JP2006032583A - Solid-state imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an amplification CMOS photoelectric transducing device, wherein a proposal is made such that this structure suppresses a peripheral extinction without altering an opening area at the center and periphery. <P>SOLUTION: A solid-state imaging device has: a photoelectric transduing device in which light receiving elements are two-dimensionally and rectangularly arranged on a semiconductor substrate; a storage for storing a signal generated by the light receiving elements; a switching means for controlling an electric charge transfer from the photoelectric transfer to the storage; an amplifier which inputs the potential of the storage, and a means for resetting the input terminal of this amplifier. In the device, a color filter is arranged through a levelling film formed on the entire face, and an ON-chip lens is formed above the color filter. If a maximum entrance light angle to be fetched in the short direction of the rectangular of the photoelectric transfer in the light receiving elements is set at θ1, and a maximum entrance light angle to be fetched in a longitudinal direction thereof is set at θ2, this structure is made such that the angle of an incident light to be fetched to the light receiving elements is set at θ1<θ2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a solid-state imaging device, and particularly to an aperture shape of an amplification CMOS photoelectric conversion device.

  Conventionally, there have been many examples of using a CCD photoelectric conversion element as a solid-state imaging device, but recently there has been a movement to commercialize a CMOS photoelectric conversion element. The CMOS type photoelectric conversion device has been said to be inferior in image quality compared with the CCD type. However, the noise is reduced, the power consumption is lower than that of the CCD type, and it is operated with a single power source. Can be manufactured by the same CMOS process and is easy to integrate.

  Since the CMOS type photoelectric conversion device has a large number of elements per pixel, the aperture ratio can be increased by wiring the metal layers in multiple layers, and an on-chip microlens can be formed to increase the light condensing rate per pixel. This realizes a highly sensitive solid-state imaging device.

  However, the multi-layer wiring of the metal layer increases the distance from the on-chip microlens to the light receiving surface, making it difficult for light having a large incident angle to enter the light receiving surface. Therefore, when the F value of the imaging lens is reduced (the aperture is opened), the incident angle of the chief ray is larger at the end of the chip than at the center of the chip, and the amount of light at the end of the chip is reduced. Dimming occurs.

  FIG. 12 is a cross-sectional view showing the state of peripheral light reduction when the F value of the imaging lens is reduced. 1201 is a principal ray, 1202 is an on-chip microlens, 1203 is a metal wiring layer, and 1304 is a light receiving portion. As can be seen from FIG. 12, the incident angle of the principal ray 1201 is different between the chip center and the chip end, and the chip end is incident on the on-chip microlens 1202 with an angle. Therefore, a part of the light collected by the light receiving unit 1204 is kicked by the metal wiring layer 1203 at the chip end portion, as in 1205, and is not sufficiently condensed on the light receiving unit 1204 at the chip end portion. At this time, the output signal obtained from the solid-state imaging device is as shown in FIG. 13, and the output signal becomes small at the end of the chip, causing shading. This is a very big problem for the performance of sensors such as digital cameras.

  In order to solve such a problem, Patent Document 1 discloses a method of improving the shading as shown in FIG. 13 by increasing the opening area of the peripheral portion (FIG. 14) to increase the sensitivity of the peripheral portion. Proposed.

JP-A-7-143411

  In recent years, the number of pixels in digital camera sensors has increased, and the size of one pixel tends to be reduced. Therefore, in order to realize a highly sensitive sensor, the maximum aperture size is secured in the central pixel portion. There is a need.

  However, since it is impossible to further increase the opening area at the end of the chip while keeping the opening area at the center of the chip at the maximum, Patent Document 1 (Japanese Patent Laid-Open No. 7-143411) is disclosed as means for improving peripheral light reduction. ) Cannot be used.

  In view of this, the present invention proposes a structure that suppresses peripheral dimming in an amplification CMOS photoelectric conversion device without changing the opening area between the central portion and the peripheral portion.

  In order to achieve the above object, the present invention provides a photoelectric conversion unit in which light receiving elements are two-dimensionally and rectangularly arranged on a semiconductor substrate, a storage unit for storing signals generated by the light receiving elements, and the photoelectric conversion unit. A planarizing film formed on the entire surface, having a switching means for controlling charge transfer from the storage section to the storage section, an amplification section for receiving the potential of the storage section, and a means for resetting the input terminal of the amplification section In the solid-state imaging device in which the color filter is disposed via the color filter and the on-chip lens is formed above the color filter, the maximum incident light angle that can be captured in the rectangular short direction of the photoelectric conversion unit in the light receiving element is θ1. This is a solid-state imaging device having a structure in which the angle of incident light that can be captured by the light receiving element is θ1 <θ2, where θ2 is the maximum incident light angle that can be captured in the longitudinal direction. It is possible to suppress the eclipse of the incident light in the metal layer at the end, it is to propose a structure that can suppress the vignette.

  According to the present invention, it is a solid-state imaging device having a structure in which the angle of incident light that can be taken into one light-receiving unit is θ1 <θ2, and by using such a method, incidence on the metal layer at the chip end is performed. It is possible to obtain a structure that can suppress kicking of light and can suppress peripheral dimming. If this is utilized, a camera with a small lens system can be realized.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1>
FIG. 1 shows a first embodiment of the present invention.

  FIG. 1A is a schematic view of the entire light receiving area of the sensor as viewed from above. Reference numeral 101 denotes a light receiving area, and 102 denotes one light receiving portion at the right corner. FIG. 1B is an enlarged view of the light receiving unit 102 at the right corner of FIG. Reference numeral 103 denotes an uppermost metal light shielding layer, and reference numeral 104 denotes an on-chip microlens.

  FIG. 2A shows a cross-sectional view of the right corner light receiving portion 102 of FIG. 1A cut along the short direction A-A ′ of the chip. 103 is the uppermost metal light shielding layer as in FIG. 1B, and 104 is an on-chip microlens. Reference numeral 201 denotes a light receiving unit. θ1 represents the maximum incident light angle of the light incident on the light receiving unit 201. FIG. 2B shows a cross-sectional view of the right corner light receiving portion 102 of FIG. 1A taken along the chip longitudinal direction B-B '.

  103 is the uppermost metal light shielding layer as in FIG. 1B, and 104 is an on-chip microlens. Reference numeral 201 denotes a light receiving unit. θ2 represents the maximum incident light angle of the light incident on the light receiving unit 201.

  In FIG. 3, reference numeral 301 denotes a principal ray, 302 denotes an on-chip microlens, 303 denotes a metal light shielding layer, and 304 denotes a light receiving unit. Normally, the angle of the chief ray of incident light increases as the distance from the center increases, as shown in FIG. For this reason, in the light receiving unit 102 at the right corner shown in FIG. 1A, it can be seen that light having a larger angle is incident on the side in the chip longitudinal direction than on the side in the chip short direction. As a result, the amount of light incident on the light receiving portion at the end of the chip is kicked by the uppermost light-shielding layer and is one of the causes of peripheral dimming.

  In the present embodiment, the opening width x in the longitudinal direction of the light receiving region 101 is larger than the opening width y in the lateral direction. For this reason, in the light receiving portion 102 at the end of the light receiving region, the angle θ2 of the maximum incident light that can be captured in the longitudinal direction is larger than the angle θ1 of the maximum incident light that can be captured in the short direction. As a result, the maximum incident light angle that can be captured is increased in the longitudinal direction where light with a larger angle is incident, so that the kick of incident light at the uppermost metal layer at the end of the chip can be suppressed, Peripheral dimming can be suppressed. FIG. 4 shows an output signal obtained from the sensor in this embodiment. It can be seen that the shading at the tip end is improved.

<Embodiment 2>
FIG. 5 shows a second embodiment of the present invention.

  FIG. 5A is a schematic view of the entire light receiving area of the sensor as viewed from above.

  Reference numeral 501 denotes a light receiving area, and 502 denotes one light receiving portion at the right corner. FIG. 5B is an enlarged view of the light receiving unit 502 at the right corner of FIG. Reference numeral 503 denotes a first metal layer, 504 denotes a second metal layer, and 505 denotes an on-chip microlens. In the light receiving portion of the present embodiment, the opening is determined by the first metal layer 503 in the longitudinal direction, and the second metal layer 504 is determined in the short direction.

  FIG. 6A shows a cross-sectional view of the right corner light receiving portion 502 of FIG. 5A when cut in the short direction A-A ′ of the chip.

  Reference numeral 503 denotes a first metal layer, reference numeral 504 denotes a second metal layer, and reference numeral 505 denotes an on-chip microlens as in FIG. Reference numeral 601 denotes a light receiving unit. θ1 represents the maximum incident light angle of light incident on the light receiving unit 601.

  FIG. 6B shows a cross-sectional view of the right corner light receiving portion 602 of FIG. 5A taken along the chip longitudinal direction B-B ′.

  Reference numeral 503 denotes a first metal layer, reference numeral 504 denotes a second metal layer, and reference numeral 505 denotes an on-chip microlens as in FIG. Reference numeral 601 denotes a light receiving unit. θ2 represents the maximum incident light angle of light incident on the light receiving unit 601.

  In the present embodiment, the opening in the longitudinal direction of the light receiving region 501 is determined by the first metal layer, and the opening in the short direction is determined by the second metal layer. Regardless of whether the opening of the light receiving portion has the same length in both the x-direction and the y-direction, the maximum incident light-shielding angle θ1 that can be taken in the short direction in the light-receiving portion 502 at the end of the light-receiving region due to the difference in height of the light-shielding metal layer. Accordingly, the angle θ2 of the maximum incident light that can be taken in the longitudinal direction is larger. As a result, the maximum incident light angle that can be captured is increased in the longitudinal direction where light with a larger angle is incident, so that the kick of incident light at the uppermost metal layer at the end of the chip can be suppressed, Peripheral dimming can be suppressed. FIG. 7 shows an output signal obtained from the sensor in this embodiment. It can be seen that the shading at the tip end is improved.

<Embodiment 3>
FIG. 8 shows a third embodiment of the present invention.

  FIG. 8A is a schematic view of the entire light receiving area of the sensor as viewed from above. Reference numeral 801 denotes a light receiving region, and 802 denotes one light receiving portion at the right corner. FIG. 8B is an enlarged view of the light receiving unit 802 at the right corner of FIG. Reference numeral 803 denotes an uppermost metal light shielding layer, and reference numeral 804 denotes an on-chip microlens. Reference numeral 805 denotes a gate electrode layer of a switch that controls charge transfer.

  FIG. 9A shows a cross-sectional view of the right corner light receiving portion 802 of FIG. 8A when cut along the short direction A-A ′ of the chip. Reference numeral 803 denotes the uppermost metal light shielding layer as in FIG. 1B, and reference numeral 804 denotes an on-chip microlens. Reference numeral 805 denotes a gate electrode layer of a switch that controls charge transfer. Reference numeral 901 denotes a light receiving unit. θ1 represents the maximum incident light angle of light incident on the light receiving unit 901. FIG. 9B shows a cross-sectional view of the right corner light receiving portion 802 of FIG. 8A taken along the longitudinal direction B-B ′ of the chip. Reference numeral 803 denotes the uppermost metal light shielding layer as in FIG. 1B, and reference numeral 804 denotes an on-chip microlens. Reference numeral 805 denotes a gate electrode layer of a switch that controls charge transfer. Reference numeral 201 denotes a light receiving unit. θ2 represents the maximum incident light angle of the light incident on the light receiving unit 201.

  In this embodiment mode, a gate electrode layer 805 of a switch that controls charge transfer is arranged in parallel to the longitudinal direction of the light receiving region 801. As described above, light having a larger angle is incident on the side in the longitudinal direction of the chip than on the side in the lateral direction of the chip. However, as can be seen from FIG. The gate electrode layer of the transfer switch is not arranged in the side direction. For this reason, light can be taken in without obstructing the gate electrode layer even in the longitudinal side where the peripheral light attenuation is severe. FIG. 10 shows an output signal obtained from the sensor in this embodiment. It can be seen that the shading at the tip end is improved.

<Embodiment 4>
FIG. 11 shows a fourth embodiment of the present invention.

  FIG. 11A is a schematic view of the entire light receiving area of the sensor as viewed from above. Reference numeral 1101 denotes a light receiving area, and 1102 denotes one light receiving portion at the right corner. FIG. 11B is an enlarged view of the light receiving unit 1102 at the right corner of FIG. Reference numeral 1103 denotes a first metal layer, 1104 denotes a second metal layer, and 1105 denotes an on-chip microlens. Reference numeral 1106 denotes a gate electrode layer of a switch for controlling charge transfer. A gate electrode of the transfer switch is arranged in parallel with the first metal layer 1103 that defines the opening in the longitudinal direction. For this reason, the same effect as in the third embodiment can be obtained, and light can be taken in without being disturbed by the gate electrode layer even in the longitudinal direction where the peripheral dimming is severe.

It is the figure which showed the solid-state imaging device which concerns on Embodiment 1 of this invention. It is the figure which showed the cross section of the solid-state imaging device which concerns on Embodiment 1 of this invention. It is the figure which showed the concept of the solid-state imaging device which concerns on Embodiment 1 of this invention. It is the figure which showed the improvement result of the solid-state imaging device which concerns on Embodiment 1 of this invention. It is the figure which showed the solid-state imaging device which concerns on Embodiment 2 of this invention. It is the figure which showed the cross section of the solid-state imaging device which concerns on Embodiment 2 of this invention. It is the figure which showed the improvement result of the solid-state imaging device concerning Embodiment 2 of this invention. It is the figure which showed the solid-state imaging device which concerns on Embodiment 3 of this invention. It is the figure which showed the cross section of the solid-state imaging device which concerns on Embodiment 3 of this invention. It is the figure which showed the improvement result of the solid-state imaging device which concerns on Embodiment 3 of this invention. It is the figure which showed the solid-state imaging device which concerns on Embodiment 4 of this invention. It is a figure explaining the phenomenon of peripheral light reduction. It is a figure explaining the phenomenon of peripheral light reduction. It is the figure which showed the prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Light reception area 102 Light reception part 103 Metal light shielding layer 104 On-chip microlens 201 Light reception part 301 Main light source 302 On-chip microlens 303 Metal light shielding layer 304 Light reception part 501 Light reception area 502 Light reception part 503 1st metal layer 504 2nd metal Layer 505 On-chip microlens 601 Light receiving portion 801 Light receiving region 802 Light receiving portion 803 Metal light shielding layer 804 On-chip microlens 805 Gate electrode layer 901 Light receiving portion 1101 Light receiving region 1102 Light receiving portion 1103 First metal layer 1104 Second metal layer 1105 On-chip microlens 1106 Gate electrode layer

Claims (5)

A photoelectric conversion unit in which light receiving elements are two-dimensionally and rectangularly arranged on a semiconductor substrate, a storage unit for storing signals generated by the light receiving elements, and charge transfer from the photoelectric conversion unit to the storage unit are controlled. A switching unit, an amplification unit that receives the potential of the storage unit, and a unit that resets an input terminal of the amplification unit, and a color filter is disposed through a planarization film formed on the entire surface, In the solid-state imaging device in which the on-chip lens is formed above the color filter,
Assuming that the maximum incident light angle that can be captured in the rectangular lateral direction of the photoelectric conversion unit in the light receiving element is θ1, and the maximum incident light angle that can be captured in the longitudinal direction is θ2, the angle of incident light that can be captured in the light receiving element is θ1 <θ2. A solid-state imaging device having the structure as described above. A photoelectric conversion unit in which light receiving elements are two-dimensionally and rectangularly arranged on a semiconductor substrate, a storage unit for storing signals generated by the light receiving elements, and charge transfer from the photoelectric conversion unit to the storage unit are controlled. A switching unit, an amplification unit that receives the potential of the storage unit, and a unit that resets an input terminal of the amplification unit, and a color filter is disposed through a planarization film formed on the entire surface, In the solid-state imaging device in which the on-chip lens is formed above the color filter,
A solid-state imaging device, wherein an opening shape of the light receiving element is determined by an uppermost metal wiring, and the opening shape is a rectangle having the same short-side direction and a long-side direction as the rectangle of the photoelectric conversion unit. A photoelectric conversion unit in which light receiving elements are two-dimensionally and rectangularly arranged on a semiconductor substrate, a storage unit for storing signals generated by the light receiving elements, and charge transfer from the photoelectric conversion unit to the storage unit are controlled. A switching unit, an amplification unit that receives the potential of the storage unit, and a unit that resets an input terminal of the amplification unit, and a color filter is disposed through a planarization film formed on the entire surface, In the solid-state imaging device in which an on-chip lens is formed above the color filter, one side determining the opening shape of the light receiving element is determined by the first metal wiring layer, and the other side is defined by the second metal wiring layer.
A solid-state imaging device, wherein a rectangular longitudinal opening of the photoelectric conversion portion is defined by a first metal wiring layer, and a short-side opening is defined by a second metal wiring layer.   3. The solid-state imaging device according to claim 2, wherein a gate electrode layer of the switch for controlling the charge transfer is arranged in parallel with the longitudinal direction of the opening shape.   4. The solid-state imaging device according to claim 3, wherein a gate electrode layer of the switch for controlling the charge transfer is arranged in parallel with the first metal wiring layer.

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