JP2009152303A - Method of depositing insulating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To deposit an insulating film which is applicable as a high-dielectric-constant gate insulating film and can compatibly have a low EOT and a low interface state. <P>SOLUTION: A method of depositing an insulating film includes: a first step of depositing an Hf-Si film 102 on an Si substrate 101 by sputtering; a second step of depositing an HfSiO film 103 by oxidizing the Hf-Si film; and a third step of forming an HfSiON film 105 by nitriding the HfSiO film. In the second step, the Hf-Si film is irradiated with near ultraviolet light when the Hf-Si film is oxidized and a surface layer portion of the Si substrate is oxidized to form an SiO<SB>2</SB>film 104. The near ultraviolet light has a wavelength of 220 to 380 nm. As a light source for the near ultraviolet light, Kr<SB>2</SB>excimer lamp, KrF excimer lamp, XeCl excimer lamp, or XeF excimer lamp is used. In the second step, the Hf-Si film is oxidized using oxygen activated using plasma excitation, photoexcitation, or ozone supply. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an insulating film forming method, and more particularly to an insulating film forming method suitable for use as a high dielectric constant gate insulating film in a semiconductor device.

  A metal oxide semiconductor field effect transistor (MOSFET), which is one of the basic devices of most highly integrated circuits (LSI) formed on a semiconductor substrate, includes a source region, a drain region and a channel region formed in a semiconductor, It consists of a gate insulating film and a gate electrode. When a voltage equal to or higher than the threshold voltage (Vth) is applied to the gate electrode, a current flows in the channel region between the source region and the drain region, and the transistor is switched from OFF to ON.

In order to improve the operation performance of the LSI, it is necessary to reduce the LSI design rules. As the design rule is reduced, that is, the gate length (GL) of the transistor is reduced, the thickness (t _ox ) of the gate oxide film as the gate insulating film needs to be reduced (t _ox = 0.018GL). This is to maintain a high capacitance between the silicon substrate and the gate electrode.

As the gate oxide film becomes thinner, an SiO ₂ film that requires a physical film thickness of 1 nm (about 3 molecular layers) or less cannot be used as a gate oxide film because the leakage current increases.

Therefore, it is necessary to replace the SiO ₂ film with a new dielectric material having a high dielectric constant, and to use a thick film with little leakage current without lowering the capacitance.

Examples of the high dielectric constant (High-k) gate insulating film include those made of the following materials. In the present invention, a material having a high dielectric constant (High-k) refers to a material having a relative dielectric constant higher than the relative dielectric constant ε _r = 3.9 of SiO ₂ . That is, HfO ₂ , HfON, HfSiO, HfSiON, HfAlO, HfAlON, LaO ₂ , LaON, LaAlO ₃ , LaAlON, ZrO ₂ , ZrON, ZrSiO, ZrSiON, and the like.

  As a method for forming a high-k gate insulating film, a CVD method using an organic metal material as described in Patent Document 1, an atomic layer deposition (ALD) method, a sputtering method, and the like have been studied. Among these, the sputtering method is advantageous in that carbon impurities are less mixed into the formed gate insulating film.

Here, an example of the formation process using the sputtering method of the HfSiON film which is the most practical high-k gate insulating film will be described with reference to FIG. In FIG. 4, reference numeral 501 denotes an Si substrate, 502 denotes an Hf single metal film or Hf—Si mixed metal film, 503 denotes an HfSiO film, 504 denotes an SiO ₂ film, and 505 denotes an HfSiON film.

First, in the thermal oxidation step, a SiO ₂ film 504 having a thickness of 1 to ₂ nm is formed on the cleaned Si substrate 501 by a thermal oxidation method. Next, in the metal film deposition step, an Hf single metal film or an Hf—Si mixed metal film 502 is deposited on the SiO ₂ film 504 by sputtering. Next, in the oxidation step, the Hf single metal film or the Hf—Si mixed metal film 502 is oxidized using activated oxygen to form the HfSiO film 503. Thereafter, in the nitriding step, nitrogen is introduced into the HfSiO film 503 by plasma nitriding to form the HfSiON film 505. In the step of oxidizing the metal film 502, Hf atoms are diffused into the SiO ₂ film 504 to form a silicate layer. Finally, the low dielectric constant SiO ₂ film 504 is thinner than the initial film, and the high dielectric constant HfSiON is formed. A film 505 is formed. As a result, a film having an equivalent oxide thickness (EOT) smaller than that derived from the initial SiO ₂ thickness is formed. Here, the equivalent oxide film thickness (EOT) refers to a value obtained by converting the physical thickness of the high dielectric constant (High-k) film into an electrical film thickness equivalent to the SiO ₂ film.

However, the initial SiO ₂ film 504 that is difficult to below 1.2 nm, for there is a limit to diffusion into the SiO ₂ film 504 of Hf, ultimately thickness twelve underlying SiO ₂ film 504 It was difficult to reduce the thickness evenly, and it was difficult to reduce EOT.

As a method of realizing the thinning of the SiO ₂ film 504 under the HfSiON film 505, as shown in FIG. 5, the metal film 502 is directly deposited on the Si substrate 501 without performing thermal oxidation before the metal film 502 is deposited. There is a method of depositing 502 by sputtering.

First, in the metal film deposition step, an Hf—Si mixed metal film 502 as a metal film containing Hf is deposited on the Si substrate 501 by sputtering. Next, in the oxidation step, the Hf—Si mixed metal film 502 is oxidized using activated oxygen to form an HfSiO film 503. Thereafter, in the nitriding step, nitrogen is introduced into the HfSiO film 503 by plasma nitriding to form the HfSiON film 505. When the metal film 502 is oxidized, the surface layer portion of the underlying Si substrate 501 is also oxidized, and an extremely thin SiO ₂ film 504 is formed as compared with the method of FIG. 4 in which the initial SiO ₂ film 504 is formed. . As a result, a film having an extremely small equivalent oxide thickness (EOT) can be obtained.
JP 2004-140292 A

However, in the method of forming the High-k gate insulating film of FIG. 5 in which the metal film 502 is directly formed on the Si substrate 501 without using the thermal oxide film, a sufficiently low EOT can be obtained, but the following problems are encountered. was there. That is, since the SiO ₂ film 504 under the HfSiON film 505 is too thin, a good SiO ₂ / Si interface is not formed, and the interface state may increase.

  SUMMARY OF THE INVENTION In view of the above technical problems, the present invention aims to form an insulating film that is suitable for use as a high dielectric constant gate insulating film and can achieve both a low EOT and a low interface state. .

  According to the present invention, the following method for forming an insulating film is provided to achieve the above object. That is, this method is a method of forming an insulating film on a silicon substrate, and includes a first step of forming a metal film on the silicon substrate, and oxidizing the metal film to include metal and oxygen. A second step of forming a film. This method is characterized in that, in the second step, when the metal film is oxidized, the metal film is irradiated with near ultraviolet light to oxidize a surface layer portion of the silicon substrate to form the silicon oxide film. And

  In one aspect of the present invention, the method includes a third step of nitriding the film containing the metal and oxygen formed in the second step to form a film containing the metal, oxygen, and nitrogen. . In one aspect of the present invention, the metal is at least one of Hf, Al, La, Zr, Ta, and Y. In one embodiment of the present invention, the metal film includes silicon in addition to the metal.

In one aspect of the present invention, the near-ultraviolet light has a wavelength of 220 to 380 nm. In one embodiment of the present invention, at least one of a Kr ₂ excimer lamp, a KrF excimer lamp, a XeCl excimer lamp, and a XeF excimer lamp is used as the near-ultraviolet light source.

  In one embodiment of the present invention, the metal film is oxidized using activated oxygen in the second step. In one embodiment of the present invention, the activated oxygen is activated using at least one of plasma excitation, photoexcitation, and ozone supply. In one aspect of the present invention, the metal film is formed by sputtering in the first step.

  According to the present invention, it is possible to form an insulating film that is suitable for use as a high dielectric constant gate insulating film and can achieve both a low EOT and a low interface state.

  Hereinafter, embodiments of a method for forming an insulating film according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a process cross-sectional view for explaining an embodiment of a method for forming an insulating film according to the present invention. FIG. 2 is a schematic cross-sectional view of an apparatus used for carrying out the method for forming an insulating film according to the present invention. In these drawings, reference numeral 101 denotes a silicon substrate, that is, a Si substrate, and reference numeral 102 denotes an Hf single metal film as a metal film or a mixed metal film of Hf and Si (Hf-Si film). Reference numeral 103 denotes a HfSiO film (Hf silicate film) as a film containing metal, oxygen and silicon as a film containing metal and oxygen, and 104 denotes a silicon oxide film, that is, a SiO ₂ film. Reference numeral 105 denotes an HfSiON film (nitride Hf silicate film) as a film containing metal, oxygen, nitrogen and silicon as a film containing metal, oxygen and nitrogen. 111 is an oxidation treatment chamber, 112 is a substrate support, 113 is a gas introduction means, 114 is an exhaust means, 115 is a dielectric tube, 116 is a power supply means, 117 is a light transmission window, and 118 is a near-ultraviolet illumination system. It is.

The insulating film is formed by the HfSiON film 105 and the SiO ₂ film 104. Here, the presence of the SiO ₂ film 104 improves the interface characteristics and enhances the electrical insulation of the insulating film. However, the SiO ₂ film 104, and the specific dielectric constant is smaller than the HfSiON film 105, the film thickness of the SiO ₂ film 104 is preferably smaller than the thickness of the HfSiON film 105. In order to improve the SiO ₂ / Si interface characteristics and obtain a low interface state, the thickness of the SiO ₂ film 104 is preferably 0.3 nm or more, and in order to keep the EOT of the insulating film low, the SiO ₂ film The film thickness of 104 is preferably 0.9 nm or less.

   First, in a metal film deposition step (first step of forming a metal film on a silicon substrate), an Hf-Si film 102 as a metal film containing silicon is deposited on the cleaned Si substrate 101 by sputtering. To do. According to the sputtering method, a metal film in which impurities such as carbon impurities are hardly mixed can be formed.

Next, in the oxidation step (second step of oxidizing the metal film to form a film containing metal, silicon, and oxygen), activation is performed while irradiating near-ultraviolet light toward the Hf-Si film 102. The Hf-Si film 102 is oxidized using the oxygen to form the HfSiO film 103. Since near-ultraviolet light passes through a metal film such as the Hf-Si film 102, the surface layer portion of the Si substrate 101 is excited by near-ultraviolet light. Therefore, in the oxidation step, the oxidation of the surface layer portion of the Si substrate 101 is promoted together with the oxidation of the Hf-Si film 102, and the SiO ₂ film 104 having a sufficiently low interface state is formed. As the activated oxygen, for example, oxygen activated by at least one of plasma excitation, photoexcitation, and ozone supply can be used.

  Thereafter, in a nitriding step (third step of nitriding a film containing metal and oxygen to form a film containing metal, oxygen and nitrogen), nitrogen is introduced into the HfSiO film 103 by plasma nitridation, and the HfSiON film 105 is formed.

Hereinafter, the oxidation process will be described in detail including the configuration of the apparatus used. First, the Si substrate 101 with the Hf-Si film 102 is placed on the substrate support 112 and heated to a required temperature. An oxidizing gas such as O ₂ is introduced into the oxidation treatment chamber 111 through the gas introduction means 113, and the effective exhaust speed of the exhaust means 114 is controlled to maintain the inside of the oxidation treatment chamber 111 at a constant pressure. Near-ultraviolet light emitted from the near-ultraviolet illumination system 118 is irradiated toward the Hf-Si film 102 through the light transmission window 117. By supplying power from the power supply means 116 to the oxidation treatment chamber 111 through the dielectric tube 115, plasma is generated, the oxidizing gas is excited, and activated oxygen is supplied to the vicinity of the substrate. The Hf-Si film 102 is oxidized by the activated oxygen to form a HfSiO film 103 which is a kind of High-k film, and the surface layer portion of the Si substrate 101 is also oxidized, and an SiO ₂ film having a good interface 104 is formed with good controllability.

The wavelength of near ultraviolet light irradiated in the oxidation step is preferably 220 to 380 nm. This near-ultraviolet light is not absorbed by a metal film such as an Hf-Si film or a film containing oxygen and a metal such as an HfSiO film that is being formed, but is mostly absorbed by Si. A silicon oxide film can be efficiently formed on the surface layer portion. Examples of such near-ultraviolet light sources include Kr ₂ excimer lamps, KrF excimer lamps, XeCl excimer lamps, and XeF excimer lamps. These light sources may be used in combination.

  In the present invention, at least one of Hf, Al, La, Zr, Ta, and Y can be used as the metal. In the present invention, the metal film may be a film containing these metals and silicon in addition to the above metal.

In the present invention, as a film containing metal and oxygen constituting the insulating film, the metal silicate film such as the HfSiO film or the ZrSiO film, the HfO ₂ film, the LaO ₂ film, the ZrO ₂ , the HfAlO film, or the LaAlO film. A metal oxide film such as _three films is exemplified. In addition, as a film containing metal, oxygen and nitrogen constituting the insulating film, the above-mentioned metal silicate film such as HfSiON film and ZrSiON film, and further, HfON film, HfAlON film, LaON film, LaAlON film and ZrON film Examples thereof include metal oxynitride films.

FIG. 3 shows the SiO ₂ film thickness (underlying oxide film thickness) in the case where the insulating film formed of the HfSiON film and the SiO ₂ film is formed according to the embodiment of FIG. 1 by using the insulating film forming method according to the present invention. An example of ultraviolet light illumination dependence is shown. This data was obtained as follows.

As the metal film 102 on the Si substrate 101, a film in which an Hf—Si mixed metal having a Si content of 30 atomic% was deposited to a thickness of 0.5 nm by a sputtering method was used. The substrate temperature during the oxidation treatment was controlled at 300 ° C. O ₂ was used as the oxidizing gas and supplied at a flow rate of 1 slm. The pressure inside the oxidation treatment apparatus was maintained at 200 Pa. A XeCl excimer lamp having an emission peak near 308 nm was used as a near-ultraviolet light source. Surface wave interference plasma (SIP) was used for oxygen activation, and neutral oxygen radicals were supplied in the vicinity of the substrate. The oxidation time was fixed at 1 minute. The near-ultraviolet light illuminance was changed in the range of 10 to 100 mW / cm ² .

As a result, the SiO ₂ film thickness tends to be saturated in the high illuminance region, but the underlying SiO ₂ film thickness can be controlled in the range of 0.3 to 0.7 nm by changing the near ultraviolet light illuminance. I understood.

From the above, it becomes possible to form a SiO ₂ film having a good interface on the substrate surface layer portion with a desired controllability by irradiating near ultraviolet light that passes through the metal film in the oxidation step. A high-k insulating film having a low interface state and a low EOT can be formed.

  Hereinafter, the method for forming an insulating film according to the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

[Example 1]
This example was carried out according to the embodiment of FIGS. 1 and 2, and an HfSiON film was formed from an Hf—Si mixed metal film. As the substrate 101, a P-type single crystal Si substrate having a diameter of 200 mm was used.

  First, the surface of the substrate 101 was cleaned by RCA cleaning, and impurities and natural oxide films were removed.

Next, the substrate 101 was transferred into an RF magnetron type sputtering apparatus (not shown). Note that Hf and Si were used as targets for the sputtering apparatus. First, after transporting the substrate 101 into the sputtering apparatus, the sputtering apparatus was evacuated and the pressure was reduced to 5.5 × 10 ⁻⁴ Pa. Further, the substrate 101 was heated by a heating means and held at 300 ° C. Thus, oxygen, moisture, or the like that may oxidize the metal film 102 during the deposition of the metal film 102 was exhausted out of the sputtering apparatus. Subsequently, Ar gas was introduced into the sputtering apparatus at a flow rate of 5 sccm, and the inside of the sputtering apparatus was held at 0.2 Pa. Subsequently, a high frequency voltage was applied to each target to generate plasma, and Hf atoms and Si atoms constituting the target were sputtered. The Hf atoms and Si atoms sputtered on each target flew toward the substrate 101 supported at a position facing the target, and were deposited on the substrate 101. By this treatment, a metal film (Hf-Si film) 102 made of Hf and Si having a thickness of 1 nm was formed. At this time, the composition ratio of Si in the deposited film was about 30 atomic%.

Next, the substrate 101 with the film 102 was transferred into the oxidation treatment chamber 111 of the oxidation apparatus constituting the cluster apparatus, and oxidation treatment was performed. A surface wave excitation plasma was used for oxygen activation. O ₂ gas was introduced through the gas introduction means 113 at a flow rate of 1 slm. Furthermore, the pressure in the oxidation treatment chamber 111 was maintained at 250 Pa. At this time, the temperature of the substrate 101 was maintained at 300 ° C. by a stage that supports the substrate 101 and incorporates a heater capable of heating the substrate 101, that is, the substrate support 112. Near-ultraviolet light from a near-ultraviolet light illumination system 118 using a XeCl excimer lamp was irradiated on the metal film 102 through the light transmission window 117 at an illuminance of 50 mW / cm ² . Thereafter, 2.45 GHz microwaves were radiated from the power supply means 116 including an antenna, and introduced into the oxidation chamber through a dielectric tube 115 that vacuum-isolated the inside and outside of the apparatus to generate surface wave plasma. The HfSiO film 103 was formed by oxidizing the metal film 102 made of Hf and Si on the substrate 101 by the oxygen plasma thus excited. At this time, near-ultraviolet light from the XeCl excimer lamp 118 passes through the Hf-Si film 102 and the HfSiO film 103 being formed, excites Si in the surface layer portion of the underlying substrate 101, and the oxidation thereof is promoted to be good. A SiO ₂ film 104 having a smooth interface was formed.

  Next, in order to nitride the formed HfSiO film 103, the substrate was transferred into a plasma apparatus (not shown) that generates nitrogen plasma by surface wave excitation plasma. The sputtering device and the plasma device are one of modules constituting a cluster device for continuously performing a plurality of processes, and the area for transporting the substrate between the devices was always kept at a high vacuum. For this reason, the substrate was held in an atmosphere in which the co-sputtered Hf and Si were not easily oxidized by oxygen remaining in the apparatus from the co-sputtering process to the nitriding process.

In the plasma apparatus, N ₂ gas was introduced at a flow rate of 200 sccm. The pressure in the plasma apparatus was kept at 30 Pa. At this time, the substrate 101 was held at 200 ° C. by a stage incorporating a heater that supports the substrate 101 and can heat the substrate. Thereafter, 2.45 GHz microwaves were radiated from an antenna (not shown) and introduced into the plasma device via a dielectric (not shown) that isolates the inside and outside of the device to generate surface wave plasma. The HfSiO film 103 was nitrided by the nitrogen plasma thus excited.

When the cross section of the film thus formed was observed by TEM, a thin silicon oxide film 104 having a thickness of about 0.6 nm was formed on the silicon substrate 101, and a HfSiON film 105 having a thickness of 1.6 nm was further formed thereon. It was confirmed that Further, when the nitrogen concentration contained in the Hf silicate film 105 nitrided by XPS was measured, it was confirmed that about 11 atomic% of nitrogen was introduced into the film. When the electrical characteristics were measured, good results with sufficiently low EOT of 1.02 nm and a leakage current density of 2.3E-4 A / cm ² were obtained.

[Example 2]
This example was carried out according to the embodiment of FIGS. 1 and 2, and an HfSiON film was formed from an Hf single metal film. As the substrate 101, a P-type single crystal Si substrate having a diameter of 200 mm was used.

  First, the surface of the substrate 101 was cleaned by RCA cleaning, and impurities and natural oxide films were removed.

Next, the substrate 101 was transferred into an RF magnetron type sputtering apparatus (not shown). Note that only Hf was used as the target of the sputtering apparatus. First, after transporting the substrate 101 into the sputtering apparatus, the sputtering apparatus was evacuated and the pressure was reduced to 3.0 × 10 ⁻⁴ Pa. Further, the substrate 101 was heated by a heating means and held at 300 ° C. Thus, oxygen, moisture, or the like that may oxidize the metal film 102 during the deposition of the metal film 102 was exhausted out of the sputtering apparatus. Subsequently, Ar gas was introduced into the sputtering apparatus at a flow rate of 10 sccm, and the inside of the sputtering apparatus was held at 0.2 Pa. Subsequently, a high frequency voltage was applied to the target to generate plasma, and sputtering of Hf atoms constituting the target was performed. The Hf atoms sputtered on the target flew toward the substrate 101 supported at a position facing the target and deposited on the substrate 101. By this treatment, a metal film (Hf film) 102 made of Hf having a thickness of 0.7 nm was formed.

Next, the substrate 101 with the film 102 was transferred into the oxidation treatment chamber 111 of the oxidation apparatus constituting the cluster apparatus, and oxidation treatment was performed. A surface wave excitation plasma was used for oxygen activation. O ₂ gas was introduced through the gas introduction means 113 at a flow rate of 1 slm. Furthermore, the pressure in the oxidation treatment chamber 111 was maintained at 200 Pa. At this time, the temperature of the substrate 101 was maintained at 450 ° C. by a stage that supports the substrate 101 and incorporates a heater capable of heating the substrate 101, that is, the substrate support 112. Near-ultraviolet light from a near-ultraviolet light illumination system 118 using a XeCl excimer lamp was irradiated on the metal film 102 through the light transmission window 117 at an illuminance of 100 mW / cm ² . Thereafter, 2.45 GHz microwaves were radiated from the power supply means 116 including an antenna, and introduced into the oxidation chamber through a dielectric tube 115 that vacuum-isolated the inside and outside of the apparatus to generate surface wave plasma. The Hf film 102 on the substrate 101 was oxidized by the oxygen plasma thus excited to form the HfSiO film 103. At this time, near-ultraviolet light from the XeCl excimer lamp 118 passes through the Hf film 102 and the HfSiO film 103 that is being formed to excite Si in the surface layer portion of the underlying substrate 101, and its oxidation is promoted to achieve a good interface. A SiO ₂ film 104 having the structure was formed.

  Next, in order to nitride the formed HfSiO film 103, the substrate was transferred into a plasma apparatus (not shown) that generates nitrogen plasma by surface wave excitation plasma. The sputtering device and the plasma device are one of modules constituting a cluster device for continuously performing a plurality of processes, and the area for transporting the substrate between the devices was always kept at a high vacuum. For this reason, the substrate was held in an atmosphere in which the sputtered Hf was difficult to be oxidized by oxygen remaining in the apparatus from the sputtering process to the nitriding process.

In the plasma apparatus, N ₂ gas was introduced at a flow rate of 400 sccm. The pressure in the plasma apparatus was kept at 40 Pa. At this time, the substrate 101 was held at 200 ° C. by a stage incorporating a heater that supports the substrate 101 and can heat the substrate. Thereafter, 2.45 GHz microwaves were radiated from an antenna (not shown) and introduced into the plasma device via a dielectric (not shown) that isolates the inside and outside of the device to generate surface wave plasma. The HfSiO film 103 was nitrided by the nitrogen plasma thus excited.

When the cross section of the film thus formed was observed by TEM, a thin silicon oxide film 104 having a thickness of about 0.6 nm was formed on the silicon substrate 101, and a HfSiON film 105 having a thickness of 1.5 nm was further formed thereon. It was confirmed that Further, when the nitrogen concentration contained in the Hf silicate film 105 nitrided by XPS was measured, it was confirmed that about 9 atomic% of nitrogen was introduced into the film. When the electrical characteristics were measured, good results with sufficiently low EOT of 0.95 nm and leakage current density of 8.1E-4 A / cm ² were obtained.

[Example 3]
This example was performed according to the embodiment of FIGS. 1 and 2, and a LaAlO film was formed from a La—Al mixed metal film. As the substrate 101, a P-type single crystal Si substrate having a diameter of 200 mm was used.

  First, the surface of the substrate 101 was cleaned by RCA cleaning, and impurities and natural oxide films were removed.

Next, the substrate 101 was transferred into an RF magnetron type sputtering apparatus (not shown). Note that La and Al were used as targets of the sputtering apparatus. First, after transporting the substrate 101 into the sputtering apparatus, the sputtering apparatus was evacuated and decompressed to 1.0 × 10 ⁻⁴ Pa. Further, the substrate 101 was heated by a heating means and maintained at 250 ° C. Thus, oxygen, moisture, or the like that may oxidize the metal film 102 during the deposition of the metal film 102 was exhausted out of the sputtering apparatus. Subsequently, Ar gas was introduced into the sputtering apparatus at a flow rate of 10 sccm, and the inside of the sputtering apparatus was held at 0.2 Pa. Subsequently, a high frequency voltage was applied to each target to generate plasma, and La atoms and Al atoms constituting the target were sputtered. La atoms and Al atoms sputtered on each target flew toward the substrate 101 supported at a position facing the target, and were deposited on the substrate 101. By this treatment, a metal film (La—Al film) 102 made of La and Al having a film thickness of 0.8 nm was formed. At this time, the Al composition ratio in the deposited metal film 102 was 35 atomic%.

Next, the substrate 101 with the film 102 was transferred into the oxidation treatment chamber 111 of the oxidation apparatus constituting the cluster apparatus, and oxidation treatment was performed. A surface wave excitation plasma was used for oxygen activation. O ₂ gas was introduced through the gas introduction means 113 at a flow rate of 1 slm. Furthermore, the pressure in the oxidation treatment chamber 111 was maintained at 200 Pa. At this time, the temperature of the substrate 101 was maintained at 300 ° C. by a stage that supports the substrate 101 and incorporates a heater capable of heating the substrate 101, that is, the substrate support 112. Near-ultraviolet light from a near-ultraviolet light illumination system 118 using a Kr ₂ excimer lamp was irradiated on the metal film 102 through the light transmission window 117 at an illuminance of 40 mW / cm ² . Thereafter, 2.45 GHz microwaves were radiated from the power supply means 116 including an antenna, and introduced into the oxidation chamber through a dielectric tube 115 that vacuum-isolated the inside and outside of the apparatus to generate surface wave plasma. The La—Al film 102 on the substrate 101 was oxidized by the oxygen plasma thus excited to form a LaAlO film 103. At this time, near-ultraviolet light from the Kr ₂ excimer lamp 118 is transmitted through the La—Al film 102 and the LaAlO film 103 being formed to excite Si in the surface layer portion of the underlying substrate 101, and its oxidation is promoted. An SiO ₂ film 104 having a good interface was formed.

When the cross section of the film thus formed was observed by TEM, a thin silicon oxide film 104 having a thickness of about 0.5 nm was formed on the silicon substrate 101, and a LaAlO film 103 having a thickness of 1.5 nm was further formed thereon. It was confirmed that When the electrical characteristics were measured, good results with a sufficiently low EOT of 0.87 nm and a leakage current density of 5.5E-2 A / cm ² were obtained.

[Example 4]
This example was carried out according to the embodiment of FIGS. 1 and 2, and a ZrSiO film was formed from a Zr—Si mixed metal film. As the substrate 101, a P-type single crystal Si substrate having a diameter of 200 mm was used.

  First, the surface of the substrate 101 was cleaned by RCA cleaning, and impurities and natural oxide films were removed.

Next, the substrate 101 was transferred into an RF magnetron type sputtering apparatus (not shown). Note that Zr and Si were used as targets for the sputtering apparatus. First, after transporting the substrate 101 into the sputtering apparatus, the sputtering apparatus was evacuated and the pressure was reduced to 2.3 × 10 ⁻⁴ Pa. Further, the substrate 101 was heated by a heating means and held at 300 ° C. Thus, oxygen, moisture, or the like that may oxidize the metal film 102 during the deposition of the metal film 102 was exhausted out of the sputtering apparatus. Subsequently, Ar gas was introduced into the sputtering apparatus at a flow rate of 5 sccm, and the inside of the sputtering apparatus was held at 0.2 Pa. Subsequently, a high frequency voltage was applied to each target to generate plasma, and Zr atoms and Si atoms constituting the target were sputtered. Zr atoms and Si atoms sputtered on each target flew toward the substrate 101 supported at a position facing the target, and were deposited on the substrate 101. By this treatment, a metal film (Zr—Si film) 102 made of Zr and Si having a thickness of 0.7 nm was formed. At this time, the composition ratio of Si in the deposited metal film 102 was 30 atomic%.

Next, the substrate 101 with the film 102 was transferred into the oxidation treatment chamber 111 of the oxidation apparatus constituting the cluster apparatus, and oxidation treatment was performed. A surface wave excitation plasma was used for oxygen activation. O ₂ gas was introduced through the gas introduction means 113 at a flow rate of 1 slm. Furthermore, the pressure in the oxidation treatment chamber 111 was maintained at 250 Pa. At this time, the temperature of the substrate 101 was maintained at 300 ° C. by a stage that supports the substrate 101 and incorporates a heater capable of heating the substrate 101, that is, the substrate support 112. Near-ultraviolet light from a near-ultraviolet light illumination system 118 using a XeCl excimer lamp was irradiated on the metal film 102 through the light transmission window 117 at an illuminance of 50 mW / cm ² . Thereafter, 2.45 GHz microwaves were radiated from the power supply means 116 including an antenna, and introduced into the oxidation chamber through a dielectric tube 115 that vacuum-isolated the inside and outside of the apparatus to generate surface wave plasma. The Zr—Si film 102 on the substrate 101 was oxidized by the oxygen plasma thus excited to form a ZrSiO film 103. At this time, the near-ultraviolet light from the XeCl excimer lamp 118 passes through the Zr—Si film 102 and the ZrSiO film 103 being formed, excites Si in the surface layer portion of the underlying substrate 101, and the oxidation thereof is promoted to be good. A SiO ₂ film 104 having a smooth interface was formed.

When the cross section of the film thus formed was observed by TEM, a thin silicon oxide film 104 having a thickness of about 0.5 nm was formed on the silicon substrate 101, and a ZrSiO film 103 having a thickness of 1.3 nm was further formed thereon. It was confirmed that When the electrical characteristics were measured, good results with a sufficiently low EOT of 0.85 nm and a leakage current density of 4.3E-2 A / cm ² were obtained.

[Example 5]
This example was performed according to the embodiment of FIGS. 1 and 2, and a ZrSiO film was formed from a Zr single metal film. As the substrate 101, a P-type single crystal Si substrate having a diameter of 200 mm was used.

  First, the surface of the substrate 101 was cleaned by RCA cleaning, and impurities and natural oxide films were removed.

Next, the substrate 101 was transferred into an RF magnetron type sputtering apparatus (not shown). Note that only Zr was used as the target of the sputtering apparatus. First, after transporting the substrate 101 into the sputtering apparatus, the sputtering apparatus was evacuated and the pressure was reduced to 2.0 × 10 ⁻⁴ Pa. Further, the substrate 101 was heated by a heating means and held at 300 ° C. Thus, oxygen, moisture, or the like that may oxidize the metal film 102 during the deposition of the metal film 102 was exhausted out of the sputtering apparatus. Subsequently, Ar gas was introduced into the sputtering apparatus at a flow rate of 10 sccm, and the inside of the sputtering apparatus was held at 0.2 Pa. Subsequently, a high frequency voltage was applied to each target to generate plasma, and sputtering of Zr atoms constituting the target was performed. Zr atoms sputtered on the target flew toward the substrate 101 supported at a position facing the target and deposited on the substrate 101. By this treatment, a metal film (Zr film) 102 made of Zr having a thickness of 0.5 nm was formed.

Next, the substrate 101 with the film 102 was transferred into the oxidation treatment chamber 111 of the oxidation apparatus constituting the cluster apparatus, and oxidation treatment was performed. A surface wave excitation plasma was used for oxygen activation. O ₂ gas was introduced through the gas introduction means 113 at a flow rate of 1 slm. Furthermore, the pressure in the oxidation treatment chamber 111 was maintained at 200 Pa. At this time, the temperature of the substrate 101 was maintained at 450 ° C. by a stage that supports the substrate 101 and incorporates a heater capable of heating the substrate 101, that is, the substrate support 112. Near-ultraviolet light from a near-ultraviolet light illumination system 118 using a XeCl excimer lamp was irradiated on the metal film 102 through the light transmission window 117 at an illuminance of 80 mW / cm ² . Thereafter, 2.45 GHz microwaves were radiated from the power supply means 116 including an antenna, and introduced into the oxidation chamber through a dielectric tube 115 that vacuum-isolated the inside and outside of the apparatus to generate surface wave plasma. The Zr film 102 on the substrate 101 was oxidized by the oxygen plasma thus excited to form a ZrSiO film 103. At this time, near-ultraviolet light from the XeCl excimer lamp 118 passes through the Zr film 102 and the ZrSiO film 103 that is being formed, and excites Si in the surface layer portion of the underlying substrate 101, and its oxidation is promoted to achieve a good interface. A SiO ₂ film 104 having the structure was formed.

When the cross section of the film thus formed was observed by TEM, a thin silicon oxide film 104 having a thickness of about 0.6 nm was formed on the silicon substrate 101, and a ZrSiO film 103 having a thickness of 1.3 nm was further formed thereon. It was confirmed that When the electrical characteristics were measured, good results were obtained with a sufficiently low EOT of 0.83 nm and a leakage current density of 7.8E-2 A / cm ² .

It is process sectional drawing for demonstrating one Embodiment of the formation method of the insulating film by this invention. It is typical sectional drawing of the apparatus used for implementation of the formation method of the insulating film by this invention. It is a graph which shows an example of the near-ultraviolet-light illumination dependence of the base oxide film thickness at the time of forming an insulating film using the formation method of the insulating film by this invention. It is process sectional drawing for demonstrating an example of the formation process of the conventional high dielectric constant gate insulating film. It is process sectional drawing for demonstrating the other example of the formation process of the conventional high dielectric constant gate insulating film.

Explanation of symbols

101, 501 Si substrate 102, 502 Metal film 103, 503 Metal silicate film 104, 504 SiO ₂ film 105, 505 Metal nitride silicate film 111 Oxidation chamber 112 Substrate support 113 Gas introduction means 114 Exhaust means 115 Dielectric tube 116 Electric power Supply means 117 Light transmission window 118 Near ultraviolet light illumination system

Claims (9)

A method of forming an insulating film on a silicon substrate,
A first step of forming a metal film on a silicon substrate;
A second step of oxidizing the metal film to form a film containing metal and oxygen,
In the second step, when the metal film is oxidized, the metal film is irradiated with near ultraviolet light to oxidize a surface layer portion of the silicon substrate to form the silicon oxide film. Method for forming a film.   The method according to claim 1, further comprising a third step of nitriding the film containing metal and oxygen formed in the second step to form a film containing metal, oxygen, and nitrogen. A method for forming an insulating film.   3. The method of forming an insulating film according to claim 1, wherein the metal is at least one of Hf, Al, La, Zr, Ta, and Y. 4.   The method for forming an insulating film according to claim 1, wherein the metal film includes silicon in addition to the metal.   The method for forming an insulating film according to claim 1, wherein the wavelength of the near ultraviolet light is 220 to 380 nm. Wherein as a light source of near ultraviolet light, Kr ₂ excimer lamp, which comprises using at least one of KrF excimer lamps, XeCl excimer lamp and XeF excimer lamp, insulation according to any one of claims 1 to 5 Method for forming a film.   The method for forming an insulating film according to claim 1, wherein the metal film is oxidized using activated oxygen in the second step.   8. The method of forming an insulating film according to claim 7, wherein the activated oxygen is activated using at least one of plasma excitation, photoexcitation, and ozone supply.   The method for forming an insulating film according to claim 1, wherein the metal film is formed by sputtering in the first step.