JPH11177073A - Solid-state image pickup element with on-chip microlens and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid-state image pickup element with an on-chip micro lens which can increase the effective numerical aperture of solid-state pickup element and converge efficiently for such an exposure control sensor that detect the change of quantity of light entering directly the solid-state pickup element on a real-time basis. SOLUTION: An ordinary picture element 1A not adjacent to a picture element 2A having the aperture 2 of a second photoelectric conversion part is provided with a large standard microlens 3 for converging to the aperture 1 of a first photoelectric conversion part. The picture element 2A and the picture element 1A just above it are provided with small microlenses 4 to avoid the aperture 2 of the second photoelectric conversion part and converge to the first photoelectric conversion part. No microlens to converge to the first photoelectric conversion part is provided above the aperture 2 of the second photoelectric conversion part, so that the entry of light into the second photoelectric conversion part is hardly prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state imaging device with an on-chip microlens and a method for manufacturing the same, and more particularly, to a solid-state imaging device having at least one pixel having first and second photoelectric conversion units. The photoelectric conversion unit 2 relates to a solid-state imaging device that transmits signal outputs independent of each other in accordance with the amount of incident light, and has an on-chip microlens.

[0002]

2. Description of the Related Art In recent years, the number of pixels in a solid-state imaging device has been increased, and the pixel size has been reduced. Along with that, CCD
(Charge-Coupled Device) etc., the light-receiving surface occupies the whole pixel because there are structural areas other than the photoelectric conversion part, such as the charge transfer part and the amplifying transistor in the amplifying solid-state imaging device. Area ratio tends to decrease. Therefore, a technology has been developed in which a microlens is formed directly above the light receiving surface to efficiently collect incident light on the light receiving surface and increase the effective aperture ratio.
No. 64325. In this type of solid-state imaging device, a region other than the photodiode serving as a photoelectric conversion unit is shielded from light by a light-shielding film formed on the device, and only information regarding light incident on the photoelectric conversion unit within a predetermined exposure time is provided. Is output to the outside of the element.

FIG. 14 is a view showing the structure of a CCD which is a conventional solid-state image pickup device with a microlens. FIG. 14 (a) is a plan view, and FIG. Is being done. In FIG. 14, 1400 is a CCD unit pixel, 1401 is a vertical CCD electrode, 1402 is a photodiode,
1403 is a micro lens, 1404 is an Al light shielding film, 1405 is an N-type semiconductor region of a photodiode, 1406 is a P-type semiconductor region of a photodiode, 1407 is an N-type semiconductor region of a vertical CCD, and 1408 is a P-type semiconductor region of a vertical CCD. It is.

The light incident from the outside is reflected by the micro lens 14.
Since the light is condensed on the photodiode 1402 in 03, the area ratio of the light receiving surface is apparently improved.

[0005] In the solid-state imaging device as described above, an image is taken in a predetermined exposure time. However, in this case, if the amount of incident light changes abruptly from an assumed value within this exposure time, optical information cannot be read with an optimal exposure amount. Therefore, generally, a mechanical shutter is arranged separately from the solid-state imaging device, and the timing of opening and closing the shutter is controlled to adjust the amount of incident light. In this case, usually, an exposure control sensor capable of monitoring a change in the amount of incident light during exposure is attached.

[0006]

As a method of monitoring a change in the amount of incident light during exposure, the present applicant has
A system in which an exposure control sensor is arranged in an optical system of a solid-state imaging device to monitor a part of incident light of the solid-state imaging device was invented, and a patent application was filed as Japanese Patent Application No. 9-248435.
FIG. 15 shows a schematic configuration diagram thereof.

In FIG. 15, a photoelectric conversion element 200 is
The signal charge from the photodiode 201, the junction type electric field control transistor JFET,
A transfer transistor Q _TG to be supplied to the gate region of the FET and a reset transistor _QRSG are provided. I
_bias is a bias constant current, 291 is a sample and hold circuit, and 292 is a difference processing circuit.

The most significant feature of the first invention of the application is that the light-shielding film that normally covers the upper part of the JEFT is removed so that light is incident on the gate region of the JFET. That is, signal charges are generated according to light. That is, the gate region of the JFET serves as a second light receiving element different from the photodiode 201. The signal charge from the gate region is
The signal charge from 01 is individually or added thereto, and is sent from the source of the JFET to the signal detection circuit 290 as an electric signal V _OUT .

The greatest feature of the second invention of the application is that light is incident on the main electrode (reset drain) region of the resetting transistor _QRSG , and the reset drain region responds to incident light. To generate signal charges. This signal charge is taken out by another electronic circuit not shown in FIG. That is, the reset drain is a second light receiving element different from the photodiode 201.

By using such a solid-state imaging device of the invention of the prior application, an automatic shutter system can be configured by using the second light receiving element as a sensor for the amount of incident light during exposure. Also, this reset drain is used as a second light receiving element,
The gate region of the JFET may be a third light receiving element to form a pixel having three light receiving portions.

Although the invention of the prior application has such remarkable features, recent image pickup devices tend to have a larger number of pixels and a lower aperture ratio of each pixel. Had disadvantageous concerns.

The present invention has been made in order to solve such a problem. As in the invention according to the above-mentioned Japanese Patent Application No. 9-248435, at least one pixel has a first
And a second photoelectric conversion unit, wherein the first and second photoelectric conversion units optimally design a microlens in a solid-state imaging device that sends out signal outputs independent of each other according to the amount of incident light. Includes an on-chip microlens that increases the effective aperture ratio of the solid-state image sensor and efficiently condenses it on an exposure control sensor that detects changes in the amount of light that is directly incident on the solid-state image sensor in real time, and allows you to shoot with the optimal amount of exposure It is an object to provide a solid-state imaging device and a method for manufacturing the same.

[0013]

According to a first aspect of the present invention, at least one pixel has first and second photoelectric conversion units for at least one pixel. Is a solid-state imaging device that sends out signal outputs independent of each other in accordance with the amount of incident light. For a pixel having a second photoelectric conversion unit, an on-chip microcontroller is provided in a region immediately above the second photoelectric conversion unit. An on-chip microlens for condensing light on the first photoelectric conversion unit is formed in the other area without forming a lens, and the first photoelectric conversion unit is used for a pixel having no second photoelectric conversion unit. A solid-state imaging device with an on-chip microlens, wherein an on-chip microlens for condensing light is formed over substantially the entire pixel area of the effective light receiving area.

Among the pixels of the solid-state image pickup device, there are pixels used for correcting dark current and reference potential by shielding light, and are called dummy black, optical black, and the like. Since such a pixel does not have an effective light receiving area, it is not always necessary to form an on-chip microlens on such a pixel. Of course, on account of the manufacturing process, an on-chip micro lens may be provided on these pixels.

Further, as the pixel becomes farther from the center of the image sensor, the incident light becomes obliquely incident, so that the focus of the microlens shifts from the center of the photoelectric conversion unit toward the peripheral portion of the image sensor. It is conceivable that so-called shading may occur, but in such a case, the center of the microlens is shifted from the center of the photoelectric conversion unit to reduce the sensitivity unevenness of the pixels around the image sensor, thereby correcting the sensitivity. This means can also be applied to the case where

According to this means, it is possible to efficiently light the second photoelectric conversion unit without reducing the effective aperture ratio of the first photoelectric conversion unit.

A second means for solving the above-mentioned problems is as follows:
A solid-state imaging device having first and second photoelectric conversion units for at least one pixel, wherein the first and second photoelectric conversion units transmit signal outputs independent of each other according to the amount of incident light; The on-chip microlenses in all effective pixels are provided in substantially the same location in each pixel so as to converge on the first photoelectric conversion unit, and each on-chip microlens is provided in the second photoelectric conversion unit. A solid-state imaging device with an on-chip micro lens, wherein the pixel having the photoelectric conversion unit has a shape such that an on-chip micro lens is not formed in a region immediately above the second photoelectric conversion unit. It is.

Here, "all effective pixels" are all pixels used for detecting light, excluding the dummy black and optical black. Therefore, it is not always necessary to form the on-chip microlenses on the elements that are assumed to be dummy black and optical black. Also, “substantially the same shape” and “substantially the same place”
This means that irregularities in shape and a displacement of the position, such as a manufacturing error, are allowed.

According to this means, the shape of the on-chip microlens for condensing light on the first photoelectric conversion unit is the same for all pixels. Therefore, although the effective aperture ratio of the first photoelectric conversion unit is slightly lower than that of the first means, there is no difference in the effective aperture ratios of the first photoelectric conversion units of all the pixels. There is no need to do it. In addition, it is possible to efficiently light the second photoelectric conversion unit.

A third means for solving the above-mentioned problem is as follows.
A solid-state imaging device having first and second photoelectric conversion units for at least one pixel, wherein the first and second photoelectric conversion units transmit signal outputs independent of each other according to the amount of incident light; A solid-state imaging device with an on-chip microlens, wherein the on-chip microlens is removed only in a region immediately above the second photoelectric conversion unit.

According to this means, it is also possible to efficiently emit light to the second photoelectric conversion unit without lowering the effective aperture ratio of the first photoelectric conversion unit. Further, in each of the above means, the microlens can be formed in a region where the microlens could not be formed, and the effective aperture ratio of that portion can be increased.

A fourth means for solving the above problem is as follows.
A solid-state imaging device having first and second photoelectric conversion units for at least one pixel, wherein the first and second photoelectric conversion units transmit signal outputs independent of each other according to the amount of incident light; The on-chip microlenses in all the effective pixels are provided in substantially the same location in each pixel so as to converge on the first photoelectric conversion unit, and the shape of each on-chip microlens is (2) A solid-state imaging device with an on-chip microlens having a shape obtained by removing the on-chip microlens in a region just above the photoelectric conversion unit (Claim 4).

The meanings of "all effective pixels", "substantially the same shape", and "substantially the same place" are the same as those described in the description of the second means.

According to this means, the shape of the on-chip micro lens for condensing light on the first photoelectric conversion unit is the same for all pixels. Therefore, although the effective aperture ratio of the first photoelectric conversion unit is slightly lower than that of the third means, there is no difference in the effective aperture ratios of the first photoelectric conversion units of all the pixels. You do not need to do this.

A fifth means for solving the above problem is as follows.
The third means or the fourth means, wherein a reflective film is formed on a side wall of the hole from which the on-chip microlens has been removed (claim 5).

According to this means, the light condensed on the first photoelectric conversion unit is reflected by the reflection film and does not enter the second photoelectric conversion unit. Conversely, light that enters the second photoelectric conversion unit is reflected by the reflection film and does not enter the first photoelectric conversion unit. Therefore, crosstalk between light incident on the first photoelectric conversion unit and light incident on the second photoelectric conversion unit can be prevented.

A sixth means for solving the above-mentioned problem is:
The fifth means, wherein the reflection film is an Al film (Claim 6).

The Al film is ideal as a reflective film and can be formed by a technique used in a process of manufacturing a solid-state imaging device such as vapor deposition and anisotropic etching, so that the manufacturing method is simple. Becomes

[0029] A seventh means for solving the above problem is as follows.
In any one of the first means to the sixth means, the on-chip microlens for condensing light on the first photoelectric conversion unit is a cylindrical lens, and the cylindrical lens of adjacent pixels is a cylindrical axis. It is characterized by being connected in directions and not separated.

According to this means, the on-chip micro lenses of a plurality of pixels can be formed by one cylindrical lens. Therefore, there is no need to manage the separation width or shape in the direction in which the on-chip microlenses are connected, and the process for forming the on-chip microlenses can be simplified.

An eighth means for solving the above-mentioned problem is as follows.
An on-chip microlens lens according to any one of the first means to the seventh means, wherein the on-chip microlens lens is formed in a region immediately above the second photoelectric conversion unit so as to converge light on the first photoelectric conversion unit. In addition to the above, an on-chip microlens for condensing light on the second photoelectric conversion unit is additionally formed (claim 8).

As a result, the effective aperture ratio of the second photoelectric conversion unit is increased, and even when imaging is performed with a small amount of light,
The amount of light can be monitored and the optimal shutter speed can be set.

A ninth means for solving the above-mentioned problems is as follows:
A first, second, and third photoelectric conversion units for at least one pixel, wherein each photoelectric conversion unit is a solid-state imaging device that sends signal outputs independent of each other according to the amount of incident light; An on-chip microlens for condensing light on each light-receiving surface is formed over substantially the entire pixel area of the effective light-receiving area on the light-receiving surface of the photoelectric conversion unit. Solid-state imaging device. (Claim 9).

According to this means, since the on-chip micro lens is provided for each photoelectric conversion unit, the effective aperture ratio of each photoelectric conversion unit can be increased.

A tenth means for solving the above-mentioned problem has a first and a second photoelectric conversion unit for at least one pixel, and the first and the second photoelectric conversion units are adapted to reduce the amount of incident light. A solid-state image pickup device having an on-chip microlens that forms only an on-chip microlens for condensing light on a second photoelectric conversion unit. (Claim 1
0).

According to this means, a large on-chip microlens can be formed on the second photoelectric conversion section. Therefore, although the effective aperture ratio of the first photoelectric conversion unit is reduced, the effective aperture ratio of the second photoelectric conversion unit can be increased, and the effective aperture ratio of the second photoelectric conversion unit can be relatively freely set. Can be designed.

An eleventh means for solving the above-mentioned problem is any one of the first means, the third means, and the eighth means, wherein a signal from the first photoelectric conversion unit is converted into a signal. A solid-state image pickup device with an on-chip micro lens, wherein a means for correcting based on the effective aperture ratio and adjusting the sensitivity of each pixel is provided.

According to this means, the signal from each first element can be corrected based on the effective aperture ratio according to the shape of the on-chip micro lens provided in each element. Therefore, even when the effective aperture ratio of the first element is different between pixels, it is possible to obtain an image output without unevenness in sensitivity among the pixels.

A twelfth means for solving the above-mentioned problems is as follows:
A method of manufacturing a solid-state imaging device with an on-chip microlens according to the sixth means, wherein a microlens is formed on an upper portion of a solid-state imaging device main body, and an area portion immediately above a second photoelectric conversion unit is formed by photolithography. The hole is removed by removing the on-chip micro lens, an Al film is deposited on the entire surface of the hole by Al sputtering, and thereafter, only the Al film on the side wall of the hole is left by anisotropic etching by RIE. This is a method for manufacturing a solid-state imaging device with an on-chip microlens (claim 12).

According to this means, it is possible to manufacture the solid-state image pickup device with the on-chip microlens as the sixth means in the same steps as those for manufacturing the solid-state image pickup device.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, FIG. 1 shows a schematic diagram of a planar structure of a normal (conventional type) unit pixel of an amplification type solid-state imaging device. In FIG. 1, reference numeral 100 denotes a buried photodiode (hereinafter simply referred to as BPD) serving as a photoelectric conversion unit, and 101 denotes a junction field effect transistor (hereinafter simply referred to as JF) as an output unit.
Reference numeral 102 denotes a main electrode region (reset drain, hereinafter simply referred to as RSD) of a reset transistor for controlling the potential of the control electrode of the JFET 101. Further, a transfer gate (hereinafter, simply referred to as TG) 103 serving as a transfer portion between the BPD 100 and the JFET 101.
However, between the JFET 101 and the RSD 102, a control electrode (hereinafter simply referred to as RSG) 1 of a resetting transistor is provided.
04 is formed.

The RSD 102 is connected to the second layer aluminum through the through hole 105, and the RSD electrode 106 formed of the second layer aluminum also covers the area of the JFET 101 and the RSD 102, also serving as a light shield. Therefore, BPD10
The structure is such that an opening is provided only in one region.
Reference numeral 107 denotes a source electrode of the JFET.

FIG. 2 is a schematic diagram of a planar structure of a unit pixel for monitoring the amount of incident light in real time during exposure by TTL light control. The basic element structure is the same as FIG.
The difference is the part of RSD102,
The point is that there is no contact with the D electrode 106 and there is an opening 108 of the RSD electrode 106 right above the RSD 102. R
The SD 102 and the semiconductor region thereunder are always reverse-biased, and the RSD 102 functions as a photodiode.
As a result, the RSD electrode 106 outputs a photocurrent due to the signal charge generated in accordance with the light incident from the opening 108 to monitor the amount of incident light. That is, RSD1
The photodiode 02 functions as a second photoelectric conversion unit. (The BPD 101 is a first photoelectric conversion unit.) The present invention relates to a solid-state imaging device in which unit pixels as shown in FIG. 1 and unit pixels as shown in FIG. 2 coexist.

(Embodiment 1) FIG. 3 is a schematic view of a first embodiment of the present invention. In the present embodiment, a second photoelectric conversion unit (RS in FIG. 2) corresponding to FIG.
A unit pixel (corresponding to D opening 108) (2A in the figure)
Are arranged in a two-dimensional matrix, around which a conventional unit pixel (1A in the figure) without a second photoelectric conversion unit, corresponding to FIG. 1, is arranged. FIG. 3 is an enlarged schematic diagram of one unit pixel 2A and its surrounding unit pixels 1A.

In FIG. 3, reference numeral 1 denotes an opening on the first photoelectric conversion unit, and 2 denotes an opening on the second photoelectric conversion unit. Reference numeral 3 denotes a standard on-chip microlens for a conventional pixel (1A), and reference numeral 4 denotes a pixel (2A) having a second photoelectric conversion unit.
2 is an on-chip micro lens for a first photoelectric conversion unit. (Hereinafter, the on-chip micro lens may be simply referred to as a micro lens.) Micro lens 4
Is also provided in the pixel 1A above the pixel 2A. That is, the standard microlens 3 is not provided in the pixel 1A. If the standard microlens 3 is provided here, it will cover the opening 2 on the second photoelectric conversion unit.

In this embodiment, the separation width between adjacent microlenses 3 is 0.2 μm in both the horizontal and vertical directions. For the micro lens 4, the horizontal separation width is 0.
In the vertical direction, the separation width is large so as to avoid the opening 2 on the second photoelectric conversion unit.
The size is reduced so as to converge on the first photoelectric conversion unit. Each of the microlenses 3 and 4 uses a dome-shaped lens (toric surface) to increase the covering area as much as possible to increase the effective aperture ratio of the pixel. The lenses are arranged so that their center points coincide.

In this embodiment, since the microlens 4 for condensing light on the first photoelectric conversion unit is provided so as to avoid the opening 2 on the second photoelectric conversion unit, Light incident on the photoelectric conversion unit is not obstructed by the microlens that converges on the first photoelectric conversion unit. In the pixel 1A that is not close to the pixel 2A, a large standard microlens 3 is used.

As a result, the solid-state imaging device has a function of monitoring the amount of incident light during exposure, without reducing the effective aperture ratio of each pixel and efficiently allowing light to enter the opening on the second photoelectric conversion unit. At the same time as increasing the effective aperture ratio of the element, it becomes possible to monitor the amount of incident light. The on-chip micro lens used in the present invention may be a hemispherical lens or a cylindrical lens.

(Embodiment 2) FIG. 4 is a schematic view of a second embodiment of the present invention. In the present embodiment, a second photoelectric conversion unit (RS in FIG. 2) corresponding to FIG.
Unit pixel with D opening 102) (2A in the figure)
Are arranged in a two-dimensional matrix, around which a conventional unit pixel (1A in the figure) without a second photoelectric conversion unit, corresponding to FIG. 1, is arranged. FIG. 4 is an enlarged schematic view of one unit pixel 2A and its surrounding unit pixels 1A. In the following drawings, the same reference numerals are given to the components shown in the preceding drawings, and description thereof will be omitted.

In FIG. 4, reference numeral 5 denotes a microlens provided on the first photoelectric conversion unit. Micro lens 5
Is for condensing light on the first photoelectric conversion unit,
This is the same as the microlens 4 in FIG. 3 in the first embodiment. That is, the horizontal separation width is 0.2 μm,
In the vertical direction, the separation width is large so as to avoid the opening on the second photoelectric conversion unit, and the size is small.

The microlens 5 uses a dome-shaped lens (toric surface) in order to increase the covering area as much as possible and to increase the effective aperture ratio of the pixel, and the center point of the first photoelectric conversion unit and the microlens are used. Are arranged so that their center points coincide with each other. This micro lens 5 is 1A, 2
A pixel is mounted on the entire surface without distinction.

Thus, the aperture on the second photoelectric conversion section can be efficiently illuminated, and the effective aperture ratio of the solid-state imaging device having the function of monitoring the amount of incident light during exposure is increased, and at the same time, the amount of incident light is monitored. Is also possible.

Although the effective aperture ratio of each pixel is slightly lower than that of the first embodiment, since all the microlenses have the same shape and are provided at the same position in the pixel, 1A and 2A
There is no difference in the effective aperture ratio between the pixels, and therefore, there is no need to perform the correction processing. The on-chip micro lens used in the present invention may be a hemispherical lens or a cylindrical lens.

(Embodiment 3) FIG. 5 is a schematic view of a third embodiment of the present invention. This embodiment has the same structure as the first embodiment shown in FIG. 3 except for the microlens. In FIG. 5, 6 is a hole, 7 and 8 are notched microlenses, and 9 is an Al film provided on the side wall of the hole.

In the present embodiment, first, a microlens 3 similar to the microlens 3 of FIG. 3 in the first embodiment is applied to the entire surface, and the separation width is set to 0.2 μm in both the horizontal and vertical directions.
Formed. The micro lens 3 uses a dome-shaped lens (toric surface) in order to increase the covering area as much as possible to increase the effective aperture ratio of the pixel.
Are arranged so that the center point of the photoelectric conversion unit and the center point of the microlens coincide.

Next, by photolithography technology,
A part of the microlens is removed only for the pixel (2A) having the opening 2 on the second photoelectric conversion unit, and a hole 6 is formed in the portion above the opening 2 on the second photoelectric conversion unit. Thereby, the microlenses 7 and 8 that are partially cut are formed.

Further, the side wall of the hole 6 is provided with a light-shielding Al film as shown at 9 in the sectional view of FIG. Processing may be performed so as to prevent light crosstalk with light incident on the opening 1 on the photoelectric conversion unit 1. As a means, after forming a microlens and forming a hole 6, an Al film is deposited on the entire surface by Al sputtering, and only the light-shielding Al film 9 on the side wall of the hole 6 is left by anisotropic etching by RIE. Etching may be performed.

In the embodiments described above, since the microlenses could not be formed in the area B of FIG. 5 for the unit pixel 2A, the light incident on that area could not be focused on the first photoelectric conversion unit. However, in the present embodiment, light incident on the region B can also be collected on the first photoelectric conversion unit, and the effective aperture ratio is improved. Note that the on-chip micro lens used in the present invention may be a hemispherical lens or a cylindrical lens.

(Embodiment 4) FIG. 6 is a schematic view of a fourth embodiment of the present invention. This embodiment has the same structure as the first embodiment shown in FIG. 3 except for the microlens. In the present embodiment, first, a microlens similar to 3 in FIG. 3 in the first embodiment is formed on the entire surface with a separation width of 0.2 μm in both the horizontal and vertical directions. The microlens uses a dome-shaped lens (toric surface) in order to increase the covering area as much as possible and to increase the effective aperture ratio of the pixel, and the center point of the first photoelectric conversion unit and the center of the microlens are used. The points are arranged so that they match.

Next, by photolithography technology,
A part of the microlens is removed from all the pixels, and a hole 6 is opened to open just above the opening 2 of the second photoelectric conversion unit. As a result, the microlens 10 partially having the notch is formed.

As in the sectional view 9 of FIG. 5, a light-shielding Al film is provided on the side wall of the opening (hole) 6 of the microlens, so that light incident on the opening 2 on the second photoelectric conversion unit can be reduced. It is preferable to perform processing for preventing light crosstalk with light incident on the opening 1 on the first photoelectric conversion unit. Thereby, a high effective aperture ratio can be realized as in the third embodiment, and at the same time,
Although the effective aperture ratio of the first photoelectric conversion unit is lower than that of the third embodiment, the difference in the effective aperture ratio between the pixel 1A having no opening on the second photoelectric conversion unit and the pixel 2A is different. There is an advantage that there is no need to perform the correction processing. Note that the on-chip micro lens used in the present invention may be a hemispherical lens or a cylindrical lens.

(Embodiment 5) FIG. 7 is a schematic view of a fifth embodiment of the present invention. In FIG. 7, reference numeral 11 denotes a cylindrical lens. This embodiment has the same structure as the second embodiment shown in FIG. 4 except for the microlens.

The axial direction of the cylindrical lens 11 is horizontal. In the horizontal direction, adjacent microlenses are connected to each other, and one elongated cylindrical microlens 11 is formed in the horizontal direction. Also,
In the vertical direction, the separation width is set large so as to avoid the opening 2 on the second photoelectric conversion unit, and the light is condensed on the first photoelectric conversion unit.

Further, the center line of the cylinder of the microlens is arranged so as to pass through the center point of each first photoelectric conversion unit in the horizontal direction. As a result, the light can be efficiently collected in the aperture 2 on the second photoelectric conversion unit, and the effective aperture ratio of the solid-state imaging device having the function of monitoring the amount of incident light during exposure can be increased, and at the same time, the amount of incident light can be monitored. Becomes Similarly to the second embodiment, the effective aperture ratio of each pixel is slightly lower than that of the first embodiment, but since there is no difference in the effective aperture ratio between the 1A and 2A pixels, it is not necessary to correct the aperture ratio.

Further, as compared with the second embodiment, there is no need to control the horizontal separation width and shape of the microlenses, and there is an advantage that the microlens forming process is simplified.

(Embodiment 6) FIG. 8 is a schematic diagram of a sixth embodiment of the present invention. In FIG. 8, reference numeral 12 denotes a small microlens for condensing light on the first photoelectric conversion unit, and reference numeral 13 denotes a second microlens.
2 shows a microlens that condenses light on a photoelectric conversion unit. The present embodiment is different from the first embodiment shown in FIG.
It has the same structure as.

In this embodiment, a microlens 13 for condensing light on the second photoelectric conversion unit is formed immediately above the opening 2 on the second photoelectric conversion unit. In addition, for the three pixels of the unit pixel 2A and the surrounding unit pixel 1A, a microlens 13 is formed with a microlens 13 and a separation width of 0.2 μm, which condenses light to the first photoelectric conversion unit. The other microlenses 3 for condensing light on the first photoelectric conversion unit are formed with a separation width of 0.2 μm.

The center points of the microlenses 3, 12, and 13 are the first photoelectric conversion unit and the second
Are arranged so as to coincide with the center point of the photoelectric conversion section, and the vertical separation width between the microlenses 12 and the microlenses 3 is large. Therefore, the size of the micro lens 12 is smaller than that of the micro lens 3. In addition, these microlenses use a dome-shaped lens (a lens having a toric surface).

In this embodiment, since the microlenses 13 are also provided on the second photoelectric conversion unit,
The effective aperture ratio of the second photoelectric conversion unit can also be increased. Therefore, even when a small amount of light is exposed, the amount of incident light during exposure can be monitored, and TTL light control with higher sensitivity can be performed.

(Embodiment 7) FIG. 9 is a schematic view of a seventh embodiment of the present invention. In FIG. 9, reference numeral 14 denotes a microlens that condenses light on the first photoelectric conversion unit, and 15 denotes a microlens that condenses light on the second photoelectric conversion unit. This embodiment has the same structure as the second embodiment shown in FIG. 4 except for the microlens. As these microlenses, dome-shaped lenses (lenses having a toric surface) are used.

In the present embodiment, the microlenses 14 of the same shape are provided at the same position in the pixels for all the pixels, and the microlenses 14 are used to cover two openings on the second photoelectric conversion unit. It is provided to avoid. The micro lens 14 is for condensing light on the first photoelectric conversion unit. Further, with respect to the 2A pixel and the pixel on the right side thereof, a microlens 15 for condensing light on the second photoelectric conversion unit is formed, and by increasing the effective aperture ratio of the second photoelectric conversion unit, higher sensitivity is achieved. TTL dimming is possible. Further, since the effective aperture ratios of the first photoelectric conversion units of all the pixels are equal, it is not necessary to perform the aperture ratio correction processing.

The micro lens 1 shown in the present embodiment
4 corresponds to the fifth embodiment (FIG. 7) shown in FIG.
It may be provided on the opening 2 on the second photoelectric conversion unit. Further, the micro lens used in the present invention may be a hemispherical lens or a cylindrical lens.

(Eighth Embodiment) FIG. 10 is a schematic view of an eighth embodiment of the present invention. FIG. 10 is an example relating to a solid-state imaging device including a pixel having three photoelectric conversion units.
For example, in FIG. 15, the pixel having three photoelectric conversion units includes a photodiode 201 as a first photoelectric conversion unit, a main electrode (reset drain) of a reset transistor _{QRSG as} a second photoelectric conversion unit, and a junction-type electric field. A pixel in which the gate region of the effect transistor JFET serves as a third photoelectric conversion portion. In FIG. 2, the pixel has an opening in both the region of the JFET 101 and the portion corresponding to the gate. .

In FIG. 10, reference numeral 2 'denotes an opening provided above the third photoelectric conversion unit such as the gate region of the JFET as described above, and reference numeral 16 denotes a small opening provided on the first photoelectric conversion unit. A microlens 17 is a microlens provided on the second photoelectric conversion unit, and 18 is a microlens provided on the third photoelectric conversion unit. As these microlenses, dome-shaped lenses (lenses having a toric surface) are used.

In this embodiment, the pixel 2A has
Three micro lenses 16, 17, 18 are provided. These microlenses are arranged so that the centers of the first, second, and third photoelectric conversion units coincide with each other, and converge on the corresponding photoelectric conversion units. In the right, upper, and upper right pixels 1A of the pixel 2A, the microlens 16 on the first photoelectric conversion unit has the same shape as that in the pixel 2A, and is smaller than the microlens 3 in the other pixels 1A. Has become. This is to keep a separation distance from the micro lenses 17 and 18.

According to this embodiment, the microlenses 17 and 1 for condensing light on the second and third photoelectric conversion units are provided.
Since 8 is formed, the effective aperture ratio of these photoelectric conversion units can be increased, and TTL dimming with higher sensitivity can be performed. The micro lens used in the present invention may be a hemispherical lens or a cylindrical lens.

(Embodiment 9) FIG. 11 is a schematic view of a ninth embodiment of the present invention. In FIG. 11, reference numeral 19 denotes a microlens provided on the second photoelectric conversion unit. The present embodiment has the same structure as the first embodiment shown in FIG. 3 except for the microlenses. In the present embodiment, only the microlens 19 for condensing light on the second photoelectric conversion unit is formed immediately above the opening 2 on the second photoelectric conversion unit. The micro lens 19 is installed so as to avoid the opening on the first photoelectric conversion unit. Second
The pixels having the photoelectric conversion unit are arranged every few pixels to several tens of pixels and are not adjacent to each other, so that the microlens 19 can secure a sufficient separation width from the adjacent microlens 19.

By providing the micro lens 19,
It is possible to efficiently collect light on the second photoelectric conversion unit. Therefore, the effective aperture ratio of the photoelectric conversion unit for TTL light control can also be set freely, and TTL light control with higher sensitivity can be performed. Although the micro lens 19 used in the example of FIG. 11 is a dome-shaped lens, a hemispherical lens or a cylindrical lens may be used.

(Embodiment 10) FIG. 12 shows a first embodiment of the present invention.
FIG. 1 is a block diagram illustrating a schematic configuration of an imaging device according to an embodiment 0. 12, reference numeral 1200 denotes an MPU (microprocessor unit) for controlling image reading; 1201, a timing generator; 1202, a driver for reading an image output signal; 1203, a solid-state imaging device; 1204, an amplifier for an image output signal; A / D converter, 1206 is an aperture ratio correction processing device for performing aperture ratio correction, 1207 is a signal processing device for correcting signals, 1208 is a memory controller, 1209 is an interface of an image output device, and 1210 is an image output device such as a CRT. Device.

The incident light is converted into an electric signal by the image sensor 1203, amplified by the amplifier 1204, and then converted into a digital signal by the A / D converter 1205. And
The aperture ratio is corrected by an aperture ratio correction processing device 1206 as necessary, and is sent to a signal processing device 1207. Signal processing device 12
The signal processing in 07 is conventionally known, and processing appropriately selected as needed is performed. The signal subjected to the signal processing enters the memory controller 1208, is stored in the image memory, and is transmitted to the image output device 1210 via the interface 1209.

FIG. 13 is a flowchart for explaining the operation of the imaging apparatus shown in FIG. The operation of the imaging device will be described based on FIG. When light enters the imaging device (S1), the MPU 1200 determines whether the microlens on the first photoelectric conversion unit (imaging device) of the pixel receiving the light is a standard microlens (S2). The standard one refers to a microlens used for a pixel 1A that is not close to the pixel 2A, for example, the microlens 3 in FIGS.
For example, like the microlens 4 in FIG. 3 and the microlenses 7 and 8 in FIG. 5, it refers to a small or specially shaped microlens used in the pixel 2A and the pixel 1A adjacent thereto.

If the microlens is standard, the processing proceeds to the conventional signal processing (S3a). If the microlens is nonstandard, the aperture ratio is corrected (S3b), and the processing proceeds to the conventional signal processing. Proceed (S3a). Thereafter, image output is performed (S4). As a method of correcting the aperture ratio, for example, when the effective aperture ratio of the standard microlens is 90% and the effective aperture ratio of the nonstandard microlens is 60%, the image pickup device having the nonstandard microlens is used. Set the output signal to 1.5 (= 9
0/60) Corrected to the output and output. By performing the above-described aperture ratio correction processing, it is possible to output an image without unevenness in sensitivity between pixels.

[0083]

As described above, according to the first aspect of the present invention, the second photoelectric converter is efficiently illuminated without lowering the effective aperture ratio of the first photoelectric converter. It becomes possible.

According to the second aspect of the present invention, although the effective aperture ratio of the first photoelectric conversion unit slightly decreases, there is no difference between the effective aperture ratios of the first photoelectric conversion units of all the pixels. There is no need to perform any processing. In addition, it is possible to efficiently light the second photoelectric conversion unit.

According to the third aspect of the present invention, it is possible to efficiently emit light to the second photoelectric conversion unit without lowering the effective aperture ratio of the first photoelectric conversion unit. further,
The microlens can be formed in a region where the microlens could not be formed, and the effective aperture ratio in that portion can be increased.

In the invention according to claim 4, claim 3
Although the effective aperture ratio of the first photoelectric conversion unit is slightly reduced as compared with the invention according to the first aspect, there is no difference in the effective aperture ratios of the first photoelectric conversion units of all the pixels, and it is necessary to perform the correction processing of the effective aperture ratio. Disappears.

In the invention according to claim 5, it is possible to prevent crosstalk between light incident on the first photoelectric conversion unit and light incident on the second photoelectric conversion unit.

In the invention according to the sixth aspect, an ideal reflection film can be used, and the film is formed by a technique used in a process of manufacturing a solid-state imaging device, such as vapor deposition or anisotropic etching. And the manufacturing method is simplified.

In the invention according to claim 7, it is not necessary to control the separation width and shape in the direction in which the microlenses are connected, and the process of forming the microlenses can be simplified.

In the invention according to the eighth aspect, the effective aperture ratio of the second photoelectric conversion unit is also increased, so that even when imaging is performed with a small amount of light, the amount of light can be monitored and the optimum shutter speed can be set. become able to.

In the ninth aspect, the effective aperture ratio can be increased for each photoelectric conversion unit.

In the invention according to claim 10, the effective aperture ratio of the first photoelectric conversion unit is reduced, but the effective aperture ratio of the second photoelectric conversion unit can be increased, and the second photoelectric conversion unit can be improved. The effective aperture ratio of the portion can be designed relatively freely.

In the invention according to the eleventh aspect, even when the effective aperture ratio of the first element differs between pixels, it is possible to obtain an image output without unevenness in sensitivity among the pixels.

In the twelfth aspect of the present invention, the solid-state image pickup device with the on-chip microlens as the sixth means can be manufactured by the same steps as those for manufacturing the solid-state image pickup device.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a planar structure of a normal unit pixel of an amplification type solid-state imaging device.

FIG. 2 is a schematic diagram showing a planar structure of a unit pixel of an amplification type solid-state imaging device for monitoring an incident light amount in real time during exposure.

FIG. 3 is a schematic diagram showing a first embodiment of the present invention.

FIG. 4 is a schematic diagram showing a second embodiment of the present invention.

FIG. 5 is a schematic diagram showing a third embodiment of the present invention.

FIG. 6 is a schematic diagram showing a fourth embodiment of the present invention.

FIG. 7 is a schematic diagram showing a fifth embodiment of the present invention.

FIG. 8 is a schematic diagram showing a sixth embodiment of the present invention.

FIG. 9 is a schematic diagram showing a seventh embodiment of the present invention.

FIG. 10 is a schematic diagram showing an eighth embodiment of the present invention.

FIG. 11 is a schematic diagram showing a ninth embodiment of the present invention.

FIG. 12 is a schematic diagram showing a tenth embodiment of the present invention.

13 is a diagram for explaining the operation of the imaging device shown in FIG.

FIG. 14 is a diagram showing the structure of a conventional solid-state imaging device with microlenses.

FIG. 15 is a schematic configuration diagram of the invention of the prior application.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Opening on 1st photoelectric conversion part 1A ... Unit pixel without 2nd photoelectric conversion part 2 ... Opening on 2nd photoelectric conversion part 2 '... Opening on 3rd photoelectric conversion part 2A: Unit pixel having a second photoelectric conversion unit 3: Standard on-chip microlens 4: Non-standard on-chip microlens focused on the first photoelectric conversion unit 5: Small standard on-chip microlens 6: Hole 7 Reference numeral 8: On-chip micro lens having a notch 9: Al film 10: Standard on-chip micro lens having a notch 11: Cylindrical lens 12: Small on-chip micro lens 13 for condensing light on the first photoelectric converter 13 ... On-chip microlens for focusing on the second photoelectric converter 14 ... Small standard on-chip microlens 15 ... On-chip microlens for focusing on the second photoelectric converter 6 ... Small on-chip microlens for focusing on the first photoelectric conversion unit 17 ... On-chip microlens for focusing on the second photoelectric conversion unit 18 ... On-chip microlens for focusing on the third photoelectric conversion unit 19 ... On-chip microlens condensing on the second photoelectric conversion unit 100... Photoelectric conversion unit (BPD) 101... JFET 102... Reset drain (RSD) 103... Transfer gate (TG) 104. 106 ... RSD electrode 107 ... JFET source electrode 108 ... RSD opening 1200 ... MPU for image readout control 1201 ... Timing generator 1202 ... Driver for image output signal readout 1203 ... Solid-state image sensor 1204 ... Image output signal amplifier 1205 ... A / D conversion Unit 1206… Aperture ratio correction processor 1207… Signal processor 1208… Memory controller Troller 1209… Image output device interface 1210… Image output device

Claims (12)

[Claims] 1. At least one pixel has first and second photoelectric conversion units, and the first and second photoelectric conversion units include:
An on-chip microlens is provided in a region immediately above the second photoelectric conversion unit for a pixel having a second photoelectric conversion unit, which is a solid-state imaging device that sends signal outputs independent of each other according to the amount of incident light. An on-chip microlens for condensing light on the first photoelectric conversion unit is formed in other areas without being formed, and pixels not having the second photoelectric conversion unit are collected on the first photoelectric conversion unit. A solid-state imaging device with an on-chip micro lens, wherein an on-chip micro lens for emitting light is formed over substantially the entire pixel area of the effective light receiving area. 2. At least one pixel has first and second photoelectric conversion units, and the first and second photoelectric conversion units are:
A solid-state image sensor that sends signal outputs independent of each other in accordance with the amount of incident light. On-chip microlenses in all effective pixels have substantially the same shape so as to converge light on the first photoelectric conversion unit. Is provided in approximately the same place as
Further, each of the on-chip microlenses has a shape such that no on-chip microlens is formed in a region immediately above the second photoelectric conversion unit in a pixel having the second photoelectric conversion unit. Solid-state image sensor with chip micro lens. 3. At least one pixel has first and second photoelectric conversion units, and the first and second photoelectric conversion units include:
An on-chip micro-lens, wherein the on-chip micro-lens is a solid-state imaging device for transmitting independent signal outputs in accordance with the amount of incident light, wherein the on-chip micro-lens is removed only in a region immediately above the second photoelectric conversion unit. With solid-state imaging device. 4. At least one pixel has first and second photoelectric conversion units, and the first and second photoelectric conversion units are:
A solid-state image sensor that sends signal outputs independent of each other in accordance with the amount of incident light. On-chip microlenses in all effective pixels have substantially the same shape so as to converge light on the first photoelectric conversion unit. Is provided in approximately the same place as
The on-chip microlens-mounted solid-state imaging device is characterized in that each on-chip microlens has a shape obtained by removing the on-chip microlens in a region immediately above the second photoelectric conversion unit. 5. The on-chip microlens-equipped solid-state imaging device according to claim 3, wherein a reflection film is formed on a side wall of the hole from which the on-chip microlens has been removed. Solid-state image sensor with chip micro lens. 6. The solid-state imaging device with an on-chip microlens according to claim 5, wherein the reflection film is an Al film. 7. The on-chip microlens-equipped solid-state imaging device according to claim 1, wherein the on-chip microlens for condensing light on the first photoelectric conversion unit is a cylindrical lens. In, the cylindrical lenses of adjacent pixels are connected in the axial direction of the cylinder,
A solid-state imaging device with an on-chip micro lens, which is not separated. 8. The solid-state imaging device with on-chip microlenses according to claim 1, wherein the first photoelectric conversion is provided in a region immediately above the second photoelectric conversion unit. A solid-state imaging device with an on-chip microlens, wherein an on-chip microlens for condensing light on a second photoelectric conversion unit is additionally formed in addition to an on-chip microlens lens formed to condense light on a portion element. 9. A solid-state imaging device having first, second, and third photoelectric conversion units for at least one pixel, wherein each photoelectric conversion unit sends a signal output independent of each other according to the amount of incident light. An on-chip microlens for condensing light on each light receiving surface is formed over substantially the entire pixel region of the effective light receiving region on the light receiving surface of each photoelectric conversion unit. Solid-state image sensor with on-chip micro lens. 10. A solid-state device having first and second photoelectric conversion units for at least one pixel, wherein the first and second photoelectric conversion units transmit signal outputs independent of each other in accordance with the amount of incident light. What is claimed is: 1. An image sensor, comprising: an on-chip micro lens having only an on-chip micro lens for condensing light on a second photoelectric conversion unit. 11. The on-chip microlens-equipped solid-state imaging device according to claim 1,3, 8, or 9, wherein a signal from the first photoelectric conversion unit is converted into an effective aperture ratio. A solid-state imaging device with an on-chip microlens, comprising means for correcting the sensitivity of each pixel on the basis of the above, and adjusting the sensitivity of each pixel. 12. The method for manufacturing a solid-state imaging device with an on-chip microlens according to claim 6, wherein the second photoelectric conversion unit is formed by photolithography after forming the microlens on the upper part of the solid-state imaging device main body. Remove the on-chip microlens in the area immediately above and make a hole,
A method for manufacturing a solid-state imaging device with an on-chip microlens, comprising: depositing an Al film on the entire surface of a hole by sputtering; and thereafter, leaving only the Al film on the side wall of the hole by anisotropic etching by RIE.