KR100888201B1 - Method of forming multiple gate oxide - Google Patents

Abstract

SUMMARY OF THE INVENTION The present invention is to provide a method for forming a multi-gate oxide film suitable for forming various devices having different gate oxide film thicknesses in one chip through a simple process while overcoming the limitations of the dual gate oxide film technology by the plasma nitridation method. The method of forming a multi-gate oxide film of the method comprises the steps of forming an oxynitride on a semiconductor substrate divided into a first region, a second region, and a third region, and reducing an ion or an oxidation rate for increasing an oxidation rate in a first region of the semiconductor substrate. Implanting ions of ions, selectively removing oxynitride on the first region and the second region of the semiconductor substrate to leave the oxynitride in only the third region, and the first region, the first region Forming a gate oxide film having a different thickness by oxidizing the semiconductor substrate of the second region and the third region And a system.

Multi-gate oxide film, dual gate oxide film, triple gate oxide film, ion for increasing oxidation rate, ion for decreasing oxidation rate, oxynitride

Description

Method of forming multiple gate oxide             

1A to 1C are cross-sectional views illustrating a method of forming a multi-gate oxide film according to the prior art;

2A through 2D are cross-sectional views illustrating a method of forming a multi-gate oxide film according to a first embodiment of the present invention;

3A to 3D are cross-sectional views illustrating a method of forming a multi-gate oxide film according to a second embodiment of the present invention;

4A to 4E are cross-sectional views illustrating a method of forming a multi-gate oxide film according to a third embodiment of the present invention;

FIG. 5 illustrates a semiconductor substrate in which various devices are on-chip by applying a multi-gate oxide film according to the first embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

31 semiconductor substrate 32 oxynitride

33: first masking layer 34: ion for increasing the oxidation rate

35 ion implantation layer 36 second mask layer

37a: first gate oxide film 37b: second gate oxide film                 

37c: third gate oxide film

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to semiconductor manufacturing technology, and more particularly, to a method of forming a multiple gate oxide.

Recently, in order to satisfy the requirements of various products, SOC (System On Chip) technology in which devices for various purposes are formed in one chip has been studied. In such SOC technology, the operating voltage of each device is different, and the technology necessary for the process is a technique of forming a gate oxide film having a different thickness from each other. In other words, a thick gate oxide film is required for a high voltage device that requires high voltage, and a thin gate oxide film should be used in a low voltage device where the operation speed of the device is important.

Developed by these requirements, dual gate oxide technology.

Thus, by controlling the thickness of the gate oxide film according to the purpose of the device divided into three regions in one chip rather than a process having a different thickness of the two devices, it is possible to manufacture a variety of products as well as design and margin of the device. For example, a gate oxide film may be formed in three regions of a high voltage device, a low voltage device, and an intermediate voltage device according to the purpose.                         

Accordingly, there is a need for a multiple gate oxide technology having a different thickness of the gate oxide film for each device.

1A to 1C are cross-sectional views illustrating a method of forming a multi-gate oxide film according to the prior art.

As shown in FIG. 1A, after the resist pattern 12 is formed on the substrate 10 to expose a portion 16 of the substrate 10, the substrate may be formed using high density plasma nitridation. An oxynitride layer or thin nitride layer 18 is formed on the exposed surface of 10).

As shown in FIG. 1B, the resist pattern 12 is removed.

As shown in FIG. 1C, an oxidation process is performed to form a dual gate oxide film of a thick silicon oxide film 20a and a thin silicon oxide film 20b on the surface of the substrate 10.

At this time, oxidation is delayed by the nitride layer 18 to form a thin silicon oxide film 20b on the surface 16 of the substrate 10 on which the nitride layer 18 is formed, and the nitride layer 18 does not exist. A thick silicon oxide film 20a is formed on the surface 14 of the substrate.

In the above-described prior art, since the surface of the substrate 10 is selectively nitrided, only a dual gate oxide film may be formed, and a process may be complicated to apply the same to a multi-gate oxide film.

In addition, by controlling the thickness of the gate oxide film for each purpose in the device divided into three regions within one chip, not only the design and the margin of the device can be manufactured, but also a wider range of products can be manufactured. There is this. It is also essential to achieve symmetric threshold voltages in nMOSFETs and pMOSFETs for high performance and low voltage operation, but in p ⁺ polysilicon gate electrodes of pMOSFETs with thin gate oxides. Since boron penetration is a major problem, there is no multi-gate oxide technology for this.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems of the prior art, and is suitable for forming a plurality of devices having different gate oxide film thicknesses in one chip through a simple process while overcoming the limitation of the dual gate oxide film technology by the nitriding method. It is an object of the present invention to provide a method for forming a multi-gate oxide film.

In the method of forming the multi-gate oxide film of the present invention for achieving the above object, forming an oxynitride on a semiconductor substrate divided into a first region, a second region and a third region, the first region of the semiconductor substrate Implanting ions for controlling oxidation rate, selectively removing oxynitride on the first region and the second region of the semiconductor substrate, and leaving the oxynitride in only the third region; and And oxidizing the semiconductor substrate of the second region and the third region to form a gate oxide film having a different thickness, wherein the ion implantation of the oxidation rate control ion includes: Or ion implanting ions for increasing the oxidation rate, and implanting ions for increasing the oxidation rate is O ₂ , Si, Ge, or Ar. And ion implantation of the selected one at a dose of 1 × 10 ¹⁴ cm ^{-2 to} 1 × 10 ¹⁵ cm ^-2 and an ion implantation energy of 1 keV to ²⁰ keV. Is characterized in that N or N ₂ is ion-implanted at a dose of 1 × 10 ¹⁴ cm ^{−2 to} 1 × 10 ¹⁵ cm ^-2 and an ion implantation energy of 1 keV to ²⁰ keV.

In addition, the method of forming a multi-gate oxide film according to the present invention comprises the steps of forming an oxynitride on a semiconductor substrate divided into a first region, a second region, a third region and a fourth region, in the first region of the semiconductor substrate. Ion implanting ions for increasing the oxidation rate, ion implanting ions for reducing the oxidation rate in the second region, selectively oxynitride on the first region, the second region and the third region of the semiconductor substrate Removing the oxynitride to leave only the fourth region, and oxidizing the semiconductor substrates of the first region, the second region, the third region, and the fourth region to form gate oxide films having different thicknesses. Characterized in that it comprises a.

Hereinafter, the most preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the technical idea of the present invention. .

2A to 2D are cross-sectional views illustrating a method of forming a multi-gate oxide film according to a first embodiment of the present invention.

As shown in FIG. 2A, the oxynitride 32 is 10 Å to 200 Å thickness on the semiconductor substrate 31 divided into the first region I, the second region II, and the third region III. Form. For example, oxynitride 32 is formed by annealing or direct oxidation in an atmosphere selected from the group consisting of NO, N ₂ O, NH ₃ , ND ₃ (D is deuterium) and nitrogen radicals, At this time, the annealing and oxidation proceed for 1 to 60 minutes at 300 ° C to 900 ° C. For example, after the oxide film is grown on the semiconductor substrate 31 through an oxidation process, it is annealed in an atmosphere selected from the group consisting of NO, N ₂ O, NH ₃ , ND ₃ (D is deuterium) and nitrogen radicals. Or by direct oxidation to form oxynitride 32. At this time, the nitrogen concentration in the oxynitride 32 is 2% to 20%, and such nitrogen is accumulated up at the interface with the semiconductor substrate 31.

As shown in FIG. 2B, a photosensitive film is coated on the oxynitride 32 and patterned by exposure and development to open the first region I and the remaining second region II and third region III. A covering first masking layer 33 is formed.

Next, using the first masking layer 33 as an ion implantation mask, ions 34 for increasing the oxidation rate are implanted into the exposed first region (I). In this case, as the ion 34 for increasing the oxidation rate, one selected from O ₂ , Si, Ge, or Ar is used. Here, the source of Si and Ge is SiH ₄ , SiF ₄ , GeH ₄ , GeF ₄ , and the dose of these ions 34 is 1 × 10 ¹⁴ cm ^{−2 to} 1 × 10 ¹⁵ cm ^-2 , and ion implantation is performed. The energy ranges from 1 keV to 20 keV.

The ion implantation layer 35 having a predetermined depth distribution on the surface of the first region I of the semiconductor substrate 31 under the oxynitride 32 through ion implantation of the oxidation rate increasing ion 34 as described above. Is formed. In addition, since the oxynitride 32 inhibits the surface of the semiconductor substrate 31 from being damaged during the ion implantation of the ions 34 for increasing the oxidation rate, the oxynitride 32 is a sacrifice applied during the ion implantation. It can take the role of an oxide (screen oxide) to eliminate the need for a separate sacrificial oxide process.

As shown in FIG. 2C, the first masking layer 33 is removed. In this case, the first masking layer 33 may be removed using a dry etching method using an oxygen plasma (O ₂ plasma), a wet etching method using H ₂ SO ₄ , or an etching method using a thinner.

Next, a photosensitive film is applied again and patterned by exposure and development to form a second masking layer 36 covering the third region III and opening the first region I and the second region II.

Next, the oxynitride 32 of the first region I and the second region II exposed by the second masking layer 36 is removed through a wet dip out. In this case, the wet chemical used in the wet deep out uses a hydrofluoric acid (HF) series or a buffered oxide etchant (BOE) series.

As shown in FIG. 2D, the second masking layer 36 is removed. In this case, the second masking layer 36 may be removed by using a dry etching method using an oxygen plasma (O ₂ plasma), a wet etching method using H ₂ SO ₄ , or an etching method using a thinner.

As described above, after the removal of the second masking layer 36, the oxynitride is removed from the semiconductor substrate 31 of the first region (I) to expose the ion implantation layer 35 and the second region (II). The oxynitride is removed and exposed to the semiconductor substrate 31 of (), and the oxynitride 32 remains on the semiconductor substrate 31 of the third region (III).

In this way, each semiconductor substrate 31 having different surface characteristics is oxidized. At this time, in the first region (I) in which the ion implantation layer 35 into which the ion for increasing the oxidation rate is injected is exposed, the first gate oxide layer 37a having the highest thickness is formed at the fastest rate during oxidation, and a semiconductor is formed. In the second region (II) in which only the substrate 31 is exposed, a second gate oxide film 37b having a medium thickness is formed, and in the third region (III) in which the oxynitride 32 remains, the third having the thinnest thickness A gate oxide film 37c is formed.

The reason why the third gate oxide film 37c formed in the third region III is the thinnest is that the nitrogen atoms contained in the oxynitride 32 retard the oxidation rate. The third gate oxide film 37c is re-oxidized oxynitride.

Therefore, the first gate oxide film 37a having the thickest thickness, the second gate oxide film 37b having a medium thickness thinner than the first gate oxide film 37a, and the first and second gate oxide films on one semiconductor substrate 31 are thus provided. A triple gate oxide film of the third gate oxide film 37c that is thinner than the thicknesses 37a and 37b may be formed.

3A to 3D are cross-sectional views illustrating a method of forming a multi-gate oxide film according to a second embodiment of the present invention.

As shown in FIG. 3A, the oxynitride 42 is 10 Å to 200 된 thickness on the semiconductor substrate 41 divided into the first region I, the second region II, and the third region III. Form. For example, the oxynitride 42 is formed by annealing or directly oxidizing in an atmosphere selected from the group consisting of NO, N ₂ O, NH ₃ , ND ₃ (D is deuterium) and nitrogen radicals, At this time, the annealing and oxidation proceed for 1 to 60 minutes at 300 ° C to 900 ° C. For example, after the oxide film is grown on the semiconductor substrate 41 through an oxidation process, it is annealed in an atmosphere selected from the group consisting of NO, N ₂ O, NH ₃ , ND ₃ (D is deuterium) and nitrogen radicals. Or by direct oxidation to form oxynitride 42. At this time, the nitrogen concentration in the oxynitride 42 is 2% to 20%, and such nitrogen is accumulated at the interface with the semiconductor substrate 31.

As shown in FIG. 3B, a photosensitive film is coated on the oxynitride 42 and patterned by exposure and development to open the first region I and the remaining second region II and third region III. A covering first masking layer 43 is formed.

Next, using the first masking layer 43 as an ion implantation mask, ions 44 for reducing the oxidation rate are implanted into the exposed first region (I). At this time, N or N ₂ is used as the ion 44 for reducing the oxidation rate. Here, the dose of the oxidation rate reducing ions 44 is 1 × 10 ¹⁴ cm ^{−2 to} 1 × 10 ¹⁵ cm ⁻² , and the ion implantation energy is in the range of 1 keV to 20 keV.

The ion implantation layer 45 having a predetermined depth distribution on the surface of the first region I of the semiconductor substrate 41 under the oxynitride 42 through the ion implantation of the oxidation rate increasing ion 44 as described above. Is formed. In addition, since the oxynitride 42 inhibits the surface of the semiconductor substrate 41 from being damaged during ion implantation of the oxidation rate reducing ion 44, the oxynitride 42 is a sacrifice applied during ion implantation in general. It can take the role of an oxide (screen oxide) to eliminate the need for a separate sacrificial oxide process.

As shown in FIG. 3C, the first masking layer 43 is removed. In this case, the first masking layer 43 may be removed by using a dry etching method using an oxygen plasma (O ₂ plasma), a wet etching method using H ₂ SO ₄ , or an etching method using a thinner.

Next, a photosensitive film is applied again and patterned by exposure and development to form a second masking layer 46 covering the third region III and opening the first region I and the second region II.

Next, the oxynitride 42 of the first region I and the second region II exposed by the second masking layer 46 is removed through a wet dip out. In this case, the wet chemical used in the wet deep out uses a hydrofluoric acid (HF) series or a buffered oxide etchant (BOE) series.

As shown in FIG. 3D, the second masking layer 46 is removed. In this case, the second masking layer 46 may be removed by using a dry etching method using an oxygen plasma (O ₂ plasma), a wet etching method using H ₂ SO ₄ , or an etching method using a thinner.

As described above, after the removal of the second masking layer 46, the oxynitride is removed from the semiconductor substrate 41 of the first region (I) to expose the ion implantation layer 45, and the second region (II). The oxynitride is removed and exposed to the semiconductor substrate 41 of), and the oxynitride 42 remains on the semiconductor substrate 41 of the third region (III).

In this manner, each semiconductor substrate 41 having different surface characteristics is oxidized. At this time, in the first region (I) in which the ion implantation layer 45 into which the ion for reducing the oxidation rate is injected is exposed, the first gate oxide layer 47a having the thinnest thickness is formed during the oxidation, and the semiconductor is formed. In the second region (II) where only the substrate 41 is exposed, the second gate oxide film 37b is formed with the fastest oxidation rate, and the middle region is formed in the third region (III) where the oxynitride 42 remains. A third gate oxide film 47c is formed.

The reason why the first gate oxide film 47a formed in the first region I is the thinnest is that the nitrogen atoms contained in the ion implantation layer 45 delay the oxidation rate. Even if the third gate oxide film 47c has the same oxidation rate as the third gate oxide film 47c, the third gate oxide film 47c is reoxidized to the oxynitride 42. It is thinner than the three-gate oxide film 47c.

Therefore, the thickness of the thinnest first gate oxide film 47a, the thickest second gate oxide film 47b, the first gate oxide film 47a, and the second gate oxide film 47b on the semiconductor substrate 41 is determined. A triple gate oxide film of the third gate oxide film 47c having can be formed.

4A to 4E are cross-sectional views illustrating a method of forming a multi-gate oxide film according to a third embodiment of the present invention.

As shown in FIG. 4A, an oxynitride 52 is formed on a semiconductor substrate 51 divided into a first region I, a second region II, a third region III, and a fourth region IV. ) Is formed to a thickness of 10Å to 200Å. For example, oxynitride 52 is formed by annealing or direct oxidation in an atmosphere selected from the group consisting of NO, N ₂ O, NH ₃ , ND ₃ (D is deuterium) and nitrogen radicals, At this time, the annealing and oxidation proceed for 1 to 60 minutes at 300 ° C to 900 ° C. For example, after the oxide film is grown on the semiconductor substrate 51 through an oxidation process, it is annealed in an atmosphere selected from the group consisting of NO, N ₂ O, NH ₃ , ND ₃ (D is deuterium) and nitrogen radicals. Or directly oxidized to form oxynitride 52. At this time, the nitrogen concentration in the oxynitride 52 is 2% to 20%, and such nitrogen is accumulated at the interface with the semiconductor substrate 51.

As shown in FIG. 4B, a photosensitive film is coated on the oxynitride 52 and patterned by exposure and development to open the first region I and the remaining second region II, third region III and The first masking layer 53a covering the fourth region IV is formed.

Next, ions 54a for increasing the oxidation rate are implanted into the exposed first region I by using the first masking layer 53a as an ion implantation mask. In this case, one selected from O ₂ , Si, Ge, or Ar is used as the ion rate 54a for increasing the oxidation rate. Here, the source of Si and Ge is SiH ₄ , SiF ₄ , GeH ₄ , GeF ₄ , and the dose of these ions 54a for increasing the oxidation rate is 1 × 10 ¹⁴ cm ^{-2 to} 1 × 10 ¹⁵ cm ^-2 . The ion implantation energy is in the range of 1 keV to 20 keV.

The first ion implantation layer having a predetermined depth distribution on the surface of the first region (I) of the semiconductor substrate 51 under the oxynitride 52 through the ion implantation of the oxidation rate increasing ion 54a as described above ( 55a) is formed.

As shown in FIG. 4C, after removing the first masking layer 53a, a photoresist film is applied on the oxynitride 52 and patterned by exposure and development to open the second region II and cover the remaining regions. The second masking layer 53b is formed.

Next, the ionization rate reduction ion 54b is implanted into the exposed second region II using the second masking layer 53b as an ion implantation mask. At this time, N or N ₂ is used as the ion reduction rate 54b. Here, the dose of the oxidation rate reducing ions 54b is 1 × 10 ¹⁴ cm ^{−2 to} 1 × 10 ¹⁵ cm ⁻² , and the ion implantation energy is in the range of 1 keV to 20 keV.

The second ion implantation layer having a predetermined depth distribution on the surface of the second region (II) of the semiconductor substrate 51 under the oxynitride 52 through the ion implantation of the oxidation rate reducing ion 54b as described above ( 55b) is formed.

As shown in FIG. 4D, the second masking layer 53b is removed. In this case, the second masking layer 53b may be removed by using a dry etching method using an oxygen plasma (O ₂ plasma), a wet etching method using H ₂ SO ₄ , or an etching method using a thinner.

Next, a photosensitive film is applied again and patterned by exposure and development to form a third masking layer 56 covering the fourth region IV and opening the remaining regions.

Next, the oxynitride 52 of the remaining regions I, II, and III exposed by the third masking layer 56 is removed through a wet dip out. In this case, the wet chemical used in the wet deep out uses a hydrofluoric acid (HF) series or a buffered oxide etchant (BOE) series.

As shown in FIG. 4E, the third masking layer 56 is removed. In this case, the third masking layer 56 may be removed by using a dry etching method using an oxygen plasma (O ₂ plasma), a wet etching method using H ₂ SO ₄ , or an etching method using a thinner.

As described above, after the removal of the third masking layer 56, the oxynitride is removed from the semiconductor substrate 51 of the first region (I) to expose the first ion implantation layer 55a and the first region. The oxynitride is removed from the semiconductor substrate 51 of (I) to expose the second ion implantation layer 55b, and the semiconductor substrate 51 of the third region (III) is exposed to remove the oxynitride. The oxynitride 52 remains on the semiconductor substrate 51 of the fourth region IV.

In this manner, the semiconductor substrates 51 having different surface characteristics are oxidized. At this time, in the first region (I) in which the first ion implantation layer 55a into which the ion for increasing the oxidation rate is implanted is exposed, the thickest first gate oxide film 57a is formed at the highest rate during oxidation, and the oxidation rate is In the second region (II) in which the second ion implantation layer 55b into which the reducing ion is implanted is exposed, the second gate oxide film 57b is formed to have the smallest thickness during oxidation. In the third region (III) where only the semiconductor substrate 51 is exposed, a third gate oxide film 57c thicker than the second gate oxide film 57b and thinner than the first gate oxide film 57a is formed, and oxynitride ( In the fourth region (IV) where 52 remains, a fourth gate oxide film 57d thinner than the third gate oxide film and thicker than the second gate oxide film is formed.

The reason why the first gate oxide film 57a formed in the first region I is thickest is that the ions for oxidation rate contained in the first ion implantation layer 55a increase the oxidation rate. The reason that the second gate oxide film 57b is the thinnest is that the nitrogen atoms contained in the second ion implantation layer 55b delay the oxidation rate. Even though the fourth gate oxide film 57d has the same oxidation rate as that of the fourth gate oxide film 57d, the second gate oxide film 57b is formed by reoxidizing the oxynitride 52. It is thinner than the four-gate oxide film 57d.

As a result, four gate oxide films having different thicknesses may be formed on the semiconductor substrate 51.

FIG. 5 illustrates a semiconductor substrate in which various devices are on-chip by applying a triple gate oxide film according to a first embodiment of the present invention.

As shown in FIG. 5, these MOSFETs are separated on a single semiconductor substrate 60 on which a low voltage (LV) pMOSFET, a medium voltage (MV) nMOSFET and a high voltage (HV) nMOSFET are to be formed. The field oxide film 61 is formed, and each MOSFET is formed with a gate oxide film having a different thickness.

First, the thickest first oxide film 62a is formed in the high voltage nMOSFET by implanting ions for increasing the oxidation rate, and then oxidizes the second gate oxide film in which the surface of the semiconductor substrate 60 is simply oxidized. 62b is formed, and finally, in the low voltage pMOSFET, the thinnest third gate oxide film 62c in which oxynitride is reoxidized is formed.

Then, on the first gate oxide film 62a and the second gate oxide film 62b, a stacked film of polysilicon n ⁺ polysilicon gate electrodes 63 and a hard mask 64 implanted with n-type dopants is formed, respectively, and a pMOSFET. On the third gate oxide film 62c, a laminated film of a polysilicon p ⁺ polysilicon gate electrode 65 and a hard mask 64 implanted with a p-type dopant is formed. The spacers 66 are formed on both sidewalls of the n ⁺ polysilicon gate electrode 63 and the p ⁺ polysilicon gate electrode 65.

Herein, the n ⁺ polysilicon gate electrode 63 and the p ⁺ polysilicon gate electrode 65 are doped with dopants in order to adjust the work function, and in addition to the polysilicon gate electrode, TiN, A poly metal gate electrode in which metal films such as WN, TiAlN, TiSiN, TaN, TaSiN, MoN, W, and MO are stacked may be used.

In particular, oxynitride reoxidized only in the pMOSFET can be used to prevent boron from penetrating into the semiconductor substrate 60 from the p ⁺ polysilicon gate electrode 65. If oxynitride is also used for the nMOSFET, the performance of the device is deteriorated by the nitrogen atom, but the present invention can form oxynitride only in the selective region. As a result, a symmetrical threshold voltage CMOSFET can be formed, so that a high performance and low voltage operation SOC can be realized.

As described above, the present invention is not limited to the above-described embodiments and the accompanying drawings, and the present invention may be variously substituted, modified, and changed without departing from the spirit of the present invention. It will be apparent to those of ordinary skill in Esau.

As described above, the present invention can form a gate oxide film having various thicknesses in one chip using oxynitride, thereby widening the margin of design, device, and process, and manufacturing various products.

Claims (9)

Forming oxynitride on a semiconductor substrate divided into a first region, a second region, and a third region; Implanting ions for controlling the oxidation rate into the first region of the semiconductor substrate; Selectively removing oxynitride on the first region and the second region of the semiconductor substrate to leave the oxynitride only in the third region; And Oxidizing the semiconductor substrates of the first region, the second region, and the third region to form gate oxide films having different thicknesses; Method of forming a multi-gate oxide film comprising a. The method of claim 1, Injecting the ion for adjusting the oxidation rate, A method of forming a multi-gate oxide film, characterized by ion implantation of ions for decreasing oxidation rate or ions for increasing oxidation rate. The method of claim 2, The ion implantation of the ion for increasing the oxidation rate, Ion implantation of one selected from O ₂ , Si, Ge or Ar with a dose of 1 × 10 ¹⁴ cm ^{-2 to} 1 × 10 ¹⁵ cm ^-2 and ion implantation energy of 1keV to 20keV Forming method. The method of claim 2, Ion implantation of the ion for reducing the oxidation rate, A method of forming a multi-gate oxide film comprising ion implantation of N or N ₂ at a dose of 1 × 10 ¹⁴ cm ^{−2 to} 1 × 10 ¹⁵ cm ⁻² and ion implantation energy of 1 keV to ²⁰ keV. The method of claim 1, Residing the oxynitride only in the third region, Method of forming a multi-gate oxide film, characterized in that the wet dip out using a hydrofluoric acid or BOE-based wet chemical. Forming oxynitride on a semiconductor substrate divided into a first region, a second region, a third region, and a fourth region; Implanting ions for increasing the oxidation rate into the first region of the semiconductor substrate; Implanting ions for reducing the oxidation rate into the second region Selectively removing oxynitride on the first region, the second region and the third region of the semiconductor substrate to leave the oxynitride only in the fourth region; And Oxidizing the semiconductor substrates of the first region, the second region, the third region, and the fourth region to form gate oxide films having different thicknesses. Method of forming a multi-gate oxide film comprising a. The method of claim 6, Injecting the ion for increasing the oxidation rate, A multi-gate oxide film formed by ion implantation of one selected from O ₂ , Si, Ge, or Ar with a dose of 1 × 10 ¹⁴ cm ^{-2 to} 1 × 10 ¹⁵ cm ^-2 and ion implantation energy of 1 keV to ²⁰ keV Method of formation. The method of claim 6, Injecting the ion for reducing the oxidation rate, A method of forming a multi-gate oxide film, wherein N or N ₂ is ion-implanted at a dose of 1 × 10 ¹⁴ cm ^{−2 to} 1 × 10 ¹⁵ cm ⁻² and an ion implantation energy of 1 keV to ²⁰ keV. The method of claim 6, Residing the oxynitride only in the fourth region, Method of forming a multi-gate oxide film, characterized in that the wet dip out using a hydrofluoric acid or BOE-based wet chemical.

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