JP2012058140A - Optical sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical sensor that suppresses difficulties in detecting the intensity and angle of light by widening directivity.SOLUTION: The optical sensor includes a plurality of light receiving elements formed on one surface side of a semiconductor substrate and converting light into an electric signal, a translucent film formed on one surface of the semiconductor substrate, a light-shielding film formed on the one surface of the semiconductor substrate with the translucent film interposed, and a plurality of openings formed in the light-shielding film and introducing light into the corresponding light receiving elements. A first virtual straight line extending from the center of a first light receiving element to the center of a first opening corresponding to the first light receiving element, and a second virtual straight line extending from the center of a second light receiving element to the center of a second opening corresponding to the first light receiving element are different in at least one of an elevation angle and a right-left angle; and the light reception surface area of the first light receiving element is larger than the opening area of the first opening, and the light reception surface area of the second light receiving element is larger than the opening area of the second opening.

Description

  In the present invention, a plurality of light receiving elements for converting light into an electrical signal are formed on a semiconductor substrate, a light shielding film is formed on the surface of the semiconductor substrate on which the light receiving elements are formed via a light transmitting film, and the light receiving film receives light on the light shielding film. The present invention relates to an optical sensor in which a light-transmitting opening corresponding to each element is formed.

  Conventionally, as shown in, for example, Patent Document 1, a plurality of photodiodes are formed on a semiconductor substrate, a light-transmitting light-transmitting layer is formed on the formation surface, and the light-transmitting layer has a light-blocking property. There has been proposed an optical sensor in which a plurality of light propagation areas are formed on the light shielding mask. In this optical sensor, the range of light incident on the light receiving surface of the photodiode is defined by the light propagation area of the light shielding mask.

US Pat. No. 6,875,974

  By the way, in the optical sensor shown in Patent Document 1, as shown in FIG. 1 of Patent Document 1, the light receiving surface of the photodiode and the area of the light propagation area are substantially the same. For this reason, the angular range (directivity) of light incident on the light receiving surface of each photodiode is narrowed, and there is a risk that light having a certain angle cannot be detected by the photodiode. Therefore, in the case of the structure of the optical sensor described in Patent Document 1, it may be difficult to detect the intensity (incident amount) and angle (elevation angle and left / right angle) of light based on the output signal of each photodiode. is there.

  In view of the above problems, an object of the present invention is to provide an optical sensor in which it is difficult to detect the intensity and angle of light by widening directivity.

  In order to achieve the above-described object, the invention according to claim 1 is formed on one surface side of a semiconductor substrate, formed on one surface of the semiconductor substrate, and a plurality of light receiving elements for converting light into an electrical signal. A light-transmitting film having transparency, formed on one surface of the semiconductor substrate via the light-transmitting film, and having a light-shielding property, and formed on the light-shielding film, for introducing light into the corresponding light receiving element A light receiving element having a first light receiving element and a second light receiving element, wherein the opening corresponds to the first light receiving element. A first imaginary straight line having an opening and a second opening corresponding to the second light receiving element and extending from the center of the first light receiving element to the center of the first opening; and a second light receiving The second imaginary straight line extending from the center of the element to the center of the second opening is defined by at least one of an elevation angle and a left / right angle. The light receiving area of the first light receiving element is larger than the opening area of the first opening, and the light receiving area of the second light receiving element is larger than the opening area of the second opening. .

  Thus, according to the present invention, at least one of the elevation angle and the left-right angle of the virtual straight line connecting the center of the plurality of light receiving elements and the center of the opening corresponding to each light receiving element is different. Thereby, a plurality of output signals having different values including the light intensity and angle can be obtained.

  In the present invention, the light receiving area of the light receiving element is larger than the opening area of the corresponding opening. As a result, the angle range (directivity) of light incident on the light receiving surface of the light receiving element is widened compared to a configuration in which the light receiving area and the opening area are equal, and light having a certain angle cannot be detected by the light receiving element. The occurrence of the problem is suppressed. As described above, it is suppressed that it is difficult to detect the intensity (incident amount) and angle (elevation angle and left / right angle) of light based on the output signal of each light receiving element.

  By the way, in claim 1, an example in which two light receiving elements are formed on one surface side of the semiconductor substrate and two openings are formed in the light shielding film is shown. However, the numbers of the light receiving elements and the openings are not limited to the above example. For example, as described in claim 2, three light receiving elements may be formed on one surface side of the semiconductor substrate, and three openings may be formed in the light shielding film. According to a third aspect of the present invention, four light receiving elements may be formed on one surface side of the semiconductor substrate, and four openings may be formed in the light shielding film.

  In the present invention, the third imaginary straight line, the first imaginary straight line, and the second imaginary straight line extending from the center of the third light receiving element to the center of the third opening are respectively an elevation angle and a right and left angle. At least one of them is different, and the light receiving area of the third light receiving element is larger than the opening area of the third opening. According to a third aspect of the present invention, the fourth imaginary straight line extending from the center of the fourth light receiving element to the center of the fourth opening and the first to third imaginary straight lines are different in at least one of an elevation angle and a left / right angle. The light receiving area of the fourth light receiving element is larger than the opening area of the fourth opening.

  The intensity and angle of the light described above are performed by the calculation unit according to claim 4. The elevation angle described above is an angle formed by a straight line parallel to the light receiving surface of the light receiving element and the light traveling direction, and the left and right angles are angles around a reference point on the semiconductor substrate.

  According to a fifth aspect of the present invention, the light-shielding film is formed in multiple layers in the light-transmitting film, and the elevation angle of light is defined by the opening formed in the light-shielding film of each layer, and is formed in each light-shielding film of each layer A configuration in which the opening area of the formed opening portion increases as it approaches the formation surface of the semiconductor substrate is preferable.

  According to this, it is suppressed that the light which entered from a certain opening part enters into light receiving elements other than the light receiving element corresponding to the opening part. Thereby, it is suppressed that the disturbance signal from the unintended incident light is contained in the output signal of each light receiving element.

  In the present invention, the opening area of the opening formed in the light shielding film of each layer increases as the surface of the semiconductor substrate is formed. According to this, unlike the configuration in which the opening area of the opening portion of the light shielding film of each layer is equal, or the structure in which the opening area becomes smaller as approaching the formation surface, by the opening formed in each of the light shielding films of each layer, Narrowing of the directivity of light is suppressed.

It is a top view which shows schematic structure of the optical sensor which concerns on 1st Embodiment. It is sectional drawing which follows the II-II line | wire of FIG. It is sectional drawing which follows the III-III line of FIG. It is a schematic circuit diagram for demonstrating a calculation part. It is sectional drawing for demonstrating the angle range of light, (a) shows the angle range of this embodiment, (b) is the case where the light-receiving area of a light receiving element is equal to the opening area of a corresponding opening part The angle range is shown. It is a top view for demonstrating the modification of an optical sensor. It is a top view for demonstrating the modification of an optical sensor. It is sectional drawing which shows the modification of an opening part.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a plan view showing a schematic configuration of the photosensor according to the first embodiment. 2 is a cross-sectional view taken along line II-II in FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a schematic circuit diagram for explaining the calculation unit. 5A and 5B are cross-sectional views for explaining the angle range of light, where FIG. 5A shows the angle range of the present embodiment, and FIG. 5B shows the opening of the corresponding opening portion corresponding to the light receiving area of the light receiving element. The angle range when equal to the area is shown. In FIG. 1, light receiving elements 20 a to 20 c to be described later are indicated by broken lines, and in FIGS. 2 and 3, the range of light incident on the formation surface 10 a through the openings 41 a to 41 c in the light-transmitting film 30 is white. Shown as unplugged. Moreover, the calculation part 50 is abbreviate | omitted in FIGS. 1-3.

  As shown in FIGS. 1 to 4, the optical sensor 100 includes a semiconductor substrate 10, a light receiving element 20, a translucent film 30, a light shielding film 40, and a calculation unit 50 as main parts. The light receiving element 20 is formed on one surface side of the semiconductor substrate 10, the light transmitting film 30 is formed on the forming surface 10 a of the light receiving element 20, and the light shielding film 40 is formed on the light transmitting film 30. A light-transmitting opening 41 is formed in the light shielding film 40, and light enters the light receiving element 20 through the opening 41. The light receiving element 20 and the calculation unit 50 are electrically connected, and the output signal of the light receiving element 20 is processed by the calculation unit 50. In the following, first, after showing the schematic configuration of the main parts 10 to 50 of the optical sensor 100, the characteristic points of the optical sensor 100 and the functions and effects thereof will be described.

  The semiconductor substrate 10 has a rectangular shape, and the above-described light receiving element 20 and electronic elements (not shown) constituting the calculation unit 50 shown in FIG. 4 are formed. These electronic elements are electrically connected via a wiring pattern (not shown) formed on the semiconductor substrate 10.

  The light receiving element 20 converts light into an electrical signal. The light receiving element 20 according to this embodiment is a photodiode having a PN junction. As shown in FIGS. 1 to 3, three light receiving elements 20 a to 20 c are formed on the semiconductor substrate 10.

The translucent film 30 is made of a material having optical transparency and insulating properties. As a material having such a property, for example, there is an interlayer insulating film SiO ₂ used in a semiconductor process. As shown in FIGS. 2 and 3, the translucent film 30 is formed in multiple layers on the formation surface 10a. In the present embodiment, the three layers of light-transmitting film 30 are formed on the formation surface 10a.

  The light shielding film 40 is made of a material having light shielding properties and conductivity. An example of a material having such properties is aluminum. As shown in FIGS. 2 and 3, the light shielding film 40 is formed between the two light-transmitting films 30, and the multilayer light-shielding film 40 is formed on the formation surface 10 a via the light-transmitting film 30. Has been. In the present embodiment, two light shielding films 40 are formed on the light transmitting film 30, and openings 41 a to 41 c corresponding to the light receiving elements 20 a to 20 c are formed in the light shielding films 40 of the respective layers. In this embodiment, the opening areas of the openings 41a to 41c formed in each light shielding film 40 are equal, and the openings 41a to 41c of these layers are parallel to the light receiving surfaces 21 of the light receiving elements 20a to 20c. The elevation angle of light formed by the straight line and the traveling direction of light is defined. Although not shown, the light shielding film 40 is electrically connected to a wiring pattern formed on the semiconductor substrate 10 and functions as a wiring for electrically connecting each electronic element.

  The calculation unit 50 calculates the amount of incident light, the elevation angle, and the left and right angles of light incident on the optical sensor 100 based on the output signals of the light receiving elements 20a to 20c. As illustrated in FIG. 4, the calculation unit 50 calculates the output signals of the light receiving elements 20 a to 20 c and the amplification units 51 a to 51 c and the output signals of the amplification units 51 a to 51 c, thereby calculating the optical sensor 100. And an arithmetic unit 52 that calculates an incident amount, an elevation angle, and a left / right angle of incident light.

  Next, feature points and operational effects of the optical sensor 100 according to the present embodiment will be described. As shown in FIG. 1, the first light receiving element 20a is located at the reference point P of the semiconductor substrate 10 indicated by a cross. The second light receiving element 20b is positioned on a reference line Q that passes through the reference point P and is parallel to the forming surface 10a, and the third light receiving element 20c is 90 degrees clockwise with the reference point P as the rotation center. It is located on the rotated rotation line R. The first opening 41a corresponding to the first light receiving element 20a is located at the reference point P, the second opening 41b corresponding to the second light receiving element 20b is located on the reference line Q, and the third light receiving element 20c. The third opening 41c corresponding to is located on the rotation line R. Thus, when the angle (left and right angle) around the reference point P is defined as an angle formed by the reference line Q and an arbitrary line passing through the reference point P, the light receiving surfaces of the first light receiving element 20a and the second light receiving element 20b, respectively. The left and right angles of light incident on 21 are 0 °, and the left and right angles of light incident on the light receiving surface 21 of the third light receiving element 20c are 90 °.

  As shown in FIGS. 1-3, the center of the 1st light receiving element 20a and the center of the 1st opening part 41a are located in the reference point P, The 1st virtual straight line A which connects each center, and the formation surface 10a The angle (elevation angle) formed by is 90 °. On the other hand, the center of the second light receiving element 20b and the center of the second opening 41b are separated on the reference line Q so that the second light receiving element 20b is on the reference point P side. The elevation angle of the second virtual straight line B to be connected is 45 °. Further, the center of the third light receiving element 20c and the center of the third opening 41c are separated on the rotation line R so that the third light receiving element 20c is on the reference point P side, and the third connecting the respective centers. The elevation angle of the virtual straight line C is 45 °.

  As described above, the elevation angle of the first virtual straight line A is 90 °, the left-right angle is 0 °, the elevation angle of the second virtual straight line B is 45 °, the left-right angle is 0 °, the elevation angle of the third virtual straight line C is 45 °, and the left-right angle Is 90 °. Thereby, the angular range (directivity) of light incident on the light receiving surface 21 of the first light receiving element 20a includes an elevation angle of 90 ° and a left / right angle of 0 °, and the directivity of the second light receiving element 20b is an elevation angle of 45 ° and a left / right angle. Including 0 °, the directivity of the third light receiving element 20c includes an elevation angle of 45 ° and a horizontal angle of 90 °. As described above, in the case of the above configuration, three output signals having at least one of an elevation angle and a right and left angle can be obtained. Therefore, by calculating these three output signals by the calculation unit 50, the light intensity (incident Quantity) and angle (elevation angle and left / right angle) can be detected.

In addition, as shown in FIGS. 2, 3, and 5, the light receiving areas of the respective light receiving elements 20a to 20c are larger than the opening areas of the corresponding openings 41a to 41c. As a result, as shown in FIG. 5, the angle range (directivity) of the light incident on the light receiving surface 21 defined by the angle θ formed by the two lines indicated by the broken lines is such that the light receiving area and the opening area are It is wider than an equal configuration. That is, the angle θ ₁ is larger than the angle θ ₃ and the angle θ ₂ is larger than the angle θ ₄ . Accordingly, it is possible to suppress the occurrence of the problem that light having a certain angle cannot be detected by the light receiving element, and based on the output signals of the light receiving elements 20a to 20c, the light intensity (incident amount) and angle (elevation angle). And the left and right corners) are prevented from being difficult to detect.

  In the present embodiment, the light-shielding film 40 is formed in a multilayer on the light-transmitting film 30, and the multilayer light-shielding film 40 is formed between the adjacent openings 41. Thereby, the range of light incident on the semiconductor substrate 10 can be narrowed compared to a configuration in which an opening is formed in a single light-shielding film. Thereby, for example, light having an elevation angle indicated by a solid arrow in FIG. 2 is suppressed from entering the first light receiving element 20a that does not correspond to the second opening 41b via the second opening 41b. As a result, the output signal of each light receiving element 20 is suppressed from including disturbance output from unintended incident light.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In the present embodiment, an example in which the three light receiving elements 20 a to 20 c are formed on the semiconductor substrate 10 has been described. However, the number of light receiving elements 20 is not limited to the above example as long as it is plural. Further, when there are four or more light receiving elements 20 and corresponding opening portions 41, at least one of the elevation angle and the left and right angles of the virtual straight lines connecting the centers of the plurality of light receiving elements 20 and the corresponding opening portions 41, respectively. Should be different. For example, as shown in FIG. 6, four light receiving elements 20 a to 20 d are formed on the semiconductor substrate 10, or as shown in FIG. 7, eight light receiving elements 20 a to 20 h are formed on the semiconductor substrate 10. A configuration can also be adopted.

  In the modification shown in FIG. 6, the fourth light receiving element 20d and the fourth opening 41d are arranged on a rotation line S obtained by rotating the reference line Q by 90 ° (−90 °) counterclockwise with the reference point P as the rotation center. Is formed. Then, the center of the fourth light receiving element 20d and the center of the fourth opening 41d are separated on the rotation line S so that the fourth light receiving element 20d is on the reference point P side, and the fourth connecting the respective centers. The elevation angle of a virtual straight line (not shown) is 45 °. Thereby, the elevation angle of the fourth virtual straight line is 45 ° and the left-right angle is −90 °, and the directivity of the fourth light receiving element 20d includes the elevation angle of 45 ° and the left-right angle of −90 °. FIG. 6 is a plan view for explaining a modification of the optical sensor.

  In the modification shown in FIG. 7, the light receiving element 20 and the opening 41 are on a plurality of virtual straight lines (not shown) extending radially from the reference point P so that the opening 41 is on the reference point P side. The elevation angles defined by the openings 41a to 41h corresponding to the light receiving elements 20a to 20h are different. With the configuration shown in FIG. 7, light incident from the reference point P side can be detected by the eight light receiving elements 20 having different directivities. Thereby, the detection accuracy of the incident amount, the elevation angle, and the left and right angles of the light incident from the reference point P side can be increased. FIG. 7 is a plan view for explaining a modification of the optical sensor.

  In the present embodiment, an example in which the light transmissive film 30 has three layers and the light shielding film 40 has two layers has been described. However, the number of layers of each of the light-transmitting film 30 and the light-shielding film 40 is not limited to the above example. For example, as shown in FIG. 8, the light-transmitting film 30 has four layers and the light-shielding film 40 has three layers. Can also be adopted.

  In the present embodiment, an example in which the opening areas of the opening portions 41 of the light shielding films 40 of the respective layers are equal is shown. However, the opening area of the opening 41 of each layer may be different. For example, as shown in FIG. 8, the opening area of the opening 41 of each layer may increase as it approaches the formation surface 10a. In other words, the opening area of the opening 41 close to the formation surface 10a may be larger than the opening area of the opening 41 away from the formation surface 10a. According to this, unlike the configuration in which the opening areas of the opening portions 41 of the light shielding film 40 of each layer are equal or the configuration in which the opening area becomes smaller as the formation surface 10a is approached, each of the light shielding films 40 of each layer is formed. Due to the opening 41, the directivity of light is remarkably reduced (the range of light incident on the formation surface 10a is smaller than the light receiving area of the light receiving surface 21). FIG. 8 is a cross-sectional view showing a modification of the opening. In FIG. 8, the range of light incident on the formation surface 10 a through the opening 41 in the translucent film 30 is shown as white.

  In this embodiment, the example which the light shielding film 40 consists of a material which has light-shielding property and electroconductivity was shown. However, when the electronic elements formed on the semiconductor substrate 10 do not have to be electrically connected by the light shielding film 40, the light shielding film 40 may be formed of a material that absorbs light.

DESCRIPTION OF SYMBOLS 10 ... Semiconductor substrate 20 ... Light receiving element 21 ... Light receiving surface 30 ... Translucent film 40 ... Light shielding film 41 ... Opening part 100 ... Optical sensor

Claims (5)

A plurality of light receiving elements that are formed on one side of the semiconductor substrate and convert light into an electrical signal;
A light-transmitting film formed on one surface of the semiconductor substrate and having light transmittance;
A light-shielding film which is formed on one surface of the semiconductor substrate via the light-transmitting film and has a light-shielding property;
A plurality of openings formed in the light shielding film for introducing light into the corresponding light receiving elements,
The light receiving element includes a first light receiving element and a second light receiving element,
The opening has a first opening corresponding to the first light receiving element and a second opening corresponding to the second light receiving element;
A first virtual line extending from the center of the first light receiving element to the center of the first opening, and a second virtual line extending from the center of the second light receiving element to the center of the second opening. Is different from at least one of the elevation angle and the left and right angles,
The light receiving area of the first light receiving element is larger than the opening area of the first opening, and the light receiving area of the second light receiving element is larger than the opening area of the second opening. Optical sensor. The light receiving element has a third light receiving element together with the first light receiving element and the second light receiving element,
The opening has a third opening corresponding to the third light receiving element, together with the first opening and the second opening,
The third imaginary straight line extending from the center of the third light receiving element to the center of the third opening, the first imaginary straight line, and the second imaginary straight line each have at least one of an elevation angle and a right and left angle. Is different,
The light sensor according to claim 1, wherein a light receiving area of the third light receiving element is larger than an opening area of the third opening. The light receiving element has a fourth light receiving element together with the first to third light receiving elements,
The opening has a fourth opening corresponding to the fourth light receiving element together with the first to third openings.
The fourth imaginary straight line extending from the center of the fourth light receiving element to the center of the fourth opening and the first to third imaginary straight lines differ in at least one of an elevation angle and a right and left angle,
The light sensor according to claim 2, wherein a light receiving area of the fourth light receiving element is larger than an opening area of the fourth opening.   4. The optical sensor according to claim 2, further comprising a calculating unit that calculates an elevation angle, a left-right angle, and an incident amount of light incident on the semiconductor substrate based on an output signal of each light receiving element. . The light-shielding film is formed in multiple layers on the light-transmitting film, and an elevation angle of light is defined by an opening formed in the light-shielding film of each layer,
5. The optical sensor according to claim 1, wherein an opening area of an opening formed in the light shielding film of each layer increases as the surface of the semiconductor substrate is formed.

Images