JP2021136416A - Sensor element and sensor device - Google Patents

Abstract

To achieve a better sensing result.SOLUTION: A sensor element includes a photoelectric conversion part that receives light incident into a semiconductor substrate and performs photoelectric conversion, a separation part that optically separates the photoelectric conversion part by surrounding the periphery with a trench structure engraving the semiconductor substrate from a back surface side where light enters, a transfer part provided on a front surface side of the semiconductor substrate and transferring charges accumulated in the photoelectric conversion part, a charge accumulation part temporarily accumulating charges transferred from the photoelectric conversion part through the transfer part, and an opening part provided by opening a part of one side of the separation part that serves as a transfer path for the charges from the photoelectric conversion part to the charge accumulation part. The present technique is applicable to, for example, an indirect time of flight (TOF) sensor or infrared (IR) sensor.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a sensor element and a sensor device, and more particularly to a sensor element and a sensor device capable of obtaining better sensing results.

Conventionally, various sensor devices such as an indirect TOF (Time of Flight) sensor are configured by, for example, a plurality of sensor elements arranged in an array on a semiconductor substrate. Then, in the sensor device, the light received by the sensor element is photoelectrically converted in the photodiode, and the electric charge generated according to the amount of received light is transferred from the photodiode to the FD (Floating Diffusion) unit, and the charge corresponds to the potential. The signal is output from the sensor element.

For example, Patent Document 1 stores a charge discarding unit for resetting unnecessary charges existing in a photodiode and a charge read from the photodiode in a distance imaging device that receives incident light from the back surface side of the semiconductor substrate. A structure including a plurality of charge storage portions is disclosed as an overflow drain.

JP-A-2009-8537

By the way, conventionally, the back-illuminated type sensor element has a structure in which light shielding is not sufficiently performed on the FD portion, the memory area, etc. that accumulate the electric charge generated by the photoelectric conversion by the photodiode. Therefore, PLS (Parasitic Light Sensitivity), which shows the characteristic of sensitivity due to light leaking to the FD section or the memory area, has been a cause of deterioration. Therefore, it is required to improve PLS so that better sensing results can be obtained.

The present disclosure has been made in view of such a situation, and is intended to enable better sensing results to be obtained.

The sensor element on one side of the present disclosure has a photoelectric conversion unit that receives light emitted from the semiconductor substrate and performs photoelectric conversion, and a trench structure in which the semiconductor substrate is dug from the first surface side irradiated with the light. A separation unit that optically separates the photoelectric conversion unit and a second surface side of the semiconductor substrate that is opposite to the first surface are provided on the photoelectric conversion unit. A transfer unit that transfers the stored charge, a charge storage unit that temporarily stores the charge transferred from the photoelectric conversion unit via the transfer unit, and a charge from the photoelectric conversion unit to the charge storage unit. It is provided with an opening provided by opening a part of one side of the separation portion which is a transfer path of the above.

The sensor device on one side of the present disclosure has a photoelectric conversion unit that receives light emitted from the semiconductor substrate and performs photoelectric conversion, and a trench structure in which the semiconductor substrate is dug from the first surface side irradiated with the light. A separation unit that optically separates the photoelectric conversion unit and a second surface side of the semiconductor substrate that is opposite to the first surface are provided on the photoelectric conversion unit. A transfer unit that transfers the stored charge, a charge storage unit that temporarily stores the charge transferred from the photoelectric conversion unit via the transfer unit, and a charge from the photoelectric conversion unit to the charge storage unit. It is provided with a sensor element having an opening provided by opening a part of one side of the separation portion which is a transfer path of the above.

In one aspect of the present disclosure, the semiconductor substrate is separated by a trench structure that is photoelectrically converted by a photoelectric conversion unit that receives the light emitted to the semiconductor substrate and the semiconductor substrate is dug from the first surface side that is irradiated with the light. The photoelectric conversion unit is optically separated by the unit, and the electric charge accumulated in the photoelectric conversion unit is transferred by the transfer unit provided on the second surface side of the semiconductor substrate opposite to the first surface. The charge transferred from the photoelectric conversion unit via the transfer unit is temporarily accumulated in the charge storage unit, and a part of one side of the separation unit that serves as a charge transfer path from the photoelectric conversion unit to the charge storage unit is opened. An opening is provided with.

It is a block diagram which shows the structural example of one Embodiment of the sensor element to which this technique is applied. It is a figure explaining the mask pattern of the element separation structure. It is a figure which shows the three-dimensional configuration example of a sensor element. It is a figure which shows the structural example of the sensor element which is the 1st variation. It is a figure which shows the structural example of the sensor element which is the 2nd variation. It is a figure which shows the structural example of the sensor element which is a 3rd variation. It is a figure which shows an example of the laminated structure of a sensor element. It is a figure which shows the structural example of the sensor element which is a 4th variation. It is a figure which shows the structural example of the sensor element which is a 5th variation. It is a figure which shows the structural example of the sensor element which is a 6th variation. It is a figure which shows the structural example of the sensor element which is 7th variation. It is a figure which shows the structural example of the sensor element which is 8th variation. It is a block diagram which shows the structural example of a sensor device. It is a figure which shows the use example using an image sensor.

Hereinafter, specific embodiments to which the present technology is applied will be described in detail with reference to the drawings.

<Sensor element configuration example>
FIG. 1 is a diagram showing a configuration example of an embodiment of a sensor element to which the present technology is applied.

FIG. 1A shows a planar configuration example of the sensor element 11. B in FIG. 1 shows a cross-sectional configuration example of the sensor element 11 in the alternate long and short dash line AA shown in A of FIG. 1, and C in FIG. 1 shows the alternate long and short dash line B shown in A of FIG. A cross-sectional configuration example of the sensor element 11 in −B is shown.

As shown in FIG. 1, the sensor element 11 is incident on the photoelectric conversion unit 22 by an element separation structure 23 provided so as to surround the photoelectric conversion unit 22 that receives light incident on the semiconductor substrate 21 and performs photoelectric conversion. It is configured to be optically separated so that the emitted light does not leak to the outside. Further, the sensor element 11 is a transfer gate 24 that transfers the charge photoelectrically converted in the photoelectric conversion unit 22, and an FD unit that temporarily stores the charge transferred from the photoelectric conversion unit 22 via the transfer gate 24. 25 is provided on the surface side of the semiconductor substrate 21 outside the element separation structure 23. Then, in the sensor element 11, an opening 26 formed so as to open a part of the element separation structure 23 serving as a charge transfer path (white arrow in the figure) from the photoelectric conversion unit 22 to the FD unit 25 is provided. It is provided.

For example, the sensor element 11 has a rectangular shape in a plan view, and the transfer gate 24 and the FD unit 25 are arranged on one side of the rectangle. The opening 26 of the element separation structure 23 makes the digging depth in a part of one side of the element separation structure 23 in which the transfer gate 24 and the FD portion 25 are arranged shallower than the digging depth in the other part. Formed by

Specifically, the element separation structure 23 has a trench structure in which the semiconductor substrate 21 is dug from the back surface side, and of the four sides of the rectangular shape in a plan view, three other than the one side on which the opening 26 is provided. The sides are dug to a depth that penetrates the semiconductor substrate 21. In the element separation structure 23, on one side where the opening 26 is provided, the digging depth other than the opening 26 becomes a depth that penetrates the semiconductor substrate 21 like the other three sides, and the opening 26 is formed. The digging depth in is formed to be shallower than in other parts. That is, the element separation structure 23 does not have a shape in which the digging depth over all of one side on which the opening 26 is provided is shallower than the digging depth of the other three sides, but only a part of the digging depth. Has a shallow shape.

Further, as shown in B of FIG. 1, the opening 26 of the element separation structure 23 is formed so that the arc has a continuous curved shape, and gradually becomes shallower from both sides and curves at the deepest center. It is formed into a convex shape. With such a shape, the opening 26 can have a minimum necessary opening area according to the charge transfer path, for example, rather than a simple arch shape. As a result, the opening 26 can have a larger effect of preventing light from leaking out of the element separation structure 23 through the opening 26 due to the smaller opening area.

Further, the sensor element 11 has transistor forming regions 27-1 to 27 on the surface side of the semiconductor substrate 21 outside the element separation structure 23 along three sides other than one side where the transfer gate 24 and the FD portion 25 are provided. -3 is provided. In the transistor formation regions 27-1 to 27-3, various transistors necessary for driving the sensor element 11, such as an amplification transistor, a reset transistor, and a selection transistor, are formed.

Further, the sensor element 11 is the back surface of the semiconductor substrate 21, and the inter-element light-shielding film 28 and the on-chip lens 29 are on the light incident surface (the surface facing upward in FIGS. 1B and 1C) on which light is incident on the semiconductor substrate 21. Are laminated. The inter-element light-shielding film 28 blocks the boundary with another adjacent sensor element 11, and the on-chip lens 29 collects the light incident on the semiconductor substrate 21 on the photoelectric conversion unit 22. Further, the transfer gate 24 and the FD portion 25 are also shielded from light by the inter-element light-shielding film 28.

In the sensor element 11 having such a configuration, the light incident on the semiconductor substrate 21 is transmitted to the FD portion 25 by providing the element separation structure 23 with an opening 26 having the minimum necessary opening area according to the charge transfer path. It is possible to suppress leakage. As a result, the sensor element 11 can improve the PLS as compared with the conventional sensor element, and can obtain a better sensing result.

Here, with reference to FIG. 2, a mask pattern used when digging a trench structure to be an element separation structure 23 will be described.

In FIG. 2, the cross-hatched opening region 31 corresponds to the region where the mask pattern used for digging the trench structure to be the element separation structure 23 is open. Then, at the location where the opening 26 is provided in the element separation structure 23, a mask pattern is formed so that the line width of the opening region 31 becomes narrower. That is, a part of one side of the rectangular opening region 31 is the narrow region 32.

Then, when the semiconductor substrate 21 is etched with a mask pattern provided with such an opening region 31, the digging depth in the narrow region 32 becomes shallower than the opening region 31 in the other regions due to the microloading effect. The semiconductor substrate 21 is dug into the space. As a result, as shown in FIG. 1, it is possible to form the element separation structure 23 provided with the opening 26 having a curved shape with continuous arcs.

FIG. 3 is a diagram showing a three-dimensional configuration example of the sensor element 11.

As shown in FIG. 3, in the sensor element 11, an inter-element light-shielding film 28 is arranged so as to surround the sensor element 11 on the light incident surface of the semiconductor substrate 21, and the light incident on the semiconductor substrate 21 is emitted to the outside. The element separation structure 23 is provided so as to prevent leakage. Further, the sensor element 11 is a back-illuminated type in which light is irradiated from the back surface side of the semiconductor substrate 21, and the surface facing downward in FIG. 3 is the surface of the semiconductor substrate 21.

The sensor element 11 has a structure in which the entire outer periphery is optically separated by the element separation structure 23 in a deep portion where the depth from the surface side of the semiconductor substrate 21 is deep. Further, the sensor element 11 is provided with an opening 26 in a part of the element separation structure 23 in a shallow portion where the depth from the surface side of the semiconductor substrate 21 is shallow, and the element separation structure 23 other than the opening 26 is provided. The outer circumference is optically separated by the above.

<Variations of sensor elements>
Variations of the sensor element 11 will be described with reference to FIGS. 4 to 12.

FIG. 4 is a diagram showing a configuration example of the sensor element 11a, which is the first variation.

FIG. 4A shows a planar configuration example in the shallow portion of the sensor element 11a, and FIG. 4B shows a planar configuration example in the deep portion of the sensor element 11a. Further, C in FIG. 4 shows a cross-sectional configuration example of the sensor element 11a in the alternate long and short dash line AA shown in A and B in FIG. 4, and the surface facing downward in C in FIG. 4 is a semiconductor. It is the back surface (light incident surface) of the substrate 21. In the sensor element 11a shown in FIG. 4, the same reference numerals are given to the configurations common to the sensor element 11 of FIG. 1, and detailed description thereof will be omitted.

Similar to the sensor element 11 in FIG. 1, the sensor element 11a is provided with an element separation structure 23 so as to surround the photoelectric conversion unit 22 of the semiconductor substrate 21, and an opening 26 is provided in a part of one side of the element separation structure 23. Is formed.

Then, in the sensor element 11a, two transfer gates 24-1 and 24-2 and two FD portions 25-1 and 25-2 are provided on the surface side of the semiconductor substrate 21. That is, in the sensor element 11a, the electric charge is transferred to the FD unit 25-1 via the transfer gate 24-1 and the electric charge is transferred to the FD unit 25-2 via the transfer gate 24-2. The transfer path is configured to pass through the opening 26 of the element separation structure 23.

Further, in the sensor element 11a, like the sensor element 11 in FIG. 1, transistor forming regions 27-1 to 27-3 are provided on the surface side of the semiconductor substrate 21 outside the element separation structure 23.

Similar to the sensor element 11 in FIG. 1, the sensor element 11a having such a configuration is better by suppressing the leakage of light to the FD units 25-1 and 25-2 and improving the PLS. The sensing result can be obtained.

FIG. 5 is a diagram showing a configuration example of the sensor element 11b of the second variation.

FIG. 5A shows a planar configuration example in the shallow portion of the sensor element 11b, and FIG. 5B shows a planar configuration example in the deep portion of the sensor element 11b. Further, C in FIG. 5 shows a cross-sectional configuration example of the sensor element 11b in the alternate long and short dash line AA shown in A and B in FIG. 5, and the surface facing downward in C in FIG. 5 is a semiconductor. It is the back surface (light incident surface) of the substrate 21. In the sensor element 11b shown in FIG. 5, the same reference numerals are given to the configurations common to the sensor element 11a in FIG. 4, and detailed description thereof will be omitted.

Similar to the sensor element 11a of FIG. 4, the sensor element 11b is provided with an element separation structure 23b so as to surround the photoelectric conversion portion 22b of the semiconductor substrate 21, and an opening 26 is provided in a part of one side of the element separation structure 23b. Is formed. Further, in the sensor element 11b, the electric charge is transferred to the FD unit 25-1 via the transfer gate 24-1 and the electric charge is transferred to the FD unit 25-2 via the transfer gate 24-2. The transfer path is configured to pass through the opening 26 of the element separation structure 23b, which is the same configuration as the sensor element 11a of FIG.

Then, in the sensor element 11b, the element separation structure 23b has three sides other than the one provided with the transfer gates 24-1 and 24-2 and the FD portions 25-1 and 25-2 with the outer circumference of the sensor element 11b. It is provided so as to be arranged at a certain position. As a result, the sensor element 11b is configured such that the transistor forming regions 27-1 to 27-3 are provided on the surface side of the semiconductor substrate 21 inside the element separation structure 23b.

Similar to the sensor element 11a of FIG. 4, the sensor element 11b having such a configuration is better by suppressing the leakage of light to the FD units 25-1 and 25-2 and improving the PLS. The sensing result can be obtained.

Further, as compared with the sensor element 11a of FIG. 4, the sensor element 11b can expand the area of the photoelectric conversion unit 22b as the three sides of the element separation structure 23b expand. As a result, the sensitivity of the photoelectric conversion unit 22b can be improved.

FIG. 6 is a diagram showing a configuration example of the sensor element 11c of the third variation.

FIG. 6A shows a planar configuration example in the shallow portion of the sensor element 11c, and FIG. 6B shows a planar configuration example in the deep portion of the sensor element 11c. Further, C in FIG. 6 shows a cross-sectional configuration example of the sensor element 11c in the alternate long and short dash line AA shown in A and B in FIG. 6, and the surface facing downward in C in FIG. 6 is a semiconductor. It is the back surface (light incident surface) of the substrate 21. In the sensor element 11c shown in FIG. 6, the same reference numerals are given to the configurations common to the sensor element 11a in FIG. 4, and detailed description thereof will be omitted.

Similar to the sensor element 11a of FIG. 4, the sensor element 11c is provided with an element separation structure 23c so as to surround the photoelectric conversion portion 22c of the semiconductor substrate 21, and an opening 26 is provided in a part of one side of the element separation structure 23c. Is formed. Further, in the sensor element 11c, the electric charge is transferred to the FD unit 25-1 via the transfer gate 24-1 and the electric charge is transferred to the FD unit 25-2 via the transfer gate 24-2. The transfer path is configured to pass through the opening 26 of the element separation structure 23c, which is the same configuration as the sensor element 11a of FIG.

Further, in the sensor element 11c, similarly to the sensor element 11b in FIG. 5, the element separation structure 23c is other than one side provided with the transfer gates 24-1 and 24-2 and the FD portions 25-1 and 25-2. Is provided so as to be arranged at a position where the three sides of the sensor element 11c are the outer periphery of the sensor element 11c.

Here, as shown in FIG. 7, the sensor element 11c has a three-layer laminated structure in which the transistor-forming substrate 41 is laminated on the semiconductor substrate 21 and the circuit board 42 is laminated on the transistor-forming substrate 41. Then, in the sensor element 11c, the transistor forming regions 27-1 to 27-3 (not shown) are provided on the transistor forming substrate 41. That is, the sensor element 11c has a configuration in which the transistor forming regions 27-1 to 27-3 are not provided on the surface of the semiconductor substrate 21.

Similar to the sensor element 11a of FIG. 4, the sensor element 11c having such a configuration is better by suppressing the leakage of light to the FD units 25-1 and 25-2 and improving the PLS. The sensing result can be obtained.

Further, as compared with the sensor element 11a of FIG. 4, the sensor element 11c has a configuration in which the transistor forming regions 27-1 to 27-3 are not provided on the surface of the semiconductor substrate 21, so that the photoelectric conversion unit 22b The area can be expanded, and as a result, the sensitivity of the photoelectric conversion unit 22b can be improved. That is, the sensor element 11c gains a saturated charge amount by maximizing the sensitivity of the photoelectric conversion unit 22b as the light-shielding area due to the element separation structure 23c is minimized and securing the area of the photoelectric conversion unit 22c. Therefore, both the sensitivity and the saturated charge amount can be improved.

FIG. 8 is a diagram showing a configuration example of the sensor element 11d of the fourth variation.

FIG. 8A shows a planar configuration example in the shallow portion of the sensor element 11d, and FIG. 8B shows a planar configuration example in the deep portion of the sensor element 11d. Further, C in FIG. 8 shows a cross-sectional configuration example of the sensor element 11d in the alternate long and short dash line AA shown in FIGS. 8A and B, and the surface facing downward in C in FIG. 8 is a semiconductor. It is the back surface (light incident surface) of the substrate 21. In the sensor element 11d shown in FIG. 8, the same reference numerals are given to the configurations common to the sensor element 11a in FIG. 4, and detailed description thereof will be omitted.

Similar to the sensor element 11a in FIG. 4, the sensor element 11d is provided with an element separation structure 23d so as to surround the photoelectric conversion unit 22d of the semiconductor substrate 21, and an opening 26 is provided in a part of one side of the element separation structure 23d. Is formed. Further, in the sensor element 11d, the electric charge is transferred (discharged) to the drain region 51 via the transfer path and the transfer gate 24-2 through which the electric charge is transferred to the FD unit 25-1 via the transfer gate 24-1. The transfer path is configured to pass through the opening 26 of the element separation structure 23d, which is common to the sensor element 11a of FIG.

That is, the sensor element 11d has a configuration different from that of the sensor element 11a of FIG. 4 in that a drain region 51 is provided in place of the FD portion 25-2 (FIG. 4), and is otherwise shown in FIG. It has the same configuration as the sensor element 11a of No. 4.

Similar to the sensor element 11a of FIG. 4, the sensor element 11d having such a configuration can obtain better sensing results by suppressing the leakage of light to the FD unit 25 and improving the PLS. can.

Further, the sensor element 11d is preferably applied to, for example, a global shutter structure of a type in which electric charges are accumulated in the FD unit 25. That is, in the sensor element 11d, the charge transferred from the photoelectric conversion unit 22d to the FD unit 25 is generated in the photoelectric conversion unit 22 by turning on the transfer gate 24-2 during the charge accumulation time until it is read from the FD unit 25. The electric charge can be discharged to the drain region 51. As a result, it is possible to suppress the inflow of electric charge from the photoelectric conversion unit 22 to the FD unit 25-1 during the charge accumulation time, and it is possible to obtain a better sensing result.

FIG. 9 is a diagram showing a configuration example of the sensor element 11e of the fifth variation.

FIG. 9A shows a planar configuration example in the shallow portion of the sensor element 11e, and FIG. 9B shows a planar configuration example in the deep portion of the sensor element 11e. Further, C in FIG. 9 shows a cross-sectional configuration example of the sensor element 11e in the alternate long and short dash line AA shown in FIGS. 9A and B, and the surface facing downward in C in FIG. 9 is a semiconductor. It is the back surface (light incident surface) of the substrate 21. In the sensor element 11e shown in FIG. 9, the same reference numerals are given to the configurations common to the sensor element 11a in FIG. 4, and detailed description thereof will be omitted.

Similar to the sensor element 11a of FIG. 4, the sensor element 11e is provided with an element separation structure 23e so as to surround the photoelectric conversion unit 22e of the semiconductor substrate 21, and an opening 26e is provided in a part of one side of the element separation structure 23e. Is formed. Further, in the sensor element 11e, the transistor forming regions 27-1 to 27-3 are provided inside the element separation structure 23e.

Then, in the sensor element 11e, the element separation structure 23e is provided so as to be arranged at a position where all four sides thereof are the outer periphery of the sensor element 11e. Further, in the sensor element 11e, the transfer gates 24e-1 and 24e-2 are arranged inside the element separation structure 23e, and the FD portion 25e-1 and the FD portion 25e-1 and directly below the opening 26e formed in the element separation structure 23e. 25e-2 is arranged. In the sensor element 11e, the opening area 26e has a larger opening area than, for example, the opening 26a in FIG. 4 as the FD portions 25e-1 and 25e-2 are arranged directly below. Nevertheless, as shown in FIG. 9, the opening 26e is formed by making the digging depth shallow only for a part of one side of the element separation structure 23e, so that the opening 26a in FIG. 4a is formed. Is similar to.

Similar to the sensor element 11a of FIG. 4, the sensor element 11e having such a configuration is better by suppressing the leakage of light to the FD portions 25-1e and 25e-2 and improving the PLS. The sensing result can be obtained.

Further, the sensor element 11e can narrow the opening area of the opening 26e as compared with, for example, a shape in which the digging depth over all one side of the element separation structure is shallow. As a result, the sensor element 11e can improve the PLS in the near-infrared light, for example, and can suppress the near-infrared light from leaking to the FD units 25-1e and 25e-2.

FIG. 10 is a diagram showing a configuration example of the sensor element 11f of the sixth variation.

FIG. 10 shows a planar configuration example in the shallow portion of the sensor element 11f. In the sensor element 11f shown in FIG. 10, the same reference numerals are given to the configurations common to the sensor element 11a in FIG. 4, and detailed description thereof will be omitted.

Similar to the sensor element 11a of FIG. 4, the sensor element 11f is provided with an element separation structure 23 so as to surround the photoelectric conversion unit 22 of the semiconductor substrate 21, and an opening 26 is provided in a part of one side of the element separation structure 23. Is formed. Further, the sensor element 11f has a transfer path in which the charge is transferred to the FD unit 25f-1 via the transfer gate 24f-1, and the charge is transferred to the FD unit 25f-2 via the transfer gate 24f-2. The transfer path is configured to pass through the opening 26 of the element separation structure 23, which is the same configuration as the sensor element 11a of FIG. Further, in the sensor element 11f, the transistor forming regions 27-1 to 27-3 are provided outside the element separation structure 23.

Then, in the sensor element 11f, the memory area 52-1 and the read gate 53-1 are arranged between the transfer gate 24f-1 and the FD unit 25f-1, and the transfer gate 24f-2 to the FD unit 25f-2. A memory area 52-2 and a read gate 53-2 are arranged between the two. That is, the electric charge transferred from the photoelectric conversion unit 22 via the transfer gate 24f-1 is held in the memory area 52-1 and then read by the read gate 53-1 and supplied to the FD unit 25f-1. .. Similarly, the charge transferred from the photoelectric conversion unit 22 via the transfer gate 24f-2 is held in the memory area 52-2, then read by the read gate 53-2 and supplied to the FD unit 25f-2. NS.

Similar to the sensor element 11a of FIG. 4, the sensor element 11f having such a configuration is better by suppressing the leakage of light to the FD units 25-1 and 25-2 and improving the PLS. The sensing result can be obtained.

Further, the sensor element 11f is preferably applied to, for example, a global shutter structure of a type that accumulates electric charges in the memory areas 52-1 and 52-2, and the memory areas 52-1 and 52-2 are also of the PLS. It can be improved.

FIG. 11 is a diagram showing a configuration example of the sensor element 11g of the seventh variation.

FIG. 11A shows a planar configuration example in a shallow portion of the sensor element 11g, and FIG. 11B shows a schematic cross-sectional configuration example of the sensor element 11g. In the sensor element 11g shown in FIG. 11, the same reference numerals are given to the configurations common to the sensor element 11a in FIG. 4, and detailed description thereof will be omitted.

Similar to the sensor element 11a of FIG. 4, the sensor element 11g is provided with an element separation structure 23 so as to surround the photoelectric conversion portion 22 of the semiconductor substrate 21, and an opening 26 is provided in a part of one side of the element separation structure 23. Is formed. Further, in the sensor element 11g, the electric charge is transferred to the FD unit 25-1 via the transfer gate 24-1 and the electric charge is transferred to the FD unit 25-2 via the transfer gate 24-2. The transfer path is configured to pass through the opening 26 of the element separation structure 23, which is the same configuration as the sensor element 11a of FIG. Further, in the sensor element 11g, the transistor forming regions 27-1 to 27-3 are provided outside the element separation structure 23.

Here, as shown in FIG. 11B, the sensor element 11g is provided with a photoelectric conversion film 61 that absorbs visible light between the semiconductor substrate 21 and the on-chip lens 29. Therefore, in the sensor element 11g, visible light is photoelectrically converted in the photoelectric conversion film 61, and near-infrared light is photoelectrically converted in the photoelectric conversion unit 22 of the semiconductor substrate 21.

As described above, the sensor element 11g has a structure in which the photoelectric conversion film 61 is laminated and combined on the light incident surface of the semiconductor substrate 21, so that the light incident on the sensor element 11g collects the light before reaching the semiconductor substrate 21. As a result, it is possible to suppress a decrease in sensitivity of the inter-element light-shielding film 28 (see FIG. 3).

Then, the sensor element 11g, like the sensor element 11a in FIG. 4, suppresses the leakage of light to the FD units 25-1 and 25-2, and improves the PLS to obtain better sensing results. Obtainable.

FIG. 12 is a diagram showing a configuration example of the sensor element 11h, which is the eighth variation.

FIG. 12 shows a planar configuration example in the shallow portion of the sensor element 11h. In the sensor element 11h shown in FIG. 12, the same reference numerals are given to the configurations common to the sensor element 11a in FIG. 4, and detailed description thereof will be omitted.

Similar to the sensor element 11a in FIG. 4, the sensor element 11h is provided with an element separation structure 23h so as to surround the photoelectric conversion unit 22 of the semiconductor substrate 21, and openings 26-are provided at two locations in the element separation structure 23h. 1 and 26-2 are formed. Further, in the sensor element 11h, the transistor forming regions 27-1 and 27-2 are provided inside the element separation structure 23h.

In the sensor element 11h, four transfer gates 24-1 to 24-4, three FD portions 25-1 to 25-3, and a drain region 51 are provided on the surface side of the semiconductor substrate 21. That is, in the sensor element 11h, the electric charge is transferred to the FD unit 25-1 via the transfer gate 24-1 and the electric charge is transferred to the FD unit 25-2 via the transfer gate 24-2. The transfer path is configured to pass through the opening 26-1 of the element separation structure 23h. Further, in the sensor element 11h, the electric charge is transferred (discharged) to the drain region 51 via the transfer path and the transfer gate 24-4 through which the electric charge is transferred to the FD unit 25-3 via the transfer gate 24-3. The transfer path is configured to pass through the opening 26-2 of the element separation structure 23h.

Similar to the sensor element 11a of FIG. 4, the sensor element 11h having such a configuration is better by suppressing the leakage of light to the FD units 25-1 to 25-3 and improving the PLS. The sensing result can be obtained.

Further, the sensor element 11h has a transfer gate 24 in the charge accumulation time until the charge transferred from the photoelectric conversion unit 22 to the FD units 25-1 to 25-3 is read from the FD units 25-1 to 25-3. When -4 is turned on, the electric charge generated in the photoelectric conversion unit 22 can be discharged to the drain region 51. As a result, it is possible to suppress the inflow of electric charge from the photoelectric conversion unit 22 to the FD units 25-1 to 25-3 during the charge accumulation time, and it is possible to obtain a better sensing result.

In the configuration example shown in FIG. 12, openings 26 are provided at two locations, but the openings 26 may be provided at two or more locations depending on the charge transfer path.

<Sensor device configuration example>
The sensor element 11 described above is required to have further improved PLS, such as a back-illuminated indirect TOF sensor, an IR (Infrared) sensor that detects near-infrared light, and various sensors having a global shutter structure. It can be applied to sensor devices. In the indirect TOF, the distance is measured by measuring the phase shift of the modulated light.

FIG. 13 is a block diagram showing a configuration example of a sensor device to which the sensor element 11 is applied.

As shown in FIG. 13, the sensor device 101 includes an optical system 102, a sensor chip 103, a signal processing circuit 104, a monitor 105, and a memory 106, and is a still image in which the output of the sensor element 11 is used as a pixel value. It is possible to acquire a moving image.

The optical system 102 is configured to have one or a plurality of lenses, guides image light (incident light) from a subject to the sensor chip 103, and forms an image on the light incident surface of the sensor chip 103.

In the sensor chip 103, for example, a plurality of sensor elements 11 are arranged in an array, and the sensor chip 103 responds to the charge photoelectrically converted by the photoelectric conversion unit 22 according to the image formed on the light incident surface via the optical system 102. The pixel signal is supplied to the signal processing circuit 104.

The signal processing circuit 104 performs various signal processing on the pixel signal output from the sensor chip 103. The sensor image (image data) obtained by the signal processing circuit 104 performing signal processing is supplied to the monitor 105 for display, or supplied to the memory 106 for storage (recording).

In the sensor device 101 configured in this way, by applying the sensor element 11 described above, for example, an improved and accurate sensor image of PLS can be acquired.

<Example of using image sensor>
FIG. 14 is a diagram showing a usage example in which the above-mentioned sensor device 101 is used as an image sensor.

The image sensor described above can be used in various cases for sensing light such as visible light, infrared light, ultraviolet light, and X-ray, as described below.

・ Devices that take images for viewing, such as digital cameras and portable devices with camera functions. ・ For safe driving such as automatic stop and recognition of the driver's condition, in front of the car Devices used for traffic, such as in-vehicle sensors that photograph the rear, surroundings, and interior of vehicles, surveillance cameras that monitor traveling vehicles and roads, and distance measurement sensors that measure distance between vehicles, etc. Equipment used in home appliances such as TVs, refrigerators, and air conditioners to take pictures and operate the equipment according to the gestures ・ Endoscopes, devices that perform angiography by receiving infrared light, etc. Equipment used for medical and healthcare ・ Equipment used for security such as surveillance cameras for crime prevention and cameras for person authentication ・ Skin measuring instruments for taking pictures of the skin and taking pictures of the scalp Equipment used for beauty such as microscopes ・ Equipment used for sports such as action cameras and wearable cameras for sports applications ・ Camera etc. for monitoring the condition of fields and crops , Equipment used for agriculture

<Example of configuration combination>
The present technology can also have the following configurations.
(1)
A photoelectric conversion unit that receives light incident on a semiconductor substrate and performs photoelectric conversion,
A separation unit that optically separates the photoelectric conversion unit by surrounding the semiconductor substrate with a trench structure in which the semiconductor substrate is dug from the first surface side on which the light is incident.
A transfer unit provided on the second surface side of the semiconductor substrate, which is opposite to the first surface, and for transferring charges accumulated in the photoelectric conversion unit, and a transfer unit.
A charge storage unit that temporarily stores the electric charge transferred from the photoelectric conversion unit via the transfer unit, and a charge storage unit.
A sensor element including an opening provided by opening a part of one side of the separation portion, which is a charge transfer path from the photoelectric conversion unit to the charge storage unit.
(2)
The separated portion is formed in a rectangular shape in a plan view.
The three sides other than the one side on which the transfer part and the charge storage part are arranged, and the part other than the part where the opening is provided on the one side are dug to a depth penetrating the semiconductor substrate. A trench structure is formed at the depth of charge,
The sensor element according to (1) above, wherein a trench structure is formed with a shallow digging depth only at the opening.
(3)
The sensor element according to (2) above, wherein the line width of the mask pattern used when digging the trench structure to be the separation portion is formed finely in the region corresponding to the opening.
(4)
The sensor element according to any one of (1) to (3) above, wherein a predetermined number of each of the transfer unit and the charge storage unit is provided.
(5)
The separation portion is formed in a rectangular shape in a plan view, and is arranged at a position where three sides other than the one side on which the transfer portion and the charge storage portion are arranged are the outer periphery of the sensor element. The sensor element according to any one of 1) to (4).
(6)
It has a laminated structure in which at least a transistor-forming substrate is laminated on the semiconductor substrate.
The sensor element according to any one of (1) to (5) above, wherein a transistor required for driving the sensor element is provided on the transistor forming substrate.
(7)
6. Sensor element.
(8)
The separation portion is formed in a rectangular shape in a plan view, and its four sides are arranged at positions that serve as the outer circumference of the sensor element.
The sensor element according to any one of (1) to (7) above, further comprising the charge storage portion arranged directly below the opening provided in the separation portion.
(9)
A memory area and a charge reading unit are provided between the transfer unit and the charge storage unit.
The memory area holds the electric charge transferred from the photoelectric conversion unit via the transfer unit.
The sensor element according to any one of (1) to (8) above, wherein the charge reading unit reads out the charge held in the memory area and supplies the charge to the charge storage unit.
(10)
The sensor element according to any one of (1) to (9) above, further comprising a photoelectric conversion film that is laminated on the light incident surface of the semiconductor substrate and absorbs visible light.
(11)
The sensor element according to any one of (1) to (10) above, wherein the openings are provided at a plurality of locations of the separation portion.
(12)
The sensor element according to any one of (1) to (11) above, wherein the opening is provided in a curved and convex shape at the center where the opening gradually becomes shallower from both sides and becomes deepest.
(13)
The sensor element according to any one of (1) to (12) above, which is used in an application of an indirect TOF (Time of Flight) sensor that measures a distance by measuring a phase shift of modulated light.
(14)
The sensor element according to any one of (1) to (12) above, which is used in the application of an IR (Infrared) sensor that detects near-infrared light by the photoelectric conversion unit.
(15)
A photoelectric conversion unit that receives light emitted from a semiconductor substrate and performs photoelectric conversion,
A separation unit that optically separates the photoelectric conversion unit by surrounding the semiconductor substrate with a trench structure in which the semiconductor substrate is dug from the first surface side irradiated with light.
A transfer unit provided on the second surface side of the semiconductor substrate, which is opposite to the first surface, and for transferring charges accumulated in the photoelectric conversion unit, and a transfer unit.
A charge storage unit that temporarily stores the electric charge transferred from the photoelectric conversion unit via the transfer unit, and a charge storage unit.
A sensor device including a sensor element having an opening provided by opening a part of one side of the separation portion, which is a charge transfer path from the photoelectric conversion unit to the charge storage unit.

The present embodiment is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present disclosure. Further, the effects described in the present specification are merely examples and are not limited, and other effects may be obtained.

11 Sensor element, 21 Semiconductor substrate, 22 Photoelectric conversion part, 23 Element separation structure, 24 Transfer gate, 25 FD part, 26 Aperture, 27 Transistor formation area, 28 Inter-element shading film, 29 On-chip lens, 31 Aperture area, 32 Narrow area, 41 Transistor forming board, 42 Circuit board, 51 Drain area, 52 Memory area, 53 Read gate, 61 Photoelectric conversion film

Claims (15)

A photoelectric conversion unit that receives light incident on a semiconductor substrate and performs photoelectric conversion,
A separation unit that optically separates the photoelectric conversion unit by surrounding the semiconductor substrate with a trench structure in which the semiconductor substrate is dug from the first surface side on which the light is incident.
A transfer unit provided on the second surface side of the semiconductor substrate, which is opposite to the first surface, and for transferring charges accumulated in the photoelectric conversion unit, and a transfer unit.
A charge storage unit that temporarily stores the electric charge transferred from the photoelectric conversion unit via the transfer unit, and a charge storage unit.
A sensor element including an opening provided by opening a part of one side of the separation portion, which is a charge transfer path from the photoelectric conversion unit to the charge storage unit. The separated portion is formed in a rectangular shape in a plan view.
The three sides other than the one side on which the transfer part and the charge storage part are arranged, and the part other than the part where the opening is provided on the one side are dug to a depth penetrating the semiconductor substrate. A trench structure is formed at the depth of charge,
The sensor element according to claim 1, wherein a trench structure is formed with a shallow digging depth only at the opening. The sensor element according to claim 2, wherein the line width of the mask pattern used when digging the trench structure to be the separation portion is formed finely in a region corresponding to the opening. The sensor element according to claim 1, wherein a predetermined number of each of the transfer unit and the charge storage unit is provided. The separation portion is formed in a rectangular shape in a plan view, and is arranged at a position where three sides other than the one side on which the transfer portion and the charge storage portion are arranged are the outer periphery of the sensor element. The sensor element according to 1. It has a laminated structure in which at least a transistor-forming substrate is laminated on the semiconductor substrate.
The sensor element according to claim 1, wherein a transistor required for driving the sensor element is provided on the transistor forming substrate. The sensor element according to claim 1, further comprising a charge discharging unit that discharges the charge generated by the photoelectric conversion unit during the charge storage time in which the charge is temporarily accumulated in the charge storage unit. The separation portion is formed in a rectangular shape in a plan view, and its four sides are arranged at positions that serve as the outer circumference of the sensor element.
The sensor element according to claim 1, further comprising the charge storage portion arranged directly below the opening provided in the separation portion. A memory area and a charge reading unit are provided between the transfer unit and the charge storage unit.
The memory area holds the electric charge transferred from the photoelectric conversion unit via the transfer unit.
The sensor element according to claim 1, wherein the charge reading unit reads out the charge held in the memory area and supplies the charge to the charge storage unit. The sensor element according to claim 1, further comprising a photoelectric conversion film that is laminated on the light incident surface of the semiconductor substrate and absorbs visible light. The sensor element according to claim 1, wherein the openings are provided at a plurality of locations of the separation portion. The sensor element according to claim 1, wherein the opening is provided in a curved and convex shape at the center where the opening gradually becomes shallower from both sides and becomes deepest. The sensor element according to claim 1, which is used in an application of an indirect TOF (Time of Flight) sensor that measures a distance by measuring a phase shift of modulated light. The sensor element according to claim 1, which is used in an application of an IR (Infrared) sensor that detects near-infrared light by the photoelectric conversion unit. A photoelectric conversion unit that receives light emitted from a semiconductor substrate and performs photoelectric conversion,
A separation unit that optically separates the photoelectric conversion unit by surrounding the semiconductor substrate with a trench structure in which the semiconductor substrate is dug from the first surface side irradiated with light.
A transfer unit provided on the second surface side of the semiconductor substrate, which is opposite to the first surface, and for transferring charges accumulated in the photoelectric conversion unit, and a transfer unit.
A charge storage unit that temporarily stores the electric charge transferred from the photoelectric conversion unit via the transfer unit, and a charge storage unit.
A sensor device including a sensor element having an opening provided by opening a part of one side of the separation portion, which is a charge transfer path from the photoelectric conversion unit to the charge storage unit.

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