JP2011082386A - Solid-state imaging element, method for manufacturing the element, and imaging device using the element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate a dark current difference between an effective pixel region and an OB part, and to suppress a parasitic MOS effect in the OB part. <P>SOLUTION: The solid-state imaging element includes a plurality of photodiodes (PDs) formed in a front surface part of a semiconductor substrate, an antireflective film 54 covering the front surface part, and a shade film 55 dividing a region of the front surface part formed with the PDs into an effective pixel region of a center part and a circumferential OB part and covering areas other than individual light reception surfaces of the PDs 42a in the effective pixel region. Parts other than the light reception surfaces of the PDs 42a in the effective pixel region out of the antireflective film 54 in the effective pixel region are removed, the antireflective film 54 on regions corresponding to right reception surfaces of the PDs 42b of the OB part are removed, and a first insulating layer (x) formed between the shade film 55 covering the OB part and the regions corresponding to the light reception parts is formed thicker than a second insulating layer (y) excluding the antireflective film 54 between the light reception surfaces of the PDs 42a in the effective pixel region and an opening end of the shade film 55 facing the light reception surfaces. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device with low dark current noise and stable dark current noise, a method for manufacturing the same, and an imaging apparatus equipped with the solid-state imaging device.

  A solid-state imaging device, for example, a CCD type solid-state imaging device, includes a photodiode (PD: hereinafter also referred to as a pixel), a vertical charge transfer path (VCCD), a horizontal charge transfer path (HCCD), and an output amplifier (FDA: A floating diffusion amplifier (SFA: source follower amplifier) is included.

  FIG. 15 is a schematic diagram of the entire surface of the CCD solid-state imaging device, and illustration of the VCCD, HCCD, and output amplifier is omitted. This solid-state imaging device 1 is provided with a rectangular effective pixel area 2 in the center, and a large number of pixels 3 are arranged and formed in the effective pixel area 2 in a two-dimensional array (in the illustrated example, a square lattice). ing.

  Further, an optical black (OB) portion 4 is provided around the effective pixel region 2, and pixels 5 (see FIG. 16) are arranged and formed in the OB portion 4 in the same arrangement as the effective pixel region 2. ing.

  FIG. 16 is a schematic cross-sectional view taken along the line BB in FIG. 15, and is a schematic cross-sectional view of a pixel at a boundary portion between the effective pixel region 2 and the OB portion 4. Each pixel (PD) 3 in the effective pixel region 2 is formed under each opening 6a of the light shielding film 6 such as a tungsten film, whereas each pixel (PD) 5 in the OB portion 4 is formed from the light shielding film. 6 is configured to detect a black level signal that is not exposed to light.

  In the solid-state imaging device 1, an antireflection film 9 is formed between the light shielding film opening 6 a and the oxide film (gate insulating film) 8 formed on the surface of the semiconductor substrate 7 in order to increase the light receiving sensitivity of each pixel. It is common to do. As the antireflection film 9 formed under the light shielding film 6, a silicon nitride film (SiN) by a low pressure CVD method (LP-CVD method) is generally used.

  However, if the entire surface of the image sensor device is covered with a silicon nitride film formed by LP-CVD, the effect of low-temperature heat treatment (nitrogen diluted hydrogen annealing, sintering) for suppressing dark current generated at the MOS interface may be lost. Are known. The mechanism is considered to be because hydrogen that terminates dangling bonds at the MOS interface cannot pass through the silicon nitride film.

  For this reason, it is common to employ a structure in which a part of each pixel is removed by patterning and etching to provide a path through which hydrogen can reach the MOS interface. And the part which removes the antireflection film is usually a part which is not the light shielding film opening 6a. In the example of FIG. 16, the upper surface portion 11 (here, an insulating oxide film) of the vertical transfer electrode film (polysilicon film) 10 is used.

  The solid-state imaging device 1 is provided with an OB unit 4 that detects a black level for accurately reading a photoelectrically converted signal value. The difference between the pixel 5 in the OB unit 4 and the pixel 3 in the effective pixel region 2 is as follows. It is only the presence or absence of the light shielding film opening 6a. When comparing the dark current of the photodiode (PD) and the vertical charge transfer path (VCCD) of the CCD type solid-state imaging device, the embedded PD has much less dark current than the embedded type VCCD. For this reason, what determines the signal value (dark current noise) of the OB unit 4 can be considered to be mostly VCCD. Therefore, some pixels 5 in the OB portion 4 have a structure in which the photodiode PD is not provided.

  A tungsten film (W, W / TiN, W / TiN / Ti, etc.) having good heat resistance and good coverage is often used for the light shielding film 6 of the CCD solid-state imaging device. Tungsten W is also relatively difficult to pass hydrogen, and titanium (Ti) is known to adsorb hydrogen.

  That is, the pixel 5 in the OB portion is covered with the light-shielding film 6 at a higher rate than the pixel 3 and the nitride film coverage is the same as that of the pixel 3. It becomes narrower and the dangling bond termination at the MOS interface becomes weak, resulting in an increase in dark current. That is, there is a problem that a difference may occur in the dark current between the effective pixel region and the OB portion.

  This problem can be achieved by adopting a structure that ensures a wide (many) path through which hydrogen passes through the OB portion 4.

  Specifically, the portion where the silicon nitride film in the OB portion 4 is removed may be made larger (wider) than the pixel 3 in the effective pixel region 2. However, the silicon nitride film also has an effect of ensuring the withstand voltage between the light shielding film 6 and the polysilicon electrode 10, and if the silicon nitride film in the OB portion is largely removed, the light shielding film 6 and the polysilicon are removed. Another problem may occur that the manufacturing yield of the solid-state imaging device is reduced due to leakage between the electrodes 10.

  By the way, a CCD type solid-state imaging device has a peculiar noise called smear. In order to reduce this smear, it is effective to make the distance (insulating film thickness) between the light shielding film 6 and the silicon substrate 7 as small as possible.

  At present, for example, in a CCD type solid-state imaging device having about 2 μm square pixels, the insulation film thickness between the light shielding film 6 and the silicon substrate 7 is about 100 nm in terms of an electrical insulation film thickness (oxide film capacitance equivalent film thickness). As the pixels become finer, they tend to become even more bookkeeping. Since the gate insulating film thickness of the CCD type solid-state imaging device is about 50 nm, it is equal to the gate insulating film thickness or several times as thin.

  Tungsten, which is a material of the light shielding film 6, is a conductor. In order to avoid the potential of the light shielding film 6 being in a floating state, it is generally fixed to the GND potential or other DC potential.

  As described above, when the insulating film thickness between the light shielding film 6 and the silicon substrate 7 is reduced and the light shielding film potential is fixed, the parasitic MOS effect using the light shielding film 6 as a gate cannot be ignored.

  The portion where the parasitic MOS effect becomes large is the OB portion 4 where the parasitic gate insulating film is thin and the parasitic gate is widely spread. In particular, in order to solve the problem of widening the path through which hydrogen passes, it is considered that a structure in which the silicon nitride film in the region corresponding to the light shielding film opening of the pixel 5 is removed in the OB portion 4 is effective. In this case, since the light shielding film 6 approaches the gate oxide film 8 below the silicon nitride film, the parasitic MOS effect using the light shielding film 6 as a gate is further increased.

  In other words, the parasitic MOS effect is more effective than the effect of expanding the hydrogen path of the OB unit 4 to reduce the dark current, and a new problem arises that the dark current may be increased.

  Further, in the current miniaturized cell and the further miniaturized cell in the future, even if the insulating film is not thinned in the region corresponding to the opening of the pixel 5 of the OB portion 4 as described above, the parasitic MOS In some cases, the effect is significant and dark current is increased. The same applies to the CMOS type solid-state imaging device.

  In addition, as a publicly known example in which a path for a hydrogen path provided in the silicon nitride film is provided in addition to the upper part of the photodiode, there is the following Patent Document 1, in which the antireflection film under the OB portion is narrower than the antireflection film in the effective pixel region As an example, there is Patent Document 2 below.

Japanese Patent Laid-Open No. 10-284709 JP 2007-35993 A

  An object of the present invention is to provide a solid-state imaging having a structure in which the hydrogen path path in the OB portion is secured, the parasitic MOS effect is reduced, the dark current difference between the effective pixel region and the OB portion is small, and the dark current noise is stable. It is an object to provide an element, a manufacturing method thereof, and an imaging apparatus equipped with the solid-state imaging element.

  The solid-state imaging device and the manufacturing method thereof according to the present invention include a plurality of photodiodes arranged in a two-dimensional array on a surface portion of a semiconductor substrate, an antireflection film covering the surface portion, and the photodiode on the surface portion. A solid-state imaging device comprising: a light shielding film that divides a region in which an effective pixel region is formed into a central effective pixel region and an optical black portion around the effective pixel region and covers the effective pixel region other than the individual light receiving surfaces of the photodiodes And a method of manufacturing the same, wherein a portion other than the light receiving surface of the photodiode in the effective pixel region is deleted from the antireflection film of the effective pixel region, and the light receiving surface of the photodiode in the optical black portion The antireflection film on the region corresponding to is formed by removing the antireflection film before covering the region corresponding to the light receiving surface of the optical black portion. The first insulating layer (x) formed between the light-shielding film and the region corresponding to the light-receiving surface has an opening end of the light-shielding film facing the light-receiving surface of the photodiode in the effective pixel region and the light-receiving surface. It is characterized by being formed thicker than the second insulating layer (y) excluding the antireflection film between the two portions.

  In addition, an image pickup apparatus according to the present invention is characterized in that the solid-state image pickup device described above is mounted.

  According to the present invention, since the OB portion can also obtain a sintering effect and the parasitic MOS effect can be reduced, the difference between the dark current in the OB portion and the dark current in the effective pixel region can be suppressed. It is possible to stabilize the dark current noise. For this reason, an imaging device equipped with this solid-state imaging device can capture a high-quality subject image.

It is a functional block block diagram of the imaging device which concerns on one Embodiment of this invention. It is a surface schematic diagram of the CCD type solid-state imaging device shown in FIG. FIG. 3 is a schematic sectional view taken along line III-III in FIG. 2. It is process drawing explaining the solid-state image sensor manufacturing method of embodiment shown in FIG. FIG. 5 is a process diagram following FIG. 4. It is a cross-sectional schematic diagram of the solid-state image sensor of another embodiment of this invention. It is process drawing explaining the manufacturing method of the solid-state image sensor shown in FIG. FIG. 8 is a process diagram following FIG. 7. It is a cross-sectional schematic diagram of the solid-state image sensor of another embodiment of this invention. It is a principal part enlarged surface schematic diagram of the solid-state image sensor shown in FIG. It is process drawing explaining the manufacturing method of the solid-state image sensor shown in FIG. It is a cross-sectional schematic diagram of the solid-state image sensor of another embodiment of this invention. It is a principal part enlarged surface schematic diagram of the solid-state image sensor shown in FIG. It is process drawing explaining the manufacturing method of the solid-state image sensor shown in FIG. It is a surface schematic diagram of the conventional solid-state image sensor. FIG. 16 is a schematic cross-sectional view taken along line BB in FIG. 15.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a functional configuration diagram of an imaging apparatus (in this example, a digital still camera) 20 according to an embodiment of the present invention. The imaging apparatus 20 includes an imaging unit 21, an analog signal processing unit 22 that performs analog processing such as automatic gain adjustment (AGC) and correlated double sampling processing on analog image data output from the imaging unit 21, and analog signal processing. An analog / digital conversion unit (A / D) 23 that converts analog image data output from the unit 22 into digital image data, and an A / D 23 and an analog signal processing unit 22 in accordance with instructions from a system control unit (CPU) 29 described later. , A drive unit (including a timing generator TG) 24 that controls the drive of the imaging unit 21 and a flashlight 25 that emits light in response to an instruction from the CPU 29.

  The imaging unit 21 collects light from a subject, a diaphragm for condensing light passing through the optical lens system 21a, a mechanical shutter 21b, and the optical lens system 21a, and is condensed by the diaphragm. A CCD type solid-state imaging device 35 that receives light and outputs captured image data (analog image data).

  The imaging apparatus 20 of the present embodiment further includes a digital signal processing unit 26 that takes in digital image data output from the A / D 23 and performs interpolation processing, white balance correction, RGB / YC conversion processing, and the like, and image data as JPEG format or the like. A compression / decompression processing unit 27 that compresses or reversely decompresses the image data, a liquid crystal display unit 28 that is provided on the back side of the camera and displays a menu screen, a through image, and a captured image, and an overall control of the entire imaging apparatus. A system control unit (CPU) 29, an internal memory 30 such as a frame memory, and a media interface (I / F) unit 31 that performs interface processing between a recording medium 32 that stores JPEG image data and the like. The system controller 29 includes an operation unit 3 for inputting instructions from the user. There has been connected.

  FIG. 2 is a schematic view of the surface of the CCD solid-state imaging device 35 shown in FIG. A plurality of pixels (photodiodes: PD) 42 are arrayed on the surface of the semiconductor substrate 41 in a two-dimensional array form, in the illustrated example, in a square lattice form.

  A vertical charge transfer path (VCCD) 43 is formed for each pixel column, a horizontal charge transfer path (HCCD) 44 is formed along the transfer direction end of each vertical charge transfer path 43, and an output end of the horizontal charge transfer path 44. An amplifier 45 is formed in the part. Each pixel 42 and the vertical charge transfer path 43 are connected by a read gate portion 43 '.

  The region where the photodiode 42 is formed is divided into an effective pixel region 47 and an optical black (OB) portion 48 provided so as to surround the four circumferences of the effective pixel region 47. The difference between the effective pixel region 47 and the OB portion 48 is that each pixel 42 in the OB portion 48 is covered with a light shielding film, whereas the light shielding film on the light receiving surface of each pixel 42 in the effective pixel region 47 has an opening. Is a point provided. Hereinafter, the code of the pixel in the effective pixel area 47 is “42a”, and the code of the pixel in the OB unit 48 is “42b”.

  3 is a schematic cross-sectional view taken along the line III-III of FIG. 2, and is a schematic cross-sectional view of the pixel 42a and the pixel 42b straddling the boundary line between the effective pixel region 47 and the OB portion 48.

  A p-well layer 51 is formed on the surface portion of the n-type semiconductor substrate 41, and n regions 42a and 42b for forming pixels (photodiodes) are formed therein. Also, an n-region buried channel 43a constituting the vertical charge transfer path 43 is formed between the pixels.

  A gate oxide film 52 is formed on the outermost surface of the semiconductor substrate 41 (= the outermost surface of the p well layer 51), and a vertical transfer electrode made of a polysilicon film is formed on the buried channel 43a sandwiching the gate oxide film 52 therebetween. A film 43b is formed. The vertical charge transfer path 43 includes a buried channel 43a, a gate oxide film 52, and a vertical transfer electrode film 43b (and 43c described later).

  A silicon nitride film 54 as an antireflection film is laminated on the gate oxide film 52 and the polysilicon film 43b. In order to obtain a sintering effect, if the silicon nitride film 54 is a pixel 42a in the effective pixel region, the transfer electrode film 43b of the adjacent vertical charge transfer path 43 is deleted to form a hydrogen path. In the case of the pixel 42b in the OB portion, the silicon nitride film 54 on the photodiode 42b is cut to form a hydrogen passage. Thereby, the dark current difference due to the sintering effect between the effective pixel region and the OB portion is suppressed.

  On the silicon nitride film 54, an interlayer insulating film 53 and a light shielding film 55 made of tungsten W are stacked. If the pixel 42a is in the effective pixel region, a light shielding film opening 55a is provided thereon. In the case of the pixel 42b in the OB portion, the light shielding film opening is not provided, and the light receiving surface is covered with the light shielding film 55b.

  In the solid-state imaging device 35 of the present embodiment, the thickness x of the insulating layer 56 provided below the portion of the light shielding film 55b that covers the light receiving surface of the pixel 42b is the total thickness of the gate oxide film 52 and the interlayer insulating film 53. Thicker than y. Thereby, the parasitic MOS effect is reduced and an increase in dark current is suppressed. Here, the film thickness means an electrical film thickness (oxide film equivalent film thickness) rather than a physical film thickness, and z represents a gate oxide film 52, an interlayer insulating film 53, and a nitride film 54. X is at least thicker than y, preferably thicker than z.

  If the light shielding film 55 is laminated immediately after the silicon nitride film 54 is removed by etching, the distance between the light shielding film 55b and the semiconductor substrate 41 becomes the total thickness of the gate oxide film 52 and the interlayer insulating film 53 and is close. As a result, the parasitic MOS effect due to the parasitic gate of the light shielding film 55b is increased. However, in this embodiment, since the insulating layer 56 is formed thick, the parasitic MOS effect can be suppressed.

  Thereby, in the present embodiment, the dark current difference between the effective pixel region and the OB portion is reduced, the sintering effect can be obtained, and the dark current noise is also stabilized. Hereinafter, a method for manufacturing a solid-state imaging device that realizes the structure of the embodiment of FIG. 3 will be described.

  4 and 5 are manufacturing process diagrams of the solid-state imaging device having the structure of the embodiment of FIG. In step (a), after forming the gate oxide film 52, the vertical transfer electrode 43b, and the interlayer insulating film 58, a silicon nitride film (SiN) 54 is deposited by 30 nm by, for example, LP-CVD.

  In the next step (b), the resist 59 is patterned using a photomask, and the resist is removed from the portion where the silicon nitride film 54 in the OB portion is removed for the sintering effect (above the pixel 42b in FIG. 3). except.

  In step (c), for example, the silicon nitride film 54 located above the pixel 42b is etched away by chemical dry etching (CDE) to form a hole 54a, and the remaining resist is also removed.

  In the next step (d), for example, SiO 60 is deposited to a thickness of 100 nm by the LP-CVD method. Then, in the next step (e) of FIG. 5, the resist 61 is patterned using a photomask, and the resist 61 is deposited above the hole 54 a of the silicon nitride film 54.

  In the next step (f), when the SiO 60 is removed by reactive ion etching (RIE), for example, the SiO 60 below the resist 61, that is, above the hole 54a remains.

  In the next step (g), the resist 62 is patterned using a photomask, and the resist is removed from a location (above the vertical transfer electrode 43b) where the silicon nitride film 54 in the effective pixel region is removed for the sintering effect. except.

  Then, in the next step (h), the silicon nitride film 54 is removed by etching by the CDE method to form the hole 54b, the remaining resist is also removed, and in the final step (i), the light shielding film 55 is formed. For example, 50 nm of SiO63 is deposited by LP-CVD, 200 nm of tungsten is deposited by physical vapor deposition (PVD), resist patterning is performed using a photomask, and openings 55a are formed by, for example, RIE. The tungsten film may be removed and the residual resist may be removed. As a result, the oxide film thickness at the hole 54 b becomes thicker than the total film thickness of the gate oxide film 52 and the interlayer insulating film 53.

  In the present embodiment, two types of holes 54a and 54b are formed in the silicon nitride film 54 used as an antireflection film, but these are formed in separate steps. Of course, it is possible to open the holes 54a and 54b in one step. However, changing the structure of the OB portion greatly affects the optical characteristics and changes the shape of the pixel portion, which causes a dark current difference between the effective image region and the OB portion. In the embodiment, as a separate process, a process in which the pixel structure of the OB portion does not change from the pixel structure of the effective pixel region is used.

  FIG. 6 is a schematic cross-sectional view of an alternative embodiment to FIG. In the present embodiment, another silicon nitride film 66 is formed via an oxide film 65 at a location where the silicon nitride film 54 located above the pixel 42b in the OB portion is removed to form a hole 54a, and a light shielding film thereon. 3 is different from the embodiment of FIG. 3 in that the parasitic MOS effect is reduced by separating the distance between 55b and the semiconductor substrate 41. Although the silicon nitride film 66 does not allow hydrogen to pass therethrough, since the oxide film 65 between the silicon nitride film 54 serves as a path for the hydrogen passage, a sintering effect can be obtained.

  7 and 8 are process explanatory diagrams of the manufacturing method of the solid-state imaging device of FIG. Step (a) in FIG. 7 is the same as step (a) in FIG. In the next step (b), patterning of the resist 67 is performed using a photomask to determine the locations where holes 54a and 54b are to be formed in the silicon nitride film 54. Then, in the next step (c), when the silicon nitride film 54 is removed by etching, for example, by the CDE method, and the residual resist is also removed, holes 54a and 54b serving as hydrogen paths are formed at a time.

  In the next step (d), for example, SiO 65 is deposited by 50 nm by LP-CVD, and further, a silicon nitride film 66 is deposited by 30 nm by LP-CVD.

  In the next step (e) shown in FIG. 8, a photomask is used to pattern the resist 68 at a position above the pixel 42b, that is, above the hole 54a. In the next step (f), the hole is formed by, for example, the CDE method. The remaining portion of the silicon nitride film 66 is removed by etching while leaving the silicon nitride film 66 above the position 54a, and the remaining resist is also removed.

  In the last step (g), the light shielding film 55 is formed on the SiO 69 in the same manner as in the step (i) of FIG.

  According to the present embodiment, fine dimension control (for example, dimension control of the register 61 in FIG. 5) at the surface irregularities formed in the middle of manufacturing the imaging device is not required, so the holes 54a and 54b are formed at a time. It is possible to manufacture the solid-state imaging device more stably.

  FIG. 9 is a schematic cross-sectional view of a solid-state imaging device according to another embodiment instead of FIG. In the solid-state imaging device of the present embodiment, the antireflection film (silicon nitride film) 54 in the effective pixel region is left, and all the silicon nitride film in the OB portion is deleted. Then, a polysilicon film 43 c ′ is also formed in the space between the polysilicon films 43 b above the pixels 42 b in the OB portion, and all of the polysilicon film 43 c ′ is covered with the light shielding film 55.

  FIG. 10 is a top view of four pixels at the position shown in the cross section in FIG. On the buried channel 43a extending in the vertical direction, vertical transfer electrodes 43b and 43c having a single layer film structure are alternately laid. In the example shown in the drawing, the vertical transfer electrode 43b extends to the vicinity of the adjacent photodiode (PD). Thus, a read gate portion 43 ′ is formed and also serves as a read electrode.

  Since a high-voltage read pulse is applied to the read electrode, in the present embodiment, a polysilicon film 43c ′ that covers the upper position of the pixel 42b in the OB portion is provided so as to integrally extend from the other vertical transfer electrode 43c. By this polysilicon film 43c ′, the semiconductor substrate 41 and the light shielding film 55 are separated from each other to reduce the parasitic MOS effect. However, the polysilicon film 43c 'may be an isolated electrode film independent of the transfer electrode film, and the potential thereof may be a floating potential.

  FIG. 11 is a manufacturing process diagram of the solid-state imaging device of the embodiment shown in FIG. Similar to a well-known manufacturing method of a normal CCD type solid-state imaging device, a photodiode (PD) 42a, 42b or a VCCD n region 43a is formed in a semiconductor substrate, and then a gate insulating film 52 or transfer electrode films 43b, 43c. ', A transfer electrode insulating film 71 is formed, and in the next step (a), a silicon nitride film 54 is deposited by 30 nm by, for example, LP-CVD.

  In the next step (b), the resist 72 is patterned using a photomask to prepare for removing the silicon nitride film 54 on the polysilicon films 43b and 43c '.

  In the next step (c), the silicon nitride film 54 is removed by etching, for example, by the CDE method, and the residual resist is further removed. Then, in step (d), SiO 73 is deposited to 50 nm by LP-CVD, and tungsten film 55 is deposited to 200 nm by PVD, and resist 74 is patterned using a photomask to form a light shielding film opening on pixel 42a. Prepare to open.

  In the next step (e), the portion of the light shielding film (tungsten film) 55 on the pixel 42a is removed by etching, for example, by RIE, and the residual resist is removed.

  FIG. 12 is a schematic cross-sectional view of an alternative embodiment to FIG. In the embodiment of FIG. 9, the pixel 42b of the OB portion is covered with the polysilicon film 43c ′ having the same area as the pixel 42b. However, in the present embodiment, as shown in FIG. The difference is that a rectangular hole 43d is provided at the center of '.

  FIG. 14 is a manufacturing process diagram of the solid-state imaging device of FIG. 12. The content of the process is almost the same as that of FIG. 11, and can be realized by changing the resist patterning pattern.

  After forming photodiodes (PD) 42a, 42b and VCCD n-region 43a in the semiconductor substrate, gate electrode 52, transfer electrode film 43b and transfer electrode film 43c 'in which holes 43d are formed, and transfer electrode insulating film 71 is formed.

  Then, in the next step (a), a silicon nitride film 54 is deposited to a thickness of 30 nm by, for example, LP-CVD. In the next step (b), the resist 72 is patterned using a photomask, and silicon on the polysilicon film 43b is formed. Preparation for removing the nitride film 54 is performed.

  In the next step (c), the silicon nitride film 54 is removed by etching, for example, by the CDE method, and the residual resist is further removed. Then, in step (d), SiO 73 is deposited to 50 nm by LP-CVD, and tungsten film 55 is deposited to 200 nm by PVD, and resist 74 is patterned using a photomask to form a light shielding film opening on pixel 42a. Prepare to open.

  In the next step (e), the portion of the light shielding film (tungsten film) 55 on the pixel 42a is removed by etching, for example, by RIE, and the residual resist is removed.

  In the present embodiment, compared to the embodiment shown in FIG. 9, the distance between the light shielding film 55 and the surface of the semiconductor substrate 41 at the hole 43d portion due to the relationship in which the hole 43d is opened in the polysilicon film 43c ′. However, if the average distance in the area of the pixel 42d is considered, a sufficient distance can be obtained and the parasitic MOS effect can be reduced.

  The silicon nitride film 54 remaining in the hole 43d may not be present, and may be removed during etching. In this case, the distance between the light shielding film 55 and the surface of the semiconductor substrate is further shortened in the hole 43d, but the average distance per pixel area is still increased, so that the parasitic MOS effect is reduced.

  In each of the above-described embodiments, the CCD solid-state imaging device has been described as an example. However, the present invention is not limited to the CCD type. Even in the CMOS type solid-state imaging device, the distance between the surface of the semiconductor substrate and the light shielding film thereabove (sometimes also used as electrode wiring) has become shorter as the pixels become smaller. It is thought that the effect of current increase becomes significant. Therefore, the present invention that achieves a balance between the sintering effect by removing the silicon nitride film and the parasitic MOS effect based on the proximity of the light shielding film to the surface of the semiconductor substrate is effective.

  Further, although the embodiment in which the photodiode (n region) 42b is provided in the OB portion has been described, the above-described embodiment can be applied as it is even when the photodiode 42b is not provided in the OB portion. The case where the photodiode 42b is not provided is considered to be more affected by the parasitic MOS than the case where the photodiode 42b is provided. Therefore, the embodiment described above is applied to the case where the photodiode 42b is not provided in the OB portion. As a result, the parasitic MOS effect can be reduced.

  As described above, the solid-state imaging device and the manufacturing method thereof according to the embodiment include a plurality of photodiodes arranged in a two-dimensional array on the surface portion of the semiconductor substrate, the antireflection film covering the surface portion, A light shielding film that divides a region where the photodiode is formed on the surface portion into an effective pixel region at a central portion and an optical black portion around the effective pixel region and covers other than the individual light receiving surfaces of the photodiode in the effective pixel region In the solid-state imaging device, a portion other than the light receiving surface of the photodiode in the effective pixel region is deleted from the antireflection film of the effective pixel region, and the light receiving surface of the photodiode in the optical black portion The antireflection film on the region corresponding to is formed by deleting the region corresponding to the light receiving surface of the optical black portion. A first insulating layer (x) formed between the light-shielding film and a region corresponding to the light-receiving surface of the light-shielding film facing the light-receiving surface of the photodiode and the light-receiving surface in the effective pixel region; It is characterized by being formed thicker than the second insulating layer (y) excluding the antireflection film between the opening ends.

  Further, the solid-state imaging device and the manufacturing method thereof according to the embodiment are characterized in that the n region constituting the photodiode in the optical black portion is not formed.

  In the solid-state imaging device and the manufacturing method thereof according to the embodiment, the layer thickness of the first insulating layer and the second insulating layer is a layer thickness in terms of oxide film capacitance.

  Further, the solid-state imaging device and the manufacturing method thereof according to the embodiment are characterized in that the first insulating layer has a laminated structure of a plurality of insulating layers.

  Further, the solid-state imaging device and the manufacturing method thereof according to the embodiment are characterized in that an intermediate layer of the stacked structure of the first insulating layers is formed of a polysilicon film.

  In addition, the solid-state imaging device and the manufacturing method thereof according to the embodiment are characterized in that the solid-state imaging device is a CCD type and the polysilicon film is a transfer electrode film not serving as a readout electrode.

  In the solid-state imaging device and the manufacturing method thereof according to the embodiment, the polysilicon film is a floating electrode film.

  Further, the solid-state imaging device and the manufacturing method thereof according to the embodiment are characterized in that an average thickness of the first insulating layer with respect to a light receiving surface area of the photodiode is thicker than that of the second insulating layer.

  Further, an imaging apparatus according to the embodiment is characterized by mounting any one of the solid-state imaging elements described above.

  According to the above embodiment, since the OB portion can also obtain a sintering effect and reduce the parasitic MOS effect, the difference between the dark current in the OB portion and the dark current in the effective pixel region can be suppressed. It becomes possible to stabilize the dark current noise. For this reason, an image pickup apparatus equipped with this solid-state image pickup device can pick up a high-quality subject image.

  The solid-state imaging device according to the present invention eliminates the difference in dark current between the effective pixel region and the OB portion, and further, the parasitic MOS effect is reduced to reduce the dark current. Therefore, the digital still camera that picks up a high-quality subject image It is useful when applied to general imaging devices such as digital cameras, digital video cameras, mobile phones with cameras, electronic devices with cameras such as PDAs and notebook computers, and endoscopes.

35 Solid-state image sensor 41 Semiconductor substrate 42 Pixel (photodiode: PD)
42a Effective pixel region pixel (photodiode: PD)
42b Optical Black (OB) Pixel (Photodiode: PD)
43 Vertical Charge Transfer Path (VCCD)
43 'read gate portion 43a buried channel 43b polysilicon film (vertical transfer electrode also serving as read electrode)
43c Polysilicon film (vertical transfer path electrode different from readout electrode)
43c ′ Polysilicon film 43d covering the pixel in the OB portion Hole 44 of the polysilicon film Horizontal charge transfer path (HCCD)
47 Effective pixel region 48 OB portion 51 p well layer 52 on semiconductor substrate surface portion gate insulating film 54 silicon nitride film (antireflection film)
55 Light-shielding film (tungsten film)
55a Light shielding film opening 56 Insulating layer

Claims (17)

  A plurality of photodiodes arrayed in a two-dimensional array on the surface portion of the semiconductor substrate, an antireflection film covering the surface portion, and an area where the photodiodes are formed on the surface portion as an effective pixel region at a central portion And a light-shielding film that covers the effective pixel region and the optical black portion around the effective pixel region, and covers a portion other than each light receiving surface of the photodiode in the effective pixel region, wherein the antireflection of the effective pixel region A portion of the film other than the light receiving surface of the photodiode in the effective pixel region is deleted, and the antireflection film on a region corresponding to the light receiving surface of the photodiode in the optical black portion is deleted. A first edge formed between the light shielding film covering the region corresponding to the light receiving surface of the optical black portion and the region corresponding to the light receiving surface. The layer (x) is a second insulating layer (y) excluding the antireflection film between the light receiving surface of the photodiode in the effective pixel region and the opening end of the light shielding film facing the light receiving surface. A solid-state imaging device formed thick.   2. The solid-state imaging device according to claim 1, wherein an n region constituting the photodiode of the optical black portion is not formed.   3. The solid-state imaging device according to claim 1, wherein the first insulating layer and the second insulating layer have a thickness equivalent to an oxide film capacitance. 4.   4. The solid-state imaging device according to claim 1, wherein the first insulating layer has a stacked structure of a plurality of insulating layers. 5.   5. The solid-state imaging device according to claim 4, wherein an intermediate layer of the laminated structure of the first insulating layers is formed of a polysilicon film.   6. The solid-state imaging device according to claim 5, wherein the solid-state imaging device is a CCD type, and the polysilicon film is a transfer electrode film not serving as a readout electrode.   The solid-state imaging device according to claim 5, wherein the polysilicon film is a floating electrode film.   8. The solid-state imaging device according to claim 1, wherein an average thickness of the first insulating layer with respect to a light receiving surface area of the photodiode is thicker than that of the second insulating layer. .   A plurality of photodiodes arrayed in a two-dimensional array on the surface portion of the semiconductor substrate, an antireflection film covering the surface portion, and an area where the photodiodes are formed on the surface portion as an effective pixel region at a central portion And a light-shielding film that covers the effective pixel region and the optical black portion around the effective pixel region, and covers a portion other than each light receiving surface of the photodiode in the effective pixel region. Of the antireflection film, a portion other than the light receiving surface of the photodiode in the effective pixel region is deleted, and the antireflection film on a region corresponding to the light receiving surface of the photodiode in the optical black portion is deleted. Formed between the light-shielding film covering the region corresponding to the light-receiving surface of the optical black portion and the region corresponding to the light-receiving surface. The first insulating layer (x) is a second insulating layer excluding the antireflection film between the light receiving surface of the photodiode in the effective pixel region and the opening end of the light shielding film facing the light receiving surface. (Y) A method of manufacturing a solid-state imaging device formed thicker.   The method for manufacturing a solid-state imaging device according to claim 9, wherein an n region constituting the photodiode of the optical black portion is not formed.   11. The method of manufacturing a solid-state imaging device according to claim 9, wherein the first insulating layer and the second insulating layer have a thickness equivalent to an oxide film capacitance. Method.   12. The method for manufacturing a solid-state imaging device according to claim 9, wherein the first insulating layer has a laminated structure of a plurality of insulating layers.   13. The method for manufacturing a solid-state imaging device according to claim 12, wherein an intermediate layer of the laminated structure of the first insulating layers is formed of a polysilicon film.   14. The method of manufacturing a solid-state imaging device according to claim 13, wherein the solid-state imaging device is a CCD type, and the polysilicon film is a transfer electrode film not serving as a readout electrode.   14. The method of manufacturing a solid-state imaging device according to claim 13, wherein the polysilicon film is a floating electrode film.   16. The method of manufacturing a solid-state imaging device according to claim 9, wherein an average thickness of the first insulating layer with respect to a light receiving surface area of the photodiode is thicker than that of the second insulating layer. Manufacturing method of solid-state image sensor.   An imaging device equipped with the solid-state imaging device according to claim 1.

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