JP4255203B2 - Manufacturing method of semiconductor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device and a manufacturing method thereof, and more particularly to a semiconductor device having a polymetal gate electrode in which a polysilicon film and a metal film are deposited and a manufacturing method thereof.
[0002]
[Prior art]
Recently, with higher integration and higher speed of CMOS transistors, lower resistance of the gate electrode is required.
[0003]
As a technique for reducing the resistance of the gate electrode, a semiconductor device having a so-called polymetal structure in which a refractory metal and polysilicon are laminated has been proposed. Such a semiconductor device having a polymetal structure is, for example, Low-resistivity poly-metal gate electrode durable for high-temperature processing, Y. Akasaka et al., IEEE Trans.On electron Dev. 43 , 1864 (1996).
[0004]
A proposed semiconductor device having a polymetal structure will be described with reference to FIG. FIG. 23 is a cross-sectional view showing a proposed semiconductor device having a polymetal structure.
[0005]
As shown in FIG. 23, a gate insulating film 112 made of a silicon oxynitride film is formed on the silicon substrate 110. On the gate insulating film 112, there are a polysilicon film 114, a buffer film 116 made of WSiN formed on the polysilicon film 114, and a metal film 118 made of W (tungsten) formed on the buffer film 116. A gate electrode 120 having a stacked structure is formed. The buffer film 116 is for preventing the polysilicon film 114 and the metal film 118 from reacting to form a highly resistant tungsten silicide. A cap film 122 made of a silicon nitride film is formed on the gate electrode 120.
[0006]
A silicon oxide film 123 is formed on the side wall portion of the polysilicon film 114. The silicon oxide film 123 is for removing damage introduced when the gate electrode 120 is patterned and for reducing electric field concentration.
[0007]
Sidewall insulating films 126 are formed on the side walls of the gate electrode 120 and the silicon oxide film 123. In the silicon substrate 110 on both sides of the gate electrode 120, a source / drain diffusion layer 128 having an extension source / drain structure composed of an impurity diffusion region 128a and an impurity diffusion region 128b is formed.
[0008]
The gate insulating film 112 has a high nitrogen concentration in a region 130 represented by shading in the drawing. Since the region 130 having a high nitrogen concentration is formed in the gate insulating film 112, impurities such as boron introduced into the polysilicon film 114 are suppressed from escaping to the silicon substrate 110 side, and the extension source / drain is removed. The impurity introduced into the impurity diffusion region 128a is suppressed from being absorbed by the gate insulating film 112, the sidewall insulating film 126, and the like. Such a principle is disclosed, for example, in High Performance & Highly Reliable Deep Submicron CMOSFET using Nitrided-Oxide, K. Irino et al., 1999 Symp. On VLSI Technology, 9A-2.
[0009]
Tungsten used for the metal film 118 is a material that is easily oxidized. Tungsten is oxidized to WO _Three Then, the resistance becomes high, and the original purpose of the semiconductor device having a polymetal structure, that is, reducing the resistance of the gate electrode 120 cannot be achieved. Therefore, when the silicon oxide film 123 is formed, it is necessary to selectively form the silicon oxide film 123 only on the side wall portion of the polysilicon film 114 without oxidizing the metal film 118 and the like. Therefore, in the proposed semiconductor device having a polymetal structure, after the gate electrode 120 is patterned, H having an oxidizing action is used. ₂ O and H having a reducing action ₂ The silicon oxide film 123 is selectively formed only on the side wall portion of the polysilicon film 114 without oxidizing the metal film 118 by performing heat treatment in an atmosphere including
[0010]
In such a semiconductor device having a polymetal structure, a metal film is used for the gate electrode. Therefore, the resistance of the gate electrode can be reduced, which can contribute to higher speed and higher integration.
[0011]
[Problems to be solved by the invention]
However, in the proposed semiconductor device, when the silicon oxide film 123 is formed on the side surface of the polysilicon film 114, the oxidation also proceeds at the interface between the silicon substrate 110 and the gate insulating film 112, so that the nitrogen concentration is high. The region 130 may be separated from the interface between the silicon substrate 110 and the gate insulating film 112. If the region 130 having a high nitrogen concentration does not exist at the interface between the silicon substrate 110 and the gate insulating film 112 below the end of the gate electrode 120, the hot carrier resistance may deteriorate, and the polysilicon film Impurities such as boron introduced into 113 may escape to the silicon substrate 110 side.
[0012]
Further, in the proposed semiconductor device, impurities such as boron introduced into the polysilicon film 114 may escape into the silicon oxide film 123 due to a high-temperature heat treatment process, and the polysilicon film 114 is depleted. Sometimes occurred. For this reason, good BT stress resistance cannot be obtained, and the gate resistance may not be sufficiently reduced.
[0013]
An object of the present invention is to provide a semiconductor device that can suppress depletion of a gate electrode and ensure hot carrier resistance in a semiconductor device having a polymetal structure, and a method for manufacturing the same.
[0014]
[Means for Solving the Problems]
The above purpose is A step of forming a gate insulating film on the silicon substrate; a step of forming a gate electrode having a polysilicon film and a metal film formed on the polysilicon film on the gate insulating film; Then, heat treatment is performed in a gas atmosphere having an oxidizing action and a reducing action to selectively form an insulating film on the side wall portion of the polysilicon film, and to insulate the silicon substrate and the gate under the end of the gate electrode. A method of manufacturing a semiconductor device, comprising: introducing nitrogen into an interface with the film Is achieved. Thus, since nitrogen is introduced at a high concentration at the interface between the silicon substrate and the gate insulating film, a semiconductor device with good hot carrier resistance can be provided.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
The semiconductor device and the manufacturing method thereof according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a sectional view of the semiconductor device according to the present embodiment. FIG. 2 is a graph showing a nitrogen concentration distribution in a region near the interface between the gate insulating film and the silicon substrate below the end of the gate electrode. 3 to 6 are process cross-sectional views illustrating the semiconductor device manufacturing method according to the present embodiment. FIG. 7 is a time chart showing the formation process of the silicon oxynitride film and the high nitrogen concentration region according to the present embodiment. FIG. 8 is a graph showing the presence or absence of oxidation of silicon and tungsten.
[0016]
As shown in FIG. 1, a gate electrode 20 is formed on a silicon substrate 10 via a gate insulating film 12 made of a silicon oxynitride film.
[0017]
The gate electrode 20 includes a polysilicon film 14 formed on the gate insulating film 12, a buffer film 16 made of WSiN formed on the polysilicon film 14, and a metal film made of W formed on the buffer film 16. 18 and a laminated structure. The buffer film 16 is intended to prevent the polysilicon film 14 and the metal film 18 from reacting to form tungsten silicide having a high resistance.
[0018]
A cap film 22 made of a silicon nitride film is formed on the gate electrode 20.
[0019]
A silicon oxynitride film 24 is formed on the side wall portion of the polysilicon film 14. The silicon oxynitride film 24 is for removing damage introduced when the gate electrode 20 is patterned and for reducing electric field concentration.
[0020]
A sidewall insulating film 26 is formed on the side walls of the gate electrode 20 and the silicon oxynitride film 24. In the silicon substrate 10 on both sides of the gate electrode 20, a source / drain diffusion layer 28 having an extension source / drain structure composed of an impurity diffusion region 28a and an impurity diffusion region 28b is formed.
[0021]
The semiconductor device according to the present embodiment has one of main features in that a region 30 having a high nitrogen concentration is formed at the interface between the gate insulating film 12 and the silicon substrate 10 below the end of the gate electrode 20.
[0022]
That is, the nitrogen concentration at the interface between the gate insulating film 12 and the silicon substrate 10 below the end of the gate electrode 20 is directly below the gate electrode 20, that is, below the region excluding the end of the gate electrode 20. It is higher than the nitrogen concentration.
[0023]
The regions 30 and 32 where the nitrogen concentration is high are represented by shading in the figure. In the present specification, such a region where the nitrogen concentration is high is referred to as a high nitrogen concentration region.
[0024]
In the present embodiment, the nitrogen concentration at the interface between the gate insulating film 12 and the silicon substrate 10 below the end of the gate electrode 20 is higher than the nitrogen concentration in the gate insulating film 12 immediately below the gate electrode 20. This is because the nitrogen high concentration region 30 is formed after the gate electrode 20 is patterned, as will be described later.
[0025]
FIG. 2 is a graph showing a nitrogen concentration distribution in a region near the interface between the gate insulating film and the silicon substrate below the end of the gate electrode. The horizontal axis represents the depth, and the vertical axis represents the nitrogen concentration. In the drawing, the interface between the silicon substrate 10 and the gate insulating film 12 is represented by a broken line.
[0026]
As can be seen from FIG. 2, the nitrogen concentration is high in the silicon substrate 10, the gate insulating film 12, and the region near the interface.
[0027]
In the proposed semiconductor device shown in FIG. 23, when the oxide film is selectively formed on the side wall portion of the polysilicon film, the oxidation proceeds from the interface between the silicon substrate and the silicon nitride film, and the high nitrogen concentration region is It was separated from the interface between the silicon substrate and the gate insulating film. For this reason, hot carrier resistance may deteriorate, and impurities such as boron may be lost from the source / drain diffusion layer. On the other hand, in this embodiment, since the nitrogen high concentration region 30 is formed at the interface between the silicon substrate 10 and the gate insulating film 12 below the end of the gate electrode 20, good hot carrier resistance can be obtained. In addition, impurities such as boron can be prevented from escaping from the source / drain diffusion layer.
[0028]
The semiconductor device according to the present embodiment also has one of main features in that a region 32 having a high nitrogen concentration is formed at the interface between the polysilicon film 14 and the silicon oxynitride film 24. In the present embodiment, since the high nitrogen concentration region 32 is formed at the interface between the polysilicon film 14 and the silicon nitride oxide film 24, impurities such as boron introduced into the polysilicon film 14 are formed in the silicon nitride oxide film 24. It can be suppressed from coming off. Therefore, according to the present embodiment, depletion of the polysilicon film 14 can be prevented, and a semiconductor device with good electrical characteristics can be provided.
[0029]
Next, the method for fabricating the semiconductor device according to the present embodiment will be explained with reference to FIGS. 3 to 6 are process cross-sectional views illustrating the semiconductor device manufacturing method according to the present embodiment.
[0030]
First, as shown in FIG. 3A, a gate insulating film 12 made of a silicon oxynitride film having a thickness of 4.5 nm is formed on a silicon substrate 10. The gate insulating film 12 can be formed, for example, by wet-oxidizing the surface of the silicon substrate 10 and then performing a heat treatment in an NO gas atmosphere.
[0031]
Next, a polysilicon film 14 having a thickness of 70 nm is formed on the silicon substrate 10 on which the gate insulating film 12 is formed by, for example, a CVD method.
[0032]
Next, impurities are introduced into the polysilicon film 14 by ion implantation. When forming a p-type polysilicon film, for example, acceleration energy is 5 keV, and a dose amount is 2 × 10. ¹⁵ cm ^-2 Then, B (boron) ions are implanted. Further, when forming an n-type polysilicon film, for example, acceleration energy is 10 keV, and a dose amount is 4 × 10. ¹⁵ cm ^-2 Then, P (phosphorus) ions are implanted.
[0033]
Next, a buffer film 16 made of WN having a thickness of 5 nm is formed on the polysilicon film 14 by, eg, sputtering.
[0034]
Next, a metal film 18 of W having a thickness of 40 nm is formed on the buffer film 16 by, for example, sputtering.
[0035]
Next, a cap film 22 made of SiN having a thickness of 200 nm is formed on the metal film 18 by, eg, CVD (see FIG. 3B).
[0036]
Next, the cap film 22, the metal film 18, the buffer film 16, and the polysilicon film 14 are patterned by using a photolithography technique, and the polysilicon film 14, the buffer film 16, and the upper surface covered with the cap film 22 A gate electrode 20 having a polymetal structure made of the metal film 18 is formed (see FIG. 4A).
[0037]
Next, a silicon oxynitride film 24 is selectively formed on the side wall portion of the polysilicon film 14 without oxidizing the metal film 18 and the buffer film 16, and the silicon substrate 10 below the end of the gate electrode 20 is formed. A high nitrogen concentration region 30 is formed at the interface with the gate insulating film 12, and a high nitrogen concentration region 32 is formed at the interface between the polysilicon film 14 and the silicon oxynitride film 24.
[0038]
Such silicon oxynitride film 24 and nitrogen high concentration regions 30 and 32 can be formed by a process as shown in FIG. FIG. 7 is a time chart showing the formation process of the silicon oxynitride film and the nitrogen high concentration region. 7A shows the temperature in the film forming chamber, FIG. 7B shows the flow rate of the gas introduced into the film forming chamber, and FIG. 7C shows the pressure in the film forming chamber. Yes.
[0039]
That is, first, as shown in FIG. 7, the pressure in the film forming chamber is atmospheric pressure, that is, about 101.3 kPa, the temperature in the film forming chamber is set to 350 ° C., and N is flowed into the film forming chamber at a flow rate of 10 SLM. ₂ Introduce gas. After this, N ₂ The gas flow rate is 20 SLM. Note that the reason why the temperature in the film formation chamber is set to a low value of 350 ° C. is that when the film formation chamber is heated to a high temperature when oxygen remains in the film formation chamber, the side walls of the metal film 18 and the like are oxidized. This is because there is a risk of it.
[0040]
Next, N ₂ The introduction of gas is stopped and the film formation chamber is evacuated.
[0041]
Next, N in the film formation chamber at a flow rate of 5 SLM. ₂ Gas is introduced and the pressure in the deposition chamber is set to about 4 kPa. Thereafter, the temperature in the film formation chamber is raised to 800 ° C. When the temperature in the deposition chamber rises to 800 ° C, N ₂ Stop introducing gas.
[0042]
Next, in the film formation chamber, H ₂ Gas, H ₂ O gas and NO gas will be introduced sequentially. First, H at a flow rate of 1 SLM ₂ Start introducing gas. Next, H at a flow rate of 0.4 SLM ₂ Start introducing O gas. Thereafter, introduction of NO gas is started at a flow rate of 0.5 SLM.
[0043]
The NO gas introduced into the deposition chamber functions as a nitrogen supply source, and H ₂ O gas functions as an oxidizing gas and H ₂ The gas functions as a reducing gas.
[0044]
When heat treatment is performed at 800 ° C. for 60 minutes in such an atmosphere, the side wall portion of the polysilicon film 14 is selectively oxynitrided without oxidizing the metal film 18 and the buffer film 16, and the polysilicon film A silicon nitride film 24 having a film thickness of 10 nm is formed on the side wall portion 14. Further, due to this oxynitridation, an oxynitride film is grown on the gate insulating film 12 exposed on the silicon substrate 10 by about 2.7 nm. Also, by this oxynitridation, a high nitrogen concentration region 30 is formed at the interface between the silicon substrate 10 and the gate insulating film 12 below the end of the gate electrode 20, and the interface between the polysilicon film 14 and the silicon nitride oxide film 24 Thus, a high nitrogen concentration region 32 is formed.
[0045]
FIG. 8 is a graph showing the presence or absence of oxidation of silicon and tungsten. The horizontal axis indicates the film formation temperature, and the vertical axis indicates H ₂ Gas and H ₂ The partial pressure ratio with O gas is shown. This graph is taken from N. Yamamoto et al., In Proc. 15th SSDM, 94 (1983).
[0046]
As can be seen from FIG. ₂ Gas and H ₂ If the partial pressure ratio with the O gas is set within the hatched range, only Si is oxidized without oxidizing W.
[0047]
Therefore, H ₂ Gas and H ₂ When film formation is performed with the partial pressure ratio with O gas set within the hatched range in FIG. 8, the side wall portion of the polysilicon film 14 is selectively oxynitrided without oxidizing the metal film 18. It is thought that you can.
[0048]
For example, when the temperature in the deposition chamber is 800 ° C., H ₂ Against H ₂ The partial pressure ratio of O is 1 × 10 ^-8 ~ 4x10 ^-1 It is considered to be set within the range of.
[0049]
The selective oxidation utilizes the fact that the Gibbs free energy for producing the silicon oxide film is larger than the Gibbs free energy for producing the metal oxide. W used in the present embodiment is a metal that is easily oxidized. For example, the free energy of Gibbs at 800 ° C. is 99 kcal.
[0050]
Here, for other metal materials, the Gibbs free energy at 800 ° C. was examined. As a result, Ni was 34 kcal, Co was 76 kcal, Cr was 101 kcal, and Mo was 95 kcal. The Gibbs free energy of these metallic materials is approximately equal to or less than that of W Gibbs free energy.
[0051]
Therefore, even when these metals are used as the material of the metal film 18, it is considered that selective oxidation can be performed under the same conditions as in this embodiment.
[0052]
Moreover, it is considered that noble metals such as Au, Ag, and Pt are not oxidized at 800 ° C. Therefore, even when these noble metals are used as the material of the metal film 18, it is considered that selective oxidation can be performed.
[0053]
In the above description, the flow rate of NO gas is 0.5 SLM, but the flow rate of NO gas is not limited to 0.5 SLM. For example, the flow rate of NO gas can be set as appropriate within a range of 1 SLM or less.
[0054]
Next, as shown in FIG. ₂ O gas, H ₂ The introduction of gas will be stopped sequentially.
[0055]
Next, N in the film formation chamber at a flow rate of 5 SLM. ₂ Introduce gas. Thereafter, the temperature in the deposition chamber is lowered to 300 ° C.
[0056]
Next, when the temperature in the film formation chamber decreases to 300 ° C., N in the film formation chamber ₂ Stop introducing gas. N ₂ When the introduction of the gas is stopped, the film formation chamber is in a vacuum state.
[0057]
Next, N in the film formation chamber at a flow rate of 20 SLM. ₂ Introduce gas. As a result, the pressure in the deposition chamber rises to atmospheric pressure. After this, N into the film formation chamber ₂ The amount of gas introduced is 10 SLM.
[0058]
Thus, the silicon nitride film 24 is selectively formed on the side wall portion of the polysilicon film 14, and the high nitrogen concentration region 30 is formed at the interface between the silicon substrate 10 and the gate insulating film 12 below the end of the gate electrode 20. In addition, a high nitrogen concentration region 32 is formed at the interface between the polysilicon film 14 and the silicon oxynitride film 24 (see FIG. 4B).
[0059]
Next, ion implantation is performed using the gate electrode 20 as a mask, thereby forming an impurity diffusion region 28a constituting a shallow region of the extension source / drain in the silicon substrate 10 on both sides of the gate electrode 20 (FIG. 5A). reference). In the case of forming an impurity diffusion region of a p-type MOS transistor, for example, acceleration energy is 10 keV and a dose is 5 × 10. ¹⁴ cm ^-2 And BF ₂ Ions are implanted. Further, when forming an impurity diffusion region of an nMOS transistor, for example, acceleration energy is 15 keV and a dose amount is 5 × 10. ¹⁴ cm ^-2 Then, As ions are implanted.
[0060]
Next, a 20 nm-thickness silicon nitride film is formed on the entire surface by, eg, CVD. Thereafter, the silicon nitride film is anisotropically etched to form a sidewall insulating film 26 made of a silicon nitride film on the side walls of the gate electrode 20 and the silicon nitride oxide film 24 (see FIG. 5B).
[0061]
Next, ion implantation is performed using the gate electrode 20 and the sidewall insulating film 26 as a mask, thereby forming an impurity diffusion region 28b constituting a deep region of the extension source / drain. In the case of forming an impurity diffusion region of a pMOS transistor, for example, acceleration energy is 45 keV and a dose amount is 3 × 10. ¹⁵ cm ^-2 And BF ₂ Ions are implanted. Further, when forming an impurity diffusion region of an nMOS transistor, for example, acceleration energy is 50 keV, and a dose amount is 3 × 10. ¹⁵ cm ^-2 Then, As ions are implanted.
[0062]
Next, heat treatment is performed, for example, at 950 ° C. for 10 seconds in a nitrogen atmosphere to activate the ions introduced into the impurity diffusion regions 28 a and 28 b, thereby forming the source / drain diffusion layer 28.
[0063]
Thus, a MOS transistor having a polymetal gate electrode 20 is formed.
[0064]
As described above, according to the present embodiment, after patterning the gate electrode, heat treatment is performed in a gas atmosphere containing nitrogen atoms and having an oxidizing action and a reducing action. In addition to forming the nitrided oxide film, a high nitrogen concentration region can be formed at the interface between the polysilicon film and the silicon nitrided oxide film. Since a high nitrogen concentration region is formed at the interface between the polysilicon film and the silicon oxynitride film, according to this embodiment, depletion of the polysilicon film can be suppressed.
[0065]
In addition, according to the present embodiment, after patterning the gate electrode, the heat treatment is performed in a gas atmosphere containing nitrogen atoms and having an oxidizing action and a reducing action. A high nitrogen concentration region can be formed at the interface with the insulating film. Since a high nitrogen concentration region is formed at the interface between the silicon substrate and the gate insulating film, according to this embodiment, a semiconductor device with good hot carrier resistance can be provided.
[0066]
(Modification (Part 1))
A method for manufacturing a semiconductor device according to the first modification of the present embodiment will be described with reference to FIGS. FIG. 9 is a time chart showing the formation process of the silicon oxynitride film and the high nitrogen concentration region according to this modification.
[0067]
In the method of manufacturing a semiconductor device according to this modification, N is used as a nitrogen supply source when the silicon oxynitride film 26 and the nitrogen high concentration regions 30 and 32 are formed. ₂ The main feature is in using O gas.
[0068]
First, the temperature in the deposition chamber is increased to 800 ° C., and N ₂ Since the process until the gas introduction is stopped is the same as that of the semiconductor device manufacturing method according to the first embodiment shown in FIG.
[0069]
Next, as shown in FIG. ₂ Gas, H ₂ O gas, N ₂ O gas will be introduced sequentially. First, H at a flow rate of 1 SLM ₂ Start introducing gas. Next, H at a flow rate of 0.4 SLM ₂ Start introducing O gas. After this, N at a flow rate of 5 SLM ₂ Start introducing O gas. N ₂ O gas is thermally decomposed into NO gas and functions as a nitrogen supply source.
[0070]
N ₂ The flow rate of the O gas is not limited to 5 SLM, and may be set as appropriate within a range of 5 SLM or less, for example. H ₂ O gas and H ₂ The partial pressure ratio with the gas may be appropriately set under the condition that the silicon oxynitride film 24 can be formed on the side wall portion of the polysilicon film 14 without oxidizing the metal film 18 and the buffer film 16.
[0071]
In such an atmosphere, for example, when heat treatment is performed at 800 ° C. for 60 minutes, a silicon oxynitride film 24 is selectively formed on the side wall portion of the polysilicon film 14, and below the end portion of the gate electrode 20. A high nitrogen concentration region 30 is formed at the interface between the silicon substrate 10 and the gate insulating film 12, and a high nitrogen concentration region 32 is further formed at the interface between the polysilicon film 14 and the silicon oxynitride film 24.
[0072]
Next, N ₂ O gas, H ₂ Gas, H ₂ The introduction of O gas into the film formation chamber will be stopped sequentially.
[0073]
The subsequent processes are the same as those of the semiconductor device manufacturing method according to the first embodiment shown in FIG.
[0074]
Thus, N as a nitrogen supply source ₂ Even when O gas is used, a semiconductor device similar to that of the first embodiment shown in FIG. 1 can be manufactured.
[0075]
(Modification (Part 2))
A method for manufacturing a semiconductor device according to the second modification of the present embodiment will be described with reference to FIGS. FIG. 10 is a time chart showing a process for forming a silicon oxynitride film and a high nitrogen concentration region according to this modification.
[0076]
In the semiconductor device manufacturing method according to this modification, NH is used as a nitrogen supply source when the silicon oxynitride film 24 and the nitrogen high concentration regions 30 and 32 are formed. _Three The main feature is the introduction of gas.
[0077]
First, the temperature in the deposition chamber is increased to 800 ° C., and N ₂ Since the process until the gas introduction is stopped is the same as that of the semiconductor device manufacturing method according to the first embodiment shown in FIG.
[0078]
Next, as shown in FIG. ₂ Gas, H ₂ O gas, NH _Three Gas will be introduced sequentially. First, H at a flow rate of 1 SLM ₂ Start introducing gas. Next, H at a flow rate of 0.4 SLM ₂ Start introducing O gas. After this, NH at a flow rate of 0.1 SLM _Three Start introducing gas.
[0079]
NH _Three The gas flow rate is not limited to 0.1 SLM, and may be set as appropriate within a range of 0.5 SLM or less, for example. H ₂ O gas and H ₂ The partial pressure ratio with the gas may be appropriately set under the condition that the silicon oxynitride film 24 can be formed on the side wall portion of the polysilicon film 14 without oxidizing the metal film 18 and the buffer film 16.
[0080]
In such an atmosphere, for example, when heat treatment is performed at 800 ° C. for 60 minutes, a silicon oxynitride film 24 is selectively formed on the side wall portion of the polysilicon film 14, and below the end portion of the gate electrode 20. A high nitrogen concentration region 30 is formed at the interface between the silicon substrate 10 and the gate insulating film 12, and a high nitrogen concentration region 32 is further formed at the interface between the polysilicon film 14 and the silicon oxynitride film 24.
[0081]
Next, N ₂ O gas, H ₂ Gas, H ₂ The introduction of O gas into the film formation chamber will be stopped sequentially.
[0082]
The subsequent processes are the same as those of the semiconductor device manufacturing method according to the first embodiment shown in FIG.
[0083]
Thus, NH as a nitrogen source _Three Even when a gas is used, a semiconductor device similar to that of the first embodiment shown in FIG. 1 can be manufactured.
[0084]
(Modification (Part 3))
A method of manufacturing a semiconductor device according to the modification (No. 3) of this embodiment will be described with reference to FIGS. FIG. 11 is a time chart showing a process for forming a silicon oxynitride film and a high nitrogen concentration region according to this modification.
[0085]
In the method of manufacturing the semiconductor device according to this modification, when the silicon oxynitride film 24 and the high nitrogen concentration regions 30 and 32 are formed, H ₂ The main feature is that no gas is introduced.
[0086]
First, the temperature in the deposition chamber is increased to 800 ° C., and N ₂ Since the process until the gas introduction is stopped is the same as that of the semiconductor device manufacturing method according to the first embodiment shown in FIG.
[0087]
Next, in the film formation chamber, NH _Three Gas, H ₂ O gas will be introduced sequentially. First, NH at a flow rate of 0.1 SLM _Three Start introducing gas. Next, H at a flow rate of 0.4 SLM ₂ Start introducing O gas. NH _Three Nitrogen contained in the gas functions as a nitrogen supply source when the silicon oxynitride film 24 and the high nitrogen concentration regions 30 and 32 are formed. _Three Hydrogen contained in the gas functions as a reducing gas that prevents oxidation of the metal film 18 and the buffer film 16.
[0088]
NH _Three The flow rate of the gas is not limited to 0.1 SLM, and can be appropriately set within a range of 0.05 to 0.2 SLM, for example. NH _Three Gas and H ₂ The partial pressure ratio with the O gas can be appropriately set within a range of, for example, 1: 4 to 1: 1.
[0089]
In such an atmosphere, for example, when heat treatment is performed at 800 ° C. for 60 minutes, a silicon oxynitride film 24 is selectively formed on the side wall portion of the polysilicon film 14, and also below the end of the gate electrode 20. A high nitrogen concentration region 30 is formed at the interface between the silicon substrate 10 and the gate insulating film 12, and a high nitrogen concentration region 32 is further formed at the interface between the polysilicon film 14 and the silicon oxynitride film 24.
[0090]
Next, H ₂ O gas, NH _Three The introduction of gas into the film formation chamber will be stopped sequentially.
[0091]
The subsequent processes are the same as those of the semiconductor device manufacturing method according to the first embodiment shown in FIG.
[0092]
According to this variation, NH _Three Since hydrogen contained in the metal functions as a reducing gas that prevents oxidation of the metal film 18 and the buffer film 16, ₂ Even when no gas is introduced, a semiconductor device similar to that of the first embodiment shown in FIG. 1 can be manufactured.
[0093]
(Modification (Part 4))
A method of manufacturing a semiconductor device according to the modification (No. 4) of this embodiment will be described with reference to FIGS. FIG. 12 is a time chart showing the formation process of the silicon oxynitride film and the high nitrogen concentration region according to this modification.
[0094]
In the manufacturing method of the semiconductor device according to the present modification, when the silicon oxynitride film 24 and the nitrogen high concentration regions 30 and 32 are formed, N ₂ The main feature is to use an atmosphere diluted with gas.
[0095]
First, N ₂ Since the process from stopping the introduction of gas to evacuating the film forming chamber is the same as that of the semiconductor device manufacturing method according to the first embodiment shown in FIG.
[0096]
Next, N at a flow rate of 5 SLM in the deposition chamber. ₂ Start introducing gas. N ₂ The gas functions as a dilution gas.
[0097]
Next, N ₂ H without stopping the introduction of gas ₂ Gas, H ₂ O gas and NO gas will be introduced sequentially. First, H at a flow rate of 1 SLM ₂ Start introducing gas. Next, H at a flow rate of 0.4 SLM ₂ Start introducing O gas. Next, introduction of NO gas is started at a flow rate of 0.5 SLM, and the pressure in the film formation chamber is set to, for example, about 26.7 kPa.
[0098]
Note that the flow rate of NO gas is not limited to 1 SLM, and may be set as appropriate within a range of 1 SLM or less, for example. H ₂ O gas and H ₂ The partial pressure ratio with the gas may be set as appropriate under the condition that the silicon nitride oxide film 24 can be selectively formed on the side wall portion of the polysilicon film 14 without oxidizing the W film and the buffer film. H ₂ O gas and H ₂ The partial pressure ratio between the gas and the NO gas can be appropriately set, for example, in the range of 2: 1 to 5: 1.
[0099]
In such an atmosphere, for example, when heat treatment is performed at 800 ° C. for 60 minutes, a silicon oxynitride film 24 is selectively formed on the side wall portion of the polysilicon film 14, and below the end portion of the gate electrode 20. A high nitrogen concentration region 30 is formed at the interface between the silicon substrate 10 and the gate insulating film 12, and a high nitrogen concentration region 32 is further formed at the interface between the polysilicon film 14 and the silicon oxynitride film 24.
[0100]
Next, NO gas, H ₂ O gas, H ₂ The introduction of gas into the film formation chamber will be stopped sequentially.
[0101]
The subsequent processes are the same as those of the semiconductor device manufacturing method according to the first embodiment shown in FIG.
[0102]
N as in this variation ₂ Even when an atmosphere diluted with gas is used, a semiconductor device similar to the semiconductor device according to the first embodiment shown in FIG. 1 can be manufactured.
[0103]
(Modification (Part 5))
A method for manufacturing a semiconductor device according to a modification (No. 5) of this embodiment will be described with reference to FIGS. FIG. 13 is a time chart showing the formation process of the silicon oxynitride film and the high nitrogen concentration region according to this modification.
[0104]
The semiconductor device manufacturing method according to this modification is mainly characterized in that an atmosphere diluted with Ar gas is used when the silicon oxynitride film 24 and the nitrogen high concentration regions 30 and 32 are formed.
[0105]
First, N ₂ Since the process from stopping the introduction of gas to evacuating the film forming chamber is the same as that of the semiconductor device manufacturing method according to the first embodiment shown in FIG.
[0106]
Next, introduction of Ar gas is started at a flow rate of 5 SLM in the deposition chamber. Ar gas functions as a dilution gas.
[0107]
Next, N ₂ H without stopping the introduction of gas ₂ Gas, H ₂ O gas and NO gas will be introduced sequentially. Specifically, first, at a flow rate of 1 SLM, H ₂ Start introducing gas. Next, H at a flow rate of 0.4 SLM ₂ Start introducing O gas. Next, introduction of NO gas is started at a flow rate of 0.5 SLM, and the pressure in the film formation chamber is set to, for example, about 26.7 kPa.
[0108]
Note that the flow rate of NO gas is not limited to 1 SLM, and may be set as appropriate within a range of 1 SLM or less, for example. H ₂ O and H ₂ May be set as appropriate under the condition that the silicon oxynitride film 24 can be selectively formed on the side wall portion of the polysilicon film 14 without oxidizing the metal film 18 and the buffer film 16. H ₂ O gas and H ₂ The partial pressure ratio between the gas and the NO gas can be appropriately set within a range of, for example, 4: 10: 1 to 4: 10: 5.
[0109]
In such an atmosphere, for example, when heat treatment is performed at 800 ° C. for 60 minutes, a silicon oxynitride film 24 is selectively formed on the side wall portion of the polysilicon film 14, and below the end portion of the gate electrode 20. A high nitrogen concentration region 30 is formed at the interface between the silicon substrate 10 and the gate insulating film 12, and a high nitrogen concentration region 32 is further formed at the interface between the polysilicon film 14 and the silicon oxynitride film 24.
[0110]
Next, NO gas, H ₂ O gas, H ₂ The introduction of gas into the film formation chamber will be stopped sequentially.
[0111]
Next, the introduction of Ar gas into the deposition chamber is stopped.
[0112]
The subsequent processes are the same as those of the semiconductor device manufacturing method according to the first embodiment shown in FIG.
[0113]
Even in the case where an atmosphere diluted with Ar gas is used as in this modification, a semiconductor device similar to the semiconductor device according to the first embodiment shown in FIG. 1 can be manufactured.
[0114]
[Second Embodiment]
A semiconductor device and a manufacturing method thereof according to the second embodiment of the present invention will be described with reference to FIGS. FIG. 14 is a sectional view of the semiconductor device according to the present embodiment. FIG. 15 is a process cross-sectional view illustrating the semiconductor device manufacturing method according to the present embodiment. FIG. 16 is a time chart showing the formation process of the silicon oxynitride film and the high nitrogen concentration region according to the present embodiment. The same components as those of the semiconductor device and the manufacturing method thereof according to the first embodiment shown in FIGS. 1 to 13 are denoted by the same reference numerals, and description thereof will be omitted or simplified.
[0115]
First, the semiconductor device according to the present embodiment will be explained with reference to FIG.
[0116]
As shown in FIG. 14, a silicon oxynitride film 24 a is formed on the side wall portion of the polysilicon film 14. The silicon oxynitride film 24a is substantially the same as the silicon oxynitride film 24 of the semiconductor device according to the first embodiment, and can be formed by a method described later.
[0117]
The other components are the same as those of the semiconductor device according to the first embodiment shown in FIG.
[0118]
Next, the method for fabricating the semiconductor device according to the present embodiment will be explained with reference to FIGS.
[0119]
The semiconductor device manufacturing method according to the present embodiment is mainly characterized in that after a silicon oxide film is selectively formed on the side wall portion of the polysilicon film, a high nitrogen concentration region is formed.
[0120]
First, the steps until the gate electrode 20 is formed are the same as those in the semiconductor device manufacturing method according to the first embodiment shown in FIGS.
[0121]
Next, as shown in FIG. 15A, a silicon oxide film 23 is selectively formed on the side wall portion of the polysilicon film 14 without oxidizing the metal film 18 and the buffer film 16. Such a silicon oxide film 23 can be formed by a process as shown in FIG.
[0122]
First, N ₂ Since the process from stopping the introduction of gas to evacuating the film forming chamber is the same as that of the semiconductor device manufacturing method according to the first embodiment shown in FIG.
[0123]
Next, as shown in FIG. ₂ Gas, H ₂ O gas will be introduced sequentially. First, H at a flow rate of 1 SLM ₂ Start introducing gas. Next, H at a flow rate of 0.4 SLM ₂ O gas introduction is started and the pressure in the film forming chamber is set to 4 kPa, for example.
[0124]
H ₂ O and H ₂ May be set as appropriate under the condition that the silicon oxynitride film 24 can be selectively formed on the side wall portion of the polysilicon film 14 without oxidizing the metal film 18 and the buffer film 16.
[0125]
Then, the temperature in the deposition chamber is increased to 800 ° C. When heat treatment is performed at 800 ° C. for 60 minutes in such an atmosphere, a silicon oxide film 23 is selectively formed on the side wall portion of the polysilicon film 14.
[0126]
Next, H ₂ The introduction of O gas into the deposition chamber is completed.
[0127]
Next, H ₂ The introduction of NO gas is started at a flow rate of 1 SLM without ending the introduction of the gas into the film formation chamber. When heat treatment is performed at 800 ° C. for 30 minutes in such an atmosphere, nitrogen is introduced into the silicon oxide film 23 to form the silicon oxynitride film 24a, and between the polysilicon film 14 and the silicon oxynitride film 24a. A high nitrogen concentration region 32 is formed at the interface, and a high nitrogen concentration region 30 is formed at the interface between the silicon substrate 10 and the gate insulating film 12 below the end of the gate electrode 20 (FIG. 15B). )reference).
[0128]
NO gas and H ₂ The partial pressure ratio with the gas can be appropriately set within a range of 1: 1 to 0.2: 1, for example.
[0129]
The subsequent manufacturing method of the semiconductor device according to the present embodiment is the same as the manufacturing method of the semiconductor device according to the first embodiment shown in FIGS.
[0130]
As described above, even when the silicon high-concentration regions 30 and 32 are formed after the silicon oxide film 23 is selectively formed on the side wall portion of the polysilicon film 14, the same as in the first embodiment shown in FIG. A semiconductor device can be manufactured.
[0131]
(Modification (Part 1))
A method of manufacturing a semiconductor device according to the first modification of the embodiment will be described with reference to FIGS. FIG. 17 is a time chart showing a process for forming a silicon oxynitride film and a high nitrogen concentration region according to this modification.
[0132]
The manufacturing method of the semiconductor device according to this modification is NH _Three The main features are that nitrogen is introduced into the silicon oxide film 23 and the nitrogen high concentration regions 30 and 32 are formed using an atmosphere made of gas.
[0133]
First, in the film formation chamber, H ₂ Gas and H ₂ The process up to introducing the O gas and selectively forming the silicon oxide film 23 on the side wall portion of the polysilicon film 14 is the same as the method of manufacturing the semiconductor device according to the second embodiment shown in FIG. Omitted.
[0134]
Next, as shown in FIG. ₂ The introduction of O gas is terminated, and H ₂ Finish the gas introduction.
[0135]
Next, NH at a flow rate of 0.1 SLM _Three Start introducing gas. When heat treatment is performed at 800 ° C. for 30 minutes in such an atmosphere, nitrogen is introduced into the silicon oxide film 23 to form the silicon oxynitride film 24a, and between the polysilicon film 14 and the silicon oxynitride film 24a. A high nitrogen concentration region 32 is formed at the interface, and a high nitrogen concentration region 30 is formed at the interface between the silicon substrate 10 and the gate insulating film 12 below the end of the gate electrode 20.
Next, NH into the film formation chamber _Three Finish the gas introduction.
[0136]
The subsequent processes are the same as those of the semiconductor device manufacturing method according to the second embodiment shown in FIG.
[0137]
In this way NH _Three Even when an atmosphere made of a gas is used, nitrogen can be introduced into the silicon oxide film 23 to form the silicon oxynitride film 24a, and the nitrogen high concentration regions 30 and 32 can be formed. Therefore, according to this modification, a semiconductor device similar to the semiconductor device according to the second embodiment shown in FIG. 14 can be manufactured.
[0138]
(Modification (Part 2))
A method for manufacturing a semiconductor device according to a modification (No. 2) of this embodiment will be described with reference to FIGS. FIG. 18 is a time chart showing the formation process of the silicon oxynitride film and the high nitrogen concentration region according to this modification.
[0139]
The manufacturing method of the semiconductor device according to the present modification includes NO gas and NH. _Three The main characteristics are that nitrogen is introduced into the silicon oxide film 23 using an atmosphere composed of gas and the nitrogen high concentration regions 30 and 32 are formed.
[0140]
First, in the film formation chamber, H ₂ Gas and H ₂ The process up to the process of introducing the O gas and selectively forming the silicon oxide film 23 on the side wall portion of the polysilicon film 14 is the same as the method of manufacturing the semiconductor device according to the second embodiment shown in FIG. To do.
[0141]
Next, as shown in FIG. ₂ After the introduction of O gas was completed, H ₂ Finish the gas introduction.
[0142]
Next, NH at a flow rate of 0.1 SLM _Three Start introducing gas. Thereafter, introduction of NO gas is started at a flow rate of 0.5 SLM. When heat treatment is performed at 800 ° C. for 30 minutes in such an atmosphere, nitrogen is introduced into the silicon oxide film 23 to form the silicon nitride oxide film 24a, and the interface between the polysilicon film 14 and the silicon nitride oxide film 24a. Then, a high nitrogen concentration region 32 is formed, and a high nitrogen concentration region 30 is formed at the interface between the silicon substrate 10 and the gate insulating film 12 below the end of the gate electrode 20.
[0143]
NO gas and NH _Three The partial pressure ratio with the gas can be appropriately set within a range of 1: 1 to 5: 1, for example.
[0144]
Next, the introduction of NO gas is terminated, and then NH _Three Finish the gas introduction.
[0145]
The subsequent processes are the same as those of the semiconductor device manufacturing method according to the second embodiment shown in FIG.
[0146]
In this way, NO gas and NH _Three Even when an atmosphere composed of gas is used, nitrogen can be introduced into the silicon oxide film 23 to form the silicon oxynitride film 24a, and the nitrogen high concentration regions 30 and 32 can be formed. . Therefore, according to this modification, a semiconductor device similar to the semiconductor device according to the second embodiment shown in FIG. 14 can be manufactured.
[0147]
(Modification (Part 3))
A method for manufacturing a semiconductor device according to a modification (No. 3) of the present embodiment will be described with reference to FIGS. FIG. 19 is a time chart showing the formation process of the silicon oxynitride film and the high nitrogen concentration region according to this modification.
[0148]
A manufacturing method of a semiconductor device according to this modification is N ₂ O gas and H ₂ The main characteristics are that nitrogen is introduced into the silicon oxide film 23 using an atmosphere composed of gas and the nitrogen high concentration regions 30 and 32 are formed.
[0149]
First, in the film formation chamber, H ₂ Gas and H ₂ The process up to the step of selectively forming the silicon oxide film 23 on the side wall portion of the polysilicon film 14 by introducing O gas is the same as the method of manufacturing the semiconductor device according to the second embodiment shown in FIG. To do.
[0150]
Next, as shown in FIG. ₂ H without stopping the introduction of gas ₂ The introduction of O gas into the deposition chamber is completed.
[0151]
Next, N at a flow rate of 5 SLM ₂ Start introducing O gas. When heat treatment is performed at 800 ° C. for 30 minutes in such an atmosphere, nitrogen is introduced into the silicon oxide film 23 to form the silicon nitride oxide film 24a, and the interface between the polysilicon film 14 and the silicon nitride oxide film 24a. Then, a high nitrogen concentration region 32 is formed, and a high nitrogen concentration region 30 is formed at the interface between the silicon substrate 10 and the gate insulating film 12 below the end of the gate electrode 20.
[0152]
H ₂ Gas and N ₂ The partial pressure ratio with O gas can be set as appropriate within a range of 1: 1 to 1: 5, for example.
[0153]
Next, N ₂ After the introduction of O gas was completed, H ₂ Finish the gas introduction.
[0154]
The subsequent processes are the same as those of the semiconductor device manufacturing method according to the second embodiment shown in FIG.
[0155]
N like this ₂ O gas and H ₂ Even when an atmosphere composed of gas is used, nitrogen can be introduced into the silicon oxide film 23 to form the silicon oxynitride film 24a, and the nitrogen high concentration regions 30 and 32 can be formed. . Therefore, according to this modification, a semiconductor device similar to the semiconductor device according to the second embodiment shown in FIG. 14 can be manufactured.
[0156]
(Modification (Part 4))
A method of manufacturing a semiconductor device according to the modification (No. 4) of this embodiment will be described with reference to FIGS. FIG. 20 is a time chart showing a process for forming a silicon oxynitride film and a high nitrogen concentration region according to this modification.
[0157]
A manufacturing method of a semiconductor device according to this modification is N ₂ O gas and NH _Three The main characteristics are that nitrogen is introduced into the silicon oxide film 23 using an atmosphere composed of gas and the nitrogen high concentration regions 30 and 32 are formed.
[0158]
First, in the film formation chamber, H ₂ Gas, H ₂ The process up to the step of selectively forming the silicon oxide film 23 on the side wall portion of the polysilicon film 14 by introducing O gas is the same as the method of manufacturing the semiconductor device according to the second embodiment shown in FIG. To do.
[0159]
Next, as shown in FIG. ₂ After the introduction of O gas was completed, H ₂ Finish the gas introduction.
[0160]
Next, NH at a flow rate of 0.1 SLM _Three Start introducing gas. After this, N at a flow rate of 5 SLM ₂ Start introducing O gas. When heat treatment is performed at 800 ° C. for 30 minutes in such an atmosphere, nitrogen is introduced into the silicon oxide film 23 to form the silicon nitride oxide film 24a, and the interface between the polysilicon film 14 and the silicon nitride oxide film 24a. Then, a high nitrogen concentration region 32 is formed, and a high nitrogen concentration region 30 is formed at the interface between the silicon substrate 10 and the gate insulating film 12 below the end of the gate electrode 20.
[0161]
NH _Three Gas and N ₂ The partial pressure ratio with O gas can be appropriately set within a range of, for example, 1:10 to 1:50.
[0162]
Next, N ₂ After the introduction of O gas, NH _Three Finish the gas introduction.
[0163]
The subsequent processes are the same as those of the semiconductor device manufacturing method according to the second embodiment shown in FIG.
[0164]
N like this ₂ O gas and NH _Three Even when an atmosphere composed of gas is used, nitrogen can be introduced into the silicon oxide film 23 to form the silicon oxynitride film 24a, and the nitrogen high concentration regions 30 and 32 can be formed. . Therefore, according to this modification, a semiconductor device similar to the semiconductor device according to the second embodiment shown in FIG. 14 can be manufactured.
[0165]
(Modification (Part 5))
A method for manufacturing a semiconductor device according to the modification (No. 5) of the present embodiment will be described with reference to FIGS. FIG. 21 is a time chart showing a process for forming a silicon oxynitride film and a high nitrogen concentration region according to this modification.
[0166]
A manufacturing method of a semiconductor device according to this modification is N ₂ The main characteristics are that nitrogen is introduced into the silicon oxide film 23 using an atmosphere diluted with gas and the nitrogen high concentration regions 30 and 32 are formed.
[0167]
First, N ₂ Since the process from stopping the introduction of gas to evacuating the film forming chamber is the same as that of the method for manufacturing the semiconductor device according to the second embodiment shown in FIG.
[0168]
Next, as shown in FIG. 21, N is flown into the film forming chamber at a flow rate of 5 SLM. ₂ Start introducing gas. N ₂ The gas functions as a dilution gas.
[0169]
Next, N ₂ H without stopping the introduction of gas ₂ Gas, H ₂ O gas is introduced sequentially. Specifically, first, at a flow rate of 1 SLM, H ₂ Start introducing gas. Next, H at a flow rate of 0.4 SLM ₂ O gas introduction is started, and the pressure in the film formation chamber is set to, for example, about 26.7 kPa.
[0170]
When heat treatment is performed at 800 ° C. for 60 minutes in such an atmosphere, a silicon oxide film 23 is selectively formed on the side wall portion of the polysilicon film 14.
[0171]
Next, H ₂ Gas and N ₂ H without stopping the introduction of gas ₂ The introduction of O gas is terminated.
[0172]
Next, introduction of NO gas is started at a flow rate of 1 SLM. When heat treatment is performed at 800 ° C. for 30 minutes in such an atmosphere, nitrogen is introduced into the silicon oxide film 23 to form a silicon oxynitride film 24a, and the polysilicon film 14 and the silicon oxynitride film 24a A high nitrogen concentration region 32 is formed at the interface, and a high nitrogen concentration region 30 is formed at the interface between the silicon substrate 10 and the gate insulating film 12 below the end of the gate electrode 20.
[0173]
NO gas and H ₂ Gas and N ₂ The partial pressure ratio with the gas can be appropriately set within a range of 0.2: 1: 5 to 1: 1: 5, for example.
[0174]
Next, the introduction of NO gas is terminated, and then H ₂ Finish the gas introduction. In addition, N ₂ Finish the gas introduction.
[0175]
The subsequent processes are the same as those of the semiconductor device manufacturing method according to the second embodiment shown in FIG.
[0176]
N as in this variation ₂ Even when an atmosphere diluted with a gas is used, nitrogen can be introduced into the silicon oxide film 23 to form the silicon oxynitride film 24a, and the nitrogen high concentration regions 30 and 32 can be formed. . Therefore, according to this modification, a semiconductor device similar to the semiconductor device according to the second embodiment shown in FIG. 14 can be manufactured.
[0177]
(Modification (Part 6))
A method for manufacturing a semiconductor device according to a modification (No. 6) of this embodiment will be described with reference to FIGS. FIG. 22 is a time chart showing the formation process of the silicon oxynitride film and the high nitrogen concentration region according to this modification.
[0178]
The manufacturing method of the semiconductor device according to this modification is mainly characterized in that nitrogen is introduced into the silicon oxide film 23 in an atmosphere diluted with Ar gas and the nitrogen high concentration regions 30 and 32 are formed. .
[0179]
First, N ₂ Since the process from stopping the introduction of gas to evacuating the film forming chamber is the same as that of the method for manufacturing the semiconductor device according to the second embodiment shown in FIG.
[0180]
Next, introduction of Ar gas is started at a flow rate of 5 SLM in the deposition chamber. Ar gas functions as a dilution gas.
[0181]
Next, without stopping the introduction of Ar gas, H ₂ Gas, H ₂ O gas will be introduced sequentially. Specifically, first, at a flow rate of 1 SLM, H ₂ Start introducing gas. Next, H at a flow rate of 0.4 SLM ₂ O gas introduction is started, and the pressure in the film formation chamber is set to, for example, about 26.7 kPa.
[0182]
When heat treatment is performed at 800 ° C. for 60 minutes in such an atmosphere, a silicon oxide film 23 is selectively formed on the side wall portion of the polysilicon film 14.
[0183]
Next, H ₂ Gas and N ₂ H without stopping the introduction of gas ₂ The introduction of O gas is terminated.
[0184]
Next, introduction of NO gas is started at a flow rate of 1 SLM. When heat treatment is performed at 800 ° C. for 30 minutes in such an atmosphere, nitrogen is introduced into the silicon oxide film 23 to form a silicon oxynitride film 24a, and the polysilicon film 14 and the silicon oxynitride film 24a A high nitrogen concentration region 32 is formed at the interface, and a high nitrogen concentration region 30 is formed at the interface between the silicon substrate 10 and the gate insulating film 12 below the end of the gate electrode 20.
[0185]
NO gas and H ₂ The partial pressure ratio between the gas and the Ar gas can be appropriately set within a range of 0.2: 1: 5 to 1: 1: 5, for example.
[0186]
Next, the introduction of NO gas is terminated, and then H ₂ Finish the gas introduction. Further, the introduction of Ar gas is terminated.
[0187]
The subsequent processes are the same as those of the semiconductor device manufacturing method according to the second embodiment shown in FIG.
[0188]
Even in the case where an atmosphere diluted with Ar gas is used as in this modification, the silicon oxynitride film 24a can be formed by introducing nitrogen into the silicon oxide film 23, and the nitrogen high concentration region 30, 32 can be formed. Therefore, according to this modification, a semiconductor device similar to the semiconductor device according to the second embodiment shown in FIG. 14 can be manufactured.
[0189]
[Modified Embodiment]
The present invention is not limited to the above embodiment, and various modifications can be made.
[0190]
For example, in the first or second embodiment, the temperature in the film formation chamber is set to 800 ° C. and the silicon oxynitride film and the high nitrogen concentration region are formed, but the temperature in the film formation chamber is not limited to 800 ° C. For example, the temperature in the deposition chamber may be appropriately set in the range of 700 ° C. to 1050 ° C., preferably in the range of 750 ° C. to 850 ° C.
[0191]
In the first modification to the first modification (No. 3), N ₂ You may dilute using gas or Ar gas.
[0192]
Further, in the modification (part 1) to the modification (part 4) of the second embodiment, N ₂ You may dilute using gas or Ar gas.
[0193]
In the first and second embodiments, N ₂ Although diluted with gas or Ar gas, the dilution gas is N ₂ It is not limited to gas or Ar gas, For example, you may dilute using noble gases, such as Xe gas and Kr gas.
[0194]
Further, the gas flow rate is not limited to the gas flow rate shown in the first and second embodiments, and the gas flow rate is appropriately set to form a desired silicon oxynitride film and a desired high nitrogen concentration region. May be.
[0195]
【The invention's effect】
As described above, according to the present invention, after patterning the gate electrode, heat treatment is performed in a gas atmosphere containing nitrogen atoms and having an oxidizing action and a reducing action. In addition to forming a nitrided oxide film, a high nitrogen concentration region can be formed at the interface between the polysilicon film and the silicon nitride oxide film. Since a high nitrogen concentration region is formed at the interface between the polysilicon film and the silicon oxynitride film, according to the present invention, depletion of the polysilicon film can be suppressed.
[0196]
In addition, according to the present invention, after patterning the gate electrode, heat treatment is performed in a gas atmosphere containing nitrogen atoms and having an oxidizing action and a reducing action. A high nitrogen concentration region can be formed at the interface with the film. Since a high nitrogen concentration region is formed at the interface between the silicon substrate and the gate insulating film, according to the present invention, a semiconductor device with good hot carrier resistance can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a semiconductor device according to a first embodiment of the present invention.
FIG. 2 is a graph showing a nitrogen concentration distribution in a region near an interface between a gate insulating film and a silicon substrate below an end portion of a gate electrode.
FIG. 3 is a process cross-sectional view (part 1) illustrating the method for manufacturing the semiconductor device according to the first embodiment of the invention;
FIG. 4 is a process cross-sectional view (part 2) illustrating the method for manufacturing the semiconductor device according to the first embodiment of the invention;
FIG. 5 is a process cross-sectional view (part 3) illustrating the method for manufacturing the semiconductor device according to the first embodiment of the present invention;
FIG. 6 is a process cross-sectional view (No. 4) illustrating the method for manufacturing the semiconductor device according to the first embodiment of the invention;
FIG. 7 is a time chart showing a formation process of the silicon oxynitride film and the high nitrogen concentration region according to the first embodiment of the present invention.
FIG. 8 is a graph showing the presence or absence of oxidation of silicon and tungsten.
FIG. 9 is a time chart showing a process of forming a silicon oxynitride film and a nitrogen high concentration region according to a modification (Part 1) of the first embodiment of the present invention.
FIG. 10 is a time chart showing a process for forming a silicon oxynitride film and a high nitrogen concentration region according to a modification (Part 2) of the first embodiment of the present invention.
FIG. 11 is a time chart showing a process for forming a silicon oxynitride film and a high nitrogen concentration region according to a modification (No. 3) of the first embodiment of the present invention.
12 is a time chart showing a process for forming a silicon oxynitride film and a high nitrogen concentration region according to a modification (No. 4) of the first embodiment of the present invention. FIG.
FIG. 13 is a time chart showing a process for forming a silicon oxynitride film and a high nitrogen concentration region according to a modification (No. 5) of the first embodiment of the present invention.
FIG. 14 is a cross-sectional view showing a semiconductor device according to a second embodiment of the present invention.
FIG. 15 is a process sectional view illustrating the method for producing the semiconductor device according to the second embodiment of the invention.
FIG. 16 is a time chart showing a process of forming a silicon oxynitride film and a high nitrogen concentration region according to the second embodiment of the present invention.
FIG. 17 is a time chart showing a process for forming a silicon oxynitride film and a high nitrogen concentration region according to a modification (Part 1) of the second embodiment of the present invention.
FIG. 18 is a time chart showing a process of forming a silicon oxynitride film and a high nitrogen concentration region according to a modification (No. 2) of the second embodiment of the present invention.
FIG. 19 is a time chart showing a process for forming a silicon oxynitride film and a high nitrogen concentration region according to a modification (No. 3) of the second embodiment of the present invention.
FIG. 20 is a time chart showing a formation process of a silicon oxynitride film and a high nitrogen concentration region according to a modification (No. 4) of the second embodiment of the present invention.
FIG. 21 is a time chart showing a formation process of a silicon oxynitride film and a high nitrogen concentration region according to a modification (No. 5) of the second embodiment of the present invention.
FIG. 22 is a time chart showing a formation process of a silicon oxynitride film and a high nitrogen concentration region according to a modification (No. 6) of the second embodiment of the present invention.
FIG. 23 is a cross-sectional view showing a proposed semiconductor device.
[Explanation of symbols]
10 ... Silicon substrate
12 ... Gate insulating film
14 ... Polysilicon film
16 ... Buffer film
18 ... Metal film
20 ... Gate electrode
22 ... Cap membrane
23 ... Silicon oxide film
24. Silicon oxynitride film
24a ... Silicon nitride oxide film
26. Sidewall insulating film
28 ... Source / drain diffusion layer
28a, 28b ... impurity diffusion regions
30 ... Nitrogen high concentration region
32 ... Nitrogen high concentration region
110: Silicon substrate
112 ... Gate insulating film
114 ... polysilicon film
116: Buffer film
118 ... Metal film
120 ... Gate electrode
122 ... Cap membrane
123 ... Silicon oxide film
126 ... sidewall insulating film
128: Source / drain diffusion layer
128a, 128b ... impurity diffusion regions
130: Nitrogen high concentration region

Claims (2)

Forming a gate insulating film on the silicon substrate;
Forming a gate electrode having a polysilicon film and a metal film formed on the polysilicon film on the gate insulating film;
A heat treatment is performed in a gas atmosphere containing nitrogen atoms and having an oxidizing action and a reducing action, and an insulating film is selectively formed on a side wall portion of the polysilicon film, and the silicon substrate below the end of the gate electrode And a step of introducing nitrogen into an interface between the gate insulating film and the gate insulating film. In the manufacturing method of the semiconductor device according to claim 1 ,
In the step of introducing nitrogen, nitrogen is also introduced into the interface between the polysilicon film and the insulating film.

Images