JP2018061060A - Solid-state imaging apparatus and imaging system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of noise.SOLUTION: A solid-state imaging apparatus includes a plurality of pixels each including: a photoelectric conversion part which applies photoelectric conversion to incident light to generate a signal charge; a charge storage part which stores the signal charge transferred from the photoelectric conversion part; a floating diffusion part to which the signal charge in the charge storage part is transferred; a waveguide for converging the incident light to the photoelectric conversion part; and a light shielding part which is provided to cover at least the charge storage part and includes an opening for making the converged light incident to the photoelectric conversion part. The waveguide includes an incident part to which light is made incident and an emission part which emits light, and an interval between the emission part and the photoelectric conversion part is larger than an interval between a lower end of the light shielding part and the photoelectric conversion part.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a solid-state imaging device and an imaging system using the same.

  Patent Document 1 discloses a solid-state imaging device in which pixels including a photoelectric conversion unit, an optical waveguide, and a charge storage unit to which charges are transferred from the photoelectric conversion unit are arranged. The optical waveguide is provided for condensing light to the photoelectric conversion unit. The area other than the photoelectric conversion part is covered with a light shielding film. Patent Document 1 describes that an in-plane synchronous electronic shutter is realized by simultaneously starting and ending transfer of charges from the photoelectric conversion unit to the charge storage unit for all the pixels. ing.

JP2011-238949A

When light is incident on the charge storage unit, charges are generated in the charge storage unit, which may cause noise. Patent Document 1 does not specifically disclose the positional relationship between the optical waveguide and the light shielding portion. Depending on the positional relationship between the optical waveguide and the light shielding portion, incident light may be incident on the charge storage portion and noise may be generated.
The present invention has been made in view of the above-described problems, and an object thereof is to suppress the generation of noise.

  A solid-state imaging device according to one embodiment of the present invention includes a semiconductor substrate, a photoelectric conversion unit that is disposed on the semiconductor substrate and photoelectrically converts incident light to generate a signal charge, and a signal charge transferred from the photoelectric conversion unit A plurality of pixels including: a charge storage unit that stores charge; a transistor having a control electrode for transferring charge from the photoelectric conversion unit to the charge storage unit; and a floating diffusion unit to which signal charges of the charge storage unit are transferred , A waveguide for guiding the incident light to the photoelectric conversion portion, and a light shielding portion provided so as to cover at least the charge storage portion, the light shielding portion including a first portion covering the control electrode, and a semiconductor A second portion disposed on the substrate via an insulating layer and extending along the surface of the semiconductor substrate so as to cover a portion of the photoelectric conversion portion, and between the waveguide and the semiconductor substrate An insulating layer is arranged, and the waveguide and Distance between conductors substrate is greater than the distance between the second portion and the semiconductor substrate of the light-shielding portion, and wherein the less than the distance between the upper surface and the semiconductor substrate of the second portion of the light-shielding portion.

  According to the solid-state imaging device of the present invention, the generation of noise can be suppressed.

It is a figure which shows the circuit structure of the pixel which concerns on 1st Embodiment. It is the top view (a) and sectional drawing (b) of the pixel which concern on 1st Embodiment. It is a figure explaining the positional relationship of the light shielding film and waveguide concerning 1st Embodiment. It is a figure explaining the modification of the positional relationship of the light shielding film and waveguide which concern on 1st Embodiment. It is a figure explaining the positional relationship of the light shielding film and waveguide concerning 2nd Embodiment. It is a figure explaining the positional relationship of the light shielding film and waveguide concerning 3rd Embodiment. It is the top view (a) and sectional drawing (b) of the pixel which concern on 4th Embodiment. It is a top view of the pixel concerning a 5th embodiment. It is sectional drawing of the pixel which concerns on 5th Embodiment. It is a block diagram of the imaging system concerning a 6th embodiment.

  Hereinafter, embodiments of a solid-state imaging device according to the present invention will be described in detail. Throughout the drawings, the same components are denoted by the same reference numerals, and the description of the overlapping components may be omitted. In addition, the embodiment described below is an example of one aspect of the present invention, and the present invention is not limited to the following embodiment.

(First embodiment)
FIG. 1 is a diagram showing a circuit configuration of a pixel according to the first embodiment of the present invention. A pixel is an element that converts incident light into an electrical signal and outputs the electrical signal. A pixel array which is a light receiving unit of the solid-state imaging device is configured by arranging the pixels in a matrix. The pixel is formed on a semiconductor substrate such as silicon (Si).

  The pixel includes a photoelectric conversion unit 1, a charge storage unit 2, a floating diffusion unit (FD unit) 3, a vertical output line 8, and an overflow drain unit (OFD unit) 15. The pixel includes a first transfer transistor 4, a second transfer transistor 5, a selection transistor 7, a reset transistor 9, a source follower transistor 10, and an OFD transistor 16 for switching connection / disconnection of these parts or signal amplification. Further prepare. Each transistor is composed of a MOSFET or the like, and has a gate electrode provided as a control electrode between the drain and the source.

  The photoelectric conversion unit 1 is an element that generates signal charges according to the amount of incident light. The charge storage unit 2 is connected to the photoelectric conversion unit 1 via the first transfer transistor 4. The charge storage unit 2 functions as a grounded capacitor in terms of circuit, and the charge storage unit 2 temporarily stores the charge transferred from the photoelectric conversion unit 1.

  The FD unit 3 converts the charge transferred from the charge storage unit 2 into a voltage signal. The FD unit 3 is connected to the charge storage unit 2 through the second transfer transistor 5. The FD unit 3 is also connected to the source terminal of the reset transistor 9 and the gate terminal of the source follower transistor 10. A power supply voltage is supplied to the drain terminal of the reset transistor 9. By turning on the reset transistor 9, the voltage of the FD section 3 is reset to the power supply voltage. At this time, the reset signal voltage is output to the source terminal of the source follower transistor 10.

  When the transfer transistor 5 is turned on and charges are transferred from the charge storage unit 2 to the FD unit 3, a pixel signal voltage corresponding to the transferred charge amount is output to the source terminal of the source follower transistor 10.

  The source terminal of the source follower transistor 10 is connected to the drain terminal of the selection transistor 7. The source terminal of the selection transistor 7 is connected to the vertical output line 8. When the selection transistor 7 is turned on, a reset signal or a pixel signal is output to the vertical output line 8. In this way, the signal is read from the pixel.

  An OFD unit 15 is further connected to the photoelectric conversion unit 1 via an OFD transistor 16. When the OFD transistor 16 is turned on, the charge accumulated in the photoelectric conversion unit 1 is discharged to the OFD unit 15. By discharging the charges to all the pixels simultaneously to the OFD unit 15 and then transferring the accumulated charges to the charge storage unit 2, an electronic shutter that simultaneously sets a constant exposure time for all the pixels is realized. As a result, a shift in exposure timing that occurs in order to sequentially read out charges from each pixel is suppressed, and image distortion is reduced.

  2A is a plan view of a pixel according to the first embodiment of the present invention, and FIG. 2B is a cross-sectional view taken along line X-X ′ of FIG. Portions corresponding to those in the circuit of FIG. 1 are denoted by the same reference numerals, and description of the configuration and functions already described may be omitted.

  The pixel further includes a color filter 100, a microlens 101, an in-layer lens 102, and a waveguide 31 as an optical system disposed immediately above the photoelectric conversion unit 1. The photoelectric conversion unit 1 is an embedded photodiode. Light incident from above the photoelectric conversion unit 1 sequentially passes through the microlens 101, the color filter 100, the in-layer lens 102, and the waveguide 31, enters the photoelectric conversion unit 1, and is converted into electrons. In addition, although each member, such as the intralayer lens 102, the waveguide 31, the wiring 41, 42, 43, and the photoelectric conversion portion 1, is illustrated as a gap in the drawing, an interlayer insulating layer ( (Not shown) is formed.

  The microlens 101 and the in-layer lens 102 are lenses for improving sensitivity by concentrating incident light on the photoelectric conversion unit 1. The color filter 100 is a thin film that selectively transmits light of a specific wavelength, and is provided to obtain an image signal including color information.

  The waveguide 31 is opposed to the inner lens 102 side, and has an upper opening (incident part) where light is incident, and a lower opening (emitter) opposite to the photoelectric conversion part 1 and from which light is emitted. Have. As shown in FIG. 2A, the end 31b of the upper opening and the end 31a of the lower opening are circular. In the X-X ′ cross section shown in FIG. 2B, the waveguide 31 has a trapezoidal shape in which the width of the upper opening is wider than the width of the lower opening. In addition, although the upper surface shape of the waveguide 31 is illustrated as a circle, it may be a square, a rectangle, an ellipse, a polygon, or the like.

  The waveguide 31 has a function of concentrating incident light on the photoelectric conversion unit 1. Since the amount of light incident on the photoelectric conversion unit 1 by the waveguide 31 is increased, the sensitivity is improved as compared with the case without the waveguide 31. In particular, when the area of the photoelectric conversion unit 1 is small or the F number is large, a decrease in sensitivity may be a problem, but by providing the waveguide 31, this influence can be suppressed.

  A silicon oxide film (SiO) with a refractive index of about 1.5 is used as the material for the interlayer insulating layer between the wiring portions, and a silicon oxynitride film (SiON) with a refractive index of about 1.8 is used as the material for the waveguide 31. be able to. Light incident obliquely at a predetermined angle with respect to the interface between the waveguide 31 and the interlayer insulating layer is totally reflected at the interface. Accordingly, light does not leak into the interlayer insulating layer but propagates in the waveguide 31 and is guided to the photoelectric conversion unit 1.

  The material of the interlayer insulating layer and the waveguide 31 is not limited to a combination of a silicon oxide film and a silicon oxynitride film. Any material may be selected as long as the materials are combined so that the refractive index of the waveguide 31 is higher than the refractive index of the interlayer insulating layer. For example, the interlayer insulating layer may be a silicon oxide film, and the waveguide 31 may be a silicon nitride film (SiN) having a refractive index of about 2.0. Alternatively, an organic film material and a material in which particles such as titanium oxide are mixed in the organic film material may be used. The interlayer insulating layer may be formed of a laminated film made of different materials. In that case, if the refractive index of the waveguide 31 is configured to be higher than the volume average of the refractive indexes of the surrounding interlayer insulating layers. Good.

  The inclination angle of the side wall of the waveguide 31 can be determined by Snell's law. For example, when the refractive index of the waveguide 31 is 1.9 and the refractive index of the interlayer insulating layer is 1.46, the light incident at an incident angle of 50.2 degrees or more with respect to the perpendicular of the side wall of the waveguide 31 is all. reflect. For example, if the angle of the side wall of the waveguide 31 is set to 39.8 degrees or less with respect to the vertical direction of the substrate, leakage of the light incident perpendicularly to the waveguide 31 is suppressed and reaches the photoelectric conversion unit 1. The larger the ratio of the refractive index of the waveguide 31 to the interlayer insulating layer, the wider the range of incident angles that can be totally reflected, and the degree of freedom in designing the side wall angle is improved.

  An antireflection layer may be provided in the optical path of incident light such as between the upper opening of the waveguide 31 and the intralayer lens 102 and between the lower opening and the photoelectric conversion unit 1. Since the loss of light quantity due to reflection is reduced and the transmittance of incident light is improved, the sensitivity can be improved.

  The pixel further includes wirings 41, 42, and 43 for signal transmission and the like. Since the wirings 41, 42, and 43 are formed of a material such as aluminum or copper that does not easily transmit light, the wirings 41, 42, and 43 are arranged around the waveguide 31 so as to avoid the waveguide 31.

  Next, the structure of the photoelectric conversion unit 1 and the charge storage unit 2 will be described. The photoelectric conversion unit 1 includes a first conductivity type first semiconductor region 11 and a second conductivity type second semiconductor region 12. The second semiconductor region 12 is formed on the substrate surface, and the first semiconductor region 11 is disposed immediately below. Hereinafter, the first conductivity type will be described as n-type, and the second conductivity type will be described as p-type. The junction interface between the first semiconductor region 11 and the second semiconductor region 12 forms a PN junction. That is, the photoelectric conversion unit 1 has a buried structure in which the PN junction interface is inside the substrate and does not contact the substrate surface. In the embedded structure, the influence of noise on the substrate surface is suppressed because the PN junction interface is embedded in the substrate.

  An n-type third semiconductor region 13 is further formed immediately below the first semiconductor region 11. The impurity concentration of the third semiconductor region 13 is lower than the impurity concentration of the first semiconductor region 11. Thereby, electrons photoelectrically converted in the third semiconductor region 13 can be collected in the first semiconductor region 11. Note that the third semiconductor region 13 may be p-type.

  A fourth semiconductor region 17 is formed below the third semiconductor region 13, and the fourth semiconductor region 17 extends to the regions of the charge storage portion 2 and the FD portion 3. The fourth semiconductor region 17 is a p-type semiconductor region. The fourth semiconductor region 17 functions as a potential barrier against electrons generated in the photoelectric conversion unit 1 and has a function of suppressing leakage of electrons to the substrate.

  The charge storage unit 2 includes an n-type fifth semiconductor region 201 and a p-type sixth semiconductor region 202. The sixth semiconductor region 202 is formed on the surface of the substrate, and the fifth semiconductor region 201 is disposed immediately below. Similarly to the photoelectric conversion unit 1, the charge storage unit 2 has a buried structure and can suppress noise on the substrate surface. Note that the sixth semiconductor region 202 may be omitted, and only the fifth semiconductor region 201 may be disposed to form the charge storage unit 2. In that case, the gate electrode of the first transfer transistor 4 is extended so as to cover the charge storage section 2, and a negative potential is applied to the electrode to induce holes on the surface, thereby suppressing noise generated at the interface. can do.

  The pixel further includes a light-shielding film 203 as a light-shielding part that covers other than just above the photoelectric conversion part 1. The light shielding film 203 is disposed so as to cover at least the charge accumulation unit 2 and the gate electrode of the first transfer transistor 4. Since the portions other than the photoelectric conversion portion are shielded from light and the photoelectric conversion portion 1 needs to be irradiated with light, an opening is provided immediately above the photoelectric conversion portion 1 of the light shielding film 203. However, the light shielding film 203 may partially extend at the end of the photoelectric conversion unit 1.

  The light shielding film 203 suppresses the incidence of light on the charge storage unit 2 and the like. Thereby, it is suppressed that an electric charge is produced | generated in the charge storage part 2 by incident light, and noise generate | occur | produces. The light shielding film 203 can be formed using a material that hardly transmits visible light, such as tungsten, tungsten silicide, tungsten oxide film, aluminum, or an alloy film thereof. The thickness of the light shielding film 203 is, for example, about 100 to 200 nm. Since the light shielding film 203 is formed in a lump in a portion where the gate electrode is disposed and a portion where the gate electrode is not disposed, the light shielding film 203 has unevenness due to the film thickness of the gate electrode.

  FIG. 3 is a view for explaining the positional relationship between the light shielding film 203 and the waveguide 31 in the present embodiment. 3 is a cross-sectional view taken along the line XX ″ of FIG. 2A, and is an enlarged view of the vicinity of the photoelectric conversion unit 1 of FIG.

  Dotted lines indicated by reference numerals h2031, h2032, h2033, and h311 in FIG. 3 indicate intervals (heights) between the light shielding film 203 and the waveguide 31 and the photoelectric conversion unit 1 that is the substrate surface. For example, the dotted line to which the symbol h311 is attached means that the position of the bottom portion (outgoing portion) of the waveguide 31 is the height h311. In the following description, this symbol may be used to express “the height of the bottom of the waveguide 31 is h311” or the like.

  The height of the lower end of the light shielding film 203 is h2031, the height of the upper end of the light shielding film in the region without the gate electrode is h2032, and the height of the upper end of the light shielding film in the region where the light shielding film 203 is formed on the gate electrode is h2033. . The height h311 of the bottom of the waveguide 31 is preferably higher than the height h2031 of the lower end of the light shielding film 203. In the present embodiment, the height h311 of the bottom of the waveguide 31 is between the height h2032 and the height h2033.

  When the height h311 of the bottom of the waveguide is lower than the height h2031 of the lower end of the light shielding film 203, the light emitted from the bottom of the waveguide 31 spreads by diffraction, and not only in the photoelectric conversion unit 1 but also in the charge storage unit 2. Is also incident. When light enters the charge storage unit 2, charges are generated at the PN junction of the charge storage unit 2, and this charge can cause noise. On the other hand, in the present embodiment, the height h311 of the bottom of the waveguide is higher than the height h2031 of the lower end of the light shielding film 203. Therefore, even if the light emitted from the bottom of the waveguide 31 spreads by diffraction, it is blocked by the light shielding film 203. Thereby, since it can reduce or prevent that light enters into the electric charge storage part 2, generation | occurrence | production of noise can be suppressed.

  FIGS. 4A and 4B are diagrams for explaining a modification of the positional relationship between the waveguide 31 and the light shielding film 203. 4 is also a cross-sectional view taken along the line XX ″ in FIG. 2A, and shows an enlarged view of the vicinity of the photoelectric conversion unit 1 in FIG. 2B. In FIGS. The position of the waveguide 31 is different from the configuration shown in FIG.

  In FIG. 4A, the height h311 at the bottom of the waveguide 31 is between the height h2031 at the lower end of the light shielding film 203 and the height h2032 at the upper end of the film in the region without the gate electrode. In this case, the diffracted light emitted from the bottom of the waveguide 31 is reflected by the side surface of the light shielding film 203. Therefore, it is possible to reduce or prevent the light from being incident on the charge storage portion as in the case described above, so that the generation of noise can be suppressed. The light reflected by the side surface of the light shielding film 203 can be incident on the photoelectric conversion unit 1. Since the component reflected on the upper surface of the light shielding film 203 decreases and the amount of light reflected on the side surface of the light shielding film 203 and condensed on the photoelectric conversion unit 1 increases, higher sensitivity can be obtained.

  In FIG. 4B, the height h311 of the bottom of the waveguide 31 is higher than the height h2033 of the upper end of the light shielding film in the region where the light shielding film 203 is formed on the gate electrode. The waveguide 31 is provided to allow light incident on the pixels to pass through the wirings 41, 42, 43 and the layer on which the interlayer insulating layer is formed and to collect the light in the photoelectric conversion unit 1. Therefore, the waveguide 31 may be provided so as to penetrate at least one layer in which the circuit wirings 41, 42, and 43 and the interlayer insulating layer are formed. The heights of the circuit wirings 41, 42, 43 and the upper end surface of the interlayer insulating layer on the wiring 43 are h413, h423, h433, and h443, respectively. At this time, if the height 311 of the bottom of the waveguide 31 is at least a position lower than the height h433, the above-described effects can be obtained. It is more preferable that the height h311 of the bottom portion of the waveguide 31 is lower than the height h423 of the upper end surface of the wiring. FIG. 4B shows a more preferable example in which the height h311 of the bottom of the waveguide 31 is between the height h423 of the upper end surface of the wiring 42 and the height h413 of the upper end surface of the wiring 41. ing.

(Second Embodiment)
FIG. 5 is a diagram illustrating the positional relationship between the light shielding film 203 and the waveguide 31 in the second embodiment. 5 is a cross-sectional view of a portion corresponding to XX ″ in FIG. 2A, and shows the vicinity of the photoelectric conversion unit 1 in an enlarged manner. The second embodiment is the same as that of the first embodiment. In addition to the configuration, an antireflection layer 52 is disposed between the waveguide 31 and the photoelectric conversion unit 1.

  A gate insulating film 51 is formed between the gate electrodes of the first transfer transistor 4 and the OFD transistor 16 and the substrate. For example, a silicon oxide film is used for the gate insulating film 51, and its film thickness is about 10 nm. An antireflection layer 52 is formed on the gate insulating film 51.

  For example, a silicon nitride film is used for the antireflection layer 52, and the film thickness is about 50 nm. A buffer film 53 is formed between the antireflection layer 52 and the light shielding film 203. For example, a silicon oxide film is used for the buffer film 53, and the film thickness is about 20 to 100 nm. In order to obtain an antireflection effect, the waveguide 31 and the antireflection layer 52 need to be at an appropriate distance. When the wavelength of light is 550 nm and the refractive index of the waveguide 31 is 1.8, the distance between the waveguide 31 and the antireflection layer 52 is appropriately about 110 nm. Therefore, the distance from the substrate to the bottom 311 of the waveguide 31 is about 170 nm, and the distance from the substrate to the height h2031 at the lower end of the light shielding film 203 is about 80 to 160 nm. From the relationship between these distances, the distance between the height h311 of the bottom of the waveguide 31 and the height h2031 of the lower end of the light shielding film 203 is 10 to 90 nm. That is, the height h311 of the bottom portion of the waveguide 31 can be set higher than the height h2031 of the lower end of the light shielding film 203.

  Therefore, also in this embodiment, it is possible to reduce or prevent light from entering the charge accumulating unit 2 as in the first embodiment, and thus it is possible to suppress the generation of noise. In addition to this, the effect of the antireflection layer 52 reduces the loss of light quantity due to reflection and improves the transmittance of incident light, so that the sensitivity can be improved.

(Third embodiment)
FIG. 6 is a view for explaining the positional relationship between the light shielding film 203 and the waveguide 31 in the third embodiment. FIG. 6 is a cross-sectional view of a portion corresponding to XX ″ in FIG. 2A, and shows the vicinity of the photoelectric conversion unit 1 in an enlarged manner.

  In addition to the trapezoidal shape described above, the waveguide 31 in FIG. 6 has a T shape having a portion in which the upper opening extends outward. Further, an etching stop layer (ESL) 32 for forming the waveguide 31 is provided at the bottom of the waveguide 31 in FIG. The ESL 32 is a layer for stably completing the etching process at a predetermined depth. The film thickness of ESL32 is, for example, 50 nm. When the ESL 32 has a refractive index equivalent to that of the waveguide 31, the ESL 32 has a light collecting effect similarly to the waveguide 31. The shape of this embodiment may be adopted for manufacturing reasons.

  The width of the opening at the bottom of the waveguide 31 (opening width under the waveguide) is w31a, the width of the opening at the top of the waveguide 31 (opening width on the waveguide) w31b, and the opening width of the light shielding film 203 (light shielding opening width). Is w203a. Similar to the first embodiment, the height 311 of the bottom of the waveguide 31 is higher than the height h2031 of the lower end of the light shielding film 203. The effect of this configuration is as described above in the first embodiment. In addition, in this embodiment, the light shielding opening width w203a of the light shielding film 203 is longer than the waveguide lower opening width w31a and shorter than the waveguide upper opening width w31b. At this time, the end portion 203 a of the light shielding film 203 is positioned between the bottom end portion 31 a of the waveguide 31 and the top end portion 31 b of the waveguide 31 when viewed from the optical axis direction of the waveguide 31. Hereinafter, the effect by this structure is demonstrated.

  When the light shielding opening width w203a is shorter than the waveguide lower opening width w31a, part of the light output from the bottom of the waveguide 31 is reflected by the light shielding film 203, and the light flowing into the photoelectric conversion unit 1 is reduced. Sensitivity can be reduced. On the other hand, in the present embodiment, since the light shielding opening width w203a is longer than the waveguide lower opening width w31a, the light output from the bottom of the waveguide 31 is not easily reflected by the light shielding film 203, and the sensitivity is improved. To do.

  On the other hand, when the light shielding opening width w203a is longer than the on-waveguide opening width w31b, the incident light cannot be sufficiently taken into the waveguide 31 and the sensitivity can be lowered. Further, since the light shielding opening width w203a is large, diffracted light is incident on the charge storage unit 2 and noise may be generated. On the other hand, in the present embodiment, since the light shielding opening width w203a is shorter than the waveguide upper opening width w31b, the sensitivity is improved, the inflow of light to the charge storage unit 2 is prevented, and the generation of noise is suppressed. Is done.

  The positions of the wirings 41, 42, and 43 may be outside the end 31 a at the bottom of the waveguide 31, and may be inside the end 31 b at the top of the waveguide 31. The same applies to other embodiments.

(Fourth embodiment)
FIG. 7A is a plan view of a pixel according to the fourth embodiment of the present invention, and FIG. 7B is a cross-sectional view taken along line YY ′ of FIG. Corresponding members are given the same reference numerals.

  As shown in FIGS. 7A and 7B, the difference between this embodiment and each of the above-described embodiments is that the opening of the light shielding film 203 is the source follower transistor 10, the selection transistor 7, and the reset transistor 9. It is a point that partially overlaps. Therefore, a step is generated when the ESL 32 is formed due to the step of the gate electrode of the source follower transistor 10 or the like, and the bottom of the waveguide 31 has a step.

  For the reasons described above, it is necessary to shield the charge storage unit 2 in order to prevent noise. On the other hand, light shielding to the source follower transistor 10, the selection transistor 7, and the reset transistor 9 is not always necessary.

  Also in the present embodiment, as in the third embodiment, the end 203a of the light shielding opening 203 in the direction from the photoelectric conversion unit 1 to the charge storage unit 2 is guided by the end of the waveguide lower opening width 31a. What is necessary is just to be located between the edge parts of the road opening width 31b. That is, the gate electrode of the source follower transistor 10 or the like described above may overlap with the opening of the light shielding film 203. By arranging in this way, the use efficiency of the element area can be improved while maintaining the light shielding of the charge storage section 2. Therefore, by using the shape of the waveguide 31 and the element layout of the fourth embodiment, both the reduction in size of the pixel and the suppression of noise can be achieved.

(Fifth embodiment)
A fifth embodiment will be described with reference to FIGS. In FIG. 8 and FIG. 9, the reference numerals of the parts having the same functions as those in FIGS. 2A and 2B are the same. FIG. 8 is a plan view of a pixel according to the fifth embodiment, and FIG. 9 is a cross-sectional view of the pixel according to the fifth embodiment of the present invention at ZZ ′ in FIG. The pixels according to the fifth embodiment are used as pixels arranged in the peripheral part of the pixel array of the solid-state imaging device. In the peripheral part of the pixel array, light emitted from the subject may enter the pixel obliquely. The light incident obliquely is partially blocked by the light shielding film 203, and the amount of light incident on the photoelectric conversion unit 1 may be reduced. As a result, the amount of light is insufficient at the periphery of the pixel array. When photographing is performed with a photographing system such as a camera using such a pixel array, the peripheral portion of the image may become dark due to insufficient light quantity.

  In this embodiment, in order to improve the light collection performance even for obliquely incident light, in this embodiment, the micro lens 501, the color filter 500, the in-layer lens 502, and the waveguide 531 extend from the perpendicular P passing through the center of the pixel to the imaging area of the sensor chip. It is arranged shifted in the central direction. In the figure, reference numeral 531 a denotes an opening at the bottom of the waveguide 531. As a result, as shown in FIG. 2B, the oblique incident light is blocked by the light shielding film 203 as compared with the case where the centers of the microlens 101, the inner lens 102, the waveguide 31 and the like coincide with the perpendicular line P. Loss of light due to being suppressed. Therefore, by using the pixel according to the fifth embodiment in the peripheral portion of the pixel array, it is possible to improve the light quantity shortage in the peripheral portion of the pixel array. The “center of the pixel”, which is the position of the perpendicular line P, may be defined by the center of gravity of the opening of the light shielding film, and is defined by the center of gravity of the first and second conductivity type semiconductor regions constituting the photoelectric conversion unit 1. May be.

  Note that the shift amounts of the optical members such as the microlens 501, the in-layer lens 502, and the waveguide 531 can be appropriately adjusted based on sensitivity, optical characteristics, and light shielding performance of the charge storage unit 2. For example, the vertices of the microlens 501, the intralayer lens 502, and the waveguide 531 may be set uniformly with respect to the row or column of each pixel. The shift amount may be increased depending on the distance from the center of the pixel array. In the two pixels shown in FIG. 9, the left pixel is closer to the center of the imaging area than the right pixel. In this case, as shown in FIG. 9, the shift amount S2 of the waveguide of the right pixel far from the center of the imaging area (pixel array) is the shift amount of the waveguide of the left pixel close to the center of the imaging area. It is preferable to make it larger than the amount S1.

  The optical material shifted from the center of the pixel can be appropriately selected. Only one of the microlens 501, the intralayer lens 502, the waveguide 531 and the color filter 500 may be shifted, or two or more may be shifted. In each optical member, the shift amount may be different, and it is preferable to increase the shift amount as the optical member is located farther from the photoelectric conversion unit 1.

  As a modification of the present embodiment, the direction in which the above-described optical member is displaced may be the direction in which the photoelectric conversion unit 1 and the charge storage unit 2 are arranged (the vertical direction in FIG. 8). Since the incidence of light on the charge storage unit 2 can be further reduced or prevented, the generation of noise can be further suppressed.

(Sixth embodiment)
FIG. 10 is a diagram illustrating a configuration of an imaging system using a solid-state imaging device according to the sixth embodiment of the present invention. The imaging system 800 includes an optical unit 810, a solid-state imaging device 820, a video signal processing unit 830, a recording / communication unit 840, a timing control unit 850, a system control unit 860, and a playback / display unit 870. As the solid-state imaging device 820, the solid-state imaging device described above as the first to fifth embodiments is used.

  An optical unit 810 that is an optical system such as a lens forms an image of a subject by forming light from the subject on a pixel array in which a plurality of pixels are two-dimensionally arranged in the solid-state imaging device 820. The solid-state imaging device 820 outputs a signal corresponding to the light imaged on the pixel at a timing based on the signal from the timing control unit 850. A signal output from the solid-state imaging device 820 is input to the video signal processing unit 830. The video signal processing unit 830 processes an input signal according to a method determined by a program or the like. The signal obtained by the processing in the video signal processing unit 830 is sent to the recording / communication unit 840 as image data. The recording / communication unit 840 sends a signal for forming an image to the reproduction / display unit 870 and causes the reproduction / display unit 870 to reproduce / display a moving image or a still image. The recording / communication unit 840 receives a signal from the video signal processing unit 830 and communicates with the system control unit 860, and also records an operation for recording a signal for forming an image on a recording medium (not shown). Do.

  The system control unit 860 controls the operation of the imaging system 800 in an integrated manner, and controls driving of the optical unit 810, timing control unit 850, recording / communication unit 840, and reproduction / display unit 870. The system control unit 860 includes a storage device (not shown) that is a recording medium, for example, and a program and the like necessary for controlling the operation of the imaging system 800 are recorded therein. Further, the system control unit 860 supplies a signal for switching the drive mode in the imaging system 800 according to, for example, a user operation. Specifically, a signal for switching a row to be read out or a row to be reset, a change in the angle of view associated with electronic zoom, a shift in angle of view associated with electronic image stabilization, and the like is supplied. The timing control unit 850 controls the drive timing of the solid-state imaging device 820 and the video signal processing unit 830 based on control by the system control unit 860.

  By mounting the solid-state imaging device 820 according to the present embodiment, it is possible to realize an imaging system 800 in which noise generation is suppressed.

DESCRIPTION OF SYMBOLS 1 Photoelectric conversion part 2 Charge storage part 31 Waveguide 203 Light-shielding part (light-shielding film)

A solid-state imaging device according to one embodiment of the present invention includes a semiconductor substrate, a photoelectric conversion unit that is disposed on the semiconductor substrate and photoelectrically converts incident light to generate a signal charge, and is transferred from the photoelectric conversion unit A charge storage section that stores signal charges; a transistor having a control electrode for transferring charges from the photoelectric conversion section to the charge storage section; a floating diffusion section to which the signal charges of the charge storage section are transferred; A plurality of pixels including: a waveguide for guiding incident light to the photoelectric conversion unit; a light shielding unit covering at least the control electrode and the charge storage unit; and a plurality of light emitting units disposed on the light shielding unit. A wiring layer, and the waveguide has an upper end located farther from the semiconductor substrate than at least a part of the plurality of wiring layers, and the half of the waveguide from the at least a part of the plurality of wiring layers. A lower end at a position close to a body substrate, an insulating layer is disposed between the lower end of the waveguide and the semiconductor substrate, and an interval between the lower end of the waveguide and the semiconductor substrate is The distance between the upper end of the light shielding portion and the semiconductor substrate is smaller .

Claims (17)

A semiconductor substrate;
A photoelectric conversion unit that is arranged on the semiconductor substrate and photoelectrically converts incident light to generate a signal charge, a charge storage unit that stores a signal charge transferred from the photoelectric conversion unit, and the photoelectric conversion unit from the photoelectric conversion unit A plurality of pixels including a transistor having a control electrode for transferring charge to the charge storage portion, and a floating diffusion portion to which the signal charge of the charge storage portion is transferred;
A waveguide for guiding incident light to the photoelectric conversion unit;
A light shielding portion provided to cover at least the charge accumulation portion,
The light shielding portion is disposed along the surface of the semiconductor substrate so as to cover a first portion covering the control electrode and an insulating layer on the semiconductor substrate and to cover a part of the photoelectric conversion portion. And a second portion extending
The insulating layer is disposed between the waveguide and the semiconductor substrate;
An interval between the waveguide and the semiconductor substrate is larger than an interval between the second portion of the light shielding portion and the semiconductor substrate, and an upper surface of the second portion of the light shielding portion and the semiconductor substrate A solid-state imaging device characterized by being smaller than the distance. The waveguide has an incident part where light is incident and an emission part which emits light,
The solid-state imaging device according to claim 1, wherein the light shielding unit includes an opening that allows light emitted from the waveguide to pass therethrough.   The at least part of the edge part of the said opening part of the said light-shielding part is located between the said incident part and the said output part seeing from the optical axis direction of the said waveguide. Solid-state imaging device.   3. The solid-state imaging device according to claim 2, wherein the width of the opening of the light shielding portion is larger than the width of the emitting portion and smaller than the width of the incident portion.   In at least one pixel, when viewed from the optical axis direction of the waveguide, the position of the center of gravity of the emitting portion is shifted in the direction of the center of the plurality of pixels with respect to the position of the center of gravity of the opening of the light shielding portion. The solid-state imaging device according to claim 2, wherein the solid-state imaging device is provided.   6. The solid-state imaging device according to claim 1, wherein a lower surface of the waveguide includes an interface between the waveguide and an etching stop layer.   The solid-state imaging device according to claim 1, wherein a lower surface of the waveguide includes an interface between the waveguide and an interlayer insulating layer.   The solid-state imaging device according to claim 1, wherein a lower surface of the waveguide has a stepped shape. A plurality of wiring layers disposed on the light shielding portion;
The solid-state imaging device according to claim 1, wherein the waveguide penetrates the plurality of wiring layers. A semiconductor substrate;
A photoelectric conversion unit that is arranged on the semiconductor substrate and photoelectrically converts incident light to generate a signal charge, a charge storage unit that stores a signal charge transferred from the photoelectric conversion unit, and the photoelectric conversion unit from the photoelectric conversion unit A plurality of pixels including a transistor having a control electrode for transferring charge to the charge storage portion, and a floating diffusion portion to which the signal charge of the charge storage portion is transferred;
A waveguide for guiding incident light to the photoelectric conversion unit;
A light shielding portion covering at least the control electrode and the charge storage portion;
A plurality of wiring layers disposed on the light shielding portion,
The waveguide has an upper end located at a position farther from the semiconductor substrate than at least a part of the plurality of wiring layers, and a lower end located at a position closer to the semiconductor substrate than the at least a part of the plurality of wiring layers. And
An insulating layer is disposed between the lower end of the waveguide and the semiconductor substrate;
The solid-state imaging device, wherein an interval between the lower end of the waveguide and the semiconductor substrate is larger than an interval between the upper end of the light shielding unit and the semiconductor substrate.   11. The solid-state imaging according to claim 10, wherein at least a part of an end of the opening of the light shielding part is located between the upper end and the lower end when viewed from the optical axis direction of the waveguide. apparatus.   The solid-state imaging device according to claim 10, wherein a width of the opening of the light shielding portion is larger than a width of the lower end and smaller than a width of the upper end.   The solid-state imaging device according to claim 10, wherein the lower end of the waveguide includes an interface between the waveguide and an etching stop layer.   The solid-state imaging device according to any one of claims 10 to 12, wherein the lower end of the waveguide includes an interface between the waveguide and an interlayer insulating layer.   The solid-state imaging device according to claim 10, wherein the lower end of the waveguide has a stepped shape. A semiconductor substrate;
A photoelectric conversion unit that is arranged on the semiconductor substrate and photoelectrically converts incident light to generate a signal charge, a charge storage unit that stores a signal charge transferred from the photoelectric conversion unit, and the photoelectric conversion unit from the photoelectric conversion unit A plurality of pixels including a transistor having a control electrode for transferring charge to the charge storage portion, and a floating diffusion portion to which the signal charge of the charge storage portion is transferred;
A waveguide for guiding incident light to the photoelectric conversion unit;
A light shielding portion covering at least the control electrode and the charge storage portion;
A plurality of wiring layers disposed on the light shielding portion,
The waveguide includes a portion arranged at the same height as the wiring of the first layer included in the plurality of wiring layers, and a second layer different from the first layer included in the plurality of wiring layers. And a portion arranged at the same height as the wiring,
An insulating layer is disposed between the waveguide and the semiconductor substrate;
The solid-state imaging device, wherein an interval between the waveguide and the semiconductor substrate is larger than an interval between an upper end of the light shielding unit and the semiconductor substrate. A solid-state imaging device according to any one of claims 1 to 16,
A video signal processing unit for processing a signal output from the solid-state imaging device;
An imaging system comprising:

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