JP2007059733A - Solid-state imaging device, method for manufacturing the same, and image photographing device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent color mixing between adjacent pixels by forming a first conductive well region between a photosensor and a second conductive well region to be an over-flow barrier; and to obtain a highly sensitive solid-state imaging device. <P>SOLUTION: The solid-state imaging device 1 comprises: a first conductive substrate 11; a second conductive epitaxial layer 12 which is formed on the substrate 11 and opposite to the first conductive type; and a second conductive well region 13 which is formed between the substrate 11 and the epitaxial layer 12 having a concentration being higher than that of the epitaxial layer 12. The photosensor 21, a read-out 31, and a vertical charge transfer 41 are formed on the epitaxial layer 12. The first conductive well region 14 is formed between the photosensor 21 and the second conductive well region 13. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a high-sensitivity solid-state imaging device that prevents color mixing between adjacent pixels, a method for manufacturing the solid-state imaging device, and an image photographing apparatus using the solid-state imaging device.

Conventionally, a technique for improving the sensitivity of an overflow barrier of a photosensor formed on a silicon substrate of a solid-state imaging device by extending the depth from the surface of the silicon substrate to 3 μm or more is known (for example, see Patent Document 1). .) However, in the case of this structure, the space between the N-type region of the photosensor and the P-type region of the overflow barrier is an N ⁻ -type region. The depth of becomes deeper. As a result, there is a problem that the saturation charge amount of the photosensor is reduced.

In addition, since the vertical register barrier area and the overflow barrier P-type area are also N ^- type areas, there is a problem that color mixture between adjacent pixels is weak. As a method for improving the color mixture between adjacent pixels, a method of forming a P-type impurity forming a channel stop portion by a plurality of ion implantations with different implantation energies has been proposed (for example, see Patent Document 2). ). However, this method has a problem that the number of steps increases. In addition, since it is necessary to form the channel stop portion with high energy ion implantation, it is necessary to form a thick ion implantation mask made of resist, and it is difficult to finely process the thick resist film. There was also a problem that miniaturization became difficult.

In order to solve the above problems, the region between the P-type region and the overflow barrier of the P-type region of the photo sensor of the barrier region of the N-type region and the vertical register of the photosensor P ^- also contemplated that the mold region However, in this case, the concentration of the P-type impurity that forms the overflow barrier of the photosensor relatively decreases, and the depth of the overflow barrier of the photosensor from the silicon substrate surface becomes shallow, and the sensitivity is reduced accordingly. This causes a problem. In addition, since the electrons photoelectrically converted at the lower part of the vertical register pass through the N-type substrate, there is a problem that the electrons photoelectrically converted at the lower part of the vertical register do not contribute to the sensitivity.

  As a means for simultaneously solving the above-mentioned problems that the color mixture between adjacent pixels is weak and the depth of the overflow barrier of the photosensor from the silicon substrate surface is reduced, and the sensitivity is reduced accordingly. A method has been proposed in which a P-type region is formed between the P-type region of the vertical register barrier region and the P-type region of the overflow barrier of the photosensor so as to be separated from the barrier region of the vertical register. (For example, refer to Patent Document 3). However, even with this method, it is possible to improve the color mixture between adjacent pixels without causing a decrease in sensitivity due to the shallow depth of the overflow barrier of the photosensor from the silicon substrate surface. Since there is no improvement in the point that the electrons photoelectrically converted in the lower part escape to the N-type silicon substrate, the electrons photoelectrically converted in the lower part of the vertical register are not fully utilized, so that high-sensitivity solid-state imaging It was still difficult to obtain an element.

Japanese Patent No. 2576813 (JP-A-8-46167) JP 2004-165462 A Japanese Patent Application No. 2002-324613

  The problem to be solved is that the sensitivity of the solid-state image sensor is increased and color mixing between adjacent pixels cannot be prevented.

  The solid-state imaging device of the present invention is formed between a first conductivity type substrate, an epitaxial layer of a second conductivity type opposite to the first conductivity type formed on the substrate, and between the substrate and the epitaxial layer. A solid-state imaging device in which a well region having a second conductivity type higher in concentration than the epitaxial layer formed is formed, and a photosensor, a readout unit, and a vertical charge transfer unit are formed in the epitaxial layer, And the second conductivity type well region is formed with a first conductivity type well region.

  The solid-state imaging device manufacturing method of the present invention includes a first conductivity type substrate, a second conductivity type epitaxial layer opposite to the first conductivity type formed on the substrate, and the substrate and the epitaxial layer. A method of manufacturing a solid-state imaging device in which a well region of a second conductivity type having a higher concentration than the epitaxial layer formed therebetween is formed, and a photosensor, a readout unit, and a vertical charge transfer unit are formed in the epitaxial layer. The most important feature is that a step of forming a first conductivity type well region between the photosensor and the second conductivity type well region in the epitaxial layer is provided.

  The image capturing apparatus of the present invention is an image capturing apparatus using a solid-state image sensor as an image sensor, wherein the solid-state image sensor is opposite to a first conductivity type substrate and a first conductivity type formed on the substrate. A second conductivity type epitaxial layer and a second conductivity type well region having a higher concentration than the epitaxial layer formed between the substrate and the epitaxial layer are formed. A solid-state imaging device in which a vertical charge transfer unit is formed, and the most important feature is that a first conductivity type well region is formed between the photosensor and the second conductivity type well region. Features.

  In the solid-state imaging device of the present invention, since the first conductivity type well region is formed between the photosensor and the second conductivity type well region, the sensitivity can be improved, and the photosensor There is an advantage that the saturation charge amount does not decrease. In addition, since the lower region of the vertical charge transfer portion and the lower region between the pixels in the vertical direction are not occupied by the well region of the first conductivity type, the color reproducibility is not weakened by color mixture between adjacent pixels. It becomes an excellent solid-state imaging device. In addition, since the electrons photoelectrically converted in the lower portion of the vertical charge transfer unit are sufficiently utilized, a highly sensitive solid-state imaging device is obtained.

  In the method for manufacturing a solid-state imaging device according to the present invention, a first conductivity type well region is formed between the photosensor and the second conductivity type well region in an epitaxial layer. Can be manufactured. In addition, there is an advantage that the saturation charge amount of the photosensor does not decrease. In addition, since the lower region of the vertical charge transfer portion and the lower region between the pixels in the vertical direction are not occupied by the well region of the first conductivity type, the color reproducibility is not weakened by color mixture between adjacent pixels. Can be manufactured. In addition, since the electrons photoelectrically converted in the lower part of the vertical charge transfer unit are sufficiently utilized, a highly sensitive solid-state imaging device can be manufactured.

  The image capturing apparatus of the present invention uses the solid-state image sensor of the present invention for the image sensor, so that there is no color mixing, so an image with excellent color reproducibility can be obtained, and a highly sensitive image can be obtained. There is an advantage.

  For the purpose of obtaining a solid-state image pickup device that prevents color mixture between adjacent pixels and has high sensitivity, a method for manufacturing the solid-state image pickup device, and an image photographing apparatus using the solid-state image pickup device, a photosensor and an overflow barrier are provided. This is realized by forming a first conductivity type well region spaced apart from the photosensor between the conductivity type well region.

  A first embodiment of the solid-state imaging device according to the present invention will be described with reference to schematic sectional views of FIGS. 1 and 2 and a plan layout view of FIG. 1 is a schematic diagram showing a cross section taken along line X-X ′ in FIG. 3, and FIG. 2 is a schematic diagram showing a cross section taken along line Y-Y ′ in FIG. 3.

As shown in FIGS. 1 to 3, a second conductivity type (P ⁻ type) epitaxial layer 12 opposite to the first conductivity type is formed on a first conductivity type (N type) substrate 11. . Between the substrate 11 and the epitaxial layer 12, a second conductivity type first well region 13 serving as an overflow barrier having a higher concentration than the epitaxial layer 12 is formed. The first well region 13 is formed, for example, with a depth of 3 μm or more, preferably 4 μm or more from the surface of the epitaxial layer 12. Thus, by forming the first well region 13 serving as an overflow barrier at a deep position, the solid-state imaging device 1 with high sensitivity is obtained.

A photo sensor 21 that photoelectrically converts light incident on the solid-state imaging device 1 is formed on the surface side of the epitaxial layer 12. The photosensor 21 is composed of an N-type region 22, and a hole accumulation layer 23 composed of a P ⁺ -type region is formed on the surface layer thereof.

A vertical charge transfer unit 41 is formed on one side (in FIG. 1) of the photosensor 21 via a reading unit 31. The vertical charge transfer portion 41 is composed of an N-type region 42, and a second well region 43 of a P-type region is formed thereunder. Further, a channel stop region 51 made of a P ⁺ type region is formed on the opposite side of the vertical charge transfer unit 41 from the readout unit 31. A channel stop region (not shown) is also formed on the other side (in FIG. 1) of the photosensor 21.

A first conductivity type (N ⁻ -type) well region 14 is formed between the photosensor 21 and the second conductivity type first well region 13 so as to be separated from the photosensor 21. Therefore, the epitaxial layer 12 exists as a second conductivity type region between the photosensor 21 and the first conductivity type well region 14. The first conductivity type well region 14 is formed to extend from the readout unit 31 to the lower side of the vertical charge transfer unit 41. The well region 14 is formed so that the end of the well region 14 on the vertical charge transfer unit 41 side is in a range from the boundary between the readout unit 31 and the vertical charge transfer unit 41 to the center of the vertical charge transfer unit 41. Has been.

The second conductivity type first well region 13 is formed at a higher concentration in the region below the vertical charge transfer portion 41 than in the region below the photosensor 21. The region formed at this high concentration is referred to as a third well region 15. For example, the first well region 13 is formed at a concentration of about 5.0 × 10 ¹⁴ / cm ^{3 to} 2.0 × 10 ¹⁵ / cm ³ , and the third well region 15 is 1.0 × 10 ¹⁵ / cm ³ to about 1.0 × 10 ¹⁵ / cm ³ . The concentration is about 4.0 × 10 ¹⁵ / cm ³ .

  Furthermore, an electrode (transfer electrode and readout electrode) 61 is formed on the epitaxial layer 12 in the readout section 31 and the vertical charge transfer section 41 via an insulating film (not shown). Further, a light shielding film 62 is formed through an insulating film (not shown), and an opening 63 is formed in the light shielding film 62 on the photosensor 21.

In the solid-state imaging device 1 configured as described above, an N ⁻ type well region 14 is formed below the N type region 22 of the photosensor 21 with a certain distance from the N type region 22 of the photosensor 21. The N ⁻ type well region 14 is extended to the central portion below the vertical charge transfer portion 41 on the readout portion 31 side. The impurity concentration of the P-type impurity region serving as the overflow barrier in the region other than the photosensor 21, that is, the third well region 15 is the impurity concentration of the first well region 13 of the P-type impurity region serving as the overflow barrier of the photosensor 21. It is deeper than that. As a result, the potential graph along line AA ′ in FIG. 1 in FIG. 4, the potential graph along lines BB ′ and CC ′ in FIG. 1 in FIG. 5, and D in FIG. 2 in FIG. As shown in the potential graph of the −D ′ line, in the solid-state imaging device 1 configured as described above, a barrier region that prevents color mixing between adjacent pixels is formed between the adjacent photosensors 21, and the vertical charge transfer unit 41. Electrons that have undergone photoelectric conversion at the lower part of the substrate flow into one photosensor 21 corresponding to each vertical charge transfer unit 41 without escaping to the substrate 11 side, and the sensitivity of the solid-state imaging device 1 is improved accordingly. become.

  Further, the solid-state imaging device 1 has improved sensitivity because the first conductivity type well region 14 is formed apart from the photosensor 21 between the photosensor 21 and the second conductivity type well region 13. In addition, the saturation charge amount of the photosensor does not decrease. Further, since the lower region of the vertical charge transfer portion 41 is not occupied by the first conductivity type well region 14, the solid-state imaging device 1 having excellent color reproducibility is not weakened by color mixture between adjacent pixels. It becomes. Further, since the well region 14 of the first conductivity type is extended to the central portion below the vertical charge transfer portion 41, electrons photoelectrically converted at the bottom of the vertical charge transfer portion 41 do not escape to the substrate 11 side. In other words, it flows into one photosensor 21 corresponding to each vertical charge transfer unit 41, and the photoelectrically converted electrons are fully utilized. Therefore, the highly sensitive solid-state imaging device 1 is obtained.

  Furthermore, in the solid-state imaging device 1, the first well region 13 serving as the overflow barrier of the photosensor 21 is formed with a depth of 3 μm or more from the surface of the epitaxial layer 12. The element 1 has high sensitivity.

  Further, since the end portion of the first conductivity type well region 14 is formed away from the lower portion of the readout portion 31, the potential of the end portion of the first conductivity type well region 14 affects the potential of the readout portion 31. Since the influence can be reduced, even when the mask displacement of the mask for ion implantation used when forming the first conductivity type well region 14 occurs, the variation in the read voltage and the blooming margin is suppressed to be smaller than that in the conventional structure. be able to.

  Next, a second embodiment of the solid-state imaging device according to the present invention will be described with reference to schematic sectional views of FIGS. 7 is a schematic view of the cross-sectional view taken along the line XX ′ in the plan layout diagram shown in FIG. 3 as in FIG. 1, and FIG. 8 is shown in FIG. 3 as in FIG. It is drawing which shows the outline of the YY 'line cross section in the planar layout figure.

As shown in FIGS. 7 to 8, a second conductivity type (P ⁻ type) epitaxial layer 12 opposite to the first conductivity type is formed on a first conductivity type (N type) substrate 11. . Between the substrate 11 and the epitaxial layer 12, a second conductivity type first well region 13 serving as an overflow barrier having a higher concentration than the epitaxial layer 12 is formed. The first well region 13 is formed, for example, with a depth of 3 μm or more, preferably 4 μm or more from the surface of the epitaxial layer 12. Thus, by forming the first well region 13 serving as an overflow barrier at a deep position, a highly sensitive solid-state imaging device 2 is obtained.

A photo sensor 21 that photoelectrically converts light incident on the solid-state imaging device 2 is formed on the surface side of the epitaxial layer 12. The photosensor 21 is composed of an N-type region 22, and a hole accumulation layer 23 composed of a P ⁺ -type region is formed on the surface layer thereof.

A vertical charge transfer unit 41 is formed on one side (in FIG. 7) of the photosensor 21 via a reading unit 31. The vertical charge transfer portion 41 is composed of an N-type region, and a second well region 43 of a P-type region is formed therebelow. Further, a channel stop region 51 made of a P ⁺ type region is formed on the opposite side of the vertical charge transfer unit 41 from the readout unit 31. A channel stop region (not shown) is also formed on the other side (in FIG. 7) of the photosensor 21.

A first conductivity type (N ⁻ -type) well region 14 is formed between the photosensor 21 and the second conductivity type first well region 13 so as to be separated from the photosensor 21. Therefore, the epitaxial layer 12 exists as a second conductivity type region between the photosensor 21 and the first conductivity type well region 14. The first conductivity type well region 14 is formed to extend from the readout unit 31 to the lower side of the vertical charge transfer unit 41. The well region 14 is formed so that the end of the well region 14 on the vertical charge transfer unit 41 side is in a range from the boundary between the readout unit 31 and the vertical charge transfer unit 41 to the center of the vertical charge transfer unit 41. Has been.

  On the lower side of the photosensor 21, the first conductivity type (at the same position as the depth from the surface of the epitaxial layer 12 of the first well region 13 of the second conductivity type below the photosensor 21 or a position deeper than that). An N-type impurity region 16 is formed. The second conductivity type first well region 13 serving as the overflow barrier is formed at a constant concentration throughout the substrate 11.

  Furthermore, an electrode (transfer electrode and readout electrode) 61 is formed on the epitaxial layer 12 in the readout section 31 and the vertical charge transfer section 41 via an insulating film (not shown). Further, a light shielding film 62 is formed through an insulating film (not shown), and an opening 63 is formed in the light shielding film 62 on the photosensor 21.

  In the solid-state imaging device 2 having the above-described configuration, the same operations and effects as those of the solid-state imaging device 1 described in the first embodiment can be obtained.

  Also, the first conductivity type (N-type) impurity region 16 of the second embodiment can be formed in the solid-state imaging device 1 of the first embodiment.

<The manufacturing method of Example 1>
Next, a first embodiment of the method for manufacturing a solid-state imaging device according to the present invention will be described with reference to the manufacturing process sectional views of FIGS. In this manufacturing process, a process for manufacturing the solid-state imaging device 1 of the first embodiment will be described. 9 to 15 show cross sections at the same positions as in FIG. 1 in FIG. The manufacturing process described in FIGS. 9 to 15 is a manufacturing process of the solid-state imaging device 1, and the same reference numerals as those of the solid-state imaging device 1 are assigned to the components described below.

  As shown in FIG. 9A, a substrate 11 is prepared. This substrate 11 was made of a first conductivity type (N-type) silicon substrate and had a resistivity of about 1 Ω · cm to 10 Ω · cm.

Next, as shown in FIG. 9B, a P ⁻ type epitaxial layer 12 is formed on the substrate 11 by an epitaxial growth method. The epitaxial layer 12 has a resistivity of about 100 Ω · cm to 500 Ω · cm, for example.

  Next, as shown in FIG. 10 (3), a second conductivity type (P type) first well region 13 is formed between the substrate 11 and the epitaxial layer 12. The first well region 13 is formed, for example, below a region where a photosensor is formed. It may be formed on the entire surface between the substrate 11 and the epitaxial layer 12. The first well region 13 can be formed by ion implantation, for example.

Next, as shown in FIG. 10 (4), a second well type (P type) third well region 15 is formed between the substrate 11 and the epitaxial layer 12. The third well region 15 is formed, for example, below a region other than the region where the photosensor is formed, for example, below a reading unit, a charge transfer unit, a channel stop region, and the like. It may be formed on the entire surface between the substrate 11 and the epitaxial layer 12. The third well region 15 is formed at a higher concentration than the first well region 13. For example, the first well region 13 is formed at a concentration of about 5.0 × 10 ¹⁴ / cm ^{3 to} 2.0 × 10 ¹⁵ / cm ³ , and the third well region 15 is 1.0 × 10 ¹⁵ / cm ³ to about 1.0 × 10 ¹⁵ / cm ³ . It is formed at a concentration of about 4.0 × 10 ¹⁵ / cm ³ . The third well region 15 can be formed by ion implantation, for example.

Next, as shown in FIG. 11 (5), the region in the epitaxial layer 12 where the photosensor is formed and the first well region 13 are separated from the region where the photosensor is formed. A well region 14 of the first conductivity type (N ⁻ type) is formed. The well region 14 can be formed by ion implantation, for example. The well region 14 of the first conductivity type is formed to extend from a readout portion formed later to the lower side of the vertical charge transfer portion. The well region 14 has an end on the vertical charge transfer portion side formed after the well region 14 in a range from the boundary portion between the readout portion and the vertical charge transfer portion formed later to the central portion of the vertical charge transfer portion. It is formed as is.

Next, as shown in FIG. 11 (6), a channel stop region 51 made of a P ⁺ -type region is formed at a predetermined position on the surface layer of the epitaxial layer 12. This channel stop region 51 can be formed by ion implantation.

  Next, as shown in FIG. 12 (7), a second well comprising a P-type region in a region where a vertical charge transfer portion is formed adjacent to the channel stop region 51 at a predetermined position on the surface layer of the epitaxial layer 12. Region 43 is formed. The second well region 43 can be formed by ion implantation.

  Next, as shown in FIG. 12 (8), an N-type region 42 of the vertical charge transfer portion 41 composed of an N-type region is formed adjacent to the channel stop region 51 at a predetermined position on the surface layer of the epitaxial layer 12. . The N-type region 42 of the vertical charge transfer unit 41 can be formed by ion implantation.

  Next, as shown in FIG. 13 (9), an electrode (transfer electrode and a transfer electrode) is formed on the vertical charge transfer portion 41 on the epitaxial layer 12 and on the region to be the readout portion 31 through an insulating film (not shown). Readout electrode) 61 is formed. The electrode 61 may be formed so as to overlap the channel stop region 51. In the electrode formation, for example, after forming an insulating film on the surface of the epitaxial layer 12, a polysilicon film is formed as the electrode forming film. Thereafter, a polysilicon film can be formed on the transfer electrode 61 by an etching technique using a normal resist mask.

  Next, as shown in FIG. 13 (10), an N-type region 22 of the photosensor 21 is formed adjacent to the readout portion 31 of the surface layer of the epitaxial layer 12. The N-type region 22 of the photosensor 21 can be formed by ion implantation.

Next, as shown in FIG. 14 (11), a hole accumulation layer 23 composed of a P ⁺ -type region is formed on the surface layer of the N-type region 22 of the photosensor 21. The hole accumulation layer 23 can be formed by ion implantation.

  Next, as shown in FIG. 15 (12), a light-transmitting interlayer insulating film (not shown) is formed on the entire surface, and then a light shielding film 62 is formed on the entire surface. Thereafter, the light shielding film 62 is etched by an etching technique using a normal resist mask to form an opening 63 on the photosensor 21. In this way, the solid-state image sensor 1 is formed.

In the method for manufacturing the solid-state imaging device, the N ⁻ type well region 14 is formed below the N type region 22 of the photosensor 21 with a certain distance from the N type region 22 of the photosensor 21. The N ⁻ type well region 14 is formed to extend to the vicinity of the central portion below the vertical charge transfer portion 41 on the readout portion 31 side. The impurity concentration of the P-type impurity region serving as the overflow barrier in the region other than the photosensor 21, that is, the third well region 15 is the impurity concentration of the first well region 13 of the P-type impurity region serving as the overflow barrier of the photosensor 21. It is formed deeper than. As a result, in the solid-state imaging device 1 manufactured by the above manufacturing method, a barrier region that prevents color mixture between adjacent pixels is formed between the adjacent photosensors 21, and photoelectric conversion is performed below the vertical charge transfer unit 41. The emitted electrons do not escape to the substrate 11 side and flow into one photosensor 21 corresponding to each vertical charge transfer unit 41, and the sensitivity of the solid-state imaging device 1 is improved accordingly.

  Further, in the above manufacturing method, the first conductivity type well region 14 is formed apart from the photosensor 21 between the photosensor 21 and the second conductivity type well region 13, so that the sensitivity can be improved. In addition, the saturation charge amount of the photosensor does not decrease. Further, since the lower region of the vertical charge transfer portion 41 is not occupied by the first conductivity type well region 14, the solid-state image pickup device 1 having excellent color reproducibility is not weakened by color mixture between adjacent pixels. Can be formed. Further, in the first conductivity type well region 14, electrons photoelectrically converted in the lower part of the vertical charge transfer unit 41 do not escape to the substrate 11 side and flow into one photosensor 21 corresponding to each vertical charge transfer unit 41. Similarly, the end of the well region 14 on the vertical charge transfer portion 41 side is formed so as to be in a range from the boundary portion between the readout portion 31 and the vertical charge transfer portion 41 to the central portion of the vertical charge transfer portion 41. Therefore, the electrons photoelectrically converted at the lower part of the vertical charge transfer unit 41 are fully utilized. Therefore, the highly sensitive solid-state imaging device 1 can be formed.

  Further, in the solid-state imaging device 1, the first well region 13 serving as the overflow barrier of the photosensor 21 is formed so that the depth from the surface of the epitaxial layer 12 is 3 μm or more. The element 1 has high sensitivity.

  Further, since the end portion of the first conductivity type well region 14 is formed away from the lower portion of the readout portion 31, the potential of the end portion of the first conductivity type well region 14 affects the potential of the readout portion 31. Since the influence can be reduced, even if the mask displacement of the mask for ion implantation used when forming the first conductivity type well region 14 occurs, the variation in the read voltage and blooming margin is smaller than that in the conventional structure. Can be suppressed.

In addition, since at least the upper side of the first well region 13 serving as an overflow barrier is formed of the P ⁻ -type epitaxial layer 12, a barrier region for preventing color mixing is formed between adjacent pixels by changing the energy multiple times. Therefore, the number of processes can be reduced without deteriorating the color mixture between adjacent pixels.

<The manufacturing method of Example 2>
Next, a second embodiment of the method for manufacturing a solid-state imaging device according to the present invention will be described with reference to the manufacturing process cross-sectional views of FIGS. In this manufacturing process, a process of manufacturing the solid-state imaging device 2 of Example 2 will be described. 16 to 23 show cross sections at the same positions as in FIG. 1 in FIG. 16 to 23 is a manufacturing process of the solid-state imaging device 2, and the same reference numerals as those of the solid-state imaging device 2 are assigned to the constituent components described below.

  As shown in FIG. 16A, a substrate 11 is prepared. This substrate 11 was made of a first conductivity type (N-type) silicon substrate and had a resistivity of about 1 Ω · cm to 10 Ω · cm.

Next, as shown in FIG. 16B, a P ⁻ type epitaxial layer 12 is formed on the substrate 11 by an epitaxial growth method. The epitaxial layer 12 has a resistivity of about 100 Ω · cm to 500 Ω · cm, for example.

  Next, as shown in FIG. 17C, a first conductivity type (N-type) impurity region 16 is formed in the substrate 11 below the region where the photosensor is formed. The impurity region 16 can be formed by ion implantation, for example. The impurity region 16 is formed at the same position as the depth from the surface of the epitaxial layer 12 in the first well region formed in a later step or at a deeper position.

  Next, as shown in FIG. 17 (4), a second conductivity type (P type) first well region 13 is formed between the substrate 11 and the epitaxial layer 12. The first well region 13 can be formed by ion implantation, for example.

Next, as shown in FIG. 18 (5), the region in which the photosensor is formed in the epitaxial layer 12 and the first well region 13 are separated from the region in which the photosensor is formed. A well region 14 of the first conductivity type (N ⁻ type) is formed. The well region 14 can be formed by ion implantation, for example. The well region 14 of the first conductivity type is formed to extend from a readout portion formed later to the lower side of the vertical charge transfer portion. The well region 14 has an end on the vertical charge transfer portion side formed after the well region 14 in a range from the boundary portion between the readout portion and the vertical charge transfer portion formed later to the central portion of the vertical charge transfer portion. It is formed as is.

Next, as shown in FIG. 18 (6), a channel stop region 51 made of a P ⁺ -type region is formed at a predetermined position on the surface layer of the epitaxial layer 12. This channel stop region 51 can be formed by ion implantation.

  Next, as shown in FIG. 19 (7), a second well comprising a P-type region in a region where a vertical charge transfer portion is formed adjacent to the channel stop region 51 at a predetermined position on the surface layer of the epitaxial layer 12. Region 43 is formed. The second well region 43 can be formed by ion implantation.

  Next, as shown in FIG. 19 (8), an N-type region 42 of the vertical charge transfer portion 41 composed of an N-type region is formed adjacent to the channel stop region 51 at a predetermined position on the surface layer of the epitaxial layer 12. . The N-type region 42 of the vertical charge transfer unit 41 can be formed by ion implantation.

  Next, as shown in FIG. 20 (9), an electrode (transfer electrode and a transfer electrode) is formed on the vertical charge transfer portion 41 and the region to be the readout portion 31 on the epitaxial layer 12 through an insulating film (not shown). Readout electrode) 61 is formed. The electrode 61 may be formed so as to overlap the channel stop region 51. In the electrode formation, for example, after forming an insulating film on the surface of the epitaxial layer 12, a polysilicon film is formed as the electrode forming film. Thereafter, a polysilicon film can be formed on the transfer electrode 61 by an etching technique using a normal resist mask.

  Next, as shown in FIG. 21 (10), an N-type region 22 of the photosensor 21 is formed adjacent to the readout portion 31 of the surface layer of the epitaxial layer 12. The N-type region 22 of the photosensor 21 can be formed by ion implantation.

Next, as shown in FIG. 22 (11), a hole accumulation layer 23 composed of a P ⁺ -type region is formed on the surface layer of the N-type region 22 of the photosensor 21. The hole accumulation layer 23 can be formed by ion implantation.

  Next, as shown in FIG. 23 (12), after forming an interlayer insulating film (not shown) having light transmittance on the entire surface, a light shielding film 62 is formed on the entire surface. Thereafter, the light shielding film 62 is etched by an etching technique using a normal resist mask to form an opening 63 on the photosensor 21. In this way, the solid-state image sensor 2 is formed.

  In the manufacturing method of the solid-state imaging device 2, the same operations and effects as those of the manufacturing method of the solid-state imaging device 1 described in the manufacturing method of the first embodiment can be obtained.

  In the method for manufacturing the solid-state imaging device of the first embodiment, the first conductivity type (N-type) impurity region 16 shown in the method for manufacturing the solid-state imaging device of the second embodiment can also be formed.

  Next, an embodiment of the image photographing apparatus of the present invention will be described with reference to the block diagram of FIG.

  The image capturing apparatus 101 includes a solid-state image sensor 111. An imaging optical system 121 that forms an image is provided on the light condensing side of the solid-state imaging device 111, and a driving circuit 131 that drives the imaging optical system 121 is connected to the solid-state imaging device 111. A signal processing circuit 141 that processes a signal photoelectrically converted by the solid-state imaging device 111 into an image is connected. The image signal processed by the signal processing circuit 141 is stored in the image storage unit 151. In such an image capturing apparatus 101, the solid-state image sensor 111 can be any one of the solid-state image sensor 1 and the solid-state image sensor 2 described in the first and second embodiments.

  Since the image capturing apparatus 101 of the present invention uses the solid-state image sensor 1 or the solid-state image sensor 2 of the present invention for the image sensor, there is no color mixture, so an image with excellent color reproducibility can be obtained and high sensitivity can be obtained. Advantageous image can be obtained.

  The image capturing apparatus 101 of the present invention is not limited to the above configuration, and can be applied to any configuration as long as it is an image capturing apparatus using a solid-state image sensor.

  The solid-state imaging device, the manufacturing method of the solid-state imaging device, and the image photographing apparatus of the present invention can be applied to electronic photographing apparatuses such as an electronic still camera and a camcorder.

FIG. 4 is a schematic cross-sectional view taken along line X-X ′ in FIG. 3 illustrating a first embodiment of the solid-state imaging device of the present invention. FIG. 4 is a schematic cross-sectional view taken along a line Y-Y ′ in FIG. 3 illustrating a first embodiment of the solid-state imaging device of the present invention. 1 is a plan layout diagram illustrating a first embodiment of a solid-state imaging device according to the present invention. It is a potential graph in the A-A 'line in FIG. 2 is a potential graph along B-B ′ line and C-C ′ line in FIG. 1. 3 is a potential graph taken along line D-D ′ in FIG. 2. FIG. 4 is a schematic cross-sectional view taken along line X-X ′ in FIG. 3 showing a second embodiment of the solid-state imaging device of the present invention. FIG. 4 is a schematic cross-sectional view taken along line Y-Y ′ in FIG. 3 illustrating a second embodiment of the solid-state imaging device of the present invention. It is manufacturing process sectional drawing which showed 1st Example which concerns on the manufacturing method of the solid-state image sensor of this invention. It is manufacturing process sectional drawing which showed 1st Example which concerns on the manufacturing method of the solid-state image sensor of this invention. It is manufacturing process sectional drawing which showed 1st Example which concerns on the manufacturing method of the solid-state image sensor of this invention. It is manufacturing process sectional drawing which showed 1st Example which concerns on the manufacturing method of the solid-state image sensor of this invention. It is manufacturing process sectional drawing which showed 1st Example which concerns on the manufacturing method of the solid-state image sensor of this invention. It is manufacturing process sectional drawing which showed 1st Example which concerns on the manufacturing method of the solid-state image sensor of this invention. It is manufacturing process sectional drawing which showed 1st Example which concerns on the manufacturing method of the solid-state image sensor of this invention. It is manufacturing process sectional drawing which showed 2nd Example which concerns on the manufacturing method of the solid-state image sensor of this invention. It is manufacturing process sectional drawing which showed 2nd Example which concerns on the manufacturing method of the solid-state image sensor of this invention. It is manufacturing process sectional drawing which showed 2nd Example which concerns on the manufacturing method of the solid-state image sensor of this invention. It is manufacturing process sectional drawing which showed 2nd Example which concerns on the manufacturing method of the solid-state image sensor of this invention. It is manufacturing process sectional drawing which showed 2nd Example which concerns on the manufacturing method of the solid-state image sensor of this invention. It is manufacturing process sectional drawing which showed 2nd Example which concerns on the manufacturing method of the solid-state image sensor of this invention. It is manufacturing process sectional drawing which showed 2nd Example which concerns on the manufacturing method of the solid-state image sensor of this invention. It is manufacturing process sectional drawing which showed 2nd Example which concerns on the manufacturing method of the solid-state image sensor of this invention. 1 is a block diagram of a schematic configuration showing an embodiment of an image photographing apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 ... Solid-state image sensor, 11 ... Board | substrate, 12 ... Epitaxial layer, 13 ... 1st well area | region, 14 ... 1st conductivity type well area | region, 21 ... Photosensor, 31 ... Read-out part, 41 ... Vertical charge transfer part

Claims (15)

A first conductivity type substrate;
An epitaxial layer of a second conductivity type opposite to the first conductivity type formed on the substrate;
A second conductivity type well region having a higher concentration than the epitaxial layer formed between the substrate and the epitaxial layer is formed;
A solid-state imaging device in which a photosensor, a readout unit, and a vertical charge transfer unit are formed on the epitaxial layer,
A solid-state imaging device, wherein a first conductivity type well region is formed between the photosensor and the second conductivity type well region. The solid-state imaging device according to claim 1, wherein a second conductivity type region exists between the photosensor and the first conductivity type well region. The solid-state imaging device according to claim 2, wherein the second conductivity type region is formed of the epitaxial layer. The solid-state imaging device according to claim 1, wherein the well region of the first conductivity type is formed to extend from the readout unit to a lower side of the vertical charge transfer unit. 5. The solid according to claim 4, wherein an end portion of the well region of the first conductivity type is in a range from a boundary portion between the readout portion and the vertical charge transfer portion to a central portion of the vertical charge transfer portion. Image sensor. 2. The solid-state imaging device according to claim 1, wherein the well region of the second conductivity type is formed at a higher concentration in a region below the vertical charge transfer unit than in a region below the photosensor. On the lower side of the photosensor, a first conductivity type impurity region is formed at the same position as the depth from the surface of the second conductivity type well region under the photosensor or at a position deeper than that. The solid-state imaging device according to claim 1, wherein A first conductivity type substrate;
An epitaxial layer of a second conductivity type opposite to the first conductivity type formed on the substrate;
A second conductivity type well region having a higher concentration than the epitaxial layer formed between the substrate and the epitaxial layer is formed;
A method of manufacturing a solid-state imaging device in which a photosensor, a readout unit, and a vertical charge transfer unit are formed on the epitaxial layer,
A method of manufacturing a solid-state imaging device, comprising: forming a first conductivity type well region between the photosensor and the second conductivity type well region in the epitaxial layer. The method for manufacturing a solid-state imaging device according to claim 8, wherein a second conductivity type region exists between the photosensor and the first conductivity type well region. The method of manufacturing a solid-state imaging device according to claim 9, wherein the second conductivity type region is formed of the epitaxial layer. The method for manufacturing a solid-state imaging device according to claim 8, wherein the well region of the first conductivity type is formed to extend from the readout unit to a lower side of the vertical charge transfer unit. The end portion of the first conductivity type well region is formed in a range from a boundary portion between the readout portion and the vertical charge transfer portion to a central portion of the vertical charge transfer portion. Manufacturing method of solid-state image sensor. 9. The solid-state imaging according to claim 8, wherein the second conductivity type well region below the vertical charge transfer portion is formed at a higher concentration than the second conductivity type well region below the photosensor. Device manufacturing method. A first conductivity type impurity region is formed on the lower side of the photosensor at the same position as the depth from the surface of the second conductivity type well region under the photosensor or at a position deeper than that. The manufacturing method of the solid-state image sensor of Claim 8. In an image capturing apparatus using a solid-state image sensor as an image sensor,
The solid-state imaging device is
A first conductivity type substrate;
An epitaxial layer of a second conductivity type opposite to the first conductivity type formed on the substrate;
A second conductivity type well region having a higher concentration than the epitaxial layer formed between the substrate and the epitaxial layer is formed;
A solid-state imaging device in which a photosensor, a readout unit, and a vertical charge transfer unit are formed on the epitaxial layer,
An image photographing apparatus, wherein a first conductivity type well region is formed between the photosensor and the second conductivity type well region.

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