JP5402893B2 - Optical sensor - Google Patents

Description

  In the present invention, a plurality of light receiving elements that convert light into an electrical signal are formed on a semiconductor substrate, and 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. The present invention relates to an optical sensor in which a plurality of light openings are formed.

  Conventionally, for example, as disclosed in 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 a light-blocking property is provided on the upper surface of the light-transmitting layer. There has been proposed an optical sensor in which a light shielding mask is formed and a plurality of light propagation areas are formed on the light shielding mask. In this optical sensor, the elevation angle 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

  Incidentally, in the optical sensor disclosed in Patent Document 1, a single light-shielding mask is formed on the upper surface of the light-transmitting layer. In the case of this configuration, light incident from a certain light propagation area may be incident on a photodiode that does not correspond to the light propagation area via the light transmitting layer. For this reason, there is a concern that the output signal of the photodiode may include an optical output (disturbance output) from an unintended light propagation area.

  In view of the above problems, an object of the present invention is to provide an optical sensor in which disturbance output is suppressed from being included in an output signal of a light receiving element.

In order to achieve the above-described object, in the invention described in claim 1, a plurality of light receiving elements that convert light into electric signals are formed on one surface side of a semiconductor substrate, and on the surface of the semiconductor substrate on which the light receiving elements are formed, A light-shielding film is formed through the light-transmitting film, and a light-transmitting opening is formed in the light-shielding film corresponding to each of the light-receiving elements. By the opening, lines and light parallel to the light-receiving surface of the light-receiving element are formed. A light sensor having a light shielding portion that prevents light incident from an opening corresponding to a certain light receiving element from entering an adjacent light receiving element. The light-shielding portion has a light-shielding wall that reaches the light-shielding film from the formation surface of the light-receiving element in the semiconductor substrate, and the light-shielding wall is formed on the light- transmitting film so as to straddle the opposing regions of the adjacent openings. It is characterized by being.

As described above, according to the present invention, the light shielding wall is formed on the translucent film so as to straddle the opposing regions of the adjacent openings. According to this, light incident from a certain opening is suppressed from entering a light receiving element that does not correspond to the opening . That is, it is possible to block light propagation in a region between adjacent openings. Therefore , it is suppressed that the light output (disturbance output) from the opening part which is not intended is included in the output signal of each light receiving element.

As described in claim 2, it is preferable that the light shielding wall has an annular shape, and the periphery of the opening is surrounded by the annular light shielding wall. According to this, it is suppressed that the light which entered from the opening part surrounded by the light-shielding wall enters into the light receiving element not corresponding to the opening part. Further, the light incident from the opening adjacent to the opening surrounded by the light shielding wall is prevented from entering the light receiving element corresponding to the opening surrounded by the light shielding wall. In other words, light incident from the edge side of the semiconductor substrate is prevented from entering the light receiving element corresponding to the opening surrounded by the light shielding wall.

In addition, as described in claim 3 , the light shielding film and the light shielding wall preferably have conductivity. As described in claim 1 , since the light shielding film and the semiconductor substrate are connected via the light shielding wall, the light shielding film is utilized as wiring for electrically connecting electronic elements formed on the semiconductor substrate. be able to.

According to a fourth aspect of the present invention, the light shielding part has a light absorbing film having a property of absorbing light, and the light absorbing film is preferably formed on the surface of the light shielding film. According to this, light incident on the light-transmitting film through the opening is repeatedly reflected at the interface between the light-transmitting film and the semiconductor substrate or the interface between the light-transmitting film and the light-shielding film, thereby Propagation in the membrane is suppressed. Thereby, it is suppressed that the light which entered from a certain opening part enters into the light receiving element which does not correspond to the opening part, and it is suppressed that a disturbance output is included in the output signal of each light receiving element.

According to a fifth aspect of the present invention, it is preferable that the light absorbing film is formed at the end portion that forms the edge of the opening in the light shielding film.

According to the first aspect of the present invention, the elevation angle of the light is defined by the opening portion of the light shielding film. When light having an elevation angle smaller than the elevation angle is incident on the opening portion, a part of the light is shielded. The light is incident on an end portion constituting the edge of the opening in the film. Therefore, as described in claim 5 , by forming the light absorbing film at the end portion that forms the edge of the opening in the light shielding film, the disturbance light is suppressed from propagating through the light transmitting film.

According to the sixth aspect of the present invention, the end portion constituting the edge of the opening in the light shielding film is inclined so as to face the direction in which the light is incident, and the light absorbing film is formed on the inclined end portion. The structure in which is formed is good.

  According to this, since the area where the light is incident increases at the end portion constituting the edge of the opening in the light shielding film, it is more effectively suppressed that the disturbance light propagates through the light transmissive film. Furthermore, since the end portion described above is inclined so as to face the direction in which light enters, the light incident on the end portion is reflected without being absorbed by the light absorption film. The reflection direction can be the external direction. Thereby, disturbance light is more effectively suppressed from propagating through the translucent film.

According to a seventh aspect of the present invention, the light shielding film is preferably formed in multiple layers in the light transmissive film, and the elevation angle is defined by the openings formed in the light shielding film of each layer.

  According to this, the range of light incident on the semiconductor substrate is determined by the opening formed in the light shielding film of each layer. Accordingly, the range of light incident on the semiconductor substrate is narrowed compared to a configuration in which an opening is formed in a single light shielding film. Thereby, it is suppressed that the light which entered from the certain opening part enters into the light receiving element which does not correspond to the opening part. As a result, the disturbance signal is more effectively suppressed from being included in the output signal of each light receiving element.

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 a top view which shows the modification of an optical sensor. It is a top view which shows the modification of an optical sensor.

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. In FIG. 1, an edge constituting an opening 41 described later is indicated by a solid line, and a light shielding wall 51 is indicated by a broken line.

  As shown in FIGS. 1 and 2, the optical sensor 100 includes a semiconductor substrate 10, a light receiving element 20, a light transmissive film 30, a light shielding film 40, and a light shielding part 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 formation surface 10 a of the light receiving element 20, and the light shielding film 40 and the light shielding portion 50 are formed on the light transmitting film 30. Has been. The light-transmitting film 30 is formed with a light-transmitting opening 41, and light enters the light receiving element 20 through the opening 41. In FIG. 2, the light incident range in the translucent film 30 is shown as white.

  The semiconductor substrate 10 has a rectangular shape, and is formed with the above-described light receiving element 20 and electronic elements (not shown) constituting a circuit for processing an output signal of the light receiving element 20. These electronic elements are electrically connected via a wiring pattern 11 formed on the semiconductor substrate 10. As will be described later, the light shielding film 40 is made of a conductive material, and a part of the light shielding film 40 functions to electrically connect the electronic elements described above.

  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 FIG. 2, a plurality of light receiving elements 20 are formed on the semiconductor substrate 10 at a predetermined interval.

The translucent film 30 is made of a material having optical transparency and insulating properties. An example of a material having such properties is silicon oxide SiO ₂ . As shown in FIG. 2, the translucent film 30 is formed in multiple layers on the formation surface 10a. A through-hole 31 that penetrates in the thickness direction of the semiconductor substrate 10 is formed in each of the light-transmitting films 30 except the uppermost light-transmitting film 30 in the light-transmitting film 30. The through hole 31 is filled with a conductive member 53 described later. In the present embodiment, four translucent films 30 are formed on the formation surface 10a, and through holes 31 are formed in the three translucent films 30 on the formation surface 10a side.

  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 FIG. 2, 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. . In the present embodiment, three light shielding films 40 are formed in the light transmitting film 30, and an opening 41 corresponding to the light receiving element 20 is formed in each light shielding film 40 of each layer.

  In the present embodiment, the opening areas of the openings 41 formed in each light shielding film 40 are equal to each other, and a straight line parallel to the light receiving surface 20a of the light receiving element 20 and the light traveling direction are formed by the openings 41 of these layers. The elevation angle of the light formed by is defined. A part of the end 42 constituting the edge of the opening 41 is inclined so as to face the direction in which the light is incident, and the light shielding film 40 of each layer passes through a light shielding wall 51 described later. Are connected to each other.

  The light shielding unit 50 has a function of preventing light incident from the opening 41 corresponding to a certain light receiving element 20 from entering the light receiving element 20 adjacent thereto. The light shielding unit 50 includes a light shielding wall 51 and a light absorption film 52, and an opening 41 corresponding to a certain light receiving element 20 in the light transmitting film 30 and an opening corresponding to the light receiving element 20 adjacent thereto. 41. As shown by a broken line in FIG. 1, the light shielding wall 51 according to the present embodiment has a schematic planar shape that is annular, and surrounds the periphery of the opening 41 corresponding to one light receiving element 20. The transparent film 30 is formed. Thus, a part of the light shielding wall 51 is formed so as to straddle the opposing region of the adjacent opening 41, and the opposing region is crossed by the light shielding wall 51.

  The light shielding wall 51 is formed by filling the through hole 31 with a conductive material 53. The conductive material 53 is made of the same material as the light shielding film 40 and is integrally connected to the light shielding film 40. Thereby, the light shielding films 40 of the respective layers are mechanically and electrically connected via the light shielding walls 51. In the present embodiment, as shown in FIG. 2, the conductive member 53 that fills the through hole 31 of the translucent film 30 closest to the formation surface 10 a is electrically connected to the wiring pattern 11. Thereby, the light shielding film 40 and the wiring pattern 11 are electrically connected via the conductive member 53 (light shielding wall 51), and a part of the light shielding film 40 electrically connects each electronic element formed on the semiconductor substrate 10. It is supposed to fulfill the function of connecting to.

  The light absorption film 52 is made of a material that absorbs light. An example of a material having such properties is carbon. As shown in FIG. 2, the light absorption film 52 is formed on the upper surface 40 a of each light shielding film 40 and the end 42 constituting the edge of the opening 41.

  Next, functions and effects of the optical sensor 100 according to the present embodiment will be described. As described above, the light shielding wall 51 is formed on the translucent film 30 so as to straddle the opposing regions of the openings 41 adjacent to each other. According to this, since light incident from a certain opening 41 is suppressed from entering the light receiving element 20 that does not correspond to the opening 41, the output signal of each light receiving element 20 is output from an unintended opening 41. The light output (disturbance output) is not included.

  As shown in FIG. 1, the three light-transmitting films 30 on the formation surface 10 a side between a certain light receiving element 20 and the adjacent light receiving element 20 are shielded by the light shielding wall 51. Thereby, it is possible to completely shield light between a certain light receiving element 20 and the light receiving element 20 adjacent thereto by the light shielding wall 51.

  Further, in the present embodiment, the light shielding wall 51 is formed in the light-transmitting film 30 so as to surround the periphery of the opening 41 corresponding to one light receiving element 20, with a schematic planar shape being annular. . According to this, the light that has entered the opening 41 surrounded by the light shielding wall 51 is prevented from entering the light receiving element 20 that does not correspond to the opening 41. Further, light incident on an opening 41 (opening 41 on the left side of the drawing) different from the opening 41 surrounded by the light shielding wall 51 is incident on the light receiving element 20 corresponding to the opening 41 surrounded by the light shielding wall 51. Incident light is suppressed. More specifically, the light incident from the edge side of the semiconductor substrate 10 is suppressed from entering the light receiving element 20 corresponding to the opening 41 surrounded by the light shielding wall 51.

  The light shielding film 40 and the light shielding wall 51 (conductive member 53) have conductivity, and a part of the light shielding wall 53 is electrically connected to the wiring pattern 11. Thereby, the electronic elements formed on the semiconductor substrate 10 can be electrically connected via the light shielding wall 51 and the light shielding film 40.

  The light shielding unit 50 includes a light absorption film 52 having a property of absorbing light, and the light absorption film 52 is formed on the upper surface of the light shielding film 40. According to this, light incident on the light transmissive film 30 through the opening 41 is reflected at the interface between the light transmissive film 30 and the semiconductor substrate 10 or at the interface between the light transmissive film 30 and the light shielding film 40. , And the propagation through the light-transmitting film 30 is suppressed. Thereby, it is suppressed that the light which entered from the certain opening part 41 enters into the light receiving element 20 which does not correspond to the opening part 41, and it is suppressed that a disturbance output is included in the output signal of each light receiving element 20. .

  In the present embodiment, the light absorption film 52 is formed at the end 42 constituting the edge of the opening 41 in the light shielding film 40. When light having an elevation angle smaller than the elevation angle defined by the opening 41 of each layer of the light-shielding film 40 (for example, light indicated by a broken arrow in FIG. 2) enters the opening 41, a part of the light is The light enters the end portion 42 described above. Therefore, as shown in the present embodiment, by forming the light absorbing film 52 at the end portion 42, it is possible to suppress disturbance light from propagating through the light transmitting film 30.

  In this embodiment, a part of the end portion 42 is inclined so as to face the direction in which light is incident, and the light absorbing film 52 is formed on the inclined end portion 42. According to this, since the area where the light is incident at the end portion 42 increases, it is more effectively suppressed that the disturbance light propagates through the translucent film 30. Furthermore, since the above-described end portion 42 is inclined so as to face the light incident direction, the light incident on the end portion 42 is reflected without being absorbed by the light absorption film 52. The reflected direction of the emitted light can be the external direction (for example, the direction opposite to the dashed arrow). Thereby, disturbance light is more effectively suppressed from propagating through the translucent film 30.

  A translucent film 30 is formed on the formation surface 10 a of the semiconductor substrate 10, and a light shielding film 40 is formed in multiple layers on the translucent film 30. A light-transmitting opening 41 corresponding to each of the light receiving elements 20 is formed in the light shielding film 40 of each layer. According to this, the range of light incident on the semiconductor substrate 10 is narrowed by the opening 41 formed in the light shielding film 40 of each layer. As a result, light incident from a certain opening 41 is prevented from entering a light receiving element 20 that does not correspond to the opening 41. As a result, the output signal of each light receiving element 20 is more effectively suppressed from including a disturbance output.

  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 light transmissive film 30 is formed on the formation surface 10 a of the semiconductor substrate 10 and the light shielding films 40 are formed in multiple layers on the light transmissive film 30 is shown. However, the light shielding film 40 may be one layer. In this case, the through hole 31 is formed so as to reach one layer of the light shielding film 40 from the formation surface 10a, and the conductive member 53 is filled in the through hole 31 to form the light shielding wall 51.

  In the present embodiment, as indicated by a broken line in FIG. 1, the light shielding wall 51 is light-transmitting so that the schematic planar shape forms an annular shape and surrounds the periphery of the opening 41 corresponding to one light receiving element 20. The example formed in the film | membrane 30 was shown. However, the shape of the light shielding wall 51 and the formation position thereof are not limited to the above example. For example, as shown in FIG. 3, the light shielding wall 51 whose rough planar shape is U-shaped is included between the openings 41 corresponding to any two light receiving elements 20 in the translucent film 30. You may form in the area | region surrounding a part of circumference | surroundings of the opening part 41 corresponding to one light receiving element 20 in the translucent film | membrane 30. FIG. Alternatively, as shown in FIG. 4, a plurality of light blocking walls 51 whose rough planar shapes are rectangular are formed between the openings 41 corresponding to any two light receiving elements 20 in the light transmitting film 30. Thus, the opposing region of the adjacent openings 41 may be crossed by the plurality of light shielding walls 51. 3 and 4 are plan views showing modifications of the optical sensor.

  In the present embodiment, an example is shown in which a part of the end portion 42 constituting the edge of the opening 41 is inclined so as to face the direction in which light enters. However, all of the end portions 42 may be inclined so as to face the direction in which light enters.

  In the present embodiment, an example in which the light absorption film 52 is formed on the upper surface 40a of the light shielding film 40 is shown. However, the light absorption film 52 may be formed on the surface of the light shielding film 40. For example, the light absorption film 52 may be formed on the lower surface 40b of the light shielding film 40.

  In the present embodiment, an example in which the opening areas of the opening portions 41 of the respective layers are equal is shown. However, the opening area of the opening 41 of each layer may be different. For example, the opening area of the opening 41 of each layer may be reduced as it approaches the formation surface 10a.

  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 20a ... Light receiving surface 30 ... Translucent film 40 ... Light shielding film 41 ... Opening part 42 ... End part 50 ... Light shielding part 51 ... Light shielding wall 52 ... Light absorption film 100 ... Optical sensor

Claims (7)

A plurality of light receiving elements for converting light into an electrical signal are formed on one surface side of the semiconductor substrate, a light shielding film is formed on the light receiving element forming surface of the semiconductor substrate via a light transmitting film, and the light shielding film is formed on the light shielding film. A light-transmitting opening is formed corresponding to each of the light-receiving elements, and the opening defines the elevation angle of light formed by a line parallel to the light-receiving surface of the light-receiving element and the light traveling direction. Optical sensor,
A light shielding portion that prevents light incident from an opening corresponding to a certain light receiving element from entering a light receiving element adjacent thereto;
The light shielding portion has a light shielding wall that reaches the light shielding film from a formation surface of the light receiving element in the semiconductor substrate,
The optical sensor, wherein the light shielding wall is formed on the light-transmitting film so as to straddle a facing region of adjacent openings. The light shielding wall has an annular shape,
The optical sensor according to claim 1 , wherein the opening is surrounded by the annular light shielding wall. The optical sensor according to claim 1 , wherein the light shielding film and the light shielding wall have conductivity. The light shielding portion has a light absorbing film having a property of absorbing light,
The optical sensor according to claim 1 , wherein the light absorption film is formed on a surface of the light shielding film. The optical sensor according to claim 4 , wherein the light absorption film is formed at an end portion of the light shielding film that constitutes an edge of the opening. The optical sensor according to claim 5 , wherein an end of the light shielding film that constitutes an edge of the opening is inclined so as to face a direction in which light enters. The said light shielding film is formed in the said light-transmitting film in multiple layers, and an elevation angle is prescribed | regulated by the opening part formed in the light shielding film of each layer, The Claim 1 characterized by the above-mentioned. Optical sensor.

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