6A is a schematic plan view, and FIG. 6B is a schematic cross-sectional view showing the EE cross section of FIG. 6A.

First, as shown in FIG. 3, on a p-type GaAs substrate 1, a release layer (release layer) 2, a p-type InGaAs layer 3, a p-type GaAs layer 4, and a p-type made of p-type Al _x Ga _1-x As. An etching stop layer 7 made of Al _Y Ga _1-Y As, a p-type GaAs layer 61, a non-doped GaAs layer 62, and an n-type GaAs layer 63 are epitaxially grown in this order. A light absorber 8 made of carbon is formed in a partial region of the n-type GaAs layer 63 by vapor deposition.

  The p-type InGaAs layer 3 and the p-type GaAs layer 4 constitute a strain layer 5. The p-type GaAs layer 61, the non-doped GaAs layer 62 and the n-type GaAs layer 63 constitute the PIN photodiode 6. These release layer 2, p-type InGaAs layer 3, p-type GaAs layer 4, etching stop layer 7, p-type GaAs layer 61, non-doped GaAs layer 62 and n-type GaAs layer 63 are formed by MBE method (molecular beam epitaxial growth method), It is formed using an epitaxial growth technique such as MOCVD (metal organic chemical vapor deposition) or CVD (chemical vapor deposition).

  The p-type InGaAs layer 3 has a thickness of several nm to several tens of nm, and the p-type GaAs layer 4 has a thickness of several nm to several tens of nm. The lattice constant of the p-type InGaAs layer 3 is larger than the lattice constant of the p-type GaAs layer 4. Therefore, strain due to the difference in lattice constant occurs in the strained layer 5.

The thickness of the etching stopper layer 7 made of p-type Al _Y Ga _1-Y As is 100 nm, the thickness of the p-type GaAs layer 61 is 200 nm, and the thickness of the non-doped GaAs layer 62 is 1000 nm. The thickness of the n-type GaAs layer 63 is 200 nm. The Al composition ratio X in the p-type Al _x Ga _1-X As of the release layer 2 is 0.9, for example, and the Al composition ratio Y in the p-type Al _Y Ga _1-Y As of the etching stop layer 7 is 0.5. is there.

  Thereafter, contact pads (electrodes; not shown) made of metal are formed on the upper surface of the n-type GaAs layer 63 and the back surface of the p-type GaAs substrate 1 by vapor deposition and annealing.

  Next, as shown in FIG. 4, a concave portion 10 that defines a curved region is formed in the PIN photodiode 6 and the etching stopper layer 7 by photolithography and etching. As the etching, a wet etching method or an RIE method (reactive ion etching method) can be used.

  Next, as shown in FIG. 5, the PIN photodiode 6, the etching stop layer 7, the strain layer 5, and the release layer 2 are formed in a substantially U shape so as to surround the wall formation region by photolithography and etching (FIG. 5A )) To form a groove 11. Thereby, the p-type GaAs layer 61A, the non-doped GaAs layer 62A and the n-type GaAs layer 63A of the PIN photodiode 6A surrounded by the groove 11 and the light absorber 8 are the p-type GaAs layer 61B of the surrounding PIN photodiode 6B, Separated from the non-doped GaAs layer 62B and the n-type GaAs layer 63B. The width w of the region separated by the region including the groove 11 is several tens of μm. Also in this case, the wet etching method or the RIE method is used as the etching.

  Thereafter, the release layer 2 under the strained layer 5 is selectively etched by a wet etching method. As a result, as shown in FIG. 6, the strain layer 5 is located below the recess 10 so as to relieve strain caused by the difference in lattice constant between the p-type InGaAs layer 3 and the p-type GaAs layer 4 constituting the strain layer 5. It is curved in the region 12. In this case, the PIN photodiode 6A is fixed to the p-type GaAs substrate 1 by optimally selecting the thickness of the p-type InGaAs layer 3, the thickness of the p-type GaAs layer 4, and the In composition ratio in the p-type InGaAs layer 3. Can be erected vertically.

  For example, the thickness of the p-type InGaAs layer 3 is 10 nm, and the thickness of the p-type GaAs layer 4 is 10 nm. When the In composition ratio in the p-type InGaAs layer 3 is 0.2, the strained layer 5 stands upright with respect to the p-type GaAs substrate 1.

  By changing the In composition ratio in the p-type InGaAs layer 3, the difference in lattice constant between InGaAs and GaAs can be changed to about 7%.

  The following relationship exists among the thickness t1 of the p-type InGaAs layer 3, the thickness t2 of the p-type GaAs layer 4, the In composition ratio in the p-type InGaAs layer 3, and the curvature radius R of the strained layer 5.

R = (a / Δa) · (d / 2)
Here, a is a lattice constant of GaAs and is 5.6533 Å. Δa is the difference between the lattice constant of InGaAs and the lattice constant of GaAs. The lattice constant of In _0.2 Ga _0.8 As is 5.7343. D is the total of the thickness t1 of the p-type InGaAs layer 3 and the thickness t2 of the p-type GaAs layer 4. When t1 = t2 = 10 [nm], d = 20 [nm]. In this example, R = 0.329 [μm].

  In this way, the wall portions 301 to 304 made of the PIN photodiode 6A having the light absorber 8 on the surface and standing upright with respect to the surface of the GaAs substrate 1 are produced (see FIG. 1).

  Next, FIG. 7 is a schematic diagram for explaining the effect of the light absorber 8 of the direction detection element shown in FIG.

  As shown in FIG. 7, a part of the light emitted from a certain position enters the PIN photodiode 6B. Of the light not incident on the PIN photodiode 6B, the light incident on the light absorber 8 provided on the surface of the PIN photodiode 6A is absorbed by the light absorber 8 and does not reflect in the direction of the PIN photodiode 6B. . Further, since the PIN photodiode 6A is usually thin, part of the light is transmitted. For example, when light is incident from the surface of the PIN photodiode 6A where the light absorber 8 is not formed, if the light absorber 8 is not formed, the light passes through the PIN photodiode 6A, and some of the light is absorbed. Light enters the PIN photodiode 6B. However, if the light absorber 8 is formed, light transmitted from the side where the light absorber 8 is not formed can be blocked. Thereby, only the directly irradiated light is incident on the PIN photodiode 6B. Therefore, in the direction detection element of FIG. 1, it is possible to prevent light reflected by the walls 301 to 304 from entering the light receiving regions 101 to 104 of the PIN photodiode. As a result, it is possible to accurately detect the direction of light based on the current flowing through the PIN photodiode.

  In addition, the direction detection element of the first embodiment can be easily and inexpensively manufactured by planar technology such as normal photolithography, etching, epitaxial growth, and the like.

  The material of the light absorber 8 is not limited to carbon, and other various materials can be used.

  Alternatively, the strained layer 5 may be heated by passing a current through the strained layer 5. Thereby, the degree of curvature of the strained layer 5 can be adjusted, and the angles of the wall portions 301 to 304 can be changed. Also, the strained layer 5 can be easily bent by thermally expanding the p-type InGaAs layer 3.

  It is also possible to change the angle of the walls 301 to 304 to an angle other than a right angle by changing the voltage applied to the strained layer 5 or the current passed through the strained layer 5.

  Since the direction detection element of the present embodiment is constituted by a plurality of semiconductor layers and an upright structure of the semiconductor layers, the size and thickness can be reduced.

  In addition, a relatively large electrical signal can be obtained with a small-sized PIN photodiode. Therefore, the intensity of necessary incident light is reduced, and the size and thickness can be further reduced.

(Second Embodiment)
FIG. 8 is a schematic perspective view of a direction detection element according to the second embodiment of the present invention. In the direction detection element according to the second embodiment, a reflecting member 6C is formed on the surface of each wall portion 301 to 304 according to the first embodiment instead of the light absorber 8.

  FIG. 9 is a schematic cross-sectional view of one wall portion of the direction detection element shown in FIG.

As shown in FIG. 9, the direction detecting element in the second embodiment includes a release layer 2 made of p _- type Al _x Ga _1-x As, a p-type InGaAs layer 3, and a p-type on a p-type GaAs substrate 1. GaAs layer 4, etching stop layer 7 made of p _- type Al _Y Ga _1-Y As, release layer 2a made of p _- type Al _x Ga _1-x As, p-type InGaAs layer 3a, p-type GaAs layer 4a, p-type GaAs The layer 61, the non-doped GaAs layer 62, and the n-type GaAs layer 63 are sequentially stacked. At this time, an etching stop layer 7 a may be provided between the p-type GaAs layer 4 a and the p-type GaAs layer 61. The p-type InGaAs layer 3 and the p-type GaAs layer 4 constitute a strained layer 5, and the p-type InGaAs layer 3a and the p-type GaAs layer 4a constitute a strained layer 5a.

  The wall portion of the direction detection element shown in FIG. 9 is manufactured in the same manner as the steps of FIGS. 3 to 6 of the first embodiment. Similar to the first embodiment, the concave portion 10 and the groove 11 are formed, and the release layer 2 under the strained layer 5 is selectively etched by a wet etching method, so that the strained layer 5 is a region below the concave portion 10. Curve at 12. Further, the recess 10a is formed by removing the n-type GaAs layer 63, the non-doped GaAs layer 62, and the p-type GaAs layer 61, and the groove 11a is formed by removing from the n-type GaAs layer 63 to the etching stop layer 7. By selectively etching the release layer 2a under the strained layer 5a by the wet etching method, the strained layer 5a is curved in the region 12a below the recess 10a. As a result, a reflecting member 6C composed of the p-type GaAs layer 61, the non-doped GaAs layer 62, and the n-type GaAs layer 63 is formed.

  In this case, by selecting the thickness of the p-type InGaAs layer 3, the thickness of the p-type GaAs layer 4, and the In composition ratio in the p-type InGaAs layer 3, the strained layer 5 is fixed to the p-type GaAs substrate 1. Can stand upright. Further, by selecting the thickness of the p-type InGaAs layer 3a, the thickness of the p-type GaAs layer 4a, and the In composition ratio in the p-type InGaAs layer 3a, the p-type GaAs layer 61, the non-doped GaAs layer 62, and the n-type The reflecting member 6 </ b> C made of the GaAs layer 63 can be raised with respect to the p-type GaAs substrate 1 at an angle of about 45 degrees.

  FIG. 10 is a schematic diagram for explaining the effect of the reflecting member 6C of the direction detection element shown in FIG.

  As shown in FIG. 10, a part of the light emitted from a certain position enters the PIN photodiode 6B. Of the light not incident on the PIN photodiode 6B, the light incident on the wall is reflected in a direction different from the PIN photodiode 6B by the reflecting member 6C. Thereby, only the directly irradiated light is incident on the PIN photodiode 6B. Therefore, in the direction detection element of FIG. 8, it is possible to prevent light reflected by the walls 301 to 304 from entering the light receiving regions 101 to 104 of the PIN photodiode. As a result, it is possible to accurately detect the direction of light based on the current flowing through the PIN photodiode.

(Third embodiment)
FIG. 11 is a schematic perspective view of a direction detection element according to the third embodiment of the present invention. In the direction detection element in the third embodiment, the irregular reflection member 6 </ b> D having an uneven surface is formed on the surface of each wall portion 301 to 304 in the first embodiment instead of the light absorber 8.

  12 is a schematic cross-sectional view of one wall portion of the direction detection element shown in FIG.

As shown in FIG. 12, the direction detecting element according to the third embodiment includes a release layer 2, a p-type InGaAs layer 3, and a p-type made of p-type Al _x Ga _1-x As on a p-type GaAs substrate 1. It has a laminated structure in which the GaAs layer 4, the etching stop layer 7 made of p _- type Al _Y Ga _1-Y As, the p-type GaAs layer 61, the non-doped GaAs layer 62, and the n-type GaAs layer 63 are epitaxially grown in this order.

  The wall portion of the direction detection element shown in FIG. 12 is manufactured in the same manner as the steps of FIGS. 3 to 6 of the first embodiment. In the third embodiment, the surface of the separated n-type GaAs layer 63 is subjected to wet etching or dry etching to form an uneven surface. Thereby, the irregular reflection member 6D including the p-type GaAs layer 61, the non-doped GaAs layer 62, and the n-type GaAs layer 63 is formed.

  Thereafter, as in the first embodiment, the recess 10 and the groove 11 are formed, and the release layer 2 under the strain layer 5 is selectively etched by a wet etching method so that the strain layer 5 is located below the recess 10. It is curved in the region 12. Thereby, the irregular reflection member 6D including the p-type GaAs layer 61, the non-doped GaAs layer 62, and the n-type GaAs layer 63 is formed.

  Next, FIG. 13 is a schematic diagram for explaining the effect of the irregular reflection member 6D of the direction detection element shown in FIG.

  As shown in FIG. 13, a part of the light emitted from a certain position enters the PIN photodiode 6B. Of the light not incident on the PIN photodiode 6B, the light incident on the irregular reflection member 6D is irregularly reflected in a wide direction by the irregular surface of the irregular reflection member 6D. A part of the light incident from the surface opposite to the surface on which the irregular reflection member 6D is provided passes through the irregular reflection member 6D, but the transmitted light is irregularly reflected in a wide direction by the uneven surface of the irregular reflection member 6D. Thereby, only the light directly irradiated is incident on the PIN photodiode 6B. Therefore, in the direction detection element shown in FIG. 11, the light irregularly reflected by the walls 301 to 304 does not easily enter the light receiving regions 101 to 104 of the PIN photodiode. As a result, it is possible to accurately detect the direction of light based on the current flowing through the PIN photodiode.

(Other variations)
In the above embodiment, the four wall portions and the four photodiodes are arranged radially at an angular interval of 90 degrees around the reference point, but the number of the wall portions and the photodiodes is limited to this. Instead, other numbers of walls and photodiodes may be provided. For example, three walls and three photodiodes may be arranged radially at an angular interval of 120 degrees around the reference point. Also in this case, the elevation angle and azimuth angle of incident light can be detected based on the currents flowing through the three photodiodes.

  One photodiode may be arranged along one wall portion. In that case, the elevation angle of the incident light can be detected.

  Further, as the light receiving element, another light receiving element such as a phototransistor may be used instead of the PIN photodiode.

Furthermore, in the above-described embodiment, a stacked structure of a p-type InGaAs layer and a p-type GaAs layer is used as the strained layer. However, the present invention is not limited to this, and a combination of various semiconductor layers having different lattice constants is used. Can do. As the strained layer 5, another layered structure of III-V compound semiconductor or a layered structure of II-VI compound semiconductor may be used. Alternatively, a stacked structure of semiconductor layers containing Si (silicon) and Ge (germanium) may be used as the strained layer. Further, SiO ₂ may be used as the release layer.

  In the above embodiment, a GaAs substrate is used. However, other substrates such as a Si substrate may be used in consideration of the material of the release layer, the strained layer, and the PIN photodiode.

  Furthermore, in the above embodiment, AlGaAs is used as the material for the release layer, but the material is not limited to this, and other materials may be used in consideration of selective etching.

  The material of the PIN photodiode is not limited to the above embodiment, and other materials such as Si can be used.

  Next, a simulation was performed on the detection angle of the direction detection element shown in FIG.

In this simulation, the current values in the light receiving regions ₁₀₁ , ₁₀₂ , ₁₀₃ , and ₁₀₄ are indicated by I ₁₀₁ , I ₁₀₂ , I ₁₀₃ , and I ₁₀₄ . Further, when light is emitted to the direction detection element from a light source having an elevation angle φ of 90 degrees, I ₁₀₁ = I ₁₀₂ = I ₁₀₃ = I ₁₀₄ = 1. In this simulation, the light emitted from the light source is parallel light.

  Under the above conditions, the detection angle of the direction detection element was simulated when light was irradiated from the direction where the azimuth angle (azimuth angle) θ was 0 degree and the elevation angle φ was 30 degrees. The simulation results are shown in Table 1.

As shown in Table 1, when there is no reflected light from each of the wall portions 301 to 304, the relationship is I ₁₀₁ = I ₁₀₃ = I ₁₀₄ <I ₁₀₂ . In this case, the current values I ₁₀₁ and I ₁₀₃ I ₁₀₄ are 0.50, and the current value I ₁₀₂ is 0.07.

On the other hand, if there is a reflected light from the walls 301 to 304, the current value I ₁₀₄ is increased to 0.72. Here, the average value of the current values I ₁₀₃ and I ₁₀₄ was used as the current value I ₁₀₀ when the received light amount was the maximum, and the light detection direction was calculated using the above equations (1) and (2). As a result, the azimuth angle (azimuth angle) θ is 11.23 degrees, and the error is 11.23 degrees. The elevation angle φ is 28.96 degrees, and the error is −1.03 degrees.

Also, if there is a reflected light and transmitted light from the walls 301 to 304, the current value I ₁₀₄ is increased to 0.72, the current value I ₁₀₂ is increased to 0.29. As a result, the azimuth angle (azimuth angle) θ is 18.49 degrees, and the error is 18.49 degrees. The elevation angle φ is 42.03 degrees and the error is 12.03 degrees.

  In addition, under the same conditions, the detection angle of the direction detection element was simulated when light was irradiated from the direction where the azimuth angle (azimuth angle) θ was 0 degree and the elevation angle φ was 40 degrees. The simulation results are shown in Table 2.

As shown in Table 2, when there is no reflected light from each of the walls 301 to 304, the current values I ₁₀₁ , I ₁₀₃ , and I ₁₀₄ are 0.64, and the current value I ₁₀₂ is 0.26.

On the other hand, if there is a reflected light from the walls 301 to 304, the current value I ₁₀₄ is increased to 0.81. Here, the average value of the current values I ₁₀₃ and I ₁₀₄ was used as the current value I ₁₀₀ when the received light amount was the maximum, and the light detection direction was calculated using the above equations (1) and (2). As a result, the azimuth angle (azimuth angle) θ is 10.30 degrees, and the error is 10.30 degrees. Further, the elevation angle φ was 37.51 degrees, and the error was −2.49 degrees.

When there is reflected light and transmitted light from each of the walls 301 to 304, the current value I ₁₀₄ increases to 0.81 and the current value I ₁₀₂ increases to 0.45. As a result, the azimuth angle (azimuth angle) θ is 16.87 degrees, and the error is 16.87 degrees. The elevation angle φ is 51.24 degrees, and the error is 11.24 degrees.

  From the above results, it was found that a large error occurs in the light detection direction when the reflected light from each of the walls 301 to 304 enters the PIN photodiode. Therefore, in the direction detection element according to the embodiment of the present invention, the reflected light and transmitted light from the walls 301 to 304 are prevented from entering the PIN photodiode, so that the direction of the incident light can be accurately detected. You can see that

  According to the present invention, information related to the incident direction of light can be used as an electrical signal.

It is a typical perspective view of the direction detection element in the 1st Embodiment of this invention. FIG. 2 is a schematic plan view of the direction detection element in FIG. 1. FIG. 2 is a schematic cross-sectional view and a schematic plan view showing a method for manufacturing the direction detection element of FIG. 1. FIG. 2 is a schematic cross-sectional view and a schematic plan view showing a method for manufacturing the direction detection element of FIG. 1. FIG. 2 is a schematic cross-sectional view and a schematic plan view showing a method for manufacturing the direction detection element of FIG. 1. FIG. 2 is a schematic cross-sectional view and a schematic plan view showing a method for manufacturing the direction detection element of FIG. 1. It is a schematic diagram for demonstrating the effect of the light absorber of the direction detection element shown in FIG. It is a typical perspective view of the direction detection element in the 2nd Embodiment of this invention. It is typical sectional drawing of one wall part of the direction detection element shown in FIG. It is a schematic diagram for demonstrating the effect of the reflection member of the direction detection element shown in FIG. It is a typical perspective view of the direction detection element in the 3rd Embodiment of this invention. It is typical sectional drawing of one wall part of the direction detection element shown in FIG. It is a schematic diagram for demonstrating the effect of the irregular reflection member of the direction detection element shown in FIG. FIG. 5 is a schematic cross-sectional view showing a positional relationship between a wall portion standing vertically in a direction detection element and a light receiving region of a photodiode. FIG. 5 is a schematic cross-sectional view showing a positional relationship between a wall portion standing vertically in a direction detection element and a light receiving region of a photodiode. FIG. 5 is a schematic cross-sectional view showing a positional relationship between a wall portion standing vertically in a direction detection element and a light receiving region of a photodiode.

Explanation of symbols

1 p-type GaAs substrate 2, 2a release layer 3, 3a p-type InGaAs layer 4, 4a p-type GaAs layer 5, 5a strained layer 6, 6A, 6B PIN photodiode 6C reflective member 6D irregular reflection member 7 etching stop layer 8 light absorption Body 10 Recess 11 Groove 21 Curved portion 61, 61A, 61B p-type GaAs layer 62, 62A, 62B Non-doped GaAs layer 63, 63A, 63B n-type GaAs layer 101, 102, 103, 104 Light receiving region 201, 202, 203, 204 Contact pad 301, 302, 302, 304 Wall part 301a, 302a, 303a, 304a, 301b, 302b, 303b, 304b Auxiliary part

Claims (6)

A first layer, a second layer, and a third layer are sequentially formed on a substrate, and the second layer is smaller than the first semiconductor layer having the first lattice constant and the first lattice constant. Including a stacked structure with a second semiconductor layer having a second lattice constant,
A light shielding part forming region is disposed in the third layer, and a light receiving region of a light receiving element is formed in the third layer along one side of the light shielding forming region,
The third layer, the second layer, and the first layer are removed except for a part of a region surrounding the light shielding portion forming region of the third layer, and The light shielding portion forming region and the first layer in the partial region are removed, the third layer in the partial region is removed, and the second layer in the light shielding portion forming region is the partial region. A light-shielding portion that rises along the light-receiving area of the light-receiving element is formed by bending, and a reduction unit that reduces light incident on the light-receiving area of the light-receiving element from the light reflected by the light-shielding section is provided A direction detecting element. A first layer, a second layer, and a third layer are sequentially formed on a substrate, and the second layer is smaller than the first semiconductor layer having the first lattice constant and the first lattice constant. Including a stacked structure with a second semiconductor layer having a second lattice constant,
A plurality of light shielding portion forming regions are arranged at equiangular intervals around a predetermined reference point in the third layer, and a plurality of light receiving elements are arranged in the third layer along one side of each of the plurality of light shielding forming regions. Each light receiving area is formed,
The third layer, the second layer, and the first layer are removed except for a part of each of the regions surrounding the plurality of light shielding portion forming regions of the third layer. In addition, the plurality of light shielding portion forming regions and the first layer in each of the partial regions are removed, the third layer of each of the partial regions is removed, and the plurality of light shielding portion forming regions The second layer is curved in each of the partial regions, thereby forming a plurality of light-shielding portions that stand along the light-receiving regions of the plurality of light-receiving elements. Of the light reflected by the light-shielding portions, A direction detecting element comprising a reducing means for reducing light incident on a light receiving region of a plurality of light receiving elements. The plurality of light shielding portions are flat with respect to the light receiving regions of the plurality of light receiving elements, and the flat portions with respect to the flat portions so as to support the flat portions at a predetermined angle with respect to the third layer. The direction detecting element according to claim 2, further comprising a support portion that is curved. The reducing means is
The direction detection element according to claim 1, further comprising an absorber that is provided on a surface of the light shielding portion and absorbs light. The reducing means is
5. The direction detection element according to claim 1, wherein the direction detection element includes an uneven surface that is formed on a surface of the light shielding portion and diffusely reflects light. The reducing means is
The direction detection element according to any one of claims 1 to 3, further comprising a reflection member provided on a surface of the light shielding part and configured to reflect light in a direction different from a light receiving region of the light receiving element.

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