JP2007150095A - Imaging device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging device and its manufacturing method capable of materializing low smearing without causing the difficulty in a manufacturing process. <P>SOLUTION: On a substrate 11, an imaging device 10 comprises a photoelectric converter 30, a charge transfer 40 provided with an electric charge transmission electrode 13 for transmitting an electric charge made to generate in the photoelectric converter 30, an antireflection film 17 for covering the electric charge transmission electrode 13, and a light shielding film 16 which covers the charge transfer 40 and constitutes the opening on the photoelectric converter 30. An opening 17a which is a part excluding the upper side of the electric charge transmission electrode 13, and carries out an opening on the photoelectric converter 30, is formed in the antireflection film 17. <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, and particularly relates to miniaturization of a solid-state imaging device by securing a passage of hydrogen gas generated during a sintering process.

  In recent years, in solid-state imaging devices, the number of imaging pixels has increased to more than gigapixels, and the miniaturization of pixel areas is also increasing. Under such circumstances, a high-refractive-index film for reflection prevention is formed on the photoelectric conversion part composed of photodiodes, and the light-receiving area is covered with a tungsten light-shielding film to reduce smear. A structure has been proposed (Patent Document 1).

  The conventional solid-state imaging device has a gate insulating film 2 (consisting of a bottom oxide film 2a, a silicon nitride film 2b, and a silicon oxide film 2c) on the surface of the silicon substrate 1, as shown in FIG. A charge transfer electrode 3 is formed through the insulating film 5 and an antireflection film 7 such as a silicon nitride film is formed over the charge transfer electrode 3 through an insulating film 5. In addition, a light shielding film 6 having an opening 6 a on the photoelectric conversion portion is formed on the antireflection film 7.

JP-A-8-316448

  Incidentally, an oxide film 8 is formed between the antireflection film 7 and the light shielding film 6. Here, an opening 7 a is formed in the antireflection film 7 at a position above the charge transfer electrode 3 in order to allow hydrogen gas generated during the sintering process (unbonded hand termination process) to pass therethrough. In this configuration, it is necessary to secure a gap g between the light-shielding film 6 and the antireflection film 7 by the thickness of the oxide film 8, which is a certain limitation for further miniaturization of the solid-state imaging device. It was. When the gap g between the light shielding film 6 and the antireflection film 7 is increased, smear is deteriorated. On the other hand, when the light-shielding film 6 is formed on the antireflection film 7 without forming the oxide film 8 and the gap g is not formed, the effect of the sintering process is reduced because the passage of hydrogen gas is hindered, and the pixel As the area becomes finer, high processing accuracy is required, and there is room for improvement in that the difficulty of the manufacturing process increases.

  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 manufacturing method of the solid-state imaging device capable of realizing low smear without increasing the difficulty of the manufacturing process.

  An object of the present invention is to provide a photoelectric transfer unit on a substrate, a charge transfer unit including a charge transfer electrode that transfers charges generated in the photoelectric conversion unit, and an antireflection film that covers the charge transfer electrode. And a light-shielding film covering the charge transfer unit and opening on the photoelectric conversion unit, wherein the antireflection film includes a portion other than the charge transfer electrode and the photoelectric conversion This is achieved by a solid-state imaging device characterized in that an opening is formed on the part.

  Another object of the present invention is to provide a photoelectric transfer unit on a substrate, a charge transfer unit including a charge transfer electrode that transfers charges generated in the photoelectric conversion unit, and a reflection that covers the charge transfer electrode. A solid-state imaging device manufacturing method comprising: an anti-reflection film; and a light-shielding film that covers the charge transfer unit and is opened on the photoelectric conversion unit, wherein the anti-reflection film includes a portion excluding the charge transfer electrode. And it is achieved by the manufacturing method of the solid-state image sensor characterized by forming an opening part on the said photoelectric conversion part.

  In the configuration of the solid-state imaging device according to the present invention, the opening of the antireflection film is formed so as to be located at a portion where the light shielding film is opened on the photoelectric conversion unit. Then, even if the oxide film is not formed on the light shielding film and the antireflection film, it is possible to avoid that the hydrogen gas generated during the sintering process is prevented from flowing through the opening, and the effect of the sintering process is suppressed. It will never be done. Thus, by changing the position of the opening, it is possible to reduce the distance between the light shielding film and the antireflection film without forming an oxide film between the light shielding film and the antireflection film. Smearing can be realized. Further, when manufacturing such a solid-state imaging device, patterning is performed by changing the position of the opening, and the other manufacturing processes only have to perform the same procedure as the conventional one, so the difficulty of the manufacturing process is high. Never become.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of a solid-state image sensor and solid-state image sensor which can implement | achieve low smear can be provided, without raising the difficulty of a manufacturing process.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a plan view of a solid-state imaging device according to the present invention. FIG. 2 is a cross-sectional view showing the state of the solid-state imaging device in FIG.
In the solid-state imaging device 10 of the present embodiment, a p-well layer 31 is formed on the surface of the silicon substrate 11 as shown in FIG. A p region 30a and an n region 30b are formed in the p well layer 31, 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. The signal charge generated in the photodiode 30 is 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 31 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 in the column direction of the surface portion of the silicon substrate 1 corresponding to each of the plurality of photodiode columns, and a charge transfer formed in the upper layer of the charge transfer channel 33. It includes an electrode 13 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 12 is formed on the surface of the silicon substrate 11. Although not shown, the gate oxide film 12 is a multilayer structure film (so-called ONO film) composed of three layers of a bottom oxide film, a silicon nitride film, and a silicon oxide film.

  A charge transfer electrode 13 is formed on the charge readout region 34 and the charge transfer channel 33 via the gate oxide film 2. An interelectrode insulating film 14 made of a silicon oxide film or the like is formed between the charge transfer electrodes 13.

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.

  On the charge transfer electrode 13, an insulating film 15 composed of a two-layer film of a silicon oxide film and a plasma silicon nitride film is formed. An antireflection film 17 made of a silicon nitride film or the like is formed on the insulating film 15.

  A light shielding film 16 made of a tungsten film having an opening 16 a on the photodiode 30 is formed on the antireflection film 17.

  On the upper side of the light shielding film 16, as a middle layer, a flattening film 72 made of BPSG (borophosphosilicate glass), an insulating film (so-called passivation film) 73 made of P-SiN, and a lower flattening made of transparent resin or the like. A chemical film 74 is formed. The intermediate layer includes color filters 50G and 50B formed on the upper planarization film 74, and an upper planarization film 61 made of an insulating transparent resin and the like formed on the color filters 50G and 50B. have. The color filter 50G is a green filter layer, the color filter 50B is a blue filter layer, and further, although not shown, a red filter layer is formed. 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, signal charges generated in the photodiode 30 are accumulated in the n region 30b, and the accumulated signal charges are transferred in the column direction by the charge transfer channel 33, and the transferred signal charges are not illustrated. The signal is transferred in the row direction by a horizontal charge transfer path (HCCD), and a color signal corresponding to the transferred signal charge is output from an amplifier (not shown). That is, the solid-state image sensor 10 is formed on a silicon substrate 11 with a solid-state image sensor unit that is a region including a photoelectric conversion unit, a charge transfer unit, an HCCD, and an amplifier, and a peripheral circuit (PAD unit or the like) of the solid-state image sensor. In this configuration, a peripheral circuit portion that is a region to be formed is formed.

  In the solid-state imaging device 10, an opening 17 a is formed in the antireflection film 17 so that at least a part of the opening 16 a of the light shielding film 16 is opened. In the conventional solid-state imaging device, the opening of the antireflection film is formed on the charge transfer electrode. However, in the solid-state imaging device 10 of this embodiment, the opening 17a is formed in a region other than on the charge transfer electrode 13. ing. A light shielding film 16 is formed immediately above the antireflection film 17 covering the charge transfer electrode 13 without forming an oxide film or the like.

  In the opening 16 a of the light shielding film 16, a portion (hereinafter referred to as a hydrogen path) W where the opening 17 a of the antireflection film 17 opens has a function of releasing generated hydrogen when performing a sintering process on the interface of the silicon substrate 11. is doing.

  Next, an embodiment of a method for manufacturing a solid-state imaging device according to the present invention will be described. 3 to 7 are cross-sectional views showing a part of the manufacturing procedure of the solid-state imaging device of the present embodiment. In the embodiments described below, members having the same configuration / action as those already described are denoted by the same or corresponding reference numerals in the drawings, and description thereof is simplified or omitted.

  The solid-state imaging device 10 is different from the conventional solid-state imaging device in that the opening 17a is positioned at the opening 16a of the light shielding film 16 when the antireflection film 17 is formed. Note that the configuration of the silicon substrate 11 of the solid-state image pickup device of the present embodiment, the procedure for forming the intermediate layer, and the microlens 60 are the same manufacturing processes as those of the conventional solid-state image pickup device.

  First, as shown in FIG. 3, the field oxide film 12 is formed on the silicon substrate 11 on which the photodiode 30 is formed. As described above, the field oxide film 12 is a multilayer structure film composed of three layers of a bottom oxide film, a silicon nitride film, and a silicon oxide film.

Subsequently, as shown in FIG. 4, a first amorphous silicon film is formed on the field oxide film 12 by a low pressure CVD method using SiH ₄ added with PH ₃ and N ₂ as a reactive gas. . Thereafter, the first amorphous silicon film is patterned to form a first electrode. Although not shown, a silicon oxide film having a thickness of about 15 nm may be formed by thermally oxidizing the surface of the first electrode. Similarly, a second amorphous silicon film is formed and patterned to form a second electrode. The solid-state imaging device 10 of the present embodiment has a single-layer electrode structure in which a first electrode and a second electrode are arranged in a single layer. These first electrode and second electrode are referred to as a charge transfer electrode 13.

  After the charge transfer electrode 13 is formed, an insulating film 15 composed of a two-layer film of a silicon oxide film and a plasma silicon nitride film is formed on the charge transfer electrode 13.

  After forming the insulating film 15, as shown in FIG. 5, an antireflection film 17 having a film thickness of about 30 nm made of a silicon nitride film which is a high refractive index material is formed on the entire surface of the insulating film 15 by CVD or ion doping. To do.

  Next, as shown in FIG. 6, an opening 17a is formed in the antireflection film 17 by a photolithography process. At this time, exposure and development are performed using a mask having a predetermined pattern so that the opening 17a is located on the photodiode 30 (photoelectric conversion unit) except for the portion on the charge transfer electrode 13.

  After the antireflection film 17 is formed, a light shielding film 16 made of a tungsten thin film is formed so as to cover the charge transfer portion 40. The light shielding film 16 is formed in a region except on the photodiode 30, and an opening 16 a is provided on the photodiode 30.

  The size of the opening 17 a of the antireflection film 17 is not particularly limited, but at least a part of the opening 17 a is configured to open at the opening 16 a of the light shielding film 16. This opened portion functions as a hydrogen path when the silicon substrate 11 is sintered.

  According to this embodiment, the solid-state imaging device 10 is formed at a position where the opening 17a of the antireflection film 17 is opened at the opening 16a of the light shielding film 16 on the photodiode 30 (photoelectric conversion unit). As a result, even if an oxide film is not formed between the light shielding film 16 and the antireflection film 17, the hydrogen gas generated when the silicon substrate 11 is subjected to the sintering process may be prevented from flowing through the opening 17a. This can be avoided and the effect of the sintering process is not suppressed. Thus, by changing the position where the opening 17a of the antireflection film 17 is formed, an oxide film is not formed between the light shielding film 16 and the antireflection film 17, so that the light shielding film 16 and the antireflection film 17 It is possible to reduce the distance between the two, and it is possible to achieve a low smear. Moreover, when manufacturing such a solid-state image sensor 10, the position of the opening 17a may be changed and patterning may be performed, and other manufacturing processes may be performed in the same manner as in the conventional method. Will not be high.

It is a top view which shows the structure of the solid-state image sensor which concerns on this invention. It is sectional drawing which shows the state which looked at the arrow direction of the AA line of the solid-state image sensor of FIG. It is sectional drawing which shows a part of manufacturing procedure of the solid-state image sensor concerning this invention. It is sectional drawing which shows a part of manufacturing procedure of the solid-state image sensor concerning this invention. It is sectional drawing which shows a part of manufacturing procedure of the solid-state image sensor concerning this invention. It is sectional drawing which shows a part of manufacturing procedure of the solid-state image sensor concerning this invention. It is sectional drawing which shows a part of manufacturing procedure of the solid-state image sensor concerning this invention. It is sectional drawing which shows the structure of the conventional solid-state image sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Solid-state image sensor 11 Silicon substrate 13 Charge transfer electrode 16 Light shielding film 17 Antireflection film 17a (Antireflection film) opening 30 Photoelectric conversion part (photodiode)

Claims (2)

On the substrate, a photoelectric conversion unit,
A charge transfer unit including a charge transfer electrode for transferring charges generated in the photoelectric conversion unit;
An antireflection film covering the charge transfer electrode;
A solid-state imaging device including a light-shielding film that covers the charge transfer unit and is opened on the photoelectric conversion unit;
The solid-state image pickup device, wherein the antireflection film is formed with an opening that is open on the photoelectric conversion portion and at a portion other than the charge transfer electrode. On the substrate, a photoelectric conversion unit,
A charge transfer unit including a charge transfer electrode for transferring charges generated in the photoelectric conversion unit;
An antireflection film covering the charge transfer electrode;
A method of manufacturing a solid-state imaging device that includes a light-shielding film that covers the charge transfer unit and is opened on the photoelectric conversion unit,
A method of manufacturing a solid-state imaging device, wherein an opening is formed on a portion of the antireflection film except on the charge transfer electrode and on the photoelectric conversion portion.

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