JP2007189021A - Solid-state image sensing device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state image sensing device which is capable of preventing its pixel region from varying in photosensitivity according to pixel areas, and to provide its manufacturing method. <P>SOLUTION: The solid-state image sensing device includes two or more photoelectric conversion units 30, charge transfer units 40 provided with charge transfer electrodes which transfer electrical charge produced by the photoelectric conversion units 30, micro-lenses 60 which are formed above the photoelectric conversion units 30 respectively on the surface of a pixel region T, and an intra-layer lens 20 which collects and guides light incident on the micro-lenses 60 to the photoelectric conversion units 30. The intra-layer lens 20 includes lens convexes 21 formed above the photoelectric conversion units 30 respectively, and the lens convexes 21 are formed in such a manner that they grow larger in lens diameter as they are located nearer to the periphery of the pixel region T apart from its center O. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device and a method for manufacturing the solid-state imaging device.

In recent years, in the solid-state imaging device, the demand for higher resolution and higher sensitivity is increasing, and the number of imaging pixels is increasing to more than gigapixels.
An example of the structure of a conventional solid-state image sensor is shown in FIG. As shown in FIG. 5, in the conventional solid-state imaging device 1, a photodiode unit 3 constituting a photoelectric conversion unit is formed on a substrate 2, a planarization layer is formed above the photodiode unit 3, and A structure in which an intralayer lens 4 that also serves as a passivation film is formed on a photodiode portion 3 is known. Further, in the solid-state imaging device 1, a planarizing film, a color filter 7, a planarizing film 8, and an on-chip microlens 6 are sequentially formed on the upper layer lens 4. In the solid-state imaging device 1, the light L incident on the microlens 6 passes through the color filter 7, is condensed on the lens convex portion 5 of the in-layer lens 4, and is received by the photodiode portion 3. This is a structure that is converted into a charge signal in the part 3.

  Incidentally, in the solid-state imaging device 1, the incident angle of incident light is different between the central portion of the image region and the peripheral portion thereof. Then, since the incident angle of the light incident on the microlens 6 is increased with respect to the vertical direction in the peripheral portion of the image region, the light incident from the microlens 6 is the lens convex portion 5 of the in-layer lens 4. Since the amount of light entering the photodiode portion 3 is different, the sensitivity varies between the central portion and the peripheral portion of the image area, resulting in non-uniformity, which is a factor causing deterioration in image quality. It was.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a solid-state imaging device and a method for manufacturing the solid-state imaging device that can prevent variations in light sensitivity depending on the region of the pixel region. There is.

The object of the present invention is to form a photoelectric transfer unit, a charge transfer unit including a charge transfer electrode for transferring charges generated in the photoelectric conversion unit, and a surface of a pixel region on the plurality of photoelectric conversion units. A solid-state imaging device comprising: the microlens and an in-layer lens that collects light incident on the microlens and guides the light to the photoelectric conversion unit,
The in-layer lens has a lens convex portion formed on the photoelectric conversion portion, and the lens convex portion is formed to have a larger lens diameter as the distance from the central portion to the peripheral portion of the pixel region is increased. This is achieved by a solid-state imaging device characterized by

  In addition, the object of the present invention is to form a photoelectric conversion unit, a charge transfer unit including a charge transfer electrode that transfers charges generated in the photoelectric conversion unit, and a surface of a pixel region on the photoelectric conversion unit. A solid-state imaging device comprising: a microlens that is formed; and an in-layer lens that collects light incident on the microlens and guides the light to the photoelectric conversion unit, wherein the photoelectric conversion is performed on the in-layer lens. According to the method for manufacturing a solid-state imaging device, a lens convex portion is formed on an upper portion of the pixel area, and the lens convex portion is formed so as to have a larger lens diameter as the distance from the central portion to the peripheral portion of the pixel region is increased. Achieved.

  In the present invention, the lens convex portion of the in-layer lens is formed so as to have a larger lens diameter as it is closer to the peripheral portion from the central portion of the pixel region of the solid-state imaging device. Then, in the peripheral portion of the pixel region, the light incident on the microlens is more reliably condensed on the lens convex portion of the in-layer lens by increasing the lens diameter. For this reason, even if the incident angle of light in the peripheral part of the pixel region is an angle that is largely inclined with respect to the vertical direction of the surface of the imaging region compared to the incident angle in the central part, the photoelectric conversion unit in the peripheral part of the pixel region It is possible to prevent a difference in light quantity between the light incident on the light and the light incident on the photoelectric conversion unit in the center of the pixel region.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of a solid-state image sensor and the solid-state image sensor which can prevent that a sensitivity variation of light arises with the site | part of a pixel area can be provided.

Embodiments of a lens and a method for manufacturing the lens according to the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view of a solid-state imaging device according to the present invention. FIG. 2 is a plan view of the solid-state imaging device of FIG. FIG. 1 is a cross-sectional view showing the state of the AA line in FIG. 2 in the direction of the arrow.

  As shown in FIG. 1, the solid-state imaging device 10 of the present embodiment has a p-well layer 12 formed on the surface of a silicon substrate 11. A p region 30a and an n region 30b are formed in the p well layer 12, and these form a pn junction. The p region 30a and the n region 30b constitute a photodiode 30 that functions as a photoelectric conversion unit. Signal charges generated in the photodiode 30 are accumulated in the n region 30b.

  On the right side of the photodiode 30, a charge transfer channel 33 composed of an n region is formed at a slight distance. A charge readout region 34 is formed in the p well layer 12 between the n region 30 b and the charge transfer channel 33, and constitutes a charge transfer unit 40.

  The charge transfer unit 40 includes a plurality of charge transfer channels 33 formed side by side in the column direction on the surface of the silicon substrate 11 corresponding to each of the plurality of photodiode columns, and a charge formed in an upper layer of the charge transfer channel 33. It includes a transfer electrode 14 and a charge readout region 34 for reading out the charge generated in the photodiode 30 to the charge transfer channel 33.

  A gate oxide film 13 is formed on the surface of the silicon substrate 11. Although not shown, the gate oxide film 13 is a multilayer structure film (so-called ONO) composed of three layers of a bottom oxide film 13a, a silicon nitride film 13b, and a silicon oxide film 13c formed only under the charge transfer electrode 14. Membrane).

  A charge transfer electrode 14 is formed on the charge readout region 34 and the charge transfer channel 33 with a gate oxide film 13 interposed therebetween. The charge transfer electrode 14 has a single-layer electrode structure composed of a first electrode 14a and a second electrode 14b. An interelectrode insulating film 16 made of a silicon oxide film or the like is formed between the first electrode 14a and the second electrode 14b.

A channel stop 32 made of a p ⁺ region is provided on the right side of the vertical transfer channel 33, and is separated from the adjacent photodiode 30.

  An insulating film 15 made of a silicon oxide film or the like is formed on the charge transfer electrode 13. An antireflection film made of a silicon nitride film or the like is formed on the insulating film 15.

  On the antireflection film, a light shielding film 17 having an opening on the photodiode 30 and made of a tungsten film is formed.

  On the upper side of the light shielding film 17, as an intermediate layer, a planarizing film 72 made of BPSG (borophosphosilicate glass), an insulating film made of P-SiN, and an intralayer lens 20 which also serves as a so-called passivation film, and transparent A lower planarizing film 74 made of resin or the like is formed. Further, the intermediate layer includes a color filter 50 formed on the lower flattening film 74 and an upper flattening film 61 formed on the color filter 50 and made of an insulating transparent resin or the like. Yes. The color filter 50 includes a green filter region, a blue filter region, and a red filter region. The color filter may have a filter separation region (not shown).

  A microlens 60 is provided on the upper surface of the intermediate layer.

  In the solid-state imaging device 10, the signal charge generated in the photodiode 30 is accumulated in the n region 30b, and the signal charge accumulated therein is transferred in the column direction (X direction in FIG. 2) by the charge transfer channel 33 and transferred. The transferred signal charges are transferred in a row direction (Y direction in FIG. 2) by a horizontal charge transfer path (HCCD) (not shown), and a color signal corresponding to the transferred signal charges is output from an amplifier (not shown). ing. That is, the solid-state imaging device 10 has a configuration in which a solid-state imaging device portion that is a pixel region and a peripheral circuit portion that is a region where a peripheral circuit (PAD portion or the like) is formed.

  The intralayer lens 20 has a lens convex portion 21 in which a curved surface protruding upward is formed on the upper portion of each photodiode 30.

  FIG. 3 shows a state in which the entire solid-state imaging device of the present embodiment is viewed in plan. In general, the solid-state imaging device 10 has a peripheral circuit portion formed around it, and a pixel region T formed inside the peripheral circuit portion. In FIG. 3, the center line of the vertical dimension and the center line of the horizontal dimension of the imaging region T are indicated by broken lines, and the position where the center lines intersect with each other is a central portion O of the pixel region T.

  The solid-state imaging device 10 is formed so that the lens convex portion 21 of the in-layer lens 20 has a larger lens diameter as it is closer to the peripheral portion (peripheral portion of the pixel region T) from the central portion O of the pixel region T.

  FIG. 4 is a diagram illustrating the dimensions of the convex portions of the intralayer lenses having different positions in the pixel region. As shown in FIG. 4A, in the intralayer lens 20, a lens convex portion 21a, a lens convex portion 21b, and a lens convex portion 21c are formed in the order closer to the central portion O of the pixel region T. In the in-layer lens 20, the lens convex portion 21b is formed such that the lens diameter D2 is larger than the lens diameter D1 of the lens convex portion 21a formed at a position closest to the central portion O. The convex portion 21c is formed such that the lens diameter D3 is larger than the lens diameters D1 and D2 of the lens convex portion 21a and the lens convex portion 21b at the center portion O, respectively.

  The solid-state imaging device 10 may be configured such that the lens convex portion of the in-layer lens 20 gradually increases from the central portion O toward the outside in the radial direction, and increases stepwise from the central portion O every predetermined distance. It may be configured.

  The solid-state imaging device 10 is formed so that the lens convex portion 21 of the in-layer lens 20 has a larger lens diameter as it is closer to the peripheral portion from the central portion O of the pixel region T of the solid-state imaging device 10. Then, in the peripheral portion of the pixel region T, the light incident on the microlens 60 is more reliably condensed on the lens convex portion 21 of the in-layer lens 20 by increasing the lens diameter. For this reason, even if the incident angle of light in the peripheral part of the pixel region T is an angle that is largely inclined with respect to the vertical direction of the surface of the imaging region as compared to the incident angle in the central part, the photoelectric in the peripheral part of the pixel region T is It is possible to prevent a difference in light amount between the light incident on the conversion unit (photodiode) 30 and the light incident on the photoelectric conversion unit 30 in the central portion of the pixel region T. Therefore, according to the solid-state imaging device 10 of the present invention, it is possible to prevent variation in light sensitivity depending on the region of the pixel region T.

It is sectional drawing of the solid-state image sensor which concerns on this invention. It is a top view of the solid-state image sensor of FIG. The state which planarly viewed the whole solid-state image sensor is shown. It is a figure which shows the dimension of the convex part of the inner lens from which a position differs in a pixel area | region. It is a figure which shows the structure of the conventional solid-state image sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Solid-state image sensor 14 Charge transfer electrode 20 In-layer lens 21 Lens convex part 30 Photoelectric conversion part 40 Charge transfer part 60 Micro lens T Pixel area

Claims (2)

A photoelectric conversion unit;
A charge transfer unit including a charge transfer electrode for transferring charges generated in the photoelectric conversion unit;
On the surface of the pixel region, a microlens formed on the plurality of photoelectric conversion units,
A solid-state imaging device including an in-layer lens that collects light incident on the microlens and guides the light to the photoelectric conversion unit;
The in-layer lens has a lens convex portion formed on the photoelectric conversion portion, and the lens convex portion is formed to have a larger lens diameter as the distance from the central portion to the peripheral portion of the pixel region is increased. A solid-state imaging device. A photoelectric conversion unit;
A charge transfer unit including a charge transfer electrode for transferring charges generated in the photoelectric conversion unit;
On the surface of the pixel region, a microlens formed on the photoelectric conversion unit,
A method of manufacturing a solid-state imaging device including an in-layer lens that collects light incident on the microlens and guides the light to the photoelectric conversion unit;
A lens convex part is formed in the upper part of the photoelectric conversion part in the inner layer lens, and the lens convex part is formed so as to have a larger lens diameter as it is closer to the peripheral part from the central part of the pixel region. A method for manufacturing a solid-state imaging device.

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