KR100901055B1 - Method for Manufacturing Image Sensor - Google Patents

Abstract

Method of manufacturing an image sensor according to the embodiment comprises the steps of forming a circuit (circuitry) on the substrate; Forming a wiring on the circuit; Forming a metal for a lower electrode on the wiring; Forming a photoresist pattern on the lower electrode metal; Selectively etching the lower electrode metal using the photoresist pattern as an etching mask to form a lower electrode; Removing the photoresist pattern remaining on the lower electrode with chemical oxide; And forming a photodiode on the lower electrode.

Image sensor, photodiode, lower electrode

Description

Method for Manufacturing Image Sensor

Embodiments relate to an image sensor.

In general, an image sensor is a semiconductor device that converts an optical image into an electrical signal, and is largely a charge coupled device (CCD) and a CMOS (Complementary Metal Oxide Silicon) image sensor. It is divided into (Image Sensor) (CIS).

In the CMOS image sensor, a photo diode and a MOS transistor are formed in a unit pixel to sequentially detect an electrical signal of each unit pixel in a switching manner to implement an image.

The CIS device according to the related art can be divided into a photo diode region for receiving a light signal and converting the light signal into an electrical signal, and a transistor region for processing the electrical signal.

However, the CMOS image sensor according to the related art has a structure in which a photodiode is horizontally disposed with a transistor.

Of course, although the disadvantages of the CCD image sensor are solved by the horizontal CMOS image sensor according to the prior art, there is still a problem in the horizontal CMOS image sensor according to the prior art.

That is, according to the horizontal CMOS image sensor of the prior art, a photodiode and a transistor are manufactured to be adjacent to each other horizontally on a substrate. Accordingly, an additional area for the photodiode is required, thereby reducing the fill factor area and limiting the possibility of resolution.

In addition, according to the horizontal CMOS image sensor according to the prior art there is a problem that it is very difficult to achieve optimization for the process of manufacturing the photodiode and the transistor at the same time. That is, in a fast transistor process, a shallow junction is required for low sheet resistance, but such shallow junction may not be appropriate for a photodiode.

In addition, according to the horizontal CMOS image sensor according to the prior art, the size of the unit pixel is increased to maintain the sensor sensitivity of the image sensor as additional on-chip functions are added to the image sensor. The area for the photodiode must be reduced to maintain the pixel size. However, when the pixel size is increased, the resolution of the image sensor is reduced, and when the area of the photodiode is reduced, the sensor sensitivity of the image sensor is reduced.

Embodiments provide an image sensor and a method of manufacturing the same that can provide a new integration of a circuit and a photodiode.

In addition, the embodiment is to provide an image sensor without the attack of the lower electrode for the photodiode present on the circuit and a manufacturing method thereof.

In addition, embodiments provide an image sensor and a method of manufacturing the same that can prevent cross talk between pixels.

In addition, the embodiment is to provide an image sensor and a method of manufacturing the same that can be improved with the resolution (Resolution) and sensor sensitivity (sensitivity).

In addition, the embodiment is to provide an image sensor and a manufacturing method thereof that can prevent the defect in the photodiode while employing a vertical photodiode.

The image sensor according to the embodiment includes a circuit (circuitry) formed on the substrate; Wiring formed above the circuit; A lower electrode formed on the wiring; An oxide formed on the side of the lower electrode; And a photodiode formed on the lower electrode.

In addition, the manufacturing method of the image sensor according to the embodiment comprises the steps of forming a circuit (circuitry) on the substrate; Forming a wiring on the circuit; Forming a metal for a lower electrode on the wiring; Forming a photoresist pattern on the lower electrode metal; Selectively etching the lower electrode metal using the photoresist pattern as an etching mask to form a lower electrode; Removing the photoresist pattern remaining on the lower electrode with chemical oxide; And forming a photodiode on the lower electrode.

According to the image sensor and the manufacturing method thereof according to the embodiment, it is possible to provide a vertical integration of the transistor circuit (circuitry) and the photodiode.

In addition, according to the embodiment, when the photoresist pattern is removed after the lower electrode pattern of the photodiode on the upper side of the circuit, the photoresist pattern may be removed without attack on the lower electrode by using chemical oxide.

In addition, according to the embodiment, the presence of oxide on the lower electrode side prevents crosstalk between pixels.

In addition, according to the embodiment, the fill factor can be approached to 100% by vertical integration of the transistor circuit and the photodiode.

Further, according to the embodiment, it is possible to provide higher sensitivity at the same pixel size by vertical integration than in the prior art.

In addition, according to the embodiment it is possible to reduce the process cost for the same resolution (Resolution) than the prior art.

In addition, according to the exemplary embodiment, each unit pixel may implement a more complicated circuit without reducing the sensitivity.

In addition, the additional on-chip circuitry that can be integrated by the embodiment can increase the performance of the image sensor and further reduce the size and manufacturing cost of the device.

Further, according to the embodiment, it is possible to prevent defects in the photodiode while employing a vertical photodiode.

Hereinafter, an image sensor and a method of manufacturing the same according to an embodiment will be described in detail with reference to the accompanying drawings.

In the description of the embodiments, where it is described as being formed "on / under" of each layer, it is understood that the phase is formed directly or indirectly through another layer. It includes everything.

In the description of the embodiment will be described with reference to the structure of the CMOS image sensor (CIS), the present invention is not limited to the CMOS image sensor, it is applied to all image sensors employing a photodiode, such as CCD image sensor This is possible.

(Example)

1 is a cross-sectional view of an image sensor according to an embodiment.

An image sensor according to an embodiment includes a circuit (not shown) formed on a substrate (not shown); A wiring 145 formed above the circuit; A lower electrode 150 formed on the wiring 145; An oxide 160 formed on a side surface of the lower electrode 150; An intrinsic layer 180 formed on the lower electrode 150; A second conductivity type conductive layer 190 formed on the intrinsic layer 180; And an upper electrode 197 formed on the second conductivity type conductive layer 190.

In an embodiment, the photodiode 195 may include an intrinsic layer 180 and a second conductivity type conductive layer 190.

In addition, in the embodiment, the photodiode 195 may further include a first conductivity type conductive layer 170 formed between the lower electrode 150 and the intrinsic layer 180.

The wiring 145 is formed on the interlayer insulating layer 120 on the substrate and may include a metal 130 and a plug 140.

According to the image sensor according to the embodiment, it is possible to provide a vertical integration of the transistor circuit (circuitry) and the photodiode.

In addition, according to the exemplary embodiment, when the photoresist pattern is removed after the lower electrode 150 pattern for the photodiode 195 existing above the circuit, the oxide 160 is disposed on the side surface of the lower electrode 150 using chemical oxide. ), The photoresist pattern may be removed without attacking the lower electrode 150.

In addition, according to the exemplary embodiment, the oxide 160 is present on the side of the lower electrode 150 to prevent crosstalk between pixels.

A method of manufacturing an image sensor according to an embodiment will be described with reference to FIGS. 2 to 6.

First, a circuit (not shown) is formed on a substrate (not shown) as shown in FIG. 2, and a wiring 145 is formed above the circuit. The wiring 145 may include a metal 130 and a plug 140. The plug 140 may be formed of tungsten (W), but is not limited thereto.

Thereafter, a lower electrode metal 150a is formed on the wiring 145. For example, the lower electrode metal 150a may be formed of various conductive materials including metals, alloys, or silicides. For example, the lower electrode metal 150a may be formed of aluminum, copper, cobalt, or the like.

Thereafter, a photoresist pattern 210 is formed on the lower electrode metal 150a. For example, the photoresist pattern 210 may be present on the wiring 145.

Next, as shown in FIG. 3, the lower electrode metal 150a is selectively etched using the photoresist pattern 210 as an etch mask to form the lower electrode 150. For example, although the lower electrode 150 may be formed by etching by reactive ion etching (RIE), the etching method is not limited thereto.

In this case, the photoresist pattern 210a remaining on the lower electrode 150 remains as shown in FIG. 3.

In an embodiment, as illustrated in FIG. 4, the remaining photoresist layer pattern 210a may be removed by chemical oxide. That is, in the embodiment, ozone water (O ₃ water) may be used to remove the remaining photoresist pattern 210a and not to attack the lower electrode 150.

For example, ozone water (O ₃ water) removes the remaining photoresist pattern 210a formed of carbon.

At this time, as shown in FIG. 5, the ozone water removes the remaining photoresist pattern 201a on the lower electrode 150 and forms a thin oxide 160 on the sidewall of the lower electrode 150. Therefore, the lower electrode 150 does not receive an attack. For example, an oxide 160 of about 10 to about 20 kW may be formed on the sidewall of the lower electrode 150.

In this way, the lower electrode 150 may be patterned while removing the photoresist pattern 210a remaining in ozone water (O ₃ Water) while preventing attack on the lower electrode 150.

For example, the process condition of chemical oxide using ozone water (O ₃ water) is 30 ~ 60sec process time per sheet for single type equipment, and 600 ~ 1200sec for bath type equipment. The process takes time, the flow rate (flow rate) is about 1 ~ 2ℓ / min, ozone concentration (O ₃ concentration) is about 5 ~ 10ppm, RPM may be about 400 ~ 600rpm when the single type equipment. Through such process conditions, the lower electrode 150 may be patterned while preventing attack on the lower electrode 150 while removing the photoresist pattern 210a remaining in ozone water (O ₃ Water).

Next, as shown in FIG. 6, a first conductivity type conductive layer 170 is formed on the lower electrode 150. In some cases, the first conductive type conductive layer 170 may not be formed and subsequent processes may be performed. The first conductivity type conductive layer 170 may serve as the N layer of the PIN diode employed in the embodiment. That is, the first conductivity type conductive layer 170 may be an N type conductivity type conductive layer, but is not limited thereto.

The first conductivity type conductive layer 170 may be formed using N-doped amorphous silicon, but is not limited thereto. That is, the first conductivity type conductive layer 170 is a-Si: H, a-SiGe: H, a-SiC, a-SiN: H a- by adding germanium, carbon, nitrogen or oxygen to amorphous silicon. SiO: H or the like.

Thereafter, an intrinsic layer 180 is formed on the first conductivity type conductive layer 170. The intrinsic layer 180 may serve as the I layer of the PIN diode employed in the embodiment.

The intrinsic layer 180 may be formed using amorphous silicon. The intrinsic layer 180 may be formed by chemical vapor deposition (CVD), in particular, PECVD. For example, the intrinsic layer 180 may be formed of amorphous silicon by PECVD using silane gas (SiH ₄ ).

Thereafter, a second conductivity type conductive layer 190 is formed on the intrinsic layer 180. The second conductivity type conductive layer 190 may be formed in a continuous process with the formation of the intrinsic layer 180. The second conductivity type conductive layer 190 may serve as the P layer of the PIN diode employed in the embodiment. That is, the second conductive conductive layer 190 may be a P type conductive conductive layer, but is not limited thereto.

The second conductivity type conductive layer 190 may be formed using P-doped amorphous silicon, but is not limited thereto. The second conductivity type conductive layer 190 may be formed by chemical vapor deposition (CVD), in particular, PECVD. For example, the second conductivity type conductive layer 190 may be formed of amorphous silicon by PECVD by mixing boron or the like with silane gas (SiH ₄ ).

Thereafter, an upper electrode 197 is formed on the second conductivity type conductive layer 190. The upper electrode 197 may be formed as a transparent electrode having high light transmittance and high conductivity. For example, the upper electrode 197 may be formed of indium tin oxide (ITO) or cardium tin oxide (CTO).

According to the image sensor and the manufacturing method thereof according to the embodiment, it is possible to provide a vertical integration of the transistor circuit (circuitry) and the photodiode.

In addition, according to the embodiment, when the photoresist pattern is removed after the lower electrode pattern of the photodiode on the upper side of the circuit, the photoresist pattern may be removed without attack on the lower electrode by using chemical oxide.

In addition, according to the embodiment, the presence of oxide on the lower electrode side prevents crosstalk between pixels.

In addition, according to the embodiment, the fill factor can be approached to 100% by vertical integration of the transistor circuit and the photodiode.

Further, according to the embodiment, it is possible to provide higher sensitivity at the same pixel size by vertical integration than in the prior art.

In addition, according to the embodiment it is possible to reduce the process cost for the same resolution (Resolution) than the prior art.

In addition, according to the exemplary embodiment, each unit pixel may implement a more complicated circuit without reducing the sensitivity.

In addition, the additional on-chip circuitry that can be integrated by the embodiment can increase the performance of the image sensor and further reduce the size and manufacturing cost of the device.

Further, according to the embodiment, it is possible to prevent defects in the photodiode while employing a vertical photodiode.

The present invention is not limited to the described embodiments and drawings, and various other embodiments are possible within the scope of the claims.

1 is a cross-sectional view of an image sensor according to an embodiment.

2 to 6 are process cross-sectional views of a manufacturing method of an image sensor according to an embodiment.

Claims (5)

Forming a circuit in the substrate; Forming a wiring on the circuit; Forming a metal for a lower electrode on the wiring; Forming a photoresist pattern on the lower electrode metal; Selectively etching the lower electrode metal using the photoresist pattern as an etching mask to form a lower electrode; Removing the photoresist pattern remaining on the lower electrode with chemical oxide; And Forming a photodiode on the lower electrode; And removing a chemical oxide from the photoresist pattern remaining on the lower electrode, wherein an oxide is formed on a side of the lower electrode. According to claim 1, Forming the photodiode, Forming an intrinsic layer on the lower electrode; And And forming a second conductive type conductive layer on the intrinsic layer. The method according to claim 1 or 2, The chemical oxide is ozone water (O ₃ water) manufacturing method of the image sensor, characterized in that. delete The method of claim 3, wherein Process conditions of the chemical oxide (chemical oxide) using the ozone water (O ₃ water) is 30 ~ 60sec process time, bath type (bath type) equipment per sheet for a single type (equipment) It takes 600 ~ 1200sec process time, the flow rate (flow rate) for each equipment (flow rate) is 1 ~ 2ℓ / min, ozone concentration (O ₃ concentration) is a manufacturing method of the image sensor, characterized in that 5 ~ 10ppm.

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