KR20100079087A

KR20100079087A - Image sensor and method for manufacturing the same

Info

Publication number: KR20100079087A
Application number: KR1020080137499A
Authority: KR
Inventors: 김승현
Original assignee: 주식회사 동부하이텍
Priority date: 2008-12-30
Filing date: 2008-12-30
Publication date: 2010-07-08

Abstract

PURPOSE: A back side of the manufacturing method thereof silver semiconductor substrate and image sensor is eliminated steadily. The sensitivity of the image sensor is improved. CONSTITUTION: A metal(141) and the first interlayer insulating film(142) are formed on the substrate. The bonding wafer(200) is bonded on the first interlayer insulating film. The second inter metal dielectric(150) is formed in the back side of substrate. The contact plug(162) is connected through the second inter metal dielectric and substrate to metal. The metal pad(170) is formed on the second inter metal dielectric. It is connected to the contact plug.

Description

Image sensor and method for manufacturing the same

This embodiment discloses an image sensor and a method of manufacturing the same.

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.

CMOS image sensors are currently widely used devices in mobile phones, personal computer (PC) cameras, and electronic devices.

The CMOS image sensor has a simpler driving method than the CCD used as an image sensor, and it is possible to integrate a signal processing circuit into a single chip so that the SOC (System On Chip) is possible, thereby miniaturizing the module.

Recently, in forming an image sensor, a backside illumination technique has been proposed, in which a backside of a substrate is shone to shine light onto the backside of the substrate instead of reducing the thickness of the interlayer insulating film.

The present embodiment proposes an image sensor and a method of manufacturing the same that can improve the sensitivity of the image sensor by removing the back surface of the semiconductor substrate.

The image sensor according to the present embodiment includes a substrate on which a photodiode is formed; A metal and a first interlayer insulating film formed on the substrate; A bonding wafer bonded on the first interlayer insulating film, the bonding wafer having a circuit; A second interlayer insulating film formed on the rear surface of the substrate; A contact plug connected to the metal through the second interlayer insulating layer and the substrate; And a metal pad formed on the second interlayer insulating layer and connected to the contact plug.

In addition, the manufacturing method of the image sensor of the embodiment comprises the steps of forming an oxide layer on the first substrate; Forming a second substrate on the oxide layer; Forming a photodiode in the second substrate; Forming a metal and a first interlayer insulating film on the second substrate; Bonding a bonding wafer having a circuit prepared in advance on the first interlayer insulating film; Exposing the back side of the second substrate by removing the oxide layer; And forming a contact plug penetrating the second substrate.

By the image sensor of the embodiment and the manufacturing method thereof as proposed, the back surface of the semiconductor substrate can be stably removed, thereby improving the sensitivity of the image sensor.

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. In addition, in the accompanying drawings, the thickness thereof is enlarged in order to clearly express various layers and regions. In addition, the same reference numerals are used for similar parts throughout the specification. When a part of a layer, film, region, plate, etc. is said to be "on" another part, this includes not only being another part "on top" but also having another part in the middle.

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 applicable to all image sensors, such as CCD image sensor.

1 is a diagram illustrating a configuration of an image sensor according to an exemplary embodiment.

Referring to FIG. 1, a photodiode 120 is formed on the silicon substrate 101 to generate an electrical signal for received light, and a transistor 130 is formed on the substrate 101.

In addition, a second interlayer insulating layer 150 on which a metal pad 170 is formed is formed on a back side of the substrate 101.

A plurality of metals 141 and a first interlayer insulating layer 142 are formed on the substrate 101, and the second interlayer insulating layer 150, the substrate 101, and the first interlayer insulating layer 142 are formed on the substrate 101. The contact plug 162 and the barrier layer 161 are formed in the through-holes. The metal pad 170 is electrically connected to the contact plug 162 formed in the via hole.

In addition, since the image sensor of the present exemplary embodiment has a structure in which light is incident on the rear surface of the substrate 101, a circuit having a plurality of transistors Tx, Rx, Dx, Sx, etc. is formed on the substrate 101. A bonding wafer 200 is formed, and the bonding wafer 200 is bonded on the first interlayer insulating layer 142.

By the image sensor having such a structure, the incident surface of the light and the photodiode for receiving the light are formed very close to each other, thereby improving the light receiving capability of the photodiode.

Hereinafter, a method of manufacturing the image sensor of the embodiment will be described with reference to FIGS. 2 to 11.

2 to 12 are diagrams for explaining the manufacturing method of the image sensor according to the present embodiment.

First, referring to FIGS. 2 and 3, a first silicon substrate 100 is prepared, and an oxide layer 110 is formed on the first silicon substrate 100.

The oxide layer 110 is removed by a subsequent wet etching process. A photodiode, a gate electrode, a metal, and the like are formed on the second substrate 101 to be formed on the first substrate 100. 1 serves to remove the substrate 100 more effectively.

According to the present embodiment, the oxide layer 110 may be formed to a thickness of 1000 kPa or more, and may be formed to a thickness of 1000 kPa to 3000 kPa.

Referring to FIG. 4, a second substrate 101 is formed on the oxide layer 110 by performing a bonding and cleaving process on a separate silicon substrate.

Therefore, the oxide layer 110 is interposed between the upper silicon substrate and the lower silicon substrate.

Next, referring to FIG. 5, a photodiode 120 is formed in the second substrate 101 to generate an electrical signal according to light reception, and a gate electrode or the like is formed on the second substrate 101. The transistor 130 is formed.

That is, the oxide layer 110 and the first substrate 100 are disposed on the rear surface of the second substrate 101, and the transistor 130 is formed on the upper surface of the second substrate 101.

Next, referring to FIG. 6, a plurality of metals 141 and a first interlayer insulating layer 142 are formed on the upper surface of the second substrate 101. Forming a plurality of metal lines and an interlayer insulating film on the second substrate 101 may be performed by a known method, and thus a detailed description thereof will be omitted.

Next, referring to FIG. 7, the circuit part 200 in which the plurality of gate electrodes, transistors, and metal lines are formed is bonded to the first interlayer insulating layer 142.

Here, the circuit unit 200 includes an electrical junction region and a plurality of transistors. In the description of the present embodiment, the circuit unit 200 is bonded to the interlayer insulating layer 142, which will be described below as a bonding wafer 200.

For reference, a bonding process may be performed by increasing the surface energy of the surface bonded by activation by plasma before bonding the bonding wafer 200 on the first interlayer insulating layer 142.

Next, referring to FIG. 8, the oxide layer 110 is removed using a wet chemical as a process for separating the first substrate 100 formed under the second substrate 101 on which the photodiode is formed. To perform the process.

Here, the wet chemical may use Dilute Hydrogen Fluoride (DHF), and the first substrate 100 may be separated from the second substrate 101 by wet removing the oxide layer 110.

As a result, as shown in FIG. 9, the rear surface of the second substrate 101 on which the photodiode and the transistor are formed is exposed. In particular, the back surface of the second substrate 101 exposed by the removal of the oxide layer 110 can secure the uniformity, and there is no need to planarize the back surface of the second substrate 101, which is manufactured. There is an advantage that can improve the characteristics of the device.

Next, referring to FIG. 10, a via hole 160 for electrically connecting the metal 141 formed on the first interlayer insulating layer 142 to the metal pad is performed.

Here, before performing the etching process for forming the via hole 160, a first insulating layer 151 may be formed on the rear surface of the second substrate 101 to reduce stress during the etching process.

In addition, the via hole 160 is formed by etching the first insulating layer 151, the second substrate 101, and the first interlayer insulating layer 142 so that a portion of the metal 141 may be exposed.

Next, referring to FIG. 11, the contact plug 162 is formed in the formed via hole to be connected to the metal 141.

The barrier layer 162 may be further formed in the via hole before the contact plug 161 is formed. After the metal gap fill process for forming the contact plug 161, a rear surface of the second substrate 101 may be formed. The CMP process can be carried out to expose this.

Next, referring to FIG. 12, a metal pad 170 connected to the contact plug 161 is formed on the first insulating layer 151, and a second insulating layer 152 is formed on the first insulating layer 151. ) To form the second interlayer insulating film 150.

By the image sensor having the structure as described above, the light receiving efficiency of the photodiode can be further improved, and the rear side of the silicon substrate can be effectively separated by removing the oxide layer.

1 is a diagram showing the configuration of an image sensor according to the present embodiment.

2 to 12 illustrate a method of manufacturing the image sensor according to the present embodiment.

Claims

A substrate on which a photodiode is formed;

A metal and a first interlayer insulating film formed on the substrate;

A bonding wafer bonded on the first interlayer insulating film, the bonding wafer having a circuit;

A second interlayer insulating film formed on the rear surface of the substrate;

A contact plug connected to the metal through the second interlayer insulating layer and the substrate; And

And a metal pad formed on the second interlayer insulating layer and connected to the contact plug.

The method of claim 1,

An image sensor having a barrier layer further formed on one side of the contact plug.

The method of claim 1,

The second interlayer insulating film includes a first insulating film formed on the rear surface of the substrate and a second insulating film formed on the first insulating film,

The metal pad is formed on the first insulating film.

Forming an oxide layer on the first substrate;

Forming a second substrate on the oxide layer;

Forming a photodiode in the second substrate;

Forming a metal and a first interlayer insulating film on the second substrate;

Bonding a bonding wafer having a circuit prepared in advance on the first interlayer insulating film;

Exposing the back side of the second substrate by removing the oxide layer; And

Forming a contact plug penetrating the second substrate.

The method of claim 4, wherein

The forming of the oxide layer may include forming an oxide having a thickness in the range of 1000 kPa to 3000 kPa on the first substrate.

The method of claim 4, wherein

Removing the oxide layer is a method of manufacturing an image sensor which is an oxide removal process using Dilute Hydrogen Fluoride (DHF).

The method of claim 4, wherein

The forming of the contact plug may include forming a second interlayer insulating film on a rear surface of the second substrate, forming a via hole penetrating through the second interlayer insulating film and the second substrate, and in the via hole. Forming a contact plug by gap filling the metal.

The method of claim 4, wherein

Prior to bonding the bonding wafer on the first interlayer insulating film, performing a plasma treatment on the bonded surface of the first interlayer insulating film or bonding wafer.