TWI497597B - Substrate handling method - Google Patents

Description

Substrate processing method

The present invention relates to a substrate processing method, and more particularly to a substrate processing method for performing a process of forming a substrate on which a thermal oxide film and a tantalum nitride film are formed.

There are: a thermal oxide film formed by thermal oxidation treatment, for example, a hafnium oxide film; and a tantalum nitride film formed by a CVD process or the like; and a wafer (substrate) for a semiconductor device is well known. The tantalum nitride film is used as a spacer for separating the reflection preventing (BARC) film or the gate and the source/drain. Further, a thermal oxide film is used to constitute a gate oxide film.

The etching method of the tantalum nitride film is performed by slurrying a compound gas containing fluorine as a constituent element and not carbon as a constituent element, for example, performing plasmalization of a compound gas containing HF gas to cause the plasma formation. A method in which a compound gas reacts with carbon to form a chemical species (free radical), and a ruthenium nitride film is chemically etched is known (for example, refer to Patent Document 1).

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

However, the above chemical species are also etched together with the thermal oxide film. For example, a tantalum oxide film (thermal oxide film) is formed on the tantalum substrate as a gate insulating film, and a wafer of tantalum nitride film as an antireflection film is formed on the tantalum oxide film. At the time of the etching method described above, not only the tantalum nitride film but also the tantalum oxide film is etched together. Therefore, generally, since the gate insulating film is formed in a manner thinner than the anti-reflection film, the yttrium oxide film is removed first before the tantalum nitride film is removed, and as a result, the tantalum substrate is damaged (etched).

SUMMARY OF THE INVENTION An object of the present invention is to provide a substrate processing method which can selectively remove a nitride film.

In order to achieve the above object, a 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, and is characterized in that And an oxygen plasma contacting step of contacting the oxygen-containing plasma with the substrate; and an HF gas supply step for supplying the HF gas to the substrate contacting the oxygen-containing plasma, when the HF gas is supplied The water molecule in the chamber is removed, and the nitride film is a tantalum nitride film. In the oxygen plasma contact step, the tantalum oxide film is changed, and the thermal oxide film and the first germanium oxide film are simultaneously present. The HF gas, the thermal oxide film and the niobium monoxide film have different densities, and after removing water molecules from the chamber, the HF gas is supplied to make the yttrium oxide film having a low density among the two types of yttrium oxide films. Water molecules are left on the surface, and the ruthenium oxide film having a low density as described above is selectively removed.

The substrate processing method according to the first aspect of the invention, wherein the substrate includes a convex conductive portion protruding on the thermal oxide film, and the nitride film Covering the side surface and the top surface of the conductive portion, in the oxygen plasma contacting step, the active species in the oxygen-containing plasma moves substantially in parallel with the side surface to contact the nitride film.

The substrate processing method according to the invention of claim 2, wherein the active species contains at least a cation.

The substrate processing method described in item 4 of the patent application is as follows The substrate processing method according to Item 2 or 3, wherein the substrate has a selective oxidation step of selectively oxidizing a flat portion of the nitride film.

The substrate processing method according to claim 1, wherein the substrate has a convex conductive material that protrudes perpendicularly from the surface of the substrate on the thermal oxide film. The nitride film covers a side surface and a top surface of the conductive portion, and in the oxygen plasma contacting step, the active species in the oxygen-containing plasma moves slightly perpendicular to the surface of the substrate to contact the nitriding membrane.

The substrate processing method according to claim 5, wherein the substrate processing method according to claim 5, further comprising a selective oxidation step of selectively oxidizing the flat portion of the nitride film.

The substrate processing method according to claim 1, wherein the HF gas supply step removes water molecules from the chamber during the HF gas supply step. The pressure is set at 1.3 × 10 ² to 1.1 × 10 ³ Pa (1 to 8 Torr), and the ambient temperature in the chamber is set at 40 ° C to 60 ° C.

The substrate processing method according to the first aspect of the invention is the substrate processing method according to the first aspect of the invention, wherein the HF gas system is supplied at a flow rate of 40 SCCM to 60 SCCM.

According to the substrate processing method of the first aspect of the invention, the 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 to the substrate. The plasma containing oxygen changes the nitride film into an oxide film, and the fluoric acid generated by the HF gas selectively etches the oxide film formed by the change of the nitride film. Therefore, the nitride film can be selectively removed.

According to the substrate processing method of the second aspect of the invention, the active species in the oxygen-containing plasma is moved in parallel with the side surface so as to face the nitride film covering the side surface and the top surface of the conductive portion, and the activity is made. The nitride film is contacted to change the nitride film into an oxide film. Since the portion covering the side surface of the conductive portion of the nitride film has a large thickness along the moving direction of the active species, the active species cannot sufficiently enter the portion covering the side surface of the conductive portion. As a result, a nitride film which is not changed into an oxide film remains on the side surface of the conductive portion. The fluoric acid generated by the HF gas selectively etches the oxide film which is changed by the nitride film, however, the nitride film is not etched. Therefore, in the nitride film, the portion covering the side surface of the conductive portion is not removed, so that other portions can be selectively removed.

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

According to the substrate processing method of the fourth aspect of the invention, the flat portion of the nitride film can be selectively oxidized. The fluoric acid generated by the HF gas selectively etches the oxide film which is changed by the nitride film. Therefore, the flat portion of the nitride film can be selectively removed.

The substrate processing method according to claim 5, wherein the active species in the oxygen-containing plasma are directed toward the nitride film covering the side surface and the top surface of the convex conductive portion that protrudes perpendicularly from the surface of the substrate. The active species can contact the nitride film to change the nitride film into an oxide film by moving substantially perpendicularly to the surface of the substrate. Since the thickness of the surface of the substrate along the portion of the nitride film covering the side surface of the conductive portion is large, the active species that move substantially vertically with respect to the surface of the substrate cannot sufficiently cover the side portion of the conductive portion. Share. As a result, a nitride film which does not change into an oxide film remains on the side surface of the conductive portion. The fluoric acid generated by the HF gas selectively etches the oxide film which is changed by the nitride film, however, the nitride film is not etched. Therefore, in the nitride film, the portion covering the side surface of the conductive portion is not removed, so that other portions can be selectively removed.

According to the substrate processing method of the sixth aspect of the invention, the flat portion of the nitride film can be selectively oxidized. The fluoric acid generated by the HF gas selectively etches the oxide film which is changed by the nitride film. Therefore, the flat portion of the nitride film can be selectively removed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, a first embodiment of the present invention will be described with respect to a substrate processing system for performing a substrate processing method.

Fig. 1 is a plan view showing a schematic configuration of a substrate processing system for carrying out the substrate processing method of the present embodiment.

In the first embodiment, the substrate processing system 10 (substrate processing apparatus) includes a first processing boat 11 for performing plasma processing on a wafer (hereinafter simply referred to as "wafer") W (substrate) for a semiconductor device. The second processing boat 12 that performs the selective etching process described later on the wafer W that has been subjected to the plasma treatment in the first processing boat 11 is disposed in parallel with the first processing boat 11 and is connected to the first processing boat 11 The rectangular shape of the second processing boat 12 is used as a loading module 13 for use in a shared transfer room.

In addition to the first processing boat 11 and the second processing boat 12 described above, the loading module 13 is connected to a front opening cassette (Front Opening Unified Pod) 14 in which containers for accommodating 25 wafers W are respectively placed. The three front open cassette mounting platforms 15, the guides 16 for pre-aligning the positions of the wafers W carried out from the front open wafer cassette 14, and the first and the third for measuring the surface state of the wafer W 2 IMS (Integrated Metrology System, Therma-Wave, Inc.) 17, 18.

The first processing boat 11 and the second processing boat 12 are coupled to the side wall in the longitudinal direction of the loading module 13 and are disposed to face the three front opening wafer cassette mounting tables 15 with the loading module 13 interposed therebetween. The first IMS 17 is disposed at one end of the length of the loading module 13 , and the second IMS 18 is disposed at the other end of the loading module 13 . The second IMS 18 is connected to the three front open cassette mounting platforms 15 . Configured for side by side.

The loading module 13 has a step-type arm type arm mechanism 19 for transporting the wafer W therein, and a wafer W disposed on the side wall corresponding to each of the front opening type wafer cassette mounting tables 15 The three loading ports 20 used for the input port. The transport arm mechanism 19 takes out the wafer W from the open wafer cassette 14 before being placed on the front open wafer cassette mounting table 15 via the load port 20, and the wafer W to be taken out is directed to the first processing boat 11 and the second The processing boat 12, the guide 16, the first IMS 17, or the second IMS 18 are carried out and carried in.

The monitor of the first IMS 17-series optical system has a table 21 for placing the loaded wafer W and an optical sensor 22 directed to the wafer W placed on the table 21 for The surface shape of the wafer W is measured, for example, a CD (Critical Dimension) value of a film thickness of a polysilicon film, a wiring trench, and a gate. The second IMS 18 is also an optical system monitor, and has a table 23 and an optical sensor 24 similarly to the first IMS 17.

The first processing boat 11 includes a first processing module 25 (oxygen plasma contact device) that performs plasma processing on the wafer W, and a built-in type in which the wafer W is taken up to the first processing module 25 The first load locker 27 of the first transport arm 26 of the single-turn type is placed.

The first processing 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 set to The wafer W can be subjected to a moderate interval of plasma processing. Further, the top of the lower electrode has an ESC 28 that holds the wafer W by Coulomb force or the like.

The first processing module 25 introduces oxygen into the chamber, and generates an electric field by the electric field generated between the upper electrode and the lower electrode to generate oxygen plasma, which is contained in the oxygen plasma. The active species is subjected to plasma treatment, specifically, plasma treatment is performed by contacting the cations with the cations.

The first processing boat 11 maintains the internal pressure of the loading module 13 at atmospheric pressure, and maintains the internal pressure of the first processing module 25 at a vacuum. Therefore, the first load lock module 27 has a vacuum gate valve 29 at the connection portion with the first process module 25 and an air gate valve 30 at the connection portion with the load module 13 to form an internal pressure adjustable vacuum. Prepare the transfer room.

The first transfer arm 26 is provided at a substantially central portion of the inside of the first placement lock module 27, and the first buffer portion is provided closer to the first processing module 25 side with respect to the first transfer arm 26 31. The second buffer portion 32 is provided on the side closer to the loading module 13 with respect to the first transfer arm 26. The first buffer portion 31 and the second buffer portion 32 are disposed on a rail for supporting the support portion (33) of the wafer W disposed at the end portion of the first transfer arm 26, and the plasma is applied. The processed wafer W is temporarily retracted above the track of the support portion 33, and the unprocessed wafer W and the processed wafer W can be smoothly carried in and out of the first processing module 25.

The second processing boat 12 has a second processing module 34 for performing a selective etching process to be described later on the wafer W, and is connected to the second processing module 34 via a vacuum gate valve 35, and receives the wafer W. The second placement lock module 37 of the second transfer arm 36 of the connected type is built into the second processing module 34.

2 is a cross-sectional view of the second processing module of FIG. 1, FIG. 2(A) is a cross-sectional view taken along line I-I of FIG. 1, and FIG. 2(B) is a second (A) drawing. A magnified view of Part A.

In the second (A) diagram, the second processing 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 mounting table 39. The shower head 40 disposed above the chamber 38 and the TMP (Turbo Molecular Pump) 41 for performing the exhaust of the gas or the like in the chamber 38; and disposed between the chamber 38 and the TMP 41 for controlling An APC (Adaptive Pressure Control) valve 42 of a variable pressure valve in the chamber 38.

The shower head 40 has a disk-shaped oxygen supply unit 43 (HF gas supply device), and the oxygen supply unit 43 has a buffer chamber 44. The buffer chamber 44 communicates into the chamber 38 via a gas vent 45.

The buffer chamber 44 of the oxygen supply unit 43 of the showerhead 40 is connected to an 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. A heater (not shown) is built in the oxygen supply unit 43 of the shower head 40, and for example, a heating element is built in. The heating element controls the temperature of the HF gas within the buffer chamber 44.

The shower head 40 has a shape in which the opening of the gas vent hole 45 into the chamber 38 is formed by the shape in which the end is enlarged, as shown in Fig. 2(B). Thereby, the HF gas can be efficiently diffused into the chamber 38. Further, since the gas vent hole 45 has a neck-shaped cross section, it is possible to prevent the residue or the like generated in the chamber 38 from flowing back to the gas vent hole 45 and the buffer chamber 44.

Further, in the second processing module 34, a heater (not shown) is built in the side wall of the chamber 38, and for example, a heating element is built in. Thereby, the ambient temperature in the chamber 38 can be set higher than the normal temperature, and the niobium oxide film 54 can be removed by the use of hydrofluoric acid, which will be described later. Further, by heating the side wall of the heating element in the side wall, it is possible to prevent the residue generated when the niobium oxide film 54 is removed by the hydrofluoric acid from adhering to the inner side of the side wall.

A refrigerant chamber (not shown) having a temperature adjustment mechanism inside the mounting table 39. The refrigerant is supplied to the refrigerant chamber at a predetermined temperature, for example, cooling water or a fluorine-based inactive chemical liquid is supplied, 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 second placement lock module 37 has a casing-shaped transfer chamber (chamber) 46 in which the second transfer arm 36 is built. Further, the internal pressure of the loading module 13 is maintained at atmospheric pressure, while the internal pressure of the second processing module 34 is maintained at or below atmospheric pressure, for example, maintained at a near vacuum. Therefore, the second mounting lock module 37 is provided with a vacuum gate valve 35 at the connection portion with the second processing module 34, and an atmospheric door valve 47 is provided at the connection portion with the loading module 13, so that the internal pressure can be adjusted. Vacuum preparation transfer room.

Further, the substrate processing system 10 includes an operation panel 48 disposed at one end of the loading unit 13 in the longitudinal direction. The operation panel 48 has a display unit composed of, for example, an LCD (Liquid Crystal Display), and the display unit displays the operation state of each component of the substrate processing system 10.

However, a method of selectively etching an oxide film containing impurities by using a thermal oxide film formed by thermal oxidation treatment and a wafer containing an oxide film formed by CVD treatment, for example, without using HF gas, A method of pulverizing a mixed gas of HF gas and H ₂ O gas is known (for example, refer to Japanese Laid-Open Patent Publication No. Hei 06-181188).

Further, the present inventors have found that in order to make the selection ratio of the oxide film containing impurities with respect to the thermal oxide film higher than the above method, various experiments are carried out, and in the environment where H ₂ O is scarcely present, H ₂ O gas is not supplied. When only the HF gas is supplied to the wafer W, the selection ratio of the oxide film containing impurities with respect to the thermal oxide film can be greatly improved.

Next, the inventors conducted a careful study on the mechanism for realizing the above-described high selection ratio, and inferred the hypothesis explained below.

The HF gas is combined with H ₂ O to form a hydrofluoric acid which invades and removes the oxide film. Therefore, in the environment where H ₂ O is scarcely present, in order to make the HF gas a hydrofluoric acid, it is necessary to bond with the water (H ₂ O) molecule contained in the oxide film.

Since the oxide film containing impurities is formed by vapor deposition such as CVD treatment, the structure of the film is loose and it is easy to adsorb water molecules. Therefore, the oxide film containing impurities contains a certain degree of water molecules. The HF gas reaching the oxide film containing impurities is combined with the water molecule to become hydrofluoric acid. Next, the hydrofluoric acid invades an oxide film containing impurities.

On the other hand, since the thermal oxide film is formed by thermal oxidation treatment in an environment of 800 to 900 ° C, the film is formed without water molecules, and further, since the structure of the film is dense, it is not easy to adsorb water molecules. Therefore, the thermal oxide film hardly contains water molecules. The supplied HF gas reaches the thermal oxide film even because water molecules do not exist and do not become hydrofluoric acid. As a result, the thermal oxide film is not invaded.

Thereby, in the environment where H ₂ O is scarcely present, when the H ₂ O gas is not supplied and only the HF gas is supplied to the wafer W, the selection ratio of the oxide film containing impurities with respect to the thermal oxide film can be greatly improved (selection Sex etching treatment).

In the present embodiment, the tantalum substrate 50 shown in Fig. 3(A) is formed by laminating a thermal oxide film 51 composed of SiO ₂ formed by thermal oxidation treatment and SiN formed by CVD treatment. The wafer W of the tantalum nitride film 52 (nitride film) is subjected to the above-described selective etching treatment using hydrofluoric acid in order to selectively remove the tantalum nitride film 52. Specifically, after the tantalum nitride film 52 of the wafer W is changed into an oxide film by an oxidation treatment, the above selective etching treatment using hydrofluoric acid is performed.

Hereinafter, the oxidation treatment of the tantalum nitride film 52 of the present embodiment will be described.

The active species 53 in the oxygen plasma (O ₂ plasma) produced by the oxygen (O ₂ ) gas in the tantalum nitride film 52, for example, is contacted with a cation (Fig. 3(B)) to form a tantalum nitride film. The active species in SiN and oxygen plasma in 52 produces a chemical reaction of the formula: 2SiN+O ₂ → 2SiNO to produce SiNO generate. Since SiNO is an unstable substance, nitrogen is separated and sublimated as shown in the following formula, and 2SiNO → 2SiO + N ₂ ↑ produces SiO (antimony oxide). Thereby, the tantalum nitride film 52 is changed to a ruthenium oxide film 54 composed of SiO (Fig. 3(C)). Since the niobium monoxide film 54 is changed by the loosening of the tantalum nitride film 52 formed by the CVD treatment, the film structure of the niobium monoxide film 54 is also loose. Therefore, the niobium monoxide film 54 contains some degree of water molecules. In the present embodiment, the niobium monoxide film 54 is selectively etched by a selective etching treatment using hydrofluoric acid, and as a result, the tantalum nitride film 52 can be selectively removed.

Next, the substrate processing method of the present embodiment will be described. The substrate processing method of this embodiment is implemented by the substrate processing system 10 of Fig. 1 .

First, a wafer W on which a thermal oxide film 51 made of SiO ₂ is formed on a tantalum substrate 50 and a tantalum nitride film 52 made of SiN is formed on the thermal oxide film 51 (Fig. 3(A)) . Next, the wafer W is carried into the chamber of the first processing module 25 and placed on the ESC 28.

Next, oxygen is introduced into the chamber, and an electric field is generated between the upper electrode and the lower electrode to perform plasma electrolysis of the oxygen to generate an active species 53 in the oxygen plasma, and the active species 53 in the oxygen plasma is contact nitrided. Decor film 52 (oxygen plasma contact step). At this time, the skin sheath 55 parallel to the surface of the wafer W is generated in the space near the surface of the wafer W due to the electric field. Since the skin sheath 55 generates a potential difference along the vertical direction with respect to the surface of the wafer W, the active species 53 in the oxygen plasma passing through the sheath sheath 55, for example, the cations may face the wafer W due to the sheath 55. Accelerate in the vertical direction. As a result, the active species 53 in the oxygen plasma vertically contacts the tantalum nitride film 52 formed on the surface of the wafer W (Fig. 3(B)). The active species 53 in the oxygen plasma contacting the tantalum nitride film 52, as described above, changes the tantalum nitride film 52 to a tantalum oxide film 54 (Fig. 3(C)).

Next, the wafer W is carried out of the chamber of the first processing module 25, and is carried into the chamber 38 of the second processing module 34 via the loading 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 ² 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. 60 ° C. Next, HF gas is supplied to the wafer W from the oxygen supply unit 43 of the showerhead 40 at a flow rate of 40 to 60 SCCM (HF gas supply step) (Fig. 3(D)). Further, at this time, almost all of the water molecules in the chamber 38 are removed, and further, the H ₂ O gas is not supplied into the chamber 38.

The niobium monoxide film 54 contains a certain amount of water molecules as described above, and the HF gas reaching the niobium monoxide film 54 is combined with the water molecules contained in the niobium oxide film 54 to become hydrofluoric acid. Next, the fluoric acid removes the hafnium oxide film 54. On the other hand, after removing the niobium monoxide film 54 by hydrofluoric acid to expose the thermal oxide film 51, even if the HF gas reaches the thermal oxide film 51, since the thermal oxide film 51 contains almost no water molecules, almost no HF gas becomes hydrofluoric acid. Almost no thermal oxide film 51 is removed. As a result, the hafnium oxide film 54 can be selectively removed by etching (Fig. 3(E)).

Next, the wafer W is carried out of the chamber 38 of the second processing module 34, and the process is terminated.

According to the substrate processing method of 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 tantalum nitride film 52, and the HF gas is supplied to the wafer W. The active species 53 in the oxygen plasma changes the tantalum nitride film 52 to a tantalum oxide film 54, and the fluorine acid generated by the HF gas selectively etches the tantalum nitride film 52 to become one of the tantalum oxide films 54. Therefore, the tantalum nitride film 52 can be selectively removed.

In the above substrate processing method, when the HF gas is supplied to the wafer W, the water molecules in the chamber 38 are almost completely removed, and further, since the H ₂ O gas is not supplied into the chamber 38, the thermal oxidation of the water molecules is hardly contained. In the film 51, since the combination of the HF gas and the water molecules hardly occurs and the hydrofluoric acid hardly occurs, the oxide film 51 is hardly removed. Therefore, the hafnium oxide film 54 can be selectively etched more selectively.

Further, in the above substrate processing method, the water molecules in the chamber 38 are almost completely removed, and the H ₂ O gas is not supplied into the chamber 38. Further, the water molecules contained in the ruthenium film 54 of the wafer W are contained. It is applied to the reaction of SiO ₂ and hydrofluoric acid and is consumed. Therefore, the inside of the chamber 38 can be maintained in an extremely dry state. As a result, generation of water particles by the water molecules and watermarks on the wafer W can be suppressed, so that the reliability of the semiconductor device manufactured by the wafer W can be improved.

Next, a substrate processing method according to a second embodiment of the present invention will be described.

The configuration and operation of the present embodiment are basically the same as those of the above-described first embodiment, and only the configuration of the processed substrate is different from that of the first embodiment. Therefore, the description of the same configuration will be omitted, and only the configuration and operation different from the first embodiment will be described below.

Fig. 4 is a process chart of the substrate processing method of the embodiment.

First, a thermal oxide film 61 made of SiO ₂ is uniformly formed on the tantalum substrate 60, and the thermal oxide film 61 is formed of a polycrystalline crucible having a substantially rectangular cross section which protrudes perpendicularly from the surface of the wafer W'. A gate 62 (a convex conductive portion) is formed, and a wafer W' of a tantalum nitride film 63 made of SiN is formed on the thermal oxide film 61. In the wafer W', not only the thermal oxide film 61 is the tantalum nitride film 63, but also the tantalum nitride film 63 covers the side surface and the top surface of the gate 62 (Fig. 4(A)). Next, the wafer W' is carried into the chamber of the first processing module 25 and placed on the ESC 28.

Next, oxygen is introduced into the chamber, and an active species 53 is generated in the oxygen plasma by the electric field generated by the electric field between the upper electrode and the lower electrode, so that the active species 53 in the oxygen plasma contacts the tantalum nitride film. 63 (oxygen plasma contact step). At this time, as in the first embodiment, a sheath 55 parallel to the surface of the wafer W' occurs in a space near the surface of the wafer W'.

The active species 53 in the oxygen plasma of the sheath sheath 55, for example, cations, are accelerated in the vertical direction relative to the surface of the wafer W' by the sheath sheath 55 and move in the vertical direction. Since the vertical direction with respect to the surface of the wafer W' is parallel to the side surface of the gate 62, the movement of the active species 53 in the oxygen plasma through the sheath 85 is substantially parallel to the side of the gate 62, and the vertical contact with the tantalum nitride film 63 (Fig. 4(B)).

The active species 53 in the oxygen plasma contacting the tantalum nitride film 63, as described above, changes the tantalum nitride film 63 to a tantalum oxide film 64, however, because along the gate 62 covering the tantalum nitride film 63 The thickness of the active species 53 on the side is relatively large (relative to the vertical direction of the surface of the wafer W'), and the active species 53 in the oxygen plasma cannot sufficiently enter the portion of the side covering the gate 62. . As a result, a nitride portion 63a which is not changed to the hafnium oxide film 64 remains on the side surface of the gate 62 (Fig. 4(C)). On the other hand, the flat portion of the tantalum nitride film 63 covering the top surface of the gate electrode 62 and the flat portion of the uncovered gate 62 are changed into a hafnium oxide film 64 due to the active species 53 in the oxygen plasma. (Selective oxidation step).

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

Next, the conditions in the chamber 38 are set to be the same as those in the first embodiment. Next, HF gas (HF gas supply step) is supplied from the oxygen supply unit 43 of the showerhead 40 to the wafer W' at a flow rate of 40 to 60 SCCM (Fig. 4(D)). Further, at this time, the water molecules in the chamber 38 are almost completely removed and the H ₂ O gas is not supplied into the chamber 38, which is the same as in the first embodiment.

Therefore, the HF gas reaching the niobium monoxide film 64 is combined with the water molecules contained in the niobium oxide film 64 to become hydrofluoric acid. Next, the fluoric acid removes the ruthenium oxide film 64. On the other hand, after removing the niobium monoxide film 64 by hydrofluoric acid to expose the thermal oxide film 61, even if the HF gas reaches the thermal oxide film 61, since the thermal oxide film 61 contains almost no water molecules, the HF gas hardly becomes a hydrofluoric acid. And almost no thermal oxide film 61 is removed. Further, even if the nitride portion 63a is exposed, since the nitride portion 63a is made of SiN, almost no SiN reacts with the hydrofluoric acid, so that the nitride portion 63a is hardly removed. As a result, the hafnium oxide film 64 is selectively removed and the nitride portion 63a is formed on the side surface of the gate 62 (Fig. 4(E)). The nitriding portion 63a functions as a spacer for separating the gate 62 and the source/drain in the LDD (Light Doped Drain) structure.

Next, the wafer W' is carried out from the chamber 38 of the second processing module 34, and the processing is terminated.

According to the substrate processing method of the present embodiment, the active species 53 in the oxygen plasma is directed toward the tantalum nitride film 63 covering the side surface and the top surface of the gate 62 so as to be substantially parallel to the side surface (along the surface relative to the wafer W' In the vertical direction, the active species 53 in the oxygen plasma contacts the tantalum nitride film 63. The thickness of the active species 53 along the side of the tantalum nitride film 63 covering the side surface of the gate 62 (the vertical direction with respect to the surface of the wafer W') is large. The active species 53 in the oxygen plasma cannot sufficiently enter the portion covering the side of the gate 62. As a result, the flat portion of the top surface of the tantalum nitride film 63 covering the gate electrode 62 and the flat portion of the uncovered gate electrode 62 are changed into the hafnium oxide film 64 due to the active species 53 in the oxygen plasma. However, On the side of the gate 62, a nitride portion 63a which changes into a hafnium oxide film 64 remains. The fluoric acid generated by the HF gas selectively etches the tantalum nitride film 63 into one of the tantalum oxide films 64, however, the nitride portion 63a is hardly etched. Therefore, the nitride portion 63a of the tantalum nitride film 63 covering the side surface of the gate electrode 62 is not removed, and other portions can be selectively removed, specifically, the top surface of the gate electrode 62 is selectively removed. The portion and the tantalum nitride film 63 which does not cover the flat portion of the gate 62.

Further, in the above substrate processing method, since it is difficult to completely remove all of the cerium oxide by the hydrofluoric acid, the nitriding portion 63a or the like naturally contains a certain amount of cerium oxide.

In the above embodiments, the oxidation of the tantalum nitride film is performed by the oxygen plasma. However, the oxidation of the tantalum nitride film is not limited thereto, and may be any plasma containing at least oxygen.

Further, in each of the above embodiments, when the oxygen plasma is brought into contact with the tantalum nitride film 52 (tantalum nitride film 53) of the wafer W, a bias voltage is not applied to the lower electrode of the first processing module 25. However, In order to allow the oxygen plasma to reliably contact the tantalum nitride film 52, a bias voltage may be applied to the lower electrode.

Further, the substrate to which the substrate processing method of each embodiment is applied is not limited to a wafer for a semiconductor device, and may be various substrates, a photomask, a CD substrate, a printed substrate, or the like used for an LCD, an FPD (Flat Panel Display) or the like. .

For the purpose of the present invention, a computer or a computer (or CPU, MPU, etc.) of the system or device may be provided by a memory medium that memorizes the code of the software for realizing the functions of the above embodiments. Read and execute the code stored in the memory medium to achieve.

At this time, the code itself read from the memory medium realizes the functions of the above embodiments, and the present invention is constituted by the code and the memory medium in which the code is stored.

In addition, as a memory medium for providing code, for example, FLOPPY (registered trademark) disc, hard disc, optical disc, CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM can be used. , CD-RW, DVD+RW, etc., optical discs, non-volatile memory cards, ROM, etc. In addition, the code can also be downloaded via the Internet.

In addition, by executing the read code by the computer, not only can the functions of the above embodiments be implemented, but also an OS (operation system) operating on the computer can perform part of the actual processing according to the instruction of the code or All of these functions are also included when the functions of the above embodiments are implemented by this processing.

In addition, the code read from the memory medium is written into the memory of the function expansion unit of the computer or the function expansion unit connected to the computer, and the expansion board of the expansion function is provided according to the instruction of the code. The CPU or the like of the expansion unit performs some or all of the actual processing, and the functions of the above embodiments are also included in the processing.

10. . . Substrate processing system

11. . . First processing boat

12. . . Second processing boat

25. . . First processing module

34. . . Second processing module

38. . . Chamber

39. . . Mounting table

40. . . Shower head

43. . . Oxygen supply department

50, 60. . . Bismuth substrate

51, 61. . . Thermal oxide film

52, 63. . . Tantalum nitride film

53. . . Active species

54, 64. . . Niobium oxide film

62. . . Gate

Fig. 1 is a plan view showing a schematic configuration of a substrate processing system for performing a substrate processing method according to a first embodiment of the present invention.

2 is a cross-sectional view of the second processing module of FIG. 1, FIG. 2(A) is a cross-sectional view taken along line I-I of FIG. 1, and FIG. 2(B) is a second (A) drawing. A magnified view of Part A.

Fig. 3 is a process diagram of a substrate processing method according to a first embodiment of the present invention.

Fig. 4 is a process diagram of a substrate processing method according to a second embodiment of the present invention.

50. . . Bismuth substrate

51. . . Thermal oxide film

52. . . Tantalum nitride film

53. . . Active species

54. . . Niobium oxide film

Claims (8)

A substrate processing method for processing a substrate having a thermal oxide film and a nitride film formed by thermal oxidation treatment, the substrate processing method having an oxygen plasma contacting step for containing a plasma of oxygen is in contact with the substrate; and an HF gas supply step is for supplying HF gas to the substrate contacting the oxygen-containing plasma, and removing water molecules in the chamber when the HF gas is supplied, The nitride film is a tantalum nitride film, and is changed into a hafnium oxide film in the oxygen plasma contacting step, and the HF gas is supplied while the thermal oxide film and the niobium monoxide film are simultaneously present, and the thermal oxide film and The density of the niobium monoxide film is different from each other, and after the water molecules are removed from the chamber, the HF gas is supplied, so that water molecules remain on the low-density hafnium oxide film in the two types of the hafnium oxide film, and the selectivity is selective. The ruthenium oxide film having a low density as described above is removed. The substrate processing method according to claim 1, wherein the substrate includes a convex conductive portion protruding on the thermal oxide film, and the nitride film covers a side surface and a top surface of the conductive portion, and the oxygen plasma In the contacting step, the active species in the oxygen-containing plasma substantially moves in parallel with the side surface to contact the nitride film. The substrate processing method described in claim 2, Wherein the aforementioned active species contain at least a cation. The substrate processing method according to claim 2, wherein the selective oxidation step of selectively oxidizing the flat portion of the nitride film is provided. The substrate processing method according to claim 1, wherein the substrate has a convex conductive portion that protrudes perpendicularly from a surface of the substrate on the thermal oxide film, and the nitride film covers a side surface and a top portion of the conductive portion. In the oxygen plasma contacting step, the active species in the oxygen-containing plasma moves slightly perpendicular to the surface of the substrate to contact the nitride film. The substrate processing method according to claim 5, which has a selective oxidation step of selectively oxidizing a flat portion of the nitride film. The substrate processing method according to claim 1, wherein in the HF gas supply step, when water molecules are removed from the chamber, the chamber pressure is set to 1.3 × 10 ² to 1.1 × 10 ³ Pa (1~8 Torr) sets the ambient temperature in the chamber to 40 °C to 60 °C. The substrate processing method according to claim 1, wherein The HF gas system described above is supplied at a flow rate of 40 SCCM to 60 SCCM.