KR19980038880A - Device Separating Method of Semiconductor Device - Google Patents

Abstract

The present invention relates to a method for forming a device isolation film of a semiconductor device, comprising: providing a semiconductor substrate having a thermal oxide film pattern formed thereon; Implanting impurities into the entire surface of the semiconductor substrate to form a nitrogen ion layer in the exposed semiconductor substrate; Forming spacers on sidewalls of the thermal oxide pattern; Etching the nitrogen ion layer using a spacer as an etch mask to form a trench in the nitrogen ion layer; Forming a first field oxide layer by performing a high temperature heat treatment on the trench where the trench is formed; Forming an oxide film having a predetermined thickness over the whole; And etching the oxide film, the spacer, and the thermal oxide film pattern by chemical mechanical polishing to form a second field oxide film.

Description

A device isolation film formation method for a semiconductor device.

The present invention relates to a method of forming a device isolation film of a semiconductor device, and more particularly, to a method of forming a device isolation film of a semiconductor device in which a trench-type field oxide film is formed to improve insulation characteristics.

In the manufacturing process of a semiconductor device, in order to isolate or insulate an element from an element, an element isolation film is formed between the elements, and a conventional method for forming such an element isolation film is a local process using a thermal oxidation process. The device isolation film formation method by oxidation of silicon (LOCOS) is mainly used.

However, the method of forming a device isolation layer using the LOCOS technology has a problem in that the active area of the device is reduced due to the bird's beak generated during the thermal oxidation process, which causes a decrease in the integration and electrical characteristics of the semiconductor device. Will act as.

Therefore, as another conventional method for solving the above problems, a method of forming an isolation layer using a trench has been used, and a method of forming an isolation layer of a semiconductor device using a trench is described below with reference to FIGS. 1A to 1E. .

Referring to FIG. 1A, a thermal oxide film 2 having a predetermined thickness is formed on a semiconductor substrate 1, and an oxidation-resistant nitride film pattern 3 is formed on the thermal oxide film 2. Then, oxygen ions are implanted into the entire surface of the semiconductor substrate 1 using the nitride film pattern 3 as a mask, and an oxygen ion layer 4 is formed in the exposed semiconductor substrate 1.

Referring to FIG. 1B, an oxide film spacer 5 is formed on a sidewall of the nitride film pattern 3 by a known method, and a trench 10 is formed in the oxygen ion layer 4 by an etching process using the oxide film spacer 5 as an etching mask. ) Is formed.

Referring to FIG. 1C, a thermal oxidation process is performed on the oxygen ion layer 4 on which the trench 10 is formed, and as a result, the first field oxide film 4 ′ is formed on the oxygen ion layer 4.

Referring to FIG. 1D, in order to fill the inside of the trench 10, a CVD (chemical vapor deposition) oxide film 7 is formed over the entire portion.

Referring to FIG. 1E, the CVD oxide film 6 and the oxide film spacer 5 are etched back to expose the first field oxide film 4 ′. At this time, the second field oxide film 7 is formed in the first field oxide film 4 '. Then, the oxidation nitride film pattern 3 and the thermal oxide film 2 are removed by the etching process.

However, in the conventional method as described above, during the etch back process of the CVD oxide film and the oxide spacer, it is difficult to set an end point of the CVD oxide film. Thus, there is a problem that excessive etching occurs and the surface of the field oxide film is damaged.

Therefore, in order to solve the above problems, the present invention forms a nitrogen ion layer in a semiconductor substrate and a trench type field oxide film is formed in the nitrogen ion layer, thereby preventing excessive etching to prevent surface damage of the field oxide film. An object of the present invention is to provide a device isolation film formation method of a device.

1A to 1E are a series of cross-sectional views illustrating a method of forming a device isolation film of a semiconductor device according to the prior art.

2A to 2E are a series of cross-sectional views for explaining a method of forming a device isolation film of a semiconductor device according to the present invention.

3A to 3F are a series of cross-sectional views for explaining a method of forming a device isolation film of a semiconductor device according to a second embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

11,21: semiconductor substrate 12: thermal oxide film pattern

l, 25: nitrogen ion layer 13 ', 25': first field oxide film

14,26 oxide film spacer 15 CVD oxide film

l6,28: second field oxide film 22: thermal oxide film

23 polysilicon film 24 first CVD film

27: second CVD film 20, 30: trench

The above object is to provide a semiconductor substrate on which a thermal oxide film pattern is formed; Implanting impurities into the entire surface of the semiconductor substrate to form a nitrogen ion layer in the exposed semiconductor substrate; Forming spacers on sidewalls of the thermal oxide pattern; Etching the nitrogen ion layer using a spacer as an etch mask to form a trench in the nitrogen ion layer; Forming a first field oxide layer by performing a high temperature heat treatment on the trench where the trench is formed; Forming an oxide film having a predetermined thickness over the whole; And etching the oxide film, the spacer and the thermal oxide film pattern by chemical mechanical polishing to form a second field oxide film.

In addition, the above object is to provide a semiconductor substrate having a thermal oxide film, a polysilicon film and a first oxide film; Exposing the thermal oxide film by photolithography; Forming a nitrogen ion layer in the exposed semiconductor substrate by implanting nitrogen ions into the entire surface of the semiconductor substrate; Forming a spacer on sidewalls of the first oxide film; Etching the nitrogen ion layer using a spacer as a mask to form a trench in the nitrogen ion layer; Forming a first field oxide layer by performing a high temperature heat treatment on the trench where the trench is formed; Forming a second oxide film having a predetermined thickness on the entire upper portion; Etching the second oxide film, the spacer, and the first oxide film by chemical mechanical polishing until the polysilicon film is exposed to form a second field oxide film; And removing the polysilicon film and the thermal oxide film.

According to the present invention, by forming the trench type field oxide film inside the nitrogen ion layer, it is possible to prevent surface damage of the field oxide film, thereby improving the insulation characteristics of the semiconductor device.

[Example]

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to FIGS. 2A to 2E.

Referring to FIG. 2A, a thermal oxide pattern 12 is formed on the semiconductor substrate 11, and about 1 × 10 ¹³ to 1 × 10 ¹⁶ on the entire surface of the semiconductor substrate 11 using the thermal oxide pattern 12 as a mask. The nitrogen ion layer 13 is formed in the exposed semiconductor substrate 11 by the implantation of nitrogen ions under the condition of atoms / cm 3, about 50 to 100 KeV.

Referring to FIG. 2B, an oxide spacer 14 is formed on a sidewall of the thermal oxide pattern 12 by a known method, and a trench 20 is formed in the nitrogen ion layer 13 by an etching process using the oxide spacer 14 as a mask. Is formed. Here, since the thermal oxide pattern 12 is also etched during the etching process for forming the trench 10, the deeper the trench 20 becomes, the thinner the thickness of the thermal oxide film 12 is.

Referring to FIG. 2C, the nitrogen ion layer 13 on which the trench 20 is formed is heat-treated at a high temperature, whereby a first field oxide film 13 ′ is formed in the nitrogen ion layer 13.

Referring to FIG. 2D, a CVD oxide film 16 having a predetermined thickness is formed over the entire trench 20 to fill the trench 20.

Referring to FIG. 2E, the CVD oxide layer 16, the oxide spacer 14, and the thermal oxide layer pattern 12 are removed by chemical mechanical polishing until the first field oxide layer 15 is exposed. In this case, the first field oxide film 4 ′ formed of the nitrogen ions is used as an etch stop layer, and a trench type second field oxide film 7 is formed in the first field oxide film 15.

Another embodiment of the present invention will be described with reference to FIGS. 3A to 3F.

Referring to FIG. 3A, a thermal oxide film 22, a polysilicon film 23, and a first CVD oxide film 24 having a predetermined thickness are sequentially formed on the semiconductor substrate 21 to expose the thermal oxide film 22. For this purpose, the first CVD oxide film 24 and the polysilicon film 23 are photo-etched. Then, a nitrogen ion implantation process using the first CVD oxide film 24 as a mask is performed on the entire surface of the semiconductor substrate 21, and as a result, the nitrogen ion layer 25 is formed in the exposed semiconductor substrate 21. At this time, the nitrogen ions are implanted under the conditions of about 1 × 10 ¹³ to 1 × 10 ¹⁶ atoms / cm 3 and about 50 to 100 KeV.

Referring to FIG. 3B, an oxide film spacer 26 is formed on the sidewall of the first CVD oxide film 24 by a known method, and trenches in the nitrogen ion layer 25 are formed by an etching process using the oxide spacer 26 as an etching mask. 30) is formed. Here, since the first CVD oxide film 24 is also etched during the etching process for forming the trench 30, the deeper the trench 30 is, the thinner the first CVD oxide film 24 is.

Referring to FIG. 3C, the nitrogen ion layer 25 having the trench 30 formed thereon is subjected to high temperature heat treatment, whereby a first field oxide film 25 ′ is formed in the nitrogen ion layer 25.

Referring to FIG. 3D, a second CVD oxide film 27 having a predetermined thickness is formed over the entire trench 30 to fill the trench 30.

Referring to FIG. 3E, the second CVD oxide film 27, the oxide spacer 26, and the first CVD oxide film 24 are removed by a chemical mechanical polishing process. In this case, the polysilicon film 23 is used as an etch stop layer, and a second field oxide film 28 is formed in the first field oxide film 25 ′.

Referring to FIG. 3F, the polysilicon layer 23 and the thermal oxide layer 22 are sequentially removed by a known etching process, and a trench type field oxide layer 28, 25 ′ having a double structure is formed in a predetermined region of the semiconductor substrate 21. ) Is formed.

As described above, the device isolation film forming method of the semiconductor device of the present invention can prevent surface damage of the field oxide film due to excessive etching by forming a nitride film in the semiconductor substrate, and insulates by forming a trench type field oxide film having a double structure. Properties can be improved.

Meanwhile, although specific embodiments of the present invention have been described and illustrated, modifications and variations can be made by those skilled in the art. Accordingly, the following claims are to be understood as including all modifications and variations as long as they fall within the true spirit and scope of the present invention.

Claims (8)

Providing a semiconductor substrate having a thermal oxide film pattern formed thereon; Implanting impurities into the entire surface of the semiconductor substrate to form a nitrogen ion layer in the exposed semiconductor substrate; Forming spacers on sidewalls of the thermal oxide pattern; Etching the nitrogen ion layer using a spacer as an etch mask to form a trench in the nitrogen ion layer; Forming a first field oxide layer by performing a high temperature heat treatment on the trench where the trench is formed; Forming an oxide film having a predetermined thickness over the whole; And etching the oxide film, spacer and thermal oxide film pattern by chemical mechanical polishing to form a second field oxide film. The method of claim 1, wherein the nitrogen ions are implanted under conditions of about 1 × 10 ¹³ to 1 × 10 ¹⁶ atoms / cm 3, about 50 to 100 KeV. The method of claim 1, wherein the oxide film is a CVD oxide film. 2. The method of claim 1, wherein a first field oxide film is used as the etch stop layer during chemical mechanical polishing. Providing a semiconductor substrate on which a thermal oxide film, a polysilicon film, and a first oxide film are formed; Exposing the thermal oxide film by photolithography; Forming a nitrogen ion layer in the exposed semiconductor substrate by implanting nitrogen ions into the entire surface of the semiconductor substrate; Forming a spacer on sidewalls of the first oxide film; Etching the nitrogen ion layer using a spacer as a mask to form a trench in the nitrogen ion layer; Forming a first field oxide layer by performing a high temperature heat treatment on the trench where the trench is formed; Forming a second oxide film having a predetermined thickness on the entire upper portion; Etching the second oxide film, the spacer and the first oxide film by chemical mechanical polishing until the polysilicon film is exposed to form a second field oxide film; And removing the polysilicon film and the thermal oxide film. 6. The method of claim 5 wherein the nitrogen ions are implanted under conditions of about 1 × 10 ¹³ to 1 × 10 ¹⁶ atoms / cm 3, about 50 to 100 KeV. 6. The method of claim 5, wherein the first oxide film and the second oxide film are CVD oxide films. 6. The method of claim 5, wherein a polysilicon film is used as an etch stop layer in the chemical mechanical polishing process.