KR20100044994A - An image sensor and method for manufacturing an image sensor - Google Patents

An image sensor and method for manufacturing an image sensor Download PDF

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Publication number
KR20100044994A
KR20100044994A KR1020080104004A KR20080104004A KR20100044994A KR 20100044994 A KR20100044994 A KR 20100044994A KR 1020080104004 A KR1020080104004 A KR 1020080104004A KR 20080104004 A KR20080104004 A KR 20080104004A KR 20100044994 A KR20100044994 A KR 20100044994A
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South Korea
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forming
epitaxial layer
photodiode
silicon
silicon epitaxial
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KR1020080104004A
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Korean (ko)
Inventor
이동환
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주식회사 동부하이텍
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Priority to KR1020080104004A priority Critical patent/KR20100044994A/en
Publication of KR20100044994A publication Critical patent/KR20100044994A/en

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    • 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
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14603—Special geometry or disposition of pixel-elements, address-lines or gate-electrodes
    • H01L27/14607—Geometry of the photosensitive area
    • 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
    • H01L27/14601—Structural or functional details thereof
    • H01L27/1462—Coatings
    • 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
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14636—Interconnect 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
    • H01L27/14643—Photodiode arrays; MOS imagers
    • H01L27/14645—Colour imagers
    • H01L27/14647—Multicolour imagers having a stacked pixel-element structure, e.g. npn, npnpn or MQW elements
    • 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
    • H01L27/14685—Process for coatings or optical elements
    • 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
    • H01L27/14683—Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof
    • H01L27/14692—Thin film technologies, e.g. amorphous, poly, micro- or nanocrystalline silicon

Abstract

An image sensor according to an embodiment of the present invention, a semiconductor substrate on which a red photodiode is formed; A first silicon epitaxial layer formed on the semiconductor substrate and including a green photodiode; A second silicon epitaxial layer formed on the first silicon epitaxial layer and having a blue photodiode; A first plug connected to one side of the green photodiode and penetrating the second silicon epi layer; A second plug connected to one side of the red photodiode and penetrating the first silicon epitaxial layer and the second silicon epitaxial layer; And an oxide film formed on the second silicon epi layer at a position corresponding to a region of the blue photodiode.

Description

An image sensor and method for manufacturing an image sensor

An embodiment of the present invention discloses a method of manufacturing an image sensor, and relates to a method of manufacturing an image sensor capable of reducing the deterioration of characteristics in a blue photodiode region formed on a surface of a semiconductor substrate.

Recently, with the development of semiconductor technology, semiconductor sensors for converting images into electric signals have been developed. An image sensor is a representative semiconductor sensor that converts an image electrically. Representative image sensors include charge coupled device (CCD) sensors and CMOS image sensors.

The CCD sensor includes a plurality of MOS capacitors, which are operated by moving carriers generated by light. On the other hand, the CMOS image sensor includes a plurality of unit pixels and CMOS logic circuit for controlling the output signal of the unit pixel.

1 and 2 are views showing the configuration of a conventional image sensor.

Referring to FIG. 1, first, a red photodiode (1), a green photodiode (2), and a blue photodiode are fabricated through continuous epitaxial growth, implantation of impurity ions, and subsequent heat treatment processes in a semiconductor substrate. (5) is formed.

Then, plugs 3, 4, and 5 are formed to transmit the signals formed in each photodiode to the surface of the semiconductor substrate, and the signals thus transferred through the transistors 6 formed on the semiconductor substrate. Create an image.

As pixel size decreases in an image sensor having such a structure, isolation between photodiodes becomes important. To this end, as shown in FIG. 2, the insulating region 7 is formed by doping impurities for electrical insulation between the red photodiodes 1. Unexplained reference numeral 9 is an alignment key.

Then, a thermal process for stabilizing the doped impurities is performed, where lateral diffusion of the doped impurities occurs.

In the case of such CMOS image sensors, the most vulnerable to dark liquids is the blue photodiode. Since the blue photodiode is closest to the silicon surface among the photodiodes, damage occurs on the silicon surface during the photodiode and related implant processes, which causes surface leakage that causes dark current. One cause.

In order to prevent a specific degradation of the blue photodiode, a technique of performing a plurality of implant processes in a region between the device isolation layer and the blue photodiode has been proposed, but the problem of having to proceed with the implant process considerably have.

Therefore, there is a need to find a method of manufacturing an image sensor that can improve the characteristics of a blue photodiode.

SUMMARY OF THE INVENTION The present invention has been proposed to solve the above problems, and an object of the present invention is to propose a method of manufacturing an image sensor which can improve the characteristics of a blue diode and improve the silicon film quality to reduce surface package at the surface of a substrate.

An image sensor according to an embodiment of the present invention, a semiconductor substrate on which a red photodiode is formed; A first silicon epitaxial layer formed on the semiconductor substrate and including a green photodiode; A second silicon epitaxial layer formed on the first silicon epitaxial layer and having a blue photodiode; A first plug connected to one side of the green photodiode and penetrating the second silicon epi layer; A second plug connected to one side of the red photodiode and penetrating the first silicon epitaxial layer and the second silicon epitaxial layer; And an oxide film formed on the second silicon epi layer at a position corresponding to a region of the blue photodiode.

In addition, the manufacturing method of the image sensor of the embodiment comprises the steps of forming a first impurity region in the semiconductor substrate, and forming a red photodiode in the first impurity region; Forming an epitaxial layer of silicon on the semiconductor substrate using an epitaxial growth method; Forming a first plug in the first silicon epi layer connected to the red photodiode; Forming a second impurity region in the first silicon epitaxial layer and forming a green photodiode in the second impurity region; Forming a second silicon epilayer on the first silicon epilayer using epitaxial growth; Forming an isolation layer for the second silicon epi layer, defining an active region and forming a field region; Forming a well region in an active region between the device isolation layers; Forming a second plug connecting the green photodiode and the first plug in the second silicon epitaxial layer; And forming a blue photodiode by forming an oxide film having a predetermined thickness on the second silicon epitaxial layer and injecting impurities into the second silicon epitaxial layer disposed below the oxide film.

According to the proposed image sensor and a method of manufacturing the same, an oxide film is formed on the semiconductor substrate on the upper side of the blue photodiode so that no damage is applied to the region of the blue photodiode according to the subsequent impurity implantation process. Due to the improved silicon film quality, there is an advantage that can reduce the leakage in the blue photodiode region.

Hereinafter, with reference to the accompanying drawings for the present embodiment will be described in detail. However, the scope of the idea of the present invention may be determined from the matters disclosed by the present embodiment, and the idea of the invention of the present embodiment may be performed by adding, deleting, or modifying components to the proposed embodiment. It will be said to include variations.

In the following description, the word 'comprising' does not exclude the presence of other elements or steps than those listed.

3 to 14 are views for explaining a manufacturing method of an image sensor according to an embodiment of the present invention.

First, as shown in FIG. 3, an N-type semiconductor substrate 10 is prepared, and n-type impurities are implanted into the entire semiconductor substrate 10, thereby forming the n-type impurity region 20 in the semiconductor substrate 10. After the first photoresist pattern 21 is formed on the n-type impurity region 20 other than the P + type red photodiode 30, the first photoresist pattern 21 is formed. The impurity for forming the P + type red photodiode 30 is implanted into the n-type impurity region 20 by using.

After implanting the impurity into the n-type water-purity region 20 to form the P + type red photodiode 30, as shown in FIG. 4, an ashing process is performed to form the first photo on the n-type impurity region 20. The resist pattern 21 is removed, and the first silicon epitaxial layer 40 is epitaxially grown on the semiconductor substrate 10 provided with the P + type red photodiode 30, for example, TCS (SiHCl 3 ). It is formed by any one of the Molecular Beam Epitaxy (MBE) method and the Vapor Phase Epitaxy (VPE) method.

After forming the first silicon epi layer 40, as shown in FIG. 5, the second photoresist pattern 41 for forming the P + type first plug 50 on the first silicon epi layer 40. P + type impurities are injected into the first silicon epitaxial layer 40 using the second photoresist pattern 41 to form the P + type first plug 50.

Here, the P + type first plug 50 may be formed by selectively injecting metal ions, and electrically connects the P + type red photodiode 30 to a P + type green photodiode 70 formed thereafter.

After forming the P + type first plug 50, as shown in FIG. 6, the second photoresist pattern 41 is removed and the first silicon epitaxial layer 40 having the P + type first plug 50 is provided. The n-type impurity region 60 is formed by injecting the n-type impurity to the entirety.

After forming the n-type impurity region 60 of the first silicon epitaxial layer 40, as shown in FIG. 7, the P + type green photodiode 70 region and the P + type first plug 50 are opened. The third photoresist pattern 61 is formed, and the impurities for forming the P + type green photodiode 70 are formed through the third photoresist pattern 61 and the n type impurity region 60 and the P + type first plug. P + type green photodiode 70 is formed in n-type impurity region 60 by implantation into 50.

After forming the P + type green photodiode 70, an ashing process is performed to remove the third photoresist pattern 61. As shown in FIG. 8, the first type having the n-type impurity region 60 is provided. The second silicon epitaxial layer 80 is formed on the silicon ㅌ epitaxial layer 40. The second silicon epitaxial layer 80 may be epitaxially grown in the same manner as the first silicon epitaxial layer 40.

After forming the second silicon epitaxial layer 80, as shown in FIG. 9, a shallow trench isolation (STI) process is performed on the second silicon epitaxial layer 80 to define an active region and a field region. A device isolation film 90 for forming a film is formed.

After forming the device isolation layer 90 on the second silicon epitaxial layer 80, as shown in FIG. 10, the fourth photoresist pattern 91 opening the active region between the device isolation layer 90 is formed. The n-well 100 is formed by implanting n-type impurities into the second silicon epitaxial layer 80 using the fourth photoresist pattern 91 as an ion implantation mark.

After forming the n-well 100 in the second silicon epitaxial layer 80, as shown in FIG. 11, the fourth photoresist pattern 91 is removed and the P + type green photodiode 70 is removed. A fifth photoresist pattern 92 is formed on the second silicon epitaxial layer 80 to form two P + type second plugs 110 connected to or connected to the P + type first plug 50.

The P + type green photodiode 70 may be connected to the P + type green photodiode 70 by injecting P + impurities into the second silicon epitaxial layer 80 using the fifth photoresist pattern 92. To form a P + type second plug 111 connected to it.

After forming the second plug 110, as shown in FIG. 12, the fifth photoresist pattern 92 is removed by an ashing process, and the device isolation layer 90 is formed on the second silicon epitaxial layer 80. ) To form a sixth photoresist pattern 111 that opens the n-well 100 region therebetween.

In addition, an oxide layer 120 is deposited on the sixth photoresist pattern 111 and the exposed second silicon epitaxial layer 80.

The oxide layer 120 is formed to form a blue photodiode, and then the blue photodiode region is formed to reduce damage caused by a subsequent impurity process. And deposited on the exposed second silicon epitaxial layer 80.

In addition, an impurity implantation process may be performed to form a blue photodiode in the second silicon epitaxial layer 80 on which the oxide layer 120 is formed. In this case, impurities for forming the P + type blue photodiode 130 may be used. It is injected toward the oxide film 120.

In particular, the impurity implantation for forming the blue photodiode 130 injects a P-type impurity such as boron at a high energy of 50 to 100 KeV, and a dose amount of 10 13 to 10 14 pcs / cm 2.

After the impurity implantation process for forming the blue photodiode is performed after the deposition of the oxide film 120, as shown in FIG. 14, the sixth photoresist pattern 111 and the sixth photoresist pattern ( A process for removing the oxide film formed on the 111) is performed, and a lift-off process is performed using a material such as acetone.

That is, since the photoresist and the oxide formed on the photoresist are removed by the lift-off process, as shown in FIG. 14, the oxide film 130 at the position corresponding to the region where the blue photodiode is to be formed remains. Will be.

Next, although not shown, the subsequent process is performed in the same manner as the manufacturing process of a general vertical CMOS image sensor. That is, after forming an N-type source / drain region and forming a P + type source / drain region, a process of forming a contact and a subsequent Back End Of Layers (BEOL) process may be performed.

In particular, after the blue photodiode 130 is formed, the oxide film 120 is formed on the top surface of the blue photodiode 130, and the blue photodiode 130 is subsequently formed according to a subsequent impurity implantation process. Damage is not applied to the region of the film, thereby improving the silicon film quality to reduce the leakage in the blue photodiode region.

1 and 2 are views showing the configuration of a conventional image sensor.

3 to 14 are views for explaining a manufacturing method of an image sensor according to an embodiment of the present invention.

Claims (6)

Forming a first impurity region in the semiconductor substrate, and forming a red photodiode in the first impurity region; Forming an epitaxial layer of silicon on the semiconductor substrate using an epitaxial growth method; Forming a first plug in the first silicon epi layer connected to the red photodiode; Forming a second impurity region in the first silicon epitaxial layer and forming a green photodiode in the second impurity region; Forming a second silicon epi layer on the first silicon epi layer using an epitaxial growth method; Forming an isolation layer for the second silicon epi layer, defining an active region and forming a field region; Forming a well region in an active region between the device isolation layers; Forming a second plug connecting the green photodiode and the first plug in the second silicon epitaxial layer; And Forming a blue photodiode by forming an oxide film having a predetermined thickness on the second silicon epitaxial layer and injecting impurities into the second silicon epitaxial layer disposed below the oxide film. . The method of claim 1, Forming the blue photodiode, Forming a photoresist pattern on the second silicon epitaxial layer, the photoresist pattern exposing a surface of the second silicon epitaxial layer corresponding to a region where the blue photodiode is to be formed; Depositing an oxide film having a predetermined thickness on the photoresist pattern and the exposed second silicon epi layer; And implanting impurities into the second silicon epitaxial layer. The method of claim 2, Injecting the impurity for forming the blue photodiode into the second silicon epi layer, the dosing amount of 10 13 ~ 10 14 / cm 2 by the implantation energy of 50 ~ 100 KeV image Method of manufacturing the sensor. The method of claim 1, In the step of forming an oxide film having a predetermined thickness on the second silicon epitaxial layer, the oxide film is formed to a thickness of 500 ~ 1000Å. A semiconductor substrate on which a red photodiode is formed; A first silicon epitaxial layer formed on the semiconductor substrate and including a green photodiode; A second silicon epitaxial layer formed on the first silicon epitaxial layer and having a blue photodiode; A first plug connected to one side of the green photodiode and penetrating the second silicon epi layer; A second plug connected to one side of the red photodiode and penetrating the first silicon epitaxial layer and the second silicon epitaxial layer; And And an oxide film formed on the second silicon epitaxial layer at a position corresponding to the area of the blue photodiode. The method of claim 5, The oxide film is an image sensor, characterized in that formed to a thickness in the range of 500 ~ 1000Å.
KR1020080104004A 2008-10-23 2008-10-23 An image sensor and method for manufacturing an image sensor KR20100044994A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11749704B2 (en) 2019-11-04 2023-09-05 SK Hynix Inc. Method for forming photoelectric conversion element of image sensing device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11749704B2 (en) 2019-11-04 2023-09-05 SK Hynix Inc. Method for forming photoelectric conversion element of image sensing device

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