KR20140141823A - Image sensor having isolation structure and method for fabricating the same - Google Patents

Abstract

The present invention relates to an image sensor having an element isolation structure and a method of fabricating the same for preventing crosstalk. Provided is the image sensor including: an element isolation structure including a first isolation structure including an insulation layer filling a gap of a trench formed in a substrate and a second isolation structure including a first impurity region formed in the substrate and a second impurity region formed along an edge of the first impurity region, in which the second impurity region has an impurity doping concentration greater than that of the first impurity region; and an optical conversion region formed on the substrate to correspond to the plurality of pixels isolated by the element isolation structure.

Description

FIELD OF THE INVENTION [0001] The present invention relates to an image sensor having an element isolation structure,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device manufacturing technology, and more particularly, to an image sensor having a device isolation structure and a method of manufacturing the same.

An image sensor is a semiconductor device that converts an optical image into an electrical signal. The image sensor may be classified into a CCD (charge coupled device) type and a CMOS type (complementary metal oxide semiconductor type). CMOS image sensors are generally referred to as 'CIS (CMOS image sensor)'. The CIS has a plurality of pixels arranged two-dimensionally, and each pixel is separated by a device isolation structure. Each of the pixels separated by the element isolation structure includes a photodiode (PD). The photodiode serves to convert incident light into an electrical signal.

2. Description of the Related Art In recent years, with the development of semiconductor device manufacturing technology, high integration of image sensors has been accelerated. As the size of each of the pixels and the interval between the pixels become smaller due to such high integration, there is a problem that the characteristics are deteriorated by the cross talk between the pixels.

An embodiment of the present invention provides an image sensor having an element isolation structure capable of preventing crosstalk and a method of manufacturing the same.

An image sensor according to an exemplary embodiment of the present invention includes a first element isolation region including an insulating film that fills a trench formed in a substrate, a first impurity region formed on the substrate, and a second impurity region formed along the edge of the first impurity region, A device isolation structure in which a second device isolation structure including a second impurity region having a large impurity doping concentration is stacked; And a photoelectric conversion region formed on the substrate corresponding to the plurality of pixels separated by the device isolation structure.

A method of manufacturing an image sensor according to an embodiment of the present invention includes: forming a photoelectric conversion region on a substrate corresponding to a plurality of pixels; Forming a trench in a substrate between the photoelectric conversion regions; Forming an amorphous region in the substrate below the trench, the amorphous region having a lower melting temperature than the substrate; Implanting impurities into the amorphous region; And melting the amorphous region to activate the implanted impurities and annealing to recrystallize the impurities.

The present technology based on the solution of the above-mentioned problems can effectively prevent physical crosstalk and electrical crosstalk between adjacent pixels by providing a device isolation structure in which the first device isolation and the second device isolation are laminated .

Further, in the second element isolation, the impurity doping concentration of the second impurity region surrounding the first impurity region is larger, so that the electrical crosstalk can be more effectively prevented.

In addition, the annealing process for selectively melting the amorphous region can prevent characteristic deterioration due to the diffusion of the implanted impurities and reduce the thermal burden imposed on the preformed structure.

1 is an equivalent circuit diagram of an image sensor according to an embodiment of the present invention.
2 is a plan view of an image sensor according to embodiments of the present invention;
FIG. 3A is a sectional view showing an image sensor according to a first embodiment of the present invention; FIG.
3B is a cross-sectional view showing a modified example of the image sensor according to the first embodiment of the present invention.
4A to 4E are cross-sectional views illustrating a method of manufacturing an image sensor according to a first embodiment of the present invention.
5A is a sectional view showing an image sensor according to a second embodiment of the present invention.
5B is a cross-sectional view showing a modified example of the image sensor according to the second embodiment of the present invention.
6A to 6E are process sectional views showing a method of manufacturing an image sensor according to a second embodiment of the present invention.
7A is a sectional view showing an image sensor according to a third embodiment of the present invention;
7B is a cross-sectional view showing a modification of the image sensor according to the third embodiment of the present invention.
8A to 8G are process sectional views showing a method of manufacturing an image sensor according to a third embodiment of the present invention.
9 is a graph showing impurity doping concentration of an impurity region formed through laser annealing including selective melting.
10 is a graph showing the melting of silicon having different crystal structures depending on laser irradiation energy.
11 is an image showing lattice movement according to laser annealing.
12 is a block diagram showing the configuration of an image sensor according to an embodiment of the present invention;
13 is a block diagram illustrating a system including an image sensor in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, in order to facilitate a person skilled in the art to easily carry out the technical idea of the present invention.

In the embodiments of the present invention described below, an image sensor having an element isolation structure capable of preventing cross talk between adjacent pixels in an image sensor having a plurality of pixels, and a method of manufacturing the same to provide. To this end, embodiments of the present invention provide a device isolation structure having different indices of refraction from the substrate corresponding to each of the pixels. In particular, embodiments of the present invention provide an element isolation structure having a refractive index that is smaller than the substrate corresponding to each pixel. More specifically, embodiments of the present invention act as a potential barrier to isolate a first device including an insulating film having a smaller refractive index than the substrate and to block the movement of a carrier, An element isolation structure having a structure in which a second element isolation layer including an impurity region having a refractive index smaller than that of the substrate is laminated, an image sensor having the element isolation structure, and a method of manufacturing the element isolation structure. Here, the impurity region having a refractive index smaller than that of the substrate may be doped to the substrate or alloyed with the substrate to induce the substrate to have a refractive index smaller than that of the substrate. For reference, forming the impurity region so as to have a smaller refractive index than the substrate is for inducing total reflection. In addition, 'doping' or 'alloy' means that the impurity implanted into the substrate forms a bond with a material constituting the substrate.

Meanwhile, the image sensor can classify a CCD type (charge coupled device type) and a CMOS type (complementary metal oxide semiconductor type), and a CMOS type image sensor can be classified into a front-side illumination (FSI) (Back-Side Illumination, BSI). In the following description, the technical idea of the present invention will be described in detail by exemplifying an image sensor of the back irradiation type.

1 is an equivalent circuit diagram of an image sensor according to an embodiment of the present invention.

1, each pixel of the image sensor according to the embodiment includes a photoelectric conversion region PD, a transfer transistor Tx, a selection transistor Sx, a reset transistor Rx, and an access transistor Ax. . ≪ / RTI > The photoelectric conversion region PD may include a plurality of vertically overlapping photoelectric conversion portions. Each of the photoelectric conversion portions may be a photodiode including an N-type impurity region and a P-type impurity region. The transfer gate of the transfer transistor (Tx) can extend into the substrate. That is, the transfer gate may have a form of a recess gate, a saddle-fin gate, or a buried gate. The drain of the transfer transistor Tx can be understood as the floating diffusion region FD. The floating diffusion region FD may be a source of a reset transistor Rx. The floating diffusion region FD may be electrically connected to the selection gate of the selection transistor Sx. The selection transistor Sx and the reset transistor Rx may be connected in series. The selection transistor Sx is connected to an access transistor Ax. The reset transistor Rx, the selection transistor Sx and the access transistor Ax can be shared with each other by neighboring pixels, whereby the degree of integration can be improved.

The operation of the image sensor according to the embodiment will be described with reference to FIG. First, in a state in which light is blocked, a power supply voltage VDD is applied to the drain of the reset transistor Rx and the drain of the selection transistor Sx to discharge the charges remaining in the floating diffusion region FD. Thereafter, when the reset transistor Rx is turned off and light from the outside is incident on the photoelectric conversion region PD, an electron-hole pair is generated in the photoelectric conversion region PD . The generated holes are a P-type impurity region, and the generated electrons move to and accumulate in the N-type impurity region. When the transfer transistor Tx is turned ON, charges such as accumulated electrons and holes are transferred to and accumulated in the floating diffusion region FD. The gate bias of the selection transistor Sx changes in proportion to the accumulated charge amount, resulting in a change in the source potential of the selection transistor Sx. At this time, when the access transistor Ax is turned on, a signal by charge is read to the column line.

Here, as the image sensor is highly integrated, the size of each of the pixels and the interval between the pixels gradually decreases, and the characteristic deterioration due to the interference between adjacent pixels, that is, the deterioration of characteristics due to the crosstalk is intensified. In order to prevent such crosstalk, a substrate is formed with a device isolation structure for separating the pixels from each other.

The element isolation structure may be an impurity region formed by ion implanting an impurity into the substrate, or an insulated region where an insulator is embedded in the trench formed in the substrate. The impurity region serves as a potential barrier for blocking the carrier transferring between the pixels, thereby preventing electrical crosstalk. However, the impurity region can not prevent the physical crosstalk due to the incident light, and it is very difficult to control the diffusion of the impurity in the forming process, so that the degree of integration of the device isolation structure can not be increased. There is a drawback that it causes property deterioration. On the other hand, the insulating region is advantageous in that it is easy to integrate and can prevent physical crosstalk and electrical crosstalk due to incident light. However, due to a number of defects existing on the surface and dangling bonds, There is a disadvantage in that the insulating region itself serves as a cause of occurrence of dark current.

Therefore, in the embodiments of the present invention described below, an image sensor having an element isolation structure capable of preventing electrical crosstalk due to charge transfer and physical cross-talk due to incident light, And a method for producing the same will be described in detail.

FIG. 2 is a plan view of an image sensor according to an embodiment of the present invention, and FIGS. 3A and 3B are cross-sectional views taken along line A-A 'shown in FIG. FIG. 3A is a cross-sectional view illustrating an image sensor according to a first embodiment of the present invention, and FIG. 3B is a cross-sectional view illustrating a modified example of the image sensor according to the first embodiment of the present invention.

2, 3A and 3B, the image sensor according to the embodiment includes a first device isolation 110 formed on a substrate 101 and separating a plurality of pixels, And a photoelectric conversion region PD formed on the substrate 101 corresponding to each of the pixels separated by the device isolation structure 130 and the device isolation structure 130. The substrate 101 may include a semiconductor substrate. The semiconductor substrate may be in a single crystal state, and may include a silicon-containing material. That is, the substrate 101 may comprise a single crystal silicon containing material.

The photoelectric conversion region PD may include a plurality of vertically overlapping photoelectric conversion units, and each of the photoelectric conversion units may be a photodiode including an N-type impurity region and a P-type impurity region. The photoelectric conversion region PD and the element isolation structure 130 may have a predetermined spacing.

The first device isolation 110 may include an insulating film 112 for tapping the trench 111 formed in the substrate 101. The trenches 111 may have vertical sidewalls, or may have sloped sidewalls. The shape of the trench 111 sidewall (or the slope of the sidewall) can be adjusted to control the path of the incident light. The insulating film 112 may be any one single film selected from the group consisting of an oxide film having a refractive index lower than that of the substrate 101 including the photoelectric conversion region PD, a nitride film, and a nitride oxide film, or two or more laminated laminated films. In one example, when the substrate 101 includes a silicon-containing material, the insulating film 112 may include a silicon oxynitride film.

The second isolation 120 may have an impurity region that has a smaller refractive index than the substrate 101 including the photoelectric conversion region PD and that acts as a potential barrier for the photoelectric conversion region PD. Here, the impurity region having a refractive index smaller than that of the substrate 101 including the photoelectric conversion region PD may be a doped or alloyed region in which an impurity which induces a refractive index smaller than that of the substrate 101, . ≪ / RTI > The impurity region serving as a potential barrier with respect to the photoelectric conversion region PD may have a conductivity type complementary to that of the photoelectric conversion region PD facing the side wall. More specifically, when the conductivity type of the photoelectric conversion region PD facing the side wall of each other is N-type, the conductivity type of the impurity region may be P-type. That is, the impurity region may be a substrate 101 doped with a P-type impurity, and the P-type impurity may include a P-type metal. For example, when the substrate 101 includes a silicon-containing material, silver (Ag), cobalt (Co), iron (Fe) or the like may be used as the P type metal, And has a lower refractive index than silicon. Conversely, when the conductivity type of the photoelectric conversion region PD facing the side wall of each other is P type, the conductivity type of the impurity region may be N type, and the N type impurity may include N type metal. For example, when the substrate 101 includes a silicon-containing material, aluminum (Al), titanium (Ti) or the like may be used as the N-type metal, and the N-type metal combined with the silicon may have a refractive index lower than that of silicon .

The impurity region constituting the second element isolation 120 may be formed through an impurity ion implantation process and an annealing process. Depending on the characteristics of the annealing process, impurities implanted along the edge of the impurity region may accumulate ) Shape (see Fig. 9). Specifically, the second isolation 120 includes a first impurity region 121 and a second impurity region 121 formed along the edge of the first impurity region 121 and having an impurity doping concentration larger than that of the first impurity region 121 122). The impurity doping concentration of the second impurity region 122 is greater than that of the first impurity region 121, so that the potential barrier size at the impurity region boundary surface is further increased to effectively prevent the electrical crosstalk. The first impurity region 121 and the second impurity region 122 may be simultaneously formed by the characteristics of the annealing process.

In addition, the first device isolation 110 and the second device isolation 120 of the device isolation structure 130 according to the embodiment may have a vertically overlapping structure. Specifically, the first device isolation 110 may have a structure in which the first device isolation 110 is stacked on the second device isolation 120 with reference to the back-side of the substrate 101 (see FIG. 3A) (See FIG. 3B) in which the second device isolation 120 is stacked on the first substrate 110. The device isolation structure 130 having a structure in which the first device isolation 110 is stacked on the second device isolation 120 on the basis of the back-side of the substrate 101 can more effectively prevent the physical cross- And the device isolation structure 130 having a structure in which the second device isolation 120 is stacked on the first device isolation 110 on the basis of the back-side of the substrate 101, Can be effectively prevented. Accordingly, the positions of the first device isolation 110 and the second device isolation 120 in the device isolation structure 130 can be selected according to the required device characteristics. The element isolation structure 130 may have a depth greater than the depth of the photoelectric conversion region PD with respect to the front side of the substrate 101. This is to improve separation characteristics between adjacent pixels and to prevent crosstalk more effectively. In one example, the device isolation structure 130 may have a shape that penetrates the substrate 101.

The image sensor according to the embodiment includes an interlayer insulating film 103 formed on the front surface of a substrate 101, a signal generating circuit formed inside the interlayer insulating film 103, a protective film formed between the substrate 101 and the interlayer insulating film 103 102). The signal generating circuit generates (or outputs) an electrical signal corresponding to the charge generated in the photoelectric conversion region PD. Specifically, the signal generating circuit may include a plurality of transistors and a multi-layered metal wiring 104. The plurality of transistors may include a transfer transistor Tx, a reset transistor Rx, a selection transistor Sx, and an access transistor Ax. The multi-layered metal wiring 104 can be electrically connected to the plurality of transistors and the plurality of metal wirings 104 through a plurality of contact plugs (not shown). The protective film 102 serves to prevent damage to the inter-process signal generating circuit, particularly, the multi-layered metal wiring 104. The protective film 102 may include a material film having lower thermal conductivity than the substrate 101 and may be a single film or a laminated film using a material film having lower thermal conductivity than the substrate 101. For example, in the case where the substrate 101 includes a silicon-containing material, the protective film 102 may include a silicon-containing insulating film 112 and a metal-containing insulating film 112. The silicon-containing insulating film 112 may include a silicon oxide film (SiO ₂ ), and the metal containing insulating film 112 may include a zirconium oxide film (ZrO ₂ ).

The image sensor according to the embodiment may include a color filter 105 formed on the back-side of the substrate 101 and a microlens 106 formed on the color filter 105.

The image sensor having the above-described structure includes the element isolation structure 130 in which the first element isolation 110 and the second element isolation 120 vertically overlap, thereby effectively preventing physical and electrical crosstalk between adjacent pixels can do.

In addition, since the element isolation structure 130 has a refractive index smaller than that of the substrate 101 including the photoelectric conversion region PD, it is possible to more effectively prevent physical crosstalk between adjacent pixels.

In addition, since the impurity doping concentration of the second impurity region 122 surrounding the first impurity region 121 is larger, it is possible to more effectively prevent the electrical crosstalk.

FIGS. 4A to 4E are cross-sectional views illustrating a method of manufacturing the image sensor according to the first embodiment of the present invention, and are views for explaining an example of the method of manufacturing the image sensor shown in FIG. 3A.

As shown in Fig. 4A, a substrate 11 on which a plurality of pixels are defined is prepared. The substrate 11 may include a semiconductor substrate. The semiconductor substrate may be in a single crystal state, and may include a silicon-containing material. That is, the substrate 11 may include a single crystal silicon-containing material.

Next, the substrate 11 is selectively etched along the boundary region where the plurality of pixels contact with each other to form the trench 12 for the first device isolation. The trenches 12 may have vertical sidewalls to control the path of incident light, or may be formed with inclined sidewalls. The etching process for forming the trenches 12 can proceed by dry etching.

Next, an insulating film 13 is formed so as to cover the trenches 12. The insulating film 13 may be formed through a series of processes in which the insulating film 13 is formed on the substrate 11 so as to cover the trench 12 and then the planarization process is performed until the surface of the substrate 11 is exposed. The insulating film 13 may be any one single film selected from the group consisting of an oxide film, a nitride film, and a nitrided oxide film having a refractive index lower than that of the substrate 11 corresponding to each of the pixels, or two or more laminated laminated films.

Thereby, the first element isolation 14 including the insulating film 13 which fills the trench 12 formed in the substrate 11 can be formed.

Next, a photoelectric conversion region PD is formed in the substrate 11 so as to correspond to each pixel. The photoelectric conversion region PD may include a plurality of vertically overlapping photoelectric conversion portions, and each of the photoelectric conversion portions may be a photodiode including an N-type impurity region and a P-type impurity region. The photodiode can be formed through an impurity ion implantation process.

The protective film 15 is formed on the substrate 11 including the first element isolation region 14 and the photoelectric conversion region PD, as shown in Fig. 4B. The protective film 15 may be formed of a material film having lower thermal conductivity than the substrate 11 and may be formed of a single film or a laminated film using a material film having lower thermal conductivity than the substrate 11. [ For example, in the case where the substrate 11 includes a silicon-containing material, the protective film 15 may be formed of a silicon-containing insulating film and / or a metal-containing insulating film. The silicon-containing insulating film may include a silicon oxide film (SiO ₂ ), and the metal-containing insulating film may include a zirconium oxide film (ZrO ₂ ).

Next, an interlayer insulating film 16 including a signal generating circuit is formed on the protective film 15. The interlayer insulating film 16 may be any one selected from the group consisting of an oxide film, a nitride film, and a nitrided oxide film, and may have a multilayer structure. The signal generating circuit generates (or outputs) an electrical signal corresponding to the charge generated in the photoelectric conversion region PD. Specifically, the signal generating circuit may include a plurality of transistors and a multi-layered metal wiring 17. The plurality of transistors may include a transfer transistor Tx, a reset transistor Rx, a selection transistor Sx, and an access transistor Ax. The multilayer metal wiring 17 can be electrically connected to the plurality of transistors and the plurality of metal wirings 17 through a plurality of contact plugs (not shown).

Although not shown in the drawing, the thickness of the substrate 11 can be reduced by performing a thinning process on the back-side of the substrate 11 after the signal generating circuit is formed. This is to increase the light receiving efficiency by reducing the distance of incident light incident on the photoelectric conversion region PD. The thinning process can be performed by backgrinding and polishing.

A mask pattern (not shown) is formed on the back-side of the substrate 11 after the substrate 11 on which the signal generating circuit is formed is inverted as shown in FIG. 4C. The mask pattern may have a shape that opens only a region where the element isolation structure is to be formed. That is, the mask pattern may have a shape in which the rear surface of the substrate 11 corresponding to the first element isolation 14 formed on the front side of the substrate 11 is opened.

Next, pre-amorphization is performed in which a mask pattern (not shown) is implanted with impurities into the back surface of the substrate 11 with an ion implantation barrier. When the substrate 11 is a silicon-containing material, impurities such as germanium (Ge), silicon (Si), carbon (C) and the like can be used as the impurity for pre-amorphization. The amorphous region 18 can be formed in the substrate 11 through the linear amorphization and the bottom surface of the amorphous region 18 can be formed in contact with the bottom surface of the first element isolation 14. [

Line amorphization is intended to form an amorphous region 18 having a lower melting temperature than the substrate 11 in the single crystal state. Specifically, the amorphous region 18 formed through the linear amorphization may have a lower melting temperature than the substrate 11 in the single crystal state. For example, amorphous silicon has a melting temperature as low as about 200 캜 lower than monocrystalline silicon.

4D, a mask pattern (not shown) is introduced into the amorphous region 18 as an ion implantation barrier so as to have a refractive index smaller than that of the substrate 11 including the photoelectric conversion region PD, ) Is implanted by ion implantation. Hereinafter, the reference numeral of the amorphous region 18 into which the impurity is implanted is changed to " 19 "

The impurity which can induce a refractive index smaller than that of the substrate 11 including the photoelectric conversion region PD may include a metal and the impurity capable of forming a potential barrier for the photoelectric conversion region PD may be an adjacent photoelectric conversion May mean an impurity having a conductive type complementary to the conductive type of the region PD. For example, when the conductivity type of the photoelectric conversion region PD having the side wall facing the amorphous region 19 is N-type, the P-type metal can be used as an impurity in the ion implantation process.

As shown in FIG. 4E, an annealing process is performed to activate the impurities injected into the amorphous region 19 and recrystallize the amorphous region 19. The annealing is selectively performed only on the amorphous region 19 in order to prevent the deterioration of the characteristics due to the diffusion of the impurities implanted in the annealing process and to reduce the thermal burden imposed on the preformed structure. For this purpose, the annealing process can proceed to a laser anneal capable of local annealing.

The annealing process using laser annealing is performed by irradiating the laser to the amorphous region 19 doped with impurities for a predetermined time to melt the amorphous region 19 having a relatively low melting temperature with respect to the single crystal substrate 11 , The molten amorphous region 19 is solidified from the point of time when the laser irradiation is stopped, and is recrystallized into a single crystal state, and at the same time, the injected impurities are activated. At this time, even if the laser is irradiated on the substrate 11 due to the difference in melting temperature between the single crystal substrate 11 and the amorphous region 19, the substrate 11 is not melted. That is, selective melting is possible as the amorphous region 19 is formed (see FIG. 10).

Thereby, the second impurity region 20 and the second impurity region 21 including the second impurity region 21 formed along the edge of the first impurity region 20 and having an impurity doping concentration larger than that of the first impurity region 20 (22) can be formed. It is possible to recrystallize the amorphous region 19 by melting the impurity-doped amorphous region 19 during the annealing process, to improve the activation rate of the doped impurities, to accumulate impurities injected into the boundary region during the recrystallization process the second isolation 22 including the first impurity region 20 and the second impurity region 21 can be easily formed (see FIG. 9).

On the other hand, in the annealing process, the protective film 15 including the material film having lower thermal conductivity than the substrate 11 can prevent the pre-formed signal generating circuit, particularly, the multilayer metal wiring 17 from being damaged.

Next, an image sensor can be completed using a known manufacturing technique. For example, a color filter and a microlens are sequentially formed on the back surface of the substrate 11 including the device isolation structure 23 including the first device isolation 14 and the second device isolation 22 vertically stacked, Can be completed.

The image sensor formed through the above-described manufacturing method has the element isolation structure 23 in which the first element isolation 14 and the second element isolation 22 vertically overlap with each other so that the physical and electrical crosstalk between adjacent pixels Can be effectively prevented.

In addition, since the element isolation structure 23 has a refractive index smaller than that of the substrate 11 including the photoelectric conversion region PD, it is possible to more effectively prevent physical crosstalk between adjacent pixels.

In addition, the second isolation 22 can more effectively prevent the electrical crosstalk because the impurity doping concentration of the second impurity region 21 surrounding the first impurity region 20 is larger.

The annealing process for selectively melting the amorphous region 19 having a lower melting temperature than that of the substrate 11 in a single crystal state prevents characteristic deterioration due to the diffusion of the implanted impurities, The thermal burden can be reduced.

5A and 5B are cross-sectional views taken along line A-A 'shown in FIG. FIG. 5A is a sectional view showing an image sensor according to a second embodiment of the present invention, and FIG. 5B is a sectional view showing a modified example of the image sensor according to the second embodiment of the present invention.

2, 5A and 5B, the image sensor according to the embodiment includes a first device isolation 210 and a second device isolation 220 formed on a substrate 201 to separate a plurality of pixels, And a photoelectric conversion region PD formed on the substrate 201 corresponding to each of the pixels separated by the device isolation structure 230 and the device isolation structure 230 including the device isolation structure 230. The substrate 201 may include a semiconductor substrate. The semiconductor substrate may be in a single crystal state, and may include a silicon-containing material. That is, the substrate 201 may include a single crystal silicon-containing material.

The photoelectric conversion region PD may include a plurality of vertically overlapping photoelectric conversion units, and each of the photoelectric conversion units may be a photodiode including an N-type impurity region and a P-type impurity region. The photoelectric conversion region PD and the element isolation structure 230 may be spaced apart from each other by a predetermined distance.

The first device isolation 210 may include an insulating film 212 for tapping the trench 211 formed in the substrate 201. The trenches 211 may have vertical sidewalls, or may have sloped sidewalls. The shape of the sidewalls of the trenches 211 can be adjusted to control the path of the incident light. The insulating film 212 may be any one single film selected from the group consisting of an oxide film having a refractive index lower than that of the substrate 201 including the photoelectric conversion region PD, a nitride film, and a nitride oxide film, or two or more laminated laminated films. In one example, when the substrate 201 includes a silicon-containing material, the insulating film 212 may include a silicon oxynitride film.

The second element isolation 220 may have an impurity region that has a smaller refractive index than the substrate 201 including the photoelectric conversion region PD and functions as a potential barrier for the photoelectric conversion region PD. Here, the impurity region having a refractive index smaller than that of the substrate 201 including the photoelectric conversion region PD may be doped or alloyed regions that are coupled with the material constituting the substrate 201 and induce a refractive index smaller than that of the substrate 201 . ≪ / RTI > The impurity region serving as a potential barrier with respect to the photoelectric conversion region PD may have a conductivity type complementary to that of the photoelectric conversion region PD facing the side wall. More specifically, when the conductivity type of the photoelectric conversion region PD facing the side wall of each other is N-type, the conductivity type of the impurity region may be P-type. That is, the impurity region may be a substrate 201 doped with a P-type impurity, and the P-type impurity may include a P-type metal. For example, when the substrate 201 includes a silicon-containing material, silver (Ag), cobalt (Co), iron (Fe) or the like may be used as the P type metal, And has a lower refractive index than silicon. Conversely, when the conductivity type of the photoelectric conversion region PD facing the side wall of each other is P type, the conductivity type of the impurity region may be N type, and the N type impurity may include N type metal. For example, when the substrate 201 includes a silicon-containing material, aluminum (Al), titanium (Ti), or the like may be used as the N-type metal, and the N-type metal combined with the silicon may have a lower refractive index .

The impurity region constituting the second element isolation 220 may be formed through an impurity ion implantation process and an anneal process. If the impurity implanted along the edge of the impurity region is accumulated due to the annealing process characteristics, (See FIG. 9). Specifically, the second isolation 220 includes a first impurity region 221, a second impurity region 221 formed along the edge of the first impurity region 221 and having an impurity doping concentration larger than that of the first impurity region 221 222 and a third impurity region 223 extending between the substrate 201 and the first device isolation 210. Since the impurity doping concentration of the second impurity region 222 is larger than that of the first impurity region 221, the potential barrier size at the impurity region interface can be increased to more effectively prevent electrical crosstalk. The third impurity region 223 formed between the substrate 201 and the first device isolation 210 is formed by removing dangling bonds and defects at the interface between the first device isolation 210 and the substrate 201, Thereby preventing the occurrence of the problem.

In addition, the first device isolation 210 and the second device isolation 220 of the device isolation structure 230 according to the embodiment may have a vertically overlapping structure. Specifically, the first device isolation 210 may have a structure in which the first device isolation 210 is stacked on the second device isolation 220 with reference to the back-side of the substrate 201 (see FIG. 5B) (See FIG. 5A) in which the second element isolation 220 is stacked on the first element isolation layer 210 (see FIG. 5A). The element isolation structure 230 having a structure in which the first element isolation 210 is stacked on the second element isolation 220 with reference to the back-side of the substrate 201 can more effectively prevent physical crosstalk due to incident light And the element isolation structure 230 having the structure in which the second element isolation 220 is stacked on the first element isolation 210 with reference to the back-side of the substrate 201, Can be effectively prevented. Therefore, the positions of the first device isolation 210 and the second device isolation 220 in the device isolation structure 230 can be selected according to the required device characteristics. The element isolation structure 230 may have a depth greater than the depth of the photoelectric conversion region PD based on the front-side of the substrate 201. This is to improve separation characteristics between adjacent pixels and to prevent crosstalk more effectively. For example, the device isolation structure 230 may have a shape penetrating through the substrate 201.

The image sensor according to the embodiment includes an interlayer insulating film 203 formed on the front surface of a substrate 201, a signal generating circuit formed inside the interlayer insulating film 203, and a protective film formed between the substrate 201 and the interlayer insulating film 203 202). The signal generating circuit generates (or outputs) an electrical signal corresponding to the charge generated in the photoelectric conversion region PD. Specifically, the signal generating circuit may include a plurality of transistors and a multi-layered metal wiring 204. The plurality of transistors may include a transfer transistor Tx, a reset transistor Rx, a selection transistor Sx, and an access transistor Ax. The multi-layered metal wiring 204 may be electrically connected to the plurality of transistors and the plurality of metal wirings 204 through a plurality of contact plugs (not shown). The protective film 202 serves to prevent the inter-process signal generating circuit, particularly, the multilayer metal wiring 204 from being damaged. The protective film 202 may include a material film having lower thermal conductivity than the substrate 201 and may be a single film or a laminated film using a material film having lower thermal conductivity than the substrate 201. [ In one example, in the case where the substrate 201 includes a silicon-containing material, the protective film 202 may include a silicon-containing insulating film and a metal-containing insulating film. The silicon-containing insulating film may include a silicon oxide film (SiO ₂ ), and the metal-containing insulating film may include a zirconium oxide film (ZrO ₂ ).

The image sensor according to the embodiment may include a color filter 205 formed on the back-side of the substrate 201 and a microlens 206 formed on the color filter 205.

The image sensor having the above-described structure includes the element isolation structure 230 in which the first element isolation 210 and the second element isolation 220 are vertically overlapped with each other so that the physical and electrical crosstalk between adjacent pixels can be effectively .

In addition, since the element isolation structure 230 has a refractive index smaller than that of the substrate 201 including the photoelectric conversion region PD, it is possible to more effectively prevent physical crosstalk between adjacent pixels.

In addition, the second isolation 220 can more effectively prevent electrical crosstalk because the impurity doping concentration of the second impurity region 222 surrounding the first impurity region 221 is larger.

In addition, the second device isolation 220 includes the third impurity region 223 extended to the interface between the first device isolation 210 and the substrate 201, thereby effectively preventing occurrence of dark current.

FIGS. 6A to 6E are cross-sectional views illustrating a method of manufacturing an image sensor according to a second embodiment of the present invention, and illustrate an example of the method of manufacturing the image sensor shown in FIG. 5A.

As shown in Fig. 6A, a substrate 31 on which a plurality of pixels are defined is prepared. The substrate 31 may comprise a semiconductor substrate. The semiconductor substrate may be in a single crystal state, and may include a silicon-containing material. That is, the substrate 31 may comprise a single crystal silicon containing material.

Next, a photoelectric conversion region PD is formed in the substrate 31 so as to correspond to each of the pixels. The photoelectric conversion region PD may include a plurality of vertically overlapping photoelectric conversion portions, and each of the photoelectric conversion portions may be a photodiode including an N-type impurity region and a P-type impurity region. The photodiode can be formed through an impurity ion implantation process.

Next, a protective film 32 is formed on the substrate 31 including the photoelectric conversion region PD. The protective film 32 may be formed of a material film having lower thermal conductivity than the substrate 31 and may be formed of a single film or a laminated film using a material film having lower thermal conductivity than the substrate 31. [ For example, in the case where the substrate 31 includes a silicon-containing material, the protective film 32 may be formed of a silicon-containing insulating film and / or a metal-containing insulating film. The silicon-containing insulating film may include a silicon oxide film (SiO ₂ ), and the metal-containing insulating film may include a zirconium oxide film (ZrO ₂ ).

Next, an interlayer insulating film 33 including a signal generating circuit is formed on the protective film 32. Then, The interlayer insulating film 33 may be any one selected from the group consisting of an oxide film, a nitride film, and a nitrided oxide film, and may have a multilayer structure. The signal generating circuit generates (or outputs) an electrical signal corresponding to the charge generated in the photoelectric conversion region PD. Specifically, the signal generation circuit may include a plurality of transistors and a multi-layered metal wiring 34. [ The plurality of transistors may include a transfer transistor Tx, a reset transistor Rx, a selection transistor Sx, and an access transistor Ax. The multilayer metal wiring 34 can be electrically connected to the plurality of transistors and the plurality of metal wirings 34 through a plurality of contact plugs (not shown).

A mask pattern (not shown) is formed on the back-side of the substrate 31 after the substrate 31 on which the signal generating circuit is formed is inverted as shown in Fig. 6B. The mask pattern may have a shape that opens only a region where the element isolation structure is to be formed.

Next, the substrate 31 is etched with a mask pattern (not shown) as an etching barrier to form a trench 35 for first element isolation. The trench 35 may have vertical sidewalls or inclined sidewalls to control the path of incident light. The etching process for forming the trenches 35 can be performed by dry etching.

Next, pre-amorphization is performed in which impurities are ion-implanted into the rear surface of the substrate 31 on which the trench 35 is formed with a mask pattern (not shown) as an ion implantation barrier. The pre-amorphization can proceed a plurality of times while changing the impurity ion implantation angle. When the substrate 31 is a silicon-containing material, impurities such as germanium (Ge), silicon (Si), carbon (C) and the like can be used as the impurity for pre-amorphization. The amorphous region 36 can be formed on the substrate 31 through the linear amorphization. The amorphous region 36 can be formed in a pillar shape in which the upper surface and the lower surface are in contact with the bottom surface of the trench 35 and the front surface of the substrate 31, respectively. In addition, the amorphous region 36 may be formed so as to have an extended shape so that a part of the amorphous region 36 is in contact with the side wall of the trench 35. That is, the amorphous region 36 can also be formed on the sidewall substrate 31 of the trench 35.

The linear amorphization is for forming an amorphous region 36 having a lower melting temperature than the substrate 31 in the single crystal state. Specifically, the amorphous region 36 through the linear amorphization can have a lower melting temperature than the substrate 31 in the single crystal state. For example, amorphous silicon has a melting temperature as low as about 200 캜 lower than monocrystalline silicon.

Though not shown in the drawing, the thickness of the substrate 31 can be reduced by performing a thinning process on the back-side of the substrate 31 after the signal generating circuit is formed. This is to increase the light receiving efficiency by reducing the distance of incident light incident on the photoelectric conversion region PD. The thinning process can be performed by backgrinding and polishing.

6C, a mask pattern (not shown) is introduced into the amorphous region 36 as an ion implantation barrier so as to have a refractive index smaller than that of the substrate 31 including the photoelectric conversion region PD, and at the same time, ) Is implanted by ion implantation. Hereinafter, the denomination of the impurity-doped amorphous region 36 is denoted by "37".

The impurity which can induce a refractive index smaller than that of the substrate 31 including the photoelectric conversion region PD may include a metal and the impurity capable of forming a potential barrier with respect to the photoelectric conversion region PD may be an adjacent photoelectric conversion May mean an impurity having a conductive type complementary to the conductive type of the region PD. For example, when the conductivity type of the photoelectric conversion region PD having the side wall facing the amorphous region 37 is N-type, the P-type metal can be used as an impurity in the ion implantation process.

As shown in FIG. 6D, the annealing process for activating the impurities injected into the amorphous region 37 and recrystallizing the amorphous region 37 is performed. The annealing is selectively performed only on the amorphous region 37 in order to prevent the deterioration of the characteristics due to the diffusion of the impurities implanted in the annealing process and to reduce the thermal burden imposed on the preformed structure. For this purpose, the annealing process can proceed to a laser anneal capable of local annealing.

The annealing process using laser annealing is performed by irradiating the laser to the amorphous region 37 doped with impurities for a predetermined time to melt the amorphous region 37 having a relatively low melting temperature with respect to the single crystal substrate 31 , The molten amorphous region 37 is solidified and recrystallized from the point of time when the laser irradiation is stopped, and at the same time, the injected impurity is activated. At this time, even if the laser is irradiated on the substrate 31 due to the difference in melting temperature between the single crystal substrate 31 and the amorphous region 37, the substrate 31 is not melted. That is, selective melting is possible by forming the amorphous region 37 (see FIG. 10).

Thereby, the first impurity region 38, the second impurity region 39 formed along the edge of the first impurity region 38 and having an impurity doping concentration larger than that of the first impurity region 38, and the second impurity region 39 formed on the side wall of the trench 35 The second isolation 41 including the third impurity region 40 formed can be formed. It is possible to recrystallize the amorphous region 37 by melting the amorphous region 37 doped with impurities during the annealing process and to improve the activation rate of the doped impurities and to accumulate impurities injected into the boundary region during the recrystallization process it is possible to easily form the second element isolation 41 including the first impurity region 38 to the third impurity region 40 (see FIG. 9). In addition, dangling bonds, defects, and the like on the surface of the trench 35 are removed by the third impurity region 40, so that occurrence of a dark current can be effectively prevented.

On the other hand, in the annealing process, the protective film 32 including a material film having lower thermal conductivity than the substrate 31 can prevent damage to the preformed signal generating circuit, in particular, the multilayer metal wiring 34.

As shown in FIG. 6E, an insulating film 42 is formed to cover the trench 35. The insulating film 42 may be formed through a series of processes in which the insulating film 42 is formed on the substrate 31 so as to cover the trench 35 and then the planarization process is performed until the surface of the substrate 31 is exposed. The insulating film 42 may be any one single film selected from the group consisting of an oxide film, a nitride film, and a nitrided oxide film having a refractive index lower than that of the substrate 31 corresponding to each pixel, or two or more laminated laminated films.

Thereby, the first device isolation 43 including the insulating film 42 for tapping the trench 35 formed in the substrate 31 can be formed. Further, the device isolation structure 44 including the first device isolation 43 and the second device isolation 41 vertically overlapping can be formed.

Next, although not shown in the drawing, an image sensor can be completed using a known manufacturing technique. For example, a color filter and a microlens may be sequentially formed on the rear surface of the substrate 31 to complete the image sensor.

The image sensor formed through the above-described manufacturing method has the element isolation structure 44 in which the first element isolation 43 and the second element isolation 41 vertically overlap with each other so that the physical and electrical crosstalk between adjacent pixels Can be effectively prevented.

In addition, since the element isolation structure 44 has a refractive index smaller than that of the substrate 31 including the photoelectric conversion region PD, it is possible to more effectively prevent physical crosstalk between adjacent pixels.

In addition, the second device isolation 41 can more effectively prevent electrical crosstalk because the impurity doping concentration of the second impurity region 39 surrounding the first impurity region 38 is larger.

In addition, the occurrence of dark current can be effectively prevented by the third impurity region 40 of the second element isolation 41.

In addition, the annealing process for selectively melting the amorphous region 37 having a lower melting temperature than that of the substrate 31 in the single crystal state prevents the deterioration of the characteristics due to the diffusion of the implanted impurities, The thermal burden can be reduced.

Figs. 7A and 7B are cross-sectional views along the A-A 'perforation line shown in Fig. 2. Fig. FIG. 7A is a cross-sectional view illustrating an image sensor according to a third embodiment of the present invention, and FIG. 7B is a cross-sectional view illustrating a modified example of the image sensor according to the third embodiment of the present invention.

2, 7A and 7B, an image sensor according to an embodiment may include a plurality of device isolation structures 330 separated by a device isolation structure 330 including a first device isolation 310 and a second device isolation 320, (Not shown) formed on the substrate 301 in correspondence with the respective pixels separated by the device isolation structure 330 and the substrate 301 having the pixels 301 of the pixel 301 and the protruded surface 301A corresponding to the respective pixels, And may include a photoelectric conversion region PD.

The substrate 301 may include a semiconductor substrate. The semiconductor substrate may be in a single crystal state, and may include a silicon-containing material. That is, the substrate 301 may comprise a single crystal silicon containing material. The protruded surface 301A serves to improve the focusing ability with respect to incident light and can be formed on the back-side of the substrate 301 on which the incident light enters. The protruding surface 301A may have curvature for effective focusing of the incident light. For example, the protruded surface 301A having a curvature may have a convex shape protruding over the back-side of the substrate 301. [

The photoelectric conversion region PD may include a plurality of vertically overlapping photoelectric conversion units, and each of the photoelectric conversion units may be a photodiode including an N-type impurity region and a P-type impurity region. The photoelectric conversion region PD and the element isolation structure 330 may have a predetermined spacing.

The first device isolation 310 may include an insulating film 312 for tapping the trench 311 formed in the substrate 301. Trench 311 may have vertical sidewalls, or may have sloped sidewalls. The shape of the sidewalls of the trench 311 can be adjusted to control the path of the incident light. The insulating film 312 may be any one single film selected from the group consisting of an oxide film having a refractive index lower than that of the substrate 301 including the photoelectric conversion region PD, a nitride film, and a nitride oxide film, or two or more laminated laminated films. In one example, when the substrate 301 includes a silicon-containing material, the insulating film 312 may include a silicon oxynitride film.

The second element isolation 320 may have an impurity region that has a refractive index smaller than that of the substrate 301 including the photoelectric conversion region PD and functions as a potential barrier for the photoelectric conversion region PD. Here, an impurity region having a refractive index smaller than that of the substrate 301 including the photoelectric conversion region PD is formed by doping or alloying the impurity which induces a refractive index smaller than that of the substrate 301, . ≪ / RTI > The impurity region serving as a potential barrier with respect to the photoelectric conversion region PD may have a conductivity type complementary to that of the photoelectric conversion region PD facing the side wall. More specifically, when the conductivity type of the photoelectric conversion region PD facing the side wall of each other is N-type, the conductivity type of the impurity region may be P-type. That is, the impurity region may be formed by doping the substrate 301 with a P-type impurity, and the P-type impurity may include a P-type metal. For example, when the substrate 301 includes a silicon-containing material, silver (Ag), cobalt (Co), iron (Fe) or the like may be used as the P type metal, And has a lower refractive index than silicon. Conversely, when the conductivity type of the photoelectric conversion region PD facing the side wall of each other is P type, the conductivity type of the impurity region may be N type, and the N type impurity may include N type metal. For example, when the substrate 301 includes a silicon-containing material, aluminum (Al), titanium (Ti) or the like may be used as the N-type metal, and the N-type metal combined with the silicon may have a refractive index lower than that of silicon .

The impurity region constituting the second element isolation 320 may be formed through an impurity ion implantation process and an anneal process. Depending on the characteristics of the annealing process, the pile up of the impurity implanted along the edge of the impurity region ) Shape (see Fig. 9). Specifically, the second isolation 320 includes a first impurity region 321 and a second impurity region 321 formed along the edge of the first impurity region 321 and having an impurity doping concentration larger than that of the first impurity region 321 322) (see FIG. 7A). The second isolation 320 includes a third impurity region 323 formed between the substrate 301 and the first device isolation 310 in addition to the first impurity region 321 and the second impurity region 322 (See FIG. 7B). Since the impurity doping concentration of the second impurity region 322 is larger than that of the first impurity region 321, the potential barrier at the impurity region interface can be increased to more effectively prevent electrical crosstalk. The third impurity region 323 formed between the substrate 301 and the first device isolation 310 is formed by removing dangling bonds and defects at the interface between the first device isolation 310 and the substrate 301, Thereby preventing the occurrence of the problem.

In addition, the first device isolation 310 and the second device isolation 320 of the device isolation structure 330 according to the embodiment may have a vertically overlapping structure. Specifically, the second device isolation 320 may have a structure in which the second device isolation 320 is stacked on the first device isolation 310 with reference to the back-side of the substrate 301. The device isolation structure 330 having the structure in which the second device isolation 320 is stacked on the first device isolation 310 with respect to the back-side of the substrate 301 can effectively prevent occurrence of dark current. The element isolation structure 330 may have a depth greater than the depth of the photoelectric conversion region PD with respect to the front side of the substrate 301. This is to improve separation characteristics between adjacent pixels and to prevent crosstalk more effectively. For example, the element isolation structure 330 may have a shape penetrating through the substrate 301.

The image sensor according to the embodiment includes an interlayer insulating film 303 formed on the front surface of a substrate 301, a signal generating circuit formed inside the interlayer insulating film 303, a protective film formed between the substrate 301 and the interlayer insulating film 303 302). The signal generating circuit generates (or outputs) an electrical signal corresponding to the charge generated in the photoelectric conversion region PD. Specifically, the signal generation circuit may include a plurality of transistors and a multi-layered metal wiring 304. The plurality of transistors may include a transfer transistor Tx, a reset transistor Rx, a selection transistor Sx, and an access transistor Ax. The multi-layered metal wiring 304 can be electrically connected to the plurality of transistors and the plurality of metal wiring 304 through a plurality of contact plugs (not shown). The protective film 302 serves to prevent damage to the inter-process signal generating circuit, particularly, the multi-layered metal wiring 304. The protective film 302 may include a material film having lower thermal conductivity than the substrate 301 and may be a single film or a laminated film using a material film having lower thermal conductivity than the substrate 301. In one example, in the case where the substrate 301 includes a silicon-containing material, the protective film 302 may include a silicon-containing insulating film 312 and a metal-containing insulating film 312. The silicon-containing insulating film 312 may include a silicon oxide film (SiO ₂ ), and the metal-containing insulating film 312 may include a zirconium oxide film (ZrO ₂ ).

The image sensor according to the embodiment includes a planarization film 307 formed on the back side of the substrate 301, a color filter 305 formed on the planarization film 307, And a lens 306 as shown in FIG. The planarizing film 307 serves to remove the stepped portion by the protruded surface 301A.

The image sensor having the above-described structure includes the element isolation structure 330 in which the first element isolation 310 and the second element isolation 320 are vertically overlapped to effectively prevent physical and electrical crosstalk between adjacent pixels can do.

In addition, since the element isolation structure 330 has a refractive index smaller than that of the substrate 301 including the photoelectric conversion region PD, it is possible to more effectively prevent physical crosstalk between adjacent pixels.

In addition, the second isolation 320 can more effectively prevent electrical crosstalk because the impurity doping concentration of the second impurity region 322 surrounding the first impurity region 321 is larger.

In addition, the second element isolation 320 includes the third impurity region 323 extended to the interface between the first element isolation 310 and the substrate 301, thereby effectively preventing occurrence of dark current.

Further, by providing the surface 301A protruding from the substrate 301, focusing on incident light can be improved.

8A to 8G are cross-sectional views illustrating a method of manufacturing an image sensor according to a third embodiment of the present invention, and are views for explaining an example of a method of manufacturing the image sensor shown in FIG. 7A.

As shown in Fig. 8A, a substrate 51 on which a plurality of pixels are defined is prepared. The substrate 51 may comprise a semiconductor substrate. The semiconductor substrate may be in a single crystal state, and may include a silicon-containing material. That is, the substrate 51 may include a single crystal silicon-containing material.

Next, a photoelectric conversion region PD is formed in the substrate 51 so as to correspond to each pixel. The photoelectric conversion region PD may include a plurality of vertically overlapping photoelectric conversion portions, and each of the photoelectric conversion portions may be a photodiode including an N-type impurity region and a P-type impurity region. The photodiode can be formed through an impurity ion implantation process.

Next, the protective film 52 is formed on the substrate 51 including the photoelectric conversion region PD. The protective film 52 may be formed of a material film having lower thermal conductivity than the substrate 51 and may be formed of a single film or a laminated film using a material film having lower thermal conductivity than the substrate 51. For example, in the case where the substrate 51 includes a silicon-containing material, the protective film 52 may be formed of a silicon-containing insulating film and / or a metal-containing insulating film. The silicon-containing insulating film may include a silicon oxide film (SiO ₂ ), and the metal-containing insulating film may include a zirconium oxide film (ZrO ₂ ).

Next, an interlayer insulating film 53 including a signal generating circuit is formed on the protective film 52. Then, The interlayer insulating film 53 may be any one selected from the group consisting of an oxide film, a nitride film, and a nitrided oxide film, and may have a multilayer structure. The signal generating circuit generates (or outputs) an electrical signal corresponding to the charge generated in the photoelectric conversion region PD. Specifically, the signal generation circuit may include a plurality of transistors and a multi-layered metal wiring 54. The plurality of transistors may include a transfer transistor Tx, a reset transistor Rx, a selection transistor Sx, and an access transistor Ax. The multilayered metal wiring 54 may be electrically connected to the plurality of transistors and the plurality of metal wirings 54 through a plurality of contact plugs (not shown).

A mask pattern (not shown) is formed on the back-side of the substrate 51 after the substrate 51 on which the signal generating circuit is formed is inverted as shown in Fig. 8B. The mask pattern may have a shape that opens only a region where the element isolation structure is to be formed.

Next, the substrate 51 is etched using a mask pattern (not shown) as an etch barrier to form a trench 55 for first element isolation. The trench 55 may have a vertical sidewall or a sloped sidewall to control the path of incident light. The etching process for forming the trenches 55 can be performed by dry etching.

Though not shown in the drawing, the thickness of the substrate 51 can be reduced by performing a thinning process on the back-side of the substrate 51 after forming the signal generating circuit. This is to increase the light receiving efficiency by reducing the distance of incident light incident on the photoelectric conversion region PD. The thinning process can be performed by backgrinding and polishing.

A first annealing process is performed to form the surface 51A on which the substrate 51 protrudes on the back surface of the substrate 51 corresponding to the photoelectric conversion region PD as shown in FIG. The primary annealing process may proceed to a local annealable laser anneal to form a selectively protruding surface 51A on the backside of the substrate 51 corresponding to the photoelectric conversion region PD. The protruded surface 51A is for improving the focusing on the incident light and can be formed through a lattice movement occurring in the first annealing process (see FIG. 11).

On the other hand, the damage (or defect) generated on the surface of the trench 55 in the trench 55 forming process can be healed by the first annealing process. Therefore, the occurrence of the dark current can be prevented through the primary annealing process. It is also possible to prevent damage to the preformed signal generating circuit, in particular, the multilayer metal wiring 54, by the protective film 52 including the material film having lower thermal conductivity than the substrate 51 in the first annealing step.

8 (d), a mask pattern (not shown) for opening the trench 55 is subjected to pre-amorphization in which impurities are ion-implanted into the rear surface of the substrate 51 on which the trench 55 is formed, . When the substrate 51 is a silicon-containing material, impurities such as germanium (Ge), silicon (Si), carbon (C) and the like can be used as the impurity for pre-amorphization. The amorphous region 56 can be formed on the substrate 51 through the line amorphization. The amorphous region 56 can be formed in a pillar shape in which the upper surface and the lower surface are in contact with the bottom surface of the trench 55 and the front surface of the substrate 51, respectively.

The pre-amorphization is intended to form an amorphous region 56 having a lower melting temperature than the substrate 51 in the single crystal state. Specifically, the amorphous region 56 through the linear amorphization can have a lower melting temperature than the single crystal substrate 51. For example, amorphous silicon has a melting temperature as low as about 200 캜 lower than monocrystalline silicon.

8E, a mask pattern (not shown) is introduced into the amorphous region 56 as an ion implantation barrier so as to have a smaller refractive index than the substrate 51 including the photoelectric conversion region PD, and at the same time, ) Is implanted by ion implantation. Hereinafter, the denomination of the impurity-doped amorphous region 56 is denoted by "57".

The impurity which can induce a refractive index smaller than that of the substrate 51 including the photoelectric conversion region PD may include a metal and the impurity capable of forming a potential barrier with respect to the photoelectric conversion region PD may be an adjacent photoelectric conversion May mean an impurity having a conductive type complementary to the conductive type of the region PD. For example, when the conductivity type of the photoelectric conversion region PD having the side wall facing the amorphous region 57 is N-type, a P-type metal can be used as an impurity in the ion implantation process.

As shown in FIG. 8F, a second annealing process is performed to activate the doped impurities and recrystallize the amorphous regions 57. The annealing is selectively performed only on the amorphous region 57 in order to prevent the deterioration of characteristics due to the diffusion of impurities implanted in the second annealing process and to reduce the thermal burden imposed on the preformed structure. For this purpose, the secondary annealing process can proceed to a laser anneal capable of local annealing.

The second annealing process using the laser annealing is performed by irradiating the laser to the amorphous region 57 doped with impurities for a predetermined time to melt the amorphous region 57 having a relatively low melting temperature with respect to the single crystal substrate 51, ), And the molten amorphous region 57 is recrystallized from the point of time when the laser irradiation is stopped, and at the same time, the injected impurity is activated. At this time, the substrate 51 is not melted even if the laser is irradiated on the substrate 51 due to the difference in melting temperature between the single crystal substrate 51 and the amorphous region 57. That is, selective melting can be performed as the amorphous region 57 is formed (see FIG. 10).

The first impurity region 58 and the second impurity region 59 including the second impurity region 59 formed along the edge of the first impurity region 58 and having an impurity doping concentration larger than that of the first impurity region 58, (60) can be formed. Quality crystallization can be achieved by melting the amorphous region 57 doped with impurities in the second annealing process and the activation rate of the impurities implanted can be improved and impurities injected into the boundary region during the recrystallization process can be accumulated The first impurity region 58 and the second impurity region 59 can be simultaneously formed (see FIG. 9).

On the other hand, it is possible to prevent damage to the preformed signal generating circuit, particularly, the multilayer metal wiring 54 by the protective film 52 including the material film having lower thermal conductivity than the substrate 51 in the second annealing process.

As shown in Fig. 8G, an insulating film 61 is formed so as to cover the trench 55. As shown in Fig. The insulating film 61 is formed by forming an insulating film 61 on the substrate 51 so as to cover the trench 55 and then performing a planarization process until the surface of the substrate 51 is exposed, 61) may be formed through a series of process steps. The insulating film 61 may be any one single film selected from the group consisting of an oxide film, a nitride film, and a nitrided oxide film having a refractive index lower than that of the substrate 51 corresponding to each of the pixels, or two or more laminated laminated films.

Thereby, the first device isolation 62 including the insulating film 61 for tapping the trench 55 formed in the substrate 51 can be formed. Further, the device isolation structure 63 including the first device isolation 62 and the second device isolation 60 vertically overlapping can be formed.

Next, although not shown in the drawing, an image sensor can be completed using a known manufacturing technique. For example, a planarizing film, a color filter, and a microlens may be sequentially formed on the rear surface of the substrate 51 to complete the image sensor.

The image sensor formed through the above-described manufacturing method has the element isolation structure 63 in which the first element isolation 62 and the second element isolation 60 vertically overlap each other, so that the physical and electrical crosstalk between adjacent pixels Can be effectively prevented.

In addition, since the element isolation structure 63 has a refractive index smaller than that of the substrate 51 including the photoelectric conversion region PD, it is possible to more effectively prevent physical crosstalk between adjacent pixels.

Further, the second element isolation 60 can more effectively prevent electrical crosstalk because the impurity doping concentration of the second impurity region 59 surrounding the first impurity region 58 is larger.

In addition, by forming the protruded surface 51A through the primary annealing process, focusing on incident light can be improved, and occurrence of dark current can be prevented.

In addition, the secondary annealing process for selectively melting the amorphous region 57 having a lower melting temperature than that of the substrate 51 in the single crystal state prevents characteristic deterioration due to the diffusion of the implanted impurities, The thermal load applied can be reduced.

9 is a graph showing impurity doping concentration of the impurity region formed through laser annealing including selective melting.

Referring to FIG. 9, it can be seen that the impurity region activated by laser annealing including selective melting, that is, the second element isolation, piles up the impurities injected into the boundary region. That is, it can be seen that the second impurity region having the impurity doping concentration larger than that of the first impurity region and the first impurity region is formed by laser annealing including selective melting.

In addition, the first impurity region maintains a relatively uniform impurity doping concentration depending on the depth, and the depth of the second element isolation can be controlled according to the laser irradiation energy.

10 is a graph showing the melting of silicon having different crystal structures depending on laser irradiation energy.

Referring to FIG. 10, when the amorphous silicon and the single crystal silicon are irradiated with a laser of the same energy, it can be confirmed that selective melting is possible due to the difference in crystal structure. That is, the amorphous silicon and the single crystal silicon differ from each other in melting temperature due to the difference in the crystal structure thereof, and only the amorphous silicon can be selectively melted by using this difference.

11 is an image showing lattice movement according to laser annealing.

Referring to FIG. 11, it can be seen that as the laser irradiation energy increases, a quadrangle (corresponding to the trench in the third embodiment) is deformed into a rounded shape. That is, the silicon lattice is moved and deformed by the laser annealing, and the protruded surface can be formed by using the silicon lattice.

12 is a block diagram showing the configuration of an image sensor according to an embodiment of the present invention.

12, the CMOS image sensor 2100 may include an active pixel sensor array (APS array) 2110, a controller 2130, a row driver 2120, and a pixel signal processor 2140. The active pixel sensor array 2110 may include an image sensor according to the first to third embodiments of the present invention. More specifically, the active pixel sensor array 2110 includes a first element isolation region including an insulating film that fills a trench formed in a substrate, a first impurity region formed on the substrate, and a second impurity region formed along the edge of the first impurity region, A second element isolation structure including a second impurity region having a large impurity doping concentration, and a photoelectric conversion region formed on the substrate corresponding to a plurality of pixels separated by the element isolation structure. In addition, the second element isolation may further include a third impurity region formed between the substrate and the first element isolation. The semiconductor device may further include a protective film formed on the entire surface of the substrate, an interlayer insulating film formed on the protective film and including a metal wiring, and a surface protruding from the rear surface of the substrate corresponding to the photoelectric conversion region. The electrical signal converted in the photoelectric conversion region is provided to the pixel signal processing unit 2140 through the vertical signal line. The pixel sensors in the active pixel sensor array 2110 are read out one at a time on a row basis. Thus, the pixels in one row of active pixel sensor array 2110 are all simultaneously activated by the row select signal, which is the output of row driver 2120.

Also, each pixel in the selected row provides a signal corresponding to the received light to the output line of the corresponding column. Within the active pixel sensor array (APS) 1210, each column has a select line, and the pixel cells of each column are selectively output in response to the column select signal. The rows within the active pixel sensor array (APS) 2110 are activated in response to the output signal of the row driver 2120.

The controller 2130 controls the row driver 2120 and the pixel signal processing unit 2140 for proper processing of the pixel signal output from the active pixel sensor array 2110. The pixel signal processing unit 2140 includes a correlated double sampler (CDS) 2142, an analog-to-digital converter (ADC) 2144 and a buffer 2146.

The correlated dual sampler (CDS) 2142 receives and samples and holds the electrical signal generated by the active pixel sensor array 2110 through the vertical signal line. That is, the noise level and the signal level caused by the generated electrical signal are sampled double, and the difference level corresponding to the difference between the noise level and the signal level is output. A ramp signal generated from a ramp signal generator (Ramp Gen .: 2148) may be input and compared with each other, and the comparison result may be output to an output terminal. The ramp signal generator (Ramp Gen .: 2148) may operate based on the control signal generated by the controller 2130.

An analog-to-digital converter (ADC) 2144 converts an analog signal corresponding to the difference level into a digital signal. The buffer 2146 includes a column memory block (not shown) and a sense amplifier (not shown), and the column memory block (not shown) may include a plurality of memories (not shown).

A buffer (Buffer) 2146 latches the digital signal, and the latched signal is sequentially output to an image processor (not shown) in accordance with a decoding result in a column decoder (not shown).

The CMOS image sensor 2100 of FIG. 12 may further include an image processor (not shown) and may be implemented as one semiconductor chip. An image processor (not shown) performs appropriate image processing on the digitized pixel signals to output image data. The CMOS image sensor 2100 senses an object imaged through a lens under the control of an image processor (not shown), and the image processor (not shown) is sensed by the image sensor 2100 and output And output the image to the display unit (not shown). At this time, the display unit (not shown) includes all devices capable of outputting images. For example, the display unit (not shown) may include a computer, a mobile phone, and other video output terminals. The CMOS image sensor 2100 according to the embodiment of the present invention shown in FIG. 12 may include an image sensor according to the first to third embodiments of the present invention. Therefore, it is possible to output image data that is not damaged by the crosstalk between the adjacent pixels and the dark current.

13 is a block diagram illustrating a system including an image sensor in accordance with an embodiment of the present invention.

Here, the system 2200 of FIG. 13 may be a computer system, a camera system, a scanner, a vehicle navigation, a video phone, an expense system, or a motion detection system that require image data.

13, the system 2200 includes a central processing unit (CPU) 2210 or a processor 2210, a nonvolatile memory 2220, an image sensor 2230, an input / output device (I / O) 2240 ) And a RAM (Random Access Memory) 2250.

A central processing unit (CPU) 2210 communicates with an input / output device (I / O) 2240 via a bus 2260.

The image sensor 2230 communicates with a central processing unit (CPU) 2210 via a bus 2260. The RAM 2250 and the nonvolatile memory 2220 also communicate with the central processing unit (CPU) 2210 via the bus 2260. [ The image sensor 2230 may be an independent semiconductor chip or may be combined with the central processing unit 2210 to form one semiconductor chip.

The image sensor 2230 included in the system of FIG. 13 may include an image sensor according to the first to third embodiments of the present invention. Therefore, it is possible to output image data that is not damaged by the crosstalk between the adjacent pixels and the dark current.

In the embodiments of the present invention, the device isolation structure according to the technical idea of the present invention is applied to the image sensor. However, the device isolation structure according to the technical idea of the present invention is not limited to the device isolation It is applicable to all semiconductor devices requiring a structure.

The technical idea of the present invention has been specifically described according to the above preferred embodiments, but it should be noted that the above embodiments are intended to be illustrative and not restrictive. In addition, it will be understood by those of ordinary skill in the art that various embodiments within the scope of the technical idea of the present invention are possible.

101: substrate 102: protective film
103: interlayer insulating film 104: metal wiring
105: Color filter 106: Micro lens
110: first element isolation 111: trench
112: Insulating film 120: Second element isolation
121: first impurity region 122: second impurity region
130: Element isolation structure

Claims (20)

And a second impurity region formed along the edge of the first impurity region and having a second impurity concentration higher than an impurity doping concentration of the first impurity region, A device isolation structure in which a second device isolation including a region is stacked; And
A photoelectric conversion region formed on the substrate corresponding to a plurality of pixels separated by the device isolation structure,
.
The method according to claim 1,
Wherein the second element isolation further comprises a third impurity region formed between the substrate and the first element isolation.
The method according to claim 1,
Wherein the device isolation structure has a smaller refractive index than the substrate including the photoelectric conversion region.
The method of claim 3,
And the second device isolation acts as a potential barrier for the photoelectric conversion region.
5. The method of claim 4,
Wherein the second element isolation includes a metal-doped impurity region having a conductivity type complementary to the conductivity type of the photoelectric conversion region.
The method according to claim 1,
Wherein the second element isolation is laminated on the first element isolation or the first element isolation is laminated on the second element isolation.
The method according to claim 1,
Wherein a depth of the device isolation structure is larger than a depth of the photoelectric conversion region.
The method according to claim 1,
Wherein the device isolation structure penetrates the substrate.
The method according to claim 1,
A protective film formed on the front surface of the substrate;
An interlayer insulating film formed on the protective film and including a metal wiring; And
A surface protruding from the rear surface of the substrate corresponding to the photoelectric conversion region
Further comprising an image sensor.
10. The method of claim 9,
Wherein the protective film comprises a material film having a lower thermal conductivity than the substrate.
Forming a photoelectric conversion region on a substrate corresponding to the plurality of pixels;
Forming a trench in a substrate between the photoelectric conversion regions;
Forming an amorphous region in the substrate below the trench, the amorphous region having a lower melting temperature than the substrate;
Implanting impurities into the amorphous region; And
Melting the amorphous region to activate the implanted impurities and annealing to recrystallize the impurities
≪ / RTI >
12. The method of claim 11,
Further comprising the step of forming an insulating film that will glue the trench before or after the amorphous region is formed.
13. The method of claim 12,
Wherein the insulating film comprises a material film having a lower refractive index than the substrate including the photoelectric conversion region.
12. The method of claim 11,
And advancing the anneal after forming the trench to protrude the substrate surface corresponding to the photoelectric conversion region.
12. The method of claim 11,
Wherein the annealing comprises laser annealing.
16. The method of claim 15,
The method of claim 1,
Irradiating the laser for a predetermined time to melt the amorphous region; And
Blocking the laser to solidify the molten amorphous region
Wherein the device isolation structure is formed on the substrate.
12. The method of claim 11,
Wherein the impurity implanted into the amorphous region includes a material capable of inducing a lower refractive index than the substrate including the photoelectric conversion region and forming a potential barrier with respect to the photoelectric conversion region.
18. The method of claim 17,
Wherein the impurity includes a metal having a conductivity type complementary to the conductivity type of the photoelectric conversion region.
12. The method of claim 11,
After forming the photoelectric conversion region
Forming a protective film on the substrate; And
Forming an interlayer insulating film including a metal wiring on the protective film
≪ / RTI >
20. The method of claim 19,
Wherein the protective film comprises a material film having lower thermal conductivity than the substrate.

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