JP2011258598A - Solid-state image pickup element, method of manufacturing the same, and image pickup apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid-state image pickup element capable of achieving a stable black level, and also to provide an image pickup apparatus equipped with the solid-sate image pickup element.SOLUTION: A pixel part includes a light receiving region for receiving incident light, and an optical black region 2b where the incident light is shielded by a light shielding film 18, and a photosensor 30 is made to have the same constitution in the light receiving region and the optical black region 2b. In the optical black region 2b, a distance d between a reading electrode 39a and the photosensor 30 is made to be a distance in which electrical charge is not read from the photosensor 30 when a read out voltage is applied to the reading electrode 39a.

Description

The present invention relates to a solid-state imaging device, a manufacturing method thereof, and an imaging device, and in particular, a CCD (Charge-Coupled Device) type solid-state imaging device having an OPB (optical black) region, a manufacturing method thereof, and an imaging device. It is about.

  Conventionally, a solid-state imaging device such as a CCD or a CMOS has been widely used as an imaging device for an imaging device such as a digital video camera or a digital camera. Since the basic structure of these solid-state imaging devices is a semiconductor, dark current noise inevitably occurs due to thermal charge excitation that occurs inside the semiconductor. Therefore, in order to eliminate the influence of dark current noise, a configuration in which a light-shielded optical black (Optical Black) region is provided adjacent to the light receiving region and a signal transferred from the vertical transfer register in this region is used as a reference for the black level. Used (see, for example, Patent Documents 1 and 2).

The light receiving area and the optical black area are different from the light guiding structure for efficiently guiding incident light to the photosensor and the light shielding structure for blocking the incident light from reaching the photosensor. The register was composed of the same semiconductor structure. For example, a CCD solid-state imaging device called a HAD sensor (Hole Accumulation Diode Sensor) has a P ⁺ NPN junction photosensor formed on an N-type silicon substrate in both a light receiving region and an optical optical black region. The same applies to the vertical transfer register. For example, a vertical transfer register having a CCD structure in which readout electrodes for reading out charges of a photosensor and transfer electrodes for transferring charges are alternately arranged has the same structure.

JP 2007-305675 A JP 2009-164247 A

  However, in the conventional solid-state imaging device as described above, leaked light that enters the gap between the light shielding film and the silicon substrate and enters multiple reflections enters the photo sensor in the optical black region, undergoes photoelectric conversion, and the black level fluctuates. There was a thing. In particular, this problem becomes prominent when shooting with a large amount of light such as in the long exposure mode.

  Therefore, it is considered that the optical black region photosensor can solve this problem by adopting a configuration in which only the P-type diffusion layer is formed without forming the N-type diffusion layer having the charge accumulation function. However, as a result of diligent research on this configuration, the following problems occurred.

  Since the photo sensor in the optical black region does not have the N-type diffusion layer, charges cannot be accumulated like the photo sensor in the light-receiving region having the N-type diffusion layer. Therefore, as shown in FIG. 6, when a high read voltage is applied to the read electrode and breakdown occurs, electrons overflow from the P-type diffusion layer beyond the channel stop and flow into the adjacent vertical transfer register. Vary the black level. For this reason, the signal level of the light receiving area has sunk, and a phenomenon has been found in which white floating occurs in the upper part of the image as shown in FIG. That is, the optical black region has a problem that the tolerance to breakdown is lower than that of the light receiving region, and the black level may fluctuate.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a solid-state imaging device capable of realizing a stable black level and an imaging device including the same.

  In order to achieve the above object, the invention described in claim 1 includes a plurality of two-dimensionally arranged photosensors, a read electrode for reading out charges from the photosensor, a transfer electrode for transferring the read charges, A pixel unit having a vertical transfer register provided for each vertical column of the photosensor, and a horizontal transfer register that horizontally transfers charges transferred from the vertical transfer register, the pixel unit including incident light A light-receiving region that receives light and an optical black region in which the incident light is shielded by a light-shielding film, and the photosensor has the same configuration in the light-receiving region and the optical black region, and in the optical black region, The distance between the readout electrode and the photosensor is the distance between the photosensor when a readout voltage is applied to the readout electrode. Charges to a solid state imaging device has a distance that is not read out.

  According to a second aspect of the present invention, in the solid-state imaging device according to the first aspect, the width of the readout electrode in the optical black region is made narrower than the width of the readout electrode in the light receiving region. The distance between the electrode and the photosensor was a distance at which no charge was read from the photosensor when a read voltage was applied to the read electrode.

  The invention according to claim 3 includes a solid-state image sensor, and the solid-state image sensor includes a plurality of two-dimensionally arranged photosensors, a read electrode for reading charges from the photosensors, and a read charge. A transfer electrode, a pixel unit having a vertical transfer register provided for each vertical column of the photosensor, and a horizontal transfer register that horizontally transfers charges transferred from the vertical transfer register, The pixel portion includes a light receiving region that receives incident light and an optical black region in which the incident light is shielded by a light shielding film, and the photosensors have the same configuration in the light receiving region and the optical black region. In the optical black region, the distance between the readout electrode and the photosensor is determined by applying a readout voltage to the readout electrode. Charge from the photosensor to the imaging device that has a distance that is read.

  According to a fourth aspect of the present invention, there is provided a step of forming a first conductivity type well region in a semiconductor substrate, a step of forming a transfer channel in a vertical transfer register formation region of the well region, Forming a second conductivity type semiconductor region in the photosensor formation region; and forming a first conductivity type first semiconductor region in the well region between the transfer channel and the second conductivity type semiconductor region. Forming a read electrode for reading out charges from the photosensor formed in the photosensor formation region on the transfer channel via an insulating film, and the second conductivity type between the read electrodes. Forming a first conductive type second semiconductor region having an impurity concentration higher than that of the first semiconductor region on the semiconductor region and above the first semiconductor region; Forming a light shielding film on the semiconductor substrate including the transmitting electrode via an insulating film, and the photosensor includes the second conductive type semiconductor region and the second semiconductor region. The solid-state imaging device manufacturing method is configured such that the distance between the readout electrode and the photosensor is such that no charge is read from the photosensor when a readout voltage is applied to the readout electrode.

  According to the present invention, it is possible to prevent the problem of white floating by suppressing the breakdown of the optical black region and the fluctuation of the black level during photographing with a large amount of light, thereby realizing a stable black level.

1 is a schematic configuration diagram of an imaging apparatus having a CCD solid-state imaging device according to an embodiment of the present invention. It is a figure which shows arrangement | positioning of a reading electrode, a transfer electrode, and a photosensor. It is sectional drawing of the II-II arrow added in FIG. It is sectional drawing of the III-III arrow added in FIG. It is a figure which shows the manufacturing method of the solid-state image sensor which concerns on one Embodiment of this invention. It is a figure which shows the manufacturing method of the solid-state image sensor which concerns on one Embodiment of this invention. It is a figure which shows the manufacturing method of the solid-state image sensor which concerns on one Embodiment of this invention. It is a figure which shows the manufacturing method of the solid-state image sensor which concerns on one Embodiment of this invention. It is a figure which shows the manufacturing method of the solid-state image sensor which concerns on one Embodiment of this invention. It is a figure which shows the manufacturing method of the solid-state image sensor which concerns on one Embodiment of this invention. It is a figure which shows the manufacturing method of the solid-state image sensor which concerns on one Embodiment of this invention. It is a figure which shows the manufacturing method of the solid-state image sensor which concerns on one Embodiment of this invention. It is a figure for demonstrating the conventional problem. It is a figure for demonstrating the conventional problem.

Hereinafter, modes for carrying out the invention (hereinafter referred to as “embodiments”) will be described with reference to the drawings. The description will be given in the following order.
1. 1. Configuration of an imaging device provided with a solid-state imaging device 2. Configuration of light receiving region and optical black region in solid-state imaging device Manufacturing method of solid-state imaging device

[1. Configuration of imaging device equipped with solid-state imaging device]
First, the configuration of an imaging device including a solid-state imaging device according to the present embodiment will be described. FIG. 1 is a schematic configuration diagram of an imaging device A in the present embodiment. The imaging device A of this embodiment is a digital still camera called a so-called digital camera. Note that the imaging device A is not limited to a digital still camera, and may be a digital video camera or a camera unit built in a mobile phone or the like.

  FIG. 1 shows a CCD solid-state imaging device 1 for imaging in the imaging device A, and a timing generator 6 that generates a driving signal for driving the solid-state imaging device 1 at a predetermined timing. In addition, the imaging device A includes a power supply unit such as a battery, a storage unit that stores an image data signal generated by imaging, and a control unit that controls the entire imaging device A. The circuits constituting these are shown as separate circuits (chips other than the solid-state imaging device 1) in this figure, but may be provided on the same chip or may be divided into several chips.

  The solid-state imaging device 1 is an interline transfer type (IT type) imaging device, and is based on an N-type silicon substrate 10 which is a semiconductor substrate, and includes a pixel unit 2, a horizontal transfer output unit 4, and a processing circuit 5. Etc. The pixel unit 2 includes a light receiving area 2a and an optical black area 2b. The light receiving area 2a is a light receiving area that receives incident light, and is generally called an imaging area that receives light from a subject. The optical black region 2b is a region where incident light is blocked by the light shielding film. The horizontal transfer output unit 4 horizontally transfers the charges transferred from these areas 2a and 2b, converts them into voltage signals, and outputs them. The signal output from the horizontal transfer output unit 4 is processed by the processing circuit 5. In the optical black region 2b and the horizontal transfer output unit 4, a light shielding film 18 is formed as shown by hatching.

  The light receiving region 2a is provided for each of the plurality of first photosensors 20 arranged two-dimensionally, and on the side of the first photosensor 20 (left side in the configuration example of FIG. 1) for each vertical column of the first photosensors 20. And a first vertical transfer register 25 having a CCD structure. That is, the solid-state imaging device 1 is basically configured with a pixel structure in which the first photosensors 20 are two-dimensionally arranged in a matrix in the light receiving region 2a of the N-type silicon substrate 10. The first photosensor 20 is composed of a photodiode. In FIG. 1, hatching is omitted in order to avoid complication of the drawing, but the first vertical transfer register 25 is covered with the light shielding film 18 like the horizontal transfer output unit 4 and the like, and the vertical transfer clock Driven by Vφ1 to Vφ8.

  As shown in FIG. 2, in the first vertical transfer register 25, read electrodes 29a and transfer electrodes 29b are alternately and continuously arranged, and each of the four read electrodes 29a and the transfer electrodes 29b is set as one set. , 8-phase vertical transfer clocks Vφ1 to Vφ8 are applied. Note that V1 to V8 in FIG. 2 mean the types of vertical transfer clocks Vφ1 to Vφ8 applied to the electrodes 29a and 29b. For example, the vertical transfer clock Vφ1 is applied to the read electrode 29a of V1, the vertical transfer clock Vφ5 is applied to the read electrode 29a of V5, and the vertical transfer clock Vφ8 is applied to the transfer electrode 29b of V8. Reading of signal charges from the first photosensor 20 is performed by applying a high voltage to the read electrodes 29a of V1, V3, V5, and V7. In the transfer of the read signal charges, the signal charges are transferred to the horizontal transfer output unit 4 by applying vertical transfer clocks Vφ1 to Vφ8 to the electrodes 29a and 29b of V1 to V8.

  The optical black region 2b includes a plurality of second photosensors 30 that are two-dimensionally arranged adjacent to the light receiving region 2a, and a CCD provided for each vertical column of the second photosensors 30 on the side of the second photosensor 30. And a second vertical transfer register 35 having a structure. In the optical black region 2 b, the entire second photosensor 30 and the second vertical transfer register 35 are covered with the light shielding film 18, so that incident light does not enter the second photosensor 30. In the second vertical transfer register 35, the read electrodes 39a and the transfer electrodes 39b are alternately and continuously arranged. Like the first vertical transfer register 25, the read voltage and the transfer voltage are generated by the vertical transfer clocks Vφ1 to Vφ8. Is applied and driven. The second photosensor 30 is composed of a photodiode and has the same configuration as the first photosensor 20.

  The horizontal transfer output unit 4 includes a horizontal transfer register 45 having a CCD structure to which the first vertical transfer registers 25, 25... In the light receiving area 2a and the second vertical transfer registers 35, 35. . The horizontal transfer register 45 is configured to horizontally transfer signal charges transferred from the first vertical transfer registers 35 by a known two-phase driving method, and is driven by horizontal transfer clocks Hφ1 and Hφ2 having different phases. Is done. The horizontal transfer clocks Hφ1 and Hφ2 are output from the timing generator 6. The horizontal transfer output unit 4 includes an FD amplifier (floating diffusion amplifier) 48 provided at the exit of the horizontal transfer register 45. The signal charge transferred from the first vertical transfer register 25 to the horizontal transfer register 45 and the dark charge (dark current charge) transferred from the second vertical transfer register 35 to the horizontal transfer register 45 are converted into one horizontal scanning line. The data is input to the FD amplifier 48 by minutes.

  The FD amplifier 48 converts the signal charge input from the horizontal transfer register 45 into a voltage signal (referred to as a pixel signal for convenience) according to the amount of charge. Further, the dark charge input from the horizontal transfer register 45 is converted into a voltage signal corresponding to the amount of charge (also referred to as “black signal” for convenience). Then, the pixel signal and the black signal of each vertical column are output to the processing circuit 5 by one horizontal scanning line.

  The processing circuit 5 performs black level compensation processing, FD reset noise subtraction processing, and the like based on the pixel signal and the black signal output from the horizontal transfer output unit 4, and an image of incident light incident on the light receiving region 2a ( Subject image).

  In the solid-state imaging device 1 having such a configuration, a signal charge corresponding to the amount of received light photoelectrically converted by each first photosensor 20 within a time (for example, 1/60 seconds) according to the readout method will be described later. Data is read out to the first vertical transfer register 25 connected through the read gate 24. The read signal charges and dark charges generated in the first vertical transfer register 25 due to the thermal excitation of the semiconductor structure are mixed in the first vertical transfer register 25, and the first vertical transfer register 25 to the horizontal transfer register 45. Forwarded to In addition, dark charges generated in the second vertical transfer register 35 due to thermal excitation of the semiconductor structure are transferred from the second vertical transfer register 35 to the horizontal transfer register 45.

  Then, the black level is set with reference to the black signal obtained by converting the dark charge transferred from the second vertical transfer register 35 into a voltage. In the processing circuit 5, the black signal is subtracted from the pixel signal transferred from the first vertical transfer register 25 and converted from the signal charge to which the dark charge is added into the voltage signal, thereby changing the thermal excitation state. The resulting lightness float of the image is removed.

[2. Configuration of Light Receiving Area 2a and Optical Black Area 2b]
In the solid-state imaging device 1 schematically configured as described above, a cross-sectional view (cross-sectional view of a pixel in the light receiving region 2a) taken along II-II in FIGS. 1 and 2 is shown in FIG. FIG. 4 shows a cross-sectional view taken along the arrow III (a cross-sectional view of a pixel in the optical black region 2b).

  As shown in FIG. 3, each pixel in the light receiving region 2a includes a first photosensor 20, a read gate 24, a first vertical transfer register 25, a channel stop 28, and the like that receive incident light.

The first photosensor 20 basically includes an N-type semiconductor region 21 formed on the P-well region 11 of the N-type silicon substrate 10 and a P-type semiconductor region 22 formed on the N-type semiconductor region 21. It is a component. Then, an HAD sensor (Hole Accumulation Diode Sensor) is configured by these P ⁺ NPN junctions. The N-type semiconductor region 21 is an N-type impurity diffusion region, and the P-type semiconductor region 22 is a P-type impurity diffusion region. The N-type semiconductor region 21 is a region in which the concentration of N-type impurities (for example, arsenic) is, for example, about 1 × 10 ^{17 to} 5 × 10 ¹⁷ pieces / cm ³ . The P-type semiconductor region 22 is a region having a P-type impurity (for example, boron) concentration of about 1 × 10 ^{18 to} 5 × 10 ¹⁸ / cm ³ , for example.

A P + region 26 is formed on the P well region 11 and an N-type impurity diffusion region (hereinafter referred to as a transfer channel region) 27 is formed on the P + region 26 with the read gate 24 interposed therebetween. The read gate 24 is a region where the concentration of a P-type impurity (for example, boron) is about 1 × 10 ^{16 to} 5 × 10 ¹⁶ / cm ³ , for example. The P + region 26 is a region where the concentration of P-type impurities (for example, boron) is about 1 × 10 ^{16 to} 5 × 10 ¹⁶ / cm ³ , for example. The transfer channel region 27 is a region where the concentration of N-type impurities (for example, arsenic) is about 1 × 10 ^{17 to} 5 × 10 ¹⁷ / cm ³ , for example.

In addition, a P-type impurity diffusion region is formed between the transfer channel region 27 and the first photosensor 20 of the adjacent pixel to form a channel stop 28. This channel stop 28 is a region where the concentration of P-type impurities (for example, boron) is, for example, about 1 × 10 ^{17 to} 5 × 10 ¹⁷ atoms / cm ³ .

  A read electrode 29 a made of polycrystalline silicon is formed on the read gate 24, the transfer channel region 27, and the channel stop 28 with a gate insulating film (not shown) interposed therebetween, and the first vertical transfer register 25 is configured.

  A light transmissive interlayer insulating film 17 made of, for example, phosphorus silicate glass (PSG) is laminated on the entire surface covering the first photosensor 20 and the first vertical transfer register 25. A light shielding film (for example, an Al film or a W film) 18 having an opening above the first photosensor 20 and covering the first vertical transfer register 25 is formed on the interlayer insulating film 17. A surface protective layer 19 is formed to cover the entire surface of the substrate.

  On the other hand, each pixel in the optical black region 2b includes a second photosensor 30, a second vertical transfer register 35, a channel stop 38, and the like, as shown in FIG.

Similar to the first photosensor 20 in the light receiving region 2a, the second photosensor 30 in the optical black region 2b includes an N-type semiconductor region 31 formed on the P-well region 11 of the N-type silicon substrate, and the N-type semiconductor. A P-type semiconductor region 32 formed on the region 31 is a basic component. Therefore, the breakdown tolerance of the optical black region 3 can be made equal to the breakdown tolerance of the light receiving region 2a, and the fluctuation of the black level can be suppressed. Note that the N-type semiconductor region 31 is an N-type semiconductor region having an N-type impurity (for example, arsenic) concentration of, for example, about 1 × 10 ^{17 to} 5 × 10 ¹⁷ / cm ³ . The P-type semiconductor region 32 is a P-type semiconductor region in which the concentration of P-type impurities (for example, boron) is about 1 × 10 ^{18 to} 5 × 10 ¹⁸ / cm ³ , for example.

In the formation region of the second vertical transfer register 35, a P + region 36 is formed on the P well region 11, and a transfer channel region 37 is formed on the P + region 36. The P + region 36 is a P-type semiconductor region having a P-type impurity (for example, boron) concentration of about 1 × 10 ^{16 to} 5 × 10 ¹⁶ / cm ³ , for example. Further, the transfer channel region 37 is an N-type semiconductor region having an N-type impurity (for example, arsenic) concentration of, for example, about 1 × 10 ^{17 to} 5 × 10 ¹⁷ pieces / cm ³ .

A channel stop 38 is formed between the transfer channel region 37 and the second photosensor 30 of the adjacent pixel. Further, a P + region 33 is formed between the transfer channel region 37 and the second photosensor 30. The channel stop 38 is a P-type semiconductor region having a P-type impurity (for example, boron) concentration of about 1 × 10 ^{17 to} 5 × 10 ¹⁷ / cm ³ , for example. The P + region 33 is a P-type semiconductor region in which the concentration of P-type impurities (for example, boron) is about 1 × 10 ^{16 to} 5 × 10 ¹⁶ / cm ³ , for example.

  Then, a read electrode 39a made of polycrystalline silicon is formed on the transfer channel region 37 and the channel stop 38 with the insulating film 17a interposed therebetween, and the second vertical transfer register 35 is configured. The interlayer insulating film 17b and the light shielding film 18 are formed on the entire surface (the entire optical black region) covering the second photosensor 30 and the second vertical transfer register 35, and the surface protective layer 19 is formed on the uppermost layer.

  Here, as described above, the photosensor 30 in the optical black region 2b is the N-type semiconductor region 31 formed on the P-well region 11 of the N-type silicon substrate, similarly to the first photosensor 20 in the light-receiving region 2a. have. For this reason, the leaked light that has entered the gap between the light shielding film 18 and the N-type silicon substrate 10 into the second photosensor 30 in the optical black region 2b and enters multiple reflections is photoelectrically converted, and the black level may fluctuate. It was.

  Therefore, in the optical black region 2b according to the present embodiment, the read electrode 39a in the optical black region 2b is separated from the N-type semiconductor region 31 by a predetermined distance d, unlike the read electrode 29a in the light receiving region 2a. Yes. This prevents electrons from being read out to the vertical transfer register 35 in the same manner as the light receiving region 2a at the time of reading. That is, as shown in FIG. 4B, when the readout electrode 39a 'is close to the N-type semiconductor region 31', the potential of the P + region 33 'is lowered and charges are read from the N-type semiconductor region 31'. However, in the optical black region 2b according to the present embodiment, the read electrode 39a is moved away from the N-type semiconductor region 31, so that the potential of the P + region 33 ′ is lowered and charges are not read from the N-type semiconductor region 31 ′. Yes.

  In the example shown in FIG. 4A, the P + region 33 is not disposed immediately below the read electrode 39a to suppress the potential of the P + region 33 from being lowered. However, charges are read from the N-type semiconductor region 31. If not, the P + region 33 may be disposed so as to straddle the read electrode 39a.

  That is, in the optical black region 2b, the distance d between the readout electrode 39a and the second photosensor 30 is a distance at which no charge is read from the second photosensor 30 when a readout voltage is applied to the readout electrode 39a. . By configuring the optical black area 2b in this way, it is possible to suppress the breakdown of the optical black area 2b and the black level fluctuation due to large light quantity shooting, and to prevent the problem of whitening.

  In particular, the width of the read electrode 39a in the optical black region 2b is made narrower than the width of the read electrode 29a in the light receiving region 2a, so that when the read voltage is applied to the read electrode 39a, the second photo sensor The distance from 30 is the distance at which no charge is read out. Therefore, after designing the photosensors 20 and 30 and the vertical transfer registers 25 and 35 with the same configuration, it is only necessary to narrow the width of the readout electrode 39a, and the layout design is extremely easy.

[3. Manufacturing method of solid-state imaging device]
Next, a method for manufacturing the solid-state imaging device 1 will be specifically described with reference to FIGS. 5A to 5H and FIG. Here, a method for manufacturing the optical black region 2b, which is a characteristic part in the present embodiment, will be described, and a method for manufacturing the light receiving region 2a will be omitted.

First, as shown in FIG. 5A, an N-type silicon substrate 10 that is a semiconductor substrate is prepared, and P-type impurities are ion-implanted into the upper portion of the N-type silicon substrate 10 to form a P well region 11 (first conductivity type). Well region). Here, the P-type impurity is, for example, B (boron), and the impurity concentration of the P well region 11 is, for example, about 1 × 10 ^{15 to} 5 × 10 ¹⁵ / cm ³ .

Next, as shown in FIG. 5B, N-type impurities are ion-implanted into the P-well region 11 where the second photosensor 30 is to be formed, thereby forming an N-type semiconductor region 31 (second conductivity type semiconductor region). . Here, the N-type impurity is, for example, arsenic, and the impurity concentration of the N-type semiconductor region 31 is, for example, about 1 × 10 ^{17 to} 5 × 10 ¹⁷ / cm ³ .

Next, as shown in FIG. 5C, a P + region 36 is formed by ion-implanting P-type impurities into the P-well region 11 in the region (vertical transfer register formation region) where the second vertical transfer register 35 is formed. Here, the P-type impurity is, for example, B (boron), and the impurity concentration of the P + region 36 is, for example, about 1 × 10 ^{16 to} 5 × 10 ¹⁶ / cm ³ .

Next, as shown in FIG. 5D, N-type impurities are ion-implanted on the P + region 36 in the region (vertical transfer register formation region) where the second vertical transfer register 35 is formed, thereby forming the transfer channel region 37. Here, the N-type impurity is, for example, arsenic, and the impurity concentration of the transfer channel region 37 is, for example, about 1 × 10 ^{17 to} 5 × 10 ¹⁷ / cm ³ .

Next, as shown in FIG. 5E, P-type impurities are ion-implanted into the P-well region 11 between the transfer channel region 37 and the N-type semiconductor region 31 to form a P + region 33 (first-conductivity-type first semiconductor region). ). Here, the P-type impurity is, for example, B (boron), and the impurity concentration of the P + region 33 is, for example, about 1 × 10 ^{16 to} 5 × 10 ¹⁶ / cm ³ .

Next, as shown in FIG. 5F, a P-type impurity is ion-implanted into the P well region 11 between the transfer channel region 37 and the second photosensor 30 to form a channel stop 38. Here, the P-type impurity is, for example, B (boron), and the impurity concentration of the channel stop 38 is, for example, about 1 × 10 ^{17 to} 5 × 10 ¹⁷ / cm ³ .

  Next, as shown in FIG. 5G, after an insulating film 17a is formed on the N-type silicon substrate 10 and the polycrystalline silicon is selectively formed on the transfer channel region 37 and the channel stop 38, the read electrode 39a is formed. Form. Although not shown, the transfer electrode 39b is also formed at this time.

Next, as shown in FIG. 5H, using the readout electrode 39a as a mask, P-type impurities are ion-implanted into the upper surface of the N-type silicon substrate 10 between the transfer channel regions 37 to form a P-type semiconductor region 32 (first conductivity type first electrode). 2 semiconductor regions). Here, the P-type impurity is, for example, B (boron), and the impurity concentration of the P-type semiconductor region 32 is, for example, about 1 × 10 ^{18 to} 5 × 10 ¹⁸ / cm ³ .

  Finally, as shown in FIG. 4A, after the insulating film 17b is formed on the readout electrode 39a and the insulating film 17a, the light shielding film 18 is formed, and the surface protective layer 19 is formed as the uppermost layer.

  On the other hand, the light receiving region 2a is different from the optical black region 2b except that the light receiving region 2a has an opening (see reference numeral 50 shown in FIG. 3) for guiding incident light to the first photosensor 20 and the read electrode 29a is wide. The structure is the same as that of the optical black region 2b. That is, after the P well region 11 is formed, the N type semiconductor region 31 is simultaneously with the N type semiconductor region 21, the P + region 36 is simultaneously with the P + region 26, the transfer channel region 37 is simultaneously with the transfer channel region 27, and the P + region. 33 is formed simultaneously with the read gate 24. The channel stop 38 is formed simultaneously with the channel stop 28, the read electrode 39 a is formed simultaneously with the read electrode 29 a, and the P-type semiconductor region 32 is formed simultaneously with the P-type semiconductor region 22.

  Thus, in the manufacturing method of the optical black region 2b according to the present embodiment, the optical black region 2b can be formed simultaneously with the light receiving region 2a in the same process as the light receiving region 2a. Moreover, even when the width of the conventional readout electrode 39a is changed, the P-type semiconductor region 32 can be formed by self-alignment using the readout electrode 39a as a mask, as in the light receiving region 2a, and the number of processes is increased. I will not let you.

  Although some of the embodiments of the present invention have been described in detail with reference to the drawings, these are exemplifications, and the present invention is implemented in other forms with various modifications and improvements based on the knowledge of those skilled in the art. Is possible.

DESCRIPTION OF SYMBOLS 1 Solid-state image sensor 2 Pixel part 2a Light-receiving area | region 2b Optical black area | region 4 Horizontal transfer output part 10 N type silicon substrate (semiconductor substrate)
11 P well region (well region of first conductivity type)
20 First photosensor 21 N-type semiconductor region 22 P-type semiconductor region 24 Read gate 25 First vertical transfer register 29a, 39a Read electrode 29b, 39b Transfer electrode 30 Second photosensor 31 N-type semiconductor region (second conductivity type) Semiconductor area)
32 P-type semiconductor region (second semiconductor region of first conductivity type)
33 P + region (first conductivity type first semiconductor region)
35 Second vertical transfer register 38 Channel stop 45 Horizontal transfer register

Claims (4)

A plurality of two-dimensionally arranged photosensors, a readout electrode for reading out charges from the photosensors, a transfer electrode for transferring the readout charges, and a vertical transfer register provided for each vertical column of the photosensors. Having a pixel portion;
A horizontal transfer register for horizontally transferring the charges transferred from the vertical transfer register,
The pixel portion includes a light receiving region that receives incident light and an optical black region in which the incident light is shielded by a light shielding film, and the photosensors have the same configuration in the light receiving region and the optical black region. ,
A solid-state imaging device in which, in the optical black region, a distance between the readout electrode and the photosensor is a distance at which charges are not read from the photosensor when a readout voltage is applied to the readout electrode.   When a read voltage is applied to the read electrode, the distance between the read electrode and the photosensor is reduced by making the width of the read electrode in the optical black region smaller than the width of the read electrode in the light receiving region. The solid-state imaging device according to claim 1, wherein a distance from which charges are not read out from the photosensor is set. A solid-state image sensor;
The solid-state imaging device is
A plurality of two-dimensionally arranged photosensors, a readout electrode for reading out charges from the photosensors, a transfer electrode for transferring the readout charges, and a vertical transfer register provided for each vertical column of the photosensors. Having a pixel portion;
A horizontal transfer register for horizontally transferring the charges transferred from the vertical transfer register,
The pixel portion includes a light receiving region that receives incident light and an optical black region in which the incident light is shielded by a light shielding film, and the photosensors have the same configuration in the light receiving region and the optical black region. ,
In the optical black region, an imaging apparatus in which a distance between the readout electrode and the photosensor is a distance at which charges are not read out from the photosensor when a readout voltage is applied to the readout electrode. Forming a first conductivity type well region in a semiconductor substrate;
Forming a transfer channel in the vertical transfer register forming region of the well region;
Forming a second conductivity type semiconductor region in the photosensor formation region of the well region;
Forming a first conductivity type first semiconductor region in the well region between the transfer channel and the second conductivity type semiconductor region;
Forming a readout electrode for reading out charges from the photosensor formed in the photosensor formation region on the transfer channel via an insulating film;
Forming a first conductive type second semiconductor region having an impurity concentration higher than that of the first semiconductor region on the second conductive type semiconductor region and on the first semiconductor region between the read electrodes; ,
Forming a light-shielding film on the semiconductor substrate including the readout electrode and the transfer electrode via an insulating film,
The photosensor includes the second conductivity type semiconductor region and the second semiconductor region,
A method for manufacturing a solid-state imaging device, wherein a distance between the readout electrode and the photosensor is set such that a charge is not read from the photosensor when a readout voltage is applied to the readout electrode.

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