US20080265297A1 - CMOS image sensor and method for manufacturing the same - Google Patents

CMOS image sensor and method for manufacturing the same Download PDF

Info

Publication number
US20080265297A1
US20080265297A1 US12/216,373 US21637308A US2008265297A1 US 20080265297 A1 US20080265297 A1 US 20080265297A1 US 21637308 A US21637308 A US 21637308A US 2008265297 A1 US2008265297 A1 US 2008265297A1
Authority
US
United States
Prior art keywords
epitaxial layer
image sensor
photodiode region
type
blue photodiode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US12/216,373
Inventor
Chang Hun Han
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
DB HiTek Co Ltd
Original Assignee
Dongbu Electronics Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Dongbu Electronics Co Ltd filed Critical Dongbu Electronics Co Ltd
Priority to US12/216,373 priority Critical patent/US20080265297A1/en
Assigned to DONGBU ELECTRONICS CO., LTD. reassignment DONGBU ELECTRONICS CO., LTD. CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: DONGBUANAM SEMICONDUCTOR INC.
Publication of US20080265297A1 publication Critical patent/US20080265297A1/en
Abandoned legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14683—Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof
    • H01L27/14689—MOS based technologies
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14643—Photodiode arrays; MOS imagers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
    • H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by at least one potential-jump barrier or surface barrier, e.g. phototransistors

Definitions

  • the present invention relates to complementary metal-oxide-semiconductor (CMOS) image sensors, and more particularly, to a blue photodiode of a CMOS image sensor and a method for manufacturing the same, in which the blue photodiode is formed to be higher and wider than a semiconductor substrate to improve sensitivity of blue light.
  • CMOS complementary metal-oxide-semiconductor
  • An image sensor is a semiconductor device that converts optical images to electrical signals.
  • the image sensor is classified into a charge-coupled device (CCD) and a CMOS image sensor.
  • the CCD stores charge carriers in MOS capacitors and transfers the charge carriers to the MOS capacitors.
  • the MOS capacitors are approximate to one another.
  • the CMOS image sensor employs a switching mode that sequentially detects outputs of unit pixels using MOS transistors by forming the MOS transistors to correspond to the number of the unit pixels using CMOS technology that uses a control circuit and a signal processing circuit as peripheral circuits.
  • the CMOS image sensor that converts data of an object into electrical signals includes signal processing chips having photodiodes.
  • Each of the signal processing chips includes an amplifier, an analog-to-digital converter, an internal voltage generator, a timing generator, and a digital logic.
  • the CMOS image sensor is economical in view of space, power consumption, and cost.
  • the manufacture of the CCD requires technical process steps.
  • a CMOS image sensor can be manufactured in mass production by a simple etching process of a silicon wafer. Thus, it is cheaper to manufacture a CMOS image sensor than to manufacture the CCD.
  • an advantage of the CMOS image sensor is its packing density.
  • the CMOS image sensor sequentially detects signals in a switching mode by forming a photodiode and a transistor in a unit pixel. Also, since the CMOS image sensor uses CMOS technology, low power consumption is required. The number of masks for a CMOS image sensor is fewer by twenty fewer than the thirty to forty masks required for the CCD image sensor. In this way, in the CMOS image sensor, process steps are simplified and various signal processing circuits can be integrated in one chip. Therefore, the CMOS image sensor has received much attention as an image sensor for the next generation.
  • FIGS. 1 and 2 show a unit circuit of a related art CMOS image sensor.
  • a photodiode PD for generating optical charges using received light
  • a transfer transistor 101 for transferring the optical charges generated by the photodiode to a floating diffusion region 102 by applying a signal Tx to its gate
  • a reset transistor 103 for resetting the floating diffusion region 102 by applying a signal Rx to its gate to set the potential of the floating diffusion region 102 at a desired value and for discharging the floating diffusion region 102
  • a drive transistor 104 serving as a source-follower buffer amplifier by applying a signal Dx to its gate
  • a selection transistor 105 for addressing and applying a signal Sx to its gate
  • a load transistor 106 for providing an output signal (V b ) to be read out from the unit pixel. Power (V DD ) is applied.
  • a P-type epitaxial layer 111 is grown on a heavily doped P-type substrate 110 , and a lightly doped N-type photodiode region 113 , a P-type well 114 and a device isolation film (FOX) 112 are formed in the epitaxial layer 111 .
  • the transfer transistor 101 and the reset transistor 103 are formed on the epitaxial layer 111 between the photodiode region 113 and the P-type well 114 .
  • the drive transistor 104 and the selection transistor 105 are formed on the P-type well 114 .
  • the floating diffusion region 102 is formed on the epitaxial layer 111 between the transfer transistor 101 and the reset transistor 103 .
  • a P-type diffusion layer 115 is formed in the lightly doped N-type photodiode region 113 below the surface of the lightly doped P-type epitaxial layer 111 and is doped more lightly than the epitaxial layer.
  • the device isolation film 112 is formed on the semiconductor substrate 110 in which the lightly doped P-type epitaxial layer 111 is formed.
  • the device isolation film 112 serves to isolate an active region including the lightly doped N-type photodiode region 113 .
  • the transfer transistor 101 including a gate electrode is formed on the epitaxial layer 111 .
  • a first interlayer dielectric film 116 is formed on the epitaxial layer 111 including the transfer transistor 101 .
  • the first interlayer dielectric film 116 is selectively etched to form a via hole 117 .
  • a first metal layer (not shown) is deposited and selectively etched to form a first metal layer pattern 118 .
  • a second interlayer dielectric film 119 is formed on the first interlayer dielectric film 116 including the first metal layer pattern 118 .
  • a second metal layer (not shown) is formed on the second interlayer dielectric film 119 and then selectively etched to form a second metal layer pattern 120 .
  • a third interlayer dielectric film 121 including the second metal layer pattern 120 is formed on the second interlayer dielectric film 119 .
  • a device passivation layer 122 is formed on the third interlayer dielectric film 121 .
  • a blue color filter array element 123 is formed on the device passivation layer 122 as part of a color filter array.
  • the color filter array includes a red filter pattern, a blue filter pattern, and a green filter pattern.
  • a planarization layer 124 is formed on the blue color filter array element 123 .
  • a microlens 125 is formed on the planarization layer 124 and corresponds to the blue color filter array element 123 .
  • the blue photodiode may fail to sense shorter wavelengths because blue light in a general pixel structure has a penetration depth of 0.3 ⁇ m.
  • red light has a penetration depth of 10 ⁇ m. Therefore, the desired display of the respective colors (i.e., red, green, and blue) at a ratio of 1:1 is impeded, thereby degrading color reproduction quality.
  • the present invention is directed to a blue photodiode of a CMOS image sensor and a method for manufacturing the same that substantially obviates one or more problems due to limitations and disadvantages of the related art.
  • An advantage of the present invention is to provide a blue photodiode of a CMOS image sensor and a method for manufacturing the same, in which the blue photodiode is imparted with a greater thickness, to improve sensitivity of blue light.
  • a CMOS image sensor comprising a semiconductor substrate; a gate electrode formed on the semiconductor substrate; a first blue photodiode region formed in the semiconductor substrate; and a second blue photodiode region formed on the first blue photodiode region.
  • a CMOS image sensor comprising a first lightly doped P-type epitaxial layer formed on a heavily doped P-type semiconductor substrate; a gate electrode of a transfer transistor formed on the first epitaxial layer; a first N-type blue photodiode region formed on the first epitaxial layer; and a second N-type blue photodiode region formed on the first epitaxial layer corresponding to the first blue photodiode region.
  • a method for manufacturing a CMOS image sensor comprising forming a gate electrode on a semiconductor substrate; forming a first blue photodiode region in the semiconductor substrate; and forming a second blue photodiode region on the first blue photodiode region.
  • a method for manufacturing a CMOS image sensor comprising forming a first lightly doped P-type epitaxial layer on a heavily doped P-type semiconductor substrate; forming a gate electrode on the first epitaxial layer; forming a first N-type blue photodiode region on the first epitaxial layer; forming a second N-type epitaxial layer on the first epitaxial layer including the first blue photodiode region; and forming a second N-type blue photodiode region by patterning the second epitaxial layer to remain only on the first blue photodiode region.
  • a method for manufacturing a CMOS image sensor comprising forming a first lightly doped P-type epitaxial layer on a heavily doped P-type semiconductor substrate; forming a gate electrode on the first epitaxial layer; forming a first N-type blue photodiode region on the first epitaxial layer; forming a dielectric film on the first epitaxial layer including the first blue photodiode region; patterning the dielectric film to expose the first blue photodiode region; and forming a second blue photodiode region by forming a second N-type epitaxial layer on the first epitaxial layer corresponding to the first blue photodiode region.
  • the second blue photodiode region has a thickness of 300 ⁇ to 5000 ⁇ .
  • FIG. 1 is a plan view of a unit circuit of a related art CMOS image sensor
  • FIG. 2 is a sectional view of the CMOS image sensor shown in FIG. 1 ;
  • FIG. 3 is a sectional view of a blue photodiode portion of a CMOS image sensor according to a related art
  • FIG. 4 is a sectional view of a blue photodiode portion of a CMOS image sensor according to the present invention.
  • FIGS. 5-9 are sectional views of a blue photodiode of a CMOS image sensor fabricated according to an embodiment of the method of the present invention.
  • FIGS. 10-13 are sectional views of a blue photodiode of a CMOS image sensor fabricated according to another embodiment of the method of the present invention.
  • a device isolation film 212 is formed on a semiconductor substrate 210 in which a first lightly doped P-type epitaxial layer 211 is formed.
  • the device isolation film 212 serves to isolate an active region including a lightly doped N-type blue photodiode region 213 .
  • a second lightly doped N-type epitaxial layer 226 is formed on the photodiode region 213 .
  • a transfer transistor 201 including a gate electrode is formed on the first epitaxial layer 211 .
  • a first interlayer dielectric film 216 is formed on the first epitaxial layer 211 including the transfer transistor 201 .
  • the first interlayer dielectric film 216 is selectively etched to form a via hole 217 .
  • a first metal layer (not shown) is deposited and selectively etched to form a first metal layer pattern 218 .
  • a second interlayer dielectric film 219 is formed on the first interlayer dielectric film 216 including the first metal layer pattern 218 .
  • a second metal layer (not shown) is formed on the second interlayer dielectric film 219 and then selectively etched to form a second metal layer pattern 220 .
  • a third interlayer dielectric film 221 including the second metal layer pattern 220 is formed on the second interlayer dielectric film 219 .
  • a device passivation layer 222 is formed on the third interlayer dielectric film 221 .
  • a blue color filter array element 223 is formed on the device passivation layer 222 as part of a color filter array.
  • the color filter array includes a red filter pattern, a blue filter pattern, and a green filter pattern.
  • a planarization layer 224 is formed on the blue color filter array element 223 .
  • a microlens 225 is formed on the planarization layer 224 to correspond to the blue color filter array element 223 .
  • FIGS. 5-9 respectively illustrate sequential process steps of a method for fabricating a CMOS image sensor according to an embodiment of the present invention.
  • the device isolation film 212 is formed in the semiconductor substrate (not shown) on which the first lightly doped P-type epitaxial layer 211 is formed.
  • the device isolation film 212 serves to isolate devices from each other.
  • the transfer transistor 201 including a gate electrode and the lightly doped N-type blue photodiode region 213 are formed in the first epitaxial layer 211 .
  • the second lightly doped N-type epitaxial layer 226 is grown to a thickness of 300 ⁇ to 5000 ⁇ on the first epitaxial layer 211 including the blue photodiode region 213 . There is no growth of the second epitaxial layer 226 on the transfer transistor 201 .
  • a photoresist film pattern 227 is formed on the second epitaxial layer 226 corresponding to the blue photodiode region 213 .
  • the second epitaxial layer 226 is etched using the photoresist film pattern 227 as a mask such that the second epitaxial layer 226 remains only on the first epitaxial layer 211 corresponding to the blue photodiode region 213 .
  • the photoresist film pattern 227 is removed.
  • FIGS. 10-13 respectively illustrate sequential process steps of a method for fabricating a CMOS image sensor according to another embodiment of the present invention.
  • the device isolation film 212 is formed in the semiconductor substrate (not shown) in which the first lightly doped P-type epitaxial layer 211 is formed.
  • the device isolation film 212 serves to isolate devices from each other.
  • the transfer transistor 201 including a gate electrode and the lightly doped N-type blue photodiode region 213 are formed on the first epitaxial layer 211 .
  • An interlayer dielectric film 230 is formed on the first epitaxial layer 211 including the transfer transistor 201 .
  • a photoresist film pattern 231 that exposes an upper region corresponding to the blue photodiode region 213 is formed by depositing a photoresist layer on the interlayer dielectric film 230 and patterning the deposited photoresist layer by photolithography including exposure and development steps.
  • the interlayer dielectric film 230 is etched using the photoresist film pattern 231 as a mask, to thereby remove the exposed portion.
  • a second lightly doped N-type epitaxial layer 226 is grown. There is no growth of the second epitaxial layer 226 where the interlayer dielectric film 230 is formed.
  • CMOS image sensor manufactured above, sensitivity of blue light is improved, and the overall thickness of the effective blue photodiode region is increased by using a portion above the device isolation film as an area or depth sensitive to blue light. Since the lightly doped N-type epitaxial layer that receives the blue light is imparted with a greater thickness, which extends above the surface of the semiconductor substrate, the depth of a focus can be reduced to more effectively collect the light and thereby improve color reproduction characteristics.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Electromagnetism (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Solid State Image Pick-Up Elements (AREA)
  • Transforming Light Signals Into Electric Signals (AREA)

Abstract

A CMOS image sensor and a method for manufacturing the same are disclosed, in which a blue photodiode is imparted with a greater thickness to improve sensitivity of blue light. The blue photodiode of a CMOS image sensor includes a first lightly doped P-type epitaxial layer formed on a heavily doped P-type semiconductor substrate; a gate electrode of a transfer transistor formed on the first epitaxial layer; a first N-type blue photodiode region formed on the first epitaxial layer; and a second N-type blue photodiode region formed on the first epitaxial layer corresponding to the first blue photodiode region.

Description

  • This application claims the benefit of Korean Patent Application No. 10-2004-0116423, filed on Dec. 30, 2004, which is hereby incorporated by reference for all purposes as if fully set forth herein.
    • BACKGROUND OF THE INVENTION
  • 1. Field of the Invention
  • The present invention relates to complementary metal-oxide-semiconductor (CMOS) image sensors, and more particularly, to a blue photodiode of a CMOS image sensor and a method for manufacturing the same, in which the blue photodiode is formed to be higher and wider than a semiconductor substrate to improve sensitivity of blue light.
  • 2. Discussion of the Related Art
  • An image sensor is a semiconductor device that converts optical images to electrical signals. The image sensor is classified into a charge-coupled device (CCD) and a CMOS image sensor. The CCD stores charge carriers in MOS capacitors and transfers the charge carriers to the MOS capacitors. The MOS capacitors are approximate to one another. The CMOS image sensor employs a switching mode that sequentially detects outputs of unit pixels using MOS transistors by forming the MOS transistors to correspond to the number of the unit pixels using CMOS technology that uses a control circuit and a signal processing circuit as peripheral circuits.
  • The CMOS image sensor that converts data of an object into electrical signals includes signal processing chips having photodiodes. Each of the signal processing chips includes an amplifier, an analog-to-digital converter, an internal voltage generator, a timing generator, and a digital logic. The CMOS image sensor is economical in view of space, power consumption, and cost. The manufacture of the CCD requires technical process steps. However, a CMOS image sensor can be manufactured in mass production by a simple etching process of a silicon wafer. Thus, it is cheaper to manufacture a CMOS image sensor than to manufacture the CCD. Also, an advantage of the CMOS image sensor is its packing density.
  • To display images, the CMOS image sensor sequentially detects signals in a switching mode by forming a photodiode and a transistor in a unit pixel. Also, since the CMOS image sensor uses CMOS technology, low power consumption is required. The number of masks for a CMOS image sensor is fewer by twenty fewer than the thirty to forty masks required for the CCD image sensor. In this way, in the CMOS image sensor, process steps are simplified and various signal processing circuits can be integrated in one chip. Therefore, the CMOS image sensor has received much attention as an image sensor for the next generation.
  • FIGS. 1 and 2 show a unit circuit of a related art CMOS image sensor.
  • As shown in FIG. 1, a photodiode PD for generating optical charges using received light, a transfer transistor 101 for transferring the optical charges generated by the photodiode to a floating diffusion region 102 by applying a signal Tx to its gate, a reset transistor 103 for resetting the floating diffusion region 102 by applying a signal Rx to its gate to set the potential of the floating diffusion region 102 at a desired value and for discharging the floating diffusion region 102, a drive transistor 104 serving as a source-follower buffer amplifier by applying a signal Dx to its gate, a selection transistor 105 for addressing and applying a signal Sx to its gate, and a load transistor 106 for providing an output signal (Vb) to be read out from the unit pixel. Power (VDD) is applied.
  • As shown in FIG. 2, a P-type epitaxial layer 111 is grown on a heavily doped P-type substrate 110, and a lightly doped N-type photodiode region 113, a P-type well 114 and a device isolation film (FOX) 112 are formed in the epitaxial layer 111. The transfer transistor 101 and the reset transistor 103 are formed on the epitaxial layer 111 between the photodiode region 113 and the P-type well 114. The drive transistor 104 and the selection transistor 105 are formed on the P-type well 114. The floating diffusion region 102 is formed on the epitaxial layer 111 between the transfer transistor 101 and the reset transistor 103. A P-type diffusion layer 115 is formed in the lightly doped N-type photodiode region 113 below the surface of the lightly doped P-type epitaxial layer 111 and is doped more lightly than the epitaxial layer.
  • Referring to FIG. 3, illustrating a blue photodiode portion of the above CMOS image sensor, the device isolation film 112 is formed on the semiconductor substrate 110 in which the lightly doped P-type epitaxial layer 111 is formed. The device isolation film 112 serves to isolate an active region including the lightly doped N-type photodiode region 113. The transfer transistor 101 including a gate electrode is formed on the epitaxial layer 111. A first interlayer dielectric film 116 is formed on the epitaxial layer 111 including the transfer transistor 101. The first interlayer dielectric film 116 is selectively etched to form a via hole 117. Then, a first metal layer (not shown) is deposited and selectively etched to form a first metal layer pattern 118. A second interlayer dielectric film 119 is formed on the first interlayer dielectric film 116 including the first metal layer pattern 118. A second metal layer (not shown) is formed on the second interlayer dielectric film 119 and then selectively etched to form a second metal layer pattern 120. A third interlayer dielectric film 121 including the second metal layer pattern 120 is formed on the second interlayer dielectric film 119. A device passivation layer 122 is formed on the third interlayer dielectric film 121. A blue color filter array element 123 is formed on the device passivation layer 122 as part of a color filter array. The color filter array includes a red filter pattern, a blue filter pattern, and a green filter pattern. A planarization layer 124 is formed on the blue color filter array element 123. Finally, a microlens 125 is formed on the planarization layer 124 and corresponds to the blue color filter array element 123.
  • In the related art CMOS image sensor manufactured above, however, the blue photodiode may fail to sense shorter wavelengths because blue light in a general pixel structure has a penetration depth of 0.3 μm. By contrast, red light has a penetration depth of 10 μm. Therefore, the desired display of the respective colors (i.e., red, green, and blue) at a ratio of 1:1 is impeded, thereby degrading color reproduction quality.
    • SUMMARY OF THE INVENTION
  • Accordingly, the present invention is directed to a blue photodiode of a CMOS image sensor and a method for manufacturing the same that substantially obviates one or more problems due to limitations and disadvantages of the related art.
  • An advantage of the present invention is to provide a blue photodiode of a CMOS image sensor and a method for manufacturing the same, in which the blue photodiode is imparted with a greater thickness, to improve sensitivity of blue light.
  • Additional features and advantages of the invention will be set forth in the description which follows, and in part will be, apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure and method particularly pointed out in the written description and claims hereof as well as the appended drawings.
  • To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided a CMOS image sensor comprising a semiconductor substrate; a gate electrode formed on the semiconductor substrate; a first blue photodiode region formed in the semiconductor substrate; and a second blue photodiode region formed on the first blue photodiode region.
  • In another aspect of the present invention, there is provided a CMOS image sensor comprising a first lightly doped P-type epitaxial layer formed on a heavily doped P-type semiconductor substrate; a gate electrode of a transfer transistor formed on the first epitaxial layer; a first N-type blue photodiode region formed on the first epitaxial layer; and a second N-type blue photodiode region formed on the first epitaxial layer corresponding to the first blue photodiode region.
  • In another aspect of the present invention, there is provided a method for manufacturing a CMOS image sensor comprising forming a gate electrode on a semiconductor substrate; forming a first blue photodiode region in the semiconductor substrate; and forming a second blue photodiode region on the first blue photodiode region.
  • In another aspect of the present invention, there is provided a method for manufacturing a CMOS image sensor comprising forming a first lightly doped P-type epitaxial layer on a heavily doped P-type semiconductor substrate; forming a gate electrode on the first epitaxial layer; forming a first N-type blue photodiode region on the first epitaxial layer; forming a second N-type epitaxial layer on the first epitaxial layer including the first blue photodiode region; and forming a second N-type blue photodiode region by patterning the second epitaxial layer to remain only on the first blue photodiode region.
  • In another aspect of the present invention, there is provided a method for manufacturing a CMOS image sensor comprising forming a first lightly doped P-type epitaxial layer on a heavily doped P-type semiconductor substrate; forming a gate electrode on the first epitaxial layer; forming a first N-type blue photodiode region on the first epitaxial layer; forming a dielectric film on the first epitaxial layer including the first blue photodiode region; patterning the dielectric film to expose the first blue photodiode region; and forming a second blue photodiode region by forming a second N-type epitaxial layer on the first epitaxial layer corresponding to the first blue photodiode region.
  • According to the present invention, the second blue photodiode region has a thickness of 300 Å to 5000 Å.
  • It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
    • BRIEF DESCRIPTION OF THE DRAWINGS
  • The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:
  • FIG. 1 is a plan view of a unit circuit of a related art CMOS image sensor;
  • FIG. 2 is a sectional view of the CMOS image sensor shown in FIG. 1;
  • FIG. 3 is a sectional view of a blue photodiode portion of a CMOS image sensor according to a related art;
  • FIG. 4 is a sectional view of a blue photodiode portion of a CMOS image sensor according to the present invention;
  • FIGS. 5-9 are sectional views of a blue photodiode of a CMOS image sensor fabricated according to an embodiment of the method of the present invention; and
  • FIGS. 10-13 are sectional views of a blue photodiode of a CMOS image sensor fabricated according to another embodiment of the method of the present invention.
    •  DETAILED DESCRIPTION OF THE INVENTION
  • Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, like reference designations will be used throughout the drawings to refer to the same or similar parts.
  • Referring to FIG. 4, illustrating a blue photodiode portion of a CMOS image sensor according to the present invention, a device isolation film 212 is formed on a semiconductor substrate 210 in which a first lightly doped P-type epitaxial layer 211 is formed. The device isolation film 212 serves to isolate an active region including a lightly doped N-type blue photodiode region 213. A second lightly doped N-type epitaxial layer 226 is formed on the photodiode region 213.
  • A transfer transistor 201 including a gate electrode is formed on the first epitaxial layer 211. A first interlayer dielectric film 216 is formed on the first epitaxial layer 211 including the transfer transistor 201. The first interlayer dielectric film 216 is selectively etched to form a via hole 217. Then, a first metal layer (not shown) is deposited and selectively etched to form a first metal layer pattern 218. A second interlayer dielectric film 219 is formed on the first interlayer dielectric film 216 including the first metal layer pattern 218. A second metal layer (not shown) is formed on the second interlayer dielectric film 219 and then selectively etched to form a second metal layer pattern 220. A third interlayer dielectric film 221 including the second metal layer pattern 220 is formed on the second interlayer dielectric film 219. A device passivation layer 222 is formed on the third interlayer dielectric film 221. A blue color filter array element 223 is formed on the device passivation layer 222 as part of a color filter array. The color filter array includes a red filter pattern, a blue filter pattern, and a green filter pattern. A planarization layer 224 is formed on the blue color filter array element 223. Finally, a microlens 225 is formed on the planarization layer 224 to correspond to the blue color filter array element 223.
  • FIGS. 5-9 respectively illustrate sequential process steps of a method for fabricating a CMOS image sensor according to an embodiment of the present invention.
  • As shown in FIG. 5, the device isolation film 212 is formed in the semiconductor substrate (not shown) on which the first lightly doped P-type epitaxial layer 211 is formed. The device isolation film 212 serves to isolate devices from each other. The transfer transistor 201 including a gate electrode and the lightly doped N-type blue photodiode region 213 are formed in the first epitaxial layer 211.
  • As shown in FIG. 6, the second lightly doped N-type epitaxial layer 226 is grown to a thickness of 300 Å to 5000 Å on the first epitaxial layer 211 including the blue photodiode region 213. There is no growth of the second epitaxial layer 226 on the transfer transistor 201.
  • As shown in FIG. 7, a photoresist film pattern 227 is formed on the second epitaxial layer 226 corresponding to the blue photodiode region 213. As shown in FIG. 8, the second epitaxial layer 226 is etched using the photoresist film pattern 227 as a mask such that the second epitaxial layer 226 remains only on the first epitaxial layer 211 corresponding to the blue photodiode region 213. As shown in FIG. 9, the photoresist film pattern 227 is removed.
  • FIGS. 10-13 respectively illustrate sequential process steps of a method for fabricating a CMOS image sensor according to another embodiment of the present invention.
  • As shown in FIG. 10, the device isolation film 212 is formed in the semiconductor substrate (not shown) in which the first lightly doped P-type epitaxial layer 211 is formed. The device isolation film 212 serves to isolate devices from each other. The transfer transistor 201, including a gate electrode and the lightly doped N-type blue photodiode region 213 are formed on the first epitaxial layer 211. An interlayer dielectric film 230 is formed on the first epitaxial layer 211 including the transfer transistor 201.
  • As shown in FIG. 11, a photoresist film pattern 231 that exposes an upper region corresponding to the blue photodiode region 213 is formed by depositing a photoresist layer on the interlayer dielectric film 230 and patterning the deposited photoresist layer by photolithography including exposure and development steps.
  • As shown in FIG. 12, the interlayer dielectric film 230 is etched using the photoresist film pattern 231 as a mask, to thereby remove the exposed portion.
  • As shown in FIG. 13, a second lightly doped N-type epitaxial layer 226 is grown. There is no growth of the second epitaxial layer 226 where the interlayer dielectric film 230 is formed.
  • In the CMOS image sensor manufactured above, sensitivity of blue light is improved, and the overall thickness of the effective blue photodiode region is increased by using a portion above the device isolation film as an area or depth sensitive to blue light. Since the lightly doped N-type epitaxial layer that receives the blue light is imparted with a greater thickness, which extends above the surface of the semiconductor substrate, the depth of a focus can be reduced to more effectively collect the light and thereby improve color reproduction characteristics.
  • It will be apparent to those skilled in the art that various modifications and variation can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of the invention provided they come within the scope of the appended claims and their equivalents.

Claims (7)

1. A CMOS image sensor, comprising:
a semiconductor substrate;
a gate electrode formed on the semiconductor substrate;
a first blue photodiode region formed in the semiconductor substrate; and
a second blue photodiode region formed on the first blue photodiode region.
2. A CMOS image sensor, comprising:
a first lightly doped P-type epitaxial layer formed on a heavily doped P-type semiconductor substrate;
a gate electrode of a transfer transistor formed on the first epitaxial layer;
a first N-type blue photodiode region formed on the first epitaxial layer; and
a second N-type blue photodiode region formed on the first epitaxial layer corresponding to the first blue photodiode region.
3-8. (canceled)
9. The sensor as claimed in claim 1, wherein a thickness of the second blue photodiode region is 300 Å to 5000 Å.
10. The sensor as claimed in claim 2, wherein a thickness of the second N-type blue photodiode region is 300 Å to 5000 Å.
11. The sensor as claimed in claim 2, further comprising:
a second N-type epitaxial layer formed on the first lightly doped P-type epitaxial layer including the first N-type blue photodiode region.
12. The sensor as claimed in claim 2, further comprising:
a dielectric formed on the first epitaxial layer including the first blue photodiode region.
US12/216,373 2004-12-30 2008-07-02 CMOS image sensor and method for manufacturing the same Abandoned US20080265297A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US12/216,373 US20080265297A1 (en) 2004-12-30 2008-07-02 CMOS image sensor and method for manufacturing the same

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
KR1020040116423A KR100672675B1 (en) 2004-12-30 2004-12-30 Method for manufacturing of Blue photo diode in CMOS image sensor
KR10-2004-0116423 2004-12-30
US11/319,586 US7405097B2 (en) 2004-12-30 2005-12-29 CMOS image sensor and method for manufacturing the same
US12/216,373 US20080265297A1 (en) 2004-12-30 2008-07-02 CMOS image sensor and method for manufacturing the same

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
US11/319,586 Division US7405097B2 (en) 2004-12-30 2005-12-29 CMOS image sensor and method for manufacturing the same

Publications (1)

Publication Number Publication Date
US20080265297A1 true US20080265297A1 (en) 2008-10-30

Family

ID=36639395

Family Applications (2)

Application Number Title Priority Date Filing Date
US11/319,586 Expired - Fee Related US7405097B2 (en) 2004-12-30 2005-12-29 CMOS image sensor and method for manufacturing the same
US12/216,373 Abandoned US20080265297A1 (en) 2004-12-30 2008-07-02 CMOS image sensor and method for manufacturing the same

Family Applications Before (1)

Application Number Title Priority Date Filing Date
US11/319,586 Expired - Fee Related US7405097B2 (en) 2004-12-30 2005-12-29 CMOS image sensor and method for manufacturing the same

Country Status (3)

Country Link
US (2) US7405097B2 (en)
KR (1) KR100672675B1 (en)
CN (1) CN100527427C (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130175653A1 (en) * 2012-01-05 2013-07-11 Taiwan Semiconductor Manufacturing Company, Ltd. Sensing product and method of making

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100776153B1 (en) * 2006-08-28 2007-11-16 동부일렉트로닉스 주식회사 Cmos image sensor and the method of fabricating thereof
CN117038686B (en) * 2023-07-28 2024-04-16 中山大学 Pixel structure, photodiode and CMOS image sensor

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6489643B1 (en) * 1998-06-27 2002-12-03 Hynix Semiconductor Inc. Photodiode having a plurality of PN junctions and image sensor having the same
US7226803B2 (en) * 2003-06-16 2007-06-05 Micron Technology, Inc. Photodiode with ultra-shallow junction for high quantum efficiency CMOS image sensor and method of formation

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62269355A (en) 1986-05-16 1987-11-21 Mitsubishi Electric Corp Solid-state image sensing element
KR100365744B1 (en) 2000-12-11 2002-12-27 주식회사 하이닉스반도체 Photodiode in image sensor and method for fabricating the same

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6489643B1 (en) * 1998-06-27 2002-12-03 Hynix Semiconductor Inc. Photodiode having a plurality of PN junctions and image sensor having the same
US7226803B2 (en) * 2003-06-16 2007-06-05 Micron Technology, Inc. Photodiode with ultra-shallow junction for high quantum efficiency CMOS image sensor and method of formation

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130175653A1 (en) * 2012-01-05 2013-07-11 Taiwan Semiconductor Manufacturing Company, Ltd. Sensing product and method of making
US9419155B2 (en) * 2012-01-05 2016-08-16 Taiwan Semiconductor Manufacturing Company, Ltd. Sensing product and method of making

Also Published As

Publication number Publication date
CN1819233A (en) 2006-08-16
US20060145214A1 (en) 2006-07-06
KR20060077533A (en) 2006-07-05
CN100527427C (en) 2009-08-12
US7405097B2 (en) 2008-07-29
KR100672675B1 (en) 2007-01-24

Similar Documents

Publication Publication Date Title
US7232698B2 (en) Method for fabricating CMOS image sensor protecting low temperature oxide delamination
JP4224036B2 (en) Image sensor with embedded photodiode region and method of manufacturing the same
KR101550067B1 (en) Image sensor and method of manufacturing the same
US20160064437A1 (en) Solid-state imaging device and method of manufacturing the same, and imaging apparatus
US7973342B2 (en) CMOS image sensor and method for manufacturing the same
JP2011204992A (en) Solid-state image sensor and method of manufacturing the same, and electronic apparatus
KR100832721B1 (en) Method for fabricaing cmos image sensor
KR100698097B1 (en) CMOS image sensor and method for manufacturing the same
US20060138494A1 (en) Photodiode in CMOS image sensor and fabricating method thereof
US7678602B2 (en) CMOS image sensor and method for manufacturing the same
KR100801850B1 (en) Image sensor and method of manufacturing the same
US7405097B2 (en) CMOS image sensor and method for manufacturing the same
KR100672671B1 (en) CMOS image sensor and method for manufacturing the same
US7732245B2 (en) Photodiode of CMOS image sensor and method for manufacturing the same
US20070246757A1 (en) CMOS image sensor and method for fabricating the same
JP4967291B2 (en) Method for manufacturing solid-state imaging device
US20060138490A1 (en) CMOS image sensor and method for fabricating the same
US20060145175A1 (en) CMOS image sensor and method for fabricating the same
US20070080413A1 (en) CMOS image sensor and method for manufacturing the same
US7344911B2 (en) CMOS image sensor and method for fabricating the same
KR100672710B1 (en) CMOS image sensor and method of manufacturing the same
KR100672693B1 (en) Method for fabricating an COMS image sensor
KR20060044088A (en) Pixel circuit in the solid-state image-sensing device having a transfer gate of trench structure
KR100606907B1 (en) Method For Fabricating CMOS Image Sensor
KR100935764B1 (en) Image sensor and method for fabricating the same

Legal Events

Date Code Title Description
AS Assignment

Owner name: DONGBU ELECTRONICS CO., LTD., KOREA, REPUBLIC OF

Free format text: CHANGE OF NAME;ASSIGNOR:DONGBUANAM SEMICONDUCTOR INC.;REEL/FRAME:021256/0342

Effective date: 20060324

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION