KR101194742B1 - Method for forming semiconductor device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a semiconductor device. In the process of forming a device isolation layer using a conventional STI process and a process of forming a fin active region by etching the device isolation layer, the process steps are complicated and the area of the fin active region is complicated. And in order to solve a problem that it is difficult to ensure uniformity, after forming the first oxide layer, the nitride layer and the second oxide layer on the silicon substrate, which can act as device isolation layers, they are patterned to define the active region and then exposed. By removing the second oxide layer after forming the epitaxial growth layer on the formed silicon substrate, it is possible to improve the area securing and uniformity of the fin type active region while performing a simpler process than the conventional fin type active region forming process. The invention relates to.

Description

Method of forming a semiconductor device {METHOD FOR FORMING SEMICONDUCTOR DEVICE}

1 is a plan view showing a method of forming a semiconductor device according to the prior art.

2A to 2E are cross-sectional views illustrating a method of forming a semiconductor device according to the prior art.

3 is a cross-sectional view showing a method of forming a semiconductor device according to the prior art.

4 is a plan view showing a method of forming a semiconductor device according to the present invention.

5A to 5C are cross-sectional views illustrating a method of forming a semiconductor device in accordance with the present invention.

6 is a cross-sectional view illustrating a bit line contact according to the present invention.

7 is a cross-sectional view illustrating a storage node contact in accordance with the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a semiconductor device. In the process of forming a device isolation layer using a conventional STI process and a process of forming a fin active region by etching the device isolation layer, the process steps are complicated and the area of the fin active region is complicated. And in order to solve a problem that it is difficult to ensure uniformity, after forming the first oxide layer, the nitride layer and the second oxide layer on the silicon substrate, which can act as device isolation layers, they are patterned to define the active region and then exposed. By removing the second oxide layer after forming the epitaxial growth layer on the formed silicon substrate, it is possible to improve the area securing and uniformity of the fin type active region while performing a simpler process than the conventional fin type active region forming process. The invention relates to.

As semiconductor devices are highly integrated, process margins for forming active regions and device isolation layers are reduced. In addition, as the line width of the gate narrows, the electrical characteristics of the semiconductor device are degraded due to the decrease in the channel length, and the short channel effect occurs. In order to overcome this, a transistor having a structure such as a fin type gate has been developed. Fin-type gate is a technology that can increase the drive area of the gate and improve the electrical characteristics by increasing the contact area between the active region and the gate.

1 is a plan view illustrating a method of forming a semiconductor device according to the prior art.

Referring to FIG. 1, a device isolation layer 60 defining an active region 50 having a bar shape is formed on the silicon substrate 10, and a gate 90 is formed thereon. In this case, in order to increase the contact area between the active region 50 and the gate 90, the device isolation layer 60 under the gate 90 is etched to a predetermined depth so that the active region 50 under the gate 90 has a fin shape. To be

2A to 2E are cross-sectional views illustrating a method of forming a semiconductor device according to the prior art, and are views taken along a line BB ′ of FIG. 1.

Referring to FIG. 2A, after the pad oxide layer and the pad nitride layer are formed on the silicon substrate 10, the pad oxide layer pattern 20 and the pad nitride layer pattern 30 are formed by an etching process using the photoresist pattern 40 which blocks the active region. To form.

Referring to FIG. 2B, after removing the photoresist pattern 40, the silicon substrate 10 is etched with a pad nitride film pattern 30 as a mask to form a device isolation trench. Next, a device isolation film 60 is formed by filling a device isolation trench with an oxide film using a high density plasma (HDP) process. Here, the silicon substrate 10 defined by the device isolation layer 60 becomes the active region 50.

Referring to FIG. 2C, the pad nitride layer pattern 30 and the pad oxide layer pattern 20 are removed. In this case, the pad nitride layer pattern 30 is removed using hot phosphoric acid. In this process, the interface of the active region 50 may be lost.

Referring to FIG. 2D, the device isolation layer 60 is etched to a predetermined depth in order to form the fin type active region 50. In this case, since the process of etching the device isolation layer 60 in all regions with a uniform depth is very difficult, the fin type active region 50 may not be uniformly formed.

Referring to FIG. 2E, the gate 90 including the gate oxide layer 70, the gate polysilicon layer 75, the gate metal layer 80, and the gate hard mask layer 85 is disposed on the fin type active region 50. To form.

3 is a cross-sectional view illustrating a method of forming a semiconductor device according to the prior art, and is shown along the AA ′ direction of FIG. 1.

Referring to FIG. 3, the gate 90 is formed on the active region 50 protruding a predetermined height from the device isolation layer 60, the gate spacer 95 is formed on the sidewall of the gate 90, and the gate 90 is formed. The source / drain regions 97 are formed in the active region 50 between them. At this time, since the edge portion of the fin type active region 50 is missing, the area of the active region connected to the subsequent bit line contact and the storage node contact is reduced.

As described above, the method of forming a semiconductor device according to the related art forms an isolation layer and an active region by using an STI process. In this process, the pad oxide film and the pad nitride film are used, which makes the process complicated and removes the pad nitride film. There is a risk of losing the active area. The loss of the active region reduces the connection area of subsequent bit line contacts and storage node contacts, and the decrease in contact area causes an increase in contact resistance and a deterioration of electrical characteristics of the semiconductor device. In addition, the prior art uses a method of etching the device isolation film in order to form the active region in the fin shape, it is very difficult to uniformly adjust the height of the fin-type active region, the uniformity of the fin-type active region is reduced, the semiconductor There is a problem that the electrical characteristics of the device is degraded.

In order to solve the above problems, the present invention forms a first oxide layer, a nitride layer and a second oxide layer on the silicon substrate, and then pattern them to define an active region, and then pattern the exposed silicon substrate. By removing the second oxide layer after forming the epitaxial growth layer, a semiconductor device capable of improving the area securing and uniformity of the fin type active region while performing a simpler process than the conventional fin type active region forming process. It aims at providing the formation method.

In order to achieve the above object, the method of forming a semiconductor device according to the present invention

Sequentially forming a first oxide layer, a nitride layer, and a second oxide layer on the entire silicon substrate;

Forming a photoresist pattern on the second oxide layer to expose an active region;

Etching the second oxide layer, the nitride layer and the first oxide layer using the photoresist pattern as a mask to expose a silicon substrate;

Forming a silicon epitaxial growth layer on the exposed silicon substrate;

Removing the photoresist pattern and the second oxide layer and forming a fin type active region in the epitaxial growth layer; and

And forming a gate including the fin type active region.

Here, the first oxide film layer is formed to a thickness of 1500 ~ 2000Å, the nitride film is formed to a thickness of 400 ~ 600Å, the second oxide layer is formed to a thickness of 400 ~ 600Å, the epitaxial growth layer is Forming the height of the second oxide layer, removing the second oxide layer by a wet etching method, and forming an ion implantation process of a lightly doped drain (LDD) region and a gate sidewall insulating layer in the region between the gates after the gate formation. In this case, the ion implantation process of the source / drain region and the storage node contact and the bit line contact forming process connected to the source / drain region are sequentially performed.

Hereinafter, a method of forming a semiconductor device according to the present invention will be described in detail with reference to the accompanying drawings.

4 is a plan view illustrating a method of forming a semiconductor device according to the present invention.

Referring to FIG. 4, a fin type active region 120 is formed as a silicon epitaxial growth layer on the silicon substrate 100. Here, the active region 120 having a fin structure has a stacked structure of a first oxide layer (not shown), a nitride layer 140 and a second oxide layer (not shown) in the device isolation region, and then a silicon substrate in the active region. After epitaxial growth, the second oxide layer is removed. Next, the gate 190 is formed in a direction perpendicular to the length direction of the fin type active region 120.

5A to 5C are cross-sectional views illustrating a method of forming a semiconductor device in accordance with the present invention, and (i) of FIG. 4 is along the AA ′ direction of FIG. 4, and (ii) of FIG. 4 is BB of FIG. 4. 'Is shown along the direction.

Referring to FIG. 5A, the first oxide layer 130, the nitride layer 140, and the second oxide layer 150 are sequentially formed on the entire silicon substrate 100. Next, a photoresist pattern 160 is formed on the second oxide layer 150 to expose the active region. At this time, the first oxide film layer 130 is formed to a thickness of 1500 ~ 2000Å, the nitride film 140 is formed to a thickness of 400 ~ 600Å, the second oxide film layer 150 is formed to a thickness of 400 ~ 600Å desirable. Next, the second oxide layer 150, the nitride layer 140, and the first oxide layer 130 are sequentially etched using the photoresist pattern 160 as a mask to expose the silicon substrate 100. Next, a silicon epitaxial growth layer is formed in the region where the silicon substrate 100 is exposed. At this time, the silicon epitaxial growth layer is preferably formed to the height of the second oxide layer 150, the silicon epitaxial growth layer becomes the active region 120, the first oxide layer 130, the nitride film 140 And the second oxide layer 150 is a device isolation film, the active region 120 is formed by the epitaxial growth method can ensure a larger effective area than that formed by using a conventional STI process.

Referring to FIG. 5B, the photoresist pattern 160 and the second oxide layer 150 are removed. In this case, the second oxide layer 150 may be removed using a wet etching method. As a result, since the active region 120 is formed to protrude from the surface by a height of 'H', it becomes a fin-type active region 120. Here, the height of 'H' is 400 ~ 600Å as the height of the second oxide layer 150 is removed, the same height can be obtained in any region as shown in (i) and (ii).

Referring to FIG. 5C, the gate oxide layer 170, the gate polysilicon layer 175, the gate metal layer 180, and the hard mask layer 185 may be formed on the entire surface of the silicon substrate 100 including the fin type active region 120. After forming, the gate 190 is formed by sequentially etching the hard mask layer 185, the gate metal layer 180, the gate polysilicon layer 175, and the gate oxide layer 170 by an etching process using a gate mask. Next, an ion implantation process is performed to form a lightly dopant drain (LDD) region (not shown) in the active region 120 between the gates 190, and a spacer insulating layer 195 is formed on the sidewall of the gate 190. In addition, an ion implantation process is performed to form the source / drain region 200 in the active region 120. Next, storage node contacts (not shown) and bit line contacts (not shown) forming processes connected to the source / drain area 200 are sequentially performed.

FIG. 6 is a cross-sectional view illustrating a bit line contact according to the present invention and illustrates a cross section taken along the direction B1B1 ′ of FIG. 4.

Referring to FIG. 6, an isolation layer including a stacked structure of a first oxide layer and a nitride layer is provided on the silicon substrate 100, and a fin type active region 120 is provided in an area between the isolation layers. The region 120 includes a source / drain region 200 and a bit line contact 210 connected to the source / drain region 200. Here, since the active region 120 is formed using the silicon epitaxial growth method as described with reference to FIG. 5A, a larger area is secured and the area connected to the bit line contact 210 also increases.

FIG. 7 is a cross-sectional view illustrating a storage node contact according to the present invention, and illustrates a cross-section along B2B2 'in FIG. 4.

Referring to FIG. 7, like the bit line contact 210 of FIG. 6, a storage node contact 220 that is more stable and secures a large area is provided.

As described above, in the method of forming a semiconductor device according to the present invention, the first oxide layer, the nitride layer, and the second oxide layer may be formed on the silicon substrate without performing the device isolation film forming process using the STI process. After forming, they are patterned to define the active regions, and then an epitaxial growth layer is formed on the exposed silicon substrate, and the second oxide layer is removed, thereby performing a simpler process than the conventional fin type active region formation process. A fin type active region having a large area is formed, and the height of the fin portion can be formed the same anywhere by only removing the second oxide layer. In this case, securing the area of the active region serves to increase the connection area of the bit line contact and the storage node contact formed in a subsequent process to improve electrical characteristics of the semiconductor device.

As described above, in the method of forming a semiconductor device according to the present invention, after forming a first oxide layer, a nitride film, and a second oxide layer on the silicon substrate, which can act as device isolation layers, they are patterned to define active regions. Next, by forming an epitaxial growth layer on the exposed silicon substrate, the conventional trench isolation and pad nitride film processes may be omitted, and a wider active region may be secured. In addition, by removing the second oxide layer, it is possible to uniformly form the height of the fin type active region while performing a simpler process than the conventional fin type active region forming process. Accordingly, the present invention simplifies the process of forming a semiconductor device and provides an effect of improving electrical characteristics of the semiconductor device.

It will be apparent to those skilled in the art that various modifications, additions, and substitutions are possible, and that various modifications, additions and substitutions are possible, within the spirit and scope of the appended claims. As shown in Fig.

Claims (7)

Sequentially forming a first oxide layer, a nitride layer, and a second oxide layer on the entire silicon substrate; Forming a photoresist pattern on the second oxide layer to expose an active region; Etching the second oxide layer, the nitride layer and the first oxide layer using the photoresist pattern as a mask to expose a silicon substrate; Forming a silicon epitaxial growth layer on the exposed silicon substrate; Removing a second oxide layer around the photoresist pattern and the silicon epitaxial growth layer and forming a fin type active region in the epitaxial growth layer; And And forming a gate including the fin type active region. Claim 2 has been abandoned due to the setting registration fee. The method of claim 1, And the first oxide film layer is formed to a thickness of 1500 to 2000 GPa. Claim 3 has been abandoned due to the setting registration fee. The method of claim 1, The nitride film is a method of forming a semiconductor device, characterized in that formed in a thickness of 400 ~ 600Å. Claim 4 has been abandoned due to the setting registration fee. The method of claim 1, And the second oxide layer is formed to a thickness of 400 to 600 kV. Claim 5 was abandoned upon payment of a set-up fee. The method of claim 1, And forming the epitaxially grown layer up to a height of the second oxide film layer. Claim 6 has been abandoned due to the setting registration fee. The method of claim 1, And the second oxide layer is removed by a wet etching method. Claim 7 was abandoned upon payment of a set-up fee. The method of claim 1, After the gate is formed, an ion implantation process of a lightly dopant drain (LDD) region, a gate sidewall insulating layer formation, an ion implantation process of a source / drain region, and a storage node contact and a bitline contact connected to the source / drain region are formed in the region between the gates. A method of forming a semiconductor device, characterized in that the formation process is performed sequentially.

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