JP5735318B2 - Solid-state imaging device and electronic information device - Google Patents

Description

  The present invention relates to a solid-state image sensor composed of a semiconductor element that captures an image by photoelectrically converting image light from a subject, such as a digital video camera and a digital still camera using the solid-state image sensor as an image input device in an imaging unit. The present invention relates to an electronic information device such as a digital camera, an image input camera such as a surveillance camera, a scanner device, a facsimile device, a television phone device, and a camera-equipped mobile phone device.

  As a conventional solid-state imaging device of this type, in Patent Document 1, by forming a circuit element, a wiring layer, or the like on the front surface side of the silicon substrate and allowing light to enter from the back surface side of the silicon substrate, A so-called back-illuminated solid-state imaging device has been proposed in which the aperture ratio for light reception can be increased by the absence of circuit elements and wiring layers on the back side, and absorption or reflection of incident light can be suppressed.

  FIG. 6 is a longitudinal cross-sectional view showing an example of a configuration of a main part of a conventional backside illumination type solid-state imaging device disclosed in Patent Document 1.

In FIG. 6, in a CMOS image sensor 100 as a conventional back-illuminated solid-state imaging device, a wafer is polished by CMP (Chemical Mechanical Polishing) to thereby form a silicon (Si) layer (element layer) having a thickness of about 10 to 20 μm. ) 101 is formed. A light shielding film 103 is formed on one surface side of the silicon layer 101 with an SiO ₂ film 102 interposed therebetween.

  Unlike the wiring, the light shielding film 103 is laid out in consideration of only optical elements. An opening 103 a is formed in the light shielding film 103. On the light shielding film 103, a silicon nitride film (SiN) 104 is formed as a passivation film, and further, a color filter 105 and a micro lens 106 are formed thereon above the opening 103a.

  That is, light incident from one surface side of the silicon layer 101 is guided to the light receiving surface of the photodiode 107 formed on the silicon layer 101 via the microlens 106 and the color filter 105. On the other surface side of this silicon layer 101 (the lower side in FIG. 6), a wiring layer 108 on which transistors, metal wirings and the like are formed is formed, and a substrate support material 109 is further attached below the wiring layer 108. . Reference numeral 110 denotes a pixel area, and 111 denotes a peripheral circuit area.

Here, in the conventional CMOS image sensor as the surface light-receiving solid-state imaging device, the wiring layer 108 side is the front surface side, whereas the surface light-receiving pixel structure that takes in incident light from the wiring layer 108 side is adopted. In this CMOS image sensor 100, incident light is taken in from the side opposite to the wiring layer 108 (back side; upper side in FIG. 6). As is apparent from the backside light receiving pixel structure, the light shielding layer 103 is only present as a metal layer between the microlens 106 and the photodiode 107, and the light shielding layer 103 from the photodiode 107 is also present. Since the height is lower than the thickness of the SiO ₂ film 102 (for example, about 0.5 μm), it is possible to eliminate the limitation of light collection due to “scratching” in the metal layer.

  FIG. 7 schematically shows an example of a main part configuration in which an effective pixel array, an optical black region, and a peripheral circuit region are provided from the center in a chip-type CMOS solid-state image pickup device as a conventional back-surface light-receiving solid-state image pickup device. FIG. FIG. 8 is a longitudinal sectional view taken along the line AA ′ of FIG. 7.

  7 and 8, in a chip-type CMOS solid-state image pickup device 200 as a conventional back-surface light-receiving solid-state image pickup device, an effective pixel array region 201 in a central portion in which a plurality of pixel portions are arranged in a matrix, An optical black region 202 for obtaining a black reference formed on the peripheral side of the effective pixel array region 201 and a peripheral circuit region 203 formed on the peripheral side of the optical black region 202 are provided.

  The optical black region 202 has a configuration in which pixels for correcting noise such as dark current are arranged around the effective pixel array 201, and is covered with a metal light shielding film 206 via an insulating film 205 on the back surface of the silicon substrate 204. Yes. By correcting the image pickup signal output from the effective pixel array area 201 with the black signal output from the optical black area 202 as a reference, black level correction for removing noise such as dark current is performed.

  In the effective pixel array region 201, a plurality of photoelectric conversion elements (light receiving portions) made of high-concentration N-type semiconductor regions are arranged in a matrix in a unit pixel region delimited by an element isolation region formed in the silicon substrate 204. Is formed. On the first surface side of the silicon substrate 204, that is, on the surface side (lower side in FIG. 8), readout circuits for reading out signal charges accumulated in the photoelectric conversion elements are formed for each pixel. A gate 207 of the transistor and a wiring layer 208 connected thereto are formed.

Further, on the second surface side of the silicon substrate 204, that is, the back surface side (upper side in FIG. 8), each unit pixel region is placed on the effective pixel array region 201 via an insulating film 205 (SiO ₂ film, SiN film, etc.). The color filters 209 of different colors are formed at predetermined positions according to the predetermined arrangement rule (for example, Bayer arrangement). On-chip lenses 210 are formed at positions corresponding to the photoelectric conversion elements on the color filters 209, respectively.

  Furthermore, the metal light-shielding film 206 is formed so as to continuously cover the photoelectric conversion element and the peripheral circuit region 203 in the optical black region 202. In the CMOS solid-state imaging device 200 having such a configuration, image light is incident from the second surface side of the silicon substrate 204, that is, the back surface side (upper side in FIG. 8). Although not shown, a planarizing film made of a passivation film is formed on the insulating film 211 on the first surface side of the silicon substrate 204, that is, on the surface side (lower side in FIG. 8). A support substrate (not shown) is bonded.

  Next, a stress relaxation region in a conventional surface irradiation type solid-state imaging device will be described.

  FIG. 9 is a longitudinal sectional view showing an example of the configuration of the main part of a conventional surface irradiation type solid-state imaging device disclosed in Patent Document 2. As shown in FIG.

  In FIG. 9, a conventional surface irradiation type solid-state imaging device 300 transfers a signal charge of a light receiving unit 302 and a light receiving unit 302 that photoelectrically converts incident light to each of a plurality of pixel units on a semiconductor substrate 301. A charge transfer transistor 303; a floating diffusion 304 in which a signal charge is transferred from the light receiving unit 302 by the charge transfer transistor 303; and a voltage conversion thereby; and a transistor 305 constituting a signal read circuit provided via an isolation insulating layer; Is provided. Multi-layered wiring layers 307 and 307a are provided via contact plugs 306 connected to the gate of the charge transfer transistor 303, the floating diffusion 304, the transistor 305, and the like. The contact plug 306 and the wiring layer 307 are provided in each insulating layer 308, 308a in three stages.

  A stress relaxation region 311 is provided between the optical black pixel region 309 and the peripheral region 310. The stress alleviating region 311 includes an air layer, and in a plurality of metal wirings 307, stress propagating to the optical black pixel region 309 is mitigated by the metal wirings 307 and 307a provided in the peripheral region 310. The stress relaxation layers 311 a to 311 c in the stress relaxation region 311 are air layers and are provided so as to penetrate the insulating film 308 a. The light receiving portion 302, the charge transfer transistor 303 and the floating diffusion 304 constitute a light-shielding pixel portion 312, and the transistor 305 constitutes a peripheral circuit element 313.

JP 2003-31785 A JP 2010-232284 gazette

  In the configuration of the conventional CMOS image sensor 100 as the back-illuminated solid-state image sensor in FIG. 6 and the CMOS solid-state image sensor 200 as the back-illuminated solid-state image sensor in FIGS. On the second surface side of the silicon layer, that is, the back surface side, the peripheral circuit region and the optical black region inside thereof are shielded by providing one more light shielding film above the silicon layer in order to avoid generation of unnecessary electrons due to light. ing. The metal material constituting the metal film used as the light-shielding film has a higher stress (stress) than the insulating material constituting the insulating film. The stress (stress) of the metal film causes strain in the silicon layer and causes dark current in the silicon layer. As a result, the dark current in the optical black area increases, causing a dark output difference between the pixel portions of the optical black area and the effective pixel array area, which makes it difficult to correct the black level.

  In the conventional front-illuminated solid-state imaging device 300 of FIG. 9 disclosed in Patent Document 2, the stress from the peripheral region 310 having a high wiring density is not propagated to the optical black pixel region 309 side having a low wiring density. Between the peripheral region 310 and the optical black pixel region 309, an air layer is provided on the insulating film 308a in the stress relaxation region 311 provided with the metal wiring 307. This is a front-illuminated solid-state imaging device 300, and the silicon layer is distorted by stress caused by a metal light-shielding film between the peripheral circuit portion and the optical black region in the back-illuminated solid-state imaging device. The problem is completely different from the problem that dark level is generated in the silicon layer and black level correction is difficult.

  The present invention solves the above-described conventional problems, and can suppress dark current caused by stress (stress) of a metal light-shielding film and can perform black level correction more accurately, and the solid-state imaging device. An object of the present invention is to provide an electronic information device such as a mobile phone device with a camera using an element as an image input device in an imaging unit.

  In the solid-state imaging device of the present invention, an effective pixel array region for capturing an image by photoelectrically converting incident light from a subject is provided above a semiconductor substrate, and the effective pixel is disposed on the outer peripheral side of the effective pixel array region. In a solid-state imaging device in which an optical black region for performing black level correction on an imaging signal from an array region is provided, and a peripheral circuit region is provided on the outer peripheral side of the optical black region, the optical black region and the peripheral A light shielding film for shielding incident light is provided in the circuit area, and a slit portion for releasing stress is provided at all or part of the boundary between the optical black area and the light shielding film in the peripheral circuit area. This achieves the above object.

  Preferably, the slit portion in the solid-state imaging device of the present invention is configured such that the stress of the light shielding film in the peripheral circuit region is not transmitted to or hardly transmitted to the light shielding film in the optical black region and the semiconductor layer under the light shielding film. It is a buffer part.

  Further preferably, the slit portion in the solid-state imaging device of the present invention is formed over the outer peripheral side of at least one side of the effective pixel array region and the optical black region on the outer peripheral side of the quadrangle in plan view.

  Further preferably, the slit portion in the solid-state imaging device of the present invention is formed over the outer periphery of the effective pixel array region and the outer periphery of the optical black region on the outer peripheral side thereof in a square view.

  Further preferably, the slit portions in the solid-state imaging device of the present invention are formed on the two opposing left and right or upper and lower sides of the effective pixel array region and the square of the optical black region on the outer periphery thereof in plan view.

  Still preferably, in a solid-state imaging device according to the present invention, the slit portion excludes a square shape or a rectangular shape at least at an outer peripheral corner from a quadrangular shape in plan view of the effective pixel array region and the optical black region on the outer peripheral side thereof. It is formed over the whole or part of the outer periphery of the entire shape including the concave shape.

  Furthermore, it is preferable that a light shielding film for the optical black region is not provided in at least one corner portion of the optical black region of the solid-state imaging device according to the present invention having a quadrangular shape in plan view.

  Further preferably, the semiconductor substrate protrudes from a quadrangular ring-shaped light shielding film in the peripheral circuit region of the solid-state imaging device of the present invention into a region in which at least one corner of the optical black region has a quadrangular shape in a plan view is recessed. A light-shielding film in the peripheral circuit region is added to at least one corner side of the inner periphery so as to cover the top.

  Further preferably, the slit portion provided between the optical black region and the peripheral circuit region in the solid-state imaging device of the present invention is formed in a ring shape with the same width so as to surround the outer peripheral side of the optical black region. .

  Further preferably, the optical black region is provided on an outer peripheral side of at least one side of a quadrangle in a plan view of the effective pixel array region in the solid-state imaging device of the present invention, and the slit portion is formed on the outer periphery of the optical black region. It is formed across.

  Further, preferably, the slit portion in the solid-state imaging device of the present invention is provided continuously or intermittently.

  Furthermore, it is preferable that the semiconductor layer of the semiconductor substrate corresponding to the lower portion of the solid-state imaging device of the present invention is an inactive region where no active device is disposed.

  Further preferably, the light shielding film in the solid-state imaging device of the present invention is a metal light shielding film, and is made of any one of an aluminum material (Al), a tungsten material (W), and a titanium material (Ti or TiN). ing.

  Further preferably, a plurality of photoelectric conversion elements are formed in the semiconductor layer of the semiconductor substrate in the effective pixel array region and the optical black region on the first surface side of the semiconductor substrate in the solid-state imaging device of the present invention. The light shielding film is formed on the second surface side of the semiconductor substrate in the optical black region and the peripheral circuit region, and image light is incident from the second surface side in the effective pixel array region, and the plurality of photoelectric conversions This is a back-illuminated solid-state imaging device that captures an image with the device.

  The electronic information device of the present invention uses the solid-state imaging device of the present invention as an image input device in an imaging unit, and thereby achieves the above object.

  With the above configuration, the operation of the present invention will be described below.

  In the present invention, an effective pixel array region for capturing an image by photoelectrically converting incident light from a subject is provided above the semiconductor substrate, and imaging from the effective pixel array region is provided on the outer peripheral side of the effective pixel array region. In a solid-state imaging device in which an optical black region for correcting a black level for a signal is provided and a peripheral circuit region is provided on the outer peripheral side of the optical black region, incident light is shielded from the optical black region and the peripheral circuit region. A light shielding film is provided, and a slit portion for releasing stress is provided in all or a part of the boundary between the optical black region and the peripheral circuit region.

  As a result, the stress of the light shielding film is released at the slit portion, so that dark current due to the stress (stress) of the metal light shielding film can be suppressed and black level correction can be performed more accurately.

  As described above, according to the present invention, since the slit portion for releasing the stress is provided in all or part of the boundary between the optical black region and the peripheral circuit region, the stress (stress) of the metal light shielding film is provided. The black level correction can be performed more accurately by suppressing the dark current caused by ().

It is a top view which shows typically the example of a principal part structure of the CMOS solid-state image sensor of the chip state in Embodiment 1 of this invention. FIG. 2 is a longitudinal sectional view taken along line BB ′ in FIG. 1. It is a top view which shows typically the example of a principal part structure of the CMOS type solid-state image sensor of the chip state in Embodiment 2 of this invention. FIG. 4 is a longitudinal sectional view taken along line CC ′ of FIG. 3. It is a block diagram which shows the example of schematic structure of the electronic information device which used the solid-state image sensor of Embodiment 1, 2 of this invention for the imaging part as Embodiment 3 of this invention. It is a longitudinal cross-sectional view which shows the principal part structural example of the conventional backside illumination type solid-state image sensor currently disclosed by patent document 1. FIG. FIG. 4 is a plan view schematically showing an example of a configuration of a main part in which an effective pixel array, an optical black region, and a peripheral circuit region are provided from the center in a chip-type CMOS solid-state image sensor as a conventional backside light-receiving solid-state image sensor. is there. FIG. 8 is a vertical sectional view taken along line AA ′ of FIG. 7. It is a longitudinal cross-sectional view which shows the principal part structural example of the conventional surface irradiation type solid-state image sensor currently disclosed by patent document 2. FIG.

  Embodiments 1 and 2 of the solid-state imaging device of the present invention, and implementation of electronic information equipment such as a mobile phone device with a camera using the embodiments 1 and 2 of the solid-state imaging device as image input devices in an imaging unit are described below. The third embodiment will be described in detail with reference to the drawings. In addition, each thickness, length, etc. of the structural member in each figure are not limited to the structure to illustrate from a viewpoint on drawing preparation.

(Embodiment 1)
FIG. 1 is a plan view schematically showing a configuration example of a main part of a CMOS solid-state imaging device in a chip state according to Embodiment 1 of the present invention. 2 is a longitudinal sectional view taken along the line BB ′ of FIG.

  1 and 2, the CMOS solid-state imaging device 1 in the chip state according to the first embodiment has a central effective pixel array region in which a plurality of light-receiving portions that photoelectrically convert incident light to form an image are arranged in a matrix. 2, an optical black region 3 for obtaining a black reference formed on the peripheral side of the effective pixel array 2, a peripheral circuit region 4 formed on the peripheral side of the optical black region 3, and the optical black region 3 and the peripheral The slit portion 5 is provided between the circuit regions 4 and extends over the entire outer peripheral side of the optical black region 3.

  In the effective pixel array region 2, a plurality of photoelectric conversion elements (light receiving portions) made of high-concentration N-type semiconductor regions are arranged in a matrix direction in a unit pixel region delimited by an element isolation region formed in the silicon substrate 6. It is formed in a matrix. On the first surface side of the silicon substrate 6, that is, on the front surface side (lower side in FIG. 2), readout circuits for reading out signal charges accumulated in the respective light receiving units are formed for each pixel unit. A gate 9 of the transistor and a wiring layer 10 connected to the gate 9 are formed.

On the second surface side of the silicon substrate 6, that is, on the back surface side (upper side in FIG. 2), each unit pixel region (light receiving) on the effective pixel array region 2 via an insulating film 7 (SiO ₂ film, SiN film, etc.). The color filters 11 of different colors are formed at predetermined positions (for example, Bayer array) at positions corresponding to the (part). On-chip lenses 12 are formed at positions corresponding to the respective light receiving portions on the respective color filters 11.

  In the optical black region 3, a plurality of rows of photoelectric conversion elements (photodiodes) composed of high-concentration N-type semiconductor regions are formed in a unit pixel region delimited by an element isolation region formed in the silicon substrate 6, for example, 4, It is formed in 5 rows. On the first surface side of the silicon substrate 6, that is, on the front surface side (lower side in FIG. 2), readout circuits for reading out signal charges accumulated in the photoelectric conversion elements are formed for the respective pixel units. A gate 9 of the transistor and a wiring layer 10 connected thereto are formed on the top.

  The optical black region 3 has a configuration in which pixels for correcting noise such as dark current are arranged in several rows to several tens rows around the outer periphery of a rectangular or square in a plan view of the effective pixel array region 2, and on the back surface of the silicon substrate 6. In addition to the aluminum material (Al) and the tungsten material (W), the insulating film 7 is covered with a metal light shielding film 8a such as a titanium material (Ti or TiN). By correcting (difference) the imaging signal output from the effective pixel array region 2 with the black signal output from the optical black region 3 as a reference, black level correction for removing noise such as dark current is performed.

  In the peripheral circuit region 4, a read drive circuit that drives each read circuit that reads signal charges from each photoelectric conversion element in the effective pixel array region 2 and the optical black region 3 is provided. On the first surface side of the silicon substrate 6 in the peripheral circuit region 4, that is, on the surface side (lower side in FIG. 2), the gate 9 and source / drain regions of the transistor of this read drive circuit, and the wiring layer 10 connected thereto. Is formed with high density.

  In the peripheral circuit region 4, the back surface of the silicon substrate 6 is covered with a metal light shielding film 8 b such as an aluminum material (Al), a tungsten material (W), or a titanium material (Ti or TiN) via an insulating film 7. At the boundary between the metal light-shielding film 8b in the peripheral circuit region 4 and the metal light-shielding film 8a in the optical black region 3, a slit 5a (elongated gap) for releasing the metal film stress is formed on the outer periphery of the optical black region 3. It is formed across. The slit region 5 in which the slit 5a is formed is an inactive region without disposing an active element such as a transistor on the surface side of the silicon substrate 6.

  That is, on the second surface side of the silicon substrate 6, that is, on the back surface side (upper side in FIG. 2), the metal light shielding film 8 a that covers the photoelectric conversion element in the optical black region 3 is formed, and the metal light shielding film that covers the peripheral circuit region 4 is formed. A film 8b is formed. A slit for releasing the metal film stress is provided at the boundary between the optical black region 3 and the peripheral circuit region 4. The width of the slit 5a is about several μm, for example, about 3 μm. The slit 5a is laid out so that there are no active elements in the peripheral circuit on the first surface side, that is, the front surface side (lower side in FIG. 2).

  Although not shown, a planarizing film made of a passivation film is formed on the insulating film 13 on the first surface side of the silicon substrate 6, that is, on the surface side (lower side in FIG. 2). A support substrate (not shown) is bonded.

  As described above, according to the first embodiment, the effective pixel array region 2 that captures an image by photoelectrically converting incident light from the subject is provided above the semiconductor substrate 6 at the center, and the outer peripheral side of the effective pixel array region 2 Further, in the solid-state imaging device 1 in which an optical black region 3 for performing black level correction on an imaging signal from the effective pixel array region 2 is provided and a peripheral circuit region 4 is provided on the outer peripheral side of the optical black region 3. The optical black region 3 and the peripheral circuit region 4 are provided with metal light shielding films 8a and 8b for shielding incident light, and stress is applied to all of the boundaries between the optical black region 3 and the peripheral circuit region 4 between the metal light shielding films 8a and 8b. A slit portion 5 for opening is provided. The slit portion 5 is a buffer region in which the stress of the metal light-shielding film 8b in the peripheral circuit region 4 is not transmitted to or hardly transmitted to the metal light-shielding film 8a in the optical black region 3 and the semiconductor layer therebelow. The slits 5a are formed over the outer periphery of the effective pixel array region 2 and the optical black region 3 on the outer peripheral side thereof in a quadrangular shape in plan view.

  As described above, the stress of the metal light shielding film 8b is released by the slit 5a, so that the distortion of the silicon layer due to the metal light shielding film 8a in the optical black region 3 is reduced, and the darkness of the optical black region 3 and the effective pixel array region 2 is reduced. A CMOS solid-state imaging device 1 which is a back-illuminated CMOS image sensor that obtains a more accurate reference voltage with a small time output difference can be obtained.

  In the first embodiment, the slit 5a is formed at the boundary between the optical black region 3 and the metal light-shielding film 8a over the entire outer periphery of the optical black region 3. However, the present invention is not limited to this. You may form in a part of outer periphery of the area | region 3. FIG. In this case, the outer periphery of the optical black region 3 may be formed with slits 5a on at least one side of a quadrangular shape in plan view, or the slits 5a may be formed intermittently (dot-like) on all four sides or on at least one side. It may be formed. When the slits 5a are provided on the sides, it is preferable to provide the slits 5a at symmetrical positions such as the left and right sides or the upper and lower sides in a plan view quadrangle. That is, the slit part 5 should just be formed in the left-right or up-and-down two opposing sides of the effective pixel array area | region 2 and the optical black area | region 3 of the outer peripheral side of the tetragonal plane view.

(Embodiment 2)
FIG. 3 is a plan view schematically showing a configuration example of a main part of a chip-type CMOS solid-state imaging device according to Embodiment 2 of the present invention. 4 is a longitudinal sectional view taken along the line CC ′ of FIG. 3 and 4, the same reference numerals are used for the description of the structural members that have the same operational effects as the structural members of FIGS. 1 and 2.

  3 and 4, the CMOS solid-state imaging device 1A in the chip state according to the first embodiment has a central effective pixel array region in which a plurality of light-receiving portions that photoelectrically convert incident light to form an image are arranged in a matrix. 2 and an optical black region 3A for obtaining a black reference formed on the outer peripheral four sides other than the corners of the rectangular region in plan view of the effective pixel array 2, and a ring shape on the outer peripheral side of the optical black region 3A The peripheral circuit region 4 is formed, and the slit portion 5A is provided between the optical black region 3A and the peripheral circuit region 4 and extends over the entire outer peripheral side of the optical black region 3A.

  In the effective pixel array region 2, a plurality of photoelectric conversion elements (light receiving portions) made of high-concentration N-type semiconductor regions are arranged in a matrix direction in a unit pixel region delimited by an element isolation region formed in the silicon substrate 6. It is formed in a matrix. On the first surface side of the silicon substrate 6, that is, on the front surface side (lower side in FIG. 4), readout circuits for reading out signal charges accumulated in the respective light receiving units are formed for each pixel unit. A gate 9 of the transistor and a wiring layer 10 connected to the gate 9 are formed.

On the second surface side of the silicon substrate 6, that is, on the back surface side (upper side in FIG. 2), each unit pixel region (light receiving) on the effective pixel array region 2 via an insulating film 7 (SiO ₂ film, SiN film, etc.). The color filters 11 of different colors are respectively formed in predetermined positions (for example, Bayer array) at positions corresponding to the (part). On-chip lenses 12 are formed at positions corresponding to the respective light receiving portions on the respective color filters 11.

  In the optical black region 3A, a plurality of rows of photoelectric conversion elements (photodiodes) composed of high-concentration N-type semiconductor regions are formed in a unit pixel region partitioned by an element isolation region formed in the silicon substrate 6, for example, 4, It is formed in 5 rows. On the first surface side of the silicon substrate 6, that is, on the front surface side (lower side in FIG. 4), readout circuits for reading out signal charges accumulated in the photoelectric conversion elements are formed for the respective pixel units. A gate 9 of the transistor and a wiring layer 10 connected thereto are formed on the top.

  The optical black region 3A has a configuration in which pixels for correcting noise such as dark current are arranged in several rows to several tens of rows around the outer periphery of the quadrangle in a plan view of the effective pixel array region 2, and on the back surface of the silicon substrate 6. In addition to the aluminum material (Al) and the tungsten material (W), the insulating film 7 is covered with a metal light shielding film 8c such as a titanium material (Ti or TiN). By correcting (difference) the imaging signal output from the effective pixel array region 2 with the black signal output from the optical black region 3A as a reference, black level correction for removing noise such as dark current is performed.

  In the peripheral circuit region 4, a read drive circuit for driving each read circuit that reads signal charges from the photoelectric conversion elements in the effective pixel array region 2 and the optical black region 3A is provided. On the first surface side of the silicon substrate 6 in the peripheral circuit region 4, that is, on the surface side (lower side in FIG. 4), the gate 9 and source / drain regions of the transistor of this read drive circuit, and the wiring layer 10 connected thereto. Is formed with high density.

  In the peripheral circuit region 4, the back surface of the silicon substrate 6 is covered with a metal light shielding film 8 b such as an aluminum material (Al), a tungsten material (W), or a titanium material (Ti or TiN) via an insulating film 7. At the boundary between the metal light-shielding film 8b in the peripheral circuit region 4 and the metal light-shielding film 8c in the optical black region 3A, a slit 5b for releasing the metal film stress extends around the outer periphery of the optical black region 3A. Is formed. The slit region 5A in which the slit 5b is formed is an inactive region without arranging an active element such as a transistor on the surface side of the silicon substrate 6.

  That is, on the second surface side of the silicon substrate 6, that is, the back surface side (upper side in FIG. 4), a metal light shielding film 8c that covers each photoelectric conversion element in the optical black region 3A is formed and the metal that covers the peripheral circuit region 4 is formed. A light shielding film 8b is formed. A slit 5b for releasing metal film stress is provided as a break at the boundary between the optical black region 3A and the peripheral circuit region 4. The width of the slit 5b is about several μm, for example, about 3 μm. The slit 5b is laid out so that there are no active elements in the peripheral circuit on the first surface side, that is, on the surface side (lower side in FIG. 4).

  Actually, since a photoelectric conversion element (photodiode) does not exist in the rectangular ring-shaped quadrangular portion of the optical black region 3A in plan view, a metal is not present in the rectangular ring-shaped quadrangular square portion of the optical black region 3A in plan view. The light shielding film 8c is not provided. In short, the slit portion 5A is formed over the entire outer periphery of the effective pixel array region 2 and the optical black region 3A on the outer peripheral side thereof excluding the square shape of the outer peripheral four corners from the rectangular shape in plan view. Yes.

  A planarizing film made of a passivation film is formed on the insulating film 13 on the first surface side of the silicon substrate 6, that is, on the front surface side (lower side in FIG. 4), but is formed on the planarizing film. A support substrate (not shown) is bonded.

  As described above, according to the second embodiment, the stress of the metal light shielding film 8b in the peripheral circuit region 4 is released by the slit 5b that is a cut, and the metal light shielding film 8c in the optical black region 3A and the silicon substrate 6 therebelow. Is not transmitted to the silicon layer, so that the distortion of the silicon layer in the optical black region 3A is reduced, the difference in dark output between the optical black region 3A and the effective pixel array region 2 is small, and the backside illumination to obtain a more accurate reference potential A CMOS type solid-state imaging device 1A which is a type CMOS image sensor can be obtained. In particular, in the second embodiment, since the metal light shielding film 8c is not provided in the quadrangular square portion of the rectangular ring shape in plan view of the optical black region 3A, the area of the metal light shielding film is reduced accordingly. The influence of the stress due to 8c on the silicon layer is reduced, and the distortion of the silicon layer in the optical black region 3A is further reduced compared to the case of the first embodiment, and the optical black region 3A and the effective pixel array region 2 are reduced. It is possible to obtain a CMOS solid-state imaging device 1A that is a backside illumination type CMOS image sensor that has a smaller output difference in the dark and obtains a more accurate reference potential.

  In the second embodiment, as shown in FIG. 3, since there is no photoelectric conversion element (photodiode) in the square square part of the quadrangular ring shape in plan view of the optical black area 3A, the optical black area 3A Although the case where the metal light-shielding film 8c is not provided in the quadrangular ring-shaped square square portion in plan view has been described, the present invention is not limited to this, but within the four corners of the square ring-shaped metal light-shielding film 8b in the peripheral circuit region 4 The region of the rectangular ring-shaped metal light-shielding film 8b in the peripheral circuit region 4 is projected to cover the square portion of the rectangular ring shape in the plan view of the optical black region 3A from the peripheral side. It may be added to. In this case, the quadrangular ring-shaped metal light-shielding film 8b in the peripheral circuit region 4 protrudes from the rectangular region of the optical black region 3A in the four-sided shape in the plan view so as to cover the semiconductor substrate 6 so as to cover the semiconductor substrate 6. Metal light shielding films 8b in the peripheral circuit region 4 are added to the four corners on the inner periphery. In short, in this case, the slit portion 5A provided between the optical black region 3A and the peripheral circuit region 4 surrounds the outer peripheral side of the optical black region 3A in a ring shape with the same width. Thereby, arrangement (layout) of active elements such as transistors in the peripheral circuit region 4 becomes easier.

  In the second embodiment, the slit portion 5A extends over the outer periphery of the effective pixel array region 2 and the optical black region 3A on the outer peripheral side thereof excluding the square shape of the outer peripheral corner portion from the rectangular shape in plan view. However, the present invention is not limited to this, and the square shape or the rectangular shape of at least one corner of the outer periphery is excluded from the rectangular shape in plan view of the effective pixel array region 2 and the optical black region 3A on the outer periphery thereof. It may be formed over the outer periphery of the shape. Further, an optical black region may be provided on the outer peripheral side of at least one side of the effective pixel array region 2 in a plan view quadrangle, and the slit portion may be formed all or part of the outer periphery of the optical black region. Good. The slit part in the above case should just be provided continuously or intermittently.

  In the second embodiment, the slit 5b is formed at the boundary between the optical black region 3A and the metal light-shielding film 8c over the entire outer periphery of the optical black region 3A. May be formed on a part of the outer periphery of the optical black region 3A. In this case, the outer periphery of the optical black region 3A may be formed with a slit 5b on at least one side of a quadrangular shape in plan view, or in all four side and four side recesses, or at least one side and / or four sides. The slit 5b may be formed intermittently (dot-like) in at least one of the four recesses. When the slit 5b is provided in a side or a quadrangular recess, the slit 5b is provided at a symmetrical position such as a left and right side or upper and lower sides in a square shape in plan view, and a diagonal side recess of the four corners. It is better to provide it.

(Embodiment 3)
FIG. 5 is a block diagram showing a schematic configuration example of an electronic information device using the solid-state imaging device according to Embodiments 1 and 2 of the present invention as an imaging unit as Embodiment 3 of the present invention.

  In FIG. 5, an electronic information device 90 according to the third embodiment includes a solid-state imaging device 91 that obtains a color image signal by performing predetermined signal processing on the imaging signal from the solid-state imaging device 1 or 1A according to the first and second embodiments. The color image signal from the solid-state image pickup device 91 is subjected to predetermined signal processing for recording, and then a memory unit 92 such as a recording medium capable of recording data, and the color image signal from the solid-state image pickup device 91 is predetermined for display. The display unit 93 such as a liquid crystal display device which can be displayed on a display screen such as a liquid crystal display screen after the signal processing is performed, and the color image signal from the solid-state imaging device 91 is subjected to predetermined signal processing for communication and then communicated A communication unit 94 such as a transmission / reception device that can be processed, and a color image signal from the solid-state imaging device 91 that has been subjected to predetermined print signal processing for printing, and can be printed. And an image output unit 95 such as a. The electronic information device 90 is not limited to this, but in addition to the solid-state imaging device 91, at least one of a memory unit 92, a display unit 93, a communication unit 94, and an image output unit 95 such as a printer. You may have.

  As described above, the electronic information device 90 includes, for example, a digital camera such as a digital video camera and a digital still camera, an in-vehicle camera such as a surveillance camera, a door phone camera, and an in-vehicle rear surveillance camera, and a video phone camera. An electronic device having an image input device such as an image input camera, a scanner device, a facsimile device, a camera-equipped mobile phone device, and a portable terminal device (PDA) is conceivable.

  Therefore, according to the third embodiment, based on the color image signal from the solid-state imaging device 91, it can be displayed on the display screen, or can be printed out on the paper by the image output unit 95. (Printing), communicating this as communication data in a wired or wireless manner, performing a predetermined data compression process in the memory unit 92 and storing it in a good manner, or performing various data processings satisfactorily Can do.

  Although not described in detail in the first and second embodiments, an effective pixel array region for capturing an image by photoelectrically converting incident light from a subject is provided above the semiconductor substrate. An optical black area is provided on the outer peripheral side of the effective pixel array area to perform black level correction on the image pickup signal from the effective pixel array area, and a peripheral circuit area is provided on the outer peripheral side of the optical black area. In the solid-state imaging device, a light-shielding film that shields incident light is provided in the optical black region and the peripheral circuit region, and stress is released to all or part of the boundary between the optical black region and the light-shielding film in the peripheral circuit region. The slit part for performing is provided. This alone can achieve the object of the present invention in which the dark current can be corrected more accurately by suppressing the dark current caused by the stress of the metal light-shielding film.

  As mentioned above, although this invention has been illustrated using preferable Embodiment 1-3 of this invention, this invention should not be limited and limited to this Embodiment 1-3. It is understood that the scope of the present invention should be construed only by the claims. It is understood that those skilled in the art can implement an equivalent range based on the description of the present invention and the common general technical knowledge from the description of specific preferred embodiments 1 to 3 of the present invention. Patents, patent applications, and documents cited herein should be incorporated by reference in their entirety, as if the contents themselves were specifically described herein. Understood.

  The present invention relates to a solid-state image sensor composed of a semiconductor element that captures an image by photoelectrically converting image light from a subject, such as a digital video camera and a digital still camera using the solid-state image sensor as an image input device in an imaging unit. This can be done in the field of electronic information devices such as digital cameras, image input cameras such as surveillance cameras, scanner devices, facsimile devices, television telephone devices, and mobile phone devices with cameras.

DESCRIPTION OF SYMBOLS 1, 1A CMOS type solid-state image sensor 2 Effective pixel array area 3, 3A Optical black area | region 4 Peripheral circuit area 5, 5A Slit part 5a, 5b Slit (gap)
6 Silicon substrate 7, 13 Insulating film 8a to 8c Metal light shielding film 9 Transistor gate 10 Wiring layer 11 Color filter 12 On-chip lens 90 Electronic information device 91 Solid-state imaging device 92 Memory unit 93 Display unit 94 Communication unit 95 Image output unit

Claims (18)

Above the semiconductor substrate, an effective pixel array area for photoelectrically converting incident light from a subject to be imaged is provided in the central portion, and an imaging signal from the effective pixel array area is provided on the outer peripheral side of the effective pixel array area. In a solid-state imaging device in which an optical black region for performing black level correction is provided, and a peripheral circuit region is provided on the outer peripheral side of the optical black region,
Shielding film is provided to shield incident light to the optical black region and the peripheral circuit region, to all or part of the boundary of the light shielding film in the optical black region and the peripheral circuit region, a slit for opening stress Part is provided,
The slit portion is a solid-state imaging device formed on two opposite sides of the effective pixel array region and the optical black region on the outer peripheral side thereof in a rectangular shape in plan view. Above the semiconductor substrate, an effective pixel array area for photoelectrically converting incident light from a subject to be imaged is provided in the central portion, and an imaging signal from the effective pixel array area is provided on the outer peripheral side of the effective pixel array area. In a solid-state imaging device in which an optical black region for performing black level correction is provided, and a peripheral circuit region is provided on the outer peripheral side of the optical black region,
Shielding film is provided to shield incident light to the optical black region and the peripheral circuit region, to all or part of the boundary of the light shielding film in the optical black region and the peripheral circuit region, a slit for opening stress Part is provided,
The slit portion has an outer periphery of a full shape including a concave shape excluding a square shape or a rectangular shape of at least one corner of the outer periphery from the square shape in plan view of the effective pixel array region and the optical black region on the outer periphery thereof. A solid-state imaging device formed entirely or partially. Above the semiconductor substrate, an effective pixel array area for photoelectrically converting incident light from a subject to be imaged is provided in the central portion, and an imaging signal from the effective pixel array area is provided on the outer peripheral side of the effective pixel array area. A solid-state imaging device in which an optical black region for performing black level correction is provided, and a peripheral circuit region is provided on the outer peripheral side of the optical black region ,
A plurality of photoelectric conversion elements are formed in the semiconductor layer of the semiconductor substrate in the effective pixel array region and the optical black region on the first surface side of the semiconductor substrate, and in the optical black region and the peripheral circuit region A light-shielding film is formed on the second surface side of the semiconductor substrate, and image light is incident from the second surface side in the effective pixel array region and an image is captured by the plurality of photoelectric conversion elements. In the element
The light shielding film is provided to shield incident light to the optical black region and the peripheral circuit region, to all or part of the boundary of the light shielding film in the optical black region and the peripheral circuit region, for releasing stress A slit is provided,
A solid-state imaging device in which the optical black region is provided on the outer peripheral side of at least one side of the effective pixel array region in a plan view, and the slit portion is formed over the outer periphery of the optical black region. Above the semiconductor substrate, an effective pixel array area for photoelectrically converting incident light from a subject to be imaged is provided in the central portion, and an imaging signal from the effective pixel array area is provided on the outer peripheral side of the effective pixel array area. A solid-state imaging device in which an optical black region for performing black level correction is provided, and a peripheral circuit region is provided on the outer peripheral side of the optical black region ,
A plurality of photoelectric conversion elements are formed in the semiconductor layer of the semiconductor substrate in the effective pixel array region and the optical black region on the first surface side of the semiconductor substrate, and in the optical black region and the peripheral circuit region A light-shielding film is formed on the second surface side of the semiconductor substrate, and image light is incident from the second surface side in the effective pixel array region and an image is captured by the plurality of photoelectric conversion elements. In the element
The light shielding film is provided to shield incident light to the optical black region and the peripheral circuit region, to all or part of the boundary of the light shielding film in the optical black region and the peripheral circuit region, for releasing stress A slit is provided,
A solid-state imaging device in which a semiconductor layer of the semiconductor substrate corresponding to the lower portion of the slit is an inactive region in which no active device is disposed.   The slit portion is a buffer region in which stress of the light shielding film in the peripheral circuit region is not transmitted to or hardly transmitted to the light shielding film in the optical black region and the semiconductor layer under the light shielding film. The solid-state image sensor described in 1.   5. The solid-state imaging device according to claim 4, wherein the slit portion is formed over an outer peripheral side of at least one side of a quadrangle in a plan view of the effective pixel array region and the optical black region on the outer peripheral side thereof.   The solid-state imaging device according to claim 6, wherein the slit portion is formed over an outer periphery of a quadrangle in a plan view of the effective pixel array region and the optical black region on the outer peripheral side thereof.   7. The solid-state imaging device according to claim 6, wherein the slit portion is formed on two opposite sides of the effective pixel array region and the optical black region on the outer peripheral side thereof in a rectangular shape in plan view.   The slit portion has an outer periphery of a full shape including a concave shape obtained by removing at least a square shape or a rectangular shape of an outer peripheral corner portion from a rectangular shape in plan view of the effective pixel array region and the optical black region on the outer peripheral side thereof. The solid-state imaging device according to claim 3, wherein the solid-state imaging device is formed in whole or in part.   The solid-state imaging device according to claim 9, wherein a light-shielding film for the optical black region is not provided in at least one corner portion of the optical black region having a quadrangular plan view.   From the rectangular ring-shaped light shielding film in the peripheral circuit region, the optical black region has a plan view outline projecting into a region where at least one corner of the quadrangle is recessed so as to cover the semiconductor substrate. The solid-state imaging device according to claim 9 or 10, wherein a light-shielding film is added to at least one corner side of the inner peripheral four corners.   The solid-state imaging device according to claim 11, wherein the slit portion provided between the optical black region and the peripheral circuit region is formed to surround the outer peripheral side of the optical black region in a ring shape with the same width.   5. The optical black region is provided on an outer peripheral side of at least one side of a square in a plan view of the effective pixel array region, and the slit portion is formed over an outer periphery of the optical black region. The solid-state image sensor described in 1.   The solid-state imaging device according to claim 1, wherein the slit portion is provided continuously or intermittently.   The solid-state imaging device according to claim 1, wherein a semiconductor layer of the semiconductor substrate corresponding to the lower portion of the slit is an inactive region where no active device is disposed.   The said light shielding film is a metal light shielding film, Comprising: Either of aluminum material (Al), tungsten material (W), and titanium material (Ti or TiN) is comprised in any one of Claims 1-4 The solid-state imaging device described. A plurality of photoelectric conversion elements are formed in the semiconductor layer of the semiconductor substrate in the effective pixel array region and the optical black region on the first surface side of the semiconductor substrate, and in the optical black region and the peripheral circuit region The back-illuminated solid-state imaging in which the light-shielding film is formed on the second surface side of the semiconductor substrate, and image light is incident from the second surface side in the effective pixel array region and images are captured by the plurality of photoelectric conversion elements solid-state imaging device according to any one of claims 1 and 2 is an element.   An electronic information device using the solid-state imaging device according to claim 1 as an image input device in an imaging unit.