Abstract:
A solid-state imaging device includes: a semiconductor substrate on which multiple pixels are provided, each of the pixels having a photoelectric converting section; multiple insulating films stacked on the semiconductor substrate; a wiring film provided between the multiple insulating films; an intralayer lens provided for each of the photoelectric converting section between the multiple insulating films; an optical filter provided for each of the photoelectric converting section on the insulating film; and an on-chip lens provided for each of the photoelectric converting section on the optical filter, wherein at least one of the intralayer lenses and on-chip lens has a different structure for each pixel in accordance with the characteristic of the optical filter.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
       [0001]    The present invention contains subject matter related to Japanese Patent Applications JP 2006-274219 filed in the Japanese Patent Office on Oct. 5, 2006, the entire contents of which being incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a solid state imaging device such as a CMOS image sensor including an optical filter such as a color filter having different wavelength characteristics for multiple pixels and further to an imaging apparatus for a camera or a cellular phone, for example, including the solid state imaging device. 
         [0004]    2. Description of the Related Art 
         [0005]    A solid state imaging device having an intralayer lens or an on-chip lens forming a micro lens surface corresponding to a photoreceptive section of each pixel has been provided in a CMOS image sensor from the past. For example, multiple wiring layers and interlayer insulating films are stacked on a semiconductor substrate having a photodiode and a transistor, and an intralayer lens is placed therebetween. Furthermore, an on-chip color filter and a micro lens are placed thereon through a flattening film (refer to JP-A-2004-304148, for example). 
         [0006]      FIGS. 12 and 13  are section diagrams showing an example of the stacked layer structure in a CMOS image sensor in the past. 
         [0007]    In the figures, a photoreceptive section  211  of photodiodes of multiple pixels is provided in the upper layer part of a silicon substrate  200 . Notably, a pixel transistor circuit included in each pixel is omitted in  FIGS. 12 and 13 . 
         [0008]    A flattening film (interlayer insulating film)  216  and wiring  210  is provided on the upper surface of the silicon substrate  200  through a gate insulating film  200 A and a gate electrode, not shown, and an interlayer lens  209  is provided thereon. Two flattening films (interlayer insulating films)  215  and  214  and wiring  208  and  206  are provided thereon, and an uppermost flattening film  213  is provided thereon. 
         [0009]    Then, color filters  202 ,  203  and  204  corresponding to respective pixels are placed on the flattening film  213 . Notably,  FIG. 12  shows a section where the red filter  202  and the green filter  203  appear, and  FIG. 13  shows a section where the green filter  203  and the blue filter  204  appear. 
         [0010]    An on-chip lens  201  is further provided on the color filters  202 ,  203  and  204  through a protective film. 
       SUMMARY OF THE INVENTION 
       [0011]    By the way, in the CMOS image sensor as described above, many wiring films are provided on the photoreceptive section, and the distance between the uppermost micro lens (top lens) and the photoreceptive section increases. Then, the light gathering states of pixels for different colors may not be optimized in accordance with the differences in wavelength of light through the color filters. Therefore, the light gathering states at central and peripheral photoreceptive section for each color differ due to the aperture of a camera lens and/or differences in incident angle at and the central and peripheral photoreceptive section. As a result, an unevenness of color shading, for example, may occur. 
         [0012]    This is also true in a case with an intralayer lens as in the example in the past. 
         [0013]    Accordingly, it is desirable to provide a solid state imaging device and imaging apparatus that can optimize the input light characteristic to the photoreceptive section of an optical filter provided in each pixel. 
         [0014]    According to an embodiment of the invention, there is provided a solid-state imaging device including a semiconductor substrate on which multiple pixels are provided, each of the pixels having a photoelectric converting section, multiple insulating films stacked on the semiconductor substrate, a wiring film provided between the multiple insulating film, an intralayer lens provided for each of the photoelectric converting section between the multiple insulating film, an optical filter provided for each of the photoelectric converting section on the insulating film, and an on-chip lens provided for each of the photoelectric converting section on the optical filter, wherein at least one of the intralayer lenses and on-chip lens has a different structure for each pixel in accordance with the characteristic of the optical filter. 
         [0015]    According to another embodiment of the invention, there is provided an imaging apparatus including a solid state imaging device imaging a subject, an imaging optical system forming a subject image in a photoreceptive section of the solid state imaging device, a drive/control section driving the imaging optical system, a signal processing section performing signal processing on the output signal from the solid state imaging device and generating an image signal, a recording section recording the image signal generated by the signal processing section, an output section outputting the image signal generated by the signal processing section, and an operating section inputting signals for controlling an imaging operation, wherein the solid state imaging device comprises a semiconductor substrate on which multiple pixels are provided, each of the pixels having a photoelectric converting section, multiple insulating films stacked on the semiconductor substrate, a wiring film provided between the multiple insulating film, an intralayer lens provided for each of the photoelectric converting section between the multiple insulating film, an optical filter provided for each of the photoelectric converting section on the insulating film, and an on-chip lens provided for each of the photoelectric converting section on the optical filter, in which at least one of the intralayer lenses and on-chip lens has a different structure for each pixel in accordance with the characteristic of the optical filter. 
         [0016]    The solid state imaging device and imaging apparatus according to the embodiments of the invention can optimize the input light characteristic to the photoreceptive section of an optical filter provided for each pixel since the intralayer lens and on-chip lens have a different structure for each pixel in accordance with the characteristic of the optical filter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a section view showing the stacked layer structure of a CMOS image sensor according to an embodiment of the invention; 
           [0018]      FIG. 2  is a section view showing the stacked layer structure of a CMOS image sensor according to the embodiment of the invention; 
           [0019]      FIG. 3  is a block diagram schematically showing the CMOS image sensor shown in  FIG. 1 ; 
           [0020]      FIG. 4  is a circuit diagram showing the pixel construction of the CMOS image sensor shown in  FIG. 1 ; 
           [0021]      FIG. 5  is a plan view showing a pattern of top lenses in the CMOS image sensor shown in  FIG. 1 ; 
           [0022]      FIG. 6  is a plan view showing a pattern of color filter layers in the CMOS image sensor shown in  FIG. 1 ; 
           [0023]      FIG. 7  is a plan view showing the layout of the micro lens layers in accordance with the construction of the wiring and color filter in the CMOS image sensor shown in  FIG. 1 ; 
           [0024]      FIG. 8  is a plan view showing the layout of the micro lens layers in accordance with the construction of the wiring and color filter in the CMOS image sensor shown in  FIG. 1 ; 
           [0025]      FIG. 9  is a plan view showing the layout of the micro lens layers in accordance with the construction of the wiring and color filter in the CMOS image sensor shown in  FIG. 1 ; 
           [0026]      FIG. 10  is a plan view showing apart of the photoreceptive section and pixel transistor on the silicon substrate in the CMOS image sensor shown in  FIG. 1 ; 
           [0027]      FIG. 11  is a block diagram showing a construction example of a camera apparatus including the CMOS image sensor shown in  FIG. 1  as an imaging section; 
           [0028]      FIG. 12  is a section view showing an example of the stacked layer structure of a CMOS image sensor in the past; and 
           [0029]      FIG. 13  is a section view showing the example of the stacked layer structure of the CMOS image sensor in the past. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0030]      FIGS. 1 and 2  are section views showing an example of the stacked structure in a solid state imaging device (CMOS image sensor) according to an embodiment of the invention. 
         [0031]      FIG. 3  is a block diagram schematically showing the CMOS image sensor shown in  FIG. 1 , and  FIG. 4  is a circuit diagram showing the pixel construction of the CMOS image sensor shown in  FIG. 1 . 
         [0032]      FIG. 5  is a plan view showing a pattern of top lenses in the CMOS image sensor shown in  FIG. 1 ,  FIG. 6  is a plan view showing a pattern of color filter layers in the CMOS image sensor shown in  FIG. 1 .  FIGS. 7 to 9  are plan views showing the layouts of the micro lens layers in accordance with the construction of the wiring and color filters. 
         [0033]      FIG. 10  is a plan view showing a part of the photoreceptive section and pixel transistor on the silicon substrate. 
         [0034]    The section views shown in  FIGS. 1 and 2  are taken by the lines A-A′ and B-B′ in  FIGS. 5 to 10 . 
         [0035]    A CMOS image sensor according to the embodiment will be first described with reference to  FIGS. 3 and 4 . 
         [0036]    As shown in  FIG. 3 , the CMOS image sensor has an imaging area  10  and a peripheral circuit area  20  on one chip. The imaging area  10  includes a pixel array section in which multiple pixels  11  including photodiodes (photoelectric converting sections) are placed in the two-dimensional direction. The peripheral circuit area  20  is provided outside of the imaging area  10 . 
         [0037]    The peripheral circuit area  20  includes a vertical pixel select/drive circuit  21 , a column signal processing section  22 , a horizontal scan circuit  23 , an output processing section  24  and a timing generator  25 . The vertical pixel select/drive circuit  21  reads out a pixel signal from each pixel column by supplying a control pulse to the pixel array section. The column signal processing section  22  performs signal processing such as noise processing on the column signal read out from the pixel array section. The horizontal scan circuit  23  horizontally transfers the pixel signal processed by the column signal processing section  22 . The output processing section  24  outputs the pixel signal transferred from the horizontal scan circuit  23  as an image signal. The timing generator  25  supplies a timing signal to the sections. 
         [0038]    As shown in  FIG. 4 , each of the pixels  11  of the imaging area  10  has pixel transistors including a photodiode  31 , a readout transistor (transfer gate)  32 , an amplifier transistor  33 , a select transistor  34 , and a reset transistor  35 . The photodiode  31  generates a signal charge in accordance with the amount of received light. The readout transistor (transfer gate)  32  reads out the signal charge of the photodiode  31  to an FD (floating diffusion). The amplifier transistor  33  generates a pixel signal in accordance with the potential of the FD. The select transistor  34  selects the output timing of a pixel signal. The reset transistor  35  resets the FD. Each of the pixels  11  further includes wiring and other elements for exchanging signals or power with the pixel array section and the peripheral circuit area. 
         [0039]    Next, with reference to  FIGS. 1 and 2 , the stacked layer structure of the CMOS image sensor according to this embodiment will be described. 
         [0040]    In the figures, a photoreceptive section  111  of the photodiodes of the multiple pixels is provided in the upper layer part of the silicon substrate  100 . The pixel transistor circuits included in each pixel are omitted in  FIGS. 1 and 2 .  FIG. 10  shows the layout of the photoreceptive section  111  and a transfer transistor  112  of the photodiode, and the transfer transistor  112  is placed at a corner part of the photoreceptive section  111 .  FIG. 10  schematically shows the layout. In reality, the transistor is much smaller than the photoreceptive section and is provided along with other transistors such as the amplifier, select and reset transistors. 
         [0041]    A flattening film (interlayer insulating film)  116  and wiring  110  are provided on the top surface of the silicon substrate  100  through a gate insulating film  100 A and a gate electrode, not shown, for example, and an intralayer lens  109  is provided thereon. The intralayer lens  109  is a convex lens for each of all pixels as in the example in the past ( FIGS. 12 and 13 ). The intralayer lenses  109  and wiring  110  are placed as shown in  FIG. 9 . 
         [0042]    The micro lens  109  is formed by forming a lens material all over a base, patterning a resist into a convex plane shape in accordance with a lens pattern thereon, forming a lens shape by the surface tension generated by thermal fusion reflow and transferring it to the lens material by etching it back. The flattening film  116  is formed from an SiON-based film or a low-refractive-index SiN-based film. The micro lens  109  is formed from a high-refractive-index SiN-based film. 
         [0043]    A flattening film (interlayer insulating film)  115  and wiring  108  are provided thereon, and an intralayer lens  107  is provided thereon. The intralayer lens  107  has a different construction from that of the example in the past ( FIGS. 12 and 13 ) and is a concave lens provided only for a pixel having a blue filter  104 . The intralayer lenses  107  and wiring  108  are laid out as shown in  FIG. 8 . The micro lens  107  is formed by forming a lens material all over a base, patterning a resist thereon into an opening form in accordance with a lens pattern and then forming it on the lens material by performing isotropic etching thereon. The flattening film  115  is formed from an SiON-based film or a low-refractive-index SiN-based film. The micro lens  107  is formed from a high-refractive-index SiN-based film. 
         [0044]    A flattening film (interlayer insulating film)  114  and wiring  106  are provided thereon, and an intralayer lens  105  is provided thereon. The intralayer lens  105  has a different construction from that of the example in the past ( FIGS. 12 and 13 ) and is a convex lens provided only for a pixel having a red filter  102 . The intralayer lenses  105  and wiring  106  are laid out as shown in  FIG. 7 . The flattening film  114  is formed from an SiON-based film or a low-refractive-index SiN-based film. The micro lens  105  is formed from a high-refractive-index SiN-based film. 
         [0045]    Next, an uppermost flattening film  113  is formed thereon, and the color filters  102 ,  103  and  104  corresponding to pixels are placed on the flattening film  113 .  FIG. 1  shows a section where the red filter  102  and the green filter  103  appear.  FIG. 2  shows a section where the green filter  103  and the blue filter  104  appear. The color filters  102 ,  103  and  104  are laid out as shown in  FIG. 6 . 
         [0046]    An on-chip lens  101  is provided on the color filters  102 ,  103  and  104  through a protective film. The on-chip lens  101  corresponds to all pixels as shown in  FIG. 5 . The flattening film  113  is formed from an SiON-based film or a low-refractive-index SiN-based film, and the micro lens  101  is formed from a high-refractive-index SiN-based film. 
         [0047]    The selection of a convex lens or a concave lens as the intralayer lens for each color may depend on the purpose of the optimization. 
         [0048]    As described above, in the image sensor according to this embodiment, the number of lenses and the construction of the lens (including lens curvature and/or convex lens or concave lens) may depend on the construction of color filters for the optimization of light gathering for each color. The different micro lens constructions in relation to colors of color filters can optimize the light gathering states in the photoreceptive sections of the colors, which are caused by differences in wavelength through the color filters. This can reduce an unevenness of color shading caused by different light gathering states for colors at central and peripheral photoreceptive section due to the difference in aperture of a camera lens and incident angle of light at central and peripheral photoreceptive section. 
         [0049]    Having described above that the invention is applied to a CMOS image sensor, the invention is not limited to a CMOS image sensor. The invention is applicable to an image sensor having multiple micro lens layers. The optical filter according to the invention is not limited to the primary-color filters but may include complementary-color filters and infrared filters. 
         [0050]    The solid state imaging device is not limited to the one having an image sensor on one chip but may have a construction in which an imaging section having an image sensor and a signal processing section and an optical system are provided as separate components in a package. Alternatively, the solid state imaging device may be integrated with a control section and/or an operating section and be used for a camera system or a cellular phone. In other words, according to the invention, a single image sensor may refer to a solid state imaging device, and a combination of the solid state imaging device and another functional part (such as a communication module or a display module) may refer to an imaging apparatus. Both solid state imaging device and imaging apparatus are included in the scope of the invention. 
         [0051]    Specific examples of the imaging apparatus applying the invention will be described below. 
         [0052]      FIG. 11  is a block diagram showing a construction example of a camera apparatus having the CMOS image sensor of the embodiment. 
         [0053]    In  FIG. 11 , an imaging section  310  images a subject by using the CMOS image sensor shown in  FIGS. 3 and 4 , for example, and outputs an image signal to a system control section  320  on a main substrate. In other words, the imaging section  310  performs processing such as AGC (automatic gain control), OB (optical black) clamp, CDS (correlated double sampling), and A/D conversion on the output signals from the CMOS image sensor and generates and outputs digital image signals. 
         [0054]    Having described the example in which image signals are converted to digital signals within the imaging section  310  and are output to the system control section  320 , analog image signals may be supplied from the imaging section  310  to the system control section  320  and may be converted to digital signals in the system control section  320 . Various schemes may be applied in the processing within the imaging section  310  and are not limited in particular. 
         [0055]    An imaging optical system  300  includes a zoom lens  301  and an aperture mechanism  302  placed in a lens barrel and forms a subject image in the photoreceptive section of the CMOS image sensor. Under the control of a drive/control section  330  based on an instruction from the system control section  320 , the corresponding section or sections are driven mechanically to perform control such as auto focus. 
         [0056]    The system control section  320  includes a CPU  321 , a ROM  322 , a RAM  323 , a DSP  324  and an external interface  325 . 
         [0057]    The CPU  321  transmits an instruction to a component of the camera apparatus through the ROM  322  and RAM  323  to control the entire system. 
         [0058]    The DSP  324  performs signal processing on image signals from the imaging section  310  to generate video signals (such as YUV signals) of a still picture or a moving picture in a predetermined format. 
         [0059]    The external interface  325  includes an encoder and a D/A converter and exchanges a control signal or data with an external element (that is, a display  360 , a memory medium  340  and a control panel section  350  in this example) connecting to the system control section  320 . 
         [0060]    The display  360  is a small display such as a liquid crystal panel built in the camera apparatus and displays an imaged image. In addition to the small display built in a camera apparatus, a construction is apparently applicable in which image data is transmitted to an external large display apparatus to display. 
         [0061]    A shot image may be saved in the memory medium  340  such as a memory card, and the memory medium is replaceable for the memory medium controller  341 . The memory medium  340  may be a magnetic or optical disk medium instead of a memory card. 
         [0062]    The control panel section  350  includes an input key for instructing by a user when a shooting operation is performed in the camera apparatus. The CPU  321  monitors an input signal from the control panel section  350  and performs operational control based on the contents of the input. 
         [0063]    By applying the invention to the camera apparatus, high quality shooting can be performed on various subjects. In this construction, the combination of unit devices or/and unit modules to be included in the system, and the size of the set may be selected properly based on the actual situation of the commercialization. The imaging apparatus of the invention widely includes various changes. 
         [0064]    In the solid state imaging device and imaging apparatus of the invention, the subject to be imaged is not limited to a person and/or scenery in a general video image. The solid state imaging device and imaging apparatus of the invention are also applicable to the imaging of a special fine image pattern as in a counterfeit bill detector or a fingerprint detector, for example. In this case, instead of the general camera apparatus shown in  FIG. 11 , the apparatus construction further includes a special imaging optical system and a signal processing system including pattern analysis. Also in this case, the operational effect of the invention may be fully used to implement precise image detection. 
         [0065]    In a remote system for remote medical care, crime prevention monitoring or personal authentication, for example, the apparatus construction may include a communication module connecting to a network as described above, and wide variety of applications can be achieved. 
         [0066]    It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.