JP2010040942A - Solid-state imaging apparatus, and method of manufacturing the same - Google Patents

Abstract

High sensitivity is achieved without increasing the chip area and smear.
A solid-state imaging device according to the present invention includes a semiconductor substrate, a photodiode formed on the semiconductor substrate and converting light into a signal charge, and formed on the semiconductor substrate and converted by the photodiode. A vertical transfer channel 3 for transferring the signal charges, an insulating film 4 formed on the surface of the semiconductor substrate 1, a charge transfer electrode 15 formed above the vertical transfer channel 3 via the insulating film 4, and a charge transfer An interlayer insulating film 16a formed on the electrode 15 and an interlayer insulating film 16a formed above the charge transfer electrode 15 via at least one end in a direction perpendicular to the transfer direction of the vertical transfer channel 3, A light shielding film 17 formed on a region where the charge transfer electrode 15 is formed, a contact 18 connecting the charge transfer electrode 15 and the light shielding film 17, and incident light to the photodiode 2. And a micro lens 8b for light.
[Selection] Figure 2

Description

  The present invention relates to a solid-state imaging device and a method for manufacturing the same, and more particularly to a solid-state imaging device including a charge transfer electrode and a light shielding film formed above the charge transfer electrode.

  In recent years, in a solid-state imaging device, the size of cells has been further reduced due to demands for higher resolution and more pixels. On the other hand, the sensitivity level of the solid-state imaging device is required to be the same level as before.

Hereinafter, a conventional solid-state imaging device will be described.
FIG. 7 is a diagram illustrating a configuration of a conventional solid-state imaging device.

  The solid-state imaging device shown in FIG. 7 is a CCD (Charge Coupled Device) image sensor, and includes a plurality of photodiodes 2 arranged in a matrix, a plurality of vertical transfer channels 3 provided for each column, and a horizontal transfer channel. 10.

  The plurality of photodiodes 2 photoelectrically convert incident light into signal charges. The vertical transfer channel 3 transfers the signal charges photoelectrically converted by the plurality of photodiodes 2 arranged in the corresponding column in the vertical direction (column direction).

  The horizontal transfer channel 10 transfers the signal charges transferred by the plurality of vertical transfer channels 3 in the horizontal direction (row direction).

  FIG. 8 is an enlarged view of the region 20 shown in FIG. FIG. 9 is a cross-sectional view taken along the X2-X3 plane of FIG.

  As shown in FIGS. 8 and 9, the conventional solid-state imaging device includes a semiconductor substrate 1, a photodiode 2, a vertical transfer channel 3, a gate insulating film 4, a charge transfer electrode 5, an interlayer insulating film 6a, and 6b, an antireflection film 6c, a light shielding film 7, a color filter layer 8a, and a microlens 8b.

  The light that has passed through the microlens 8 b passes through the opening 7 a of the light shielding film 7 and enters the photodiode 2. The photodiode 2 converts incident light into signal charges.

  Here, if the width (hereinafter referred to as opening width) L6 of the opening 7a of the light shielding film 7 is narrow, the oblique incident lights 9a and 9b are reflected by the light shielding film 7 and do not enter the photodiode 2. That is, in order to improve the sensitivity characteristic of the solid-state imaging device, it is necessary to increase the opening width L6.

  In contrast, Patent Document 1 discloses a technique for increasing the amount of incident light by increasing the opening width.

  In the solid-state imaging device described in Patent Document 1, the light shielding film 7 is formed only on the charge transfer electrode 5. Thereby, the opening width is L6 + 2 × L7. That is, the opening width can be increased by 2 × L7.

  However, in the solid-state imaging device described in Patent Literature 1, the light incident on the vertical transfer channel 3 increases as the distance between the light shielding film 7 and the semiconductor substrate 1 increases from t6 to t7. For example, in the structure in which the light shielding film 7 is also formed on the side surface of the charge transfer electrode 5, the oblique incident light 9 c shown in FIG. 9 is reflected by the light shielding film 7 formed on the side surface of the charge transfer electrode 5. Incident light 9 c does not enter the vertical transfer channel 3. On the other hand, in the solid-state imaging device described in Patent Document 1, the oblique incident light 9c passes directly under the light shielding film 7 and directly enters the vertical transfer channel 3. As a result, smear occurs.

  On the other hand, Patent Document 1 proposes to adopt a frame interline transfer structure (hereinafter referred to as FIT structure) for an increase in smear components.

  FIG. 10 is a diagram illustrating a configuration of a solid-state imaging device having a FIT structure. As shown in FIG. 10, the solid-state imaging device having the FIT structure further includes a charge accumulation region 11 for accumulating signal charges for one screen. In this solid-state imaging device having the FIT structure, the signal charge photoelectrically converted by the photodiode 2 is transferred to the charge storage region 11 at high speed, so that light leakage to the vertical transfer channel 3 can be reduced during vertical transfer. Thereby, generation | occurrence | production of a smear can be reduced.

By using this FIT structure, the solid-state imaging device described in Patent Document 1 can suppress the increase in the smear component described above.
JP 2004-31778 A

  However, when the FIT structure is used, another problem arises that the charge storage region 11 needs to be provided and the chip area increases.

  That is, the conventional solid-state imaging device has a problem that high sensitivity cannot be realized without increasing the chip area and smear.

  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 high sensitivity without increasing the chip area and smear, and a method for manufacturing the same.

  In order to achieve the above object, a solid-state imaging device according to the present invention includes a semiconductor substrate, a light receiving portion that is formed on the semiconductor substrate and converts light into signal charges, and is formed on the semiconductor substrate. A charge transfer channel for transferring the converted signal charge; an insulating film formed on a surface of the semiconductor substrate; a charge transfer electrode formed above the charge transfer channel via the insulating film; and the charge An interlayer insulating film formed on the transfer electrode, and formed above the charge transfer electrode via the interlayer insulating film, and at least one end in the direction perpendicular to the transfer direction of the charge transfer channel is the charge A light-shielding film formed on a region where the transfer electrode is formed, a contact connecting the charge transfer electrode and the light-shielding film, and formed above the light receiving part, and collecting incident light on the light receiving part. And a lens.

  According to this configuration, in the solid-state imaging device according to the present invention, at least one end of the light shielding film is formed on the charge transfer electrode. That is, at least one end of the light shielding film does not cover the side surface of the charge transfer electrode. Thereby, since the opening width of the light shielding film is widened, the amount of light incident on the light receiving portion is increased. Therefore, the solid-state imaging device according to the present invention can realize high sensitivity without increasing the chip area.

  The solid-state imaging device according to the present invention further includes a contact for connecting the charge transfer electrode and the light shielding film. Thereby, since the resistance value of the path (wiring) for applying the charge transfer pulse to the charge transfer electrode is reduced, the solid-state imaging device according to the present invention can improve the vertical transfer speed. Therefore, the solid-state imaging device according to the present invention can suppress an increase in smear caused by the light shielding film not covering the charge transfer electrode without using the FIT structure or the like.

  As described above, the solid-state imaging device according to the present invention can achieve high sensitivity without increasing the chip area and smear.

  In addition, the total thickness of the insulating film under the charge transfer electrode, the charge transfer electrode, and the interlayer insulating film on the charge transfer electrode under the one end of the light shielding film is 150 nm or less. There may be.

  According to this configuration, since the distance between the bottom surface of the light shielding film and the surface of the semiconductor substrate is shortened, light leakage to the charge transfer channel can be reduced. Thereby, the solid-state imaging device according to the present invention can further reduce smear.

  In addition, the light shielding film may be formed at both ends on a region where the charge transfer electrode is formed in a direction perpendicular to the transfer direction of the charge transfer channel.

  According to this structure, since the both ends of the light shielding film do not cover the charge transfer electrode, the opening width of the light shielding film can be further increased. Therefore, the solid-state imaging device according to the present invention can further increase the amount of light incident on the light receiving unit, thereby realizing high sensitivity.

  The light-shielding film has one end formed on a region where the charge transfer electrode is formed in the direction perpendicular to the transfer direction of the charge transfer channel, and the other end formed on the charge transfer electrode. It may be formed outside the region where is formed.

  According to this configuration, the other end of the light shielding film is formed to cover the side surface of the charge transfer electrode. Therefore, the solid-state imaging device according to the present invention can reduce light leakage to the charge transfer channel, thereby reducing smear.

  The interlayer insulating film sandwiched between the light-shielding film and the charge transfer electrode includes a first region having a first film thickness, and a portion under the one end of the light-shielding film, and the first film And a second region having a second film thickness smaller than the thickness.

  According to this configuration, the film thickness of the interlayer insulating film below the end portion (second region) of the light shielding film is smaller than the film thickness of the central portion or the like (first region) of the interlayer insulating film. Thus, by reducing the film thickness of the interlayer insulating film below the end of the light shielding film (second region), light leakage to the charge transfer channel is reduced. Thereby, the solid-state imaging device according to the present invention can reduce smear.

  Furthermore, by increasing the thickness of the central portion of the interlayer insulating film, it is possible to reduce the parasitic capacitance between the light shielding film and the charge transfer electrode that is not backed (not connected via a contact) with the light shielding film. Thereby, the solid-state imaging device according to the present invention can reduce the influence of the charge transfer pulse applied to the light shielding film on the charge transfer electrode not backed by the light shielding film.

The light shielding film may be a metal film.
According to this configuration, since the resistance value of the light shielding film can be reduced, the resistance value of the path (wiring) for applying the charge transfer pulse to the charge transfer electrode can be reduced. Therefore, the solid-state imaging device according to the present invention can improve the vertical transfer speed, thereby suppressing an increase in smear.

  The method for manufacturing a solid-state imaging device according to the present invention includes a step of forming a light receiving portion for converting light into a signal charge on a semiconductor substrate, and transferring the signal charge converted by the light receiving portion to the semiconductor substrate. Forming a charge transfer channel; forming an insulating film on the surface of the semiconductor substrate; forming a charge transfer electrode above the charge transfer channel via the insulating film; and on the charge transfer electrode. Forming the interlayer insulating film, and forming the charge transfer electrode at least at one end in a direction perpendicular to the transfer direction of the charge transfer channel via the interlayer insulating film above the charge transfer electrode. Forming a light-shielding film formed on the region to be formed, forming a contact for connecting the charge transfer electrode and the light-shielding film, and incident light on the light-receiving part above the light-receiving part. And forming a lens optical.

  According to this, in the solid-state imaging device manufactured by the manufacturing method according to the present invention, at least one end of the light shielding film is formed on the charge transfer electrode. That is, at least one end of the light shielding film does not cover the side surface of the charge transfer electrode. Thereby, since the opening width of the light shielding film is widened, the amount of light incident on the light receiving portion is increased. Therefore, the manufacturing method according to the present invention can manufacture a solid-state imaging device capable of realizing high sensitivity without increasing the chip area.

  Furthermore, the solid-state imaging device manufactured by the manufacturing method according to the present invention includes a contact for connecting the charge transfer electrode and the light shielding film. Thereby, since the resistance value of the path (wiring) for applying the charge transfer pulse to the charge transfer electrode is reduced, the solid-state imaging device manufactured by the manufacturing method according to the present invention can improve the vertical transfer speed. Therefore, the solid-state imaging device manufactured by the manufacturing method according to the present invention can suppress an increase in smear caused by the light shielding film not covering the charge transfer electrode without using the FIT structure or the like.

  As described above, the method for manufacturing a solid-state imaging device according to the present invention can manufacture a solid-state imaging device capable of realizing high sensitivity without increasing the chip area and smear.

  Further, the step of forming the interlayer insulating film includes a step of flatly forming a first interlayer insulating film that is a part of the interlayer insulating film, and on the charge transfer electrode and of the charge transfer electrode. Removing the first interlayer insulating film in the second region other than the first region on the charge transfer electrode, leaving the first interlayer insulating film in the first region not including under the one end; Forming a second interlayer insulating film that is a part of the interlayer insulating film on the first interlayer insulating film in the first region and on the charge transfer electrode in the second region.

  According to this, the film thickness of the interlayer insulating film below the end of the light shielding film (second region) is smaller than the film thickness of the central part or the like (first region) of the interlayer insulating film. Thus, by reducing the film thickness of the interlayer insulating film below the end of the light shielding film (second region), light leakage to the charge transfer channel is reduced. Thereby, the solid-state imaging device manufactured by the manufacturing method according to the present invention can reduce smear.

  Furthermore, by increasing the thickness of the central portion of the interlayer insulating film, it is possible to reduce the parasitic capacitance between the light shielding film and the charge transfer electrode that is not backed (not connected via a contact) with the light shielding film. Thereby, the solid-state imaging device manufactured by the manufacturing method according to the present invention can reduce the influence of the charge transfer pulse applied to the light shielding film on the charge transfer electrode not backed by the light shielding film.

  As described above, the present invention can provide a solid-state imaging device capable of realizing high sensitivity without increasing the chip area and smear, and a method for manufacturing the same.

  A solid-state imaging device according to an embodiment of the present invention will be specifically described below with reference to the drawings.

(Embodiment 1)
In the solid-state imaging device according to Embodiment 1 of the present invention, the light shielding film 17 is formed only on the charge transfer electrode 15. Thereby, since the opening width of the light shielding film 17 can be increased, the amount of light incident on the photodiode 2 can be increased without increasing the chip area.

  Furthermore, in the solid-state imaging device according to the first embodiment of the present invention, the light shielding film 17 and the charge transfer electrode 15 are backed, thereby reducing the resistance value of the path of the charge transfer pulse applied to the charge transfer electrode 15. Therefore, the vertical transfer speed can be improved. Thereby, the solid-state imaging device according to Embodiment 1 of the present invention can suppress an increase in smear.

  Furthermore, the solid-state imaging device according to Embodiment 1 of the present invention can reduce light leakage to the vertical transfer channel 3 by shortening the distance between the bottom surface of the light shielding film 17 and the surface of the semiconductor substrate 1. Thereby, the solid-state imaging device according to Embodiment 1 of the present invention can suppress an increase in smear.

  Note that the schematic configuration of the solid-state imaging device according to Embodiment 1 of the present invention is the same as that of FIG.

  FIG. 1 is a plan view of the solid-state imaging device according to Embodiment 1 of the present invention, and is an enlarged view of a region 20 in FIG. 2 is a cross-sectional view taken along the plane X0-X1 in FIG. In addition, the same code | symbol is attached | subjected to the element similar to FIG.8 and FIG.9.

  As shown in FIGS. 1 and 2, the solid-state imaging device according to the first embodiment of the present invention includes a semiconductor substrate 1, a photodiode 2, a vertical transfer channel 3, a gate insulating film 4, and a charge transfer electrode 15. And interlayer insulating films 16a and 6b, an antireflection film 6c, a light shielding film 17, a color filter layer 8a, a microlens 8b, and a contact 18.

The semiconductor substrate 1 is, for example, a silicon substrate.
The photodiode 2 is a light receiving portion formed in the semiconductor substrate 1 and photoelectrically converts light into signal charges.

  The vertical transfer channel 3 is a vertical charge transfer channel for transferring the signal charge photoelectrically converted by the photodiode 2 in the vertical direction.

The insulating film 4 is formed on the surface of the semiconductor substrate 1 and is, for example, a silicon oxide film.
The charge transfer electrode 5 is a transfer gate electrode for performing vertical transfer, and is formed on the insulating film 4. That is, the charge transfer electrode 5 is formed above the vertical transfer channel 3 via the insulating film 4. The charge transfer electrode 5 is made of, for example, polycrystalline silicon (polysilicon).

  The antireflection film 6 is formed on the insulating film 4 and prevents reflection of light incident on the photodiode 2.

  The interlayer insulating film 16 a is formed on the charge transfer electrode 15 so as to cover the charge transfer electrode 15. For example, the interlayer insulating film 16a is a silicon oxide film.

  The light shielding film 17 is a metal film for preventing light from entering the vertical transfer channel 3 and is formed only above the charge transfer electrode 15 via the interlayer insulating film 16a. Further, the horizontal width (the horizontal length in FIG. 2) of the light shielding film 17 is shorter than the horizontal width (the horizontal length in FIG. 2) of the charge transfer electrode 15. That is, in the horizontal direction (lateral direction in FIG. 2), both end portions of the light shielding film 17 are formed on the region where the charge transfer electrode 15 is formed (inside the both end portions of the charge transfer electrode 15). Do not cover the sides.

In addition, a charge transfer pulse for driving the charge transfer electrode 15 is applied to the light shielding film 17.
The contact 18 penetrates the interlayer insulating film 16 a and electrically connects the light shielding film 17 and the charge transfer electrode 15. The contact 18 connects the light-shielding film 17 to which the corresponding charge transfer pulse is applied and the charge transfer electrode 15.

  For example, when a four-phase charge transfer pulse is used, one of the four-phase charge transfer pulses is applied to the light shielding film 17 in each column. Each of the plurality of charge transfer electrodes 15 corresponds to one of four-phase charge transfer pulses, and is connected via a contact 18 to a light shielding film 17 to which the corresponding charge transfer pulse is applied. That is, one contact 18 is formed for each of the four charge transfer electrodes 15 in each light shielding film 17.

  The interlayer insulating film 6b is formed on the interlayer insulating film 16a and the light shielding film 17, and the upper surface is flattened.

  The color filter layer 8a is formed on the interlayer insulating film 6b and transmits light of a predetermined wavelength band.

  The microlens 8 b is formed above the photodiode 2 and on the color filter layer 8 a, and collects incident light on the photodiode 2.

  Incident light collected by the microlens 8 b passes through the color filter layer 8 a and the opening 17 a of the light shielding film 17 and enters the photodiode 2.

  Here, the light shielding film 17 has a structure that does not cover the side wall of the charge transfer electrode 15. Therefore, since the opening width L1 of the light shielding film 17 and the width of the charge transfer electrode 15 can be determined independently of each other, the opening width L1 and the width of the charge transfer electrode 15 can be set to their optimum widths.

  Further, the solid-state imaging device according to the first embodiment of the present invention can be obtained in the same cell by omitting the overhanging portion of the light shielding film 7 covering the side wall of the charge transfer electrode 5 as compared with the conventional configuration shown in FIG. If it is a size, the opening area can be increased by about 1.5 times compared to the conventional configuration. Thereby, the solid-state imaging device according to the first embodiment of the present invention can increase the sensitivity characteristic by 1.5 times compared with the conventional configuration without increasing the chip area.

  Here, in the conventional configuration shown in FIG. 9, when the light shielding film 7 is formed only on the charge transfer electrode 5, the distance between the light shielding film 7 and the semiconductor substrate 1 is increased, and the light shielding film 7 is formed at the end of the light shielding film 7. Increasing smear due to obliquely incident light leakage becomes a problem.

  On the other hand, in the solid-state imaging device according to the first embodiment of the present invention, the distance t1 between the bottom surface of the light shielding film 17 and the surface of the semiconductor substrate 1 is set to be equal to or less than the conventional structure shown in FIG. Since the incident light 9d can be prevented from leaking into the vertical transfer channel 3, it is possible to prevent the smear characteristic from deteriorating.

  Specifically, in the solid-state imaging device according to Embodiment 1 of the present invention, the distance t1 between the light-shielding film 17 and the semiconductor substrate 1 is set to be 150 nm or less, which is the same as the conventional one.

  Here, the distance t1 is the sum of the film thicknesses of the insulating film 4 (gate insulating film) under the charge transfer electrode 15, the charge transfer electrode 15, and the interlayer insulating film 16a on the charge transfer electrode 15. In the solid-state imaging device according to Embodiment 1 of the present invention, the thickness of the gate insulating film 4 is the same as that of the conventional structure and is about 40 nm.

  Further, the film thickness of the interlayer insulating film 16 a on the charge transfer electrode 15 is determined from the breakdown voltage between the light shielding film 17 and the charge transfer electrode 15. Specifically, for example, when a maximum voltage of 21 V is applied to the light shielding film 17 and the charge transfer electrode 15, the breakdown voltage between the light shielding film 17 and the charge transfer electrode 15 needs to be ensured to be 5 MV / cm or more. For this reason, the film thickness of the interlayer insulating film 16a is desirably about 42 nm.

  The film thickness of the charge transfer electrode 15 is set according to the margin for forming the contact 18 and the conditions for maximizing the antireflection effect at the end of the charge transfer electrode 15. Specifically, since the polycrystalline silicon film constituting the charge transfer electrode 15 has a refractive index of about 3.0, the charge transfer electrode 15 having a film thickness of λ / 4 can be used as an antireflection film. The effect can be further enhanced.

  More specifically, the refractive index at λ = 400 nm of the polycrystalline silicon film is about 5.6, and the refractive index at λ = 700 nm is about 3.4. Therefore, in the visible light region of 400 nm to 700 nm, the polycrystalline silicon film In the case of a film, the film thickness of λ / 4 is 18 nm to 51 nm. However, since it is necessary to adjust the optimum film thickness of the polycrystalline silicon film according to the thickness of the insulating film 4 underlying the antireflection film and the thickness of the upper interlayer insulating film 16a, the film thickness of the charge transfer electrode 15 Is preferably set to 15 nm to 60 nm. If the margin for forming the contact 18 is 15 nm to 60 nm, there is no problem.

  As described above, the maximum value of the distance t1 between the bottom surface of the light shielding film 17 and the surface of the semiconductor substrate 1 is 40 + 42 + 51 = 133 nm, which is 150 nm or less.

  As described above, the solid-state imaging device according to Embodiment 1 of the present invention can suppress an increase in smear by setting the distance t1 between the light shielding film 17 and the semiconductor substrate 1 to be approximately the same as the conventional one. Thereby, since it is not necessary to use the FIT structure for reducing smear, the chip size can be reduced to about 3/4 compared with the solid-state imaging device described in Patent Document 1 using the FIT structure.

  In Patent Document 1, the distance between the light-shielding film 7 and the semiconductor substrate 1 is reduced by inclining the charge transfer electrode 5, but the resistance varies due to etching variations when the charge transfer electrode 5 is formed. In addition, there arises a problem that the distance between the light shielding film 7 and the semiconductor substrate 1 varies and the smear characteristic varies. On the other hand, in the solid-state imaging device according to the first embodiment of the present invention, the charge transfer electrode 15 is formed only by film formation, so that the resistance of the charge transfer electrode 15 is uniform and between the light shielding film 17 and the semiconductor substrate 1. The uniformity of the distance t1 can be improved.

  Further, as described above, when the thickness of the charge transfer electrode 15 is reduced, the resistance value of the charge transfer electrode 15 increases. On the other hand, in the solid-state imaging device according to Embodiment 1 of the present invention, the resistance of the wiring reaching the charge transfer electrode 15 is achieved by forming the charge transfer electrode 15 and the light shielding film 17 with a backing structure using the contact 18. The value can be reduced.

  Specifically, in the solid-state imaging device according to Embodiment 1 of the present invention, the charge transfer electrode 15 is formed of a polycrystalline silicon film, and the light shielding film 17 is formed of a metal film. Here, since the resistance of the metal film is 1/10 or less of that of polycrystalline silicon, a low resistance wiring can be realized by forming the charge transfer electrode 15 and the light shielding film 17 with a backing structure using the contact 18.

  Furthermore, by reducing the resistance value of the wiring reaching the charge transfer electrode 15, the solid-state imaging device according to Embodiment 1 of the present invention can improve the vertical transfer speed. Therefore, the solid-state imaging device according to Embodiment 1 of the present invention can suppress an increase in smear that occurs when the light shielding film 17 does not cover the charge transfer electrode 15 without using the FIT structure or the like.

  Next, a method for manufacturing the solid-state imaging device according to Embodiment 1 of the present invention will be specifically described with reference to the drawings.

  3A, 3B, and 3C are diagrams for explaining the method of manufacturing the solid-state imaging device according to Embodiment 1 of the present invention, and are cross-sectional views in the manufacturing process of the solid-state imaging device according to Embodiment 1. is there.

  First, the photodiode 2 is formed in the semiconductor substrate 1. Next, the insulating film 4 is formed on the semiconductor substrate 1, and the charge transfer electrode 15 and the antireflection film 6 c are formed on the insulating film 4. Thus, the structure shown in FIG. 3A is formed.

  Next, an interlayer insulating film 16 a is formed so as to cover the charge transfer electrode 15, and then a contact 18 and a light shielding film 17 are sequentially formed on the charge transfer electrode 15. Thus, the configuration shown in FIG. 3B is formed.

  Next, after forming a flat layer to be the interlayer insulating film 6b, a color filter layer 8a and a microlens 8b are sequentially formed. Thus, the configuration shown in FIG. 3C is formed.

(Embodiment 2)
In the solid-state imaging device according to the second embodiment of the present invention, the point where one end of the light shielding film 27 in the width direction (horizontal method) covers the side surface of the charge transfer electrode 15 is the solid-state imaging according to the first embodiment. Different from the device.

  FIG. 4 is a cross-sectional view showing the structure of the solid-state imaging device according to Embodiment 2 of the present invention. The same elements as those in FIG. 2 are denoted by the same reference numerals, and only differences will be described.

  The light shielding film 27 is a metal film for preventing light from entering the vertical transfer channel 3, and is formed above the charge transfer electrode 15. Further, in the horizontal direction (lateral direction in FIG. 4), one end of the light shielding film 17 is formed on a region where the charge transfer electrode 15 is formed (inside from one end of the charge transfer electrode 15). The other end of the light shielding film 17 is formed outside the region where the charge transfer electrode 15 is formed (outside the other end of the charge transfer electrode 15). That is, one horizontal end portion of the light shielding film 27 covers one side surface of the charge transfer electrode 15, and the other horizontal end portion of the light shielding film 27 does not cover the other side surface of the charge transfer electrode 15.

  With the above configuration, the distance between the bottom surface of the light shielding film 27 and the surface of the semiconductor substrate 1 is t2 on the side where the light shielding film 27 covers the charge transfer electrode 15, and the thickness of the charge transfer electrode 15 is larger than t1. It gets smaller. Thereby, the solid-state imaging device according to the second embodiment of the present invention can reduce smear compared to the solid-state imaging device according to the first embodiment.

  In the solid-state imaging device according to the second embodiment, the opening width L2 of the light shielding film 27 is narrower than the opening width L1 of the light shielding film 17 of the first embodiment, but the opening of the conventional solid-state imaging device shown in FIG. It becomes wider than the width L6.

  Further, in the solid-state imaging device according to Embodiment 2 of the present invention, the step of the base when the light shielding film 27 is formed can be reduced by reducing the thickness of the charge transfer electrode 15. Thereby, the processing accuracy of the light shielding film 27 can be improved.

  Further, the manufacturing method of the solid-state imaging device according to the second embodiment of the present invention is the same as the manufacturing method of the solid-state imaging device according to the first embodiment except that the pattern of the light shielding film 27 is different. To do.

(Embodiment 3)
The solid-state imaging device according to the third embodiment of the present invention is that the film thickness of the interlayer insulating film 36a on the charge transfer electrode 15 is different between the end portion and the central portion of the light shielding film 17 according to the first embodiment. Different from the imaging device.

  FIG. 5 is a cross-sectional view showing the structure of the solid-state imaging device according to Embodiment 3 of the present invention. The same elements as those in FIG. 2 are denoted by the same reference numerals, and only differences will be described.

  As shown in FIG. 5, the interlayer insulating film 36a has a film thickness h1 in a region near the end of the light shielding film 17, and a film thickness h2 thicker than the film thickness h1 in a region near the center of the light shielding film 17. Have Here, the region near the end portion of the light shielding film 17 is a region including at least the portion below the end portion of the light shielding film 17, and the region near the center portion of the light shielding film 17 is the light shielding region in the region under the light shielding film 17. This is a region other than the region near the end of the film 17.

  For example, the film thickness h1 is about 42 nm, and the film thickness h2 is about 42 to 200 nm. The film thickness h2 is preferably set to 150 nm, which is about the same as the conventional configuration.

  Thus, by increasing the film thickness h2 in the region near the center of the interlayer insulating film 36a, the wiring capacitance between the light shielding film 17 and the charge transfer electrode 15 can be reduced. As a result, the influence of the charge transfer pulse applied to the light shielding film 17 on the charge transfer electrode 15 that is not backed by the light shielding film 17 can be reduced.

  Furthermore, since the film thickness h1 of the interlayer insulating film 36a under the edge of the light shielding film 17 is the same as that of the solid-state imaging device according to the first embodiment, the bottom surface of the light shielding film 17 and the semiconductor substrate 1 at the edge of the light shielding film 17 The distance t1 from the surface is 150 nm or less as in the first embodiment.

  That is, the solid-state imaging device according to the third embodiment of the present invention can further reduce the wiring capacitance between the light shielding film 17 and the charge transfer electrode 15 while maintaining the smear reduction effect equivalent to that of the first embodiment. .

Next, a method for manufacturing the solid-state imaging device according to Embodiment 3 of the present invention will be described.
6A to 6F are diagrams for explaining a method of manufacturing the solid-state imaging device according to Embodiment 3 of the present invention, and are cross-sectional views in the manufacturing process of the solid-state imaging device according to Embodiment 3.

  First, as in the method of manufacturing the solid-state imaging device according to the first embodiment, the photodiode 2 is formed in the semiconductor substrate 1, then the insulating film 4 is formed on the semiconductor substrate 1, and then the insulating film 4, the charge transfer electrode 15 and the antireflection film 6 c are formed. As a result, the structure shown in FIG. 6A is formed.

  Next, an interlayer insulating film 40 having a flat upper surface is formed on the surface of the structure shown in FIG. 6A. Next, dry etching is performed on the selected enemy using the resist pattern 41 to remove the interlayer insulating film 40 in other regions while leaving the interlayer insulating film 40 in the central region on the charge transfer electrode 15. In the dry etching, the etching is stopped when the surface of the polycrystalline silicon (charge transfer electrode 15) is exposed. For example, the film thickness of the interlayer insulating film 40 in the central region on the charge transfer electrode 15 is about 150 nm. Thus, the structure shown in FIG. 6B is formed.

  Next, an interlayer insulating film 42 of about 42 nm corresponding to the film thickness h1 is formed on the surface of the structure shown in FIG. 6B. That is, the interlayer insulating film 42 is formed on the interlayer insulating film 40 and the exposed charge transfer electrode 15. As a result, the structure shown in FIG. 6C is formed. Here, the interlayer insulating film 40 and the interlayer insulating film 42 are a part of the interlayer insulating film 36a, and the total thickness of the interlayer insulating film 40 and the interlayer insulating film 42 corresponds to the film thickness h2.

  Next, by forming a contact hole 43 for forming the contact 18, the structure shown in FIG. 6D is formed.

  Next, the structure shown in FIG. 6E is formed by sequentially forming the contact 18 and the light shielding film 17.

  Next, after forming a flat layer to be the interlayer insulating film 6b, a color filter layer 8a and a microlens 8b are sequentially formed. Thus, the configuration shown in FIG. 6F is formed.

  Note that the formation of the interlayer insulating film 42 may be omitted by stopping the etching so as to secure a remaining film of 42 nm or more without etching the polycrystalline silicon (charge transfer electrode 15) when the interlayer insulating film 40 is formed. .

  In the description of the third embodiment, the case where the light shielding film 17 is formed only on the charge transfer electrode 15 is described as in the first embodiment. However, as in the second embodiment, the light shielding film 17 is formed. This may be applied to the case where one of the ends covers the side surface of the charge transfer electrode 15. In this case, the interlayer insulating film 36a sandwiched between the light shielding film 17 and the charge transfer electrode 15 includes at least a region having a film thickness h1 including an area below the end of the light shielding film 17 on the side that does not cover the end of the charge transfer electrode 15. A region having a film thickness h <b> 2 other than a region including the region below the end of the light shielding film 17 may be included.

  The present invention can be applied to a solid-state imaging device, and in particular, can be applied to a digital still camera, a digital video camera, a mobile phone device, and the like provided with a CCD image sensor.

It is a top view of the solid-state imaging device concerning Embodiment 1 of the present invention. It is sectional drawing of the solid-state imaging device concerning Embodiment 1 of this invention. It is sectional drawing in the manufacture process of the solid-state imaging device which concerns on Embodiment 1 of this invention. It is sectional drawing in the manufacture process of the solid-state imaging device which concerns on Embodiment 1 of this invention. It is sectional drawing in the manufacture process of the solid-state imaging device which concerns on Embodiment 1 of this invention. It is sectional drawing of the solid-state imaging device which concerns on Embodiment 2 of this invention. It is sectional drawing of the solid-state imaging device which concerns on Embodiment 3 of this invention. It is sectional drawing in the manufacture process of the solid-state imaging device which concerns on Embodiment 3 of this invention. It is sectional drawing in the manufacture process of the solid-state imaging device which concerns on Embodiment 3 of this invention. It is sectional drawing in the manufacture process of the solid-state imaging device which concerns on Embodiment 3 of this invention. It is sectional drawing in the manufacture process of the solid-state imaging device which concerns on Embodiment 3 of this invention. It is sectional drawing in the manufacture process of the solid-state imaging device which concerns on Embodiment 3 of this invention. It is sectional drawing in the manufacture process of the solid-state imaging device which concerns on Embodiment 3 of this invention. It is a figure which shows typically the structure of the conventional solid-state imaging device. It is a top view of the conventional solid-state imaging device. It is sectional drawing of the conventional solid-state imaging device. It is a figure which shows typically the structure of the solid-state imaging device of the conventional FIT structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Photodiode 3 Vertical transfer channel 4 Insulating film 5, 15 Charge transfer electrode 6a, 6b, 16a, 36a, 40, 42 Interlayer insulating film 7, 17, 27 Light shielding film 7a, 17a Opening 8a Color filter layer 8b Microlenses 9a, 9b, 9c, 9d Obliquely incident light 10 Horizontal transfer channel 11 Charge storage region 18 Contact 41 Resist pattern 43 Contact hole

Claims (8)

A semiconductor substrate;
A light receiving portion that is formed on the semiconductor substrate and converts light into signal charges;
A charge transfer channel formed on the semiconductor substrate for transferring the signal charge converted by the light receiving unit;
An insulating film formed on a surface of the semiconductor substrate;
A charge transfer electrode formed above the charge transfer channel via the insulating film;
An interlayer insulating film formed on the charge transfer electrode;
The charge transfer electrode is formed via the interlayer insulating film, and at least one end is formed on a region where the charge transfer electrode is formed in a direction perpendicular to the transfer direction of the charge transfer channel. A light shielding film;
A contact connecting the charge transfer electrode and the light shielding film;
A solid-state imaging device comprising: a lens that is formed above the light receiving unit and collects incident light on the light receiving unit. The total thickness of the insulating film under the charge transfer electrode, the charge transfer electrode, and the interlayer insulating film on the charge transfer electrode under the one end of the light shielding film is 150 nm or less. Item 2. The solid-state imaging device according to Item 1. The solid-state imaging device according to claim 1, wherein both ends of the light shielding film are formed on a region where the charge transfer electrode is formed in a direction perpendicular to a transfer direction of the charge transfer channel. In the direction perpendicular to the transfer direction of the charge transfer channel, the light shielding film has one end formed on a region where the charge transfer electrode is formed, and the other end formed by the charge transfer electrode. The solid-state imaging device according to claim 1, wherein the solid-state imaging device is formed outside a region to be formed. The interlayer insulating film sandwiched between the light-shielding film and the charge transfer electrode includes a first region having a first film thickness and a portion under the one end of the light-shielding film, and from the first film thickness. The solid-state imaging device according to claim 1, further comprising: a second region having a thin second film thickness. The solid-state imaging device according to claim 1, wherein the light shielding film is a metal film. Forming a light receiving portion for converting light into a signal charge on a semiconductor substrate;
Forming a charge transfer channel for transferring the signal charge converted by the light receiving unit on the semiconductor substrate;
Forming an insulating film on the surface of the semiconductor substrate;
Forming a charge transfer electrode above the charge transfer channel via the insulating film;
Forming an interlayer insulating film on the charge transfer electrode;
A light-shielding film in which at least one end in a direction perpendicular to the transfer direction of the charge transfer channel is formed on a region where the charge transfer electrode is formed via the interlayer insulating film above the charge transfer electrode Forming a step;
Forming a contact connecting the charge transfer electrode and the light shielding film;
Forming a lens for condensing incident light on the light receiving unit above the light receiving unit. The step of forming the interlayer insulating film includes:
Flatly forming a first interlayer insulating film that is part of the interlayer insulating film;
A second region other than the first region on the charge transfer electrode except for the first interlayer insulating film in the first region on the charge transfer electrode and not including the one end of the charge transfer electrode. Removing the first interlayer insulating film in a region;
And forming a second interlayer insulating film that is a part of the interlayer insulating film on the first interlayer insulating film in the first region and on the charge transfer electrode in the second region. The manufacturing method of the solid-state imaging device of description.

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