JP2008147409A - Solid-state image pickup device, its manufacturing method, and electronic information device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively perform condensing to a photoelectric conversion part in accordance with minuteness of an element, to secure a light receiving area, and to provide a small and highly sensitive solid-state image pickup element. <P>SOLUTION: Surface width (b) of a photodiode part PD has the same height as a surface of a light shielding film 9 or it is higher than the surface of the light shielding film 9 and a distance between an on-chip lens and the photodiode part becomes remarkably short compared to conventional technology. Thus, incident light can easily be condensed to the photodiode part even if an intra-layer lens is arranged in the photodiode part. A surface area of the photodiode part PD is equal to or larger than an area of an opening part (a) of the light shielding film 9. Even if a pixel size is made small by thinning the pixel, the light receiving area is not restricted by the opening area of the light shielding film 9. Thus, the larger light receiving area can be secured. When a surface (b) of the photodiode part PD has a hemispherical shape projected upward, it may play a role of the lens. Thus, incident light can efficiently be condensed to the photodiode part PD. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device such as a CCD type image sensor or a CMOS type image sensor composed of a semiconductor element that photoelectrically converts image light from a subject by a photoelectric conversion unit and images the same, a manufacturing method thereof, and a solid-state imaging device. The present invention relates to an electronic information device such as a digital camera such as a digital video camera and a digital still camera used as an image input device in an imaging unit, an image input camera, a scanner, a facsimile, and a camera-equipped mobile phone device.

  In recent years, there has been an increasing demand for higher definition of images of consumer digital still cameras and camera-equipped mobile phone devices. In solid-state image sensors such as CCD image sensors and CMOS image sensors mounted on these devices, The number of pixels is rapidly increasing.

  As described above, there is a strong demand for improvement in image quality for solid-state imaging devices, and in order to meet this demand, higher resolution with higher resolution by increasing the number of pixels and improvement in imaging sensitivity are required. It is necessary to plan. For this purpose, it is necessary to increase the pixel arrangement density and further reduce the size of the pixel portion while improving the imaging sensitivity.

  However, when the pixel size is reduced, the amount of light incident on the unit pixel is reduced, the sensitivity characteristic is lowered, and the area of the photodiode itself, which is a photoelectric conversion unit, is also reduced. The problem of deterioration in imaging sensitivity characteristics and saturation characteristics becomes obvious.

  In general, in a conventional CCD solid-state imaging device, a charge transfer unit for transferring a signal charge is provided adjacent to a photodiode unit where photoelectric conversion is performed, and light is not incident on this charge transfer unit. In addition, a light shielding film having an opening on the photodiode portion is provided. Here, in order to improve the sensitivity of the photodiode part, if the opening area of the light shielding film is increased to make the light receiving area too large, light is easily mixed into the charge transfer part and smearing is likely to occur. There is a limit to increasing the light receiving area corresponding to the aperture area.

  Therefore, conventionally, another method of forming another lens (inner layer lens) made of a light-transmitting material in a layer between the on-chip lens and the photodiode portion to improve the light collection efficiency to the photodiode portion. Is used. This intra-layer lens is a lens formed in the interlayer film directly above the photodiode portion where photoelectric conversion is performed, and the subject light condensed by the on-chip lens is further incident on this intra-layer lens, The object light is efficiently guided to the photodiode portion by being refracted by the upper surface side or lower surface side interface of the in-layer lens.

In Patent Documents 1 and 2, there is a method of forming an n-type impurity region constituting a photodiode part to a deeper region than in the past in order to effectively take out the charge photoelectrically converted in a deep portion of the silicon substrate as a signal charge. It is used. As a result, even if the area of the charge storage region is reduced, the photodiode capacitance increases, so that saturation characteristics are improved in a miniaturized photodiode.
In Patent Document 1, in the solid-state imaging device in which the photodiode portion is formed up to a deep region of the substrate, in order to effectively use oblique light, the light receiving portion in the substrate depth direction according to the position of the light receiving portion within the substrate surface. The potential profile is changed.
In Patent Document 2, the photodiode portion is composed of two layers of an N-type region that performs photoelectric conversion and an N-type single crystal semiconductor layer formed by epitaxial growth thereon, and whether the N-type single crystal semiconductor layer is silicon. Alternatively, it is made of a material having a higher light absorption coefficient. As a result, the photoelectric conversion efficiency of the photodiode portion is improved, and sensitivity is improved and smear is suppressed.
JP 2003-78125 A JP 9-213923 A

  However, the above-described conventional solid-state imaging device has the following problems.

  In recent years, pixel size has been increasingly miniaturized, and in particular, an ultra-fine one having a pixel pitch (cell pitch) of 2 μm or less has been proposed. It has become difficult to achieve high light collection efficiency by forming intra-layer lenses and on-chip lenses.

  In addition, the opening diameter of the light shielding film covering the periphery of the photodiode portion is also extremely small, being less than half of the pixel pitch. For example, when the pixel pitch is 2 μm, the opening of the light shielding film is considered in consideration of smearing. It is necessary to set the aperture to 600 nm or less. For this reason, there is a problem that visible red light having a long wavelength of 600 nm to 700 nm hardly reaches the photodiode portion which is a photoelectric conversion portion through the opening of the light shielding film. In particular, the alignment deviation between the opening portion of the light shielding film and the photodiode portion affects the imaging sensitivity and smear. Therefore, securing an alignment margin has been an important issue.

  As one of the countermeasures, in order to maintain sensitivity characteristics while miniaturizing the element, an n-type impurity region is formed to a deeper region as in Patent Documents 1 and 2 to increase the amount of signal charge that is photoelectrically converted. The sensitivity is increased, and as in Patent Document 2, the distance between the on-chip lens is reduced by growing the silicon layer that constitutes the photoelectric conversion portion to the vicinity of the light shielding film on the transfer electrode. Since the light collection efficiency to the photoelectric conversion unit is limited by the aperture diameter of the light shielding film, it was difficult to reduce the size and increase the sensitivity while further improving the light collection efficiency when miniaturizing the element. .

  As described above, there is a concern that the conventional solid-state imaging device has a limit in miniaturizing the device while maintaining high sensitivity characteristics.

  The present invention solves the above-described conventional problems, and can further improve the light collection efficiency even when the element is miniaturized. It is an object of the present invention to provide an electronic information device using an image element as an image input device in an imaging unit.

  The solid-state imaging device of the present invention is provided with a plurality of photoelectric conversion portions formed on a substrate and a light shielding portion having an opening corresponding to the photoelectric conversion portion, and the surface of the photoelectric conversion portion is the light shielding portion. The height of the surface is equal to or higher than the surface of the light shielding portion, and the above object is achieved.

  Preferably, the surface area of the photoelectric conversion unit in the solid-state imaging device of the present invention is formed wider than the area of the opening of the light shielding unit.

  Further preferably, the surface portion of the photoelectric conversion portion in the solid-state imaging device of the present invention is formed in a convex hemispherical or lens shape.

  Further preferably, in the solid-state imaging device of the present invention, at least a part of the surface of the photoelectric conversion unit is equal to or higher than the height position of the upper end of the opening of the light shielding unit. Is formed.

  Further preferably, in the solid-state imaging device according to the present invention, the opening of the light shielding part is formed of a hole, and the photoelectric conversion part is embedded in the hole.

  Further preferably, the surface of the photoelectric conversion portion in the solid-state imaging device of the present invention is formed in a planar shape or a spherical shape.

  Further preferably, in the solid-state imaging device of the present invention, the positional deviation in plan view of the surface portion of the photoelectric conversion unit is less affected by the alignment deviation at the time of patterning of the photoelectric conversion unit with respect to the alignment deviation of the opening of the light shielding unit. It has been adjusted to correct.

  Further preferably, the photoelectric conversion unit in the solid-state imaging device according to the present invention includes a photodiode unit, and the first conductivity formed selectively in the second conductivity type well region formed on the surface of the first conductivity type semiconductor substrate. Other than the type semiconductor region and the height of the surface of the light shielding part or higher than the surface of the light shielding part through the opening of the light shielding part on the first conductive type semiconductor region A first conductivity type semiconductor region.

  Still preferably, in a solid-state imaging device according to the present invention, the photodiode portion is a dark region composed of a high-concentration second conductive semiconductor region or an oxide film of the first conductive semiconductor layer on the other first conductive semiconductor region. It has a current blocking layer.

  Further preferably, in the solid-state imaging device of the present invention, the first conductive type semiconductor region is made of n-type silicon, and the high-concentration second conductive type semiconductor region is made of p-type silicon, or the first conductive type semiconductor The region is made of p-type silicon, and the high-concentration second conductivity type semiconductor region is made of n-type silicon.

  Further preferably, in the solid-state imaging device of the present invention, an insulating film is provided between the light shielding portion and the photoelectric conversion portion.

  Further preferably, in the solid-state imaging device of the present invention, an insulating film that covers the light shielding portion and has an opening corresponding to the first conductivity type semiconductor region is provided, and the first conductivity type semiconductor region and The other first conductivity type semiconductor region is formed on the insulating film.

  Further preferably, the light shielding portion in the solid-state imaging device of the present invention is also used as a light shielding film or a metal wiring layer.

  Further preferably, the light shielding portion in the solid-state imaging device of the present invention is an aluminum film, a refractory metal film made of titanium, titanium nitride, tungsten nitride, tungsten silicide or tungsten, or a composite film thereof.

  Further preferably, in the solid-state imaging device according to the present invention, a charge transfer unit that transfers a signal charge photoelectrically converted by the photoelectric conversion unit is provided adjacent to the photoelectric conversion unit, and the charge transfer unit is provided on the charge transfer unit. A charge transfer electrode for controlling the transfer of the signal charge by the charge transfer power unit is provided through the gate insulating film, and the light shielding unit is provided through the insulating film so as to cover the charge transfer electrode. Yes.

  Furthermore, preferably, a color filter layer is provided on the photoelectric conversion part in the solid-state imaging device of the present invention via a planarization layer.

  Further preferably, an on-chip lens is provided on the color filter layer in the solid-state imaging device of the present invention via an interlayer insulating layer.

  Further preferably, the solid-state imaging device of the present invention is a CCD image sensor, and has a light shielding film as the light shielding part, and a height position of a surface of the light shielding part is a height position of an uppermost surface of the light shielding film. It is.

  Further preferably, the metal wiring layer in the solid-state imaging device of the present invention is formed so as to avoid each of the plurality of photoelectric conversion portions as the light shielding portion, and an insulating film covering the metal wiring layer is formed. A semiconductor layer is filled in an opening provided in the insulating film up to a position in contact with the photoelectric conversion portion.

  Further preferably, the solid-state imaging device of the present invention is a CMOS image sensor, and has a multilayer wiring layer as the metal wiring layer, and the height position of the surface of the light shielding portion is the uppermost layer of the multilayer wiring layer. The height position of the surface.

  The method for manufacturing a solid-state imaging device according to the present invention includes a semiconductor region forming step of forming a semiconductor region constituting a photoelectric conversion portion on a semiconductor substrate, and a light shielding portion forming step of forming a light shielding portion having an opening with respect to the semiconductor region. And a semiconductor layer constituting the photoelectric conversion part on the light shielding part and the semiconductor region, wherein the surface of the semiconductor layer is equal to the height position of the surface of the light shielding part or from the surface of the light shielding part. Forming a semiconductor layer, and patterning the semiconductor layer into a predetermined shape so that the surface area of the semiconductor layer is equal to or larger than the area of the opening of the light shielding portion. In this way, the above object is achieved.

  The method for manufacturing a solid-state imaging device according to the present invention includes a semiconductor region forming step of forming a semiconductor region constituting a photoelectric conversion unit on a semiconductor substrate, and a light shielding unit forming a light blocking unit having an opening with respect to the photoelectric conversion unit An insulating film forming step of forming an insulating film covering the light shielding portion and having an opening on the semiconductor region; and a semiconductor layer further constituting the photoelectric conversion portion on the semiconductor region and the insulating film A semiconductor layer forming step in which a surface of the semiconductor layer is equal to or higher than a height position of the surface of the light shielding portion, and the semiconductor layer partially overlaps the insulating film. And a semiconductor layer patterning step of patterning the semiconductor layer into a predetermined shape so that the surface area of the semiconductor layer is equal to or larger than the area of the opening of the insulating film, and By the above eyes There is achieved.

  Preferably, in the method for manufacturing a solid-state imaging device according to the present invention, the semiconductor region and the semiconductor layer are formed of a silicon material.

Further preferably, after the semiconductor region forming step in the method for manufacturing a solid-state imaging device of the present invention, a charge for transferring a signal charge photoelectrically converted by the photoelectric conversion unit adjacent to the semiconductor region constituting the photoelectric conversion unit. A charge transfer portion forming step of forming a transfer portion; and a charge transfer electrode forming step of forming a charge transfer electrode on the charge transfer portion via a gate insulating film,
In the light shielding portion forming step, the light shielding portion is formed so as to cover the charge transfer electrode and to open the semiconductor region.

  Further preferably, the light shielding portion in the method for manufacturing a solid-state imaging device of the present invention is configured by a light shielding film or a metal wiring layer.

  The electronic information device of the present invention uses the solid-state imaging device of the present invention as an image input device in an imaging unit, and thereby achieves the above object.

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

  In the solid-state imaging device of the present invention, since the surface of the photodiode portion which is a photoelectric conversion portion is formed higher than the surface of the light shielding portion (for example, a light shielding film or a metal wiring layer), the on-chip lens and the photoelectric conversion Accordingly, the distance from the light source can be drastically shortened, and it is possible to easily collect the incident light on the photoelectric conversion part without providing an intra-layer lens.

  In addition, by increasing the surface area of the photoelectric conversion part larger than the area of the opening of the light shielding film, even if the pixel size is reduced, the area of the light receiving part is not limited by the opening area of the light shielding film as in the prior art. It is possible to secure a wide light receiving area and improve the light receiving efficiency and sensitivity.

  Furthermore, since the outermost surface of the photoelectric conversion part is formed in an upward convex hemisphere or lens shape and plays the role of a lens, more efficient condensing on the photoelectric conversion part becomes possible.

  Furthermore, by forming the surface of the photoelectric conversion portion in a planar shape, the interlayer insulating film thereon can be made thinner, and the distance between the on-chip lens and the photoelectric conversion portion can be made shorter.

  Furthermore, according to the method for manufacturing a solid-state imaging device of the present invention, the light shielding film covers a part of the photoelectric conversion unit due to a decrease in the opening area of the light shielding film, or the alignment deviation between the light shielding film and the photoelectric conversion unit. Even if this occurs, since the surface area of the photoelectric conversion unit can be increased or the position of the photoelectric conversion unit can be corrected thereafter, a small and highly sensitive solid-state imaging device can be easily manufactured.

  As described above, according to the present invention, since the surface of the photoelectric conversion unit is formed higher than the surface of the light shielding unit (for example, the light shielding film or the metal wiring layer), the distance between the on-chip lens and the photoelectric conversion unit is shortened. And the surface area of the photoelectric conversion portion can be made larger and wider than the area of the opening of the light shielding film. Accordingly, it is possible to effectively collect light on the photoelectric conversion unit corresponding to the miniaturization of the element, and to secure a light receiving area and to realize a small and highly sensitive solid-state imaging device. . Further, by forming the surface of the photoelectric conversion portion in a planar shape, the interlayer insulating film thereon can be made thinner and the distance between the on-chip lens and the photoelectric conversion portion can be made shorter. Furthermore, even if the light shielding film covers a part of the photoelectric conversion unit, or the alignment deviation between the light shielding film and the photoelectric conversion unit occurs, the surface area of the photoelectric conversion unit is subsequently increased or the photoelectric conversion unit Therefore, a small and highly sensitive solid-state imaging device can be manufactured.

Embodiments 1 and 2 when the solid-state imaging device of the present invention is applied to a CCD type image sensor and Embodiment 3 when it is applied to a CMOS type image sensor will be described in detail below with reference to the drawings.
(Embodiment 1)
FIG. 1 is a plan view illustrating a configuration example of a main part of a pixel unit in a solid-state imaging device according to Embodiment 1 of the present invention, and FIG. 2 is a vertical cross-sectional view in the AA ′ direction of FIG.

  In FIG. 1, the solid-state imaging device 20 according to the first embodiment includes a plurality of photodiode portions PD that are photoelectric conversion portions provided in a two-dimensional shape (or a matrix shape), and is adjacent to each photodiode portion PD. A vertical transfer unit V and a horizontal transfer unit H that transfer signal charges photoelectrically converted by the photodiode unit are provided.

  In FIG. 2, the solid-state imaging device 20 according to the first embodiment includes a low concentration p-type well region 2 on the surface portion of an n-type semiconductor substrate 1, and a photodiode PD in the low concentration p-type well region 2. N-type silicon region 3 and a charge transfer portion 4 made of an n-type semiconductor region in the vertical transfer portion V, and each charge transfer portion 4 and the n-type silicon region 3 of the photodiode PD of an adjacent pixel. Is provided with a pixel separation portion 5 made of a p-type semiconductor region. A gate electrode 7 serving as a charge transfer electrode is provided on the charge transfer unit 4 and the pixel separation unit 5 via a gate insulating film 6, and an insulating surface made of a thermal oxide film or the like is formed on the upper surface and side walls of the gate electrode 7. A light shielding film 9 as a light shielding portion made of a tungsten (W) film or the like is provided through the film 8. Further, a thin insulating film 10 made of an oxide film or the like is formed on the upper surface and side walls of the light shielding film 9.

  In the photodiode portion PD, an n-type silicon region 3 is selectively provided in a deep portion of the p-type well region 2, and an n-type silicon region 3 ′ extends upward through the opening a of the light shielding film 9 thereon. It is provided as follows. The n-type silicon region 3 ′ is provided so as to partially overlap the insulating film 10, and the upper surface thereof is formed to be higher than the upper surface of the light shielding film 9. As a result, the uppermost surface of the photodiode part PD is higher than the uppermost surface of the light shielding film 9, and the distance between the n-type silicon region 3 ′ as the light receiving part and the on-chip lens thereabove is significantly reduced. It has become. For this reason, in order to improve the light collection efficiency, light can be easily condensed on the surface of the photodiode part PD without providing an inner lens between the light receiving part (the surface part of the photodiode part PD) and the on-chip lens. be able to. Although not shown in FIG. 2, the on-chip lens is provided above the photodiode part PD in order to collect light on the photodiode part PD.

  Further, a part of the n-type silicon region 3 ′ is overlapped with the light shielding film 9 in plan view, and incident light is received at a position above the light shielding film 9 to perform photoelectric conversion. Smear that occurs when light is incident on a region other than can be significantly suppressed.

  Furthermore, the surface area of the width b of the photodiode part PD is formed larger than the area of the opening a (b> a) of the light shielding film 9. For this reason, even if the pixel size is reduced and made smaller, the area of the light receiving portion is not limited by the opening a of the light shielding film 9 as in the conventional solid-state imaging device, and a wider light receiving area can be secured.

  Further, the surface portion of the n-type silicon region 3 ′ constituting the photodiode portion PD has a hemispherical shape (or a lens shape) having a convex cross-sectional structure. Since this hemispherical portion serves as a convex lens, efficient condensing on the photodiode portion PD becomes possible.

  Here, the manufacturing method of the solid-state imaging device 20 of the first embodiment shown in FIGS. 1 and 2 will be described in detail with reference to FIGS.

  3 to 8 are main part longitudinal cross-sectional views in each manufacturing process for explaining the manufacturing method of the solid-state imaging device 20 of the first embodiment.

  First, as shown in the semiconductor region formation step, the charge transfer portion formation step, and the pixel separation portion formation step in FIG. 3, the p-type well region 2 is formed in the semiconductor substrate 1 made of, for example, n-type silicon. Further, an n-type impurity is selectively introduced into the p-type well region 2, and the n-type silicon region 3 of the semiconductor region that becomes the photodiode portion PD of the photoelectric conversion portion and the signal charges photoelectrically converted by the photoelectric conversion portion are supplied. A charge transfer portion 4 to be transferred is formed, and a p-type impurity is selectively introduced to form a pixel separation portion 5 on one side between the n-type silicon region 3 and the charge transfer portion 4. Each of these can be formed by a conventional method, and the process thereof is the same as a conventional general process, and thus detailed description thereof is omitted here.

  Next, as shown in the charge transfer electrode forming step in FIG. 4, a gate insulating film 6 made of, eg, a 30 nm-thick thermal oxide film is deposited on the surface portion of the semiconductor substrate 1 to separate the charge transfer portion 4 and the pixel separation. Patterning is performed in a predetermined shape that remains only on the portion 5. Further, a transfer gate electrode 7 made of polysilicon having a thickness of 200 nm, for example, is patterned through a gate insulating film 6 at positions corresponding to the charge transfer unit 4 and the vertical transfer unit V on the pixel separation unit 5 of the semiconductor substrate 1. Form. Although not shown in FIG. 4, the transfer gate electrode 7 is also formed at a position corresponding to the horizontal transfer portion H.

  Subsequently, for example, the entire surface of the substrate is thermally oxidized to form an insulating film 8 made of an oxide film having a thickness of about 50 nm on the top and side surfaces of the gate electrode 7 as shown in the light shielding film forming step of FIG. Thereafter, a light-shielding film 9 such as a tungsten (W) film having a thickness of 100 nm is formed on the entire surface of the substrate by, eg, CVD, and corresponds to the n-type silicon region 3 of the photodiode portion PD by photolithography, dry etching, or the like. An opening a is formed by opening the light shielding film 9 at the location. As the light shielding film 9, an aluminum (Al) film, a titanium (Ti) film that is a refractory metal film having a good light shielding property, a titanium nitride (TiN) film, a tungsten silicide (WSi) film, or tungsten (W). A membrane or a composite membrane thereof can be used.

  Thereafter, an insulating film 10 made of, for example, a 50 nm-thickness silicon oxide film is formed on the entire surface of the substrate so as to cover the light-shielding film 9, and a photodiode portion is formed as shown in the insulating film forming step of FIG. The insulating film 10 corresponding to the n-type silicon region 3 of the PD is selectively removed using a photolithography method and a dry etching method to form an opening, and the surface of the n-type silicon region 3 is exposed.

Further, as shown in the semiconductor layer formation step of FIG. 7, a photoelectric conversion unit is selectively formed on the exposed n-type silicon region 3 while including an N ⁺ impurity gas such as PH ₃ by using a selective epitaxial growth method. An n-type silicon layer 3 ′, which is a semiconductor layer constituting the, is formed. At the time of selective epitaxial growth, for example, disilane (Si ₂ H ₆ ) as a source gas is allowed to flow in an H ₂ atmosphere at a pressure of 11E-3 Pa to 5E-2 Pa at a temperature of 600 ° C. to 800 ° C. 3 ′ can be grown in the height direction until a part of the surface of the insulating film 10 is covered in plan view. Further, as a method for growing the silicon layer 3 ′, a silicon layer such as amorphous silicon may be formed on the entire surface of the substrate by, for example, a CVD method in which an n-type impurity is introduced, in addition to the selective epitaxial growth method. In this case, the film thickness is appropriately set so that the silicon layer 3 ′ is filled between the gate electrodes 7. Thus, the silicon layer 3 ′ of the semiconductor layer constituting the photoelectric conversion portion is formed on the exposed n-type silicon region 3 and the insulating film 10 of the semiconductor region, and the uppermost surface of the silicon layer 3 ′ is higher than the surface of the light shielding film 9. Higher than the thickness.

  Thereafter, as shown in the semiconductor layer patterning step of FIG. 8, the silicon region 3 ′ as the light receiving portion has a larger area than the opening a of the light shielding film 9, and a part thereof overlies the insulating film 10 on the light shielding film 9. A pattern is formed to wrap and the pixel portions are separated by a predetermined distance. At the time of separation processing of the silicon region 3 ′, the surface of the silicon region 3 ′ is processed into a convex hemisphere by, for example, a method of transferring a hemispherical (hemispherical) resist shape using a resist etching back method. be able to. In this way, the silicon region 3 ′ of the semiconductor layer partially overlaps the insulating film 10, and the silicon region 3 ′ has a surface area larger than the area of the opening of the insulating film 10 or the light shielding film 9. 'Is patterned into a predetermined shape (which may be square, rectangular or circular in plan view).

  Further, as shown in FIG. 2, a high-concentration p-type region 11 is selectively formed on the surface of the n-type silicon region 3 'to form a dark current prevention layer. Impurity introduction for forming this high-concentration p-type region is performed, for example, before the silicon layer 3 ′ is processed (impurity can be introduced after the processing). Further, although not shown here, the dark current prevention layer may be formed by, for example, oxidizing the surface of the n-type silicon region 3 ′ after separating the n-type silicon region 3 ′.

  Thereafter, a passivation film such as silicon nitride is formed by a plasma CVD method or the like, a color filter, an on-chip lens, or the like is formed to complete the production of the solid-state imaging device.

According to the above manufacturing method, even when the opening area of the light shielding film 9 is reduced and the light shielding film 9 covers a part of the photodiode part PD, or the alignment deviation between the light shielding film 9 and the photodiode part PD occurs. Then, since the surface area of the photodiode part PD can be increased, a small and highly sensitive solid-state imaging device 20 can be manufactured. The positional deviation of the surface portion of the n-type silicon region 3 ′ of the photoelectric conversion portion is corrected when the n-type silicon region 3 ′ is patterned in a predetermined shape with respect to the alignment displacement of the opening of the light shielding film 9. It can be adjusted to the normal position.
(Embodiment 2)
In the first embodiment, the case where the surface of the silicon layer 3 ′ of the photoelectric conversion unit is spherical and formed higher than the surface of the light shielding film 9 has been described, but in the second embodiment, the photoelectric conversion unit A case will be described in which the surface of the silicon layer 3 ′ is planar and is equivalent to the height position of the surface of the light shielding film 9.

  FIG. 9 is a vertical cross-sectional view illustrating an exemplary configuration of a main part of the pixel portion of the solid-state imaging device according to the second embodiment of the present invention, and is a vertical cross-sectional view in the same direction as the A-A ′ direction in FIG. 1.

  In FIG. 9, in the solid-state imaging device 30 according to the second embodiment, the photodiode portion PD is selectively provided with the n-type silicon region 3 of the photoelectric conversion portion in the deep portion of the p-type well region 2 and on the n-type silicon region 3. The silicon region 3 ′ is provided so as to extend upward through the opening a of the light shielding film 9. In this case, the opening “a” of the light shielding film 9 is formed of a hole, and the n-type silicon region 3 ′ fills the entire hole. The n-type silicon region 3 ′ is provided so as to partially overlap the insulating film 10 in plan view, and its upper surface is formed at a height position equivalent to the upper surface of the light shielding film 9. That is, the surface of the n-type silicon region 3 ′ of the photoelectric conversion portion is a position equivalent to the height position of the upper end portion of the opening a of the light shielding film 9. As a result, the uppermost surface of the photodiode part PD has the same height as the uppermost surface of the light shielding film 9, and the distance between the n-type silicon region 3 ′ serving as the light receiving part and the on-chip lens thereabove is increased. It is reduced compared to the conventional one. For this reason, in order to improve the light collection efficiency, light can be easily condensed on the surface of the photodiode part PD without providing an inner lens between the light receiving part (the surface part of the photodiode part PD) and the on-chip lens. be able to. Although this on-chip lens is not shown in FIG. 2, a color filter layer is provided above the photodiode portion PD via a flattening layer to collect light on the photodiode portion PD. It is provided on the filter layer via an interlayer insulating layer.

  Further, a part of the n-type silicon region 3 ′ is overlapped with the light shielding film 9 in plan view, and incident light is received at a position above the light shielding film 9 to perform photoelectric conversion. Smear that occurs when light is incident on a region other than can be significantly suppressed.

  Further, the surface area of the width b ′ of the photodiode part PD is formed larger than the area of the opening a (b> a) of the light shielding film 9. For this reason, even if the pixel size is reduced and made smaller, the area of the light receiving portion is not limited by the opening a of the light shielding film 9 as in the conventional solid-state imaging device, and a wider light receiving area can be secured.

  Further, the surface of the n-type silicon region 3 'constituting the photodiode part PD is planar. That is, the surface of the n-type silicon region 3 ′ is formed at a position equivalent to the height position of the upper end portion of the opening 9 a of the light shielding film 9, and the surface is planar. In this case, the position of the surface of the n-type silicon region 3 ′ in plan view is also corrected by correcting the misalignment during patterning of the predetermined shape of the n-type silicon region 3 ′ with respect to the misalignment of the opening of the light shielding film 9. The position can be adjusted.

  Furthermore, the light shielding film 9 can also be used as a metal wiring layer. Examples of the material of the light shielding film 9 include an aluminum film, a refractory metal film made of titanium, titanium nitride, tungsten nitride, tungsten silicide, or tungsten, or a composite film thereof.

  Further, since the surface of the n-type silicon region 3 ′ is formed in a planar shape, there are fewer steps, so that an interlayer insulating film (not shown) and a planarizing film thereon can be made thinner, and on-chip The distance between the lens and the photoelectric conversion unit can be made shorter.

As described above, according to the solid-state imaging devices 20 and 30 of the first and second embodiments, the surface width b of the photodiode portion PD is equal to the surface of the light shielding film 9 or higher than the surface of the light shielding film 9. Compared with technology, the distance between the on-chip lens and the photodiode portion is dramatically shortened, so that incident light can be easily condensed on the photodiode portion without providing an inner lens as in the prior art. it can. Further, the surface area of the photodiode portion PD is equal to or larger than the area of the opening a of the light shielding film 9, and even if the pixel size is reduced by reducing the pixel size, the light receiving area is not limited by the opening area of the light shielding film 9. A wider light receiving area can be ensured. Furthermore, if the surface b of the photodiode part PD is an upwardly convex hemisphere, this serves as a lens, so that incident light can be efficiently condensed onto the photodiode part PD. Therefore, in response to the miniaturization of the element, it is possible to effectively collect light on the photoelectric conversion unit, secure a light receiving area, and obtain the small and highly sensitive solid-state imaging elements 20 and 30.
(Embodiment 3)
In the first and second embodiments, the example in which the present invention is applied to the CCD image sensor has been described. However, the solid-state imaging device of the present invention is not limited to the CCD image sensor. In the third embodiment, the solid-state image sensor of the present invention is used. A case where the imaging element is applied to a CMOS image sensor having a multilayer wiring structure will be described.

  At the time of manufacturing the CMOS type image sensor, after forming the uppermost metal wiring layer (wiring 116 in FIG. 11 described later) and covering the wiring layer with an insulating film (interlayer insulating film 117 in FIG. 11 described later), Openings (holes 118 in FIG. 11 to be described later) are formed in the insulating films (interlayer insulating films 108, 111, 114, and 117 in FIG. 11 to be described later) until they are in contact with the photodiode portion PD (the optical sensor 104 in FIG. 11 to be described later). Form. A silicon layer (silicon layer 119 in FIG. 12 described later) is grown in the opening of the insulating film and formed so as to partially overlap the insulating film. Thus, by patterning in a predetermined shape in plan view, A silicon region 119A (n-type silicon region 3 ′ in the first embodiment) having a surface higher than the upper end portion of the wiring layer 116 (the light shielding film 9 in the first and second embodiments) and having a large surface area described later with reference to FIG. 13 is formed. can do.

  The above will be described in more detail.

  For example, as shown in the light shielding part forming step of FIG. 10, the CMOS type image sensor has an optical sensor 104, a floating diffusion part 106, a sensor peripheral circuit (details not shown), a charge transfer gate 105, a transistor on a semiconductor substrate 102. A gate 107 and a field oxide film 103, and a first interlayer insulating film 108 made of a silicon oxide film having a flattened surface are formed on the gate 107 and the field oxide film 103, and are connected to, for example, a floating diffusion portion 106 by a contact plug 109. A first-layer wiring, for example, an aluminum wiring 110 is formed.

  Further, on the interlayer insulating film 108 and the first layer wiring 110, a second interlayer insulating film 111 made of a silicon oxide film whose surface is also flattened is formed. On the interlayer insulating film 111 and the second-layer wiring 113, a third-layer interlayer insulating film 114 made of, for example, a silicon oxide film having a planarized surface is formed, and an uppermost layer (third layer) is formed thereon. A wiring 116 is formed. The wirings of the respective layers are connected by contact plugs. In the third embodiment, the wirings 110, 113, and 116 in the sensor peripheral portion are connected to each other by contact plugs 112 and 115. On the surface of the uppermost wiring 116 and the surface of the interlayer insulating film 114 exposed at the side of the wiring 116, an interlayer insulating film planarized by using, for example, a silicon oxide film and CMP (chemical mechanical polishing) or the like. 117 is formed.

  Here, although not shown in the drawings, in the conventional manufacturing method, after the light shielding portion forming step (the light shielding film forming step in the first and second embodiments, the multilayer wiring layer forming step in the third embodiment) in FIG. A CMOS image sensor is configured by forming a passivation film, a color filter, and an on-chip microlens thereon.

  In the third embodiment, first, after the wiring layer forming process of FIG. 10, as shown in the hole forming process of FIG. 11, the interlayer insulating films 117, 114, 111, and 108 are opened and connected on the sensor unit 104. A hole (contact hole) 118 to be formed is formed.

  Next, as shown in the semiconductor layer formation step in FIG. 12, a silicon layer 119 is formed on the interlayer insulating film 117 and the hole 118 (substrate portion), as in the case of the first embodiment, and the silicon layer 119 is formed in the hole. 118 is filled.

  Further, as shown in the semiconductor layer patterning step of FIG. 13, a predetermined shape (such as a square, a rectangle and a circle) is formed on the interlayer insulating film 117 so as to partially overlap in plan view. A silicon region 119A (for example, an n-type silicon region constituting the photodiode portion) having a surface higher than the uppermost wiring 116 and extending from the surface portion of the interlayer insulating film 117 to the sensor portion 104 can be formed.

  In the CMOS sensor formed in this way, the signal charge generated by receiving light by the sensor unit 104 through the silicon region 119A is supplied to the floating diffusion unit 106 by the charge transfer gate 105, and converted into a voltage signal in the floating diffusion unit 106. Then, it is supplied to the gate of an amplification transistor (not shown), where it is amplified and taken out as an imaging signal.

  Therefore, also in the third embodiment, the same effect as in the first and second embodiments can be obtained.

  In the first and second embodiments, the first conductivity type is n-type and the second conductivity type is p-type. However, the present invention is not limited to this, and the first conductivity type is p-type and the second conductivity type is n-type. You can also In the third embodiment, the same can be said as in the first and second embodiments.

Although not particularly described in the first to third embodiments, for example, a digital video camera or a digital still camera using any of the solid-state imaging devices 20 and 30 in the first to third embodiments as an imaging unit. An electronic information device having an image input device such as a digital camera, an image input camera such as a surveillance camera, a door phone camera, an in-vehicle camera, a television telephone camera, a scanner, a facsimile, or a camera-equipped mobile phone device will be described. The electronic information device according to the present invention performs high-quality image data obtained by using any one of the solid-state imaging devices 20 and 30 according to Embodiments 1 and 2 of the present invention as an imaging unit, and performs predetermined signal processing for recording. A memory unit such as a recording medium for recording data, a display means such as a liquid crystal display device that displays the image data on a display screen such as a liquid crystal display screen after performing predetermined signal processing for display, and the image data for communication At least one of a communication unit such as a transmission / reception device that performs communication processing after predetermined signal processing, and an image output unit that prints (prints) and outputs (prints out) the image data. .
As mentioned above, although this invention has been illustrated using preferable Embodiment 1-3 of this invention, this invention should not be limited and limited to this Embodiment 1-3. 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 1 to 3 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 such as a CCD type image sensor or a CMOS type image sensor composed of a semiconductor element that photoelectrically converts image light from a subject by a photoelectric conversion unit and images the same, a manufacturing method thereof, and a solid-state imaging device. The surface of the photoelectric conversion unit in the field of digital information cameras such as digital video cameras and digital still cameras used as image input devices and image information cameras, scanners, facsimiles, camera-equipped mobile phone devices, etc. However, since it is formed higher than the surface of the light shielding film, the distance between the on-chip lens and the photoelectric conversion part can be shortened, and the surface area of the photoelectric conversion part should be larger than the area of the opening of the light shielding film. Can do. Accordingly, it is possible to effectively collect light on the photoelectric conversion unit corresponding to the miniaturization of the element, and to secure a light receiving area and to realize a small and highly sensitive solid-state imaging device. . Further, by forming the surface of the photoelectric conversion portion in a planar shape, the interlayer insulating film thereon can be made thinner and the distance between the on-chip lens and the photoelectric conversion portion can be made shorter. Furthermore, even if the light shielding film covers a part of the photoelectric conversion unit, or the alignment deviation between the light shielding film and the photoelectric conversion unit occurs, the surface area of the photoelectric conversion unit is subsequently increased or the photoelectric conversion unit Therefore, a small and highly sensitive solid-state imaging device can be manufactured.

It is a top view which shows the principal part structural example of the pixel part of the solid-state image sensor which concerns on Embodiment 1 of this invention. It is a longitudinal cross-sectional view of the A-A 'direction of FIG. It is a principal part longitudinal cross-sectional view in the semiconductor region formation process, charge transfer part formation process, and pixel separation part formation process for demonstrating the manufacturing method of the solid-state image sensor which concerns on Embodiment 1 of this invention. It is a principal part longitudinal cross-sectional view in the charge transfer electrode formation process for demonstrating the manufacturing method of the solid-state image sensor which concerns on Embodiment 1 of this invention. It is a principal part longitudinal cross-sectional view in the light shielding film formation process for demonstrating the manufacturing method of the solid-state image sensor which concerns on Embodiment 1 of this invention. It is a principal part longitudinal cross-sectional view in the insulating film formation process for demonstrating the manufacturing method of the solid-state image sensor which concerns on Embodiment 1 of this invention. It is a principal part longitudinal cross-sectional view in the semiconductor layer formation process for demonstrating the manufacturing method of the solid-state image sensor which concerns on Embodiment 1 of this invention. It is a principal part longitudinal cross-sectional view in the semiconductor layer patterning process for demonstrating the manufacturing method of the solid-state image sensor which concerns on Embodiment 1 of this invention. It is a longitudinal cross-sectional view which shows the principal part structural example of the pixel part of the solid-state image sensor which concerns on Embodiment 2 of this invention, Comprising: It is a longitudinal cross-sectional view of the same direction as the A-A 'direction of FIG. It is a principal part longitudinal cross-sectional view in the wiring layer formation process for demonstrating the manufacturing method of the solid-state image sensor which concerns on Embodiment 3 of this invention. It is a principal part longitudinal cross-sectional view in the hole formation process for demonstrating the manufacturing method of the solid-state image sensor which concerns on Embodiment 3 of this invention. It is a principal part longitudinal cross-sectional view in the semiconductor layer formation process for demonstrating the manufacturing method of the solid-state image sensor which concerns on Embodiment 3 of this invention. It is a principal part longitudinal cross-sectional view in the semiconductor layer patterning process for demonstrating the manufacturing method of the solid-state image sensor which concerns on Embodiment 3 of this invention.

Explanation of symbols

1 n-type semiconductor substrate 2 p-type well region 3, 3 ′, 119A n-type silicon region constituting photodiode portion 4 charge transfer portion 5 pixel separation portion 6 gate insulating film 7 gate electrode 8, 10 insulating film 9 light shielding film 11 p-type high concentration region (dark current prevention layer)
20, 30 Solid-state imaging device V Vertical transfer portion H Horizontal transfer portion a Opening of light shielding film b Surface width of photodiode portion

Claims (26)

  A plurality of photoelectric conversion parts formed on the substrate and a light shielding part having an opening corresponding to the photoelectric conversion part are provided, and the surface of the photoelectric conversion part is equal to the height position of the surface of the light shielding part Or a solid-state imaging device formed higher than the surface of the light shielding portion.   The solid-state imaging device according to claim 1, wherein a surface area of the photoelectric conversion unit is formed wider than an area of an opening of the light shielding unit.   The solid-state imaging device according to claim 1, wherein a surface portion of the photoelectric conversion portion is formed in a convex hemispherical shape or a lens shape.   3. The solid according to claim 1, wherein at least a part of the surface of the photoelectric conversion unit is equal to or higher than a height position of an upper end of the opening of the light shielding unit. Image sensor.   5. The solid-state imaging device according to claim 1, wherein an opening of the light shielding portion is configured by a hole, and the photoelectric conversion unit embeds the entire inside of the hole.   The solid-state imaging device according to claim 4, wherein a surface of the photoelectric conversion unit is formed in a planar shape or a spherical shape.   The planar view position of the surface part of the said photoelectric conversion part is adjusted with respect to the alignment shift | offset | difference of the opening part of the said light-shielding part so that this alignment shift | offset | difference may be corrected at the time of patterning of this photoelectric conversion part. The solid-state image sensor described in 1.   The photoelectric conversion unit includes a photodiode unit, a first conductivity type semiconductor region selectively formed in a second conductivity type well region formed on the surface of the first conductivity type semiconductor substrate, and the first conductivity type semiconductor 2. Another first conductivity type semiconductor region formed on the region through the opening of the light shielding portion, the height of the surface of the light shielding portion is equal to or higher than the surface of the light shielding portion. 5. The solid-state image sensor according to 1 or 4.   The said photodiode part has a dark current prevention layer which consists of an oxide film of a high concentration 2nd conductivity type semiconductor region or the said 1st conductivity type semiconductor layer on said other 1st conductivity type semiconductor region. Solid-state image sensor.   The first conductivity type semiconductor region is made of n-type silicon, and the high concentration second conductivity type semiconductor region is made of p type silicon, or the first conductivity type semiconductor region is made of p type silicon, and the high concentration The solid-state imaging device according to claim 9, wherein the second conductivity type semiconductor region is made of n-type silicon.   The solid-state imaging device according to claim 1, wherein an insulating film is provided between the light shielding unit and the photoelectric conversion unit.   An insulating film covering the light shielding portion and having an opening corresponding to the first conductive type semiconductor region is provided, and the other first conductive type semiconductor is provided on the first conductive type semiconductor region and the insulating film. The solid-state imaging device according to claim 8, wherein a region is formed.   The solid-state imaging device according to claim 1, wherein the light-shielding portion is also used as a light-shielding film or a metal wiring layer.   9. The light shielding portion is an aluminum film, a refractory metal film made of titanium, titanium nitride, tungsten nitride, tungsten silicide or tungsten, or a composite film thereof. And the solid-state imaging device according to any one of 11 to 13.   Adjacent to the photoelectric conversion unit, a charge transfer unit that transfers the signal charge photoelectrically converted by the photoelectric conversion unit is provided, and the charge transfer unit is provided on the charge transfer unit through a gate insulating film. The solid-state imaging device according to claim 1, wherein a charge transfer electrode for controlling transfer of signal charge is provided, and the light shielding portion is provided via an insulating film so as to cover the charge transfer electrode.   The solid-state imaging device according to claim 1, wherein a color filter layer is provided on the photoelectric conversion unit via a flattening layer.   The solid-state imaging device according to claim 16, wherein an on-chip lens is provided on the color filter layer via an interlayer insulating layer.   16. A solid-state imaging device according to claim 13, wherein the image sensor has a light shielding film as the light shielding part, and a height position of a surface of the light shielding part is a height position of an uppermost surface of the light shielding film. element.   The metal wiring layer is formed as the light-shielding portion so as to avoid the plurality of photoelectric conversion portions, and the insulating film covering the metal wiring layer is insulated up to a position in contact with the photoelectric conversion portion. The solid-state imaging device according to claim 13, wherein a semiconductor layer is filled in an opening provided in the film.   20. A CMOS type image sensor, comprising a multilayer wiring layer as the metal wiring layer, wherein a height position of the surface of the light shielding portion is a height position of a surface of the uppermost layer of the multilayer wiring layer. The solid-state image sensor described in 1. A semiconductor region forming step of forming a semiconductor region constituting the photoelectric conversion portion on the semiconductor substrate;
A light shielding part forming step of forming a light shielding part having an opening with respect to the semiconductor region;
A semiconductor layer constituting the photoelectric conversion unit is further formed on the light shielding unit and the semiconductor region, and the surface of the semiconductor layer is equal to or higher than the height position of the surface of the light shielding unit. Forming a semiconductor layer; and
And a semiconductor layer patterning step of patterning the semiconductor layer into a predetermined shape so that the surface area of the semiconductor layer is equal to or larger than the area of the opening of the light shielding portion. A semiconductor region forming step of forming a semiconductor region constituting the photoelectric conversion portion on the semiconductor substrate;
A light shielding part forming step of forming a light shielding part having an opening with respect to the photoelectric conversion part;
An insulating film forming step of forming an insulating film covering the light shielding portion and having an opening on the semiconductor region;
A semiconductor layer constituting the photoelectric conversion unit is further formed on the semiconductor region and the insulating film, and the surface of the semiconductor layer is equal to or higher than the height position of the surface of the light shielding unit. Forming a semiconductor layer; and
A semiconductor layer that patterns the semiconductor layer into a predetermined shape so that the semiconductor layer partially overlaps the insulating film and the surface area of the semiconductor layer is equal to or larger than the area of the opening of the insulating film A manufacturing method of a solid-state image sensing device including a patterning process.   23. The method of manufacturing a solid-state imaging element according to claim 21, wherein the semiconductor region and the semiconductor layer are formed of a silicon material. A charge transfer unit forming step for forming a charge transfer unit for transferring a signal charge photoelectrically converted by the photoelectric conversion unit adjacent to a semiconductor region constituting the photoelectric conversion unit after the semiconductor region forming step; A charge transfer electrode forming step of forming a charge transfer electrode on the transfer portion via a gate insulating film,
23. The method of manufacturing a solid-state imaging element according to claim 21, wherein the light shielding part forming step forms the light shielding part so as to cover the charge transfer electrode and to open the semiconductor region.   23. The method of manufacturing a solid-state imaging device according to claim 21, wherein the light shielding part is configured by a light shielding film or a metal wiring layer.   An electronic information device using the solid-state imaging device according to claim 1 as an image input device in an imaging unit.

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