KR101059810B1 - Method of manufacturing semiconductor device - Google Patents

Abstract

The present invention discloses a method for manufacturing a semiconductor device for preventing the deterioration of device characteristics. The disclosed method comprises the steps of providing a silicon substrate having active and field regions defined therein; Sequentially forming a pad oxide film and a pad nitride film exposing the field region on the silicon substrate; Etching a field region of the exposed substrate to form a trench; Sequentially forming an oxide film and a first nitride film on the substrate resultant; Forming a buried oxide film to fill the trench in the entire surface of the resultant material; Forming a device isolation film by CMP the resultant material until the pad nitride film is exposed; Removing the pad nitride film and etching a portion of the remaining first nitride film; Removing a portion of the remaining oxide film while simultaneously removing the pad oxide film; Forming a floating gate on an active region of the resulting substrate; Forming a second nitride film on an entire surface of the substrate including the floating gate; And etching the second nitride film to form first spacers on both sidewalls of the floating gate, and simultaneously forming second spacers connected to the remaining first nitride film on an upper sidewall of the device isolation layer. .

Description

Manufacturing method of semiconductor device {METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE}

1A to 1F are cross-sectional views illustrating processes for manufacturing a semiconductor device according to the related art.

2 is a cross-sectional view for explaining a problem according to the prior art.

3A to 3G are cross-sectional views of processes for describing a method of manufacturing a semiconductor device, according to an embodiment of the present invention.

Explanation of symbols on main parts of drawing

30 silicon substrate 31 pad oxide film remaining after patterning

32: pad nitride film remaining after patterning 33: trench

34: thermal oxide film 35: TEOS oxide film

36: first nitride film 37: buried oxide film

35a: TEOS oxide film remaining after CMP 36a: first nitride film remaining after CMP

35b: TEOS oxide film remaining after cleaning process 36b: First nitride film remaining after etching

37a: device isolation layer 38: tunnel oxide layer

39 polysilicon film 40 hard mask film

41: floating gate 42: second nitride film

42a: first spacer 42b: second spacer                 

A: rounding

The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a method for manufacturing a semiconductor device capable of preventing the deterioration of device characteristics.

With the progress of semiconductor technology, the speed and the high integration of semiconductor devices are progressing rapidly, and with this, the demand for refinement | miniaturization of a pattern and high precision of a pattern dimension is increasing. This requirement applies not only to patterns formed in device regions, but also to device isolation films that occupy a relatively large area. This is because the width of the device region must decrease in order to increase the width of the device region in the trend that the width of the device region is decreasing toward the highly integrated device.

Here, a conventional device isolation film has been formed by a LOCOS process, and the device isolation film by the LOCOS process, as is well known, has a bird's-beak having a beak shape at its edge portion. Since it is generated, there is a disadvantage in that a leakage current is generated while increasing the area of the device isolation film.

Therefore, instead of the method of forming a device isolation film by the LOCOS process, a method of forming a device isolation film using a shallow trench isolation (STI) process having a small width and excellent device isolation characteristics has been proposed. The device is an STI process to form a device isolation film.                         

1A to 1F are cross-sectional views of processes for describing a method of manufacturing a semiconductor device according to the related art.

A method of manufacturing a conventional semiconductor device to which the STI process is applied will be briefly described with reference to FIGS. 1A to 1F.

In the conventional method of manufacturing a semiconductor device, as shown in FIG. 1A, first, a pad oxide film (not shown) and a pad are formed on a silicon substrate 10 in which an active region (not shown) and a field region (not shown) are defined. A nitride film (not shown) is formed in sequence. Subsequently, the pad nitride film and the pad oxide film are patterned to expose the field region of the substrate 10. Next, the trench 13 having a predetermined depth is formed by etching the field region of the exposed substrate 10. In this case, reference numeral 11, which is not described in FIG. 1A, illustrates a pad oxide film remaining after patterning, and 12 illustrates a pad nitride film remaining after patterning.

Then, as illustrated in FIG. 1B, a thermal oxide layer 14 is formed on the surface of the trench 13 to round (A) the top corner of the trench 13. Subsequently, a buried oxide film 15 is formed on the entire structure of the resultant structure so as to fill the trench 13. In this case, a high density plasma (HDP) oxide film is used as the buried oxide film 15.

Then, as shown in FIG. 1C, the buried oxide layer is chemically mechanically polished (CMP) until the pad nitride layer is exposed to form the device isolation layer 15a. Next, the pad nitride film is removed. Thereafter, a washing process is performed to remove the pad oxide film. At this time, the cleaning process is carried out for 35 seconds using a solution (hereinafter referred to as HF solution) in which H20 and HF are mixed in a ratio of 19: 1.

Then, as shown in FIG. 1D, a tunnel oxide film 16 is formed on the silicon substrate 10, and then a polysilicon film 17 and a hard mask are formed on the resultant active region. A Floating Gate 19 having a structure in which a Mask film 18 is sequentially stacked is formed.

Subsequently, as shown in FIG. 1E, a nitride film 20 for spacers of the floating gate is formed on the entire surface of the substrate including the floating gate 19.

1F, the nitride film for spacers is etched to form floating gate spacers 20a on both sidewalls of the floating gate 19.

However, according to the prior art as described above, the following problems occur. 2 is a cross-sectional view illustrating a problem according to the prior art.

In the related art, as shown in FIG. 2, as the cleaning process using the HF solution for removing the pad oxide film proceeds, the buried oxide film of the upper corner portion of the device isolation layer 15a, that is, the HDP oxide film is excessively formed. Erosion causes moat (M). Therefore, in the subsequent etching process of the spacer nitride film of the floating gate, the spacer nitride film remains on the upper sidewall of the device isolation layer 15a which is the moat M generation portion. At this time, when the spacer nitride film B remaining after the etching is separated by a subsequent cleaning process, the active region is contaminated to deteriorate the characteristics of the device.

Accordingly, the present invention has been made to solve the above problems, in the spacer nitride film etching process of the floating gate, the spacer nitride film is left on the upper sidewall of the device isolation film, and then separated by a subsequent cleaning process It is an object of the present invention to provide a method for manufacturing a semiconductor device which can prevent contamination of the active region and prevent the deterioration of device characteristics.

According to an aspect of the present invention, there is provided a method of fabricating a semiconductor device, the method including: providing a silicon substrate in which an active region and a field region are defined; Sequentially forming a pad oxide film and a pad nitride film exposing the field region on the silicon substrate; Etching a field region of the exposed substrate to form a trench; Sequentially forming an oxide film and a first nitride film on the substrate resultant; Forming a buried oxide film to fill the trench in the entire surface of the resultant material; Forming a device isolation film by CMP the resultant material until the pad nitride film is exposed; Removing the pad nitride film and etching a portion of the remaining first nitride film; Removing a portion of the remaining oxide film while simultaneously removing the pad oxide film; Forming a floating gate on an active region of the resulting substrate; Forming a second nitride film on an entire surface of the substrate including the floating gate; And etching the second nitride film to form first spacers on both sidewalls of the floating gate, and forming a second spacer connected to the remaining first nitride film on an upper sidewall of the device isolation layer. .

Here, the oxide film is made of a TEOS oxide film, wherein the TEOS oxide film is formed to a thickness of 100Å by using TEOS and O2 gas at a temperature of 650 ℃ or more. In addition, the first nitride film is formed to a thickness of 100 kPa using a mixed gas of NH3 and SiCl2H2 at a temperature of 750 ℃ or more. In the etching of the remaining portion of the first nitride film, the first nitride film is wet-etched by a thickness of 800 kPa.

(Example)

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

3A to 3G are cross-sectional views of processes for describing a method of manufacturing a semiconductor device, according to an embodiment of the present invention.

In the method of manufacturing a semiconductor device according to an embodiment of the present invention, as shown in FIG. 3A, first, a pad oxide layer is formed on a silicon substrate 30 in which an active region (not shown) and a field region (not shown) are defined. A pad nitride film (not shown) is formed in this order. Subsequently, the pad nitride film and the pad oxide film are patterned to expose the field region of the substrate 30. Next, the field region of the exposed substrate 30 is etched to form a trench 33 having a predetermined depth. In this case, reference numeral 31, which is not described in FIG. 3A, indicates a pad oxide film remaining after patterning, and 32 indicates a pad nitride film remaining after patterning.

Then, as illustrated in FIG. 3B, a thermal oxide layer 34 is formed on the surface of the trench 33 to round (A) the upper corner of the trench 33. Subsequently, a TEOS (Tetra Ethyl Ortho Sillicate) oxide film 35 is formed on the substrate resultant. At this time, the TEOS oxide layer 35 is formed to a thickness of 100 kV using TEOS (Tetra Ethyl Ortho Sillicate) and O2 gas at a temperature of 650 ℃ or more.

Thereafter, a first nitride film 36 is formed on the TEOS oxide film 35. At this time, the first nitride film 36 is formed to a thickness of 100 kPa using a mixed gas of NH 3 and SiCl 2 H 2 at a temperature of 750 ℃ or more. Subsequently, a buried oxide film 37 is formed on the first nitride film 36 to fill the trench 33. In this case, a high density plasma (HDP) oxide film is used as the buried oxide film 37.

3C, the resultant CMP is formed until the pad nitride layer 32 is exposed to form the device isolation layer 37a. In this case, reference numerals 35a and 36a, which are not described in FIG. 3C, respectively indicate the TEOS oxide film and the first nitride film remaining after the CMP.

Subsequently, as shown in FIG. 3D, the pad nitride film is removed and a portion of the first nitride film remaining after the CMP is etched. In this case, the first nitride film is wet-etched by 800 mm thick. Here, the TEOS oxide layer 35a prevents excessive etching to the active region when wet etching the first nitride layer. Meanwhile, reference numeral 36b, which is not described in FIG. 3D, indicates the first nitride film remaining after etching.

Subsequently, as shown in FIG. 3E, the resultant substrate is cleaned to remove the pad oxide film, and at the same time, the portion of the TEOS oxide film adjacent to the upper edge portion of the device isolation film 37a is removed. At this time, the cleaning process is carried out for 35 seconds using HF solution. Meanwhile, reference numeral 35b, which is not described in FIG. 3E, shows the TEOS oxide film remaining after the cleaning process.

Next, as shown in FIG. 3F, a tunnel oxide film 38 is formed on the resultant silicon substrate 30, and then a polysilicon film 39 and a hard mask are formed on the active region of the substrate resultant. A Floating Gate 41 having a structure in which a Mask film 40 is sequentially stacked is formed. Subsequently, a second nitride film 42, which is a nitride film for spacers, is formed on the entire surface of the substrate including the floating gate 41.

Thereafter, as illustrated in FIG. 3G, the second nitride layer is etched to form first spacers 42a on both sidewalls of the floating gate 41, and at the same time, the etching is performed on the upper sidewalls of the device isolation layer 37a. After that, a second spacer 42b connected to the remaining first nitride layer 36b is formed. In this case, since the second spacer 42b is connected to and fixed to the first nitride film 36b remaining after the etching, the second spacer 42b does not fall off by a subsequent cleaning process.

As described above, according to the present invention, a nitride film is interposed between the device isolation film and the substrate so that the nitride film for the spacer of the floating gate remaining on the upper sidewall of the device isolation film during the subsequent etching process of the nitride film for the spacer of the floating gate is performed. It is connected and fixed by a nitride film interposed between the separator and the substrate. Therefore, the spacer nitride film of the floating gate remaining on the upper sidewall of the device isolation film can be prevented from coming off by a subsequent cleaning process to contaminate the active region.                     

As a result, the present invention can prevent deterioration of the characteristics of the device.

Claims (5)

Providing a silicon substrate in which an active region and a field region are defined; Sequentially forming a pad oxide film and a pad nitride film exposing the field region on the silicon substrate; Etching a field region of the exposed substrate to form a trench; Sequentially forming an oxide film and a first nitride film on the trench formed substrate resultant; Forming a buried oxide film to fill the trench on the first nitride film; Forming a device isolation film by CMPing the buried oxide film until the pad nitride film is exposed; Removing the pad nitride film; Removing the pad oxide film; Forming a floating gate on an active region of the substrate; Forming a second nitride film on an entire surface of the substrate including the floating gate; And Etching the second nitride film to form first spacers on both sidewalls of the floating gate, and forming a second spacer connected to the remaining first nitride film on the upper sidewall of the device isolation layer. A semiconductor device manufacturing method characterized by the above-mentioned. The method of claim 1, wherein the oxide film is formed of a TEOS oxide film. delete delete The method of claim 1, wherein the first nitride film is wet-etched by a thickness of about 800 kPa during the pad nitride film removing step.

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