Image sensor formation method capable of protecting surface of substrate

专利摘要:
PURPOSE: An image sensor manufacturing method is provided to improve the reliability of a photodiode by protecting the surface of a semiconductor substrate or an epitaxial layer through several processes. CONSTITUTION: After forming field oxides(31), a gate insulating layer(32) and a gate electrode(33) of a transfer transistor, n-type dopant region(34) of a photodiode region is formed by selectively implanting doped ions. A nitride(35) and an oxide are sequentially formed on the entire surface of the resultant structure. Then, oxide spacers(36A) are formed on both sidewalls of the gate electrode(33) by entirely etching the oxide using the nitride(35) as an etch stopper, thereby protecting a surface of a photodiode. A p-type dopant region(37) is formed in the n-type dopant region(34) of the photodiode and a floating diffusion region(38) is then formed by implanting heavily doped dopants.
公开号:KR20020052791A
申请号:KR1020000082236
申请日:2000-12-26
公开日:2002-07-04
发明作者:황준
申请人:박종섭；주식회사 하이닉스반도체；
IPC主号:

专利说明:

Image sensor formation method capable of protecting surface of substrate
[9] TECHNICAL FIELD The present invention relates to the field of image sensor manufacturing, and more particularly, to an image sensor manufacturing method capable of protecting a substrate surface.
[10] An image sensor is an apparatus that converts optical information of one or two dimensions or more into an electrical signal. The types of image sensors are broadly classified into imaging tubes and solid-state imaging devices. Imaging tubes are widely used in measurement, control, and recognition using image processing technology centered on televisions, and applied technologies have been developed. There are two types of solid-state image sensors on the market: metal-oxide-semiconductor (MOS) type and charge coupled device (CCD) type.
[11] CMOS image sensor is a device that converts an optical image into an electrical signal by using CMOS fabrication technology, and adopts a switching method in which MOS transistors are made by the number of pixels and the outputs are sequentially detected using the same. The CMOS image sensor has a simpler driving method than the CCD image sensor which is widely used as a conventional image sensor, and can implement various scanning methods, and can integrate a signal processing circuit into a single chip, thereby miniaturizing the product. The use of compatible CMOS technology reduces manufacturing costs and significantly lowers power consumption.
[12] 1 is a circuit diagram showing a unit pixel of a CMOS image sensor composed of four transistors and two capacitors, and a unit pixel of a CMOS image sensor composed of a photodiode (PD) and four NMOS transistors for optical sensing. . Of the four NMOS transistors, the transfer transistor Tx transports the photocharges generated by the photodiode PD to the floating diffusion, and the reset transistor Rx transmits the floating diffusion region for signal detection. The drive transistor Dx serves as a source follower, and the select transistor Sx serves for switching and addressing. In the drawing, "Cf" represents capacitance of the floating diffusion region, and "Cp" represents capacitance of the photodiode.
[13] Operation of the image sensor unit pixel configured as described above is performed as follows. Initially, the unit pixel is reset by turning on the reset transistor Rx, the transfer transistor Tx, and the select transistor Sx. At this time, the photodiode PD starts to deplete, and the capacitance Cp generates carrier charging, and the capacitance Cf of the floating diffusion region is charged and stored up to the supply voltage VDD. The transfer transistor Tx is turned off, the select transistor Sx is turned on, and the reset transistor Rx is turned off. In such an operating state, the output voltage V1 is read from the unit pixel output terminal Out and stored in the buffer, and then the carrier transistor Tx is turned on to move the carriers of the capacitance Cp changed according to the light intensity to the capacitance Cf. The output voltage (V2) is read from the output terminal (Out) again and the analog data for V1-V2 is converted into digital data, so one operation cycle for the unit pixel is completed.
[14] 2A through 2C are cross-sectional views of a manufacturing process of a CMOS image sensor according to the related art, and illustrate a process of forming a photodiode for detecting a photoelectric sensor, a gate electrode of a transfer transistor for photocharge transfer, and a floating diffusion region. Hereinafter, a CMOS image sensor manufacturing method according to the prior art will be described in detail with reference to FIGS. 2A to 2C.
[15] First, as shown in FIG. 2A, the field oxide film 21 for device isolation is formed on the p-type silicon substrate 20, the gate insulating film 22 and the gate electrode 23 of the transfer transistor are formed, and then selectively. An ion implantation process is performed to form the n-type impurity region 24 of the photodiode region.
[16] Next, as shown in Fig. 2B, an oxide film 25 for forming a spacer is formed on the entire structure.
[17] Subsequently, as shown in FIG. 2C, the oxide film 25 is completely etched to form an oxide film spacer 25A on the sidewall of the gate electrode 23, and the p-type impurity region 26 is formed on the n-type impurity region of the photodiode. Next, n ⁺ ion implantation process is performed to form the floating diffusion region 27.
[18] In the conventional image sensor manufacturing method including the above-described process, the surface of the semiconductor substrate or the surface of the epitaxial layer formed on the semiconductor substrate is damaged by continuous etching, ion implantation, and cleaning using various chemicals. . Therefore, since the surface of the photodiode to be used most perfectly is severely damaged, there is a problem in that it cannot produce a uniform electron-hole pair for light energy, thereby deteriorating the reliability of the CMOS image sensor.
[19] The present invention for solving the above problems, to provide a method for manufacturing an image sensor that can prevent the surface of the photodiode to be damaged by protecting the surface of the semiconductor substrate surface or the epitaxial layer in various process steps. have.
[1] 1 is a circuit diagram schematically showing a unit pixel structure of a conventional CMOS image sensor;
[2] 2A to 2C are cross-sectional views of a CMOS image sensor manufacturing process according to the prior art
[3] 3A-3D are cross-sectional views of a CMOS image sensor fabrication process in accordance with an embodiment of the present invention.
[4] * Description of reference numerals for the main parts of the drawings *
[5] 30: semiconductor substrate 33: gate electrode
[6] 34: n-type impurity region 35: nitride film
[7] 36A: oxide film spacer 37: p-type impurity region
[8] 38: n-type floating diffusion region
[20] The present invention for achieving the above object is a first step of forming a gate electrode on a semiconductor substrate of the first conductivity type; A second step of forming a first impurity region of a second conductivity type in the semiconductor substrate at one end of the gate electrode; A third step of forming a nitride film on the entire structure in which the second step is completed; Forming an oxide film on the nitride film; A fifth step of forming an oxide spacer on the nitride layer covering the gate electrode sidewall by etching the oxide layer on the entire surface; A sixth step of ion implanting impurities of a first conductivity type on the first impurity region to form a second impurity region forming a photodiode with the semiconductor substrate and the first impurity region; And a seventh step of forming a floating diffusion region by ion implanting impurities of a first conductivity type into the semiconductor substrate at the other end of the gate electrode.
[21] The present invention is characterized in that a nitride film is formed on a semiconductor substrate surface or an epitaxial layer to protect the photodiode surface from various process steps, thereby improving the reliability of the photodiode.
[22] Hereinafter, a method of manufacturing an image sensor according to an exemplary embodiment of the present invention will be described with reference to FIGS. 3A to 3D.
[23] First, as shown in FIG. 3A, the field oxide layer 31 for device isolation is formed on the p-type silicon substrate 30, and the gate insulating layer 32 and the gate electrode 33 of the transfer transistor are formed. An ion implantation process is performed to form an n-type impurity region 34 of the photodiode region.
[24] Next, as shown in FIG. 3B, a nitride film 35 having a thickness of 50 GPa to 200 GPa is formed on the entire structure, and an oxide film 36 for forming a spacer is formed on the nitride film 35.
[25] Subsequently, as shown in FIG. 3C, the oxide film 36 is etched entirely to form an oxide spacer 36A on the nitride film 35 covering the sidewalls of the gate electrode 33, and then on the n-type impurity region of the photodiode. After forming the p-type impurity region 37, an n ⁺ ion implantation process is performed to form the floating diffusion region 38, which also forms the source and drain of the transistor.
[26] Next, as shown in FIG. 3D, the first interlayer insulating film 39 is formed of BPSG (borophospho silicate glass) on the entire structure, and the metal wiring 40, the second interlayer insulating film 41, and the color filter array ( 42 is formed, and then the OCM 43 is applied on the entire structure and the microlens 44 is formed to overlap with the color filter array 42.
[27] The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the art without departing from the technical spirit of the present invention. It will be apparent to those of ordinary knowledge.
[28] The present invention made as described above can increase the margin of the etching process as the nitride layer serves as an etch stop layer during the etching process for forming the oxide spacer, and the surface of the photodiode in the frequent etching, cleaning, ion implantation process, etc. It is possible to protect the semiconductor substrate or epitaxial layer.

权利要求:
Claims (2)
[1" claim-type="Currently amended] In the image sensor manufacturing method,
Forming a gate electrode on the first conductive semiconductor substrate;
A second step of forming a first impurity region of a second conductivity type in the semiconductor substrate at one end of the gate electrode;
A third step of forming a nitride film on the entire structure in which the second step is completed;
Forming an oxide film on the nitride film;
A fifth step of forming an oxide spacer on the nitride layer covering the gate electrode sidewall by etching the oxide layer on the entire surface;
A sixth step of ion implanting impurities of a first conductivity type on the first impurity region to form a second impurity region forming a photodiode with the semiconductor substrate and the first impurity region; And
A seventh step of forming a floating diffusion region by implanting impurities of a first conductivity type into the semiconductor substrate at the other end of the gate electrode
Image sensor manufacturing method comprising a.
[2" claim-type="Currently amended] The method of claim 1,
The nitride film is formed in a 50 kHz to 200 kHz thickness, characterized in that the image sensor manufacturing method.

类似技术:

---

公开号 | 公开日 | 专利标题

---

US10529765B2|2020-01-07|Solid-state imaging device having through electrode provided therein and electronic apparatus including the solid-state imaging device

---

US9437631B2|2016-09-06|Solid-state imaging device, manufacturing method of the same, and electronic apparatus

---

US7880255B2|2011-02-01|Pixel cell having a grated interface

---

CN100377362C|2008-03-26|Image sensing device and its manufacturing method

---

JP4224036B2|2009-02-12|Image sensor with embedded photodiode region and method of manufacturing the same

---

US6787386B2|2004-09-07|Method of forming a photodiode for an image sensor

---

JP4739324B2|2011-08-03|Image sensor with embedded photodiode region and method of manufacturing the same

---

US7166879B2|2007-01-23|Photogate for use in an imaging device

---

TW531906B|2003-05-11|CMOS image sensor capable of increasing punch-through voltage and charge integration of photodiode, and method for forming the same

---

KR100672669B1|2007-01-24|CMOS Image sensor and method for fabricating the same

---

US7973346B2|2011-07-05|Image sensor with self-boosting transfer transistor gate and methods of operating and fabricating the same

---

KR20120090352A|2012-08-17|Image sensor

---

KR100714484B1|2007-05-04|Image sensor and method for fabricating the same

---

US8624310B2|2014-01-07|Image sensors with lightly doped drain | to reduce dark current

---

JP4472236B2|2010-06-02|CMOS image sensor

---

KR20060060695A|2006-06-05|Imaging with gate controlled charge storage

---

KR100672701B1|2007-01-22|CMOS Image sensor and method for fabricating the same

---

US6656760B2|2003-12-02|Solid state imaging sensor in a submicron technology and method of manufacturing and use of a solid state imaging sensor

---

US20060157758A1|2006-07-20|Image sensor and pixel having an optimized floating diffusion

---

JP2008541491A|2008-11-20|Imaging device comprising a pixel cell having a transparent conductive coupling line and method for making the pixel cell

---

KR100614650B1|2006-08-22|Image sensor and method for forming the same

---

KR100760913B1|2007-09-21|CMOS Image Sensor and Method for Manufacturing the same

---

KR100561004B1|2006-03-16|CMOS Image Sensor And Method For Manufacturing The Same

---

KR100477784B1|2005-03-22|Image sensor having lens formed by air in trench and method for fabricating the same

---

US7675100B2|2010-03-09|CMOS image sensor and method for fabricating the same

同族专利:

---

公开号 | 公开日

---

引用文献:

---

公开号 | 申请日 | 公开日 | 申请人 | 专利标题

---

法律状态:
2000-12-26|Application filed by 박종섭, 주식회사 하이닉스반도체

---

2000-12-26|Priority to KR1020000082236A

---

2002-07-04|Publication of KR20020052791A

优先权:

---

申请号 | 申请日 | 专利标题

---

KR1020000082236A|KR20020052791A|2000-12-26|2000-12-26|Image sensor formation method capable of protecting surface of substrate|