KR20110068679A

KR20110068679A - Image sensor and method for manufacturing thereof

Info

Publication number: KR20110068679A
Application number: KR1020090125746A
Authority: KR
Inventors: 정승만
Original assignee: 주식회사 동부하이텍
Priority date: 2009-12-16
Filing date: 2009-12-16
Publication date: 2011-06-22

Abstract

PURPOSE: An image sensor and manufacturing method thereof are provided to reduce unnecessary optical paths between a micro lens and a photo diode, thereby increasing the performance of the image sensor. CONSTITUTION: A semiconductor substrate comprises light receiving elements. A circuit layer comprises a PMD film formed on the semiconductor substrate. A metal wiring layer comprises an IMD film and a metal wire formed on the PMD film. A deep trench(60) corresponds to the light receiving elements on the IMD film and the PMD film. A capping film(65) protects the deep trench and the metal wire. A color filter is formed in the deep trench. A protective film(75) covers the color filter and the metal wire. A lens is formed on the protective film.

Description

Image sensor and manufacturing method thereof {IMAGE SENSOR AND METHOD FOR MANUFACTURING THEREOF}

Embodiments relate to an image sensor and a manufacturing method thereof.

An image sensor is a semiconductor device that converts an optical image into an electrical signal. The image sensor is largely a charge coupled device (CCD) and a complementary metal oxide silicon (CMOS) image sensor. (CIS).

CMOS image sensors are devices that digitize light with IMAGING technology. 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 structure of the CMOS image sensor is briefly divided into a light receiving unit, a filter unit, a sensor unit, and a circuit unit. The key to imaging technology is to filter the incoming light and digitize the image without losing any light.

However, the CMOS image sensor adopts a structure in which many layers are stacked for a wiring process, and the light entering the layers of the stacked structure has a problem of being extinguished by diffraction or affecting adjacent pixels.

The embodiment provides an image sensor and a method of manufacturing the same that can improve the optical characteristics of the image sensor, thereby improving the light sensitivity.

The embodiment provides an image sensor and a method of manufacturing the same, which use light entering the image sensor without loss and can exclude interference with adjacent pixels.

The embodiment provides an image sensor and a method of manufacturing the same that reduce the number of photo processes.

An image sensor according to an embodiment includes a semiconductor substrate including light receiving elements, a circuit layer including a PMD film formed on the semiconductor substrate, an metal interconnection layer including an IMD film and a metal wiring formed on the PMD film, and the light receiving device. A deep trench formed in the IMD film and the PMD film, a capping film surrounding the deep trench and the metal wiring, a color filter formed in the deep trench, a protective film covering the color filter and the metal wiring, and a passivation film formed on the protective film. It includes a lens.

According to an embodiment, there is provided a method of manufacturing an image sensor, the method including: forming a circuit layer including a circuit and a PMD film on a semiconductor substrate including a light receiving element, and including an IMD film and metal wiring connected to the circuit on the circuit layer; Forming a metal wiring layer, forming a deep trench corresponding to the photodiode by etching a portion of the IMD film and the PMD film using the metal wiring as a mask, and forming a color filter in the deep trench; Forming a passivation layer on the color filter and the metal line; and forming a lens corresponding to the deep trench on the passivation layer.

The image sensor and the method of manufacturing the same according to the embodiment have the effect of improving the performance of the image sensor by reducing the unnecessary light path between the microlens and the photodiode by applying a color filter to the trenches in the PMD and the IMD.

In addition, since light from the microlenses is separated through the color filter and received directly by the photodiode, cross talk can be prevented, thereby preventing noise from being generated and improving image quality. There is.

The embodiment has the effect of reducing the number of photo processes to reduce the cost and simplify the process.

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

1 to 7 are process cross-sectional views of a method of manufacturing an image sensor according to an embodiment.

First, as shown in FIG. 1, an isolation layer 11 and a light receiving element 12 are formed on a semiconductor substrate 10.

The light receiving element 12 may be a photodiode.

The device isolation layer 11 may be formed by etching the semiconductor substrate 10 to a predetermined depth to form the trench 11, and filling the insulating layer in the trench 11. The device isolation layer 11 may be referred to as shallow trench isolation (STI).

As shown in FIG. 2, the circuit layer 20 may be formed on the semiconductor substrate 10.

The circuit layer 20 may be a circuit including transistors and a pre metal dielectric (PMD) layer covering the circuit.

The circuit may include, but is not limited to, a transfer transistor, a reset transistor, a drive transistor, a select transistor, and the like.

The circuit of the circuit layer 20 may be electrically connected to the light receiving element 12 to generate a signal using photocharges integrated in the light receiving element 12.

3 and 4, a metal wiring layer 50 is formed on the circuit layer 20.

The metal wiring layer 50 forms a metal wiring connected to the circuit on the PMD film of the circuit layer 20, and forms an inter metal dielectric (IMD) film covering the metal wiring.

The metal wiring layer 50 may be formed of a single metal wiring or a multilayer metal wiring. When the metal wiring layer is formed of a multilayer metal wiring, the metal wiring and the IMD film are alternately formed.

The metal wire may be made of various metal materials, and may include aluminum, copper, titanium, tantalum, or the like.

The metal wire including aluminum may deposit a metal layer including aluminum on an insulating layer, and pattern the metal layer to form a metal wire.

The metal wiring containing copper may form a trench in an insulating film, and metal wiring may be formed by filling a metal in the trench using a method such as electroplating.

The IMD film may be an oxide film. For example, the oxide film constituting the IMD film may be a xylene oxide film deposited by using a silica (SiH ₄ ) gas.

In the embodiment of FIG. 4, the metal wiring layer 50 includes a first metal wiring 31 formed on a PMD film, a first IMD film 41 covering the first metal wiring 31, and a first IMD film 41. ) May include a second metal wiring 32 formed on the second metal wiring 32, a second IMD film 42 covering the second metal wiring 32, and a third metal wiring 33 formed on the second IMD film 42. . However, the present invention is not limited thereto and may be a metal wiring layer including a single metal wiring and a single insulating film, or a metal wiring layer having a structure in which more metal wiring and insulating films are stacked. The metal wires are electrically connected to each other.

Here, the third metal wiring 33 may refer to the metal wiring of the uppermost layer in the metal wiring layer 50 of the image sensor.

The third metal wire 33 may be formed of a metal wire including aluminum.

The third metal wire 33 may be formed thicker than the first and second metal wires 31 and 32. This is to secure an etching margin when forming a trench corresponding to the light receiving element 12 by using the third metal wiring 33.

The third metal wiring 33 forms a metal wiring layer 50 with a thickness of 3000 kV to 8000 kPa, forms a photoresist pattern 90 on the metal wiring layer 50, and etches the metal layer with a mask to form a metal layer. The three metal wiring 33 can be formed.

As shown in FIG. 5, the IMD corresponds to the photoresist pattern 90 remaining on the third metal wiring 33 and the photodiode 12 using the third metal wiring 33 as a mask. The layers 41 and 42 and the PMD layer may be etched to form a deep trench 60 for the color filter.

The depth of the deep trench 60 may include a portion of the PMD layer from the second IMD layer 42, that is, the uppermost IMD layer. The deep trench 60 does not completely remove the PMD film and does not expose the light receiving element 12.

Since the third metal wiring 33 is formed only in an area in which the light is not received in the image sensor, that is, in an area other than the optical path between the light receiving elements 12 in the microlens 80, the third metal wiring 33 is formed. When the IMD film and the PMD are etched using (33) as a mark, the deep trench 60 may be formed in a region corresponding to the light receiving element 12.

The width of the deep trench 60 may be larger than the width of the light receiving element 12.

The deep trench 60 may expose a portion of the first metal wiring 31 or the second metal wiring 32 therein.

The deep trench 60 may be formed to correspond to the light receiving element 12 and may be formed along a path of light incident from the image sensor.

Subsequently, as illustrated in FIG. 6, the capping layer 65 is formed on the metal wiring layer 50 including the deep trench 60. The capping layer 65 may be formed of the oxide layer.

The capping film 65 may be formed to have a thickness of 1000 ns to 4000 ns.

The capping layer 65 may protect the exposed metal wires by forming the third metal wire 33 on the inner surface of the deep trench 60.

Meanwhile, the capping film 65 formed on the bottom surface of the deep trench 60 may be removed by selectively removing the capping film 65. In this case, an upper surface of the third metal wire 33 may also be removed. Such a process may use an anisotropic plasma etching process with strong straightness. At this time, by removing the capping film 65 formed on the bottom surface of the deep trench 60, the light transmittance can be increased by increasing the light transmittance.

Subsequently, as illustrated in FIG. 7, a first photosensitive color filter 71 is formed on the metal wiring layer 50 to be embedded in at least one of the deep trenches 65.

The first photosensitive color filter 71 may be formed by exposing the first photosensitive color filter layer with a pattern mask and then developing the first photosensitive color filter 71.

As shown in FIG. 6, the second photosensitive color filter 72 is formed in at least one of the deep trenches 60 in which the first photosensitive color filter filter 71 is not embedded.

The second photosensitive color filter 72 may be formed by exposing the second photosensitive color filter layer with a pattern mask and then developing the second photosensitive color filter 72.

Thereafter, a third photosensitive color filter 73 is formed in at least one of the deep trenches 60.

The third photosensitive color filter 73 may be formed by exposing the third photosensitive color filter layer with a pattern mask and then developing the third photosensitive color filter 73.

The first to third photosensitive color filters 71, 72, and 73 may include at least one of red, green, and blue color filter materials.

As such, a photosensitive color filter material may be embedded in each of the deep trenches 60 formed in the semiconductor substrate 10 to form a color filter array corresponding to each pixel.

The heights of the first to third photosensitive color filters 71, 72, and 73 may be different from each other, and the heights may be decreased in the order of red, green, and blue. This is because the first to third photosensitive color filters 71, 72, and 73 have different wavelengths depending on the color of the color filter.

The passivation layer 75 is formed on the semiconductor substrate 10 in which the color filter array is formed in the trench 60.

Thereafter, a micro lens 80 may be formed on the first to third photosensitive color filters 71, 72, and 73 to correspond to the unit pixels.

In addition, the image sensor according to the embodiment does not need to configure a separate color filter array by forming a color filter array in the deep trench, thereby preventing unnecessary loss of light by reducing a path of unnecessary light and good at low light quantity. It may have a light efficiency.

In addition, since the color filter array layer may be omitted, the thickness of the image sensor may be reduced.

Although described above with reference to the embodiments, which are merely examples and are not intended to limit the present invention. Those skilled in the art to which the present invention pertains are not exemplified above without departing from the essential characteristics of the present invention. It will be appreciated that many variations and applications are possible. For example, each component specifically shown in the embodiments of the present invention can be modified and implemented. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

Claims

A semiconductor substrate including light receiving elements;

A circuit layer including a PMD film formed on the semiconductor substrate;

A metal wiring layer including an IMD film and a metal wiring formed on the PMD film;

A deep trench formed in the IMD film and the PMD film in correspondence with the light receiving device;

A capping layer surrounding the deep trench and the metal wiring;

A color filter formed in the deep trench;

A protective layer covering the color filter and the metal wiring; And

An image sensor comprising a lens formed on the protective film.

The method of claim 1,

The metal wiring is the uppermost metal wiring in the metal wiring layer, the image sensor having a thickness of 3000 ~ 8000Å.

The method of claim 1,

The metal wiring layer may further include an additional metal wiring and an additional IMD layer under the metal wiring, wherein the metal wiring is thicker than the additional metal wiring.

The method of claim 1,

The capping film is an image sensor having a thickness of 3000 ~ 8000Å.

The method of claim 1,

The capping layer exposes the bottom surface of the deep trench and the top surface of the metal wiring.

The method of claim 3, wherein

And the capping layer covers the additional metal wire exposed on the side of the deep trench.

The method of claim 1,

The capping film is an oxide film.

The method of claim 1,

And an upper surface of the metal line and the protective layer contact each other.

Forming a circuit layer including a circuit and a PMD film on a semiconductor substrate including a light receiving element;

Forming a metal wiring layer on the circuit layer, the metal wiring layer including an IMD film and a metal wiring connected to the circuit;

Etching a portion of the IMD layer and the PMD layer using the metal wiring as a mask to form a deep trench corresponding to the photodiode;

Forming a color filter in the deep trench;

Forming a protective film on the color filter and the metal wiring; And

And forming a lens corresponding to the deep trench on the passivation layer.

10. The method of claim 9,

After forming the deep trench,

And forming a capping layer on the deep trench and the metallization.

The method of claim 10,

The capping film is a manufacturing method of the image sensor, characterized in that the oxide film.

The method of claim 10,

And anisotropically etching the capping layer to expose the bottom surface of the deep trench and the metallization.

10. The method of claim 9,

The metal wiring is an uppermost metal wiring of the metal wiring layer, and further comprising an additional metal wiring under the metal wiring.

The method of claim 13,

And the metallization is thicker than the additional metallization.