JPH11288933A - Method for forming insulation film and manufacture of p-type semiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the reduction of a current drive capacity due to the infiltration of nitrogen atoms into a channel formation region by forming an insulation film by a first process for heat-treating a semiconductor layer in a nitriding atmosphere, where an atmospheric temperature is determined to be at a specific range and a second process for heat-treating the semiconductor layer in an oxidizing atmosphere. SOLUTION: In a first process, a semiconductor layer 10 is heat-treated (nitriding treatment) in a nitriding atmosphere at an atmospheric temperature of 200-500 deg.C, thus forming an extremely thin nitride film on the surface of the semiconductor layer 10. By heat-treating (oxidation treatment) the semiconductor layer 10 in an oxidizing atmosphere in a second process, the oxidation of the semiconductor layer 10 advances due to the oxidation seed through a nitriding film such as a silicon nitriding film, thus forming an oxide film such as a silicon oxide film on the semiconductor film 10 in the interface between the nitriding film and the semiconductor layer. In this manner, by forming an insulating film 2 in two stages, the amount of nitriding atom contained in the insulation film near the surface of the semiconductor layer can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming an insulating film and a method for manufacturing a p-type semiconductor device using the method for forming an insulating film.

[0002]

2. Description of the Related Art For example, in manufacturing a MOS semiconductor device based on a silicon semiconductor substrate, it is necessary to form a gate insulating film made of, for example, a silicon oxide film on the surface of the silicon semiconductor substrate. In addition, a thin film transistor (TF
In the manufacture of T), it is necessary to form a gate insulating film made of, for example, a silicon oxide film on the surface of the silicon layer provided on the insulating substrate. It is not an exaggeration to say that such a silicon oxide film is responsible for the reliability of the semiconductor device. Therefore, a silicon oxide film is always required to have high dielectric breakdown voltage and long-term reliability. In particular, in a MOS semiconductor device having a design rule of 0.13 μm or less, the thickness of the gate insulating film is required to be 4 nm or less, and such an extremely thin gate insulating film is required to have more excellent characteristics. You.

Recently, in CMOS transistors,
To reduce power consumption, a low power supply voltage has been attempted. For this reason, a p-channel MOS semiconductor device (hereinafter referred to as pM
A sufficiently low and symmetric threshold voltage is required for an n-channel MOS semiconductor device. In order to cope with such a demand, in a pMOS semiconductor device, a gate electrode composed of a polysilicon thin film containing a p-type impurity is replaced with a gate electrode composed of a polysilicon thin film containing an n-type impurity. Is used. However, boron atoms (B), which are commonly used p-type impurities, easily pass through the gate insulating film from the gate electrode to the silicon semiconductor substrate by various heat treatments in a semiconductor device manufacturing process after the formation of the gate electrode. , The threshold voltage of the pMOS semiconductor element is varied. Such a phenomenon appears more remarkably when the gate insulating film is made thinner to reduce the power supply voltage.

A technique of introducing a nitrogen atom into a gate insulating film by nitriding a silicon semiconductor substrate and thereafter performing an oxidation process on the silicon semiconductor substrate has been proposed.
For example, reference 1 "Evaluation of Interfacial Nitrogen
Concentration of RTP Oxynitrides by Reoxidation ",
Y. Okada, et al., J. Electrochem. Soc., Vol. 140,
No. 6, June 1993, ppL87-L89. As a technique for suppressing a phenomenon in which boron atoms (B) pass from the gate electrode through the gate insulating film and reach the silicon semiconductor substrate (referred to as a boron atom penetration phenomenon), nitrogen atoms are contained in the gate insulating film. For example, the technique introduced in Ref. 2 “Evaluation of ultra-thin Si direct nitridation / oxide gate insulating film”, Takayuki Aoyama et al., IEICE Technical Report SDM93-58, 1993-0
7, pp15-22.

Usually, nitrogen atoms are introduced into a gate insulating film by heat-treating a silicon semiconductor substrate in a reactive gas atmosphere in which nitrogen atoms are one of the constituent atoms. Specifically, first, a silicon oxide film is formed on the surface of the silicon semiconductor substrate, and then the silicon oxide film is subjected to a heat treatment in an NH ₃ gas or N ₂ O gas atmosphere. Hereinafter, such a method is referred to as a conventional first method for convenience. Alternatively, in the above document 1, first, in an atmosphere of N ₂ O gas 100% at an atmospheric temperature of 1100 ° C.,
Heat-treating (nitriding) the silicon semiconductor substrate, and then
An oxidation process is performed on the silicon semiconductor substrate for 85 minutes. Hereinafter, such a method is referred to as a second conventional method for convenience. In the above-mentioned document 2, first, for example, 5
% -NH ₃ / Ar (760 torr), nitriding the silicon semiconductor substrate in an atmosphere of 550 ° C. for 10 minutes, and then 10% -O ₂ / Ar (760 torr), 1000 ° C.
Oxidation treatment is performed in the atmosphere of 60 to 90 minutes. Hereinafter, such a method is referred to as a conventional third method for convenience.

[0006]

SUMMARY OF THE INVENTION However, the conventional first
In the gate insulating film obtained by the method of FIG.
As shown by the IMS analysis results, many nitrogen atoms are present in the gate insulating film near the interface between the gate insulating film and the surface of the silicon semiconductor substrate (that is, the interface between the gate insulating film and the channel formation region). In addition, there is a problem that the current driving capability of the pMOS semiconductor element is reduced.

On the other hand, in the gate insulating film obtained by the second conventional method, as shown in FIG. 4 of Document 1, the region of the gate insulating film containing a large amount of nitrogen atoms is located on the silicon semiconductor substrate side. Although it is located closer to the surface of the gate insulating film, the thickness of the gate insulating film is about 20 nm. Therefore, it is difficult to reduce the thickness of the gate insulating film by the second conventional method described in the above-mentioned Document 1. In the conventional gate insulating film obtained by the third method, as shown in FIG. 2 of Reference 2, the interface between the gate insulating film and the surface of the silicon semiconductor substrate (that is, the gate insulating film Since the nitrogen atoms are uniformly contained in the depth direction of the gate insulating film up to the vicinity of the (interface), the current driving capability of the pMOS semiconductor element may be reduced depending on the formation conditions of the gate insulating film.

Accordingly, an object of the present invention is to prevent the penetration of boron atoms without fail, and to provide a p-channel type MO.
It is possible to avoid the occurrence of the problem that the current driving capability of the S semiconductor element is reduced, and to form an insulating film capable of forming an extremely thin insulating film. An object of the present invention is to provide a method for manufacturing a semiconductor device.

[0009]

According to a first aspect of the present invention, there is provided a method for forming an insulating film, comprising:
(A) a first step of heat-treating the semiconductor layer in a nitriding atmosphere at an atmospheric temperature of 200 to 500 ° C .; and (b) a second step of heat-treating the semiconductor layer in an oxidizing atmosphere. And forming an insulating film on the surface of the semiconductor layer.

The first object of the present invention for achieving the above object is as follows.
The method of manufacturing a p-type semiconductor device according to the aspect (A), comprises the steps of: (A) forming a gate insulating film on the surface of the semiconductor layer;
(B) a step of forming a gate electrode made of a semiconductor thin film containing a p-type impurity on the gate insulating film, wherein the step (A) comprises the steps of (a) in a nitriding atmosphere at an ambient temperature of 200 to 500 ° C. A first step of heat-treating the semiconductor layer; and (b) a second step of heat-treating the semiconductor layer in an oxidizing atmosphere.

The second object of the present invention to achieve the above object.
The method for forming an insulating film according to the first aspect includes (a) a first step of irradiating the semiconductor layer with a pulse laser in a nitriding atmosphere and (b) a second step of heat-treating the semiconductor layer in an oxidizing atmosphere. And forming an insulating film on the surface of the semiconductor layer.

The second object of the present invention for achieving the above object is as follows.
The method of manufacturing a p-type semiconductor device according to the aspect (A), comprises the steps of: (A) forming a gate insulating film on the surface of the semiconductor layer;
(B) a step of forming a gate electrode made of a semiconductor thin film containing a p-type impurity on the gate insulating film, and the step (A) is: (a) irradiating the semiconductor layer with a pulse laser in a nitriding atmosphere. The method is characterized by comprising a first step and (b) a second step of heat-treating the semiconductor layer in an oxidizing atmosphere.

According to the first or second embodiment of the present invention, p
In a method of manufacturing a p-type semiconductor element, a semiconductor thin film containing a p-type impurity (for example, a silicon thin film such as a polysilicon thin film or an amorphous silicon thin film or a Si-Ge mixed crystal system)
The gate electrode is formed by, for example, forming a silicon thin film containing a p-type impurity (for example, boron) based on the CVD method, and then patterning the silicon thin film, and forming a silicon thin film containing no impurity by the CVD method. After the formation, a p-type impurity (for example, boron or BF ₂ ) is implanted into the silicon thin film by an ion implantation method, and then the silicon thin film is patterned. The silicon thin film containing no impurity is formed by the CVD method and then patterned. Then, a method of implanting a p-type impurity (for example, boron or BF ₂ ) into the silicon thin film by an ion implantation method can be mentioned. In the step (B), after forming a semiconductor thin film made of a silicon thin film containing a p-type impurity, a silicide layer is formed on the semiconductor thin film, and then the silicide layer and the semiconductor thin film are patterned to form a polycide structure. May be formed. Alternatively, after forming a semiconductor thin film made of a silicon thin film containing a p-type impurity, a high melting point metal layer such as tungsten is formed on the semiconductor thin film, and then the high melting point metal layer and the semiconductor thin film are patterned. A gate electrode having a two-layer structure of a refractory metal layer and a semiconductor thin film may be formed. Further, a so-called offset oxide film may be formed on the semiconductor thin film, the silicide layer, and the high melting point metal layer.

The method for forming an insulating film according to the first or second aspect of the present invention or the method for manufacturing a p-type semiconductor device according to the first or second aspect (hereinafter, these are collectively referred to as
The nitriding atmosphere in (may be referred to as the present invention) is N 2
An H ₃ gas atmosphere, a NO gas atmosphere, or an N ₂ O gas atmosphere is preferable, and an NH ₃ gas atmosphere is particularly preferable. The nitriding atmosphere may be a mixed gas atmosphere of these gases and an inert gas such as N ₂ or Ar, or the nitriding atmosphere may be a reduced pressure atmosphere. Thereby, a thinner nitride film (for example,
(Silicon nitride film) can be formed with good film thickness controllability.

In the method for forming an insulating film according to the first aspect of the present invention or the method for manufacturing a p-type semiconductor device according to the first aspect, the heat treatment in the first step may be performed based on a furnace heat treatment method. However, from the viewpoint of forming an ultra-thin nitride film on the surface of the semiconductor layer, the rapid heat treatment method (Ra
It is desirable to carry out based on pid Thermal Processing). The temperature of the heat treatment (the temperature of the semiconductor layer) in the first step is 200 ° C. to 500 ° C. When the heat treatment in the first step is performed based on the rapid heat treatment method, the heat treatment time after reaching the heat treatment temperature is 0.1 second to 10 seconds.
Seconds are desirable from the viewpoint of forming an extremely thin nitride film with good film thickness controllability. If the heat treatment temperature in the first step is lower than 200 ° C., it may be difficult to nitride the surface of the semiconductor layer. On the other hand, when the heat treatment temperature exceeds 500 ° C., the thickness of the nitride film formed on the surface of the semiconductor layer becomes too large, and it is difficult to form an oxide film on the semiconductor layer with good film thickness controllability in the second step. Alternatively, it may be difficult to form an extremely thin insulating film or gate insulating film (hereinafter, these may be collectively referred to as an insulating film or the like).

In the method for forming an insulating film according to the second aspect of the present invention or the method for manufacturing a p-type semiconductor device according to the second aspect, the pulse laser for irradiating the semiconductor layer raises the semiconductor layer in a very short time. Any pulse laser capable of heating and nitriding the surface of the semiconductor layer may be used. For example, an excimer laser can be used. The laser wavelength range is 20 nm to 500 nm, the irradiation energy density is 0.1 to 1 J / cm ² , and the irradiation time is 0.1 to 1 J / cm ² .
01 to 0.1 nsec.

Further, the MO based on the silicon semiconductor substrate is
Conventionally, when manufacturing an S semiconductor device, before forming a gate insulating film, it is washed with an aqueous solution of NH ₄ OH / H ₂ O ₂ ,
The surface of the silicon semiconductor substrate is cleaned by RCA cleaning in which the substrate is cleaned with an aqueous solution of Cl / H ₂ O ₂ to remove fine particles and metal impurities from the surface. By the way, when the RCA cleaning is performed, the surface of the silicon semiconductor substrate reacts with the cleaning liquid to form a silicon oxide film having a thickness of about 0.5 to 1 nm.
The thickness of such a silicon oxide film is not uniform, and
The cleaning liquid component remains in the silicon oxide film. Therefore, the silicon semiconductor substrate is immersed in a hydrofluoric acid aqueous solution to remove the silicon oxide film, and further, the chemical component is removed with pure water. Thereby, it is possible to obtain a surface of the silicon semiconductor substrate that is mostly terminated with hydrogen and extremely partially terminated with fluorine. In this specification, obtaining a surface of a silicon semiconductor substrate that is mostly terminated with hydrogen and a very small portion is terminated with fluorine is referred to as exposing the surface of the silicon semiconductor substrate in this specification. I do. Thereafter, an insulating film or the like is formed on the surface of the silicon semiconductor substrate. By the way, if the atmosphere before forming the insulating film or the like is a high-temperature non-oxidizing atmosphere, the surface of the silicon semiconductor substrate becomes rough (unevenness). Such a phenomenon occurs because a part of the Si—H bond or a part of the Si—F bond formed on the surface of the silicon semiconductor substrate by washing with the hydrofluoric acid aqueous solution and pure water increases hydrogen or fluorine. It is thought to be lost due to thermal desorption and caused by an etching phenomenon occurring on the surface of the silicon semiconductor substrate. For example, a silicon semiconductor substrate is heated to 600 ° C. in argon gas.
The occurrence of severe irregularities on the surface of a silicon semiconductor substrate when the temperature is raised as described above is described in “Ultra Clean ULSI Technology”, page 21 by Tadahiro Omi, published by Baifukan.
In the method for forming an insulating film according to the first aspect of the present invention or the method for manufacturing a p-type semiconductor device according to the first aspect, the semiconductor layer is formed in a nitriding atmosphere at an ambient temperature of 200 to 500 ° C. in the first step. Since the heat treatment is performed, the occurrence of such a phenomenon that the surface of such a semiconductor layer (eg, a silicon semiconductor substrate) is roughened (irregularities) can be reliably avoided.

In the present invention, the thickness of the nitride film formed in the first step is 0.5 nm to 2.0 nm, preferably 0.5 nm to 1.5 nm, more preferably 0.5 nm to 1.5 nm.
A thickness of 1.0 nm is desirable from the viewpoint of forming an extremely thin insulating film or the like. The thickness of the nitride film can be measured by, for example, secondary ion mass spectrometry (SIMS). Here, the thickness of the nitride film refers to a half width at a portion of a measurement curve including a peak of a composition (for example, a silicon nitride film or SiN) constituting the nitride film in an analysis result obtained by the SIMS method. It means the deeper of the depths from the surface of the insulating film or the like at that time.

In the present invention, the oxidizing atmosphere can be a dry oxygen gas atmosphere or a wet gas atmosphere. However, when the oxidizing atmosphere is a wet gas atmosphere, the first oxidizing atmosphere depends on the heat treatment conditions in the second step. Bonding of atoms constituting the semiconductor layer formed in the step with nitrogen atoms (for example, Si-
Since the effect of cutting N bonds in the second step is increased, it is desirable to use a dry oxygen gas atmosphere.
The oxidizing atmosphere may be a 100% oxygen gas atmosphere or an oxygen gas atmosphere diluted with an inert gas such as N ₂ or Ar. The second step may be performed based on a furnace heat treatment method or a rapid heat treatment method.
The heat treatment conditions in the second step may be determined depending on the finally required thickness of the insulating film or the like. When the second step is performed based on the furnace heat treatment method, the heat treatment temperature (the temperature of the semiconductor layer) is 800 ° C. to 1000 ° C., and the heat treatment time after reaching the heat treatment temperature is 1 minute to 10 minutes.
Minutes can be illustrated. On the other hand, when the heat treatment is performed based on the rapid heat treatment method, the heat treatment temperature (the temperature of the semiconductor layer) is 900 ° C. to 1100 ° C., and the heat treatment time after reaching the heat treatment temperature is 10 seconds to 5 minutes. Can be.

Usually, before an insulating film or the like is formed on the surface of the silicon semiconductor substrate, the silicon semiconductor substrate is washed by an aqueous solution of NH ₄ OH / H ₂ O ₂ and further washed by an aqueous solution of HCl / H ₂ O ₂ by RCA cleaning. Is cleaned to remove fine particles and metal impurities from the surface, and then the silicon semiconductor substrate is cleaned with a hydrofluoric acid aqueous solution and pure water. However, after that, when the silicon semiconductor substrate is exposed to the air, the surface of the silicon semiconductor substrate is contaminated, moisture and organic substances adhere to the surface of the silicon semiconductor substrate, or
There is a possibility that Si atoms on the surface of the silicon semiconductor substrate may be bonded to a hydroxyl group (OH) (for example, see "Highly-reliable Ga"
te Oxide Formation for Giga-Scale LSIs by using Cl
osed Wet Cleaning System and Wet Oxidation with Ul
tra-DryUnloading ", J. Yugami, et al., Internationala
l Electron Device Meeting Technical Digest 95, pp
855-858). In such a case, if the formation of the insulating film or the like is started as it is, moisture or an organic substance, or, for example, Si-OH is taken into the formed insulating film, and the characteristics of the formed insulating film or the like are deteriorated. It can cause the generation of defective portions. Note that a defect portion is a portion of an insulating film or the like containing a defect such as a silicon dangling bond (Si.) Or a Si-H bond, or a Si-O-
Si bond is compressed by stress or Si-OS
Si-O in which the angle of the i-bond is thick or different from the angle of the Si-O-Si bond in the bulk silicon oxide film
-Means a portion such as an insulating film containing a Si bond. Therefore, in order to avoid the occurrence of such a problem, a step of cleaning the surface of the semiconductor layer before forming the insulating film or the like is included, and the semiconductor layer after the surface cleaning is not exposed to the atmosphere (that is, for example, The atmosphere from the cleaning of the surface of the semiconductor layer to the start of the step of forming the insulating film or the like is an inert gas atmosphere or a vacuum atmosphere), and the formation of the insulating film or the like is preferably performed. Thereby, for example, when a silicon semiconductor substrate is used as a semiconductor layer, an insulating film or the like can be formed on the surface of a silicon semiconductor substrate having a surface that is mostly terminated with hydrogen and a portion of which is extremely terminated with fluorine, Deterioration of the characteristics of the formed insulating film or the like or occurrence of a defective portion can be prevented.

As the semiconductor layer, not only a silicon semiconductor substrate such as a silicon single crystal wafer, but also an epitaxial silicon layer, a polysilicon layer, or an amorphous silicon layer formed on the semiconductor substrate, and further, a silicon semiconductor substrate or any of these layers Means a material layer on which an insulating film is to be formed, such as a semiconductor element formed on a substrate, a Si-Ge mixed crystal, or the like. Forming an insulating film on a semiconductor layer includes not only forming an insulating film on a semiconductor layer formed on or above a semiconductor substrate or the like, but also forming an insulating film on the surface of a semiconductor substrate. The silicon single crystal wafer is CZ
The wafer may be a wafer manufactured by any method such as the MCZ method, the MCZ method, the DLCZ method, and the FZ method, or may have been subjected to hydrogen annealing in advance.

The method of forming an insulating film according to the present invention is, for example, an MO method.
The present invention can be applied to formation of an insulating film in various semiconductor devices, such as formation of a gate insulating film of an S transistor, formation of a gate insulating film of a top gate or bottom gate thin film transistor, formation of a tunnel insulating film of a flash memory, and the like.

In the present invention, when the first step is completed, a nitride film is formed on the surface of the semiconductor layer. Then, in the method for forming an insulating film according to the first aspect of the present invention or the method for manufacturing a p-type semiconductor element according to the first aspect, in the first step, the ambient temperature is 200 to 500.
Heat treatment of semiconductor layer in nitriding atmosphere of ゜ C (nitriding)
Therefore, in the method for forming an insulating film according to the second aspect of the present invention or the method for manufacturing a p-type semiconductor device according to the second aspect, the semiconductor layer is irradiated with a pulse laser in a nitriding atmosphere. Since the nitriding treatment is performed, an extremely thin nitride film can be formed on the surface of the semiconductor layer. Thereafter, in a second step, the semiconductor layer is subjected to heat treatment (oxidation treatment) in an oxidizing atmosphere, whereby oxidation of the semiconductor layer proceeds by oxidizing species penetrating the nitride film (for example, a silicon nitride film), and the nitride film and the semiconductor An oxide film (for example, a silicon oxide film) is formed on the semiconductor layer at the interface between the layers. That is,
Macroscopically, an oxide film and a nitride film are formed on the surface of the semiconductor layer from below. Further, a part of the nitride film contains oxynitride. For example, a part of the silicon nitride film includes silicon nitride oxide (SiON). As described above, by forming the insulating film and the like in two stages, the region of the insulating film and the like containing a large amount of nitrogen atoms is formed near the surface of the insulating film and the like. The amount of nitrogen atoms contained in the insulating film or the like can be reduced.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings based on embodiments of the invention (hereinafter abbreviated as embodiments).

Embodiment 1 Embodiment 1 relates to a method for forming an insulating film and a method for manufacturing a p-type semiconductor device according to the first aspect of the present invention. In the first embodiment, a silicon semiconductor substrate is used as a semiconductor layer. The first step is performed in an NH ₃ gas 100% atmosphere. A method for forming an insulating film and a method for manufacturing a p-type semiconductor device according to the first embodiment will be described below with reference to FIGS. 1 and 2 which are schematic partial cross-sectional views of a silicon semiconductor substrate and the like.

[Step-100] First, an n-type silicon wafer of 8 inches in diameter doped with phosphorus (prepared by CZ method)
LOC is formed on the silicon semiconductor substrate 10 which is
An element isolation region 11 having an OS structure is formed, and then well ion implantation, channel stop ion implantation, and threshold adjustment ion implantation are performed. Note that the element isolation region may have a trench structure or a combination of a LOCOS structure and a trench structure. Thereafter, fine particles and metal impurities on the surface of the silicon semiconductor substrate 10 are removed by RCA cleaning, and then the surface of the silicon semiconductor substrate 10 is cleaned with a 0.1% aqueous hydrofluoric acid solution and pure water. The surface is exposed (see FIG. 1A). The surface of the silicon semiconductor substrate 10 is mostly terminated with hydrogen, and a very small part is terminated with fluorine.

[Step-110] Next, the silicon semiconductor substrate 10 is carried into a rapid thermal processing apparatus (not shown), and the first step of nitriding is performed under the conditions shown in Table 1 below. A nitride film is formed (see FIG. 1B).

[0028]

Table 1 NH ₃ flow rate: 2 SLM Ambient temperature: 400 ° C. Atmospheric pressure: 1.01 × 10 ⁵ Pa (1 atm) Heat treatment time: 1 second

[Step-120] Then, in the same rapid thermal processing apparatus, an oxidation treatment as a second step is performed under the conditions exemplified in Table 2 below. The oxygen atom, which is an oxidizing species,
After reaching the semiconductor layer (silicon semiconductor substrate 10) through the silicon nitride film formed in [Step-110], SiO ₂ is formed by reacting with silicon atoms forming the semiconductor layer. Thus, as shown in FIG. 1C, the gate insulating film 12 can be formed on the surface of the silicon semiconductor substrate 10 corresponding to the semiconductor layer. Here, the total thickness of the insulating film was set to about 4 nm. The insulating film 12 is macroscopically formed of a two-layer structure of a silicon oxide film and a silicon nitride film (the silicon nitride film is an upper layer) formed on the surface of the semiconductor layer (the silicon semiconductor substrate 10). Although the film contains silicon oxynitride, it is represented by one layer in the figure.

[0030]

[Table 2] Dry oxygen flow rate: 2 SLM Ambient temperature: 1000 ° C. Atmospheric pressure: 1.01 × 10 ⁵ Pa (1 atm) Heat treatment time: 60 seconds

[Step-130] Thereafter, the silicon semiconductor substrate 10 corresponding to the semiconductor layer is unloaded from the rapid thermal processing apparatus, and then the silicon semiconductor substrate 1 is transferred to a known CVD apparatus.
Bring in 0. Then, a semiconductor thin film made of a silicon thin film containing no impurities on the entire surface (a polysilicon thin film in the first embodiment) is formed by a CVD method. Next, the semiconductor thin film is patterned based on a photolithography technique and a dry etching technique. Then, boron ions are implanted into the semiconductor thin film and the silicon semiconductor substrate by an ion implantation method. Thereby, the gate insulating film 12
A gate electrode 13 made of a semiconductor thin film (specifically, a polysilicon thin film) containing a p-type impurity can be formed thereon, and at the same time, an LDD structure can be formed (FIG. 2).
(A)).

[Step-140] Next, an insulating layer is formed on the entire surface, and the insulating layer is etched by an anisotropic dry etching technique to form sidewalls 14 on the side walls of the gate electrode 13. Next, in order to form the source / drain regions 15, boron ions are implanted into the silicon semiconductor substrate by an ion implantation method, and then activation heat treatment of the ion-implanted impurities is performed. Thereafter, an interlayer insulating layer 16 is formed on the entire surface.
Is formed by a CVD method, an opening is provided in the interlayer insulating layer 16 above the source / drain region 15, and a wiring material layer is formed on the interlayer insulating layer 16 including the inside of the opening by a sputtering method. By forming a wiring 17 by patterning the wiring material layer, a p-type semiconductor element whose schematic partial cross-sectional view is shown in FIG. 2B can be obtained.

The SI of the insulating film formed in the first embodiment
FIG. 3 shows the results of the MS analysis. As is clear from FIG.
In the analysis result obtained by the SIMS method, the depth from the surface of the insulating film or the like to the peak of the measurement curve of SiN is about 0.5 nm, and an extremely thin silicon nitride film is formed. The total thickness of the insulating film is about 4 nm, and the insulating film near the interface with the silicon semiconductor substrate, which is a semiconductor layer, contains almost no nitrogen atoms.

(Embodiment 2) In Embodiment 2, the conditions of the nitriding treatment as the first step are the conditions shown in Table 3 below. That is, in the second embodiment, the first
Is an NH ₃ atmosphere diluted with a nitrogen gas. Alternatively, as exemplified in Table 4, the atmosphere in the first step can be a reduced-pressure NH ₃ atmosphere. Except for these points, the formation of the insulating film and the like in Embodiment 2 can be the same as that described in Embodiment 1.

[0035]

Table 3 NH ₃ flow rate: 0.2 SLM N ₂ flow rate: 1.8 SLM Atmospheric pressure: 1.01 × 10 ⁵ Pa (1 atm) Atmospheric temperature: 450 ° C. Heat treatment time: 1 second

[0036]

[Table 4] NH ₃ flow rate: 2 SLM Ambient temperature: 450 ° C. Atmospheric pressure: 1.0 × 10 ⁴ Pa Heat treatment time: 1 second

Embodiment 3 Embodiment 3 relates to a method for forming an insulating film and a method for manufacturing a p-type semiconductor device according to the second aspect of the present invention. Also in the third embodiment, a silicon semiconductor substrate is used as a semiconductor layer. The first step is performed in an NH ₃ gas 100% atmosphere.

FIG. 4 is a conceptual diagram of a laser irradiation apparatus. This laser irradiation device includes an excimer laser oscillation device 20,
Attenuator 21, beam homogenizer 22, reaction chamber 23, and XY table 2 provided in reaction chamber 23
4. A laser beam emitted from the excimer laser oscillation device 20 passes through an attenuator 21, is reflected by a mirror, passes through a beam homogenizer 22, and has a desired laser beam energy density and is uniformed within 5%. Formed into a beam. This laser beam passes through a quartz window 25 provided in the upper part of the reaction chamber 23 and enters the silicon semiconductor substrate 10 placed on the XY table 24. In the reaction chamber 23,
A gate valve 26 is provided for loading and unloading the silicon semiconductor substrate 10. In addition, a pipe 27A for introducing NH ₃ gas and a purge gas (N ₂ gas) are provided in the reaction chamber 23 in order to make the atmosphere of the reaction chamber 23 a nitriding atmosphere.
Is introduced. The gas in the reaction chamber 23 is exhausted from the exhaust unit 28 to the outside of the system.

A method of forming an insulating film and a method of manufacturing a p-type semiconductor device according to the third embodiment will be described below with reference again to FIGS. 1 and 2 which are schematic partial sectional views of a silicon semiconductor substrate and the like. I do.

[Step-300] First, as in [Step-100] of the first embodiment, the silicon semiconductor substrate 1
At 0, an element isolation region 11 is formed by a known method, and then well ion implantation, channel stop ion implantation, and threshold adjustment ion implantation are performed. Thereafter, fine particles and metal impurities on the surface of the silicon semiconductor substrate 10 are removed by RCA cleaning, and then the surface of the silicon semiconductor substrate 10 is cleaned with a 0.1% aqueous hydrofluoric acid solution and pure water. The surface is exposed (see FIG. 1A). The surface of the silicon semiconductor substrate 10 is mostly terminated with hydrogen, and a very small part is terminated with fluorine.

[Step-310] Next, the silicon semiconductor substrate 10 is loaded into a laser irradiation apparatus whose conceptual diagram is shown in FIG. (Refer to FIG. 1B). Note that the thickness of the silicon nitride film is 0.5 nm.
And

[0042]

Table 5 NH ₃ flow rate: 2 SLM Atmospheric pressure: 1.3 × 10 ³ Pa Laser used: XeCl excimer laser (308
nm) Laser pulse width: 44 nanoseconds Laser beam energy density: 600 mJ / cm ² Beam size: 20 mm × 20 mm

[Step-320] Thereafter, the silicon semiconductor substrate 10 is unloaded from the laser irradiation apparatus and loaded into the rapid thermal processing apparatus. Then, the oxidation process, which is the second process, is performed under the same conditions as those illustrated in Table 2. Oxygen atoms, which are oxidizing species, pass through the silicon nitride film formed in [Step-310], reach the semiconductor layer (silicon semiconductor substrate 10), react with silicon atoms forming the semiconductor layer, and react with sulfur atoms.
iO ₂ is formed. Thus, as shown in FIG. 1C, the gate insulating film 12 can be formed on the surface of the silicon semiconductor substrate 10 corresponding to the semiconductor layer. Here, the total thickness of the insulating film was set to about 3 nm.

[Step-330] Thereafter, the silicon semiconductor substrate 10 corresponding to the semiconductor layer is unloaded from the rapid thermal processing apparatus, and then [Step-130] and [Step-140] of the first embodiment are executed. , A p-type semiconductor element can be obtained.

As described above, the present invention has been described based on the preferred embodiments, but the present invention is not limited to these embodiments. The various conditions described in the embodiments are merely examples, and can be changed as appropriate.

In the embodiment, the insulating film is formed exclusively on the surface of the silicon semiconductor substrate. However, based on the insulating film forming method of the present invention, the insulating film is formed on the epitaxial silicon layer formed on the substrate. Alternatively, an insulating film can be formed on a surface of a polysilicon layer or an amorphous silicon layer formed on an insulating layer formed on a substrate. Alternatively, an insulating film may be formed on a surface of a silicon layer in the SOI structure, or an insulating film may be formed on a surface of a semiconductor element or a substrate on which components of the semiconductor element are formed, or a surface of a silicon layer formed thereon. May be formed. Further, an insulating film may be formed on a surface of a substrate on which a semiconductor element or a component of the semiconductor element is formed, or a silicon layer formed on a base insulating layer formed thereon. In addition, the method for forming an insulating film of the present invention can be applied to a Si—Ge mixed crystal system.

Alternatively, in the embodiment, 0.1%
After cleaning the surface of the silicon semiconductor substrate constituting the semiconductor layer with a hydrofluoric acid aqueous solution and pure water, the silicon semiconductor substrate constituting the semiconductor layer was carried into a reaction chamber of a rapid heat treatment apparatus or a laser irradiation apparatus. The atmosphere from the surface cleaning of the layer to the loading of the rapid heat treatment apparatus or the laser irradiation into the reaction chamber is controlled by an inert gas (eg, nitrogen gas).
The atmosphere may be good. Note that such an atmosphere may be, for example, an atmosphere of a semiconductor layer surface cleaning apparatus set to an inert gas atmosphere, and a semiconductor layer (for example, a silicon semiconductor substrate) placed in a transport box filled with an inert gas. Using a rapid heat treatment apparatus or a method of carrying into a reaction chamber of laser irradiation, or using a surface cleaning apparatus such as a rapid heat treatment apparatus, a transfer path, a loader and an unloader as shown in FIG. The method can be achieved by a method in which the surface cleaning device is connected to the rapid heat treatment device by a transfer path, and the atmosphere in the surface cleaning device, the transfer path, and the processing chamber of the rapid heat treatment device is set to an inert gas atmosphere.

Alternatively, instead of cleaning the surface of the silicon semiconductor substrate constituting the semiconductor layer with a 0.1% aqueous hydrofluoric acid solution and pure water, the conditions illustrated in Table 6 are used.
The surface of the silicon semiconductor substrate forming the semiconductor layer may be cleaned by a gas phase cleaning method using anhydrous hydrogen fluoride gas. Note that methanol is added to prevent generation of particles. Alternatively, the surface of the silicon semiconductor substrate forming the semiconductor layer may be cleaned by a vapor phase cleaning method using hydrogen chloride gas under the conditions shown in Table 7.
Note that the atmosphere in the surface cleaning apparatus and the atmosphere in the transfer path before starting the surface cleaning of the semiconductor layer or after the surface cleaning is completed may be an inert gas atmosphere, for example, 1.3 ×.
A vacuum atmosphere of about 10 ^-1 Pa (10 ^-3 Torr) may be used. In the case where the atmosphere in the transfer path or the like is a vacuum atmosphere, the atmosphere in the rapid heat treatment apparatus for loading the semiconductor layer or the reaction chamber for laser irradiation is, for example, 1.3 × 10 ⁻¹ Pa.
(10 ⁻³ Torr) vacuum atmosphere. After the completion of the loading of the semiconductor layer, the atmosphere of the reaction chamber of the rapid thermal processing apparatus or the laser irradiation apparatus is temporarily set to an inert gas (for example, nitrogen gas) atmosphere as necessary. After that, the first step may be performed.

[0049]

[Table 6] Anhydrous hydrogen fluoride gas: 300 SCCM Methanol vapor: 80 SCCM Nitrogen gas: 1000 SCCM Pressure: 0.3 Pa Temperature: 60 ° C

[0050]

[Table 7] Hydrogen chloride gas / nitrogen gas: 1% by volume Temperature: 800 ° C

By employing these methods, it is possible to keep the surface of the semiconductor layer free from contamination and the like before forming the insulating film. It is possible to effectively prevent the characteristics of the formed insulating film from being taken down by Si-OH and causing a defective portion to be generated.

The method of forming an insulating film according to the present invention or p.
In the method for manufacturing a semiconductor device, after the completion of the second step of heat-treating the semiconductor layer in an oxidizing atmosphere, the formed insulating film may be subjected to heat treatment. In this case, it is desirable that the atmosphere of the heat treatment be an inert gas atmosphere containing a halogen element. By heat-treating, for example, a silicon oxide film in an inert gas atmosphere containing a halogen element, a silicon oxide film having excellent time-zero dielectric breakdown (TZDB) characteristics and temporal dielectric breakdown (TDDB) characteristics can be obtained. Examples of the inert gas in the heat treatment include a nitrogen gas, an argon gas, and a helium gas. In addition, examples of the halogen element include chlorine, bromine, and fluorine, and among them, chlorine is preferable. Examples of the form of the halogen element contained in the inert gas include hydrogen chloride (HCl), CCl ₄ , C ₂
HCl ₃ , Cl ₂ , HBr and NF ₃ can be mentioned. The content of the halogen element in the inert gas is 0.001 to 10% by volume, based on the form of the molecule or compound,
Preferably it is 0.005 to 10% by volume, more preferably 0.02 to 10% by volume. For example, when using hydrogen chloride gas, the hydrogen chloride gas content in the inert gas is 0.0
It is desirably 2 to 10% by volume. Although the heat treatment may be a single-wafer treatment, it is preferably a furnace annealing treatment. The ambient temperature of the heat treatment is 700 to 1200
C, preferably 700-1000C, more preferably 700-950C. When the heat treatment is furnace annealing, the heat treatment time is 5 to 60 minutes, preferably 10 to 40 minutes, and more preferably 20 to 30 minutes. On the other hand, when the heat treatment is a single-wafer treatment, the heat treatment time is preferably 1 to 10 minutes.

[0053]

According to the present invention, the semiconductor layer is heat-treated in a nitriding atmosphere at an ambient temperature of 200 to 500 ° C. in the first step, or the semiconductor layer is irradiated with a pulse laser in the nitriding atmosphere. Therefore, an extremely thin nitride film (for example, a silicon nitride film) can be formed on the surface of the semiconductor layer. Further, since the formation of the insulating film and the like is performed in two stages, the region of the insulating film and the like containing a large amount of nitrogen atoms is formed near the surface of the insulating film and the like, while the region of the insulating film near the surface of the semiconductor layer which is a channel formation region And the like can reduce the amount of nitrogen atoms contained in them. As a result, unlike the related art, there is no adverse effect on semiconductor element characteristics such as a decrease in current driving capability due to nitrogen atoms penetrating a silicon semiconductor substrate (channel formation region). Further, since nitrogen atoms are contained in the surface region of the insulating film, for example, boron atoms reach the silicon semiconductor substrate through the gate insulating film by various heat treatments in a semiconductor device manufacturing process after formation of the gate electrode, The phenomenon that the threshold voltage of the p-channel MOS semiconductor element fluctuates can be reliably avoided.

[Brief description of the drawings]

FIG. 1 is a schematic partial cross-sectional view of a silicon semiconductor substrate and the like for describing a method for forming an insulating film and a method for manufacturing a p-type semiconductor device according to the present invention.

FIG. 2 is a schematic partial cross-sectional view of a silicon semiconductor substrate and the like for illustrating the method for manufacturing a p-type semiconductor device of the present invention, following FIG.

FIG. 3 shows the SI of the insulating film obtained in the first embodiment of the invention;
It is a graph which shows MS analysis result.

FIG. 4 is a conceptual diagram of a laser irradiation device.

FIG. 5 is a conceptual diagram of a cluster tool device including a surface cleaning device, a rapid heat treatment device, a transfer path, a loader, and an unloader.

FIG. 6 shows SIMS of an insulating film obtained based on a conventional method.
It is a graph which shows an analysis result.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Silicon semiconductor substrate, 11 ... Element isolation region, 12 ... Insulating film (gate insulating film), 13 ... Gate electrode, 14 ... Side wall, 15 ... Source / drain region , 16 ... interlayer insulating layer, 17 ...
Wiring, 20 ... Excimer laser oscillation device, 21 ...
Attenuator, 22 ... Beam homogenizer, 23
..Reaction chamber, 24 XY table, 25 windows made of quartz, 26 gate valves, 27A and 27B
..Piping, 28 ... Exhaust part

Claims (14)

[Claims] 1. A first step of heat-treating a semiconductor layer in a nitriding atmosphere at an ambient temperature of 200 to 500 ° C., and (b) a second step of heat-treating the semiconductor layer in an oxidizing atmosphere. A method for forming an insulating film, comprising: forming an insulating film on a surface of a semiconductor layer. 2. The method according to claim 1, wherein the nitriding atmosphere is an NH ₃ gas atmosphere. 3. The method according to claim 1, wherein the oxidizing atmosphere is a dry oxygen gas atmosphere. 4. The method according to claim 1, wherein the heat treatment in the first step is based on a rapid heat treatment method. 5. A step of forming a gate insulating film on a surface of a semiconductor layer, and a step of forming a gate electrode made of a semiconductor thin film containing a p-type impurity on the gate insulating film. a method for manufacturing a p-type semiconductor device, wherein the step (A) comprises: (a) a first step of heat-treating the semiconductor layer in a nitriding atmosphere at an ambient temperature of 200 to 500 ° C .; A second step of heat-treating the semiconductor layer in a neutral atmosphere. 6. The method according to claim 5, wherein the nitriding atmosphere is an NH ₃ gas atmosphere. 7. The method as claimed in claim 5, wherein the oxidizing atmosphere is a dry oxygen gas atmosphere. 8. The method according to claim 5, wherein the heat treatment in the first step is based on a rapid heat treatment method. 9. A first step of irradiating the semiconductor layer with a pulsed laser in a nitriding atmosphere, and (b) a second step of heat treating the semiconductor layer in an oxidizing atmosphere. A method for forming an insulating film, comprising forming an insulating film on a surface of a semiconductor layer. 10. The method according to claim 9, wherein the nitriding atmosphere is an NH ₃ gas atmosphere. 11. The method according to claim 9, wherein the oxidizing atmosphere is a dry oxygen gas atmosphere. 12. A step of forming a gate insulating film on the surface of a semiconductor layer, and a step of forming a gate electrode made of a semiconductor thin film containing a p-type impurity on the gate insulating film. a method for manufacturing a p-type semiconductor device, wherein the step (A) comprises: (a) a first step of irradiating a semiconductor layer with a pulsed laser in a nitriding atmosphere; 2. A method of manufacturing a p-type semiconductor device, comprising: a second step of heat-treating a semiconductor layer. 13. The method according to claim 12, wherein the nitriding atmosphere is an NH ₃ gas atmosphere. 14. The method according to claim 12, wherein the oxidizing atmosphere is a dry oxygen gas atmosphere.