JP2001144318A - Photoelectric conversion element and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve sensitivity by efficiently taking out a drift current caused by light irradiation as an optical current. SOLUTION: An N-type impurity is injected into a P-type semiconductor substrate 21 at a relatively low dose amount and high energy, embedding an N-diffused layer 35. A P-type flat initial impurity profile is kept in a P-type region 21a of the P-type semiconductor substrate 21 present above the N diffusion layer 35. An N+ region 37 is formed as the contact of the N-diffused layer 35 in a partial region of the P-region 21a. The N-diffused layer 35 and N+ region 37 are formed away from a field oxide film 26 for element isolation, with a P-diffused layer 27 below it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion element and a method of manufacturing the same, and more particularly, to a photoelectric conversion element having high sensitivity to light having a short wavelength such as blue light and a method of manufacturing the same. The photoelectric conversion element is applied to a color CMOS image sensor such as a line sensor or an area sensor, a CCD, or the like.

[0002]

2. Description of the Related Art In a color image sensor composed of a CMOS, a photodiode having little afterimage and capable of high-speed response is often used as a photoelectric conversion element. FIG. 1 shows a circuit diagram of a general photoelectric conversion circuit including a photodiode. The photodiode 1 has a P-channel type MO in which a reset signal 3 is supplied to a gate electrode.
The reset voltage power supply 5 is connected via a switch SW1 composed of an S transistor. When the reset signal 3 is supplied and the switch SW1 is turned on, the photodiode 1 is charged by the reset voltage of the power supply 5 and an initial value is set. When the switch SW1 is turned off and light irradiation starts from that state, a discharge caused by the charge generated in the photodiode 1 is performed for a certain period of time, and is constituted by an N-channel MOS transistor Q1 and an N-channel MOS transistor Q2. The gate potential of the input of the source follower circuit 7 (gate potential of the transistor Q1) is lowered.

The source of the transistor Q1 and the drain of the transistor Q2 are connected to form an output terminal of a source follower circuit 7. A power supply 9 is connected to a drain of the transistor Q1, a source of the transistor Q2 is grounded, and a bias 11 is applied to a gate electrode of the transistor Q2 so that an appropriate load current flows.
The change in the gate potential of the transistor Q1 is proportional to the amount of light applied to the photodiode 1 and the time, and the information is stored in the storage capacitor 13 connected to the output side of the source follower circuit 7.
Is accumulated in The accumulated charge amount is guided to the output buffer 17 by switching of a switch SW2 composed of a P-channel type MOS transistor in which a selection signal 15 from the shift register is applied to the gate electrode, and a signal from each pixel is sequentially output from each output terminal 19. Output serially.

The output voltage in the photoelectric conversion circuit shown in FIG. 1 is proportional to the photocurrent generated in the photodiode 1, and the junction capacitance of the photodiode 1 and the switches SW1, the source follower circuit 7, the switch SW2, etc. It is inversely proportional to the sum of the parasitic capacitances. Therefore, there are two methods for realizing highly sensitive photoelectric conversion, such as increasing the photocurrent of the photodiode 1 or reducing the junction capacitance of the photoelectric conversion circuit including the photodiode 1.

[0005] The simplest method of manufacturing a photodiode in a CMOS process is a method using a PN junction of a source or a drain of a MOS transistor. FIG.
FIG. 11 is a cross-sectional view illustrating a structure of a conventional photodiode. Here, an example is shown in which the light receiving surface is an N ⁺ diffusion layer (a diffusion layer containing an N-type impurity at a relatively high concentration). Photodiode is MO
It is formed in the same step as the source and drain of the S transistor. N ⁺ forming each pixel on the surface of the P-type semiconductor substrate 21
The diffusion layer 23 is formed to form a PN junction. Adjacent N ⁺ diffusion layers 23 are separated by a thick field oxide film 25 formed on the surface of the P-type semiconductor substrate 21 and a P diffusion layer (a diffusion layer containing a P-type impurity) 27 formed immediately below. On the surface of the P-type semiconductor substrate 21, a P ⁺ diffusion layer (a diffusion layer containing a relatively high concentration of P-type impurities) 29 for forming a common potential with the P-type semiconductor substrate 21 is formed.

[0006] N ⁺ interlayer insulating film 31 is formed on the diffusion layer 23 surface and the P ⁺ diffusion layer 29 surface, N ⁺ diffusion layer 23 electrode 23a formed on the interlayer insulating film 31 on the surface, the P ⁺ diffusion layer On the surface of the electrode 29, an electrode 29 formed on the interlayer insulating film 31 is formed.
a are connected to each other through contact holes formed in the interlayer insulating film 31. Field oxide film 25
A final protective film 33 is formed on the upper electrodes 23a and 29a and on the interlayer insulating film 31. A pad opening is formed in the final protective film 33 on the electrodes 23a and 29a.
N ⁺ diffusion layer 23 is connected to cathode electrode 23 through electrode 23a.
b, and the P ⁺ diffusion layer 29 is connected to the anode electrode 29b via the electrode 29a.

In a photodiode as shown in FIG. 2,
The junction capacitance per unit area is determined by the junction area between the P-type semiconductor substrate 21 and the N ⁺ diffusion layer 23, similarly to the source and drain of the MOS transistor. If the junction area is reduced in order to reduce the junction capacitance, the effective light receiving area also decreases at the same time, which does not lead to an improvement in sensitivity. Therefore, in order to improve the sensitivity, it is necessary to reduce the junction capacitance per unit area by some method while securing the light receiving area.

On the other hand, as for the photocurrent, the intensity of the light applied to the semiconductor substrate surface decreases exponentially in the depth direction due to absorption. In particular, light having a short wavelength such as blue has a large absorption coefficient and is remarkably attenuated. Therefore, for short-wavelength light, it is important to form a depletion layer region that generates a photocurrent most efficiently, that is, a PN junction at a shallow position. Since the junction depth of the PN junction of the source and drain of the MOS transistor is determined so that appropriate transistor characteristics can be obtained, the junction of the photodiode must be connected to the source of the MOS transistor in order to obtain a shallower PN junction. , Must be formed in a separate process from the drain.

PN for improving the sensitivity of a photodiode
As a method for forming the junction, for example, there are Japanese Patent No. 2792219 and Japanese Patent Application Laid-Open No. 9-298308. In Japanese Patent No. 2792219, a PN junction is formed at an end of an element isolation oxide film around a light receiving element, so that a junction area ratio is reduced as compared with a light receiving area to reduce a junction capacitance. The light receiving area is assumed to be the entire element region since the diffusion current is mainly caused by carriers generated in the semiconductor substrate. Japanese Patent Application Laid-Open No. 9-298308 discloses that a PN junction is formed by forming an impurity diffusion layer such that the impurity concentration is shallow, has a relatively low impurity concentration, and the impurity concentration increases as approaching the surface. The sensitivity of is improved. Here, due to the action of an electric field caused by the impurity profile of the impurity diffusion layer whose concentration increases as approaching the surface, carriers generated near the surface are converted into P ions inside the surface.
It leads to the depletion layer region of the N junction and contributes as a photocurrent.

[0010]

However, Japanese Patent No. 279
In the structure of the photodiode described in Japanese Patent No. 2219,
The drift current due to the carrier generated in the depletion layer that generates the photocurrent most efficiently is expected to contribute little because the junction area is small, and may cause a decrease in sensitivity.
In the structure of the photodiode described in JP-A-9-298308, the electric field caused by the impurity profile of the impurity diffusion layer is smaller than the electric field in the depletion layer. It is considered that the ratio of carriers that recombine before being taken out as a photocurrent is higher than that of.

Accordingly, the present invention provides a method of efficiently extracting a drift current caused by light irradiation as a photocurrent.
In particular, it is an object of the present invention to provide a photoelectric conversion element with improved sensitivity to short-wavelength light such as blue light and a method for manufacturing the same.

[0012]

According to the photoelectric conversion element of the present invention, a second conductivity type diffusion layer embedded in a semiconductor substrate of a first conductivity type is formed. A PN junction is formed at the end, a substrate surface in a region where the second conductivity type diffusion layer is located is a light receiving surface, and a reverse bias voltage is applied to the PN junction.

Forming a second conductivity type diffusion layer embedded inside a first conductivity type semiconductor substrate to form a depletion layer region of a PN junction around an upper portion of the second conductivity type diffusion layer. And more drift current can be extracted as photocurrent.

The method for manufacturing a photoelectric conversion element according to the present invention comprises:
The second conductivity type impurity is ion-implanted with high energy into the conductivity type semiconductor substrate, and the upper, lower and end portions of the first conductivity type semiconductor substrate embedded in the first conductivity type semiconductor substrate are embedded. A second conductivity type diffusion layer surrounded by the one conductivity type region is formed.

Forming a second conductivity type diffusion layer inside the first conductivity type semiconductor substrate by ion-implanting a second conductivity type impurity into the first conductivity type semiconductor substrate at a high energy and a relatively low dose; Thereby, the second conductivity type diffusion layer can be easily formed by a simple manufacturing process.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In a photoelectric conversion element according to the present invention, an electrode extraction portion (contact) of a second conductivity type diffusion layer.
Preferably, a second conductivity type region having a higher impurity concentration than the second conductivity type diffusion and extending from the surface of the first conductivity type semiconductor substrate is connected to the second conductivity type diffusion layer. As a result, it is possible to efficiently extract a drift current generated by light irradiation as a photocurrent, reduce the series resistance on the cathode electrode side, and prevent a reduction in response speed.

A first conductivity type diffusion layer is formed as a channel dope layer under a thick oxide film layer for element isolation.
It is preferable that the second conductivity type diffusion layer and the second conductivity type region having a high impurity concentration are formed at an interval from the thick oxide film layer and the first conductivity type diffusion layer. As a result, the extension of the depletion layer is not hindered by the thick oxide film layer and the first conductivity type diffusion layer, and an increase in junction capacitance can be avoided. Further, since the bonding position is far from the region where the residual stress is large at the end of the field oxide film, it is possible to suppress the low dark current.

The second conductivity type diffusion layer is preferably formed under a concentration condition that depletes all or most of the inside. The concentration condition is, for example, that the impurity concentration of the semiconductor substrate of the first conductivity type is 1 × 10 ¹⁴ to 1 × 10 ¹⁶ / c.
m ³ , the impurity concentration of the second conductivity type diffusion layer is 1 × 10 ¹⁵ to 1
× 10 ¹⁷ / cm ³ . As a result, the junction capacitance is reduced, and the generated carriers do not recombine and disappear, and all generated carriers become drift current components.

The first conductivity type region present above the second conductivity type diffusion layer is preferably formed under a concentration condition that depletes at least to the vicinity of the surface during operation. The concentration conditions are, for example, that the impurity concentration of the semiconductor substrate of the first conductivity type is 1 × 10 ¹⁴ to 1 × 10 ¹⁶ / cm ³ and the impurity concentration of the diffusion layer of the second conductivity type is 1 × 10 ¹⁵ to 1 × 10 ¹⁷ / cm ³ . cm ³
The thickness of the first conductivity type region is about 0.1 to 0.5 μm. As a result, carriers generated near the surface with respect to light of a short wavelength such as blue having a large absorption coefficient can be collected in the depletion layer.

The conductivity type near the surface of the first conductivity type region existing above the second conductivity type diffusion layer is caused by fixed charges of an oxide film as a surface protection film formed on the surface of the first conductivity type semiconductor substrate. Preferably, it is inverted. For example, the impurity concentration of the semiconductor substrate of the first conductivity type is 1 × 10 ¹⁴ to 1 × 10 ¹⁶
/ Cm ³ , the conductivity type near the surface of the first conductivity type region is naturally inverted. As a result, it is possible to reduce dark current caused by the surface recombination of minority carriers thermally generated on the outermost surface.

In the manufacturing method according to the present invention, apart from the step of forming the second conductivity type diffusion layer, the second conductivity type diffusion layer is formed in a part of the first conductivity type region existing above the second conductivity type diffusion layer. The second conductivity type impurity is ion-implanted to a higher concentration than the layer, and the second conductivity type region having a high impurity concentration is electrically connected from the surface of the first conductivity type semiconductor substrate to the second conductivity type diffusion layer. Preferably, it is formed as a take-out part. As a result, the drift current caused by light irradiation can be efficiently extracted as a photocurrent, the series resistance on one electrode side is reduced, and the second conductivity type diffusion layer that prevents a decrease in response speed can be easily manufactured by a simple manufacturing process. Can be formed.

[0022]

FIG. 3 is a sectional view showing the structure of an embodiment in which a photoelectric conversion element according to the present invention is applied to a photodiode. 2 are given the same reference numerals. Here, an example is shown in which a photodiode having a light-receiving surface having an N diffusion layer (a diffusion layer containing an N-type impurity) is applied to a photodiode array (line sensor) in which one-dimensional array is provided. However, the present invention is not limited to this embodiment, and various changes can be made within the scope of the claims.

The impurity concentration is 1 × 10 ¹⁴ to 1 × 10 ¹⁶ / c
An N diffusion layer 35 constituting each pixel is buried and formed near the surface of the P-type semiconductor substrate 21 of m ^3.
PN junctions are formed at the upper, lower and end portions of the. N
The diffusion layer 35 is formed, for example, by ion implantation of high-energy phosphorus as an N-type impurity, has a peak inside the P-type semiconductor substrate 21, and has a peak of, for example, 1 × 10 ¹⁵ to 1 × 1.
It is formed at a concentration of 0 ¹⁷ / cm ³ . In the P region 21a of the P-type semiconductor substrate 21 existing above the N-diffusion layer 35, a P-type flat initial impurity profile is maintained. The thickness of the P region 21a is, for example, about 0.1 to 0.5 μm.

An N diffusion layer 3 is formed in a part of the P region 21a.
5, an N ⁺ region 37 as a contact in which, for example, phosphorus is introduced at a higher concentration than the contact region 5 is formed from the surface of the P-type semiconductor substrate 21 to the N diffusion layer 35. N ⁺ region 37
Phosphorus concentration is ^{5 × 10 1 9 ~5 × 10} 20 / cm 3 , for example. The adjacent N diffusion layer 35 is formed of the field oxide film 25.
And a P diffusion layer 27 thereunder.
Field oxide film 25, P diffusion layer 27 and N diffusion layer 35
And N ⁺ regions 37 are formed at intervals, and PN
The occurrence of dark current is suppressed by separating the junction from the region where the residual stress is large at the end of the field oxide film 25. P as a contact is formed on the surface of the P-type semiconductor substrate 21.
⁺ Diffusion layer 29 is formed.

An interlayer insulating film 31 made of, for example, a silicon oxide film is formed on the surface of the P region 21a and the surface of the P ⁺ diffusion layer 29. The conductivity type near the surface of the P region 21 a is inverted by the fixed charge of the interlayer insulating film 31. This allows
It is possible to reduce dark current caused by the surface recombination of minority carriers thermally generated on the outermost surface. N
An electrode 35a formed on the interlayer insulating film 31 is formed on the surface of the ⁺ region 37, and a contact hole formed on the interlayer insulating film 31 is formed on the surface of the P ⁺ diffusion layer 29 by the electrode 29a formed on the interlayer insulating film 31. Connected to each other.

On the field oxide film 25, the electrodes 29a, 3
For example, a silicon nitride film is formed on 5a and on the interlayer insulating film 31.
Is formed. Electrode 29
Pad openings are formed in the final protective film 33 on the a and 35a.
N diffusion layer 35 is N ⁺Region 37 and electrode 35
a to the cathode electrode 35b via⁺Diffusion layer
29 is connected to an anode electrode 29b via an electrode 29a.
It is. Although not shown, the photodiode array
In the periphery of the device, wiring and the like are formed in the same way as a normal LSI
You.

During the operation of this embodiment, when a reverse bias is applied to the PN junction between the P-type semiconductor substrate 21 including the P region 21a and the N diffusion layer 35, the N-type diffusion layer 35 is formed on the upper, lower and end portions of the N diffusion layer 35. As the depletion layer expands, all or most of the inside of the N diffusion layer 35 is depleted. Thus, carriers caused by light irradiation can be efficiently extracted as a drift current. Further, since a PN junction is formed at the upper, lower, and end portions of the N diffusion layer 35, the junction area increases, but since all or most of the inside of the N diffusion layer 35 is depleted, the junction capacitance is reduced.

Further, since the field oxide film 25 and the P diffusion layer 27 are formed with an interval from the N diffusion layer 35 and the N ⁺ region 37, the extension of the depletion layer is not hindered. Further, in the P region 21a located above the N diffusion layer 35, the P region 21a is depleted to near the surface. This allows carriers generated near the surface due to light irradiation to be collected in the depletion layer. Drift current caused by carriers generated by light irradiation is caused by the N ⁺ region 37 and the electrode 35.
The light is taken out to the cathode electrode 35b as a photocurrent through a. Since the N ⁺ region 37 lowers the series resistance on the cathode electrode 35b side, it is possible to prevent a reduction in response speed.

According to this embodiment, the carrier generated in the depletion layer from the substrate surface to the inside can be taken out as a drift current, so that the sensitivity is improved even for light of short wavelength such as blue having a large absorption coefficient. Therefore, not only the photodiode in which the PN junction as shown in FIG. 2 is formed in the same process as the source and drain junctions of the transistor, but also a large improvement in sensitivity as compared with the conventional photodiode can be expected.

Next, a method of manufacturing the photodiode shown in FIG. 3 will be described as an embodiment of the method of manufacturing the photoelectric conversion element according to the present invention. However, the present invention is not limited to this embodiment, and various changes can be made within the scope of the present invention described in the appended claims.

The photodiode structure of the present invention is manufactured by a manufacturing method characterized by the following. After a P diffusion region 27 and a field oxide film 25 are formed on the surface of the P-type semiconductor substrate 21, a dose of, for example, 5 × 10 ^{10 to} 5 × 10 ¹² / c
m ^2, energy is 500k (kilo) ~1M (Mega) e
Phosphorus is implanted under the condition of V to form the N diffusion layer 35. Thereby, the P-type semiconductor substrate 21 can be formed by a simple manufacturing process.
The N diffusion layer 35 can be formed inside.

The above-described ion implantation is performed at a relatively low dose so as to completely or almost completely deplete the inside of the N diffusion layer 35 by applying a reverse bias applied during operation, and to the P region 2.
Any dose and energy may be used as long as the condition of high energy is such that the impurity profile of 1a remains. The N diffusion layer 35 is preferably formed after the transistor forming step is completed in order to avoid a change in profile due to redistribution.

P region 21 existing above N diffusion layer 35
For example, a dose amount of 1 × 10 ¹⁵ to 1 ×
Phosphorus is implanted under the conditions of 10 ¹⁶ / cm ² and energy of 30 to 50 keV to form an N ⁺ region 37. Thus, the potential of the N diffusion layer 35 is set to P by a simple manufacturing process.
An electrode to be taken out can be formed on the surface of the mold semiconductor substrate 21. Further, in order to reduce the series resistance on the cathode electrode 35b side, it is important to optimize the layout of the N ⁺ region 37. Thereafter, the P ⁺ diffusion layer 29, the interlayer insulating film 31, the electrodes 29a and 35a, the final protective film 33, and the electrodes 29b and 3
5b is formed.

In the embodiment shown in FIG. 3, the present invention is applied to a photodiode having a light-receiving surface having an N diffusion layer, but it is needless to say that the invention can be applied to a photodiode having a P diffusion layer.

[0035]

According to the first aspect of the present invention, the second conductivity type diffusion layer embedded in the first conductivity type semiconductor substrate is formed, and the upper, lower and end portions of the second conductivity type diffusion layer are formed. Is formed, the depletion layer region of the PN junction can be formed around the upper portion of the second conductivity type diffusion layer including the upper portion thereof, and the drift current caused by light irradiation is used as the photocurrent. It can be taken out efficiently.

In the photoelectric conversion device of the second aspect, the second
The electrode extraction portion of the conductive type diffusion layer is formed as a second conductive type region having a higher impurity concentration than that of the second conductive type diffusion and extending from the surface of the first conductive type semiconductor substrate. , The drift current can be efficiently extracted as a photocurrent, the series resistance on the cathode electrode side can be reduced, and a reduction in response speed can be prevented.

According to the third aspect of the present invention, the first conductivity type diffusion layer is formed under the thick oxide film layer for device isolation, and the second conductivity type diffusion layer and the second impurity layer having a high impurity concentration are formed.
Since the conductivity type region is formed with an interval between the thick oxide film layer and the first conductivity type diffusion layer, the extension of the depletion layer is not hindered, and an increase in junction capacitance can be avoided. Since it is far from the region where the residual stress is large at the end of the field oxide film, a low dark current can be suppressed.

In the photoelectric conversion device according to the fourth aspect, the second
Since the conductivity type diffusion layer is formed under a concentration condition in which all or most of the inside thereof is depleted, the junction capacitance is reduced, and the generated carriers do not recombine and disappear. Carriers can be extracted as drift current.

In the photoelectric conversion device of the fifth aspect, the second
Since the first conductivity type region existing above the conductivity type diffusion layer is formed under the concentration condition that depletes at least to the vicinity of the surface during operation, the first conductivity type region is near the surface for short wavelength light such as blue having a large absorption coefficient. Can be collected in the depletion layer.

In the photoelectric conversion device according to claim 6, the second
The conductivity type near the surface of the first conductivity type region existing above the conductivity type diffusion layer seems to be inverted by fixed charges of an oxide film as a surface protection film formed on the surface of the semiconductor substrate of the first conductivity type. Therefore, the dark current generated by the surface recombination of minority carriers thermally generated on the outermost surface can be reduced.

According to a seventh aspect of the present invention, in the method of manufacturing a photoelectric conversion element, the second substrate with high energy can be formed in the semiconductor substrate of the first conductivity type.
A second conductivity type ion-implanted with a conductivity type impurity and buried inside the first conductivity type semiconductor substrate, the upper, lower, and end portions being surrounded by the first conductivity type region of the first conductivity type semiconductor substrate. Since the diffusion layer is formed, the second conductivity type diffusion layer can be easily formed by a simple manufacturing process.

In the method for manufacturing a photoelectric conversion element according to claim 8, the second conductive type diffusion layer is formed separately from the second conductive type diffusion layer.
A second conductivity type impurity is ion-implanted into a part of the first conductivity type region present above the conductivity type diffusion layer at a higher concentration than the second conductivity type diffusion layer, and the second conductivity type impurity is ion-implanted from the surface of the first conductivity type semiconductor substrate. High impurity concentration second layer for electrically connecting up to the two-conductivity type diffusion layer
Since the conductivity type region is formed, the drift current generated by light irradiation can be efficiently extracted as a photocurrent, and the series resistance on the cathode electrode side is reduced,
The second conductivity type diffusion layer for preventing a decrease in response speed can be easily formed by a simple manufacturing process.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a general photoelectric conversion circuit including a photodiode.

FIG. 2 is a cross-sectional view illustrating a structure of a conventional photodiode.

FIG. 3 is a cross-sectional view showing a structure of one embodiment in which a photoelectric conversion element according to the present invention is applied to a photodiode.

[Explanation of symbols]

Reference Signs List 21 P-type semiconductor substrate 21 a, 27 P region 23 N ⁺ diffusion layer 23 a, 29 a, 35 a Electrode 23 b, 35 b Cathode electrode 25 Field oxide film 29 P ⁺ diffusion layer 29 b Anode electrode 31 Interlayer insulation film 33 Final protection film 35 N diffusion layer 35 N ⁺ area

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4M118 AA01 AA05 AB01 BA14 CA04 CA17 CA32 FA06 FA08 FA26 5F049 MA02 MB12 NA01 NA05 NA15 NA18 NB03 NB05 PA09 PA10 QA15 RA03 RA08 SZ12 WA03

Claims (8)

[Claims] 1. A second conductivity type diffusion layer embedded in a first conductivity type semiconductor substrate is formed, and PN junctions are formed at upper, lower and end portions of the second conductivity type diffusion layer.
A photoelectric conversion element, wherein a substrate surface in a region where the second conductivity type diffusion layer is located is a light receiving surface, and a reverse bias voltage is applied to the PN junction. 2. An electrode extraction portion of the second conductivity type diffusion layer, the second conductivity type diffusion layer having a higher impurity concentration than the second conductivity type diffusion layer and extending from a surface of the first conductivity type semiconductor substrate. The photoelectric conversion element according to claim 1, wherein the photoelectric conversion element is formed as a region and connected to the second conductivity type diffusion layer. 3. The method according to claim 1, further comprising the step of forming a first layer under a thick oxide film layer for device isolation.
A conductive type diffusion layer is formed, and the second conductive type diffusion layer and the high impurity concentration second conductive type region are formed with an interval from the thick oxide film layer and the first conductive type diffusion layer. The photoelectric conversion element according to claim 2. 4. The photoelectric conversion element according to claim 1, wherein said second conductivity type diffusion layer is formed under a concentration condition in which all or most of the inside thereof is depleted. 5. The first conductivity type region present above the second conductivity type diffusion layer is formed under a concentration condition that depletes at least to the vicinity of the surface during operation.
The photoelectric conversion element according to any one of the above. 6. A oxidization as a surface protection film formed on the surface of the semiconductor substrate of the first conductivity type, wherein the conductivity type near the surface of the first conductivity type region present above the second conductivity type diffusion layer is formed. The photoelectric conversion element according to any one of claims 1 to 5, wherein the photoelectric conversion element is inverted by a fixed charge of the film. 7. An ion implantation of an impurity of a second conductivity type with high energy into a semiconductor substrate of the first conductivity type to remove the upper, lower and end portions embedded in the semiconductor substrate of the first conductivity type. A method of manufacturing a photoelectric conversion element, comprising forming a second conductivity type diffusion layer surrounded by a first conductivity type region of a first conductivity type semiconductor substrate. 8. In addition to the step of forming the second conductivity type diffusion layer, a part of the first conductivity type region existing on the second conductivity type diffusion layer is formed by the second conductivity type diffusion layer. Also, a second conductivity type impurity is ion-implanted at a high concentration to form a high impurity concentration second conductivity type region electrically connecting the surface of the first conductivity type semiconductor substrate to the second conductivity type diffusion layer. The method for manufacturing a photoelectric conversion element according to claim 7, further comprising the step of: