JP2007005493A - Solid-state imaging device, its manufacturing method, and electronic information apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent oblique incident light which is a cause of a smear, and to prevent damages to a semiconductor substrate to a minimum. <P>SOLUTION: A solid-state imaging device 20 has on a surface of a Si substrate 1 a plurality of photodiodes 3 for transferring incident light photoelectrically, a transfer gate 4 for reading out signal charges from these photodiodes 3, and a CCD 5 serving as a charge transfer for transferring the signal charges read out through the transfer gate 4 to a given direction. Gate electrodes 9A are provided on the transfer gate 4, and the CCD 5 through gate insulating films 8a, 8b. A trench 7A is formed in the Si substrate 1, and the photodiode 3, the transfer gate 4, the CCD 5 and the gate electrode 9A are formed on the surface of the Si substrate 1 with the trench 7A. Thereafter, a shade film 11A is embedded in the trench 7A so as to cover the CCD 5 crosswise. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device capable of imaging a subject and a manufacturing method thereof, and an electronic information device such as a digital still camera, a digital movie camera, and a camera-equipped mobile phone device using the solid-state imaging device as an imaging unit.

  This type of conventional solid-state imaging device has a plurality of photodiode portions (light receiving portions) that photoelectrically convert incident light on the surface of a semiconductor substrate, a transfer gate portion that reads signal charges from the photodiode portions, and the transfer gate. A charge transfer unit (CCD unit) for transferring the signal charges read by the unit in a predetermined direction, and a gate electrode is provided on the transfer gate unit and the CCD unit via a gate insulating film. . In this solid-state imaging device, incident light from a subject is photoelectrically converted by each photodiode unit, and the signal charges subjected to photoelectric conversion are sequentially transferred to and detected by a charge detection unit via a transfer gate unit and a CCD unit. .

  Here, when light is incident on a part other than the photodiode part, for example, a transfer gate part or a CCD part, the signal charge detection is affected. Therefore, only the photodiode part is opened, and the transfer part other than the photodiode part is opened. A light shielding film is provided so as to cover the gate portion, the CCD portion, and the like.

  For example, Patent Document 1 discloses a solid-state imaging device in which a groove portion is provided in a Si substrate, a gate electrode made of polysilicon is embedded in the groove portion, and a light shielding film is provided thereon.

  Below, the conventional solid-state image sensor currently disclosed by this patent document 1 is demonstrated with reference to FIGS.

  FIG. 10 is a longitudinal cross-sectional view showing an example of a main unit configuration of a conventional solid-state imaging device.

  In FIG. 10, a conventional solid-state imaging device 100 includes a plurality of photodiode portions 3 that photoelectrically convert incident light into a well region 2 provided on the surface of the Si substrate 1, and the photodiode portions 3. A transfer gate unit 4 that reads signal charges, a CCD unit 5 that is a charge transfer unit that transfers signal charges read by the transfer gate unit 4 in a predetermined direction, and the photodiode unit 3 of the pixel unit are adjacent to each other. A channel stop unit 6 that separates the pixel unit from the CCD unit 5 is provided.

  These transfer gate unit 4, CCD unit 5, and channel stop unit 6 are provided in the groove 7 of the Si substrate 1, and gates are provided on these transfer gate unit 4 and CCD unit 5 via a gate insulating film 8. An electrode 9 is provided. An interlayer insulating film 10 is provided on the gate electrode 9, and a light-shielding film 11 having a predetermined pattern having an opening B on the photodiode portion 3 is provided thereon. The light shielding film 11 covers the gate electrode 9 and the interlayer insulating film 10 and fills the groove 7.

  With the above configuration, a method for manufacturing the conventional solid-state imaging device 100 will be described below with reference to FIGS. 11 (a) to 11 (c) and FIGS. 12 (a) to 12 (c).

  First, as shown in FIG. 11A, a groove 7 is formed in a silicon (Si) substrate 1 provided with a well region 2. The groove 7 can be formed by etching or a method of removing the oxide film after oxidizing the Si substrate 1. Here, the groove 7 is formed by performing an etching process using a resist film 7a having a predetermined pattern opened on the substrate portion to be the groove 7 as a mask.

  Next, as shown in FIG. 11B, an oxide film (gate insulating film 8) is formed so as to cover the surface of the well region 2, and the oxide film (gate insulating film 8) is interposed therebetween. Ions are implanted into the well region 2 to form the photodiode portion 3, the transfer gate portion 4, the CCD portion 5 and the channel stop portion 6 arranged in the horizontal direction as shown in FIG. . At this time, the transfer gate unit 4, the CCD unit 5, and the channel stop unit 6 are formed in the groove 7.

  Further, as shown in FIG. 12A, a gate electrode 9 made of polysilicon or the like is formed over the transfer gate portion 4 and the CCD portion 5 through an oxide film used as the gate insulating film 8. At this time, the gate electrode 9 is processed so that a gap is formed between the end of the groove 7 and the gate electrode 9.

  Subsequently, as shown in FIG. 12B, an interlayer insulating film 10 is formed so as to cover the gate electrode 9. At this time, the interlayer insulating film 10 is formed so that a gap is formed between the end of the trench 7 and the interlayer insulating film 10 as in the case of the gate electrode 9.

Thereafter, as shown in FIG. 12C, a light shielding film material to be the light shielding film 11 is formed on the wafer surface. At this time, the light shielding film material to be the light shielding film 11 is buried in the gap between the end of the groove 7 and the interlayer insulating film 10. The opening B is formed by selectively removing the light shielding film material on the photodiode portion 3 by etching. In this way, the light shielding film 11 is processed into a predetermined pattern. Accordingly, light can be incident only on the photodiode portion 2 through the opening B of the light shielding film 11 on the photodiode portion 2.
Japanese Patent Laid-Open No. 2004-319959

  However, in the conventional solid-state imaging device 100, light obliquely incident from the opening B of the light shielding film 11 (hereinafter referred to as oblique incident light) is not only in the photodiode portion 3 but also under the channel stop portion 6. There is a case where the electric charge is improperly generated in the CCD unit 5 of the adjacent pixel unit. This is called smear, and this smear depends on the opening B of the light shielding film 11.

  In the conventional solid-state imaging device 100 disclosed in Patent Document 1, by embedding the gate electrode 9 and the light-shielding film 11, an effect of mitigating oblique incident light can be obtained, but it is incident on the lower side of the channel stop unit 6. It was insufficient to prevent smear due to light.

  Further, since the groove 7 must be formed in the Si substrate 1 in a wide range in order to embed the gate electrode 9 and the light shielding film 11, the burden on the Si substrate 1 is large, which may cause crystal defects and the like. The nature is great. Due to this crystal defect or the like, there is a large possibility that white defect, which is a defect peculiar to CCD, increases.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and prevents a solid incident image element that can cause smear and can prevent damage to a semiconductor substrate to a minimum. For example, an electronic information device such as a digital still camera, a digital movie camera, and a camera-equipped mobile phone device is used.

  In the solid-state imaging device of the present invention, a photodiode portion for each pixel portion that photoelectrically converts incident light and a charge transfer portion that can transfer signal charges read from the photodiode portion are provided on a semiconductor substrate. In the solid-state imaging device, a groove having a predetermined depth from the surface of the semiconductor substrate is provided between the pixel portion between the photodiode portion of the pixel portion and the charge transfer portion of the pixel portion adjacent to the pixel portion. A light shielding film is provided so as to bury the groove for light shielding, open above the photodiode portion, and cover at least the charge transfer portion, thereby achieving the above object.

  Preferably, the predetermined depth of the groove in the solid-state imaging device of the present invention is formed to be equal to or deeper than the depth of the charge transfer portion.

  Furthermore, preferably, the light shielding film in which the groove in the solid-state imaging device of the present invention is embedded covers the charge transfer portion from the side of the photodiode portion.

  Still preferably, in a solid-state imaging device according to the present invention, the light shielding film embeds the groove so as to block oblique incident light from the opening above the photodiode portion.

  Further preferably, in the solid-state imaging device of the present invention, the surface of the charge transfer portion and the surface of the photodiode portion are configured to be flush with each other.

  Further preferably, the width of the groove in the solid-state imaging device of the present invention is such that the film thickness dimension of the light shielding film necessary for light shielding and the film thickness dimension of the light shielding film are twice the film thickness of the predetermined interlayer insulating film. One of the added film thickness dimensions.

  Further, preferably, in the solid-state imaging device of the present invention, a channel stop portion for separating between the photodiode portion of the pixel portion and the charge transfer portion of the pixel portion adjacent to the pixel portion has a predetermined depth from the bottom portion of the groove. Is provided.

  Further preferably, the predetermined depth of the channel stop portion in the solid-state imaging device of the present invention is formed to be equal to or deeper than the depth of the charge transfer portion.

  Further preferably, in the solid-state imaging device according to the present invention, a transfer gate portion is provided between the photodiode portion and the charge transfer portion so that a signal charge can be read from the photodiode portion to the charge transfer portion. A gate electrode is provided on the transfer gate portion and the charge transfer portion via a gate insulating film.

  Further preferably, in the solid-state imaging device of the present invention, the photodiode portion and the groove are provided between adjacent gate electrodes.

  The solid-state imaging device manufacturing method of the present invention includes a groove and channel stop portion forming step of forming a groove of a predetermined depth between regions to be each pixel portion of a semiconductor substrate and forming a channel stop portion at the bottom of the groove , A photodiode unit for each pixel unit that photoelectrically converts incident light, a transfer gate unit that can read signal charges from the photodiode unit, and a signal charge read through the transfer gate unit can be transferred An element portion forming step for forming a charge transfer portion, a gate electrode forming step for forming a gate electrode on the transfer gate portion and the charge transfer portion via a gate insulating film, and on the gate electrode and in the groove A light-shielding film forming step of forming a light-shielding film so as to be embedded and opening the light-shielding film on the photodiode portion. The purpose is achieved.

  Preferably, the groove and channel stop forming step in the method for manufacturing a solid-state imaging device of the present invention includes forming the groove to a predetermined depth by etching using a mask having a predetermined pattern, and using the mask to The channel stop portion is formed by ion implantation at the bottom of the groove.

  Further preferably, in the etching process for forming a groove in the method for manufacturing a solid-state imaging device of the present invention, the semiconductor substrate is selectively removed by dry etching.

  Further preferably, when an oxide film is formed on the surface of the semiconductor substrate in the method for manufacturing a solid-state imaging device of the present invention, the etching condition is determined using fluorine-based gas and the oxide film material. The selection ratio with respect to the material of the semiconductor substrate is set to 1 or more.

  Furthermore, it is preferable that the predetermined depth of the groove in the method for manufacturing a solid-state imaging device of the present invention is equal to or greater than the depth position of the charge transfer portion.

  Further preferably, the predetermined depth of the channel stop portion in the method for manufacturing a solid-state imaging device of the present invention is formed to be equal to or deeper than the depth of the charge transfer portion.

  Further preferably, the element portion forming step in the method for manufacturing a solid-state imaging device of the present invention includes a transfer gate portion forming step of forming the transfer gate portion by ion implantation using a mask having a predetermined pattern, and one of adjacent grooves. A charge transfer portion forming step of forming the charge transfer portion between the transfer gate portion by ion implantation using a mask of a predetermined pattern, and the photodiode portion between the other of the adjacent grooves and the transfer gate portion. The photodiode part forming step formed by ion implantation using this mask is performed in this order or in any order.

  Further preferably, in the method for manufacturing a solid-state imaging device of the present invention, the photodiode portion and the charge transfer portion of the pixel portion adjacent to the photodiode portion are formed via the groove and the channel stop portion.

  Further preferably, in the method for manufacturing a solid-state imaging device of the present invention, a step of forming an antireflection film on the photodiode portion through an interlayer film between the gate electrode forming step and the light shielding film forming step. The interlayer film is also formed on the side wall of the groove.

  An electronic information device according to the present invention uses the solid-state imaging device according to the present invention for an imaging unit, and thereby achieves the object.

  The operation of the present invention will be described below with the above configuration.

  Conventionally, a groove is formed in a wide range for embedding a gate electrode and a light shielding film, and in particular, a transfer gate portion, a charge transfer portion (CCD portion), and a channel stop portion are formed by performing ion implantation into a semiconductor substrate at the bottom of the groove. And a photodiode portion is formed in the semiconductor substrate other than the bottom of the groove. Thereafter, a gate electrode is embedded in the trench, and a light shielding film having an opening on the photodiode portion is embedded.

On the other hand, in the present invention, the width for embedding only the light-shielding film before ion implantation into the semiconductor substrate to form the photodiode portion, transfer gate portion, charge transfer portion, and channel stop portion. A narrow groove is formed, and a channel stop portion is formed at the bottom of the groove. Thereafter, a photodiode portion, a transfer gate portion, and a charge transfer portion are formed in the semiconductor substrate, and a gate electrode is formed on the transfer gate portion and the charge transfer portion, and then the photodiode portion is opened in the groove. A light shielding film is embedded.
As a result, the formation region of the charge transfer portion (CCD portion) of the present invention is formed at a shallower position than the formation region of the conventional charge transfer portion (CCD portion). Accordingly, the depth of the light shielding film embedded in the groove and the depth of the channel stop portion can be formed relatively deep with respect to the depth of the formation region of the charge transfer portion (CCD portion). In this way, by embedding the light shielding film in the groove deeper than conventional with respect to the charge transfer portion, oblique incident light incident on the semiconductor substrate is prevented by the light shielding film in the substrate embedded in the groove, As in the prior art, it is possible to prevent obliquely incident light from entering under the channel stop portion. For this reason, it becomes possible to suppress smear. Further, if the distance between the light shielding film and the oxide film of the semiconductor substrate is increased, the diffusely reflected light is attenuated before reaching the adjacent pixel portion, so that smear can be suppressed.

  Further, since the groove may have a width size for embedding only the light-shielding film, it is possible to minimize damage to the semiconductor substrate and reduce crystal defects as compared with the case of the prior art. It is possible to suppress defective white scratches.

  As described above, according to the present invention, illegal oblique light incident under the channel stop portion is embedded by embedding the light-shielding film in the groove of the semiconductor substrate at a position deeper than the prior art as viewed from the charge transfer portion. Smear can be suppressed by suppressing the intrusion of. In addition, since the light shielding film is formed deep inside the semiconductor substrate as described above, the distance to the adjacent pixel portion is increased, and the incident light due to the irregular reflection between the light shielding film and the semiconductor substrate is attenuated to reduce smear. Can be suppressed.

  Further, since smear can be suppressed, the opening of the light shielding film on the photodiode portion can be widened to receive light sufficiently, and the sensitivity characteristics can be improved.

  Furthermore, the groove width is sufficient to embed only the light-shielding film, and the groove width can be reduced as compared with the conventional case. Therefore, damage to the semiconductor substrate can be reduced and crystal defects can be reduced as compared with the conventional solid-state imaging device. As a result, it is possible to suppress the white defect which is a defect peculiar to the CCD and improve the characteristics.

  Embodiments of a solid-state imaging device and a method for manufacturing the same according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a longitudinal cross-sectional view illustrating an exemplary configuration of a main part of a solid-state imaging device according to an embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the component which has the same effect as the component of the conventional solid-state image sensor of FIG.

  In FIG. 1, the solid-state imaging device 20 of the present embodiment includes a plurality of photodiode units 3 (light receiving units) that photoelectrically convert incident light into a well region 2 provided on the surface of the Si substrate 1. A transfer gate unit 4 that reads out signal charges from the photodiode unit 3, a CCD unit 5 that is a charge transfer unit that transfers signal charges read out by the transfer gate unit 4 in a predetermined direction, and a photo of the pixel unit A channel stop unit 6 for separating the diode unit 3 and the CCD unit 5 of the adjacent pixel unit is provided.

  Above the Si substrate 1, a groove 7A is provided between the photodiode portion 3 of each pixel portion and the CCD portion 5 of the pixel portion adjacent thereto, and the channel stop portion 6 is the bottom of the groove 7A. Is provided. A gate electrode 9A is provided on the transfer gate portion 4 and the CCD portion 5 via a gate insulating film composed of a gate oxide film 8a and a gate nitride film 8b. On the gate electrode 9A, an interlayer insulating film composed of an interlayer oxide film 8c and an interlayer insulating film 8d is provided, and a light shielding film 11A having an opening on the photodiode portion 3 is provided thereon. The light shielding film 11A fills the groove 7A so as to cover the interlayer insulating film formed of the interlayer oxide film 8c and the interlayer insulating film 8d and to cover the CCD unit 5 from the side surface side of the photodiode unit 3 also from the lateral direction. Yes. An antireflection film 12 is provided in the opening A of the light shielding film 11A on the photodiode portion 3 so that light can be transmitted efficiently.

  In this case, the CCD unit 5 and the photodiode unit 3 are flush with each other. The predetermined depth of the groove 7A from the surface of the CCD unit 5 and the photodiode unit 3 may be formed to be equal to or deeper than the region depth of the CCD unit 5. Alternatively, the predetermined depth of the channel stop portion 6 is equal to the depth of the CCD portion 5 or deeper than the depth of the CCD portion 5. That is, the predetermined depth of the groove 7A may be adjusted to such an extent that the lower end of the region of the channel stop portion 6 is formed at a position deeper than the depth of the CCD portion 5 formed in a later process. Here, since the predetermined depth of the groove 7A is set to a position equivalent to the depth of the CCD section 5 formed in a later process, the lower end of the region of the channel stop section 6 is positioned deeper than the depth of the CCD section 5. Is located. As a result, the light shielding film 11A embedded in the groove 7A more reliably shields the oblique incident light from the opening A above the photodiode part 3 from being incident on the CCD part 5.

  Further, an interlayer insulating film composed of the interlayer oxide film 8c and the interlayer insulating film 8d is also formed on the sidewall of the groove 7A so that a gap is formed between the interlayer insulating films in the groove 7A. The light shielding film 11A is embedded in the gap of the groove 7A. Therefore, the width size (predetermined width) of the groove 7A is obtained by adding the film thickness of the light shielding film 11A necessary for light shielding and twice the film thickness of the interlayer insulating film composed of the interlayer oxide film 8c and the interlayer insulating film 8d. It is. The width size (predetermined width) of the groove 7A may be only the thickness of the light shielding film 11A necessary for light shielding.

  With the above configuration, the groove 7A and channel stop portion 6 forming step, the transfer gate portion 4 forming step, the CCD portion 5 forming step, and the photodiode portion 3 in the respective manufacturing steps of the solid-state imaging device 20 of the present embodiment are described below. 2A to FIG. 2D, FIG. 3 (A), FIG. 2 (D), FIG. 3 (A), FIG. 3 (D), FIG. 3 (D), FIG. a) to FIG. 3 (d), FIG. 4 (a) to FIG. 4 (d), FIG. 5 (a) to FIG. 5 (d), FIG. 6 (a) to FIG. 6 (f), FIG. Description will be made sequentially with reference to FIGS. 7E, 8 and 9A to 9D.

  First, as shown in FIG. 2A, after an oxide film 1a is formed on the Si substrate 1, a well region 2 composed of a P region is formed.

Next, as shown in FIG. 2B, a photoresist mask 13 is formed in a predetermined pattern on the Si substrate 1 in order to form a groove 7A having a predetermined width and a predetermined depth, as shown in FIG. Then, an etching process is performed on the Si substrate 1 to form a groove 7A having a predetermined width and a predetermined depth. At this time, it is desirable to selectively remove the oxide film 1a and the Si substrate 1 by dry etching. Although it is possible to remove the oxide film 1a by wet etching, it is desirable to use dry etching because etching proceeds in the lateral direction. As for the etching conditions, it is desirable that the selectivity between the material of the oxide film 1a and Si is 1 or more by using a fluorine gas. The Si substrate 1 can be etched using a mixed gas of HBr, Cl ₂ and O ₂ . Further, the width dimension of the groove 7A can be set in consideration of the characteristics (coverage and the like) of a film (here, an interlayer insulating film made up of the interlayer oxide film 8c and the interlayer insulating film 8d) to be laminated in a later step. desirable. It is desirable to adjust the predetermined depth of the groove 7A to such an extent that the channel stop portion 6 is formed at a position deeper than the depth of the CCD portion 5 formed in a later process.

  Further, as shown in FIG. 2D, ion implantation is performed using the photoresist mask 13 used in the etching process at the time of forming the groove 7A to form the channel stop portion 6 at the bottom of the groove 7A. If it is desired to set the width of the channel stop portion 6 separately from the width of the groove 7A, ion implantation may be performed by separately forming a photoresist mask.

  Further, the oxide film 1a and the photoresist mask 13 on the surface of the Si substrate 1 shown in FIG. 3A are removed, and oxidation is performed again as shown in FIG. 3B to form an oxide film 2b. At this time, only the portion of the groove 7A or only the channel stop portion 6 may be oxidized.

  Further, as shown in FIG. 3C, a photoresist mask 14 for forming the transfer gate portion 4 is formed in a predetermined pattern, and as shown in FIG. 3D, this photoresist mask 14 is used as a mask. Ion implantation is performed through the oxide film 2b to form the transfer gate portion 4.

  Further, the photoresist mask 14 for forming the transfer gate portion 4 is removed as shown in FIG. 4A, and the photoresist mask 15 for forming the CCD portion 6 is removed as shown in FIG. As shown in FIG. 4C, ions are implanted through the oxide film 2b using the photoresist mask 15 as a mask to form the transfer gate portion 4 and one of the adjacent grooves 7A. The CCD unit 5 is formed between the two. Thereafter, as shown in FIG. 4D, the photoresist mask 15 for forming the CCD portion 5 is removed.

  Further, as shown in FIG. 5A, a photoresist mask 16 for forming the photodiode portion 3 is formed in a predetermined pattern, and as shown in FIG. 5B, this photoresist mask 16 is masked. As a result, ion implantation is performed through the oxide film 2b to form the photodiode portion 3 between the transfer gate portion 4 and the other of the adjacent trenches 7A. Thereafter, as shown in FIG. 5C, the photoresist mask 16 for forming the photodiode portion 3 is removed. Further, the oxide film 2b is once removed as shown in FIG.

  Further, as shown in FIG. 6A, a gate oxide film 8a is formed on the substrate portion, and then a gate nitride film 8b is formed as shown in FIG. 6B. At this time, trench 7A is filled with gate oxide film 8a and gate nitride film 8b. Further, as shown in FIG. 6C, an N + -Poly Si film 9a to be the gate electrode 9A is deposited, and as shown in FIG. 6D, a photoresist mask 17 for forming the gate electrode 9A is formed. As shown in FIG. 6E, a gate electrode 9A is formed on the transfer gate portion 4 and the CCD portion 5 by performing an etching process using the photoresist mask 17 as a mask, as shown in FIG. At this time, the gate nitride film 8b buried in the trench 7A and the underlying gate oxide film 8a are also removed. Thereafter, as shown in FIG. 6F, the photoresist mask 17 for forming the gate electrode 9A is removed.

  Further, as shown in FIG. 7A, an interlayer oxide film 8c is formed over the gate electrode 9A, the photodiode portion 3, and the transfer gate portion 4 in the trench 7A, and thereafter, as shown in FIG. 7B. Nitride film 12a is formed on interlayer oxide film 8c. At this time, the interlayer oxide film 8c is also formed on the side wall of the groove 7A and affects the subsequent light shielding film forming process. Therefore, it is necessary to consider the thickness of the interlayer oxide film 8c (the interlayer insulating film in the groove 7A). 8 c). The nitride film 12a formed in the groove 7A need not be considered because it is removed when the antireflection film 12 on the photodiode portion 3 is processed in a later step. Further, as shown in FIG. 7C, a photoresist mask 18 for forming the antireflection film 12 is formed in a predetermined pattern, and as shown in FIG. 7D, this photoresist mask 18 is used as a mask. The antireflection film 12 is formed on the photodiode portion 3 by performing an etching process. Thereafter, as shown in FIG. 7E, the photoresist mask 18 for forming the antireflection film 12 is removed.

  Further, as shown in FIG. 8, an interlayer insulating film 8 d is formed on the entire surface of the substrate portion on the interlayer oxide film 8 c and the antireflection film 12. This interlayer insulating film 8d is also formed on the side wall of the groove 7A, as in the case of the interlayer oxide film 8c, and affects the subsequent light shielding film forming step. Therefore, the thickness of the interlayer insulating film 8d is taken into consideration. There is a need.

  Further, as shown in FIG. 9A, a light shielding film material 11a is formed on the interlayer insulating film 8d. In general, a metal film material such as tungsten is used as the light shielding film material 11a. However, the light shielding film material 11a may not be a metal film material as long as it has a light shielding property. At this time, the groove 7A is filled with the light shielding film material 11a in the gap of the interlayer insulating film 8d attached to the side wall. Thereafter, as shown in FIG. 9B, a photoresist mask 19 for forming a light shielding film is formed in a predetermined pattern having an opening on the photodiode portion 3, and this photo is shown in FIG. 9C. By performing an etching process using the resist mask 19 as a mask, the light shielding film material 11a on the photodiode portion 3 is removed, and the light shielding film 11A is formed as the opening A. Further, as shown in FIG. 9D, the photoresist mask 19 for forming the light shielding film 11A is removed, and the manufacture of the solid-state imaging device 20 of the present embodiment is completed.

  As described above, in the present embodiment, a plurality of photodiode portions 3 that photoelectrically convert incident light on the surface of the Si substrate 1, a transfer gate portion 4 that reads signal charges from these photodiode portions 3, and the transfer gate A CCD unit 5 serving as a charge transfer unit that transfers signal charges read out through the unit 4 in a predetermined direction is provided, and a gate insulating film (gate oxide film 8a) is provided on the transfer gate unit 4 and the CCD unit 5. In the solid-state imaging device 20 provided with the gate electrode 9A via the gate nitride film 8b), a groove 7A is formed in the Si substrate 1, and the photodiode portion 3 is formed on the surface of the Si substrate 1 where the groove 7A is formed. After forming the transfer gate part 4, the CCD part 5, and the gate electrode 9A, a light shielding film embedded in the groove 7A so as to cover the CCD part 5 in the lateral direction Forming a 1A.

  Thus, by embedding the light shielding film 11A deeply in the groove 7A of the Si substrate 1, the oblique incident light entering the Si substrate 1 is prevented from entering the CCD unit 5 from the channel stop unit 4 side, and smearing is performed. Can be suppressed. Further, since the light shielding film 11A is formed deep inside the semiconductor substrate 1 so as to cover the CCD portion 5 in the lateral direction, the distance to the adjacent pixel portion becomes long, and the irregular reflection between the light shielding film 11A and the semiconductor substrate 1 occurs. It is also possible to suppress smear by attenuating the incident light due to.

  Further, since smear can be suppressed, the opening A of the light shielding film 11A of the photodiode portion 3 can be widened to receive light sufficiently, and the sensitivity characteristics can be improved.

Further, the region where the groove 7A is formed is much narrower than that of the conventional solid-state imaging device 100, and damage to the Si substrate 1 can be reduced, so that crystal defects can be reduced. For this reason, it is possible to suppress white defects and improve characteristics.
Although not specifically described in the above embodiment, the solid-state imaging device 20 can be used in an imaging unit of an electronic information device such as a mobile phone device with a camera, a digital still camera, and a digital movie camera, and a light shielding film. Of the incident light incident on the photodiode unit 3 (light receiving unit) in the solid-state imaging device 20 through the opening A of 11A, oblique incident light that causes smearing toward the CCD unit 5 is embedded in the groove 7A. It can be prevented by the light shielding film 11A, and since the groove is provided only for shielding the oblique incident light, it can be configured to be smaller than the width of the groove for embedding the conventional gate electrode 9A, and can be formed on the semiconductor substrate. Damage can be minimized.
In the above-described embodiment, as the element part forming step, the transfer gate portion 4 is formed by ion implantation using a mask having a predetermined pattern, and one of the adjacent grooves 7A and the transfer gate portion 4 are formed. A CCD part forming step in which the CCD part 5 is formed by ion implantation using a mask having a predetermined pattern between the photodiode part 3 and the transfer gate part 4 between the other of the adjacent grooves 7A and the transfer gate part 4 is used. However, the present invention is not limited thereto, and is adjacent to the transfer gate portion forming step in which the transfer gate portion 4 is formed by ion implantation using a mask having a predetermined pattern. A mask of a predetermined pattern is placed on the CCD unit 5 between one of the grooves 7A and the transfer gate unit 4. CCD portion forming process using ion implantation and forming a photodiode portion 3 between the other of the adjacent grooves 7A and the transfer gate portion 4 by ion implantation using a mask having a predetermined pattern May be performed in any order.
As mentioned above, although this invention has been illustrated using preferable embodiment of this invention, this invention should not be limited and limited to this embodiment. It is understood that the scope of the present invention should be construed only by the claims. It is understood that those skilled in the art can implement an equivalent range based on the description of the present invention and the common general technical knowledge from the description of specific preferred embodiments of the present invention. Patents, patent applications, and documents cited herein should be incorporated by reference in their entirety, as if the contents themselves were specifically described herein. Understood.

  The present invention relates to a solid-state imaging device capable of imaging a subject and a manufacturing method thereof, and in the field of electronic information equipment such as a digital still camera, a digital movie camera, and a camera-equipped mobile phone using the solid-state imaging device as an imaging unit By embedding the light shielding film in the groove of the semiconductor substrate, the CCD part can be shielded from the side by the shallow part, and the intrusion of illegal oblique light incident on the CCD part from under the channel stop part is suppressed to suppress smear. Can do. Further, since the light shielding film is formed deep inside the semiconductor substrate as viewed from the CCD portion, the distance to the CCD portion of the adjacent pixel portion becomes longer as the CCD portion is shallower than in the conventional case. Smear can be suppressed by attenuating incident light due to irregular reflection between the light shielding film and the semiconductor substrate.

  Since smear can be suppressed as described above, the sensitivity characteristic can be improved by widening the opening of the light shielding film on the photodiode portion and allowing the photodiode portion to receive light sufficiently.

  Furthermore, since the region where the groove is formed is narrower than that of a conventional solid-state imaging device, and the crystal defects can be reduced by reducing damage to the semiconductor substrate, it is possible to improve the characteristics by suppressing white defects. .

It is a longitudinal cross-sectional view which shows the principal part unit structural example of the solid-state image sensor which concerns on embodiment of this invention. (A)-(d) is a longitudinal cross-sectional view for demonstrating the formation process of the groove | channel and channel stop part in each manufacturing process of the solid-state image sensor concerning embodiment of this invention. (A)-(d) is a longitudinal cross-sectional view for demonstrating the formation process of the transfer gate part in each manufacturing process of the solid-state image sensor concerning embodiment of this invention. (A)-(d) is a longitudinal cross-sectional view for demonstrating the formation process of the CCD part in each manufacturing process of the solid-state image sensor concerning embodiment of this invention. (A)-(d) is a longitudinal cross-sectional view for demonstrating the formation process of the photodiode part in the manufacturing process of each solid-state image sensor concerning embodiment of this invention. (A)-(f) is a longitudinal cross-sectional view for demonstrating the formation process of the gate electrode in each manufacturing process of the solid-state image sensor concerning embodiment of this invention. (A)-(e) is a longitudinal cross-sectional view for demonstrating the formation process of the anti-reflective film in each manufacturing process of the solid-state image sensor concerning embodiment of this invention. It is a longitudinal cross-sectional view for demonstrating the formation process of the interlayer insulation film in each manufacturing process of the solid-state image sensor concerning embodiment of this invention. (A)-(d) is a longitudinal cross-sectional view for demonstrating the formation process of the light shielding film in each manufacturing process of the solid-state image sensor concerning embodiment of this invention. It is a longitudinal cross-sectional view which shows the principal part unit structural example of the conventional solid-state image sensor. (A)-(c) is sectional drawing for demonstrating each manufacturing process (the 1) of the conventional solid-state image sensor. (A)-(c) is sectional drawing for demonstrating each manufacturing process (the 2) of the conventional solid-state image sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Si substrate 2 P-well area | region 1a, 2b Oxide film 3 Photodiode part 4 Transfer gate part 5 CCD part 6 Channel stop part 7A Groove 8a Gate oxide film 8b Gate nitride film 8c Interlayer oxide film 8d Interlayer insulation film 9a N + -Poly Si film 9A Gate electrode 11a Light-shielding film material 11A Light-shielding film 12 Antireflection film 12a Nitride film 13-19 Photoresist mask 20 Solid-state imaging device A Opening of light-shielding film

Claims (20)

In a solid-state imaging device in which a semiconductor substrate is provided with a photodiode unit for each pixel unit that photoelectrically converts incident light, and a charge transfer unit that can transfer a signal charge read from the photodiode unit.
A groove having a predetermined depth from the surface of the semiconductor substrate is provided between the pixel portion between the photodiode portion of the pixel portion and the charge transfer portion of the pixel portion adjacent to the pixel portion, and the groove for blocking oblique incident light. A solid-state imaging device in which a light-shielding film is provided so as to open the photodiode portion and cover at least the charge transfer portion.   2. The solid-state imaging device according to claim 1, wherein the predetermined depth of the groove is equal to or deeper than a depth of the charge transfer portion.   The solid-state imaging device according to claim 1, wherein the light shielding film in which the groove is embedded covers the charge transfer unit from a side surface side of the photodiode unit.   The solid-state imaging device according to claim 1, wherein the light shielding film embeds the groove so as to block oblique incident light from an opening above the photodiode portion.   The solid-state imaging device according to claim 1, wherein a surface of the charge transfer unit and a surface of the photodiode unit are configured to be flush with each other. The width of the groove is one of a film thickness dimension of the light shielding film necessary for light shielding and a film thickness dimension obtained by adding twice the film thickness dimension of the predetermined interlayer insulating film to the film thickness dimension of the light shielding film. The solid-state imaging device according to claim 1 or 2.   The channel stop part for separating between the photodiode part of the said pixel part and the electric charge transfer part of the pixel part adjacent to the said pixel part is provided in the predetermined depth from the bottom part of the said groove | channel. Solid-state image sensor.   The solid-state imaging device according to claim 7, wherein the predetermined depth of the channel stop portion is equal to or deeper than the depth of the charge transfer portion.   A transfer gate unit is provided between the photodiode unit and the charge transfer unit to enable signal charges to be read from the photodiode unit to the charge transfer unit. The transfer gate unit and the charge transfer unit are provided on the transfer gate unit and the charge transfer unit. The solid-state imaging device according to claim 1, wherein a gate electrode is provided via a gate insulating film.   The solid-state imaging device according to claim 9, wherein the photodiode portion and the groove are provided between adjacent gate electrodes. Forming a groove having a predetermined depth between regions to be each pixel portion of the semiconductor substrate, and forming a channel stop portion at the bottom of the groove and a channel stop portion forming step;
Photodiode unit for each pixel unit that photoelectrically converts incident light, a transfer gate unit that can read signal charges from the photodiode unit, and a charge that can transfer signal charges read through the transfer gate unit An element part forming step for forming a transfer part;
Forming a gate electrode on the transfer gate portion and the charge transfer portion via a gate insulating film; and
A method of manufacturing a solid-state imaging device, comprising: forming a light shielding film on the gate electrode and filling the groove, and forming a light shielding film on the photodiode portion.   In the step of forming the groove and the channel stop portion, the groove is formed to a predetermined depth by etching using a mask having a predetermined pattern, and the channel stop portion is formed by ion implantation into the bottom of the groove using the mask. The manufacturing method of the solid-state image sensor of Claim 11 formed.   The method for manufacturing a solid-state imaging device according to claim 11, wherein the etching process for forming the groove selectively removes the semiconductor substrate by dry etching.   In the case where an oxide film is formed on the surface of the semiconductor substrate, the etching condition is set such that the selectivity between the material of the oxide film and the material of the semiconductor substrate is 1 or more using a fluorine-based gas. The manufacturing method of the solid-state image sensor of Claim 12 or 13.   The method for manufacturing a solid-state imaging device according to claim 11, wherein a predetermined depth of the groove is equal to or greater than a depth position of the charge transfer unit.   The method for manufacturing a solid-state imaging device according to claim 11, wherein the predetermined depth of the channel stop portion is formed to be equal to or deeper than the depth of the charge transfer portion. The element part forming step includes
A transfer gate portion forming step of forming the transfer gate portion by ion implantation using a mask of a predetermined pattern;
A charge transfer portion forming step of forming the charge transfer portion by ion implantation using a mask of a predetermined pattern between one of adjacent grooves and the transfer gate portion;
The solid-state imaging according to claim 11, wherein a photodiode part forming step of forming the photodiode part by ion implantation using a mask having a predetermined pattern between the other of the adjacent grooves and the transfer gate part is performed in this order or in any order. Device manufacturing method.   The method of manufacturing a solid-state imaging device according to claim 17, wherein the photodiode portion and the charge transfer portion of the pixel portion adjacent to the photodiode portion are formed via the groove and the channel stop portion.   Between the gate electrode forming step and the light shielding film forming step, the method further includes a step of forming an antireflection film on the photodiode portion via an interlayer film, and the interlayer film is also formed on the sidewall of the groove. The manufacturing method of the solid-state image sensor of Claim 11.   The electronic information device which used the solid-state image sensor in any one of Claims 1-10 for the imaging part.

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