JP2010028008A - Method for manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing semiconductor devices by which high-reliability semiconductor devices can be manufactured. <P>SOLUTION: The method for manufacturing a semiconductor device 1 includes a process for forming a silicon oxide film 12 on a substrate 11, a process for forming a silicon oxide-nitride film 13 by introducing nitrogen into the silicon oxide film 12 and a process for forming an insulating film 14 which includes at least one of Zr and Hf on the silicon oxide-nitride film 13. In the process for forming the silicon oxide film 12 on the substrate 11, after forming the silicon oxide film 12 on the substrate 11, the silicon oxide film 12 is heat-treated at 1,050&deg;C or more but not exceeding 1,100&deg;C. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device.

In recent years, miniaturization and high integration of transistors have progressed, and the gate insulating film constituting the transistor has also been thinned.
Conventionally, a silicon oxide film has been used as the gate insulating film. However, if the thickness of the silicon oxide film is reduced, the gate leakage current increases. Therefore, a so-called high-k film (high dielectric constant film) is used instead of the silicon oxide film.
By using such a high dielectric constant film, leakage current can be suppressed without deteriorating the driving capability of the transistor.
When a high dielectric constant film is used for the gate insulating film, an SiO ₂ film or an SiON film is formed on the substrate as an interface layer, and a high dielectric constant film such as hafnium oxide is formed on the interface layer (for example, a patent Reference 1).
Furthermore, there are Patent Documents 2 to 4 as techniques related to the present invention.

JP 2003-69011 A JP-A-2005-203671 JP 2002-305196 A Special table 2007-500946 gazette

Here, when a high dielectric constant film is used, there is a problem of a decrease in TDDB (Time Dependent Dielectric Breakdown) indicating a measure of the reliability of the gate insulating film.
This is presumed to be caused by the following. Atoms such as Hf constituting the high dielectric constant film diffuse to the interface layer, and Hf atoms enter the interface layer. In the interface layer, defects due to penetration of Hf atoms and the like are generated. It is considered that the reliability of the semiconductor device is lowered due to such defects. In particular, when the defect is formed on the substrate side of the interface layer, the leakage current may increase, and the reliability (for example, the lifetime) of the semiconductor device is particularly likely to decrease. Further, the influence on the reliability of the semiconductor device varies depending on the manner of occurrence of defects, and the reliability of the transistor, for example, the lifetime varies.

According to the present invention, a step of forming a silicon oxide film on a substrate, a step of introducing nitrogen into the silicon oxide film to form a silicon oxynitride film, Zr on the silicon oxynitride film, Forming a silicon oxide film on the substrate, and forming a silicon oxide film on the substrate at a temperature lower than 1050 ° C. Then, a method of manufacturing a semiconductor device is provided in which the silicon oxide film is heat-treated at 1050 ° C. or higher and 1100 ° C. or lower.
According to the invention, a step of forming a silicon oxide film on the substrate, a step of forming a silicon oxynitride film by introducing nitrogen into the silicon oxide film, and a step of forming on the silicon oxynitride film Forming a silicon oxide film on the substrate at a temperature of 1050 ° C. or higher and 1100 ° C. or lower on the substrate. A method of manufacturing a semiconductor device for forming a silicon oxide film is provided.

According to the present invention, in the step of forming the silicon oxide film on the substrate, after forming the silicon oxide film on the substrate, the silicon oxide film is heat-treated at 1050 ° C. or higher and 1100 ° C. or lower, or 1050 ° C. or higher. A silicon oxide film is formed on the substrate at 1100 ° C. or lower.
By doing so, the silicon oxide film is densified. For this reason, in the step of forming a silicon oxynitride film by introducing nitrogen into the silicon oxide film, nitrogen atoms are less likely to enter the silicon oxide film, and the nitrogen atoms are localized on the surface of the silicon oxynitride film.
The localized nitrogen atoms can prevent Zr atoms and Hf atoms from entering the silicon oxynitride film. Further, the densification of the silicon oxide film allows the Zr and Hf atoms to enter the silicon oxynitride film. Intrusion is prevented.
Thereby, defects due to Zr atoms and Hf atoms are less likely to occur in the silicon oxynitride film, and the reliability of the semiconductor device is improved.

  According to the present invention, a highly reliable semiconductor device is provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.
(First embodiment)
First, an outline of a method for manufacturing a semiconductor device according to the present embodiment will be described with reference to FIGS.
The manufacturing method of the semiconductor device 1 of the present embodiment includes a step of forming a silicon oxide film 12 on the substrate 11, a step of introducing nitrogen into the silicon oxide film 12 to form a silicon oxynitride film 13, Forming an insulating film 14 containing at least one of Zr and Hf on the silicon oxynitride film 13.
In the step of forming the silicon oxide film 12 on the substrate 11, after the silicon oxide film 12 is formed on the substrate 11, the silicon oxide film 12 is heat-treated at 1050 ° C. or more and 1100 ° C. or less.

Next, the manufacturing method of the semiconductor device of this embodiment will be described in detail.
First, a substrate 11 that is a semiconductor substrate is prepared. This substrate 11 is a substrate having at least a layer containing silicon as a main component on its surface, and is a silicon substrate in this embodiment.
Although not shown, the substrate 11 has an element formation region defined by STI (shallow trench isolation).

Next, as shown in FIG. 1A, a silicon oxide film 12 is formed on the substrate 11. The silicon oxide film 12 is formed by thermally oxidizing the substrate 11 at a temperature lower than 1050 ° C., for example, 850 ° C. or higher and 950 ° C. or lower in an oxygen atmosphere.
The thickness of the silicon oxide film 12 is preferably 2.5 nm or less, and more preferably 2.0 nm or less. The lower limit value of the silicon oxide film 12 is preferably 1.5 nm or more.
By setting the thickness of the silicon oxide film 12 to 2.5 nm or less, there is an effect of increasing the driving current of the transistor. Further, by setting the thickness of the silicon oxide film 12 to 1.5 nm or more, gate leakage current can be reliably prevented.

Next, the silicon oxide film 12 is heat-treated at 1050 ° C. or higher and 1100 ° C. or lower. At this time, an inert gas or nitrogen gas may be introduced as the non-oxidizing gas. The heat treatment of the silicon oxide film 12 is preferably performed in a nitrogen atmosphere or a mixed gas atmosphere of nitrogen and oxygen. By doing in this way, there exists an effect which suppresses the film thickness increase of a thin insulating film.
This heat treatment step and the above-described film formation step of the silicon oxide film 12 (step of thermally oxidizing the substrate 11) are performed continuously in the same chamber. Thereby, contamination of the silicon oxide film 12 can be prevented.
The heat treatment can be performed by lamp annealing or the like.
The heat treatment temperature is preferably 1050 ° C. or higher, more preferably 1075 ° C. or higher. By doing so, the silicon oxide film 12 can be reliably densified, and the interface roughness between the substrate 11 and the silicon oxide film 12 can be improved.
The heat treatment time is preferably 10 seconds or more and 120 seconds or less. By doing so, the silicon oxide film 12 can be reliably densified, and the roughness of the interface between the substrate 11 and the silicon oxide film 12 can be improved.
Note that the upper limit value of the heat treatment temperature is set to 1100 ° C. because it is possible to prevent crystal defects from occurring in the substrate 11 by performing the heat treatment at 1100 ° C. or less.

Next, nitrogen is introduced into the silicon oxide film 12 and nitridation is performed to form a silicon oxynitride film 13 (FIG. 1B). Examples of the nitriding method include a method of exposing the silicon oxide film 12 to a plasma containing nitrogen, and a method of heat-treating the silicon oxide film 12 in an atmosphere containing nitrogen such as ammonia or nitrogen dioxide. Among these, from the viewpoint of localizing nitrogen at a relatively high concentration on the surface, a method in which the silicon oxide film 12 is subjected to thermal plasma treatment in an atmosphere containing nitrogen is preferable.
At this time, since the silicon oxide film 12 is densified in the previous heat treatment step, the nitrogen atoms are localized in the surface layer of the silicon oxynitride film 13. In other words, nitrogen atoms are unlikely to enter the silicon oxynitride film 13.

Thereafter, as shown in FIG. 2, an insulating film 14 containing Hf, for example, an HfSiO (hafnium silicate) film is formed on the silicon oxynitride film 13. The HfSiO film is formed by using, for example, HTB (Hf (Ot-Bu) ₄ ) and monosilane (SiH ₄ ) by a CVD (chemical vapor deposition) method, an ALD (atomic layer deposition) method, or a sputtering method. For details, refer to JP-A-2006-93670.
Here, the insulating film 14 is a high-k film (an insulating film having a relative dielectric constant of 10 or more).

Thereafter, as shown in FIG. 3A, a polysilicon film 16 ′ to be the gate electrode 16 is formed on the insulating film 14. Next, as shown in FIG. 3B, the polysilicon film 16 ′ is selectively removed to form the gate electrode 16. Further, after the silicon oxynitride film 13 and the insulating film 14 are selectively removed using the gate electrode 16 as a mask (the gate insulating film is formed by the silicon oxynitride film 13 and the insulating film 14), as shown in FIG. Then, impurities are implanted into the substrate 11 to form source / drain regions 111A and 111B. Next, the substrate 11 is heated to, for example, 1050 ° C. to activate the impurities in the source / drain regions 111A and 111B. As for the junction formation technology, for example, an insulating film is formed on the side surface of the gate electrode to introduce impurities, or a source / drain extension structure that shallows only the junction at the gate end is known. The details may be omitted here.
In addition, when the gate electrode 16 is formed in the subsequent process of forming the insulating film 14, heat is applied to the substrate 11 when the impurities of the source / drain regions 111A and 111B are activated. The heat treatment temperature when activating the impurities in the drain regions 111A and 111B is the highest.
The semiconductor device 1 is manufactured through the above steps.

Next, the effect of this embodiment is demonstrated.
In this embodiment, after the silicon oxide film 12 is formed on the substrate 11, the silicon oxide film 12 is heat-treated at 1050 ° C. or higher and 1100 ° C. or lower.
By doing so, the silicon oxide film 12 is densified. Therefore, in the step of forming the silicon oxynitride film 13 by introducing nitrogen into the silicon oxide film 12, it becomes difficult for nitrogen atoms to enter the silicon oxide film, and the nitrogen atoms are localized on the surface of the silicon oxynitride film 13. Turn into.
The localized nitrogen atoms prevent Hf atoms from entering the silicon oxynitride film 13, and further, due to the densification of the silicon oxide film 12, Hf atoms enter the silicon oxynitride film 13. Is prevented.
Thereby, defects due to Hf atoms are less likely to occur in the silicon oxynitride film 13 and the reliability of the semiconductor device 1 is improved.

  In the present embodiment, the thickness of the silicon oxide film 12 is 2.5 nm or less, and since the thickness is relatively thin, the Hf atoms easily enter the interface side between the silicon oxynitride film 13 and the substrate 11. It has become. In such a semiconductor device 1, it is extremely useful to prevent Hf atoms from entering the silicon oxynitride film 13 as described above.

  In the present embodiment, in the subsequent process of forming the insulating film 14, when the gate electrode 16 is formed, when the impurities of the source / drain regions 111 A and 111 B are activated, heat is applied to the substrate 11, Although the substrate 11 is subjected to heat treatment, in such heat treatment, Hf atoms may diffuse to the silicon oxynitride film 13 side. In the present embodiment, the silicon oxide film 12 is densified, and nitrogen atoms are localized on the surface of the silicon oxynitride film 13 to prevent intrusion of Hf atoms. Intrusion of atoms into the silicon oxynitride film 13 can be effectively prevented.

  In the present embodiment, the silicon oxide film 12 is formed at a temperature lower than the heat treatment temperature. Specifically, the silicon oxide film 12 is formed by heat-treating the substrate 11 at 850 ° C. or more and 950 ° C. or less. Thereby, the thickness and the like of the silicon oxide film 12 can be accurately controlled.

(Second embodiment)
In the embodiment, when the silicon oxide film 12 is formed, the silicon oxide film 12 is heat-treated at 1050 ° C. or higher and 1100 ° C. or lower. In contrast, in the present embodiment, the silicon oxide film 12 is formed on the substrate 11 at 1050 ° C. or higher and 1100 ° C. or lower. The other points are the same as in the above embodiment.
When the silicon oxide film 12 is formed, the substrate 11 is heated to form a thermal oxide film at 1050 ° C. or higher and 1100 ° C. or lower, and no heat treatment is performed. Thereby, the densified silicon oxide film 12 can be formed.
The formation temperature of the silicon oxide film 12 is preferably 1050 ° C. or higher, and particularly preferably 1075 ° C. or higher. By doing so, the silicon oxide film 12 can be reliably densified.
The upper limit of the temperature is set to 1100 ° C. because the formation of the silicon oxide film 12 at 1100 ° C. or less can prevent the substrate 11 from generating crystal defects.

According to such this embodiment, the same effect as 1st embodiment can be produced, and the following effect can be produced.
In this embodiment, since the silicon oxide film 12 is formed on the substrate at 1050 ° C. or higher and 1100 ° C. or lower, the silicon oxide film 12 is formed as compared with the case where the heat treatment is performed after the silicon oxide film 12 is formed. The process can be simplified.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in each of the above-described embodiments, the insulating film 14 is formed by a chemical vapor deposition (CVD) method or an atomic layer deposition (ALD) method. However, the present invention is not limited to this. For example, the PVD method is formed on the silicon oxynitride film 13. Thus, the insulating film 14 which is a hafnium silicate film may be formed by forming a Hf film and then performing heat treatment.

Furthermore, in the above-described embodiment, the hafnium silicate film is formed as the high-k film. However, the present invention is not limited to this, and any insulating film containing at least one of Zr and Hf may be used. An oxide film of Zr and Hf, a silicate film of Zr and Hf, and an oxynitride film of Zr and Hf may be used. Specifically, for example, a ZrSiO film or the like may be used.
The method of forming these insulating films may be the same as that in the above embodiment, or may be by a CVD method or an ALD method.
Since Zr has the same atomic radius as that of Hf atoms, it is considered that intrusion into the silicon oxynitride film can be prevented even when an insulating film using these metal atoms is formed.

Next, examples of the present invention will be described.
Example 1
A semiconductor device was manufactured by the same method as in the first embodiment.
Specifically, the silicon substrate was thermally oxidized at 950 ° C. to form a silicon oxide film. The thickness of this silicon oxide film was 2 nm.
Next, the silicon oxide film was heat-treated at 1075 ° C. for 60 seconds. Thereafter, nitrogen was introduced into the silicon oxide film to form a silicon oxynitride film. Specifically, the silicon oxide film was heat-treated at 400 ° C. in a plasma atmosphere and a nitrogen atmosphere to form a silicon oxynitride film.
Next, a hafnium silicate film was formed on the silicon oxynitride film by a CVD method using HTB (Hf (Ot—Bu) ₄ ) and monosilane (SiH ₄ ).
Next, a gate electrode was formed on the hafnium silicate film, and arsenic (N-type region) and boron (P-type region) were implanted into the substrate to form source / drain regions. Thereafter, the substrate was heated at 1050 ° C. to activate the source / drain regions.
Furthermore, the gate insulating film was formed by selectively removing the hafnium silicate film and the silicon oxynitride film using the gate electrode as a mask.
Through the above steps, a semiconductor device was obtained.

(Example 2)
Example 2 is the same as Example 1 except that the heat treatment temperature of the silicon oxide film is set to 1050 ° C.

(Example 3)
A semiconductor device was manufactured by the same method as in the second embodiment.
Specifically, the silicon substrate was thermally oxidized at 1050 ° C. to form a silicon oxide film. The thickness of this silicon oxide film was 2 nm.
Thereafter, nitrogen was introduced into the silicon oxide film to form a silicon oxynitride film. Specifically, the silicon oxide film was heat-treated at 400 ° C. in a plasma atmosphere and a nitrogen atmosphere to form a silicon oxynitride film.
Next, a hafnium silicate film was formed on the silicon oxynitride film by a CVD method using HTB (Hf (Ot—Bu) ₄ ) and monosilane (SiH ₄ ).
Next, a gate electrode was formed on the hafnium silicate film, and arsenic (N-type region) and boron (P-type region) were implanted into the substrate to form source / drain regions. Thereafter, the substrate was heated at 1050 ° C. to activate the source / drain regions.
Furthermore, the gate insulating film was formed by selectively removing the hafnium silicate film and the silicon oxynitride film using the gate electrode as a mask.
Through the above steps, a semiconductor device was obtained.

(Comparative Example 1)
The silicon substrate was thermally oxidized at 950 ° C. to form a silicon oxide film. The thickness of this silicon oxide film was 2 nm.
Thereafter, nitrogen was introduced into the silicon oxide film to form a silicon oxynitride film. Specifically, the silicon oxide film was heat-treated at 400 ° C. in a plasma atmosphere and a nitrogen nitride atmosphere to form a silicon oxynitride film.
Next, a hafnium silicate film was formed on the silicon oxynitride film by a CVD method using HTB (Hf (Ot—Bu) ₄ ) and monosilane (SiH ₄ ).
Further, a gate electrode was formed on the hafnium silicate film, and arsenic (N-type region) and boron (P-type region) were implanted into the substrate to form source / drain regions. Thereafter, the substrate was heated at 1050 ° C. to activate the source / drain regions.
Furthermore, the gate insulating film was formed by selectively removing the hafnium silicate film and the silicon oxynitride film using the gate electrode as a mask.
Through the above steps, a semiconductor device was obtained.

(Comparative Example 2)
The silicon substrate was thermally oxidized at 950 ° C. to form a silicon oxide film. The thickness of this silicon oxide film was 2 nm.
Next, the silicon oxide film was heat-treated at 1000 ° C. for 60 seconds. Thereafter, nitrogen was introduced into the silicon oxide film to form a silicon oxynitride film. Specifically, the silicon oxide film was heat-treated at 400 ° C. in a plasma atmosphere and a nitrogen nitride atmosphere to form a silicon oxynitride film.
A hafnium silicate film was formed on the silicon oxynitride film by a CVD method using HTB (Hf (Ot-Bu) ₄ ) and monosilane (SiH ₄ ).
Next, a gate electrode was formed on the hafnium silicate film, and arsenic (N-type region) and boron (P-type region) were implanted into the substrate to form source / drain regions. Thereafter, the substrate was heated at 1050 ° C. to activate the source / drain regions.
Furthermore, the gate insulating film was formed by selectively removing the hafnium silicate film and the silicon oxynitride film using the gate electrode as a mask.
Through the above steps, a semiconductor device was obtained.

(result)
(Weibull plot)
The TDDB (Time Dependent Dielectric Breakdown) characteristics of the semiconductor devices of Example 1 and Comparative Example 1 were measured (the temperature until the breakdown was generated by continuously applying a voltage at which the insulating film was not broken down was measured). Then, the measurement results were Weibull plotted to evaluate the reliability (lifetime) of the semiconductor device.
Here, the Weibull plot is a plot in which the vertical axis is an index W calculated from the cumulative failure rate F of the semiconductor device in which dielectric breakdown has occurred, and the log scale of the stress application time t is the horizontal axis. The index W is calculated by the following formula.
W = ln [ln {1 / (1-F)}]
Here, as shown in FIG. 5, the greater the slope of the Weibull plot, the longer the lifetime.

  The results are shown in FIG. It can be seen that Example 1 has a larger Weibull plot slope and a longer life compared to Comparative Example 1. FIG. 6 shows the measurement result of the gate insulating film by RBS (Rutherford backscattering) in Example 1. According to this, it can be seen that Hf atoms do not penetrate to the interface side between the silicon substrate and the silicon oxynitride film, but are localized on the silicon oxynitride film surface side.

(Examples 2 and 3 and Comparative Example 2)
Similar to Example 1 and Comparative Example 1, the results of evaluating the TDDB characteristics of Examples 2, 3 and Comparative Example 2 and obtaining the slope of the Weibull plot are shown in FIG. Compared with Comparative Examples 1 and 2, Examples 1, 2 and 3 have a large Weibull plot slope and can be said to have a long life.
The above results show that the silicon oxide film can be densified at a temperature of 1050 ° C. or higher. Further, the densification of the silicon oxide film suppresses diffusion of nitrogen introduced in the subsequent process toward the silicon substrate. Then, it is considered that diffusion of hafnium atoms toward the silicon substrate is suppressed by localization of nitrogen and densification of the silicon oxide film. As a result, it is considered that the slope of the Weibull plot increases and the life of the semiconductor device is improved.

It is a figure which shows the manufacturing process of the semiconductor device concerning one Embodiment of this invention. It is a figure which shows the manufacturing process of the semiconductor device concerning one Embodiment of this invention. It is a figure which shows the manufacturing process of the semiconductor device concerning one Embodiment of this invention. It is a figure which shows the inclination of Example 1 and the Weibull plot of the comparative example 1. FIG. It is a figure which shows the relationship between the inclination of a Weibull plot, and a lifetime. It is a figure which shows the elemental-analysis result of the gate insulating film of Example 1. It is a figure which shows the inclination of the Weibull plot of an Example and a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor device 11 Board | substrate 12 Silicon oxide film 13 Silicon oxynitride film 14 Insulating film 16 Gate electrode 16 'Polysilicon film 111A, 111B Source / drain region

Claims (8)

Forming a silicon oxide film on the substrate;
Introducing nitrogen into the silicon oxide film to form a silicon oxynitride film;
Forming an insulating film containing at least one of the metal elements of Zr and Hf on the silicon oxynitride film,
In the step of forming a silicon oxide film on the substrate,
A method of manufacturing a semiconductor device, comprising: forming a silicon oxide film on the substrate at a temperature lower than 1050 ° C .; and thereafter heat-treating the silicon oxide film at a temperature of 1050 ° C. or higher and 1100 ° C. or lower. Forming a silicon oxide film on the substrate;
Introducing nitrogen into the silicon oxide film to form a silicon oxynitride film;
Forming an insulating film containing at least one of the metal elements of Zr and Hf on the silicon oxynitride film,
In the step of forming a silicon oxide film on the substrate,
A method of manufacturing a semiconductor device, wherein a silicon oxide film is formed on the substrate at 1050 ° C. or higher and 1100 ° C. or lower. In the manufacturing method of the semiconductor device according to claim 1 or 2,
A method of manufacturing a semiconductor device, wherein the silicon oxide film has a thickness of 2.5 nm or less. In the manufacturing method of the semiconductor device according to claim 1,
The method of manufacturing a semiconductor device, wherein the insulating film and the silicon oxynitride film are gate insulating films. In the manufacturing method of the semiconductor device according to claim 1,
In the step of forming a silicon oxynitride film by introducing nitrogen into the silicon oxide film, the silicon oxide film is processed in a plasma atmosphere containing nitrogen to thereby form a silicon oxynitride film. Production method. In the manufacturing method of the semiconductor device in any one of Claims 1 thru | or 5,
In the step of forming an insulating film on the silicon oxynitride film,
A method for manufacturing a semiconductor device, comprising: forming an insulating film containing at least one of Zr and Hf on a silicon oxynitride film by a CVD method, an ALD method, or a sputtering method. In the manufacturing method of the semiconductor device according to claim 1,
A method for manufacturing a semiconductor device, comprising: a step of heat-treating the semiconductor device after the step of forming an insulating film. In the manufacturing method of the semiconductor device according to claim 1,
In the step of forming a silicon oxide film on the substrate,
After forming a silicon oxide film on the substrate at less than 1050 ° C., heat-treating the silicon oxide film at 1050 ° C. or more and 1100 ° C. or less,
The method of manufacturing a semiconductor device, wherein the heat treatment is performed in a nitrogen atmosphere or a mixed atmosphere of nitrogen and oxygen.

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