KR100880747B1 - Substrate processing method and substrate processing apparatus - Google Patents

Abstract

It is an object of the present invention to provide a substrate processing method capable of selectively removing a nitride film, and to provide a wafer W having a thermal oxide film 51 made of SiO ₂ and a silicon nitride film 52 made of SiN. In this case, the oxygen plasma into which the oxygen gas has been plasma-formed is brought into contact with the silicon nitride film 52 to change the silicon nitride film 52 into the silicon monoxide film 54, and the HF gas is supplied toward the silicon monoxide film 54. Thereby selectively etching the silicon monoxide film 54 with hydrofluoric acid generated from the HF gas.

Description

Substrate processing method and substrate processing apparatus {SUBSTRATE PROCESSING METHOD AND SUBSTRATE PROCESSING APPARATUS}

BRIEF DESCRIPTION OF THE DRAWINGS It is a top view which shows schematic structure of the substrate processing system which performs the substrate processing method which concerns on 1st Embodiment of this invention.

FIG. 2 is a cross-sectional view of the second process module in FIG. 1, FIG. 2A is a cross-sectional view taken along the line II in FIG. 1, and FIG. 2B is a part A in FIG. 2A. It is an enlarged view.

3 is a flowchart showing a substrate processing method according to the first embodiment of the present invention.

It is process drawing which shows the substrate processing method which concerns on 2nd Embodiment of this invention.

Explanation of symbols for main parts of the drawings

10: Substrate Processing System 11: 1st Process Easy

12: second process easy 25: first process module

34: second process module 38: chamber

39: mounting table 40: shower head

43: gas supply part 50, 60: silicon base material

51, 61: thermal oxide film 52, 63: silicon nitride film

53: active species 54, 64: silicon monoxide film

62: gate electrode

TECHNICAL FIELD This invention relates to a substrate processing method and a substrate processing apparatus. Specifically, It is related with the substrate processing method which processes the board | substrate with which the thermal oxidation film and the silicon nitride film were formed.

BACKGROUND ART A wafer (substrate) for a semiconductor device having a thermal oxide film formed by a thermal oxidation process, for example, a silicon oxide film and a silicon nitride film formed by a CVD process or the like is known. The silicon nitride film is used as an antireflection (BARC) film or a spacer separating the gate and the source / drain. In addition, the thermal oxide film constitutes a gate oxide film.

As an etching method of a silicon nitride film, a compound gas containing fluorine as a constituent element and a carbon as a constituent element, such as HF gas, is converted into a plasma, and the plasma compounded compound gas is reacted with carbon to produce a chemical species ( A method of forming a radical) and etching a silicon nitride film with a chemical species is known (see Patent Document 1, for example).

[Patent Document 1] Japanese Patent Publication No. 2003-264183

However, the chemical species also etches the thermal oxide film. For example, in a wafer in which a silicon oxide film (thermal oxide film) is formed as a gate insulating film on a silicon substrate, and a silicon nitride film as an antireflection film is formed on the silicon oxide film, not only the silicon nitride film but also the above etching method. Even the silicon oxide film is etched. In general, since the gate insulating film is formed thinner than the antireflection film, the silicon oxide film is removed before the silicon nitride film is removed, and as a result, the silicon substrate is also damaged (etched).

An object of the present invention is to provide a substrate processing method and a substrate processing apparatus capable of selectively removing a nitride film.

In order to achieve the above object, the substrate processing method according to claim 1 is a substrate processing method for processing a substrate having a thermal oxide film and a nitride film formed by thermal oxidation treatment, wherein the plasma containing oxygen is brought into contact with the substrate. And a HF gas supply step of supplying an HF gas toward the substrate to which the plasma containing oxygen is in contact.

The substrate processing method of Claim 2 is a substrate processing method of Claim 1 WHEREIN: The said board | substrate is provided with the convex conductive part which protrudes on the said thermal oxidation film, The said nitride film covers the side surface and top surface of the said conductive part. In the oxygen plasma contacting step, the active species in the plasma containing oxygen moves in parallel with the side surface to contact the nitride film.

The substrate processing method of claim 3 is the substrate processing method of claim 2, wherein the active species contains at least a cation.

The substrate processing method according to claim 4 has the selective oxidation step of selectively oxidizing the flat portion of the nitride film in the substrate processing method according to claim 2 or 3.

The substrate processing method according to claim 5 is the substrate processing method according to claim 1, wherein the substrate has a convex conductive portion projecting vertically from the surface of the substrate on the thermal oxide film, and the nitride film has a side surface of the conductive portion and Covering the top surface, in the oxygen plasma contacting step, the active species in the plasma containing oxygen moves to be substantially perpendicular to the surface of the substrate to be in contact with the nitride film.

The substrate processing method according to claim 6 has the selective oxidation step of selectively oxidizing the flat portion of the nitride film in the substrate processing method according to claim 5.

In order to achieve the above object, the substrate processing apparatus according to claim 7 is a substrate processing apparatus for processing a substrate having a thermal oxide film and a nitride film formed by thermal oxidation treatment, the substrate processing apparatus comprising: oxygen contacting a plasma containing oxygen to the substrate And a plasma contact device and an HF gas supply device for supplying an HF gas toward the substrate in contact with the plasma containing oxygen.

Best Mode for Carrying Out the Invention

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described, referring drawings.

First, the substrate processing system which performs the substrate processing method which concerns on 1st Embodiment of this invention is demonstrated.

FIG. 1: is a top view which shows schematic structure of the substrate processing system which performs the substrate processing method which concerns on this embodiment.

In FIG. 1, the substrate processing system 10 (substrate processing apparatus) is the 1st process easy to perform a plasma process on the wafer (henceforth a "wafer") W (substrate) for semiconductor devices ( 11) The second process ship 12, which is disposed in parallel with the first process ship 11 and performs a selective etching process, which will be described later, on the wafer W subjected to the plasma treatment in the first process ship 11. ), And a loader module 13 as a rectangular common transport chamber to which the first process ship 11 and the second process ship 12 are connected, respectively.

In addition to the first process ship 11 and the second process ship 12 described above, the loader module 13 includes a front opening Unified Pod (FOUP) 14 as a container for holding 25 wafers W. Measuring the surface states of the wafers W and the three pouf placing tables 15, the orienter 16 for prealigning the position of the wafer W carried out from the pouf 14, respectively. First and second IMS (Integrated Metrology System, Therma-Wave, Inc.) 17, 18 are connected.

The 1st process ship 11 and the 2nd process ship 12 are connected to the side wall which follows the longitudinal direction of the loader module 13, and are equipped with the three poop mounts 15 with the loader module 13 interposed. Are arranged to face each other, the orienter 16 is arranged at one end along the longitudinal direction of the loader module 13, and the first IMS 17 is arranged at the other end along the longitudinal direction of the loader module 13, and 2 IMS 18 is arranged in parallel with three pouf mounts 15.

The loader module 13 is a scalar type dual arm type transfer arm mechanism 19 for carrying the wafer W disposed therein, and a wafer W disposed on the side wall so as to correspond to each pouf placing table 15. It has three load ports 20 as an inlet of (). The transfer arm mechanism 19 takes out the wafer W from the pouf 14 mounted on the poop mounting table 15 via the load port 20, and takes out the taken out wafer W in a first process ( 11) It carries in and out to the 2nd process ship 12, the orienter 16, the 1st IMS 17, and the 2nd IMS 18. FIG.

The first IMS 17 is a monitor of an optical system, and has a stage 21 on which the wafer W loaded is placed, and an optical sensor 22 directed to the wafer W placed on the stage 21. The surface shape of the wafer W, for example, the film thickness of the polysilicon film, the CD (Critical Dimension) values of the wiring grooves and the gate electrodes are measured. The second IMS 18 is also an optical monitor, and has a stage 23 and an optical sensor 24 similarly to the first IMS 17.

The first process ship 11 supplies a wafer W to a first process module 25 (oxygen plasma contact device) that performs a plasma treatment on the wafer W, and to the first process module 25. It has the 1st load lock module 27 which accommodates the 1st conveyance arm 26 of the receiving link type single pick type.

The first process module 25 has a cylindrical processing chamber container (chamber) and an upper electrode and a lower electrode (not shown) disposed in the chamber, and the distance between the upper electrode and the lower electrode is a wafer ( W) is set at an appropriate interval for performing the plasma treatment. In addition, the lower electrode has an ESC 28 in its government which chucks the wafer W by a coulomb force or the like.

In the first process module 25, the oxygen gas is introduced into the chamber to generate an electric field between the upper electrode and the lower electrode to plasma the introduced oxygen gas to generate an oxygen plasma, and the active contained in the oxygen plasma. Species, specifically cations, are brought into contact with the wafer W to perform plasma treatment.

In the first process ship 11, the internal pressure of the loader module 13 is maintained at atmospheric pressure while the internal pressure of the first process module 25 is maintained in vacuum. Therefore, the 1st load lock module 27 is equipped with the vacuum gate valve 29 in the connection part with the 1st process module 25, and the standby gate valve 30 in the connection part with the loader module 13 is carried out. It is configured as a vacuum pre-conveying chamber whose internal pressure is adjustable.

Inside the first load lock module 27, a first conveyance arm 26 is provided in a substantially central portion, and the first buffer 31 is located closer to the first process module 25 than the first conveyance arm 26. ) Is installed, and a second buffer 32 is provided on the loader module 13 side than the first transfer arm 26. The 1st buffer 31 and the 2nd buffer 32 are arrange | positioned on the track | orbit which the support part (pick) 33 which supports the wafer W arrange | positioned at the front-end | tip part of the 1st conveyance arm 26 moves. By temporarily evacuating the plasma processed wafer W above the trajectory of the support 33, smooth replacement of the unprocessed wafer W and the processed wafer W in the first process module 25 can be achieved. Make it possible.

The 2nd process ship 12 contacts the 2nd process module 34 which performs the selective etching process mentioned later on the wafer W, and the said 2nd process module 34 via the vacuum gate valve 35. And a second load / lock module 37 incorporating a second transfer arm 36 of the link type single pick type, which transfers the wafer W to the second process module 34.

FIG. 2: is sectional drawing of the 2nd process module in FIG. 1, FIG. 2 (A) is sectional drawing along the line II in FIG. 1, and FIG. 2 (B) is A in FIG. It is an enlarged view of wealth.

In FIG. 2A, the second process module 34 includes a cylindrical processing chamber container (chamber) 38, a mounting table 39 of the wafer W disposed in the chamber 38, and a chamber ( Above the 38, the shower head 40 disposed to face the mounting table 39, a turbo molecular pump (TMP) 41 for exhausting gas, etc. in the chamber 38, and the chamber 38 and the TMP ( 41 has an Adaptive Pressure Control (APC) valve 42 as a variable butterfly valve disposed between 41 and controlling the pressure in the chamber 38.

The shower head 40 has a disk-shaped gas supply part 43 (HF gas supply device), and the gas supply part 43 has a buffer chamber 44. The buffer chamber 44 communicates with the chamber 38 through the gas vent 45.

The buffer chamber 44 in the gas supply part 43 of the shower head 40 is connected to the HF gas supply system (not shown). The HF gas supply system supplies HF gas to the buffer chamber 44. The supplied HF gas is supplied into the chamber 38 through the gas vent 45. The gas supply part 43 of the shower head 40 contains a heater (not shown), for example, a heating element. This heating element controls the temperature of the HF gas in the buffer chamber 44.

In the shower head 40, as shown in FIG. 2 (B), the opening part into the chamber 38 in the gas vent hole 45 is formed in the shape which the edge part spreads. As a result, the HF gas can be efficiently diffused into the chamber 38. In addition, since the gas vent hole 45 has a narrow cross section, the residue generated in the chamber 38 and the like are prevented from flowing back into the gas vent hole 45 and further into the buffer chamber 44.

In the second process module 34, the side wall of the chamber 38 contains a heater (not shown), for example, a heating element. Thereby, the atmospheric temperature in the chamber 38 can be set higher than normal temperature, and the removal by the hydrofluoric acid of the silicon monoxide film 54 mentioned later can be promoted. In addition, the heating element in the side wall prevents the residue generated during the removal by the hydrofluoric acid of the silicon monoxide film 54 from adhering to the inside of the side wall by heating the side wall.

The mounting table 39 has a refrigerant chamber (not shown) inside as a temperature control mechanism. The refrigerant chamber is supplied with a refrigerant having a predetermined temperature, for example, cooling water or garden liquid, and the temperature of the wafer W placed on the upper surface of the mounting table 39 is controlled by the temperature of the refrigerant.

Returning to FIG. 1, the 2nd rod lock module 37 has the conveyance chamber (chamber) 46 on the housing which incorporates the 2nd conveyance arm 36. As shown in FIG. In addition, the internal pressure of the loader module 13 is maintained at atmospheric pressure, while the internal pressure of the second process module 34 is maintained at or below atmospheric pressure, for example, almost vacuum. Therefore, the 2nd load lock module 37 is equipped with the vacuum gate valve 35 in the connection part with the 2nd process module 34, and the standby door valve 47 in the connection part with the loader module 13 is carried out. It is configured as a vacuum pre-conveying chamber whose internal pressure is adjustable.

Moreover, the substrate processing system 10 is equipped with the operation panel 48 arrange | positioned at the end in the longitudinal direction of the loader unit 13. The operation panel 48 has a display portion made of, for example, a liquid crystal display (LCD), and the display portion displays the operation status of each component of the substrate processing system 10.

By the way, in a wafer having a thermal oxide film formed by a thermal oxidation process and an oxide film containing impurities formed by a CVD process, a method of selectively etching an oxide film containing impurities, for example, HF gas or HF gas and H _A method of using a mixed gas of ₂ O gas without making it plasma is known (see, for example, Japanese Patent Application Laid-Open No. 194-181188).

Moreover, the present inventors conducted various experiments to increase the selectivity of the oxide film containing impurities to the thermal oxide film than the above method, and did not supply H ₂ O gas under an environment in which almost no H ₂ O existed. When only HF gas was supplied toward the wafer W, it was found that the selectivity of the oxide film containing impurities to the thermal oxidation film can be greatly increased.

Then, the present inventors earnestly studied the mechanism of realizing the high selectivity ratio, and inferred the hypothesis described below.

HF gas becomes hydrofluoric acid by combining with H ₂ O, and the hydrofluoric acid invades and removes the oxide film. Here, in an environment where H ₂ O is hardly present, in order for HF gas to be hydrofluoric acid, it is necessary to be combined with water (H ₂ O) molecules contained in the oxide film.

Since the oxide film containing an impurity is formed by vapor deposition such as a CVD process, the structure of the film is poor, and water molecules tend to adsorb. Therefore, water molecules are contained to some extent in the oxide film containing impurities. The HF gas that reaches the oxide film containing impurities combines with this water molecule to form hydrofluoric acid. This hydrofluoric acid then invades the oxide film containing impurities.

On the other hand, since the thermal oxidation film is formed by thermal oxidation treatment in an environment of 800 to 900 ° C, water molecules are not included at the time of film formation, and the structure of the film is also compact, so that water molecules are difficult to adsorb. Therefore, the thermal oxide film contains almost no water molecules. Even if the supplied HF gas reaches the thermal oxide film, it does not become hydrofluoric acid because no water molecules are present. As a result, the thermal oxide film does not invade.

As a result, when only HF gas is supplied toward the wafer W without supplying the H ₂ O gas in an environment in which almost no H ₂ O exists, the selectivity of the oxide film including impurities to the thermal oxide film is greatly increased. (Selective etching treatment).

In this embodiment, on the silicon substrate 50 as shown in Fig. 3A, a thermal oxide film 51 made of SiO ₂ formed by thermal oxidation treatment and a silicon nitride film made of SiN formed by CVD treatment In the wafer W on which (52) (nitride film) is stacked, the selective etching treatment with hydrofluoric acid described above is used to selectively remove the silicon nitride film 52. Specifically, after the silicon nitride film 52 on the wafer W is changed into an oxide film by an oxidation process, the above-described selective etching process with hydrofluoric acid is used.

Hereinafter, the oxidation process of the silicon nitride film 52 in this embodiment is demonstrated.

When the silicon nitride film 52 is brought into contact with active species 53 in an oxygen plasma (O ₂ plasma) generated from oxygen (O ₂ ) gas, for example, a cation (FIG. 3B), the silicon nitride film 52 SiN and the active species in the oxygen plasma cause a chemical reaction represented by the following formula,

2SiN + O ₂ → 2SiNO

SiNO is produced. Since SiNO is an unstable substance, as shown in the following formula, nitrogen is separated and sublimed,

2SiNO → 2SiO + N ₂ ↑

SiO (silicon monoxide) is produced. As a result, the silicon nitride film 52 is changed into a silicon monoxide film 54 made of SiO (Fig. 3 (C)). Since the silicon monoxide film 54 is formed by the CVD process and the silicon nitride film 52 whose film structure is sparse is changed, the structure of the silicon monoxide film 54 is also sparse. Therefore, the silicon monoxide film 54 contains water molecules to some extent. In this embodiment, the silicon monoxide film 54 is selectively etched using a selective etching process with hydrofluoric acid, and as a result, the silicon nitride film 52 is selectively removed.

Next, the substrate processing method which concerns on this embodiment is demonstrated. In the substrate processing method according to the present embodiment, the substrate processing system 10 of FIG. 1 executes.

First, a thermal oxide film 51 made of SiO ₂ is formed on the silicon substrate 50, and a wafer W on which the silicon nitride film 52 made of SiN is formed is prepared on the thermal oxide film 51. (FIG. 3 (A)). The wafer W is loaded into the chamber of the first process module 25 and placed on the ESC 28.

Next, oxygen gas is introduced into the chamber to generate an electric field between the upper electrode and the lower electrode to plasma the oxygen gas to generate active species 53 in the oxygen plasma, and nitrify the active species 53 in the oxygen plasma. The silicon film 52 is brought into contact (oxygen plasma contact step). At this time, the sheath 55 is generated parallel to the surface of the wafer W in a space near the surface of the wafer W due to the electric field. In the sheath 55, since a potential difference occurs along the direction perpendicular to the surface of the wafer W, active species 53, for example, cations, in the oxygen plasma passing through the sheath 55 are transferred by the sheath 55. Accelerated in a direction perpendicular to the surface of (W). As a result, the active species 53 in the oxygen plasma is in vertical contact with the silicon nitride film 52 formed on the surface of the wafer W (Fig. 3 (B)). The active species 53 in the oxygen plasma in contact with the silicon nitride film 52 changes the silicon nitride film 52 into the silicon monoxide film 54 as described above (Fig. 3 (C)).

Next, the wafer W is carried out from the chamber of the first process module 25 and carried into the chamber 38 of the second process module 34 via the loader module 13. At this time, the wafer W is placed on the mounting table 39.

Next, the pressure in the chamber 38 is set to 1.3 × 10 ¹ to 1.1 × 10 ³ Pa (1 to 8 Torr) by the APC valve 42 or the like, and the ambient temperature in the chamber 38 is set to 40 by the heater in the side wall. To 60 ° C. Then, HF gas is supplied from the gas supply part 43 of the shower head 40 toward the wafer W at a flow rate of 40 to 60 SCCM (HF gas supply step) (FIG. 3D). On the other hand, at this time, almost no water molecules are removed in the chamber 38, and no H ₂ O gas is supplied into the chamber 38.

As described above, the silicon monoxide film 54 contains water molecules to some extent, and HF gas reaching the silicon monoxide film 54 is combined with water molecules contained in the silicon monoxide film 54 to form hydrofluoric acid. . This hydrofluoric acid removes the silicon monoxide film 54. On the other hand, after the silicon monoxide film 54 is removed by the hydrofluoric acid and the thermal oxide film 51 is exposed, even though the HF gas reaches the thermal oxide film 51, the thermal oxide film 51 contains almost no water molecules. Therefore, HF gas hardly becomes hydrofluoric acid, so that the thermal oxide film 51 is hardly removed. As a result, the silicon monoxide film 54 is selectively etched and removed (FIG. 3E).

Next, the wafer W is carried out from the chamber 38 of the second process module 34 to complete the present process.

According to the substrate processing method according to the present embodiment, the active species 53 in the oxygen plasma is brought into contact with the wafer W having the thermal oxide film 51 and the silicon nitride film 52, and the wafer W is brought into contact with the wafer W. HF gas is supplied. The active species 53 in the oxygen plasma converts the silicon nitride film 52 into the silicon monoxide film 54 so that the hydrofluoric acid generated from the HF gas selectively changes the silicon monoxide film 54 changed from the silicon nitride film 52. Etch. Therefore, the silicon nitride film 52 can be selectively removed.

In the substrate processing method described above, when HF gas is supplied toward the wafer W, almost no water molecules are removed in the chamber 38, and since H ₂ O gas is not supplied into the chamber 38, water is supplied. In the thermal oxide film 51 containing almost no molecules, since the HF gas and the water molecules hardly bond and hydrofluoric acid hardly occurs, the oxide film 51 is hardly removed. Therefore, the silicon monoxide film 54 can be selectively etched more reliably.

In the substrate processing method described above, water molecules are almost removed in the chamber 38, and H ₂ O gas is not supplied into the chamber 38, and the silicon monoxide film 54 in the wafer W is used. The water molecules contained in are consumed by the reaction of SiO ₂ with hydrofluoric acid. Thus, the chamber 38 can be kept very dry. As a result, generation of particles and watermarks on the wafer W due to water molecules can be suppressed, whereby the reliability of the semiconductor device manufactured from the wafer W can be further improved.

Next, the substrate processing method which concerns on 2nd Embodiment of this invention is demonstrated.

This embodiment is basically the same as that of the above-described first embodiment, and the configuration of the substrate on which the treatment is performed is different from that of the above-described first embodiment. Therefore, description of the same structure is abbreviate | omitted and only the structure and effect | action different from 1st Embodiment are demonstrated below.

4 is a process chart showing the substrate processing method according to the present embodiment.

First, a thermally oxidized film 61 made of SiO ₂ is uniformly formed on the silicon substrate 60, and in the thermally oxidized film 61, a substantially rectangular polysilicon having a cross section which projects vertically from the surface of the wafer W '. A wafer W 'formed of a gate electrode 62 made of a convex conductive portion and a silicon nitride film 63 made of SiN is formed on the thermal oxide film 61. In this wafer W ', the silicon nitride film 63 covers not only the thermal oxide film 61 but also the side and top surfaces of the gate electrode 62 (Fig. 4 (A)). The wafer W 'is loaded into the chamber of the first process module 25 and placed on the ESC 28.

Next, oxygen gas is introduced into the chamber, and an electric field is generated between the upper electrode and the lower electrode to make oxygen gas into plasma to generate active species 53 in the oxygen plasma, and to activate the active species 53 in the oxygen plasma. The silicon nitride film 63 is brought into contact (oxygen plasma contact step). At this time, similarly to the first embodiment, the sheath 55 is generated in parallel to the surface of the wafer W 'in a space near the surface of the wafer W'.

Active species 53, such as cations, in the oxygen plasma passing through the sheath 55 are accelerated in the vertical direction with respect to the surface of the wafer W 'by the sheath 55 and move along the vertical direction. Since the direction perpendicular to the surface of the wafer W 'is parallel to the side of the gate electrode 62, the active species 53 in the oxygen plasma passing through the sheath 55 is approximately parallel to the side of the gate electrode 62. And vertically contact with the silicon nitride film 63 (FIG. 4B).

The active species 53 in the oxygen plasma in contact with the silicon nitride film 63 changes the silicon nitride film 63 to the silicon monoxide film 64 as described above, but in the silicon nitride film 63 Since the thickness along the moving direction (vertical direction to the surface of the wafer W ') of the active species 53 in the portion covering the side of the gate electrode 62 is thick, the active species 53 in the oxygen plasma has a gate It cannot fully enter into the part which covers the side surface of the electrode 62. As a result, the nitride part 63a which does not change to the silicon monoxide film 64 on the side of the gate electrode 62 remains (FIG. 4C). Meanwhile, the flat portion of the silicon nitride film 63 covering the top surface of the gate electrode 62 and the flat portion not covering the gate electrode 62 are changed into the silicon monoxide film 64 by the active species 53 in the oxygen plasma. (Selective oxidation step).

Next, the wafer W 'is taken out of the chamber of the first process module 25 and loaded into the chamber 38 of the second process module 34 via the loader module 13. At this time, the wafer W 'is placed on the mounting table 39.

Next, various conditions in the chamber 38 are set similarly to the various conditions of 1st Embodiment. Then, HF gas is supplied from the gas supply part 43 of the shower head 40 toward the wafer W 'at a flow rate of 40 to 60 SCCM (HF gas supply step) (Fig. 4 (D)). On the other hand, at this time, the chamber 38 is substantially remove the water molecules from within, and also does not supply the H ₂ O gas in the chamber 38, the same is true in the first embodiment.

Here, the HF gas reaching the silicon monoxide film 64 combines with the water molecules contained in the silicon monoxide film 64 to form hydrofluoric acid. This hydrofluoric acid removes the silicon monoxide film 64. On the other hand, after the silicon monoxide film 64 is removed by the hydrofluoric acid and the thermal oxide film 61 is exposed, even if the HF gas reaches the thermal oxide film 61, the thermal oxide film 61 contains almost no water molecules. Therefore, HF gas hardly becomes hydrofluoric acid, and the thermal oxide film 61 is hardly removed. In addition, even if the nitride portion 63a is exposed, the nitride portion 63a is made of SiN, and since the SiN hardly reacts with hydrofluoric acid, the nitride portion 63a is hardly removed. As a result, the silicon monoxide film 64 is selectively etched and removed, and a nitride portion 63a is formed on the side surface of the gate electrode 62 (FIG. 4E). The nitride portion 63a functions as a spacer separating the gate electrode 62 and the source / drain in a light doped drain (LDD) structure.

Next, the wafer W 'is taken out of the chamber 38 of the second process module 34 to complete the present process.

According to the substrate processing method according to the present embodiment, the active species 53 in the oxygen plasma is substantially parallel to the side surface (wafer W ') toward the silicon nitride film 63 covering the side surface and the top surface of the gate electrode 62. And the active species 53 in the oxygen plasma are in contact with the silicon nitride film 63. Since the thickness along the moving direction (vertical direction to the surface of the wafer W ') of the active species 53 in the portion covering the side surface of the gate electrode 62 in the silicon nitride film 63 is thick, the oxygen plasma The active species 53 cannot sufficiently enter the portion covering the side surface of the gate electrode 62. As a result, the flat portion of the silicon nitride film 63 covering the top surface of the gate electrode 62 and the flat portion not covering the gate electrode 62 are transferred to the silicon monoxide film 64 by the active species 53 in the oxygen plasma. The nitride portion 63a that is changed but does not change to the silicon monoxide film 64 on the side of the gate electrode 62 remains. The hydrofluoric acid generated from the HF gas selectively etches the silicon monoxide film 64 changed from the silicon nitride film 63, but hardly etches the nitride portion 63a. Accordingly, the silicon nitride film 63 does not remove the nitride portion 63a covering the side surface of the gate electrode 62, but is a flat portion and the gate electrode covering the top surface of the gate electrode 62, in particular. The silicon nitride film 63 of the flat portion not covering 62 can be selectively removed.

On the other hand, in the above-described substrate processing method, since it is difficult to completely remove all the silicon monoxide by hydrofluoric acid, it goes without saying that some silicon monoxide is contained in the nitriding portion 63a and the like.

In each of the embodiments described above, the silicon nitride film is oxidized using an oxygen plasma, but the silicon nitride film is not limited to this and can be used as long as it contains at least oxygen.

In each of the above-described embodiments, when the oxygen plasma is brought into contact with the silicon nitride film 52 (silicon nitride film 53) of the wafer W, a bias is applied to the lower electrode in the first process module 25. Although no voltage is applied, a bias voltage may be applied to the lower electrode in order to reliably contact the oxygen plasma with the silicon nitride film 52.

In addition, the board | substrate to which the substrate processing method which concerns on each embodiment is applied is not limited to the wafer for semiconductor devices, It may be various board | substrates used for LCD, a flat panel display (FPD), etc., a photomask, a CD board, a printed board, etc. .

An object of the present invention is to supply a storage medium storing program codes of software for realizing the functions of the above-described embodiments to a system or an apparatus so that the computer (or CPU or MPU, etc.) of the system or apparatus is stored. This is also achieved by reading and executing the program code stored in the program.

In this case, the program code itself read out from the storage medium realizes the functions of the above-described embodiments, and the program code and the storage medium storing the program code constitute the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, a hard disk, a magneto-optical disk, a CD-ROM, a CD-R, a CD-RW, a DVD-ROM, a DVD-RAM, a DVD- Optical disks such as RW and DVD + RW, magnetic tapes, nonvolatile memory cards, ROMs, and the like can be used. Alternatively, program code may be downloaded over a network.

In addition, by executing the program code read out by the computer, not only the functions of the above-described embodiments are realized, but also an OS (operating system) or the like running on the computer is part of the actual processing based on the instruction of the program code. It also includes a case where all of the above is performed and the functions of the above-described embodiments are realized by the processing.

Furthermore, after the program code read out from the storage medium is written into a memory included in the function expansion board inserted into the computer or the function expansion unit connected to the computer, the expansion function is expanded based on the instruction of the program code. A CPU or the like provided to the board or the expansion unit performs part or all of the actual processing, and the processing includes the case where the functions of the above-described embodiments are realized.

According to the substrate processing method of claim 1 and the substrate processing apparatus of claim 3, plasma containing oxygen is brought into contact with a substrate having a thermal oxide film and a nitride film formed by thermal oxidation treatment, and HF gas is supplied toward the substrate. do. The plasma containing oxygen changes the nitride film into an oxide film, and the hydrofluoric acid generated from the HF gas selectively etches the oxide film changed from the nitride film. Therefore, the nitride film can be selectively removed.

According to the substrate processing method of claim 2, active species in the plasma containing oxygen move substantially in parallel with the side surfaces toward the nitride films covering the side surfaces and the top surfaces of the conductive portions, and the active species are brought into contact with the nitride films to change the nitride films into oxide films. . Since the thickness along the direction of movement of the active species in the portion covering the side of the conductive portion in the nitride film is large, the active species cannot sufficiently enter the portion covering the side of the conductive portion. As a result, a nitride film that does not change in the oxide film on the side of the conductive portion remains. The hydrofluoric acid generated from the HF gas selectively etches the oxide film changed from the nitride film, but does not etch the nitride film. Therefore, other portions of the nitride film can be selectively removed without removing the portions covering the side surfaces of the conductive portions.

According to the substrate processing method of claim 3, the active species contains at least a cation. When the plasma is generated, the sheath generated in the space near the surface of the substrate accelerates cations toward the surface of the substrate. Therefore, the cation can be reliably brought into contact with the nitride film on the substrate.

According to the substrate processing method of claim 4, the flat portion of the nitride film is selectively oxidized. The hydrofluoric acid generated from the HF gas selectively etches the oxide film changed from the nitride film. Therefore, the flat portion of the nitride film can be selectively removed.

According to the substrate processing method of claim 5, active species in the plasma containing oxygen move substantially perpendicularly to the surface of the substrate toward the nitride film covering the side surface and the top surface of the convex conductive portion projecting vertically from the surface of the substrate, The active species is brought into contact with the nitride film to change the nitride film into an oxide film. Since the thickness along the vertical direction to the surface of the substrate of the portion covering the side of the conductive portion in the nitride film is thick, active species moving approximately perpendicular to the surface of the substrate can sufficiently enter the portion covering the side of the conductive portion. none. As a result, a nitride film that does not change into an oxide film on the side of the conductive portion remains. The hydrofluoric acid generated from the HF gas selectively etches the oxide film changed from the nitride film, but does not etch the nitride film. Therefore, other portions of the nitride film can be selectively removed without removing the portions covering the side surfaces of the conductive portions.

According to the substrate processing method of claim 6, the flat portion of the nitride film is selectively oxidized. The hydrofluoric acid generated from the HF gas selectively etches the oxide film changed from the nitride film. Therefore, the flat portion of the nitride film can be selectively removed.

Claims (7)

A substrate treating method for treating a substrate having a thermal oxide film and a nitride film formed by thermal oxidation treatment, An oxygen plasma contacting step of bringing the plasma containing oxygen into contact with the substrate, and And a HF gas supply step of supplying an HF gas toward the substrate in contact with the plasma containing oxygen. The method of claim 1, The substrate has a convex conductive portion protruding from the thermal oxide film, the nitride film covers the side and top surface of the conductive portion, In the oxygen plasma contacting step, the active species in the plasma containing oxygen moves in parallel with the side surface to contact the nitride film, thereby selectively oxidizing the flat portion of the nitride film. The method of claim 2, Wherein said active species comprises at least a cation. delete The method of claim 1, The substrate has a convex conductive portion projecting vertically from the surface of the substrate on the thermal oxide film, the nitride film covers the side and top surface of the conductive portion, In the oxygen plasma contacting step, the active species in the plasma containing oxygen is moved substantially perpendicular to the surface of the substrate to contact the nitride film to selectively oxidize the flat portion of the nitride film. delete A substrate processing apparatus for processing a substrate having a thermal oxide film and a nitride film formed by thermal oxidation treatment, An oxygen plasma contact device for bringing the plasma containing oxygen into contact with the substrate, and And an HF gas supply device for supplying HF gas toward the substrate in contact with the plasma containing oxygen.

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