JP4564310B2 - Manufacturing method of semiconductor device - Google Patents

Description

  The present invention relates to a method for manufacturing a semiconductor device using a high dielectric film.

  An important element constituting a large scale integrated circuit (ULSI) is a MOSFET (hereinafter simply referred to as a transistor). In order to increase the degree of integration of ULSI, attempts have been made to reduce processing dimensions. Accordingly, it is necessary to increase the gate insulating film capacitance of the transistor, and thus it is necessary to reduce the film thickness. Conventionally, a silicon oxide film has been used as the gate insulating film. However, when this film thickness is reduced, a large amount of tunnel leakage current flows, causing a problem that the transistor does not operate. For this reason, there has been a demand to increase the insulation capacity without reducing the physical film thickness. In order to meet this demand, since the insulation capacity is expressed by ε / d (ε: dielectric constant, d: film thickness), a high dielectric (hereinafter referred to as High-k) film material having a high dielectric constant is used. Attempts have been made.

  Generally, a metal oxide is used as a high-k film material. However, when this film is formed on a silicon substrate which is a base material of ULSI, the interface causes various complicated reactions.

  For example, oxygen in the metal oxide may be taken away by Si, and the reduced metal and Si may cause an alloy reaction (silicidation) to destroy the insulating property of the insulating capacitance film. Even if the metal oxide film is not completely reduced, dangling bonds are likely to be formed at the interface between the metal oxide and Si, which forms a fixed charge and adversely affects the transistor characteristics. Therefore, it has been studied to use an extremely thin oxide film or the like inserted between the gate insulating film and the silicon substrate. Similarly, the same problem may occur between the gate insulating film and the upper electrode polysilicon. For this reason, a silicon nitride film may be inserted as an interface buffer layer between the gate insulating film and the polysilicon as the upper electrode. The silicon nitride film is inserted because it is confirmed that the silicon nitride film forms a stable interface with the metal oxide film without depriving oxygen. This is because the dielectric constant is higher than that of the silicon oxide film.

In addition, in a transistor using a high-k film material, boron may be diffused into the polysilicon after the polysilicon is formed in order to make the gate electrode p ⁺ type. In this case, boron easily diffuses in the high-k film and may reach the silicon substrate. This is called boron penetration. When this boron penetration occurs, boron atoms exist at the interface between the High-k film and the silicon substrate, which becomes an electron acceptor and causes an abnormality in the operation of the transistor. By inserting nitrogen into the high-k film, this boron penetration can be prevented. This is because nitrogen atoms serve as a barrier when boron atoms diffuse through the film. For this reason, an attempt has been made to put a large amount of nitrogen in the High-k film.

When a silicon nitride film is formed on a high-k film by CVD, it is usually formed using SiH ₄ and NH ₃ at a high temperature of 700 ° C. or higher. Therefore, the high-k film, which is a metal oxide film, is reduced. The problem is that oxygen is deprived by exposure to the atmosphere, that is, the insulation is deteriorated by reduction. For this reason, the silicon nitride film is often formed by low temperature CVD using HCD (Hexa-chloro-Disilane: Si ₂ Cl ₆ ) and ammonia (NH ₃ ). However, since the silicon nitride film formed at a low temperature has an unstable bonding state between Si and N, when formed on an oxide film such as a high-k film, silicon nitride is formed by surplus oxygen present in the high-k film. There is a problem that oxygen is taken in during the film formation, resulting in a mixed film of a silicon nitride film and a SiO ₂ film, and the dielectric constant is lowered.

In addition, when nitrogen is introduced into the high-k film, a method of introducing nitrogen by holding the high-k film in an ammonia atmosphere at a high temperature of 700 to 900 ° C. may be used. There was a problem that nitrogen reached near the substrate. In order to solve this problem, an attempt has been made to introduce nitrogen at a low temperature using direct plasma. In this case, it is ideal that a large amount of nitrogen is introduced into the surface of the High-k film, but it has been found that the nitrogen reaches the silicon substrate interface. This phenomenon will be described with reference to FIG. A High-k film 422 is formed on a SiO ₂ layer (hereinafter referred to as an interface SiO ₂ layer) 421 which is a base film on the silicon substrate 400 (FIG. 7A), and the High-k film 422 is directly applied to the plasma P When nitrogen is introduced into the substrate, a gentle gradient nitrogen profile is created from the High-k film 422 through the interface SiO ₂ layer 421 to the substrate surface (FIG. 7B).

In this case, it is known that the nitrogen forms a dangling bond at the silicon substrate interface, forms a fixed charge, and adversely affects the transistor characteristics. For this reason, it has been studied to keep nitrogen away from the silicon substrate interface. In particular, the High-k film easily diffuses nitrogen, and within the range we have tried, the higher the concentration of nitrogen in the film, the higher the diffusion concentration of nitrogen at the interface. For example, as shown in FIG. 7B, when nitrogen is added so that the nitrogen concentration is about 20%, the nitrogen concentration is close to 5% at the silicon substrate interface. This causes the transistor to operate correctly. Is an unacceptable concentration.
Here, the nitrogen concentration is generally obtained by the following equation.
Nitrogen concentration (%)
= {(Total number of atoms of nitrogen element per unit volume (pieces / cm ³ ) /
(Total number of atoms of all elements contained in the film per unit volume (pieces / cm ³ )} × 100
(Formula 1)
However, since it is difficult to actually measure the total number of atoms of all elements contained in the film, in general, the nitrogen concentration is approximately obtained by the following equation.
Nitrogen concentration (%)
= {(Total number of atoms of nitrogen element per unit volume (pieces / cm ³ ) /
(Total number of atoms of Si single crystal per unit volume (pieces / cm ³ )} × 100
(Formula 2)
The total number of atoms of Si single crystal per unit volume (pieces / cm ³ ), that is, the density of Si single crystals is 5 × 10 ²² pieces / cm ^3, so at the peak of nitrogen concentration as shown in FIG. The total number of nitrogen elements per unit volume (pieces / cm ³ ), that is, the nitrogen density is 1 × 10 ²² pieces / cm ³ , and when the nitrogen concentration is obtained from the above equation 2, the nitrogen concentration in this case is It can be determined approximately as 20%. In the following description of the nitrogen concentration, reference is made to the nitrogen concentration obtained by this approximation.

  An object of the present invention is to provide a method for manufacturing a semiconductor device capable of solving the above-described problems of the prior art and reducing the nitrogen concentration at the interface between the substrate and the high-k film.

The first invention includes a step of forming a high-k film on a substrate, a step of forming a silicon nitride film on the high-k film, and the silicon nitride film by a plasma-activated nitrogen-containing gas. And nitriding the surface side (silicon nitride film side) of the High-k film.
In addition, it is preferable that nitrogen is present in the form of Hf-ON and no Hf-N is present in a metal oxide film such as HfO ₂ by introducing nitrogen into the High-k film. In addition, in a silicate film such as Hf _x Si _(1-x) O ₂ (a silicate, which is a general term for a compound composed of silicon dioxide and a metal oxide, which may contain hydrogen), a Si—N film is used. It is preferable that nitrogen is present in the form, and that there is no metal nitride such as Hf—N.

  When a silicon nitride film was formed at a low temperature on the High-k film and treated with plasma activated nitrogen (plasma nitridation), it was oxidized by the oxygen of the High-k film taken in during the silicon nitride film formation. A portion of the silicon nitride film can be renitrided. As a result, a reduction in dielectric constant due to an increase in the oxygen concentration in the silicon nitride film can be suppressed, and a reduction in the capacity of the entire gate insulating film can be suppressed. Further, the plasma-activated nitrogen loses energy while diffusing in the silicon nitride film, nitrogen is introduced at a high concentration near the interface between the silicon nitride film and the high-k film, and the high-k film Nitrogen diffusion is suppressed at the interface between the silicon nitride film and the high-k film, and a steep or steep nitrogen concentration profile can be formed from the interface between the silicon nitride film and the high-k film to the interface between the high-k film and the substrate. The nitrogen concentration at the interface between the film and the substrate can be greatly reduced. By introducing high-concentration nitrogen into the silicon nitride film side of the silicon nitride film and the high-k film on the high-k film, the interface between the polysilicon electrode and the high-k film can be stabilized. At the same time, it has the effect of preventing the diffusion of boron.

An example of the substrate is a silicon wafer. The High-k film is composed of a metal oxide and silicate. Examples of the metal oxide include ZrO ₂ , HfO ₂ , Al ₂ O ₃ , TiO ₂ , and Ta ₂ O ₃ . Examples of the silicate include ZrSiO ₄ and HfSiO ₄ . Examples of a method for forming a high-k film include MOCVD, ALD (Atomic Layer Deposition), and a method of repeatedly forming several MOCVD films and a film quality modification process using a remote plasma gas. Examples of the nitride film include silicon nitride films (SiN, Si ₃ N ₄ , Si _x N _y ). Examples of a method for forming the nitride film include a thermal CVD method and an ALD method. Examples of the plasma source for performing the plasma treatment include a remote plasma source and a modified magnetron type (MMT: Modified-Magnetron Type) plasma source. The contents are disclosed in Japanese Patent Laid-Open No. 2001-196354.
Examples of the plasma-activated nitrogen-containing gas include N ₂ ^* , NH ₃ ^* , NH ₂ ^* , and NH ^* ( ^* means plasma).

According to a second invention, in the first invention, formation of a high-k film on a substrate and formation of a silicon nitride film of 5 mm or less are repeated a plurality of times, and finally nitrogen gas or a compound gas plasma containing nitrogen is used. A method for manufacturing a semiconductor device, characterized in that nitriding is performed.
When the formation of the high-k film and the silicon nitride film or the silicon oxynitride film are alternately repeated, and finally plasma nitridation is performed, nitrogen is introduced into each high-k film except the lowermost layer, and each of the high-k films Can be made to have a high nitrogen concentration. Increasing the nitrogen concentration in each of the High-k films not only has an effect of preventing boron penetration, but also prevents an increase in leakage current due to crystallization of the High-k film due to high-temperature heat treatment in the subsequent process. It is.
However, in this case, if the lowermost High-k film has a high nitrogen concentration, nitrogen diffusion to the interface of the silicon substrate occurs, and there is a concern that the carrier mobility in the transistor channel portion may be lowered. It is preferable to make the film thicker or to lay an extremely thin SiO ₂ film under the lowermost High-k film.

A third invention is a method of manufacturing a semiconductor device according to the first or second invention, wherein a silicon nitride film having a thickness of 5 mm or less is formed even before the high-k film is formed on the substrate. .
If the silicon nitride film is formed before the high-k film is formed, the sandwich structure in which the high-k film is sandwiched between the silicon nitride films is formed. Therefore, the formation of the high-k film and the formation of the silicon nitride film are repeated. Can increase the nitrogen concentration of the entire High-k film. The purpose of increasing the nitrogen concentration of the entire High-k film is as described above. However, in the third invention, in order to prevent nitrogen diffusion to the silicon substrate interface, it is necessary to lay an extremely thin SiO ₂ film under the lowermost silicon nitride film.

According to a fourth invention, in the first invention, a silicon nitride film is formed on the High-k film, or in the second and third inventions, a stacked film of the High-k film and the silicon nitride film. After performing the nitriding treatment using the plasma of the nitrogen gas or the compound gas containing nitrogen, the oxidation treatment is performed using the plasma of the oxygen gas or the gas containing oxygen. A method for manufacturing a semiconductor device.
For example, in the case of a metal oxide film such as HfO ₂ , the plasma nitriding treatment of the High-k film is not aimed at nitriding Hf atoms in the HfO ₂ film, but creating an Hf-ON bond, or Introducing nitrogen atoms into the Hf film. In the case of a silicate film such as Hf _x Si _(1-x) O ₂ , the purpose is not to nitride Hf atoms but to create Si—N bonds. If the metal in the High-k film is nitrided by plasma nitriding to form a metal nitride film that is a conductor, the leakage current of the formed transistor may increase. In order to prevent this, if plasma oxidation is performed after plasma nitridation, a relatively unstable metal nitride film is selectively oxidized as compared with a silicon nitride film, resulting in a non-conductive metal oxide film. An increase in current can be prevented.
Nitrogen gas or a compound gas containing nitrogen includes N ₂ , NH ₃ , N ₂ O, NO, NO _{2 and the} like. Examples of oxygen gas or a compound gas containing oxygen include O ₂ , O ₃ , O ^* , and H ₂ O.

In the fifth invention, after the silicon nitride film is formed on the High-k film in the first invention, or the stacked film of the High-k film and the silicon nitride film is formed in the second and third inventions. After that, without performing nitriding treatment, an oxidation treatment is performed using a plasma of oxygen gas or a compound gas containing oxygen, and then using a plasma of nitrogen gas or a compound gas containing nitrogen. A semiconductor device manufacturing method characterized by performing nitriding treatment.
The plasma oxidation is performed first when the silicon nitride film and the high-k film are considered to contain many impurities. This is because the effect of the subsequent nitriding tends to appear when the H or C in the film is removed first by plasma oxygen.

According to a sixth invention, in the first to fifth inventions, the silicon nitride film is a gas containing silicon element (SiH ₂ C1 ₂ (DCS), HSi [N (CH ₃ ) ₂ ] ₃ (TrDMASi), or Si [N (CH ₃ ) ₂ ] ₄ (TDMASi)) and nitrogen or a compound gas containing nitrogen, or plasma of nitrogen or a compound gas containing nitrogen is alternately supplied. A method for manufacturing a semiconductor device is characterized by forming a film by an ALD method.

A seventh invention is a method for manufacturing a semiconductor device according to the fourth to sixth inventions, wherein the nitridation and oxidation treatment using plasma can be continuously carried out in the same reaction chamber.
Since nitridation and oxidation treatment using plasma can be carried out continuously using the same reaction chamber, it does not take much time and energy to treat the substrate surface, and does not re-contamination during substrate transfer.

An eighth invention is a method of manufacturing a semiconductor device according to any one of the first to seventh inventions, wherein the plasma treatment is performed using an MMT plasma source.
Since the plasma processing is performed using the MMT plasma source capable of adjusting the energy incident on the substrate, the controllability of the nitrogen concentration profile in the High-k film is improved.

A ninth invention is a method of manufacturing a semiconductor device according to any one of the first to eighth inventions, wherein the formation of the silicon nitride film and the high-k film can be continuously performed using the same reaction chamber.
Since the formation of the silicon nitride film and the high-k film can be continuously performed using the same reaction chamber, the processing of the substrate surface does not take much time and energy, and is not recontaminated during the transfer of the substrate.

A tenth invention is characterized in that, in the fourth to sixth inventions, the silicon nitride film and the high-k film and the oxidation and nitridation treatment using plasma can be continuously performed in the same reaction chamber. This is a method for manufacturing a semiconductor device.
Since silicon nitride film and high-k film formation and plasma oxidation and nitridation treatment can be performed continuously in the same reaction chamber, a lot of time and energy is applied to the treatment of the substrate surface. No recontamination during transport.

According to an eleventh aspect of the invention, there is provided a step of forming a high-k film on a substrate, and a gas containing oxygen, a gas containing active oxygen, or a gas containing oxygen and active oxygen after the formation of the high-k film. A step of forming a silicon oxide film using a gas containing the gas, and a step of performing a nitriding process using a plasma of a nitrogen gas or a compound gas containing nitrogen after the silicon oxide film is formed. This is a method for manufacturing a semiconductor device.
When a silicon nitride film is formed on the High-k film, the High-k film is exposed to a reducing atmosphere, and oxygen vacancies may be generated in the High-k film. However, when the silicon oxide film is formed on the high-k film and then nitrided, the surface of the high-k film is not directly exposed to the reducing atmosphere, and the above problem can be avoided.
Further, when the silicon oxide film is formed after the high-k film is formed, the interface with the polysilicon electrode formed later and the high-k film formed earlier are formed rather than the silicon nitride film. Reduction of fixed charge can be expected by reducing the number of unbound species at the interface. However, since the nitrogen concentration is lower in the case of nitriding the silicon oxide film than in the case of forming the silicon nitride film, the gate insulating film capacitance is reduced, but it is preferable to implement it within an allowable range.

In the step of forming the silicon oxide film, a gas containing Si element, a gas containing Si element and a gas containing oxygen, a gas containing active oxygen, or a gas containing oxygen and a gas containing active oxygen can be used. . Examples of the gas containing silicon element include DCS, SiH ₄ , TDMASi (Si [N (CH ₃ ) ₂ ] ₄ ), and TEOS (Si (OC ₂ H ₅ ) ₄ ). Examples of the gas containing oxygen include O ₂ , O ₃ , and H ₂ O. Examples of the gas containing active oxygen include O ⁻ (ion), O ⁺ (ion), and O ^* (radical).

According to a twelfth aspect, in the eleventh aspect, after a silicon oxide film is formed on the high-k film, an oxidation treatment is performed using plasma of an oxidizing gas or a compound gas containing oxygen, and then a nitrogen gas Alternatively, the semiconductor device manufacturing method is characterized in that nitriding is performed using plasma of a compound gas containing nitrogen.
By forming an extremely thin silicon oxide film on the high-k film, further oxidizing the silicon oxide film, and further nitriding, the same effect as in the case of oxidizing after nitriding can be expected.
Examples of the compound gas containing an oxidizing gas or oxygen include O ₂ , O ₃ , and H ₂ O.

A thirteenth invention is a method for manufacturing a semiconductor device according to the eleventh and twelfth inventions, wherein the silicon oxide film and the high-k film can be continuously processed in the same reaction chamber.
Since the silicon oxide film and the high-k film can be continuously processed using the same reaction chamber, the processing of the substrate surface does not take much time and energy, and is not recontaminated during the transfer of the substrate.

According to a fourteenth aspect of the invention, there is provided the semiconductor device according to the eleventh aspect, wherein the silicon oxide film and the high-k film and the nitriding treatment using plasma can be continuously performed in the same reaction chamber. It is a manufacturing method.
Since the silicon oxide film and high-k film formation and plasma processing can be performed continuously in the same reaction chamber, a lot of time and energy is applied to the processing of the substrate surface. There is no recontamination.

A fifteenth aspect of the invention is a method for manufacturing a semiconductor device according to any of the first to fourteenth aspects of the invention, wherein the plasma treatment is performed using an MMT plasma source.
Since plasma processing is performed using an MMT plasma source capable of adjusting energy incident on the substrate, the controllability of the concentration profile is improved.

  According to the present invention, the nitrogen concentration at the interface between the substrate and the High-k film can be reduced, and the characteristics of the semiconductor device can be improved.

Embodiments of the present invention will be described below.
FIG. 3 shows a processing chamber in which a High-k film and a silicon nitride film are formed. FIG. 4 shows a processing chamber for performing plasma nitriding. FIG. 5 shows a single wafer cluster system for processing substrates continuously without exposing them to the atmosphere.

  As shown in FIG. 5, a plurality of chambers for processing a wafer as a silicon substrate are airtightly arranged on the outer periphery of the vacuum transfer chamber 300. The plurality of chambers include first and second substrate cooling chambers 311 and 312, a processing chamber (hereinafter referred to as a first processing chamber) 313 having a remote plasma source, and a processing chamber (hereinafter referred to as a second processing chamber) having an MMT plasma source. Chamber) 314, and first and second load lock chambers 315 and 316. The vacuum transfer robot 301 provided in the vacuum transfer chamber 300 has an arm so that the wafer can be transferred to or taken out from any of the plurality of chambers 311 to 316 described above. In addition, first and second cassette stands 331 and 332 for carrying in or carrying out wafer cassettes (or hoops) 341 and 342 are provided. An atmospheric transfer chamber 320 including an atmospheric transfer robot (not shown) is provided between the cassette stands 331 and 332 and the load lock chambers 315 and 316. The atmospheric transfer robot has an arm, and exchanges wafers between the cassette stands 331 and 332 and the load lock chambers 315 and 316.

  A wafer is carried into the first load lock chamber 315 from the cassette 341 of the first cassette stand 331 by the atmospheric transfer robot. A wafer is received from the first load lock chamber 315 by the vacuum transfer robot 301 in the vacuum transfer chamber 300 and is loaded into the first processing chamber 313 or the second processing chamber 314 to process the wafer. When the processing of the wafer is completed, the wafer is received by the vacuum transfer robot 301 and is loaded into the second processing chamber 314 or the first processing chamber 313 to continuously process the wafer. When the wafer processing is completed, the wafer is received by the vacuum transfer robot 301 and carried into the substrate cooling chamber 311 or 312. After cooling, the wafer is taken out of the substrate cooling chamber 311 or 312 by the vacuum transfer robot 301 and transferred to the second load lock chamber 316. The wafer is taken out from the second load lock chamber 316 by the atmospheric transfer robot, and is discharged to the cassette 342 of the second cassette stand 332.

  By repeating the above-described operation, unprocessed substrates are sequentially taken out from the cassette 341 of the first cassette stand 331, processed as described above, and stored in the cassette 342 of the second cassette stand 332 as processed substrates. .

  The first processing chamber shown in FIG. 3 is a single-wafer substrate processing chamber (hereinafter referred to as a CVD processing chamber) in which a high-k film or a silicon nitride film is formed on the surface of a wafer using a chemical reaction.

  When the wafer 200 is unloaded via the flat cylindrical chamber 102, the gas introduction part 136, the gas exhaust pipe 135, the substrate loading / unloading port (not shown), and the substrate loading / unloading chamber. Further, the heater unit 117 moves the wafer 200 in the chamber 102 between the substrate loading / unloading position where the wafer 200 is located and the substrate processing position where the wafer 200 is processed, and the heater unit 117 moved to the substrate loading / unloading position. And a pin 120 to be used. The heater unit 117 has a heater inside, and heats the wafer 200 on the heater unit 117. When the heater unit 117 moves to the substrate processing position in the chamber 102, the conductance for guiding the gas to the exhaust pipe 135 is regulated by restricting the flow of the gas into the space 105 formed below the heater unit 117. A plate 110 is provided.

  The substrate loading / unloading port of the CVD processing chamber is arranged on the side connected to the vacuum transfer chamber 300 of the single wafer cluster system shown in FIG. 5, from which the wafer 200 is transferred into the chamber 102 by the arm of the vacuum transfer robot 301. . At this time, when the heater unit 117 moves to the lower substrate loading / unloading position, the support pins 120 appear from the insertion holes provided in the heater unit 117, and the vacuum transfer robot 301 places the wafer 200 on the support pins 120. After the transfer robot 301 is retracted from the chamber 102, the heater unit 117 moves to the upper substrate processing position and scoops the wafer 200 onto the heater unit 117. The wafer 200 is heated to a temperature suitable for film formation by the heater unit 117. After the wafer temperature reaches a predetermined temperature, a raw material for processing is introduced from the gas introduction unit 136 onto the wafer 200 and is exhausted from the gas exhaust pipe 135.

  As shown in FIG. 3, the gas introduction unit 136 includes a plurality of introduction ports disposed adjacent to the upper portion of the chamber 102. In the illustrated example, a High-k source introduction port 137 for supplying a High-k film source gas, a plasma introduction port 138 for introducing a plasma gas generated by the plasma generator 130, a Si source introduction for supplying a Si source gas, etc. It consists of three ports 139. For example, nitrogen plasma is supplied from the plasma inlet 138. A High-k film is formed on the wafer 200 by supplying the High-k film source gas, and a silicon nitride film is formed on the wafer 200 by supplying the Si source gas and nitrogen plasma.

  The second processing chamber shown in FIG. 4 is a single-wafer substrate processing chamber (hereinafter referred to as an MMT processing chamber) in which a thin film formed on a substrate surface is subjected to nitriding treatment or oxidation treatment using high-density plasma generated by an electric field and a magnetic field. ).

The MMT processing chamber includes a chamber 202 composed of a lower container 211 and an upper container 210, a gas introduction part 236 having a shower plate 240, a gas exhaust pipe 235, a substrate loading / unloading port (not shown), a substrate A susceptor 217 that moves the wafer 200 in a chamber 202 between a substrate loading / unloading position where the wafer 200 is positioned and a substrate processing position where the wafer 200 is processed when the wafer 200 is unloaded via the loading / unloading port; And a pin (not shown) protruding from the susceptor 217 moved to the processing position. The susceptor 217 is grounded via an impedance adjustment circuit 274 in which a capacitor and a coil are connected in series, and the energy incident on the wafer 200 can be adjusted by controlling the potential of the wafer 200 via the susceptor 217. The susceptor 217 has a heater inside and heats the wafer 200 on the susceptor 217. The gas introduction part 236 has a plurality of reaction gas introduction ports. These are, for example, the N ₂ gas inlet 231 and the O ₂ gas inlet 232.

  A discharge cylindrical electrode 215 is installed on the outer periphery of the chamber 202, and high-frequency power from the high-frequency power source 273 is applied to the cylindrical electrode 215 via the matching unit 272 to generate plasma 224 in the processing chamber 201. It is like that.

  A magnetic field forming means 216 for forming a magnetic field is installed on the outer periphery of the chamber 202 so as to form a magnetic field in the cylindrical axis direction along the inner peripheral surface of the cylindrical electrode 215.

The substrate loading / unloading port of the MMT processing chamber is disposed on the side connected to the vacuum transfer chamber 300 of the cluster system shown in FIG. 5, and the wafer 200 is transferred from here to the chamber 202 by the arm of the vacuum transfer robot 301. At that time, the susceptor 217 moves to the lower substrate loading / unloading position, the support pins appear from the insertion holes provided in the susceptor 217, and the vacuum transfer robot places the wafer 200 on the support pins. After the transfer robot retreats from the chamber 202, the susceptor 217 moves to the upper substrate processing position and scoops up the wafer 200 onto the susceptor 217. The wafer 200 is heated to a temperature suitable for film formation by the susceptor 217. After the wafer temperature reaches a predetermined temperature, when high-frequency power is applied to the cylindrical electrode 215 and gas is introduced onto the wafer 200 from the gas introduction unit 236, the magnetron is affected by the magnetic field of the magnetic field forming means 216. Discharge occurs. As a result, charges are trapped in the space above the wafer 200 to generate high-density plasma, and the generated plasma gas processes the wafer 200. For example, when the gas is nitrogen N ₂ , nitrogen plasma nitrides the wafer 200, and when the gas is oxygen O ₂ , O ₃ (ozone), O ⁻ (ion), O ⁺ (ion), O ^* (Radical) oxidizes the wafer. At this time, the exhaust gas in the chamber 202 is exhausted from the gas exhaust pipe 235. Note that high-density plasma generated in the MMT processing chamber is referred to as MMT plasma.

  Next, a process of a semiconductor device manufacturing method using the above-described CVD processing chamber and MMT processing chamber will be described.

Here, a silicon oxide film is formed on the wafer 200 using the CVD processing chamber shown in FIG. 3, and a high-k film is formed thereon, for example, 20 to 30 mm, and the same CVD processing chamber is used. A silicon nitride film of about 5 mm is formed on the high-k film using a gas containing silicon element and a compound gas containing nitrogen, and nitrogen gas or nitrogen is added using the MMT treatment chamber shown in FIG. The process of nitriding the silicon nitride film using the plasma of the contained compound gas and nitriding the silicon nitride film side of the high-k film will be described. Note that a silicon oxynitride film may be formed on the high-k film instead of the silicon nitride film.
Here, the silicon nitride film side of the high-k film means a depth of about 5 to 10 mm (physical film thickness) from the interface with the silicon nitride film.

The reason why the thickness of the silicon nitride film is 5 mm is as follows.
It is assumed that the silicon oxide film (SiO ₂ ) equivalent film thickness (referred to as EOT) of the entire insulating capacitance film as a target is about 15 mm.
That is, a silicon oxide film (interface layer) is usually formed on a silicon substrate, a high-k film is formed thereon, and a silicon nitride film is formed thereon. These silicon oxide films (interface layer) The high-k film and the silicon nitride film are the entire insulating capacitance film, and the total of these EOTs is 15 mm.
First, on average, a silicon oxide film (interface layer) is formed with a thickness of 6 mm. Since this is a silicon oxide film, it is naturally equivalent to 6 mm of EOT. Next, since the relative dielectric constant of the silicon nitride film is about 1.7 times that of the silicon oxide film, the EOT of the 5 nm silicon nitride film is about 3%. How to find
ε _(SiO2) / EOT = ε _(SiN) / d _(SiN)
Where ε _(SiO2) : silicon oxide film dielectric constant,
ε _(SiN) : Dielectric constant of silicon nitride film
d _(SiN) : can be obtained from the relational expression of the physical film thickness of the silicon nitride film.
Then, the EOT of the High-k film is 6cm.
Since the dielectric constant of the High-k film using about 3.3 times the HfSiO ₂ of SiO _2, a 20Å as physical thickness. How to find
ε _(SiO2) / EOT = ε _(High-k) / d _(High-k)
Where ε _(SiO2) : silicon oxide film dielectric constant,
ε _(High-k) : High-k dielectric constant
d _(High-k) : can be obtained from the relational expression of the physical film thickness of the High-k film.
If the thickness of the silicon nitride film is greater than 5 mm, the physical film thickness of the high-k film becomes 20 mm or less and becomes thin, so that the leakage current increases. Therefore, from the viewpoint of securing the physical film thickness of the High-k film, the silicon nitride film has to be 5 mm or less.

  First, a silicon oxide film is formed on a wafer and a high-k film is formed thereon using a CVD processing chamber. In order to form a high-k film, an organic metal liquid raw material (hereinafter referred to as MO raw material) containing a metal such as Zr, Hf, Ti, Bi, La, Pr, or Al is generally vaporized as a high-k raw material. Or a metal halide vaporized by sublimation is used. The vaporized High-k raw material is introduced onto the wafer 200 from the High-k raw material introduction port 137.

The film formation method at this time may be any of MOCVD method, ALD method, or repeated film formation method of several MOCVD film formation and film quality modification treatment with remote plasma gas.
For example, in the case of MOCVD, film formation is performed at a wafer temperature of 500 to 300 ° C. (heater temperature is about 600 to 350 ° C.), a furnace pressure of 10 to 1000 Pa, and a high-k raw material of 0.001 to 0.1 g / min. is doing.

In the case of the ALD method, a high-k raw material and an oxidizing agent are alternately supplied using a CVD processing chamber. As the High-k raw material, the MO raw material or the metal halide is used as in the case of MOCVD, and is introduced onto the wafer 200 from the High-k raw material introduction port 137. As the oxidant, oxygen remote plasma generated by the plasma generator 130 may be introduced from the plasma inlet 138 shown in the figure, or water or ozone (O ₃ ) may be introduced from a separately provided inlet (not shown). ) Etc. may be introduced.

When the ALD method is performed using the MO raw material, the conditions at that time are as follows: the wafer temperature is 100 to 451 ° C. (heater temperature is about 150 to 600 ° C.), and the furnace pressure is 1 to 100 Pa.
(1) A High-k source gas is supplied from the High-k source inlet 137 onto the wafer 200 for 0.01 to 1.0 seconds and adsorbed on the wafer surface.
(2) Ar gas is supplied onto the wafer 200 from the same High-k raw material introduction port 137 for 0.1 to 1.0 seconds to purge excess High-k raw material gas through the exhaust pipe 135.
(3) O ₃ is supplied from the plasma inlet 138 onto the wafer 200 for 0.1 to 1.0 seconds to cause a surface reaction with the High-k raw material to form a High-k film.
(4) Ar gas is supplied onto the wafer from the same plasma inlet 138 for 0.1 to 1.0 seconds to purge excess O ₃ through the exhaust pipe 135.
The film is formed by a method in which one cycle including the four steps described above is repeated until the target film thickness is reached.

Subsequently, a silicon nitride film is formed on the High-k film using the same CVD processing chamber. In order to form the silicon nitride film, a thermal CVD method or an ALD method is used.
In the case of using the thermal CVD method, SiH ₂ Cl ₂ (DCS) is caused to flow from the Si raw material inlet 139 at a wafer temperature of 600 to 800 ° C., and plasma-treated NH ₃ (referred to as NH ₃ plasma) is caused to flow from the plasma inlet 138. React on the wafer surface. However, since it is difficult to control the film thickness in the thermal CVD method and there is a concern about the influence of the high temperature reducing atmosphere on the high-k film, the ALD method is suitable. The effect on the High-k film is, for example, when the High-k film is HfO ₂ , when heated to a high temperature, layer separation of HfO and SiO occurs, and HfO crystallizes at 500 ° C. or higher. Therefore, a leak current transmitted through the crystal grain boundary flows.

When the ALD method is performed using DCS and NH ₃ , the conditions at that time are as follows: the wafer temperature is 300 to 600 ° C. (heater temperature is about 400 to 700 ° C.), and the furnace pressure is 1 to 100 Pa.
(1) DCS is supplied onto the wafer 200 from the Si raw material inlet 139 for 0.01 to 1.0 seconds and adsorbed on the wafer surface.
(2) Ar gas is supplied onto the wafer 200 from the same Si source inlet 139 for 0.1 to 1.0 seconds to purge excess DCS through the exhaust pipe 135.
(3) NH ₃ plasma is supplied from the plasma inlet 138 onto the wafer 200 for 0.1 to 5.0 seconds to cause a surface reaction with DCS to form a silicon nitride film.
(4) Ar gas is supplied onto the wafer from the same plasma inlet 138 for 0.1 to 1.0 seconds to purge excess NH ₃ plasma through the exhaust pipe 135.
The film is formed by a method in which one cycle including the four steps described above is repeated until the target film thickness is reached.

Examples of the silicon nitride film formed here include SiN, Si ₃ N ₄ , and Si _x N _y . In general, the composition of a CVD film at a high temperature or a silicon nitride film thermally nitrided at a high temperature is: Si ₃ N ₄ is obtained. However, the composition is considered unstable in a low temperature process such as ALD or MOCVD. In addition, the plasma nitrided nitride film is considered not to have a composition of Si ₃ N ₄ . Further, when the silicon nitride film is an ultra-thin film having a thickness of 10 mm or less, or when it has a laminated structure with a high-k film, mutual diffusion occurs between the upper and lower layers by heat treatment, and the composition is from Si ₃ N _4. It is thought that it has come off. Therefore, it is simply expressed as a silicon nitride film here.

  Next, the silicon nitride film formed on the high-k film is nitrided using an MMT apparatus. This nitriding treatment is performed by nitriding the silicon nitride film using plasma of nitrogen gas or a compound gas containing nitrogen. When the high-k film is directly irradiated with nitriding plasma, the activated nitrogen diffuses deeply in the high-k film and reaches the silicon substrate interface, which may cause a defect in the channel portion of the transistor. By irradiating the silicon nitride film formed on the −k film with nitrogen plasma, the diffusion energy in the silicon nitride film can be weakened and introduced into the high-k film, so that nitrogen atoms can reach the silicon substrate interface. There is an advantage that diffusion can be prevented. The second reason for irradiating the silicon nitride film with nitrogen plasma is to eliminate impurities that may be contained in the silicon nitride film formed by the low temperature process.

As a device for nitriding a silicon nitride film, a CVD processing chamber or an MMT processing chamber is used.
In the case of using a CVD processing chamber, nitriding can be continuously performed using the same processing chamber as that using the High-k film and the silicon nitride film. However, the MMT processing chamber is more suitable than the CVD processing chamber in terms of uniformity of nitriding processing.

In the case of using the MMT processing chamber shown in FIG. 4, the wafer temperature is room temperature to 700 ° C., is introduced from the N ₂ gas inlet 231 and N ₂ from the injection holes 241 of the shower plate 240 like a shower. The pressure at this time is 1 to 200 Pa. At the same time, high frequency power is applied to the cylindrical electrode 215 from the high frequency power supply 273 via the matching unit 272. The silicon nitride film formed on the wafer 200 on the susceptor 217 is nitrided by the generated high-density nitrogen plasma.

  In this way, a high-k film is formed on the wafer, a silicon nitride film is formed on the high-k, and the silicon nitride film is further nitrided to nitride the high-k film surface.

In the above-described embodiments, it has been described that the silicon nitride film is simply subjected to the nitriding process in the MMT processing chamber. However, it is preferable that the high-k film pre-processing and post-processing are performed in the MMT processing chamber. Process once. That is, as the pretreatment, the silicon substrate 400 is oxidized to form the interface SiO ₂ film 411 (see FIG. 1), and as the posttreatment, the silicon nitride film formed on the high-k film is nitrided.
Here, the interface SiO ₂ film is formed before the high-k film is formed, for example, by RTP (Rapid Thermal Process), MMT plasma, or by oxidation (chemical oxide) by chemical solution treatment. The film thickness is about 6-8 mm.

A semiconductor device structure manufactured by the above-described method including pre-processing and post-processing is shown in FIG.
A gate region 410 partitioned by an element isolation region 401 is formed on the surface of the substrate 400. On the gate region 410, a silicon oxide film 411, a high-k film (for example, HfO ₂ ) 412, a silicon nitride film 413, and a polysilicon electrode 415 are sequentially formed to constitute a gate portion 420. The outer periphery of the gate portion 420 is covered with an interlayer insulating film 405. An n ⁺ type source region 402 and a p ⁺ type drain region 403 are arranged on the surface of the substrate 400 on both sides of the gate region 410 by ion implantation or the like. A protective film 406 is formed over the entire surface of the substrate 400 including the gate portion 420 and the interlayer insulating film 405.
As shown in FIG. 2 showing one process of the manufacturing method according to the first embodiment, the silicon oxide film 411 is oxidized by the pretreatment in the MMT processing chamber (step 1). The high-k film 412 thereon is formed in the CVD processing chamber by MOCVD or ALD, by repeating MOCVD and modification, etc. (step 2). The silicon nitride film 413 on the high-k film 412 is formed by ALD or thermal CVD in the CVD process chamber (step 3). The silicon nitride film 413 is nitrided by post-processing in the MMT processing chamber (step 4).

According to the first embodiment, as shown in FIG. 1A, the High-k film 412 is formed on the SiO ₂ layer (interface SiO ₂ layer) 411 which is the base film on the silicon substrate 400, and the High− At the stage where an ultra-thin silicon nitride film 413 is formed on the surface of the k film 412, nitrogen N ₂ remains only in the silicon nitride film 413 and does not diffuse into the high-k film 412. However, as shown in FIG. 1B, when the silicon nitride film 413 is nitrided with nitrogen plasma Pn in the MMT processing chamber, the overflow of the nitrogen from the silicon nitride film 413 causes the high-k film 412 to flow. Since the surface is nitrided, as the High-k film, the interface between the silicon nitride film 413 and the High-k film 412 has the highest nitrogen concentration, and the nitrogen concentration decreases in the depth direction of the High-k film. A profile is formed so that the nitrogen concentration is the lowest at the interface between the k film 412 and the SiO ₂ 411. At the peak of the nitrogen concentration, the nitrogen density is about 1 × 10 ²² pieces / cm ³ , and the nitrogen concentration is about 20%.

  In particular, in the nitriding process, by using an MMT processing chamber capable of adjusting the energy incident on the silicon nitride film 413, the controllability of the nitrogen concentration profile can be improved. Therefore, even if the nitrogen concentration on the silicon nitride film side of the high-k film 412 is increased, the diffusion concentration of nitrogen to the silicon oxide film interface does not increase, and the nitrogen concentration at the silicon oxide film interface can be effectively lowered. As a result, the transistor can be operated correctly.

Further, since the high-k film and the silicon nitride film are formed in the same CVD processing chamber, recontamination of the wafer surface is minimized as compared with the case where the film is exposed to the air in the middle. Therefore, it is possible to form a high-quality interface layer without spending much time and energy on the modification process of the substrate surface as in the prior art and without re-contamination during substrate transport. Further, if the same CVD processing chamber is used, the number of chambers provided in the single wafer cluster system can be reduced, so that the footprint (installation area) of the apparatus can be reduced, and the apparatus cost can be reduced. Moreover, since each process is performed in the same CVD process chamber, the pre-process can be performed using the conventional wafer heating time in the CVD process chamber.
If there is a request for device manufacturing, the High-k film and the silicon nitride film may be processed discontinuously using two different CVD processing chambers.

  In the first embodiment, the high-k film and the silicon nitride film and the nitriding process using plasma are performed in different processing chambers. However, the high-k film and the silicon nitride film are formed. It is also possible to perform nitriding using plasma in the same processing chamber. In order to perform a series of processing in the same processing chamber, the MMT processing chamber shown in FIG. 4 is commonly used, and the source gas is introduced from the gas introduction section 236 provided above the processing chamber. In this case, the volume of the MMT processing chamber is larger than that of the CVD processing chamber for forming the High-k film or silicon nitride film shown in FIG. 3, and it is necessary to lengthen the purge step in one cycle of the ALD method. Sex is not good. However, when manufacturing a semiconductor device that is not suitable for mass production, the introduction cost of the device can be reduced.

  Further, in Example 1, a high-k film, a silicon nitride film, or a silicon oxynitride process is performed using a single wafer processing chamber. In the case where film formation processing in one process such as a semiconductor memory is performed with high throughput, it is advantageous to use a vertical processing chamber capable of batch processing a plurality of sheets. However, in the case of in-situ, that is, when it is desired to perform processing continuously without exposure to the atmosphere, the single wafer cluster system described above is considered advantageous.

The formation of the high-k film on the silicon oxide film formed on the wafer of Example 1 and the formation of the silicon nitride film of 10 mm or less were repeated a plurality of times to form a stacked film of the high-k film and the silicon nitride film. The same as Example 1 except that a multilayer structure was adopted.
When the formation of the high-k film 412 and the silicon nitride film 413 is repeated a plurality of times, a nitrogen concentration profile as shown in FIG. 8A is obtained, but plasma nitridation and heat treatment performed thereafter result in FIG. 8B. Nitrogen N ₂ can be introduced into the entire film to increase the nitrogen concentration.

By thus high concentrations of nitrogen enters the High-k film except for the lowermost layer of High-k film, effectively prevents the penetration of boron to diffuse into the polysilicon layer to the gate electrode to the p ⁺ -type be able to.
Further, when the High-k film 412 is composed of Hf atoms and HfO ₂ molecules, if these Hf atoms and HfO ₂ molecules are aggregated, it causes a leakage current that propagates through the grain boundary due to crystallization and deteriorates the device characteristics. I will let you. However, when the high-k film and the silicon nitride film are repeatedly formed as in the second embodiment so that nitrogen N ₂ enters the entire high-k film, the high-k film 412 is heat treated. When, for example, heat of 1000 ° C. or higher is applied in activation annealing after ion plantation, for example, aggregation of Hf atoms and HfO ₂ molecules can be effectively prevented.

Example 2 was the same as Example 2 except that a silicon nitride film of 10 mm or less was formed before the formation of the High-k film on the silicon oxide film formed on the wafer of Example 2.
In this embodiment, even in the case of a thin film that uses only three steps of the silicon nitride film 413, the high-k film 412, and the silicon nitride film 413, a sandwich structure in which the high-k film is sandwiched between the nitride films is formed. A nitrogen profile as shown in FIG. 9 can be expected.

After performing nitriding treatment using the nitrogen gas or the compound gas plasma containing nitrogen in Examples 1, 2, and 3, the oxidation treatment is performed using the oxygen gas or the plasma of the compound gas containing oxygen. Except for this point, it was the same as Examples 1, 2, and 3.
The nitriding conditions in the MMT processing chamber at this time are a pressure of 1 to 200 Pa, an introduced gas N ₂ , and a wafer temperature of room temperature to 700 ° C. Further, the oxidation treatment conditions are a pressure 1～200Pa, mixed gas, the wafer temperature of the introduced gas O _2, or K _r and O ₂ is room temperature to 700 ° C..
When the nitriding treatment and the oxidation treatment are performed in this order as in this embodiment, the transition metal oxide film constituting the High-k film or the like becomes a conductor when nitriding, and becomes a source of leakage current. . However, since this conductor is relatively unstable, if the conductor is later weakly oxidized, it returns to the metal oxide film, and the cause of the leakage current can be eliminated. For example, when the High-k film is HfO ₂ , it may become HfN by nitriding treatment, but when it becomes HfN, it crystallizes and propagates through the grain boundary, but if plasma oxidation treatment is performed, Returning to HfO ₂ , no leakage current occurs.

After forming the silicon nitride film on the High-k film of Example 1, or after forming the stacked film of the High-k film and the silicon nitride film of Example 2 and Example 3, without performing nitriding treatment, Oxidation treatment is performed using plasma of oxygen gas or a compound gas containing oxygen in the MMT treatment chamber, and thereafter, plasma of nitrogen gas or compound gas containing nitrogen is used in the same MMT treatment chamber. The same as Examples 1, 2, and 3 except that the nitriding treatment was used.
Plasma oxidation process conditions in MMT treatment chamber at this time pressure 1～200Pa, mixed gas, the wafer temperature of the introduced gas O _2, or K _r and O ₂ is room temperature to 700 ° C.. The nitriding conditions are a pressure of 1 to 200 Pa, an introduced gas N ₂ , and a wafer temperature of room temperature to 700 ° C.
When the silicon nitride film is oxidized, the Si—H and N—H bonds in the silicon nitride film are reduced, and the High-k film is oxidized with oxygen O ₂ diffused deeply.
This oxidation treatment is performed by oxidizing the silicon nitride film using plasma of oxygen gas or a compound gas containing oxygen. When the high-k film is directly irradiated with oxygen plasma, the activated oxygen diffuses in the high-k film and the silicon oxide film, reaches the silicon substrate interface, and oxidizes the silicon substrate. The film thickness is increased, the EOT is also increased, and the desired EOT cannot be obtained. By irradiating the silicon nitride film formed on the high-k film with oxygen plasma, the diffusion energy in the silicon nitride film can be weakened and introduced into the high-k film. Has the advantage that it can be prevented from spreading.

  A silicon oxide film is formed on the wafer using the CVD processing chamber shown in FIG. 3, a high-k film is formed on the silicon oxide film, and a silicon element is formed on the high-k film using the same CVD processing chamber. A silicon oxide film is formed using a gas containing, a gas containing silicon element and a gas containing oxygen, an oxygen gas, a gas containing active oxygen, or a gas containing oxygen and a gas containing active oxygen, and FIG. A process of nitriding a high-k film surface by nitriding a silicon oxide film using a plasma of nitrogen gas or a compound gas containing nitrogen using the MMT processing chamber shown in FIG.

A High-k film is formed on the wafer by the same method as in the first embodiment. Thereafter, a silicon oxide film is formed on the high-k film. In order to form the silicon oxide film, an ALD method or a thermal CVD method is used.
For example, ALD film formation by alternately supplying Si [N (CH ₃ ) ₂ ] ₄ (hereinafter abbreviated as TDMASi) and O ₃ , or CVD film formation by simultaneously supplying Si (OC ₂ H ₅ ) ₄ and O ₂ is performed. is there.
In the case of ALD film formation by alternately supplying TDMASi and O ₃ or remote plasma O ₂ ,
(1) TDMASi is allowed to flow from the Si source inlet 139 of FIG. 3 for about 0.01 seconds to 10 seconds. At this time, the inside of the processing chamber is kept at a vacuum degree of about 1 to 100 Pa.
(2) Next, an inert gas such as N ₂ , Ar, He, Ne, _Kr or the like is supplied from the same Si raw material inlet 139 for about 0.01 to 10 seconds.
(3) Next, remote plasma O ₂ or O ₃ is allowed to flow from the plasma inlet 138 for about 0.01 to 10 seconds.
(4) Then from the same plasma introduction port 138, it flows approximately 0.01 to 10 seconds _{N 2, Ar, He, Ne} , an inert gas such as K _r. At this time, the temperature of the silicon substrate is about 150 ° C. to about 500 ° C.
The film is formed by a method in which one cycle including the four steps described above is repeated until the target film thickness is reached.
In this film formation, the ALD film is formed if the temperature is as low as 150 ° C. to 300 ° C., and the CVD film is formed at a high temperature of 300 ° C. or higher.

When the gas containing silicon element is Si (OC ₂ H ₅ ) ₄ (TEOS), the silicon substrate (Si wafer) temperature is kept at a high temperature of about 600 ° C. to 800 ° C., and TEOS is introduced into the Si raw material inlet. A film is formed by simultaneously introducing O ₂ from the plasma inlet 138 from 139.

  Next, the silicon oxide film is nitrided using plasma of nitrogen gas or a compound gas containing nitrogen. The nitriding treatment of the silicon oxide film is the same as the nitriding treatment of the silicon nitride film of the first embodiment.

  In this way, a silicon oxide film is formed on the wafer, a high-k film is further formed thereon, an ultrathin silicon oxide film is formed on the high-k film, and the silicon oxide film is further converted to nitrogen. By nitriding with plasma, the same effect as in Example 1 can be expected. In particular, when a silicon oxide film is used, the fixed charge can be reduced by a dangling bond at the interface with a polysilicon electrode to be formed later and the interface with a high-k film, as compared with the case where a silicon nitride film is used. I can expect.

  Also in the case of the sixth embodiment, as in the case of the first embodiment, the high-k film and the silicon oxide film can be continuously processed using the same CVD processing chamber. Further, the high-k film formation and the nitridation process using the silicon oxide film and plasma can be continuously performed using the same CVD process chamber or MMT process chamber.

  After a silicon oxide film is formed on the high-k film of Example 6, an oxidation treatment is performed using a plasma of an oxidation gas or a compound gas containing oxygen without performing a nitridation treatment, and then a nitrogen gas or Example 6 is the same as Example 6 except that nitriding is performed using a plasma of a compound gas containing nitrogen. The contents of the oxidation treatment and nitriding treatment are the same as those in the first embodiment, and the same effects as those in the fifth embodiment can be expected.

Example 1 or Example 6 was the same as Example 1 except that the silicon nitride film of Example 1 or the silicon oxide film of Example 6 was replaced with a silicon oxynitride film. That is, a step of forming a high-k film, a step of forming a silicon oxynitride film on the high-k film, and a plasma nitridation treatment of the silicon oxynitride film. Alternatively, plasma nitriding treatment is performed from the step of alternately forming the high-k film and the silicon oxynitride film a plurality of times and from the last film formed in this step.
Also in the case of the eighth embodiment, as in the first and sixth embodiments, the High-k film and the silicon oxynitride film can be continuously processed using the same CVD processing chamber. Further, the high-k film formation, the silicon oxynitride film, and the nitridation treatment using plasma can be continuously performed using the same CVD processing chamber or MMT processing chamber.

In the first and second embodiments, the silicon oxide film 411 is formed on the silicon substrate 400 and the high-k film 412 is formed thereon. In the first and second embodiments, the silicon substrate 400 is used. The nitrogen concentration was adjusted to 1% or less at the interface between the silicon oxide film and the silicon oxide film.
Note that the role of the silicon oxide film 411 in the first and second embodiments is to prevent the metal from diffusing from the high-k film to the silicon substrate 400, and no fixed charge is generated. Is for.
The first and second embodiments can be performed without using the silicon oxide film 411. In this case, the High-k film 412 is formed directly on the silicon substrate 400. In this case, the nitrogen concentration is set to 1% or less at the interface between the silicon substrate 400 and the High-k film 412.
However, the silicon oxide film (interface) 411 is an auxiliary role on the silicon substrate 400, and plasma nitridation is performed without forming a silicon nitride film, a silicon oxide film, or a silicon oxynitride film on the high-k film. Is not possible. That is, if a silicon oxide film 411 is formed on a silicon substrate 400, a high-k film is formed thereon, a silicon nitride film, a silicon oxide film, or a silicon oxynitride film is not formed thereon, and a plasma is formed. When nitriding is performed, the nitrogen element passes through the silicon oxide film (interface) 411 and reaches the silicon substrate 400, and the nitrogen concentration at the interface between the silicon substrate 400 and the silicon oxide film (interface) 411 is reduced. Therefore, the silicon oxide film (interface) 411 on the silicon substrate 400 is only an auxiliary role.
In the case of the third embodiment, unlike the first and second embodiments, since the silicon nitride film 413 is formed before the high-k film 412 is formed, there is no gap between the silicon substrate 400 and the high-k film. It is essential to provide a silicon oxide film. If not provided, naturally, the silicon substrate 400 and the silicon nitride film are in contact with each other, the nitrogen concentration at the interface becomes high, and the carrier mobility is lowered, so that desired device characteristics cannot be obtained.
In the sixth embodiment, the silicon oxide film 411 is provided on the silicon substrate 400 and the high-k film 412 is formed thereon. However, in the sixth embodiment, it is not essential to provide the silicon oxide film 411. .

It is explanatory drawing of the wafer structure and nitrogen concentration profile by embodiment, (a) is before nitriding, (b) is the figure after nitriding. It is process drawing of the manufacturing method of the semiconductor device by embodiment. It is a figure explaining the 1st processing chamber for enforcing the manufacturing method of the semiconductor device of the present invention, (a) is a sectional view and (b) is a top view. It is sectional drawing explaining the 2nd process chamber by embodiment. It is a top view of the single wafer cluster system for enforcing the manufacturing method of the semiconductor device of the present invention. It is sectional drawing of the transistor manufactured by the manufacturing method by embodiment. It is explanatory drawing of the wafer structure and nitrogen concentration profile by a prior art example, (a) is before direct plasma nitridation, (b) is a figure after nitriding. It is explanatory drawing of the wafer structure and nitrogen concentration profile by embodiment, (a) is before nitriding, (b) is the figure after nitriding. It is explanatory drawing after nitriding of the wafer structure and nitrogen concentration profile by embodiment.

Explanation of symbols

400 wafers (substrate)
411 Interface SiO ₂ film 412 High-k film (high dielectric film, ie, metal oxide film)
413 Nitride film Pn Nitrogen plasma

Claims (6)

Forming a metal oxide film or silicate film on the substrate;
On the metal oxide film or the silicate film, and forming one of a silicon insulating film of silicon nitride film, a silicon oxide film, or a silicon oxynitride film,
Plasma nitriding the silicon insulating film , and
In the plasma nitridation process, a plasma oxidation process is performed before the plasma nitridation process. And a metal oxide film or a silicate film on a substrate, forming a plurality of times and a silicon nitride film or a silicon oxynitride film alternately,
Plasma nitriding from the last film formed in the step ,
In the plasma nitridation process, a plasma oxidation process is performed before the plasma nitridation process. The semiconductor device according to claim 1 or 2, wherein the metal oxide film or the silicate layer is either formed directly on the substrate or via the silicon oxide film formed on the substrate, wherein the Turkey Production method. The semiconductor device according to claim 3, wherein a nitrogen concentration at an interface between the substrate and the metal oxide film or the silicate film, or an interface between the substrate and the silicon oxide film is 1% or less. Method. Forming a metal oxide film or silicate film on the substrate;
Forming a silicon insulating film of any one of a silicon nitride film, a silicon oxide film, and a silicon oxynitride film on the metal oxide film or the silicate film;
Performing a plasma nitridation process after performing a plasma oxidation process on the silicon insulating film, or performing a plasma oxidation process after performing a plasma nitridation process;
A method for manufacturing a semiconductor device, comprising: A metal oxide film or silicate film and a silicon nitride film or silicon oxynitride film are formed on the substrate.
The step of forming these laminated films by alternately forming a plurality of times,
A step of performing plasma nitriding treatment after performing plasma oxidation treatment on the laminated film, or performing plasma oxidation treatment after performing plasma nitriding treatment;
A method for manufacturing a semiconductor device, comprising:

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