JP2011258729A - Solid-state imaging device and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid-state imaging device capable of obtaining sufficient sensitivity from light with any wavelength.SOLUTION: A solid-state imaging device 100 comprises: a semiconductor substrate 101; a wiring layer formed on the semiconductor substrate; a plurality of lower electrode layers 104b and 104g formed on the wiring layer, corresponding to a plurality of pixels; an organic photoelectric conversion film 106 formed on the plurality of lower electrode layers 104b and 104g; an upper electrode layer 107 formed on the organic photoelectric conversion film 106; and a plurality of color filters formed on the upper electrode layer 107, corresponding to the plurality of pixels. The plurality of color filters include a color filter 108g that mainly transmits light of a first wavelength, and a color filter 108b that mainly transmits light of a second wavelength which is shorter than the first wavelength. The thickness of the organic photoelectric conversion film 106 under the color filter 108b is thicker than that of the organic photoelectric conversion film 106 under the color filter 108g.

Description

  The present invention relates to a solid-state imaging device, and more particularly to a stacked solid-state imaging device having a photoelectric conversion film.

  An image sensor used in a digital still camera is a CCD sensor or a CMOS sensor in which pixel cells including photodiodes are arranged on a semiconductor substrate and charges generated by entering light into the photodiodes are read as signal charges. well known. In these solid-state imaging devices, photodiodes, wiring for driving circuits, and the like are formed on a semiconductor substrate. The wiring of the pixel cell portion has a layout in which an opening is formed on the photodiode for light reception.

  In recent years, with the increase in the number of pixels of a digital still camera or the like, the pixel cells of a solid-state imaging device have been miniaturized. As pixel cells become finer, there is a problem of sensitivity reduction due to narrowing of the wiring opening on the photodiode serving as the light receiving region.

  Therefore, in order to enlarge the light receiving region, a stacked solid-state imaging device has been proposed in which a photoelectric conversion layer is stacked above a semiconductor substrate on which photodiodes and circuit wiring are formed.

  An example of the configuration and operation of the stacked solid-state imaging device will be described with reference to FIG.

  8 includes a lower electrode 902 stacked on a semiconductor substrate 901, an organic photoelectric conversion film 903 made of an organic material stacked on the lower electrode 902, and the organic photoelectric conversion film 903. The photoelectric conversion elements including the upper electrode 904 stacked on the semiconductor substrate are arranged on a semiconductor substrate. By applying a voltage between the lower electrode 902 and the upper electrode 904 of the photoelectric conversion element, the signal charge generated in the organic photoelectric conversion film 903 moves to the lower electrode 902 and the upper electrode 904, and either electrode A signal corresponding to the charge transferred to is read by a circuit in the semiconductor substrate 901.

  Further, as a method for realizing a color solid-state imaging device, a structure in which a color filter that transmits only light of a specific wavelength for color separation is provided on the light incident surface side is generally used. A single-plate sensor in which color filters that transmit light, green light, and red light are regularly arranged is well known.

JP 2007-273894 A

  However, in the prior art, the quantum efficiency of the organic photoelectric conversion film and the reflectance of the pixel electrode are wavelength-dependent, so there is a problem that there is a difference in light use efficiency depending on the wavelength of light transmitted through each color filter. Exists.

  FIG. 10 is a graph showing the wavelength dependence of the light absorption rate of the organic photoelectric conversion film. In the figure, the horizontal axis indicates the wavelength of the incident light, and the vertical axis indicates the light absorption rate.

  FIG. 11 is a graph showing the wavelength dependence of the reflectance of the lower electrode. In the figure, the vertical axis represents the wavelength of incident light, and the vertical axis represents the reflectance.

  Specifically, FIG. 10 shows the wavelength dependence of the light absorption rate of quinacridone (film thickness 50 nm) used as an organic photoelectric conversion film. FIG. 11 shows the wavelength dependence of the reflectance when TiN is used for the lower electrode as an example of the metal used for the lower electrode.

  When the organic photoelectric conversion film is thickened, the ratio of light absorption increases, but for light with a wavelength of 500 nm to 580 nm, photoelectrons are generated on the surface of the organic photoelectric conversion film away from the lower electrode provided on the back surface of the organic photoelectric conversion film. (Signal charge) is generated. As a result, the organic photoelectric conversion film with low electron mobility has poor responsiveness. That is, sufficient sensitivity cannot be obtained for light having a wavelength of 500 nm to 580 nm.

  On the other hand, when the organic photoelectric conversion film is thinned, light with wavelengths of 400 nm to 500 nm and 580 nm to 700 nm passes through the photoelectric conversion film, so that sufficient sensitivity cannot be obtained. Among these, light having a wavelength of 580 nm to 700 nm is reflected by the lower electrode because the reflectance at the lower electrode is high as shown in FIG. 11, but light having a wavelength of 400 nm to 500 nm is shown in FIG. 11. In addition, since the reflectance at the lower electrode is low, the light is transmitted from the photoelectric conversion film to the lower electrode. Therefore, sufficient sensitivity cannot be obtained for light having a wavelength of 400 nm to 500 nm.

  In view of the above problems, an object of the present invention is to provide a solid-state imaging device capable of obtaining sufficient sensitivity for any wavelength of light and a method for manufacturing the same.

  In order to solve the above problems, a solid-state imaging device according to the present invention is a solid-state imaging device in which a plurality of pixels are arranged two-dimensionally, and includes a semiconductor substrate and a wiring layer formed on the semiconductor substrate. A plurality of lower electrode layers corresponding to the plurality of pixels formed on the wiring layer, a photoelectric conversion film formed on the plurality of lower electrode layers, and formed on the photoelectric conversion film. An upper electrode layer and a plurality of color filters corresponding to the plurality of pixels formed on the upper electrode layer, wherein the plurality of color filters mainly transmit light of a first wavelength. The photoelectric conversion film that includes a first color filter and a second color filter that mainly transmits light having a second wavelength shorter than the first wavelength, and is located below the second color filter The thickness is below the first color filter Larger than the thickness of the photoelectric conversion film located.

  Thereby, since the thickness of the photoelectric conversion film is set to a thickness according to the wavelength dependency of the quantum efficiency of the photoelectric conversion film and the wavelength dependency of the reflectance of the lower electrode layer, in any wavelength light, Sufficient sensitivity can be obtained.

  For example, when thinning the photoelectric conversion film of the pixel corresponding to the wavelength with high quantum efficiency of the photoelectric conversion film and the wavelength with high reflectance of the lower electrode layer, the signal charge is located near the lower electrode layer in the photoelectric conversion film. In addition, the electric field strength in the photoelectric conversion film can be increased, so that the signal charge read efficiency can be improved.

  On the other hand, when the photoelectric conversion film of the pixel corresponding to the wavelength with high quantum efficiency of the photoelectric conversion film and the wavelength with low reflectance of the lower electrode layer is made thicker than the photoelectric conversion film of other pixels, photoelectric conversion Low quantum efficiency in the film can be compensated.

  That is, sufficient sensitivity can be obtained for light of any wavelength.

  The plurality of lower electrode layers may include a first lower electrode positioned below the first color filter and a second lower electrode positioned below the second color filter, The upper surface of the second lower electrode may be closer to the semiconductor substrate than the upper surface of the first lower electrode.

  The lower surface of the upper electrode located below the second color filter may be farther from the semiconductor substrate than the lower surface of the upper electrode located below the first color filter.

  In addition, the thickness of the photoelectric conversion film positioned below a region including the boundary between adjacent color filters may be smaller than the thickness of the photoelectric conversion film positioned below another region.

  As a result, the path through which the signal charge generated in the photoelectric conversion film corresponding to one pixel moves to the photoelectric conversion film corresponding to another adjacent pixel is narrowed. In addition, the electric field strength in the photoelectric conversion film at the boundary between adjacent pixels is increased. As a result, it is possible to prevent the signal charge generated in one pixel from moving to a photoelectric conversion film corresponding to another adjacent pixel and being read as a false signal. That is, color mixing is prevented and spectral characteristics are improved.

  The quantum efficiency of the photoelectric conversion film at the first wavelength may be higher than the quantum efficiency of the photoelectric conversion film at the second wavelength.

  Thereby, in the photoelectric conversion film, the signal charge generated according to the light having the first wavelength with high quantum efficiency can be generated at a position close to the lower electrode layer, so that the read efficiency of the signal charge can be reliably improved. On the other hand, since the thickness of the photoelectric conversion film on which light of the second wavelength having a low quantum efficiency of the photoelectric conversion film is incident can be increased, the signal charge generated in the photoelectric conversion film can be increased, and the low quantum efficiency can be reduced. Can be reliably compensated.

  The reflectance of the plurality of lower electrode layers at the first wavelength may be higher than the reflectance of the plurality of lower electrode layers at the second wavelength.

  Thereby, even when the photoelectric conversion film located below the first color filter is thin, the light having the first wavelength incident on the photoelectric conversion film is reflected without being transmitted to the lower electrode layer. Therefore, even when the quantum efficiency of the photoelectric conversion film at the first wavelength is low, more signal charges can be generated in the photoelectric conversion film. That is, the sensitivity is improved.

  The solid-state imaging device manufacturing method according to the present invention is a manufacturing method of a solid-state imaging device in which a plurality of pixels are arranged two-dimensionally, the step of forming a wiring layer on a semiconductor substrate, and the wiring Forming a plurality of lower electrode layers corresponding to the plurality of pixels on the layer; forming a photoelectric conversion film on the plurality of lower electrode layers; and forming an upper electrode layer on the photoelectric conversion film. Forming a plurality of color filters corresponding to the plurality of pixels on the upper electrode layer, and the step of forming the plurality of color filters mainly includes a first wavelength. Forming a first color filter that transmits light, and forming a second color filter that mainly transmits light having a second wavelength shorter than the first wavelength, the photoelectric conversion In the step of forming a film, the second collar The thickness of the photoelectric conversion layer corresponding to the filter forms the first of said photoelectric conversion layer to be thicker than the thickness of the photoelectric conversion layer corresponding to the color filter.

  In addition, the step of forming the plurality of lower electrode layers includes the step of forming a second lower electrode corresponding to the second color filter and the step of forming the second lower electrode after the step of forming the second lower electrode. An insulating film may be formed on the insulating film, and a first lower electrode corresponding to the first color filter may be formed on the insulating film.

  Further, in the step of forming the plurality of lower electrode layers, the step of simultaneously forming the plurality of lower electrode layers and forming the photoelectric conversion film includes the step of forming the photoelectric conversion film having a uniform thickness on the plurality of lower electrode layers. You may include the process of forming a conversion film, and the process of selectively etching the photoelectric conversion film of the said uniform thickness corresponding to a said 1st color filter.

  Thereby, the manufacturing process can be simplified.

  By the above means, the present invention can realize a solid-state imaging device capable of obtaining sufficient sensitivity in any wavelength of light and a manufacturing method thereof.

It is a top view which shows the structure of the solid-state imaging device which concerns on 1st Embodiment. It is sectional drawing which shows the structure of the solid-state imaging device in the A-A 'cross section of FIG. 1A. It is process sectional drawing which shows an example of the manufacturing method of the solid-state imaging device which concerns on 1st Embodiment. It is process sectional drawing which shows another example of the manufacturing method of the solid-state imaging device which concerns on 1st Embodiment. It is sectional drawing which shows the structure of the solid-state imaging device which concerns on 2nd Embodiment. It is process sectional drawing which shows an example of the manufacturing method of the solid-state imaging device which concerns on 2nd Embodiment. It is sectional drawing which shows the structure of the solid-state imaging device which concerns on 3rd Embodiment. It is sectional drawing which shows the structure of the solid-state imaging device which concerns on 4th Embodiment. It is a cross-sectional schematic diagram of a solid-state imaging device according to a conventional embodiment. It is a top view which shows the example of arrangement | positioning of a color filter. It is a graph which shows the wavelength dependence of the light absorption rate of an organic photoelectric conversion film. It is a graph which shows the wavelength dependence of the reflectance of a lower electrode.

(First embodiment)
The solid-state imaging device according to the present embodiment is a solid-state imaging device in which a plurality of pixels are two-dimensionally arranged, and is formed on a semiconductor substrate, a wiring layer formed on the semiconductor substrate, and a wiring layer A plurality of lower electrode layers corresponding to the plurality of pixels, a photoelectric conversion film formed on the plurality of lower electrode layers, an upper electrode layer formed on the photoelectric conversion film, and an upper electrode layer A plurality of color filters corresponding to the plurality of pixels, wherein the plurality of color filters mainly includes a first color filter that transmits light of the first wavelength, and is mainly longer than the first wavelength. A photoelectric conversion film positioned below the first color filter, wherein the photoelectric conversion film positioned below the second color filter includes a second color filter that transmits light having a short second wavelength. Thicker than the thickness.

  Thereby, the solid-state imaging device according to the present embodiment can obtain sufficient sensitivity for light of any wavelength.

  Hereinafter, the solid-state imaging device according to the present embodiment will be described with reference to the drawings.

  FIG. 1A is a top view illustrating the configuration of the solid-state imaging device according to the first embodiment, and in particular, is a top view illustrating the configuration of an imaging region included in the solid-state imaging device.

  As shown in FIG. 1A, the solid-state imaging device 100 according to the present embodiment has a plurality of pixels arranged in a two-dimensional manner. The plurality of pixels include a pixel having a color filter 108r that transmits red light, a pixel having a color filter 108g that transmits green light, and a pixel having a color filter 108b that transmits blue light. including. For example, the color filter 108r that transmits red light mainly uses a wavelength of 580 to 700 nm as a transmission band, and the color filter 108g that transmits green light mainly uses a wavelength of 500 to 580 nm as a transmission band. The color filter 108b that transmits light mainly has a wavelength of 400 to 500 nm as a transmission band. These color filters 108r, 108g, and 108b are arranged, for example, according to a Bayer array.

  The color filter 108g that transmits green light corresponds to the first color filter of the present invention, and the color filter 108b that transmits blue light corresponds to the second color filter of the present invention. The light having a wavelength of 500 to 580 nm transmitted through the color filter 108g corresponds to the light having the first wavelength of the present invention, and the light having a wavelength of 400 to 500 nm transmitted through the color filter 108b has the second wavelength of the present invention. Corresponds to light.

  FIG. 1B is a cross-sectional view showing a configuration of the solid-state imaging device 100 in the A-A ′ cross section of FIG. 1A.

  A solid-state imaging device 100 shown in FIG. 1 includes a wiring portion including a metal wiring 102, an interlayer insulating film 103, and a contact via 104 a on a semiconductor substrate 101. An upper electrode 107 facing the lower electrodes 105b and 105g and the lower electrodes 105b and 105g and an organic photoelectric conversion film 106 between the lower electrodes 105b and 105g and the upper electrode 107 are provided above the wiring portion. Color filters 108b and 108g are provided above the upper electrode 107 so as to face the lower electrodes 105b and 105g, respectively. Further, the micro lens 109 may be formed above the color filters 108b and 108g. Note that the cross-sectional configuration of the pixel in which the color filter 108r is arranged is the same as the cross-sectional configuration in which the color filter 108g is arranged.

  That is, the solid-state imaging device 100 includes a semiconductor substrate 101, a plurality of metal wirings 102, an interlayer insulating film 103, a plurality of contact vias 104a to 104c, a plurality of lower electrodes 105b and 105g, and an organic photoelectric conversion film 106. And the upper electrode 107, the color filters 108b and 108g, and may further include a microlens 109.

  The semiconductor substrate 101 is, for example, a silicon substrate in which a plurality of impurity regions corresponding to a plurality of pixels are formed and holds signal charges generated by the organic photoelectric conversion film 106.

  The plurality of metal wirings 102 are stacked via an interlayer insulating film 103 and are electrically connected via contact vias 104a.

  The contact via 104b electrically connects the lower electrode 105b and the uppermost metal wiring 102 formed below the color filter 108b.

  The contact via 104c electrically connects the lower electrode 105g and the uppermost metal wiring 102 formed below the color filter 108g.

  The interlayer insulating film 103 is formed between the plurality of metal wirings 102 and between the plurality of lower electrodes 105b and 105g, and insulates between the plurality of metal wirings 102 and between the plurality of lower electrodes 105b and 105g.

  Each of the lower electrodes 105b and 105g corresponds to the lower electrode layer of the present invention, the lower electrode 105b is disposed below the color filter 108b, and the lower electrode 105g is disposed below the color filter 108g. Further, the upper surface of the lower electrode 105b is closer to the semiconductor substrate 101 than the upper surface of the lower electrode 105g. Although specific materials of the lower electrodes 105b and 105g will be described later, the lower electrodes 105b and 105g have a wavelength dependency of reflectance as shown in FIG. 11, for example. That is, the reflectance of the lower electrodes 105b and 105g at a wavelength of 500 to 580 nm is higher than the reflectance of the lower electrodes 105b and 105g at a wavelength of 400 to 500 nm. The lower electrode 105g corresponds to the first lower electrode of the present invention, and the lower electrode 105b corresponds to the second lower electrode of the present invention.

  The organic photoelectric conversion film 106 corresponds to the photoelectric conversion film of the present invention, is provided on the lower electrodes 105b and 105g, and generates a signal charge corresponding to the incident light by photoelectrically converting the incident light. The signal charges generated by the organic photoelectric conversion film 106 move to the lower electrodes 105b and 105g located below according to the bias voltage applied between the upper electrode 107 and the lower electrodes 105b and 105g, It moves to the semiconductor substrate 101 through the vias 104 a to 104 c and the plurality of metal wirings 102.

  The organic photoelectric conversion film 106 is made of, for example, quinacridone, and has the wavelength dependency of the light absorption rate as shown in FIG. That is, the light absorption rate of the organic photoelectric conversion film 106 at a wavelength of 500 to 580 nm is higher than the light absorption rate of the organic photoelectric conversion film 106 at a wavelength of 400 to 500 nm. In other words, the quantum efficiency of the organic photoelectric conversion film 106 at a wavelength of 500 to 580 nm is higher than the quantum efficiency of the organic photoelectric conversion film 106 at a wavelength of 400 to 500 nm.

  Here, the thickness of the organic photoelectric conversion film 106 positioned below the color filter 108b is thicker than the thickness of the organic photoelectric conversion film 106 positioned below the color filter 108g. In this way, by increasing the thickness of the organic photoelectric conversion film 106 positioned below the color filter 108b that transmits light having a short wavelength, the light incident on the organic photoelectric conversion film 106 through the color filter 108b is converted into the organic photoelectric conversion film 106b. It is possible to prevent a decrease in sensitivity due to permeation through the conversion film 106.

  On the other hand, by reducing the thickness of the organic photoelectric conversion film 106 positioned below the color filter 108g, the organic photoelectric conversion film 106 positioned below the color filter 108g can generate signal charges on the lower surface side. That is, a signal charge can be generated at a position close to the lower electrode 105g. As a result, the responsiveness to light transmitted through the color filter 108g is improved. Further, since the distance between the upper electrode 107 and the lower electrode 105g is reduced, the electric field strength in the organic photoelectric conversion film 106 located below the color filter 108g is increased. As a result, the reading efficiency of signal charges generated in the organic photoelectric conversion film 106 is increased.

  The upper electrode 107 corresponds to the upper electrode layer of the present invention, and is provided on the organic photoelectric conversion film 106. A bias voltage is applied between the lower electrodes 105g and 105g.

  The micro lens 109 is formed on the color filters 108b and 108g and collects incident light.

  In the solid-state imaging device 100 configured as described above, light is incident from the microlens 109 side, only light having a specific wavelength is transmitted through the color filters 108b and 108g, and signal charges corresponding to the light are transmitted to the organic photoelectric conversion film 106. Occurs. Then, by applying a bias voltage between the lower electrodes 105b and 105g and the upper electrode 107, an electric field is applied in the organic photoelectric conversion film 106, and the generated signal charges are moved to the lower electrodes 105b and 105g. Thus, the signal corresponding to the signal charge can be extracted to the outside.

  The organic photoelectric conversion film 106 described above has a structure having two or more types of film thickness, and has a structure in which the film thickness is thick under the color filter 108b that transmits light having a short wavelength (400 nm to 500 nm).

  As described above, the solid-state imaging device 100 according to the present embodiment is a solid-state imaging device in which a plurality of pixels are two-dimensionally arranged, and includes a semiconductor substrate 101 and a wiring layer formed on the semiconductor substrate 101. A lower electrode 105b and 105g corresponding to a plurality of pixels, an organic photoelectric conversion film 106 formed on the lower electrode 105b and 105g, and an organic photoelectric conversion film 106 formed on the wiring layer. The upper electrode 107 and the color filters 108b and 108g formed on the upper electrode 107 and corresponding to a plurality of pixels are provided. The color filters 108b and 108g mainly transmit light having a wavelength of 500 to 580 nm. A color filter 108g, and a color filter 108b that mainly transmits light having a wavelength of 400 to 500 nm. The thickness of the organic photoelectric conversion film 106 located is thicker than the thickness of the organic photoelectric conversion film 106 located below the color filter 108 g.

  With this configuration, the organic photoelectric conversion film 106 has a high quantum efficiency pixel that absorbs light with a wavelength of 500 nm to 580 nm, and the lower electrode 105b and 105g have high reflectivity and a pixel that absorbs light with a wavelength of 580 nm to 700 nm. The organic photoelectric conversion film 106 can be made thin, signal charges can be generated at a position close to the lower electrode 105g, and the electric field strength in the organic photoelectric conversion film 106 can be increased, so that the signal charge read efficiency is improved. Can be made.

  On the other hand, for light having a wavelength of 400 nm to 500 nm, the low quantum efficiency in the organic photoelectric conversion film 106 can be compensated by making the film thickness of the organic photoelectric conversion film 106 thicker than that of other pixels.

  In other words, a signal charge corresponding to light having a wavelength of 500 nm to 580 nm incident on the organic photoelectric conversion film 106 via the color filter 108 g can be generated at a position near the lower electrode 105 g of the organic photoelectric conversion film 106. . Further, the electric field strength generated between the lower electrode 105g and the upper electrode 107 can be increased. Thereby, the reading efficiency of the signal charge is improved.

  In addition, for light of 580 nm to 700 nm incident on the organic photoelectric conversion film 106 through the color filter 108r, the reflectance of light of 580 nm to 700 nm of the lower electrode positioned below the color filter 108r is high. Have the same effect.

  On the other hand, by increasing the film thickness of the organic photoelectric conversion film 106 positioned below the color filter 108b, the lower electrode 105b of light having a wavelength of 400 to 500 nm incident on the organic photoelectric conversion film 106 through the color filter 108b. As compared with the case where the film thickness is thin, the conversion efficiency of signal charges generated for incident light can be improved.

  That is, the solid-state imaging device 100 according to the first embodiment can obtain sufficient sensitivity for light of any wavelength.

  Next, a method for manufacturing the above-described solid-state imaging device 100 will be described. Here, the manufacturing method of the solid-state imaging device 100 is partially different depending on the material used for the lower electrodes 105b and 105g.

  First, a manufacturing method when TiN, Al, or a compound containing Al is used as the material of the lower electrode will be described.

  FIG. 2 is a process cross-sectional view illustrating an example of a manufacturing method of the solid-state imaging device 100 according to the first embodiment. Specifically, the lower electrodes 105b and 105g are made of TiN, Al, or a compound containing Al, and a plurality of lower electrodes 105b and 105g having different distances from the surface of the semiconductor substrate 101 are formed, whereby the organic photoelectric conversion film 106 is formed. Sectional drawing of each process of the 1st manufacturing method example of 1st Embodiment which gives multiple film thickness is shown.

  First, as shown in FIG. 2A, a circuit for driving the solid-state imaging device 100 is formed by laminating a metal wiring 102, an interlayer insulating film 103, and a contact via 104 a on a semiconductor substrate 101. Form. By using copper (Cu) as the material of the metal wiring 102 and the contact via 104a, the interlayer insulating film 103 can be used in a damascene process, and the wiring can be miniaturized.

  Next, as shown in FIG. 2B, after an interlayer insulating film 103 is deposited and a via hole is formed by etching, a material for the contact via 104b is deposited to fill the via hole. Thereafter, the contact via 104b is formed by CMP (Chemical Mechanical Polishing). Examples of the material of the contact via 104b include W, Al, and TiN. Note that the laminated wiring layer 120 composed of the interlayer insulating film 103, the metal wiring 102, and the contact vias 104a and 104b configured in the steps up to here corresponds to the wiring layer of the present invention.

  Next, as shown in FIG. 2C, the lower electrode 105b is formed. Further, the metal wiring 102 is formed so as to be electrically connected to the lower electrode 105g formed at a position facing the color filter 108g that transmits light having a long wavelength. Here, examples of the material of the lower electrode 105b include TiN, Al, and a compound containing Al as described above.

  Next, as shown in FIGS. 2D and 2E, the contact via 104c is formed in the same process as the process shown in FIGS. An electrode 105g is formed.

  Next, as shown in FIG. 2F, the interlayer insulating film 103 on the lower electrode 105b is selectively etched to expose the lower electrode 105b.

  Next, as shown in FIG. 2G, an organic photoelectric conversion film 106 is evaporated or deposited above the lower electrodes 105b and 105g. Planarization may be performed after the organic photoelectric conversion film 106 is deposited or deposited.

  Next, as shown in FIG. 2H, after the upper electrode 107 is formed on the organic photoelectric conversion film 106, the color filters 108b and 108c are formed. Note that the microlens 109 may be formed above the color filters 108b and 108c.

  As described above, the solid-state imaging device 100 shown in FIGS. 1A and 1B can be manufactured.

  That is, the manufacturing method of the solid-state imaging device 100 according to the present embodiment includes the step of forming the laminated wiring layer 120 on the semiconductor substrate 101, the lower electrode 105b corresponding to a plurality of pixels on the laminated wiring layer 120, and A step of forming 105 g, a step of forming the organic photoelectric conversion film 106 on the lower electrodes 105 b and 105 g, a step of forming the upper electrode 107 on the organic photoelectric conversion film 106, and a plurality of layers on the upper electrode 107. Forming the color filters 108b and 108g corresponding to the pixels. The step of forming the color filters 108b and 108g mainly includes the step of forming the color filter 108g that transmits light having a wavelength of 500 to 580 nm. And a step of forming a color filter 108b that transmits light having a wavelength of 400 to 500 nm, and the organic photoelectric conversion film 1 In the step of forming a 6, the thickness of the photoelectric conversion layer corresponding to the color filter 108b is to form the organic photoelectric conversion film 106 to be thicker than the thickness of the organic photoelectric conversion film 106 corresponding to the color filter 108 g.

  Specifically, the step of forming the lower electrodes 105b and 108g includes the step of forming the lower electrode 105b corresponding to the color filter 108b and the step of forming the lower electrode, and then the interlayer insulating film 103 on the laminated wiring layer 120. And a step of forming a lower electrode 105b corresponding to the color filter 108g on the interlayer insulating film 103.

  Thus, the upper surface of the lower electrode 105b can be formed closer to the semiconductor substrate 101 than the upper surface of the lower electrode 105g. Therefore, the thickness of the organic photoelectric conversion film 106 corresponding to the color filter 108b is reduced by depositing or depositing the organic photoelectric conversion film 106 on the lower electrodes 105b and 105g so that the surface is substantially flat. It becomes thicker than the thickness of the organic photoelectric conversion film 106 corresponding to 108 g.

  Therefore, it is possible to manufacture the solid-state imaging device 100 that can obtain sufficient sensitivity for light of any wavelength.

  Next, a manufacturing method when Cu or a compound containing Cu is used as the material of the lower electrode will be described.

  FIG. 3 is a process cross-sectional view illustrating another example of the method for manufacturing the solid-state imaging device 100 according to the present embodiment. Specifically, by using Cu or a compound containing Cu for the lower electrodes 105b and 105g and forming a plurality of lower electrodes 105b and 105g having different distances from the surface of the semiconductor substrate 101, the film of the organic photoelectric conversion film 106 is formed. Sectional drawing of each process of the 2nd manufacturing method example of 1st Embodiment which gives multiple thickness is shown.

  First, as shown in FIG. 3A, a metal wiring 102, an interlayer insulating film 103, and a contact via 104a are stacked on a semiconductor substrate 101 to form a circuit for driving the solid-state imaging device 100. By using copper (Cu) as the material of the metal wiring 102 and the contact via 104a, the interlayer insulating film 103 can be used in a damascene process, and the wiring can be miniaturized. Furthermore, in the present embodiment, the same copper (Cu) process can be used up to the subsequent step of the lower electrode 105g, so that the process can be simplified.

  Next, as shown in FIG. 3B, an interlayer insulating film 103 is deposited, and a part of the deposited interlayer insulating film 103 is removed by etching to form a groove. The interlayer insulating film 103 to be removed corresponds to the contact via 104b and the lower electrode 105b to be formed in a later process.

  Next, as shown in FIG. 3C, after filling the groove formed in the interlayer insulating film 103 with Cu or a metal material containing Cu, the contact via 104b and the lower electrode 105g are formed by CMP.

  Next, as shown in FIGS. 3D and 3E, the contact via 104c and the lower electrode 105g are formed in the same procedure as in FIGS. 3B to 3C.

  Next, as shown in FIG. 3 (f) to FIG. 3 (h), it is shown in FIG. 1A and FIG. 1B by the same procedure as the steps of the manufacturing method shown in FIG. 2 (f) to FIG. The solid-state imaging device 100 can be obtained.

(Second Embodiment)
The solid-state imaging device according to the second embodiment is substantially the same as the solid-state imaging device 100 according to the first embodiment, but the lower surface of the upper electrode located below the color filter 108b is the color filter 108g. The distance from the semiconductor substrate 101 is lower than the lower surface of the upper electrode located below, and the distance from the upper surface of the lower electrode 105g to the semiconductor substrate 101 is substantially equal to the distance from the upper surface of the lower electrode 105b to the semiconductor substrate 101. Different.

  FIG. 4 is a cross-sectional view illustrating a configuration of a solid-state imaging device according to the second embodiment. This cross section corresponds to the A-A 'cross section of FIG. 1A.

  In the solid-state imaging device 200 illustrated in FIG. 4, the lower electrodes 105 b and 105 g are formed at the same height from the surface of the semiconductor substrate 101 in all the pixels as compared with the solid-state imaging device 100 according to the first embodiment. In other words, the lower electrodes 105b and 105g are formed in the same wiring layer.

  The solid-state imaging device 200 includes an organic photoelectric conversion film 206 instead of the organic photoelectric conversion film 106 and an upper electrode 207 instead of the upper electrode 107, as compared with the solid-state imaging device 100 according to the first embodiment. In the upper electrode 207, the lower surface of the upper electrode 207 located below the color filter 108b is farther from the semiconductor substrate 101 than the lower surface of the upper electrode 207 located below the color filter 108g. In other words, in Embodiment 1, the organic photoelectric conversion film 106 is formed so that the thickness of the organic photoelectric conversion film positioned below the color filter 108b is larger than the thickness of the organic photoelectric conversion film positioned below the color filter 108g. The bottom surface was uneven. In contrast, in the second embodiment, the organic photoelectric conversion film is thicker than the organic photoelectric conversion film positioned below the color filter 108g so that the thickness of the organic photoelectric conversion film positioned below the color filter 108b is larger. 206 has irregularities on its upper surface.

  Therefore, the solid-state imaging device 200 according to the second embodiment has the same effects as the solid-state imaging device 100 according to the first embodiment. That is, sufficient sensitivity can be obtained for light of any wavelength.

  As described above, in the solid-state imaging device 200 according to the second embodiment, the lower surface of the upper electrode 207 located below the color filter 108b is different from the solid-state imaging device 100 according to the first embodiment. The distance from the semiconductor substrate 101 to the lower surface of the upper electrode 207 positioned below 108g, the distance from the upper surface of the lower electrode 105g to the semiconductor substrate 101, and the distance from the upper surface of the lower electrode 105b to the semiconductor substrate 101 are substantially equal. Equal points are different.

  Next, a method for manufacturing the above-described solid-state imaging device 200 will be described.

  FIG. 5 is a process cross-sectional view illustrating an example of a manufacturing method of the solid-state imaging device 200 according to the second embodiment.

  First, as shown in FIGS. 5A and 5B, the same process as that of the solid-state imaging device 100 according to the first embodiment shown in FIGS. 2A and 2B is performed. A stacked wiring layer 120 is formed on the semiconductor substrate 101. However, the laminated wiring layer 120 shown in FIG. 5B also includes a contact via 104c connected to the lower electrode 105g formed in the subsequent process. That is, the laminated wiring layer 120 shown in FIG. 5B includes the interlayer insulating film 103, the metal wiring 102, and the contact vias 104a to 104c.

  Next, as shown in FIG. 5C, the lower electrodes 105b and 105g are formed simultaneously by the same process as the process of the solid-state imaging device 100 according to the first embodiment shown in FIG.

  Next, as shown in FIG. 5D, an organic photoelectric conversion film 206 'is deposited or deposited. Here, the organic photoelectric conversion film 206 ′ formed by vapor deposition or deposition has a uniform thickness in any of the plurality of pixels. In other words, the upper surface of the organic photoelectric conversion film 206 'is the same plane.

  Next, as shown in FIG. 5E, only the organic photoelectric conversion film 206 'above the lower electrode 105g is thinned by selectively etching the organic photoelectric conversion film 206'. As a result, the organic photoelectric conversion film 206 is formed. In other words, by selectively etching the organic photoelectric conversion film 206 ′ corresponding to the color filter 108g, the thickness of the organic photoelectric conversion film 206 positioned below the color filter 108b is reduced to an organic level positioned below the color filter 108g. An organic photoelectric conversion film 206 thicker than the thickness of the photoelectric conversion film 206 is formed.

  Next, as shown in FIG. 5F, the upper electrode 207 and the color filters 108b and 108g are formed on the organic photoelectric conversion film 206 as in the first embodiment. The micro lens 109 may be formed above the color filters 108b and 108g.

  As described above, the solid-state imaging device 200 shown in FIG. 4 can be manufactured.

  That is, the manufacturing method of the solid-state imaging device 200 according to the present embodiment is lower than the manufacturing method of the solid-state imaging device 100 according to the first embodiment shown in FIGS. Are formed in the same process. Thereafter, a step of forming an organic photoelectric conversion film 206 ′ having a uniform thickness on the lower electrodes 105b and 105g, and an organic photoelectric conversion film 206 ′ having a uniform thickness corresponding to the color filter 108g are selectively etched. Forming an organic photoelectric conversion film 206.

  Thereby, according to the manufacturing method of the solid-state imaging device 200 which concerns on this embodiment, the process of forming the lower electrodes 105b and 105g is reduced compared with the manufacturing method of the solid-state imaging device 100 which concerns on 1st Embodiment. Therefore, the manufacturing process can be simplified.

(Third embodiment)
The solid-state imaging device according to the third embodiment is substantially the same as the solid-state imaging device 100 according to the first embodiment, but is a photoelectric conversion film positioned below a region including the boundary between adjacent color filters. Is different in that it is thinner than the thickness of the photoelectric conversion film located below the other region.

  FIG. 6 is a cross-sectional view illustrating a configuration of a solid-state imaging device according to the third embodiment. This cross section corresponds to the A-A 'cross section of FIG. 1A.

  In the solid-state imaging device 300 according to the third embodiment, in the solid-state imaging device 100 according to the first embodiment, the thickness of the organic photoelectric conversion film 306 at the portion corresponding to the boundary between adjacent pixels is the highest compared to the other portions. It is a thinning structure.

  In other words, the solid-state imaging device 300 according to the present embodiment includes an organic photoelectric conversion film 306 instead of the organic photoelectric conversion film 106 and an upper electrode instead of the upper electrode 107, as compared with the solid-state imaging device 100 illustrated in FIG. 307. In the organic photoelectric conversion film 306, the thickness below the region including the boundary between the adjacent color filter 108b and the color filter 108g is thinner than the thickness below the other regions. Accordingly, the upper electrode 307 below the region including the boundary between the adjacent color filter 108b and the color filter 108g is thickened.

  As a result, the path through which the signal charge generated in the organic photoelectric conversion film 306 corresponding to one pixel moves to the organic photoelectric conversion film 306 corresponding to another adjacent pixel becomes narrow. In addition, the electric field strength in the organic photoelectric conversion film 306 at the boundary between adjacent pixels is increased. Thereby, it is possible to prevent the signal charge generated in one pixel from moving to the organic photoelectric conversion film 306 corresponding to another adjacent pixel and being read as a false signal. That is, the solid-state imaging device 300 according to the third embodiment prevents color mixing and improves spectral characteristics.

  Note that FIG. 6 shows a structure in which the organic photoelectric conversion film 306 is selectively etched to reduce the thickness of the organic photoelectric conversion film 306 at the boundary between adjacent pixels. A structure in which a difference in film thickness of the organic photoelectric conversion film 306 is provided by forming a step on the base of 306 may be employed. In other words, in the solid-state imaging device 300 illustrated in FIG. 6, the thickness of the organic photoelectric conversion film 306 below the region including the boundary between the adjacent color filters 108 b and 108 g is reduced by providing a difference in height on the upper surface. On the other hand, the thickness of the organic photoelectric conversion film 306 below the region may be reduced by increasing the thickness of the interlayer insulating film 103 below the region including the boundary between the adjacent color filters 108b and 108g.

  Further, the solid-state imaging device 300 according to the third embodiment is organic, which is located below a region including the boundary between the adjacent color filters 108b and 108g with respect to the configuration of the solid-state imaging device 100 according to the first embodiment. Although the thickness of the photoelectric conversion film 306 is reduced, the photoelectric conversion located below the region including the boundary between the adjacent color filters 108b and 108g with respect to the solid-state imaging device 200 according to the second embodiment. The structure which makes the film thickness thin may be sufficient. In this case, the same effect as that of the third embodiment is obtained.

(Fourth embodiment)
The solid-state imaging device according to this embodiment is different from the solid-state imaging device according to the first embodiment in that the lower electrode layer is formed simultaneously with the wiring layer of the drive circuit.

  FIG. 7 is a cross-sectional view illustrating a configuration of a solid-state imaging device according to the fourth embodiment.

  The solid-state imaging device 400 according to the fourth embodiment shown in the figure has a lower electrode 405b instead of the lower electrode 105b, as compared with the solid-state imaging device 100 according to the first embodiment. The lower electrode 405b is formed simultaneously with the metal wiring 102 of the drive circuit of the solid-state imaging device 400.

  According to the configuration of the solid-state imaging device 400 according to the present embodiment, the organic photoelectric conversion film 106 can have a plurality of film thicknesses without significantly increasing the number of steps. In addition, the space below the lower electrode 405b can be used as a wiring region of the drive circuit of the solid-state imaging device 400, and the degree of freedom of wiring layout can be expanded.

  As described above, the solid-state imaging device and the manufacturing method thereof according to the present invention have been described based on the embodiments. However, the present invention is not limited to these embodiments. Unless it deviates from the meaning of this invention, the form which made the said embodiment the various deformation | transformation which those skilled in the art think, and the form constructed | assembled combining the component in a different embodiment are also contained in the scope of the present invention.

  For example, in the above embodiment, the structure below the color filter 108g and the structure below the color filter 108r are the same, but they may be different structures. Specifically, the film thickness of the organic photoelectric conversion film positioned below the color filter 108g may be different from the film thickness of the organic photoelectric conversion film positioned below the color filter 108r.

  When the present invention is used in a stacked solid-state imaging device having an organic photoelectric conversion film, the generated signal charge can be efficiently read regardless of the wavelength of light transmitted through the color filter. It can utilize for imaging devices, such as.

100, 200, 300, 400, 900 Solid-state imaging device 101, 901 Semiconductor substrate 102 Metal wiring 103 Interlayer insulating film 104a, 104b, 104c Contact via 105b, 105g, 405b, 902 Lower electrode 106, 206, 306, 903 Organic photoelectric Conversion film 107, 207, 307, 904 Upper electrode 108b, 108g, 108r Color filter 109 Micro lens 120 Multilayer wiring layer

Claims (9)

A solid-state imaging device in which a plurality of pixels are arranged two-dimensionally,
A semiconductor substrate;
A wiring layer formed on the semiconductor substrate;
A plurality of lower electrode layers corresponding to the plurality of pixels formed on the wiring layer;
A photoelectric conversion film formed on the plurality of lower electrode layers;
An upper electrode layer formed on the photoelectric conversion film;
A plurality of color filters corresponding to the plurality of pixels formed on the upper electrode layer;
The plurality of color filters are:
A first color filter that mainly transmits light of a first wavelength;
A second color filter that mainly transmits light having a second wavelength shorter than the first wavelength;
The thickness of the photoelectric conversion film positioned below the second color filter is thicker than the thickness of the photoelectric conversion film positioned below the first color filter. The plurality of lower electrode layers are:
A first lower electrode located below the first color filter;
A second lower electrode located below the second color filter,
The solid-state imaging device according to claim 1, wherein an upper surface of the second lower electrode is closer to the semiconductor substrate than an upper surface of the first lower electrode. 3. The solid-state imaging according to claim 1, wherein a lower surface of the upper electrode positioned below the second color filter is farther from the semiconductor substrate than a lower surface of the upper electrode positioned below the first color filter. apparatus. 4. The thickness of the photoelectric conversion film positioned below a region including a boundary between adjacent color filters is thinner than the thickness of the photoelectric conversion film positioned below another region. The solid-state imaging device described. 5. The solid-state imaging device according to claim 1, wherein a quantum efficiency of the photoelectric conversion film at the first wavelength is higher than a quantum efficiency of the photoelectric conversion film at the second wavelength. The solid-state imaging device according to claim 1, wherein a reflectance of the plurality of lower electrode layers at the first wavelength is higher than a reflectance of the plurality of lower electrode layers at the second wavelength. . A method of manufacturing a solid-state imaging device in which a plurality of pixels are arranged two-dimensionally,
Forming a wiring layer on the semiconductor substrate;
Forming a plurality of lower electrode layers corresponding to the plurality of pixels on the wiring layer;
Forming a photoelectric conversion film on the plurality of lower electrode layers;
Forming an upper electrode layer on the photoelectric conversion film;
Forming a plurality of color filters corresponding to the plurality of pixels on the upper electrode layer,
The step of forming the plurality of color filters includes:
Forming a first color filter that mainly transmits light of a first wavelength;
Forming a second color filter that mainly transmits light of a second wavelength shorter than the first wavelength,
In the step of forming the photoelectric conversion film,
The photoelectric conversion film is formed such that the photoelectric conversion film corresponding to the second color filter is thicker than the photoelectric conversion film corresponding to the first color filter. Method. The step of forming the plurality of lower electrode layers includes:
Forming a second lower electrode corresponding to the second color filter;
A step of forming an insulating film on the wiring layer after the step of forming the second lower electrode;
The method for manufacturing a solid-state imaging device according to claim 7, further comprising: forming a first lower electrode corresponding to the first color filter on the insulating film. In the step of forming the plurality of lower electrode layers, the plurality of lower electrode layers are formed simultaneously,
The step of forming the photoelectric conversion film includes:
Forming the photoelectric conversion film having a uniform thickness on the plurality of lower electrode layers;
The method for manufacturing a solid-state imaging device according to claim 7, further comprising: selectively etching the photoelectric conversion film having a uniform thickness corresponding to the first color filter.

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