JPH0237995B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a one-chip optical angle detection device capable of detecting the direction of incidence of light.

Conventionally, a device for detecting the direction of a light emitting source such as the sun, as shown in FIGS. The incident direction of the light is detected using the ratio of the detected amounts of light incident on each of the photodetectors 1 to 4.

Therefore, in order to detect the incident direction of light with high accuracy, the relative angles of each of the inclined surfaces of the support body 5 need to be highly accurate. Furthermore, it has the disadvantage of requiring a plurality of photodetectors. For this reason,
It has been difficult to create a small, inexpensive optical angle detection device that can detect the direction of incidence of light with high precision.

In order to eliminate the above-mentioned drawbacks, the present invention forms an inclined surface different from the main surface of the substrate in one semiconductor substrate, and forms a photodetecting section on the inclined surface and the main surface of the substrate, thereby detecting light. The purpose is to achieve higher accuracy in angle detection and to reduce the size and cost of optical angle detection devices.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a sectional view of the optical angle detection device of the present invention. 6 is a single conductivity type semiconductor substrate or buried layer; 7
8 is a conductive type epitaxial layer, 8 is an electrode extraction region of the semiconductor substrate or buried layer 6, and 9 is <
A V-shaped recess formed in the epitaxial layer 7 having a 100> plane using an anisotropic etching process, 1
0 is a reverse conduction type impurity diffusion layer, 11 is an insulating layer, such as an oxide film, 12 is a light antireflection film, such as a nitride film, 13 is a wiring, and 15 is the V-shaped recess 9 on the left side.
The photodetecting section 16 having a photodetecting window on the inclined surface of
A photodetection section 17 has a photodetection window on the main surface of the epitaxial layer 7, a photodetection section 17 has a photodetection window on the inclined surface of the V-shaped recess 9 on the right side, and 14 refers to the photodetection sections 15 to 14. The light incident on 17 and 20 are the boundaries of the semiconductor chip located approximately at the center of the V-shaped recess. Incidentally, the semiconductor chip boundary may be at a position indicated by the semiconductor chip boundary 20'.

The manufacturing process of the photodetector is simply the addition of the anisotropic etching process and the process of forming the anti-reflection film to the normal bipolar process.

Next, the principle of operation will be explained.

The angle formed by the light 14 and a plane S perpendicular to the light detection unit 16 in the front-rear direction is an incident angle θ. However, when the light 14 enters from the left side of the vertical surface S,
θ0, and when incident from the right side, it is defined as θ0.

When the incident angle θ is θ0, the photodetector 1
5 and 16 to detect the incident angle θ of the light 14. The detection principle utilizes the fact that the inclinations of the photodetection surfaces of the photodetectors 15 and 16 are different by about 55 degrees, and the amount of incident light 14 of the photodetector 15 and the incident light of the photodetector 16 are determined with respect to the incident angle θ. The ratio Rl to the amount of 14 is
Use the following relationship.

Rl≒S ₁₅ /S ₁₆・cos(θ−55)/cosθ・η(θ−55)/
η(θ)...(1) Here, S ₁₅ is the area of the light receiving window of the photodetector 15, S ₁₆ is the area of the light receiving window of the photodetector 16, η
is the light-to-electricity conversion efficiency when the incident angle θ is θ.

Similarly, when the incident angle θ is θ0, the incident angle θ of the light 14 is detected using the photodetectors 17 and 16. It is utilized that the ratio Rr of the amount of incident light 14 to the photodetector 17 and the amount of incident light 14 to the photodetector 16 with respect to the incident angle θ is in the following relationship.

Rr≒S ₁₇ /S ₁₆・cos(θ+55)/cosθ・η(θ+55)/
η(θ)...(2) Here, _S17 is the area of the light receiving window of the photodetector 17. Usually, the areas S ₁₅ and S ₁₇ of the light receiving windows are:
Designed to have equal area.

Next, an integrated circuit using the optical angle detection device of the present invention will be explained using the block diagram of FIG.

When the light 14 enters the photodetectors 15 to 17,
Currents I _{15 to I 17 proportional to the amount of light incident on each of the photodetectors 15} to ₁₇ are output to the differential amplifier circuit 21 and the variable amplifier circuit 22. The differential amplifier circuit 2
1, the current I ₁₅ of the photodetector 15, 17,
The magnitude of I ₁₇ is compared. The current I ₁₅ is the current
If it is determined that the current I 16 of the photodetector 16 is larger than I ₁₇ , the output of the variable amplification circuit ₂₂ whose amplification degree is controlled by the current I 16 of the photodetector 16 is normalized by the current I ₁₆ of the photodetector 16. The photodetector 15
A signal voltage of the current I ₁₅ is outputted and applied to the A/D conversion circuit 23 . By the way, the current of the photodetector 17 is controlled by the differential amplifier circuit 21.
If it is determined that I ₁₇ is larger than the current I ₁₅ of the photodetector 15, the output of the variable amplifier circuit 22 is the photodetector normalized by the current I ₁₆ of the photodetector 16. A negative signal voltage of the current I ₁₇ of 17 is output and applied to the A/D conversion circuit 23 . The signal voltage having the sign is converted by the A/D conversion circuit 23 into, for example, an 8-bit digital signal including the sign, and outputted to the angle conversion circuit 24. The angle conversion circuit 24 retrieves data in the ROM 25 corresponding to the digital signal, and outputs, for example, an 8-bit digital angle signal including a code corresponding to the digital signal to the display conversion circuit 26. The data in the ROM 25 is as described in (1) and (2) above.
It is calculated using the formula. The display conversion circuit 26 converts the digital angle signal into a display signal and outputs it to, for example, a liquid crystal display device 27. Here, 15 to 17 and 21 to 26 can be formed on the same chip.

Figures 4a and 4b are front views of the optical angle detection device of the present invention. Photodetectors 18 and 19 are arranged perpendicularly to the photodetectors 15 and 17. By combining the angle signals obtained by the light detection units 15, 16, 17 and the angle signals obtained by the light detection units 16, 18, 19, the light 14 is transmitted to the front side of the light angle detection device. The direction of incidence of the light 14 can be detected from any direction.

As described above, according to the present invention, sloped surfaces having precise relative angles to each other using the characteristics of crystal planes are formed on the same chip using anisotropic etching technology, and each of the sloped surfaces is exposed to light. Because the detection section is arranged, it is possible to detect the incident direction of light with high precision, and the circuit that converts the light-to-current conversion signal of the photodetection section into incident angle information can also be mounted on the same chip. It has advantages such as being small and inexpensive.

[Brief explanation of drawings]

Figure 1a is a front view of a conventional optical angle detector;
Figure b is a side view of a conventional optical angle detector, and Figure 2 is a side view of a conventional optical angle detector.
FIG. 3 is a block diagram of an embodiment of an integrated circuit using the optical angle detection device of the present invention, and FIGS. 4a and 4b show the optical angle detection device of the present invention. FIG. 1-14, 15-19...Photodetection section, 5...Support, 6...Semiconductor substrate or buried layer, 7...Epitaxial layer, 8...Electrode extraction region, 9...
... V-shaped recess, 10 ... Impurity diffusion layer, 11 ... Insulating layer, 12 ... Anti-reflection film, 13 ... Wiring, 1
4...Light, 20,20'...Boundary of semiconductor chip,
21... Differential amplifier circuit, 22... Variable amplifier circuit,
23...A/D conversion circuit, 24...Angle conversion circuit, 25...ROM, 26...Display conversion circuit, 2
7...Liquid crystal display device, θ...Incidence angle, S...Vertical surface.

Claims (1)

[Scope of Claims] 1. A semiconductor substrate whose main surface is <100>; a photodetector provided on the main surface; a V-shaped recess formed on the surface of the substrate by an anisotropic etching technique; An optical angle detection device comprising a photodetector provided on a side surface of the V-shaped recess. 2. A plurality of V-shaped recesses are present in a mutually parallel positional relationship on the main surface portion of the substrate, and some of the V-shaped recesses have a first photodetecting portion only on one side of the V-shaped recess, Some of the remaining V-shaped recesses are
2. The optical angle detection device according to claim 1, further comprising a second light detection section only on a side surface that is in a positional relationship opposite to said one side surface. 3. Claim 2, further comprising another V-shaped recess and a group of photo-detecting parts provided in the other recess, in a positional relationship perpendicular to the group of photo-detecting parts provided in the V-shaped recess. Optical angle detection device as described in . 4. Claims 1 to 3, characterized in that the bottom surface of the V-shaped recess is located at the boundary with the adjacent chip.
2. The optical angle detection device according to any of the preceding paragraphs.