KR100791779B1 - Method for isolating a active cell of a semiconductor device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device isolation method of a semiconductor device. In the present invention, before a series of thermal oxidation processes for forming a device isolation film are performed, a series of targets of a buffer oxide film stacked on a semiconductor substrate is targeted. After several preliminary impurity implantation processes, the impurities are naturally induced to form a series of anti-oxidation barriers at a specific interface of the buffer oxide film during the thermal oxidation process. Even if a part of the device isolation film is unnecessarily grown by high temperature heat, the unnecessary growth region is blocked in advance so that the unnecessary growth region does not easily penetrate into the active area of the active device due to the interference of the anti-oxidation penetration film.

According to the embodiment of the present invention, the formation of unnecessary bird beak regions is suppressed, whereby the active region of each active element can be secured widely, the finally formed semiconductor device naturally acquires a series of high integration effects You can do it.

Description

Method for isolating a active cell of a semiconductor device

1 to 4 are process flow charts sequentially showing a device isolation method of a semiconductor device according to the prior art.

5 to 10 are process flowcharts sequentially illustrating a method of separating elements of a semiconductor device according to the present invention.

The present invention relates to a device isolation method of a semiconductor device, and more particularly, prior to a series of thermal oxidation processes for forming a device isolation film, targeting a specific interface of a buffer oxide film stacked on a semiconductor substrate, After performing a series of impurity implantation steps several times, during the full-scale thermal oxidation process, these impurities are added during the thermal oxidation process by inducing them to naturally form a series of anti-oxidation barrier films at a specific interface of the buffer oxide film. Even if a part of the device isolation film is unnecessarily grown by high temperature heat, the device isolation of the semiconductor device can be blocked in advance so that the unnecessary growth region does not easily penetrate into the active area of the active device due to the interference of the oxidation barrier film. It is about a method.

In general, when fabricating a semiconductor device, it is common for each active element to be electrically insulated from each other, and for this purpose, conventionally, for example, a LOCOS (Local Oxide of Silicon) process is performed to between each active region. By forming the insulating device isolation film, each active device formed on the semiconductor substrate is induced to smoothly perform stable circuit operation in a state electrically independent of each other.

Such a structure, a manufacturing method, and the like of a conventional device isolation layer are described, for example, in U.S. Patent No. 5326715, "Method for forming a field oxide film of a semiconductor device," U.S. Patent No. 5674776. Semiconductor processing methods of forming field oxidation regions on a semiconductor substrate, US Patent No. 5700733 "Field oxide regions on a semiconductor substrate." US Patent Publication No. 5726092, "Semiconductor processing methods of forming field oxidation regions on a semiconductor substrate," US Patent No. 5728622, "Field of Semiconductor Devices." Process for forming field oxide layers in semiconductor devices. " .

In general, under a conventional device isolation method, for example, a PBL process (Poly Buffered Local Oxidation of silicon process), the device isolation film is a buffer oxide film 2, a polysilicon on the semiconductor substrate 1, as shown in FIG. Through the steps of forming the film 3, the nitride film 4, and the like, and through a series of etching processes using the photosensitive film pattern 5, as shown in FIG. 2, a part 3a of the polysilicon film 3 is formed. By removing the nitride film 4 so as to remain, opening the field planned region and through a series of thermal oxidation processes, as shown in FIG. 3, the device isolation film 6 is formed in the field planned region of the semiconductor substrate 1. Is grown, and as illustrated in FIG. 4, the manufacturing is completed by removing the nitride film 4, the polysilicon film 3, the buffer oxide film 2, and the like used during the process.

Under this conventional PBL process regime, as described above, the device isolation film 6 is finally formed through a high temperature thermal oxidation process. In this situation, if no further action is taken, it is applied during the thermal oxidation process. Due to the high-temperature heat, the ear portion of the device isolation film 6 is forced to achieve unnecessary growth. As a result, the so-called " Bird beak region "

The beak region B formed as described above penetrates deeply into the active regions A1 and A2 of the active element formed on the semiconductor substrate 1, thereby causing a serious problem of greatly narrowing the active regions A1 and A2 of the active element. Done.

Under the conventional PBL process system, as described above, the polysilicon film 3 is formed in advance on the buffer oxide film 2, and the polysilicon film 3 can suppress unnecessary growth of a part of the device isolation film 6. By acting as a factor, it is possible to prevent the complicated problem caused by the bird beak area in advance.

However, due to the inherent characteristics of the polysilicon film 3, when a series of thermal oxidation processes for forming the device isolation film 6 are performed, the polysilicon film 3, together with the device isolation film 6, is somewhat to some extent. Inevitably, a certain beak area B of a certain size is inevitably formed in a part of the device isolation film 6 even under a conventional arrangement of the polysilicon film 3, unless a further action is taken. As a result, in spite of the conventional arrangement of the polysilicon film 3, it is inevitable to suffer the problem of narrowing the active regions A1 and A2 of the active element.

Accordingly, an object of the present invention is to target a specific interface of a buffer oxide film stacked on a semiconductor substrate before a series of thermal oxidation processes for forming a device isolation film, and a series of impurity implantation processes may be performed several times. After proceeding in advance, during the full thermal oxidation process, the impurities may naturally form a series of anti-oxidation barrier films at a specific interface of the buffer oxide film, so that a part of the device isolation layer is removed by the high temperature heat applied during the thermal oxidation process. Even if it grows unnecessarily, the unnecessary growth region is blocked in advance so that it cannot easily penetrate into the active region of the active element due to the interference of the oxidation-intrusion prevention film.

Another object of the present invention is to suppress the formation of unnecessary bird beak regions through the action of the anti-oxidation penetration film, thereby inducing a wide range of active regions of active elements, thereby naturally realizing high integration of semiconductor devices. have.                         

Still other objects of the present invention will become more apparent from the following detailed description and the accompanying drawings.

In order to achieve the above object, in the present invention, a buffer film, a polysilicon film, and a mask film are sequentially stacked on the entire surface of the semiconductor substrate, and a first ion implantation process is used to form a first layer at an interface between the semiconductor substrate and the buffer film. Implanting chain ions, implanting second chain ions at an interface between the buffer film and the polysilicon film using a secondary ion implantation process, and selectively patterning the mask film and the polysilicon film, Opening the predetermined region and using a thermal oxidation process to grow the device isolation layer in the field predetermined region, and deform the first chain ions and the second chain ions into separate anti-oxidation barriers, A device isolation method of a semiconductor device comprising a combination of steps to suppress unnecessary growth is disclosed.

Hereinafter, with reference to the accompanying drawings, the device isolation method according to the present invention in more detail.

As shown in FIG. 5, in the present invention, a series of deposition processes are first performed to form a buffer film, for example, a buffer oxide film 12, on the entire surface of the semiconductor substrate 11. In this case, the buffer oxide film 12 serves to reduce crystal defects of the semiconductor substrate 1.

Then, in the present invention, a series of chemical vapor deposition processes are performed to form the polysilicon film 13 on the buffer oxide film 12. In this case, the polysilicon layer 13 absorbs stress that may be applied to the semiconductor substrate 1 side when the mask layer 14 is formed later, thereby protecting the semiconductor substrate 11 from stress. do.

Next, in the present invention, a series of chemical vapor deposition processes are performed to form a mask film, for example, a nitride film 14 made of Si ₃ N ₄ , on the polysilicon film 13. In this case, the nitride film 14 serves as a mask for the device isolation film formed later.

When the stacking of the buffer oxide film 12, the polysilicon film 13, the nitride film 14, etc. is sequentially completed on the entire surface of the semiconductor substrate 1 through the foregoing procedures, in the present invention, a series of 1 The secondary ion implantation process is performed to inject first chain ions, for example, nitrogen ions, into the interface between the semiconductor substrate 11 and the buffer oxide film 12, and thereby, through the First ion implantation layer 20a is formed.

In the state in which the first ion implantation layer 20a is formed at the interface between the semiconductor substrate 11 and the buffer oxide film 12, in the present invention, as shown in FIG. 6, a series of secondary ion implantation processes are further performed. In some embodiments, the second chain ions, for example, nitrogen ions are implanted at the interface between the buffer oxide layer 12 and the polysilicon layer 13, and thus, a series of second ion implantation layers are formed at the interface. (21a) is formed.

On the other hand, when the formation of the series of the first ion implantation layer 20a and the second ion implantation layer 21a is completed through the above-described process, in the present invention, a photosensitive film is coated on the nitride film 14, The photosensitive film is exposed and developed to form a photosensitive film pattern 15 as shown in FIG.

Subsequently, using the photoresist pattern 15 as an etching mask, a dry etching process having a series of anisotropic characteristics, for example, a reactive ion etching process, is performed to perform the nitride film 14 and the polysilicon film 13. 8), a portion of the substrate is etched, thereby opening a series of field predetermined regions on the upper portion of the semiconductor substrate 110, as shown in Fig. 8. Then, the previous photoresist pattern 15 is removed.

In this case, the polysilicon film 13a remaining in the open region of the entire polysilicon film 13 assists in stably suppressing generation of unnecessary bird beak regions when the device isolation film described later is formed.

Through the above process, when a series of field scheduled regions are opened on the semiconductor substrate 11, in the present invention, a series of thermal oxidation processes are immediately performed on the field scheduled regions, and as shown in FIG. As described above, a series of element isolation films 16 are formed in the field region of the semiconductor substrate 11.

In this case, as mentioned above, in the present invention, the semiconductor substrate 11 and the buffer oxide film 12 are interposed between the semiconductor substrate 11 and the buffer oxide film 12 through a series of ion implantation processes before the full-scale thermal oxidation process proceeds. Since a series of first ion implantation layers 20a and second ion implantation layers 21a are formed in advance between 120 and the polysilicon film 13, a full-scale thermal oxidation process for realizing the device isolation film 16 is performed. In this case, the first and second ion implantation layers 20a and 21a react quickly by the heat applied during the thermal oxidation process, for example, the first and second oxidation penetration barriers 20 and 21 having a SiON material. It can be formed naturally.

As described above, the first and second anti-oxidation barrier films 20 and 21 formed as described above, for example, take a mechanism for blocking the outer portion of the device isolation film 16, and finally, under the framework of the present invention, Even if a part of the device isolation film 16 is unnecessarily grown by the high temperature heat applied during the thermal oxidation process, the unnecessary growth region is formed in the active device due to the interference of the first and second anti-oxidation barrier films 20 and 21. It does not penetrate easily into active areas A1 and A2.

Of course, since the first and second anti-oxidation penetration films 20 and 21 inherent to the present invention are completely independent of the oxidation of the device isolation film, the unnecessary oxidation region prevention function given to the present invention is compared with that of the conventional polysilicon film. You can do it more effectively.

According to the embodiment of the present invention, the formation of unnecessary bird beak regions is suppressed, whereby, when the active regions A1 and A2 of each active element can be secured widely, the finally formed semiconductor device has a series of high integration effects. Can be obtained naturally.

Subsequently, in the present invention, a series of etching processes are performed to sequentially remove the nitride film 14, the polysilicon film 13, the buffer oxide film 12, and the like remaining on the semiconductor substrate 11, as shown in FIG. As described above, a high quality device isolation film 16 is manufactured.

As described in detail above, in the present invention, a series of impurity implantation processes may be performed by targeting a specific interface of a buffer oxide film stacked on a semiconductor substrate before a series of thermal oxidation processes for forming an isolation layer are performed. After proceeding in advance, during the full thermal oxidation process, the impurities are naturally induced to form a series of anti-oxidation barrier films at a specific interface of the buffer oxide film, and thus the device is separated by the high temperature heat applied during the thermal oxidation process. Even if part of the growth is unnecessary, the unnecessary growth region is blocked in advance so that the unnecessary growth region does not easily penetrate into the active region of the active element due to the interference of the anti-oxidation penetration film.

According to the embodiment of the present invention, the formation of unnecessary bird beak regions is suppressed, whereby the active region of each active element can be secured widely, the finally formed semiconductor device naturally acquires a series of high integration effects You can do it.

While specific embodiments of the invention have been described and illustrated above, it will be apparent that the invention may be embodied in various modifications by those skilled in the art. Such modified embodiments should not be understood individually from the technical spirit or point of view of the present invention and such modified embodiments should fall within the scope of the appended claims of the present invention.

Claims (3)

Sequentially laminating a buffer film, a polysilicon film, and a mask film on the entire surface of the semiconductor substrate; Implanting first chain ions at an interface between the semiconductor substrate and the buffer film using a primary ion implantation process; Implanting second chain ions at an interface between the buffer film and the polysilicon film using a secondary ion implantation process; Selectively patterning the mask film and the polysilicon film to open a field predetermined area; By using a thermal oxidation process, the device isolation film is grown in the field predetermined region, and the first chain ions and the second chain ions are transformed into a separate anti-oxidation penetration film, thereby suppressing unnecessary growth of a part of the device isolation film. Device isolation method of a semiconductor device comprising the step. The method of claim 1, wherein the first and second chain ions are nitrogen ions. 2. The method of claim 1, wherein the anti-oxidation penetration film is a silicon nitride film.

Images