JP4090221B2 - Solid-state imaging device and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a solid-state imaging device using a solid-state imaging device such as a CCD as an imaging device and a method for manufacturing the same.
[0002]
[Prior art]
Conventionally, as a solid-state imaging device using a solid-state imaging device, a CCD-type imaging device using a CCD as a solid-state imaging device has been widely used.
[0003]
Hereinafter, a conventional solid-state imaging device using a CCD as a solid-state imaging device will be described.
FIG. 5 is a plan view showing a configuration of a conventional solid-state imaging device. 6 is a cross-sectional view showing a configuration of a conventional solid-state imaging device. FIG. 6A is a cross-sectional view taken along line AA ′ in FIG. 5, FIG. 6B is a cross-sectional view taken along line BB ′ in FIG. 6 (c) shows the CC ′ cross section of FIG. 5 and 6, reference numeral 21 denotes a semiconductor substrate, 22 and 22 a are diffusion layers selectively formed on the surface of the semiconductor substrate 21, and 23 is an oxide insulation formed over the entire surface of the semiconductor substrate 21 including the diffusion layer 22. A film, 24 is a first gate electrode, 25 is a second gate electrode, 26 is a light-shielding film, 27 is a transparent resin or color resin, and 28 is a lens. In addition, since the shape of the lens 28 has flattened the lower surface of each lens 28, the variation for every pixel is suppressed.
[0004]
The operation of the solid-state imaging device configured as described above will be described below.
The light from the subject is collected by the lens 28, passes through the transparent (or color) resin 27, and only the light that enters the light receiving region of the diffusion layer 22 corresponding to the opening 26 a of the light shielding film 26 is photoelectrically converted. After that, the signal charge moves to the transfer region by applying a voltage to the second gate electrode 25, and then applies a voltage to the adjacent first gate electrode 24, and then further to the adjacent second gate. By sequentially applying a voltage to the electrode 25, the inside of the transfer region diffusion layer 22a is sequentially transferred, and finally outputted from this apparatus as an electric signal having a waveform corresponding to the change in the intensity of light from the subject. The
[0005]
[Problems to be solved by the invention]
However, in the conventional solid-state imaging device as described above, the gate electrode is composed of two layers of the first gate electrode 24 and the second gate electrode 25 as shown in the AA ′ cross-sectional view of FIG. Since the polysilicon is formed in an overlapping structure, there is an overlap of the two layers of gate electrodes in the portion adjacent to the opening 26a of the light shielding film 26 which becomes the light receiving region of the diffusion layer 22.
[0006]
Therefore, the light-shielding film 26 is increased by the thickness of the gate electrode for one layer at the overlapping portion, so that the amount of so-called “scratch” that obstructs the light collected by the lens 28 increases, However, the pixel has a problem in that the sensitivity is significantly lowered.
[0007]
The present invention solves the above-described conventional problems, and even in a miniaturized pixel, it is possible to improve the sensitivity of the pixel by increasing the light collection efficiency of the lens, and to obtain a stable and highly sensitive pixel. Provided are a solid-state imaging device and a manufacturing method thereof.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, a solid-state imaging device according to the present invention has a plurality of light receiving regions formed on a semiconductor substrate, and the signal charges obtained by photoelectrically converting incident light to the light receiving regions are A waveform that finally changes in accordance with the intensity of the incident light while moving the transfer portion region in the semiconductor substrate by sequentially applying a voltage to the first electrode and the second electrode formed in the vicinity. In the solid-state imaging device that outputs the electrical signal, the first electrode is formed on the semiconductor substrate in a state of being insulated from the semiconductor substrate by an insulating film formed on the semiconductor substrate, and the second electrode, the first electrode and electrically insulated state, wherein formed on a semiconductor substrate, the first electrode and the second electrode, between the light receiving region in at least the transfer direction Then, the second electrode is the Is on the first electrode, between the respective light-receiving regions in the direction perpendicular to at least the transfer direction, said on the first electrode, characterized by being configured such that there are no said second electrode.
[0009]
In addition, the solid-state imaging device manufacturing method of the present invention has a plurality of light receiving regions formed on a semiconductor substrate, and forms signal charges obtained by photoelectrically converting incident light to the light receiving regions in the vicinity of the light receiving regions. An electric signal having a waveform that finally changes in accordance with the intensity of the incident light while moving the transfer region in the semiconductor substrate by sequentially applying a voltage to the first electrode and the second electrode. A method of manufacturing a solid-state imaging device that outputs an insulating film on the semiconductor substrate; a step of forming the first electrode on the semiconductor substrate through the insulating film; Forming a second electrode on the semiconductor substrate and the first electrode in a state of being electrically insulated from the first electrode; and a portion of the second electrode overlapping the first electrode At least in a direction perpendicular to the transfer direction. Kicking is characterized in that the method comprising the step of removing the portion between the respective light-receiving regions.
[0010]
As described above, the overlap of the gate electrode portion adjacent to the opening of the light shielding film is eliminated, the height of the light shielding film at that portion is suppressed, and the vignetting is reduced with respect to the light collected by the lens. As a result, it is possible to improve the light collection efficiency of the lens.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The solid-state imaging device according to claim 1 of the present invention has a plurality of light receiving regions formed on a semiconductor substrate, and a signal charge obtained by photoelectrically converting incident light to the light receiving region is placed in the vicinity of the light receiving region. A voltage is applied to the formed first electrode and second electrode in sequence to move the transfer portion region in the semiconductor substrate, and finally, an electric wave having a waveform that changes according to the intensity of the incident light. In the solid-state imaging device that outputs a signal, the first electrode is formed on the semiconductor substrate while being insulated from the semiconductor substrate by an insulating film formed on the semiconductor substrate, and the second electrode the electrodes, the first electrode and electrically insulated state, formed on the semiconductor substrate, the first electrode and the second electrode, between the respective light-receiving regions in at least the transfer direction, The second electrode is the first electrode Is above, between the respective light-receiving regions in the direction perpendicular to at least the transfer direction, said on the first electrode configured to no the second electrode.
[0012]
The solid-state imaging device according to claim 2 is the solid-state imaging device according to claim 1, wherein a buried electrode functioning as a part of the first electrode is provided between the light receiving regions in the transfer direction. It is configured to be embedded inside.
The method for manufacturing a solid-state imaging device according to claim 3 has a plurality of light receiving regions formed on a semiconductor substrate, and a signal charge obtained by photoelectrically converting incident light to the light receiving region is placed in the vicinity of the light receiving region. A voltage is applied to the formed first electrode and second electrode in sequence to move the transfer portion region in the semiconductor substrate, and finally, an electric wave having a waveform that changes according to the intensity of the incident light. A method of manufacturing a solid-state imaging device that outputs a signal, the step of forming an insulating film on the semiconductor substrate, the step of forming the first electrode on the semiconductor substrate via the insulating film, Forming a second electrode on the semiconductor substrate and the first electrode in a state of being electrically insulated from the first electrode, and a portion overlapping the first electrode of the second electrode Direction at least orthogonal to the transfer direction A method comprising the step of removing the portions between respective light receiving areas definitive.
[0013]
The method for manufacturing a solid-state imaging device according to claim 4 has a plurality of light receiving regions formed on a semiconductor substrate, and a signal charge obtained by photoelectrically converting light incident on the light receiving region is placed in the vicinity of the light receiving region. A voltage is applied to the formed first electrode and second electrode in sequence to move the transfer portion region in the semiconductor substrate, and finally, an electric wave having a waveform that changes according to the intensity of the incident light. A method of manufacturing a solid-state imaging device that outputs a signal, the step of forming a buried electrode functioning as a part of the first electrode in the semiconductor substrate between light receiving regions in the transfer direction, and the semiconductor Forming a first insulating film on the substrate; forming a hole in the insulating film on the embedded electrode; and on the first insulating film so as to be connected to the embedded electrode through the hole. Said first Forming a first electrode on the substrate that functions as a part of the electrode; forming a second insulating film on the first electrode; and forming an electrode material so as to cover the first electrode a step of the steps of the electrode material to remove electrode material on the first electrode by flattening to form the second electrode and the remaining said electrode material between the first electrode A method consisting of
[0015]
According to these configurations and methods, the overlap of the gate electrode portion adjacent to the opening of the light shielding film is eliminated, the height of the light shielding film at that portion is suppressed, and the light collected by the lens is By reducing the vignetting, it is possible to improve the light collection efficiency of the lens.
[0016]
Hereinafter, a solid-state imaging device and a manufacturing method thereof according to an embodiment of the present invention will be specifically described with reference to the drawings.
(Embodiment 1)
A solid-state imaging device and a manufacturing method thereof according to Embodiment 1 of the present invention will be described.
[0017]
FIG. 1 is a plan view showing the configuration of the solid-state imaging device according to the first embodiment. 2 is a cross-sectional view illustrating the configuration of the solid-state imaging device according to the first embodiment. FIG. 2A is a cross-sectional view taken along the line AA ′ in FIG. 1, and FIG. 'Cross section, FIG. 2 (c) shows a CC' section in FIG. 1 and FIG. 2, 1 is a semiconductor substrate, 2 is a diffusion layer formed selectively on the surface of the semiconductor substrate 1, and 3 is an oxide insulation formed over the entire surface of the semiconductor substrate 1 including the diffusion layer 2. 4 is a first gate electrode, 5 is a second gate electrode, 6 is a light-shielding film, 7 is a transparent resin (or color resin), and 8 is a lens.
[0018]
A method for manufacturing the solid-state imaging device configured as described above will be described below.
FIG. 3 is a manufacturing process diagram illustrating a method of manufacturing the solid-state imaging device according to the first embodiment. After the first gate electrode 4 and the second gate electrode 5 are formed on the semiconductor substrate 1, as shown in step (1) of FIG. As shown in step (2) of 3 (c), a resist pattern is selectively formed so that a portion including the overlapping portion of the first and second gate electrodes 4 and 5 is opened.
[0019]
Next, as shown in step (3) in FIG. 3C, the portion including the overlapping portion of the gate electrodes 4 and 5 is removed by isotropic etching. By performing the etching amount at this time in the range of 140% to 200% of the film thickness of the second gate electrode 5, a desired shape can be obtained. Thereafter, as shown in step (4) of FIG. 3C, a normal interlayer insulating film and a light shielding film 6 are formed.
[0020]
Advantages of the solid-state imaging device having the above-described configuration and manufacturing method will be described below.
As shown in the AA ′ cross-sectional view of FIG. 2A, the light condensing rate of the lens 8 can be improved by suppressing the squeezing in the region adjacent to the opening 6a. In particular, when the diaphragm on the camera side is opened, the effect is remarkable because the oblique light component increases in the light incident on the imaging surface of the imaging device. In order to compare the loss ratio with the conventional one, the ratio of the light-shielding region for one layer of the gate electrode to the pixels in the 3 μm pitch is secured at 40% or more compared to the conventional 20%. it can.
[0021]
As described above, by configuring the solid-state imaging device as an imaging device, the gate electrode portion adjacent to the opening 6a of the light shielding film 6 is not overlapped, and the height of the light shielding film 6 at that portion is increased. It is possible to improve the light condensing efficiency of the lens 8 by suppressing and reducing the fluctuation of the light collected by the lens 9.
[0022]
As a result, the light collection efficiency of the lens 8 can be increased to improve the sensitivity of the pixels, and an imaging device that can stably obtain highly sensitive pixels can be realized. This effect is particularly prominent in a fine pixel.
[0023]
In the first embodiment, the overlap with the first gate electrode 4 in the opening 6a of the second gate electrode 5 is all removed, but only the portion adjacent to the opening 6a may be removed. Good.
[0024]
In the first embodiment, after the first gate electrode 4 is formed, polysilicon to be the second gate electrode 5 is grown, and this polysilicon is planarized by CMP to form the second gate electrode 5. A wiring for connecting these second gate electrodes 5 later may be formed on the first gate electrode 4.
(Embodiment 2)
A solid-state imaging device and a manufacturing method thereof according to Embodiment 2 of the present invention will be described.
[0025]
4A and 4B are a plan view and a cross-sectional view showing the configuration and manufacturing method of the solid-state imaging device according to the second embodiment. 4 is omitted because it is the same as the conventional structure, but similarly to FIG. 1 and FIG. 2, the diffusion layer 2 selectively formed on the surface of the semiconductor substrate 1, and the diffusion layer 2, an oxide insulating film 3 formed over the entire surface of the semiconductor substrate 1 including 2. Differences from FIG. 1 will be described below. In FIG. 4, 9 is a buried gate electrode buried in the semiconductor substrate 1, and 10 is a contact hole for electrically connecting the buried gate electrode 9 and the first gate electrode 4 formed on the oxide insulating film 3. Reference numeral 5 denotes a second gate electrode, and reference numeral 6 denotes a light shielding film.
[0026]
A method for manufacturing the solid-state imaging device configured as described above will be described below.
As shown in the plan view of FIG. 4A, the DD ′ cross-sectional view of FIG. 4B, and the CC ′ cross-sectional view of FIG. First, similarly to FIG. 2, after selectively forming the diffusion layer 2 on the semiconductor substrate 1, the buried gate electrode 9 is formed, and the oxide insulating film 3 is further formed. Thereafter, contact holes 10 are formed.
[0027]
Next, as shown in step (1) of FIG. 4D, after the first gate electrode 4 is formed on the semiconductor substrate 1, polysilicon is grown. Then, as shown in step (2) in FIG. 4 (d), the polysilicon is planarized by CMP to form the second gate electrode 5 with polysilicon, and then in step (3) in FIG. 4 (d). As shown in FIG. 2, a normal light shielding film 6, a transparent resin (or color resin), and a lens are formed.
[0028]
Advantages of the solid-state imaging device having the above-described configuration and manufacturing method will be described below.
As shown in the DD ′ cross-sectional view of FIG. 4B and the CC ′ cross-sectional view of FIG. 4C, the light-shielding film 6 is eliminated by eliminating all overlapping of the gate electrodes adjacent to the opening 6a. The height is suppressed without increasing the plane area of the connecting portion even in the portion (DD ′ cross section) where the gate electrodes arranged two-dimensionally are connected. Therefore, since the opening 6a can be expanded not only in the Y direction but also in the X direction, the light collection efficiency of the lens can be further improved.
[0029]
As described above, by configuring the solid-state imaging device as an imaging device, the gate electrode portion adjacent to the opening 6a of the light shielding film 6 is not overlapped, and the height of the light shielding film 6 at that portion is increased. It is possible to improve the condensing efficiency of the lens by suppressing and reducing the fluctuation of the light collected by the lens.
[0030]
As a result, it is possible to improve the sensitivity of the pixels by increasing the light collection efficiency of the lens, and it is possible to realize an imaging device that can stably obtain highly sensitive pixels. This effect is particularly prominent in a fine pixel.
[0031]
【The invention's effect】
As described above, according to the present invention, the overlap of the gate electrode portion adjacent to the opening of the light shielding film is eliminated, the height of the light shielding film at that portion is suppressed, and the light collected by the lens is reduced. By reducing the vignetting, it is possible to improve the light collection efficiency of the lens.
[0032]
Therefore, even in a miniaturized pixel, it is possible to improve the sensitivity of the pixel by increasing the light collection efficiency of the lens, and it is possible to realize an imaging device that can stably obtain a highly sensitive pixel.
[Brief description of the drawings]
FIG. 1 is a plan view showing the configuration of a solid-state imaging device according to Embodiment 1 of the present invention; FIG. 2 is a cross-sectional view showing the configuration of the solid-state imaging device according to Embodiment 1; Manufacturing process diagram showing manufacturing method of solid-state imaging device FIG. 4 is a plan view and cross-sectional view showing the configuration of the solid-state imaging device according to Embodiment 2 of the present invention, and manufacturing process diagram showing the manufacturing method. FIG. 6 is a plan view showing the configuration of the imaging device. FIG. 6 is a cross-sectional view showing the configuration of the solid-state imaging device of the conventional example.
1, 21 Semiconductor substrate 2, 22 Diffusion layer 3, 23 Oxide insulating film 4, 24 First gate electrode 5, 25 Second gate electrode 6, 26 Light shielding film 7, 27 Transparent resin (or color resin)
8, 28 Lens 9 Embedded gate electrode 10 Contact hole

Claims (4)

  A plurality of light receiving regions formed on the semiconductor substrate, and signal charges obtained by photoelectric conversion of light incident on the light receiving regions are sequentially applied to the first electrode and the second electrode formed in the vicinity of the light receiving region. In the solid-state imaging device that outputs an electric signal having a waveform that finally changes in accordance with the intensity of the incident light while applying a voltage to move the transfer portion region in the semiconductor substrate, the first electrode Is formed on the semiconductor substrate while being insulated from the semiconductor substrate by an insulating film formed on the semiconductor substrate, and the second electrode is electrically insulated from the first electrode. The first electrode and the second electrode are formed on the semiconductor substrate, and at least between the light receiving regions in the transfer direction, the second electrode is placed on the first electrode. Yes, at least orthogonal to the transfer direction Between each of the light receiving region in that direction, the solid-state imaging device, characterized in that configured so as not to the second electrode on the first electrode.   2. The solid-state imaging according to claim 1, wherein a buried electrode functioning as a part of the first electrode is buried in the semiconductor substrate between the light receiving regions in the transfer direction. apparatus. A plurality of light receiving regions formed on a semiconductor substrate, and signal charges obtained by photoelectric conversion of light incident on the light receiving regions are sequentially applied to a first electrode and a second electrode formed in the vicinity of the light receiving region. A method of manufacturing a solid-state imaging device that outputs an electric signal having a waveform that finally changes in accordance with the intensity of the incident light while applying a voltage and moving a transfer unit region in the semiconductor substrate, Forming an insulating film on the semiconductor substrate; forming the first electrode on the semiconductor substrate through the insulating film; and electrically connecting the second electrode to the first electrode. In the insulated state, each of the light receiving processes in the direction orthogonal to the transfer direction in the step of forming on the semiconductor substrate and the first electrode and the portion of the second electrode overlapping the first electrode removing the portion between regions Method for manufacturing a solid-state imaging device comprising a. A plurality of light receiving regions formed on a semiconductor substrate, and signal charges obtained by photoelectric conversion of light incident on the light receiving regions are sequentially applied to a first electrode and a second electrode formed in the vicinity of the light receiving region. A method of manufacturing a solid-state imaging device that outputs an electric signal having a waveform that finally changes in accordance with the intensity of the incident light while applying a voltage and moving a transfer unit region in the semiconductor substrate, Forming a buried electrode functioning as a part of the first electrode in the semiconductor substrate between the light receiving regions in the transfer direction; forming a first insulating film on the semiconductor substrate; Forming a hole in the insulating film on the buried electrode; and on a substrate functioning as a part of the first electrode on the first insulating film so as to be connected to the buried electrode through the hole. The first electrode A step of forming, a step of forming a second insulating film on the first electrode, forming an electrode material so as to cover said first electrode, said by planarizing the electrode material the electrode material on the first electrode is removed, the manufacturing method of the first said electrode material between the electrodes and remaining in the solid-state imaging device comprising the step of forming the second electrode.

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