KR100576445B1 - Method for estimating the thickness of field oxide layer and chamical mechanical polishing in a process of manufacturing shallow trench isolation structures - Google Patents

Abstract

The present invention provides a method of forming a pad oxide layer on a semiconductor substrate, etching a portion of the pad oxide layer and the semiconductor substrate to form an alignment key, and forming the pad oxide layer and the pad oxide layer. Depositing a nitride film on an alignment key, etching the nitride film, the pad oxide film, and the semiconductor substrate to form a shallow trench, and field oxide to fill the shallow trench layer), and planarizing the field oxide layer by chemical mechanical polishing (CMP). In the case where there is residual nitride on the alignment key, the thickness of the field oxide film is thick, and the planarization is performed. If the estimate of a thin area to, not on the alignment key, the remaining nitride is thin and the thickness of the field oxide film, and estimates the thickness of the planarization of a thick area. According to the present invention, by simply estimating the thickness and planarization thickness of the field oxide film, it is possible to save time and reduce equipment dependency.

Align, align, STI

Description

METHODS FOR ESTIMATING THE THICKNESS OF FIELD OXIDE LAYER AND CHAMICAL MECHANICAL POLISHING IN A PROCESS OF MANUFACTURING SHALLOW TRENCH ISOLATION STRUCTURES}

1A to 1F are cross-sectional views sequentially illustrating a process of manufacturing a trench isolation layer in a semiconductor device;

2A and 2B are cross-sectional views sequentially illustrating a process of manufacturing a trench isolation layer of a semiconductor device that is not sufficiently planarized by chemical mechanical polishing (CMP);

FIG. 2C is a plan view of a trench isolation layer of the semiconductor device manufactured in FIG. 2B;

3A and 3B are cross-sectional views sequentially illustrating a process of fabricating a trench isolation layer of a semiconductor device that is sufficiently flattened by chemical mechanical polishing;

3C is a plan view of a trench isolation layer of the semiconductor device manufactured in FIG. 3B.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a shallow trench isolation layer (STI) of a semiconductor device, and more particularly, to a method of estimating the thickness and planarization thickness of a field oxide film by irradiating an alignment key.

1A to 1F are cross-sectional views illustrating a process of manufacturing a shallow trench isolation layer of a semiconductor device. With reference to these drawings will be described a shallow trench element separator manufacturing process.

As shown in FIG. 1A, a pad oxide layer 12 is formed on a silicon substrate 10, which is a semiconductor substrate.

As shown in FIG. 1B, a portion of the pat oxide film 12 and the semiconductor substrate 10 are etched to form a zero pattern by applying a photoresist, exposing and developing the photoresist. The portion that is etched in the zero pattern and lower than the periphery is later used as the align key 14, for example having a cross shape. The etched portion, ie, the align key 14, is then used to align in a later process, for example a process of forming a well implant pattern.

Next, as shown in FIG. 1C, a nitride film 16 is deposited on the pad oxide film 12 and the alignment key 14.

Then, as shown in FIG. 1D, a moat pattern 18 is formed on the nitride film 16. At this time, the mort pattern 18 is manufactured by applying a photoresist and exposing and developing the photoresist using a mask pattern of a shallow trench isolation layer (STI).

As illustrated in FIG. 1E, the nitride layer 16 and the pad oxide layer 12 that are stacked by, for example, a dry etching process are patterned using the mort pattern 18. Then, the semiconductor substrate 10 exposed by the pattern of the nitride film 16 and the pad oxide film 12 is etched to a predetermined depth to form a shallow trench 20 in which a shallow trench isolation layer is to be fabricated. Remove (18).

Then, as shown in FIG. 1F, a field oxide layer 22 as a gap-fill insulating film is deposited so that the shallow trench is buried.

The surface oxide film 22 is planarized by chemical mechanical polishing (CMP) until the nitride film 16 is exposed. At this time, as shown in FIG. 2A, the field oxide film 22 including the field oxide film 22 'on the alignment key 14 may not be sufficiently removed and may remain on the nitride film 16. In this case, when the nitride film 16 and the pad oxide film 12 are removed to form a shallow trench isolation film, as shown in FIG. 2B, the remaining nitride film 16 is disposed under the portion due to the remaining field oxide film 22. This leaves you with a problem. If the residual nitride 16 remains on the align key 14, the inspection equipment does not coincide with the reference image that the inspection target has as the align target and the actual image, so that it cannot be automatically aligned. Therefore, it was necessary to know the thickness of the field oxide film 22 and the thickness flattened with CMP in order to find out the occurrence of the residual nitride film 16 or to prevent the occurrence of the residual nitride film 16. There was a problem that wasted time and high dependence on equipment.

 The present invention has been implemented to solve this problem of the prior art, by irradiating the alignment key in the scribe line after chemical mechanical polishing (CMP), the thickness of the field oxide film and Its purpose is to provide a method for estimating planarization thickness.

According to a preferred embodiment of the present invention for achieving the above object, forming a pad oxide layer on the semiconductor substrate, and etching the portion of the pad oxide layer and the semiconductor substrate to align the key (align key) Forming a shallow trench by etching a nitride film on the pad oxide film and the alignment key, etching the nitride film, the pad oxide film, and the semiconductor substrate; Deposition of a field oxide layer so as to fill the shallow trench, and planarizing the field oxide layer by chemical mechanical polishing, the thickness and planarization thickness of the field oxide layer in the trench device isolation layer manufacturing process of the semiconductor device In the method of estimating, the field oxide film when there is residual nitride on the alignment key In the case where the thickness is thin and the planarization thickness is thin, and there is no residual nitride on the alignment key, the thickness and the planarization thickness of the field oxide film are assumed to be thin, and the planarization thickness is thick. It provides a method of estimating.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The process of planarizing the field oxide layer deposited in the manufacturing process of the shallow trench device isolation layer using chemical mechanical polishing (CMP) is the same as in the prior art and will be omitted. The process of will be described.

2A and 2B are cross-sectional views sequentially illustrating a process of fabricating a trench isolation layer of a semiconductor device that is not sufficiently planarized by chemical mechanical polishing.

As shown in FIG. 2A, when the thickness of the deposited field oxide film 22 is thick or not sufficiently planarized, the field oxide film 22 including the field oxide film 22 'on the alignment key 14 is formed. It cannot be sufficiently removed and remains on the nitride film 16. The reason is that the thickness of the field oxide film 22 deposited in FIG. 1F was thick or did not sufficiently flatten in FIG. 1G. In this case, when the nitride film 16 and the pad oxide film 12 are removed to form a shallow trench isolation film, as shown in FIG. The problem remains that this cannot be removed.

FIG. 2C is a plan view of the trench isolation layer of the semiconductor device manufactured in FIG. 2B, and an align key 14 is shown, for example, in a cross shape. As shown in FIG. 2C, by examining the align key 14 in the scribe line 30, residual nitride 16 is observed on the align key 14. This means that the area is not sufficiently planarized, or that the field oxide film 22 in that area is thick. That is, the thickness and planarization degree of the stacked field oxide film 22 can be estimated simply by looking at the alignment key 14 in the scribe line 30 without using inspection equipment.

As the degree of planarization is weaker, more residual nitride 16 remains on the align key 14 in the scribe line 30, so that the area of the remaining oxide 16 remains thicker in the thickness of the field oxide layer 22. In other words, it means that there is a high probability that the remaining nitride (16) remaining in the vicinity.

If the residual nitride 16 remains on the align key 14, an error occurs because the actual image does not coincide with the reference image that the inspection equipment has as the align target. In other words, the pixel distribution of the alignment key 14, that is, the cross key, which the inspection equipment stores as an alignment point does not coincide with the actual pixel distribution, so that the alignment cannot be automatically aligned. Must be aligned manually.

3A and 3B are cross-sectional views sequentially illustrating a process of fabricating a trench device isolation film of a semiconductor device sufficiently flattened by chemical mechanical polishing, and FIG. 3C is a plan view of the trench device isolation film of the semiconductor device fabricated in FIG. 3B.

As shown in FIG. 3A, when the thickness of the deposited field oxide film 22 is not thick or sufficiently flattened, all of the field oxide film 22 on the alignment key 14 is removed. In this case, when the nitride film 16 and the pad oxide film 12 are removed to form a shallow trench isolation film, as shown in FIG. 3B, the nitride film 16 on the alignment key 14 is left without being removed. do.

As shown in FIG. 3C, by examining the align key 14 in the scribe line 30, the residual nitride 16 is not observed on the align key 14 and has a clear image. . This means that the area is sufficiently flattened, or that the field oxide film 22 in that area is not thick. That is, by simply looking at the align key 14 in the scribe line 30 without going through the inspection equipment, it can be estimated that there is no residual nitride 16 in the vicinity thereof.

If there is no residual nitride 16 on the align key 14, the inspection equipment will match the reference image that the inspection equipment has as an align target and the actual image, thereby reducing errors. In other words, the pixel distribution of the alignment key, that is, the cross key 14, which the inspection equipment stores as an alignment point coincides with the actual pixel distribution, the alignment can be automatically performed and the user You do not have to manually align the alignment.

According to the present invention, it is possible to provide a method for estimating the thickness and leveling degree of a field oxide film by irradiating an alignment key in a scribe line after chemical mechanical polishing (CMP).

Claims (2)

Forming a pad oxide layer on the semiconductor substrate, etching the pad oxide layer and a portion of the semiconductor substrate to form an alignment key, and forming the pad oxide layer and the alignment key Depositing a nitride film on the substrate, etching the nitride film, the pad oxide film, and the semiconductor substrate to form a shallow trench, and forming a field oxide layer to fill the shallow trench In the method of estimating the thickness and planarization thickness of the field oxide film in the trench device isolation film manufacturing process comprising the step of depositing, and planarizing the field oxide film by chemical mechanical polishing (CMP), If there is residual nitride on the alignment key, the field oxide film is assumed to be thick and the planarization thickness is thin. And estimating a thickness and a planarization thickness of the field oxide film, which are assumed to be thin regions where the thickness of the field oxide film is thin and the planarization thickness is thick when there is no residual nitride on the alignment key. The method of claim 1, And the alignment key has a cross shape.

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