JP2004241444A - Method for manufacturing semiconductor device - Google Patents

Abstract

An object of the present invention is to prevent retreat of an isolation insulating film and retreat of a sidewall caused by wet etching of an insulating film for forming a non-silicide region.
A first step of exposing the A surface of the polysilicon film and the silicon substrate surface, a second step of resist patterning, and at the same time to remove the resist film 5 by carrying out the O ₂ ashing, no resist film 5 is present a third step of forming a polysilicon film surface and the silicon substrate surface by O ₂ ashing oxide silicide formation preventing oxide film 8 exposed regions, the heat treatment after depositing a refractory metal film 6 on the silicon substrate 1 Performing a fourth step of silicidizing the surface of the polysilicon film and the surface of the silicon substrate in a region where the silicide formation preventing oxide film 8 does not exist to form the refractory metal silicide layer 7; A fifth step of removing the refractory metal film 6.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a semiconductor device having a MOS transistor.
[0002]
[Prior art]
In recent years, in the manufacturing process of an LSI including a MOS transistor, miniaturization of the MOS transistor has been increasingly demanded in order to achieve higher speed and higher integration of the LSI.
[0003]
In order to advance the miniaturization of the MOS transistor, it is necessary not only to reduce the respective dimensions of the gate length and the gate width of the transistor but also to make the junction surface of the source / drain diffusion layer shallower.
[0004]
On the other hand, it is necessary to compensate for the increase in the sheet resistance of the gate electrode due to the reduction in the gate length and the increase in the sheet resistance of the diffusion layer due to the reduction in the size of the source / drain diffusion layer and the shallow junction. In recent years, a silicide process for silicidizing the upper part of the gate electrode and the surface of the source / drain diffusion layer has been frequently used to cope with these problems. In the silicide process, a high melting point metal (for example, Co, Ti, Ni) is deposited by sputtering on the upper portion of a gate electrode formed of polysilicon and the surface of silicon as a source / drain diffusion layer. Thus, polysilicon is formed above the gate electrode, and silicon and the refractory metal film are reacted on the surface of the source / drain diffusion layer to form a silicide layer to reduce the resistance.
[0005]
On the other hand, in the I / O circuit portion of the LSI, conversely, it is required to increase the gate, source and drain resistances in order to prevent electrostatic breakdown. There is also a demand for a high resistance part in an analog circuit. Therefore, the gate and the source / drain portion of the LSI are mostly silicided, but the transistors and resistors of the I / O portion or a part of the analog circuit are used without silicidation. That is, there is a need for a method of manufacturing a semiconductor device that does not silicide a gate polysilicon or a source / drain region used as a gate electrode or a source / drain electrode of a transistor or a resistor of an analog circuit. This is called non-silicidation.
[0006]
As a method of forming a semiconductor device for forming a non-silicide region, the following conventional method is generally used.
[0007]
FIG. 5 shows a cross-sectional view of a conventional semiconductor device.
[0008]
In FIG. 5, reference numeral 1 denotes a silicon substrate. 2 is an isolation insulating film. Reference numeral 3 denotes a diffusion layer into which ions are implanted, and forms a source and a drain. Reference numeral 4 denotes an insulating film for non-silicide formation. Reference numeral 5 denotes a resist for forming a non-silicide region. Reference numeral 6 denotes a high melting point metal film used for forming silicide. 7 is a silicide film.
[0009]
Next, a method for manufacturing the semiconductor device of FIG. 5 will be described.
[0010]
In FIG. 5 (a), after an isolation insulating film 2 for electrically isolating elements such as transistors is formed on a silicon substrate 1, a gate insulating film and a gate electrode are formed, and injection diffusion of a source / drain portion is performed. This is a state where the layer 3 is formed. In (a), the gate electrode and the like of the transistor are omitted in the drawing. (B) shows a state in which an insulating film 4 for forming non-silicide is deposited by a CVD method. (C) shows a state where a resist 5 for forming a non-silicide region is applied and patterned. The opening of the resist 5 is silicided, and is patterned so as to be a non-silicide portion where the resist 5 exists. (D) shows a state in which the insulating film 4 for non-silicide formation has been wet-etched using a diluted hydrofluoric acid solution or a BHF solution using the resist 5 as a mask. (E) shows a state in which the resist is removed and the high melting point metal film 6 is deposited. As the refractory metal film 6, a Co, Ti, Ni film or the like is used. (F) is a heat treatment using RTA or the like for silicide formation, and silicidation is performed at a place where the silicon film 1 and the refractory metal film 6 are in contact with each other. In this state, the refractory metal film 6 on the insulating film such as the forming insulating film 4 is selectively wet-etched and removed, leaving only the silicide film 7 that has undergone silicidation. With the above forming method, a silicide region and a non-silicide region can be formed.
[0011]
As a conventional example, there is a method of performing thermal treatment for a short time after ion-implanting the non-silicide forming insulating film 4 for forming a source / drain diffusion layer as described in Patent Document 1, and forming a thermal oxide film. In this method, an oxide film formed by using rapid thermal oxidation instead of the CVD insulating film 4 is used as the non-silicide forming insulating film 4.
[0012]
[Patent Document 1]
JP-A-11-145080
[0013]
[Problems to be solved by the invention]
The conventional method for manufacturing a semiconductor device configured as described above has the following problems.
[0014]
In the conventional example, wet etching is performed when the non-silicide-forming insulating film 4 is etched, so that there is a problem that the isolation insulating film 2 is retreated due to over-etching and the sidewall of the transistor is retreated. This retreat causes a problem of an increase in junction leak current due to silicide formation. In particular, in recent semiconductor devices, since the miniaturization is progressing, the junction of the source and the drain is becoming shallower, and a junction leak is likely to occur in later silicide formation. In addition, the isolation oxide film also has a shallow trench isolation (STI), which causes a problem of junction leakage at the STI edge. Since the greatest problem is that the junction leak is particularly likely to occur at the STI edge portion due to the retreat of the STI by the wet etching, the retreat of the STI due to the wet etching must be avoided as much as possible.
[0015]
On the other hand, even if wet etching is changed to dry etching in order to avoid regression of STI, an etching residue peculiar to dry etching is generated, and a portion that is not silicided is generated, which causes a reduction in yield. In addition, the silicon surface is damaged by dry etching, impurities, and the like, so that silicidation is inhibited.
[0016]
Therefore, it is desirable to etch the non-silicide forming insulating film by wet etching before silicidation. However, it is necessary to control the recession of the isolation insulating film 2 and the recession of the sidewall of the transistor as in the above-described conventional example. It has become.
[0017]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method of manufacturing a semiconductor device which prevents a recession of an isolation insulating film or a sidewall caused by wet etching of a silicidation preventing insulating film for forming a non-silicide region. It is.
[0018]
[Means for Solving the Problems]
In order to achieve the above object, a method of manufacturing a semiconductor device according to claim 1 of the present invention is directed to a MOS device having a gate electrode made of a polysilicon film on a silicon substrate on which an isolation insulating film and a gate insulating film are formed. A method of manufacturing a semiconductor device for forming a transistor, comprising: removing an insulating film remaining on an upper portion of the silicon substrate to be an upper portion of the gate electrode and a source / drain region to expose a surface of the polysilicon film and a surface of the silicon substrate. One step, a second step of applying a resist film for forming a non-silicide region on the silicon substrate and patterning the resist, ₂ The ashing is performed to remove the resist film, and at the same time, the exposed surface of the polysilicon film and the surface of the silicon substrate in the region where the resist film is not present are covered with O. ₂ A third step of forming an oxide film for preventing silicide formation by ashing oxidation, and performing a heat treatment after depositing a refractory metal film on the silicon substrate to form a polycrystalline silicon film in a region where the silicide formation preventing oxide film does not exist. A fourth step of forming a refractory metal silicide layer by silicidizing the surface of the silicon film and the surface of the silicon substrate to form a refractory metal silicide layer; and a fifth step of removing the refractory metal film on the silicide formation preventing oxide film.
[0019]
Thus, a step of applying a resist film for forming a non-silicide region on a silicon substrate and patterning the resist, ₂ The resist film is removed by ashing, and at the same time, the surface of the exposed polysilicon film and the surface of the silicon substrate in the region where no resist film is present are treated with O.sub.2. ₂ Ashing oxidation to form a silicide formation preventing oxide film, and heat treatment after depositing a refractory metal film on a silicon substrate to form a polysilicon film surface and silicon in a region where the silicide formation preventing oxide film does not exist. Since the method includes the steps of silicidizing the substrate surface to form a refractory metal silicide layer and the step of removing the refractory metal film on the silicide formation preventing oxide film, a non-silicide formation insulating film is formed as in the conventional example. It is not necessary to form a pattern by wet etching. That is, instead of etching the non-silicide forming insulating film by wet etching, O ₂ By oxidizing a portion having no resist by ashing, an insulating film for forming a non-silicide can be formed without wet etching. For this reason, it is possible to prevent the separation insulating film from receding due to overetching when the non-silicide forming insulating film is wet-etched, and the sidewall of the transistor from receding.
[0020]
The method of manufacturing a semiconductor device according to claim 2, wherein in the method of manufacturing a semiconductor device according to claim 1, the thickness of the oxide film for preventing silicide formation in the third step is the thickness of the oxide film in the region where the resist film was present. Thicker than As described above, in the third step, the thickness of the oxide film for preventing silicide formation is thicker than the thickness of the oxide film in the region where the resist film was present. Even if a film is formed, a silicide region and a non-silicide region can be formed by forming the region where the resist film is not present to have a larger oxide film thickness than the oxide film thickness.
[0021]
According to a third aspect of the present invention, in the method of manufacturing a semiconductor device according to the first aspect, after the second step, the surface of the polysilicon film and the surface of the silicon substrate exposed by implanting silicon ions are made amorphous. Including the step of forming As described above, after the second step, a step of implanting silicon ions and amorphizing the exposed polysilicon film surface and the silicon substrate surface is included. ₂ Reaction with plasma is promoted, and a thicker oxide film is formed.
[0022]
According to a fourth aspect of the present invention, there is provided a method of manufacturing a semiconductor device according to the first, second, or third aspect, further comprising: ₂ Plasma density is 1E11 / cm ³ Above and O ₂ O under the condition that ion energy is 100 eV or more ₂ Perform ashing. Thus, in the third step, O ₂ Plasma density is 1E11 / cm ³ Above and O ₂ O under the condition that ion energy is 100 eV or more ₂ Oxidizing O ₂ Ashing can be performed.
[0023]
A method of manufacturing a semiconductor device according to claim 5, wherein a MOS transistor having a gate electrode made of a polysilicon film is formed on a silicon substrate on which an isolation insulating film and a gate insulating film are formed. A first step of removing an insulating film remaining on the silicon substrate to be an upper part of the gate electrode and the source / drain region to expose the polysilicon film surface and the silicon substrate surface; and a non-silicide region on the silicon substrate. A second step of applying a resist film for forming and patterning the resist, and implanting oxygen ions or nitrogen ions using the resist film as a mask to form a polysilicon film surface and the silicon substrate in a region where the resist film does not exist; A third step of introducing oxygen ions or nitrogen ions to the surface; Performing a first heat treatment after depositing a refractory metal film on the silicon substrate to remove the polysilicon film surface and the silicon substrate surface in a region other than the ion-implanted region. A fifth step of forming a refractory metal silicide layer by silicidation and a sixth step of removing the refractory metal film on the ion-implanted region that has not been silicided are included.
[0024]
Thus, a step of applying a resist film for forming a non-silicide region on a silicon substrate and patterning the resist, and implanting oxygen ions or nitrogen ions using the resist film as a mask to form a polysilicon in a region where the resist film does not exist A step of introducing oxygen ions or nitrogen ions into the film surface and the silicon substrate surface; a step of removing the resist film; The method includes the steps of silicidizing the surface of the polysilicon film and the silicon substrate in the region of the region to form a refractory metal silicide layer, and removing the refractory metal film on the non-silicided ion-implanted region. It is possible to pattern the insulating film for non-silicide formation by wet etching as in The cornerstone. That is, the non-silicide-forming insulating film can be formed without wet etching by injecting oxygen or nitrogen instead of etching the non-silicide-forming insulating film by wet etching. For this reason, it is possible to prevent the separation insulating film from receding due to overetching when the non-silicide forming insulating film is wet-etched, and the sidewall of the transistor from receding.
[0025]
According to a sixth aspect of the present invention, in the method of manufacturing a semiconductor device according to the fifth aspect, before or after the third step, the surface of the polysilicon film and the surface of the silicon substrate exposed by implanting silicon ions are made amorphous. Including the step of forming As described above, before or after the third step, the step of implanting silicon ions to make the exposed polysilicon film surface and the silicon substrate surface amorphous is included, so that the reaction with the implanted oxygen ions or nitrogen ions is promoted. This is effective in increasing the thickness of the non-silicide forming insulating film.
[0026]
According to a seventh aspect of the present invention, in the method of manufacturing a semiconductor device according to the fifth or sixth aspect, in the third step, the implantation dose of oxygen ions or nitrogen ions is 1E16 cm. ^-2 That is all. Thus, during the third step, the implantation dose of oxygen ions or nitrogen ions is 1E16 cm ^-2 As described above, oxygen ions or nitrogen ions are introduced into the surface of the polysilicon film and the surface of the silicon substrate, whereby the non-silicide-forming insulating film can be formed.
[0027]
In the method of manufacturing a semiconductor device according to claim 8, in the method of manufacturing a semiconductor device according to claim 5, 6, or 7, after the fourth step, a second heat treatment is performed on the silicon substrate to remove the implanted ions. A step of forming an oxide film, a nitride film, or an oxynitride film by bonding with silicon in the ion implantation region. Thus, after the fourth step, the second heat treatment is performed on the silicon substrate to combine the implanted ions with the silicon in the ion implantation region to form an oxide film, a nitride film, or an oxynitride film. Therefore, an oxide film, a nitride film, or an oxynitride film can be formed as the non-silicide formation insulating film.
[0028]
According to a ninth aspect of the present invention, in the method of manufacturing a semiconductor device according to the eighth aspect, the second heat treatment is performed in an inert gas atmosphere. As described above, since the second heat treatment is performed in an atmosphere of an inert gas, it is effective for forming an oxide film, a nitride film, or an oxynitride film.
[0029]
According to a tenth aspect of the present invention, in the method of the eighth aspect, the second heat treatment is performed in an oxidizing gas atmosphere. As described above, since the second heat treatment is performed in an atmosphere of an oxidizing gas, it is effective for forming an oxide film or the like.
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a process sectional view illustrating a method for manufacturing a semiconductor device according to the first embodiment of the present invention.
[0031]
In FIG. 1, reference numeral 1 denotes a silicon substrate. 2 is an isolation insulating film. Reference numeral 3 denotes a diffusion layer into which ions are implanted, and forms a source / drain. Reference numeral 5 denotes a resist for forming a non-silicide region. Reference numeral 6 denotes a high melting point metal film used for forming silicide. 7 is a silicide film. 8 is O with strong oxidizing power ₂ An ashing oxide film formed by ashing.
[0032]
Hereinafter, a method for manufacturing the semiconductor device of the present embodiment will be described with reference to FIG.
[0033]
As shown in FIG. 1, when a MOS transistor having a gate electrode made of a polysilicon film is formed on a silicon substrate 1 on which an isolation insulating film 2 and a gate insulating film are formed, the MOS transistor becomes an upper portion of the gate electrode and a source / drain region. A first step of removing the insulating film such as an oxide film remaining on the silicon substrate to expose the polysilicon film surface and the silicon substrate surface; and applying a resist film 5 for forming a non-silicide region on the silicon substrate 1 to form a resist. A second step of patterning; ₂ Ashing is performed to remove the resist film 5, and at the same time, the exposed polysilicon film surface and the silicon substrate surface in the region where the resist film 5 is not present ₂ A third step of forming an oxide film 8 for preventing silicide formation by ashing oxidation, and performing a heat treatment after depositing the refractory metal film 6 on the silicon substrate 1 to form a silicidation reaction on the oxide film 8 for preventing silicide formation. Forming a refractory metal silicide layer 7 by silicidizing the surface of the polysilicon film and the surface of the silicon substrate over the gate electrode and source / drain in the region where the silicide formation preventing oxide film 8 does not exist, And a fifth step of removing the refractory metal film 6 on the silicide formation preventing oxide film 8 that has not been silicided.
[0034]
In this case, in FIG. 1A, after forming an isolation insulating film 2 for electrically separating elements such as transistors on a silicon substrate 1, a gate insulating film and a gate electrode are formed, and a source / drain portion is formed. Is a state in which the injection diffusion layer 3 is formed. In (a), the gate electrode and the like of the transistor are omitted in the drawing. (B) shows a state in which a resist 5 for forming a non-silicide region is applied and patterned. The portion where the resist 5 was present is silicided, and the portion where the resist 5 is not present is patterned so as to be a non-silicide portion.
[0035]
(C-1) is O which has strong oxidizing power. ₂ Ashing is performed to remove the resist, and at the same time, the exposed gate polysilicon surface and the silicon surface where no resist is present are exposed to O 2. ₂ An intermediate stage of forming an oxide film 8 for preventing silicide formation by ashing oxidation is shown. Resist 5 is O ₂ This shows a situation where the silicon surface in a region where the resist 5 does not exist is oxidized while the size is reduced by the ashing (resist 5a).
[0036]
(C-2) shows a state in which the resist 5 is gone. The ashing oxide film 8 is formed on the silicon surface in the region where the resist 5 did not exist, and the ashing oxide film 8 was hardly formed on the silicon surface where the resist 5 existed. In the description of the present embodiment, the ashing oxide film 8 is hardly formed on the silicon surface in the region where the resist 5 is present. ₂ The case where ashing is completed is described. When overashing is performed, an ashing oxide film 8 is gradually formed. However, the oxide film thickness in the region where the resist 5 did not exist is formed to be thicker than the oxide film thickness in the region where the resist 5 exists.
[0037]
(D) is a state where the high melting point metal film 6 is deposited. As the refractory metal film 6, a Co, Ti, Ni film or the like is used. (E) is a heat treatment using RTA or the like for silicide formation, and silicidation is performed at a place where the silicon film 1 and the refractory metal film 6 are in contact with each other. In this state, the refractory metal film 6 on the insulating film such as the film 8 is selectively wet-etched and removed, leaving only the silicide film 7 that has undergone a silicidation reaction. With the above forming method, a silicide region and a non-silicide region can be formed.
[0038]
FIG. 2 shows the first embodiment of the present invention in which O ₂ FIG. 2 is a sectional view of a configuration of an ashing device for generating ashing. O with strong oxidizing power ₂ In order to perform ashing, the plasma density in the chamber 10 is increased and O ₂ This can be achieved by increasing the ion energy and the substrate temperature. In particular, by increasing the RF bias 11 applied to the silicon substrate 1, O ₂ The ion energy increases and the oxidizing power increases. In this embodiment, the plasma density is 5E11 / cm ³ , O ₂ The process was performed with an ion energy of 200 eV and a substrate temperature of normal temperature. Note that O ₂ Plasma density is 1E11 / cm ³ More than 1E12 / cm ³ Below, and O ₂ O under the condition that the ion energy is 100 eV or more and 1000 eV or less. ₂ Ashing may be performed.
[0039]
FIG. 3 is a graph showing ashing time dependence and ashing power dependence of the ashing oxide film 8 according to the first embodiment of the present invention. Since an increase in the ashing oxide film thickness can be achieved by increasing both the ashing time and the power, the ashing oxide film is formed simultaneously with performing the resist ashing utilizing this relationship.
[0040]
A second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a process sectional view illustrating a method for manufacturing a semiconductor device according to the second embodiment of the present invention.
[0041]
In FIG. 4, reference numeral 1 denotes a silicon substrate. 2 is an isolation insulating film. Reference numeral 3 denotes a diffusion layer into which ions are implanted, and forms a source / drain. Reference numeral 5 denotes a resist for forming a non-silicide region. Reference numeral 6 denotes a high melting point metal film used for forming silicide. 7 is a silicide film. Reference numeral 9 denotes an insulating film formed by oxygen implantation or nitrogen implantation.
[0042]
Hereinafter, a method for manufacturing the semiconductor device of the present embodiment will be described with reference to FIG.
[0043]
As shown in FIG. 4, when a MOS transistor having a gate electrode made of a polysilicon film is formed on a silicon substrate 1 on which an isolation insulating film 2 and a gate insulating film are formed, the MOS transistor becomes an upper portion of the gate electrode and a source / drain region. A first step of removing the insulating film such as an oxide film remaining on the silicon substrate to expose the surface of the polysilicon film and the surface of the silicon substrate; and applying a resist film 5 for forming a non-silicide region on the silicon substrate 1 to form a resist. A second step of patterning, and a step of implanting oxygen ions or nitrogen ions using the resist film 5 as a mask to introduce oxygen ions or nitrogen ions into the polysilicon film surface and the silicon substrate surface in a region where the resist film 5 does not exist. Three steps, a fourth step of removing the resist film 5, and a step of forming a refractory metal film 6 on the silicon substrate 1. After the first heat treatment, a first heat treatment is performed to prevent the silicidation reaction in the ion-implanted region, and silicide the polysilicon film surface and the silicon substrate surface over the gate electrode and the source / drain in regions other than the ion-implanted region. A fifth step of forming the refractory metal silicide layer 7 and a sixth step of removing the refractory metal film 6 on the non-silicided ion-implanted region are included.
[0044]
In this case, in FIG. 4A, after forming an isolation insulating film 2 for electrically isolating elements such as transistors on a silicon substrate 1, a gate insulating film and a gate electrode are formed, and a source / drain portion is formed. Is a state in which the injection diffusion layer 3 is formed. In (a), the gate electrode and the like of the transistor are omitted in the drawing. (B) shows a state in which a resist 5 for forming a non-silicide region is applied and patterned. The portion where the resist 5 exists is silicided, and the portion where the resist 5 does not exist is patterned so as to be a non-silicide portion.
[0045]
(C) shows a state in which oxygen ions or nitrogen ions are implanted through the patterned resist, and oxygen ions or nitrogen ions are introduced into the gate polysilicon surface and the silicon surface in a region where the resist 5 does not exist. The implantation dose of oxygen ions or nitrogen ions is 1E16 cm ^-2 That is all. (D): removing the resist 5 and performing a heat treatment (second heat treatment) to combine the implanted oxygen ions or nitrogen ions with the silicon atoms in the ion-implanted region, thereby forming an oxide film, a nitride film, or an oxynitride film. To form The insulating film as the oxide film or the nitride film on the left was used as the non-silicide forming insulating film 9. Note that the heat treatment is preferably performed in an inert gas atmosphere or an oxidizing gas atmosphere.
[0046]
(E) is a state where the high melting point metal film 6 is deposited. As the refractory metal film 6, a Co, Ti, Ni film or the like is used. (F), a heat treatment using RTA or the like (first heat treatment) is performed for silicide formation, silicidation is performed at a place where the silicon film 1 and the refractory metal film 6 are in contact, and thereafter silicidation is not performed. The region, that is, the high melting point metal film 6 on the insulating film such as the non-silicide forming insulating film 9 is selectively wet-etched and removed, leaving only the silicide-reacted silicide film 7. With the above forming method, a silicide region and a non-silicide region can be formed.
[0047]
A third embodiment of the present invention will be described.
[0048]
In the first embodiment, the oxidizing power of O ₂ A non-silicide forming oxide film 8 was formed at the same time as resist ashing using ashing. In the second embodiment, oxygen ions or nitrogen ions are implanted, and the non-silicide forming insulating film 9 is formed by a subsequent heat treatment. In the third embodiment, the non-silicide-forming oxide films (insulating films) 8 and 9 in the first and second embodiments are in a state where they can be more easily formed.
[0049]
It is to add a step of implanting silicon ions to amorphousize the exposed gate polysilicon surface or silicon surface after resist patterning and before ashing in the first embodiment. In the second embodiment, a step of injecting silicon ions before or after oxygen or nitrogen ion implantation to make the exposed gate polysilicon surface or silicon surface amorphous is added.
[0050]
The above-described amorphization by silicon ion implantation in the third embodiment is performed by O ₂ This is because the reaction with the plasma is promoted. That is, a thicker oxide film is formed. Amorphous formation by implanting silicon ions before or after implanting oxygen and nitrogen ions is also effective in increasing the oxide film thickness.
[0051]
【The invention's effect】
According to the method of manufacturing a semiconductor device according to claim 1 of the present invention, a step of applying a resist film for forming a non-silicide region on a silicon substrate and patterning the resist; ₂ The resist film is removed by ashing, and at the same time, the surface of the exposed polysilicon film and the surface of the silicon substrate in the region where no resist film is present are treated with O.sub.2. ₂ Ashing oxidation to form a silicide formation preventing oxide film, and heat treatment after depositing a refractory metal film on a silicon substrate to form a polysilicon film surface and silicon in a region where the silicide formation preventing oxide film does not exist. Since the method includes the steps of silicidizing the substrate surface to form a refractory metal silicide layer and the step of removing the refractory metal film on the silicide formation preventing oxide film, a non-silicide formation insulating film is formed as in the conventional example. It is not necessary to form a pattern by wet etching. That is, instead of etching the non-silicide forming insulating film by wet etching, O ₂ By oxidizing a portion having no resist by ashing, an insulating film for forming a non-silicide can be formed without wet etching. For this reason, it is possible to prevent the separation insulating film from receding due to overetching when the non-silicide forming insulating film is wet-etched, and the sidewall of the transistor from receding. As a result, it is possible to solve the problem of an increase in junction leak current caused by recession due to wet etching.
[0052]
According to the second aspect, in the method of manufacturing a semiconductor device according to the first aspect, in the third step, the thickness of the oxide film for preventing silicide formation is larger than the thickness of the oxide film in the region where the resist film was present. Even if an oxide film is formed in the region where the resist film exists by performing the above, the oxide film thickness in the region where the resist film does not exist is larger than the oxide film thickness, so that the silicide region and the non-silicide region are formed. Can be formed.
[0053]
According to the third aspect, the method of manufacturing a semiconductor device according to the first aspect includes, after the second step, a step of implanting silicon ions to amorphize the exposed surface of the polysilicon film and the surface of the silicon substrate. ₂ Reaction with plasma is promoted, and a thicker oxide film is formed.
[0054]
According to a fourth aspect of the present invention, in the method of manufacturing a semiconductor device according to the first aspect, in the third step, O ₂ Plasma density is 1E11 / cm ³ Above and O ₂ O under the condition that ion energy is 100 eV or more ₂ Oxidizing O ₂ Ashing can be performed.
[0055]
According to the method of manufacturing a semiconductor device according to the fifth aspect of the present invention, a step of applying a resist film for forming a non-silicide region on a silicon substrate and patterning the resist, and oxygen ions or nitrogen ions using the resist film as a mask Implanting oxygen ions or nitrogen ions into the polysilicon film surface and the silicon substrate surface in a region where no resist film is present, removing the resist film, and depositing a high-melting metal film on the silicon substrate. A step of performing a first heat treatment to silicide the surface of the polysilicon film and the surface of the silicon substrate in a region other than the ion implantation region to form a refractory metal silicide layer, and removing the refractory metal film on the ion implantation region Is performed, so that the non-silicide forming insulating film is patterned by wet etching as in the conventional example. It becomes unnecessary to ring formation. That is, the non-silicide-forming insulating film can be formed without wet etching by injecting oxygen or nitrogen instead of etching the non-silicide-forming insulating film by wet etching. For this reason, it is possible to prevent the separation insulating film from receding due to overetching when the non-silicide forming insulating film is wet-etched, and the sidewall of the transistor from receding. As a result, it is possible to solve the problem of an increase in junction leak current caused by recession due to wet etching.
[0056]
According to a sixth aspect of the present invention, the method of manufacturing a semiconductor device according to the fifth aspect includes, before or after the third step, a step of implanting silicon ions to make the exposed polysilicon film surface and the silicon substrate surface amorphous. The reaction with the oxygen ions or nitrogen ions to be performed is promoted, which is effective in increasing the thickness of the non-silicide forming insulating film.
[0057]
According to a seventh aspect, in the method of manufacturing a semiconductor device according to the fifth or sixth aspect, in the third step, the implantation dose of oxygen ions or nitrogen ions is 1E16 cm. ^-2 As described above, oxygen ions or nitrogen ions are introduced into the surface of the polysilicon film and the surface of the silicon substrate, whereby the non-silicide-forming insulating film can be formed.
[0058]
In the eighth aspect, in the method of manufacturing a semiconductor device according to the fifth, sixth or seventh aspect, after the fourth step, a second heat treatment is performed on the silicon substrate to couple the implanted ions with silicon in the ion implantation region. Accordingly, an oxide film, a nitride film, or an oxynitride film can be formed as the non-silicide-forming insulating film.
[0059]
In the ninth aspect, the second heat treatment is performed in an atmosphere of an inert gas, which is effective for forming an oxide film, a nitride film, or an oxynitride film.
[0060]
In the tenth aspect, the second heat treatment is performed in an atmosphere of an oxidizing gas, which is effective for forming an oxide film or the like.
[Brief description of the drawings]
FIG. 1 is a process sectional view illustrating a method for manufacturing a semiconductor device according to a first embodiment of the present invention.
FIG. 2 is a configuration sectional view of an ashing chamber according to the first embodiment of the present invention.
FIG. 3A is a graph showing ashing time dependency of an ashing oxide film according to the first embodiment of the present invention, and FIG. 3B is a graph showing ashing power dependency.
FIG. 4 is a process cross-sectional view for describing a method for manufacturing a semiconductor device according to a second embodiment of the present invention.
FIG. 5 is a process cross-sectional view illustrating a method for manufacturing a semiconductor device in a conventional example.
[Explanation of symbols]
1 Silicon substrate
2 Isolation insulating film
3 Ion-implanted diffusion layer
4 Non-silicide forming insulating film (CVD insulating film)
5 Resist for non-silicide region formation
6. High melting point metal film
7 Silicide film
8 Oxide film for non-silicide region formation
9 Non-silicide formation insulating film

Claims (10)

A method of manufacturing a semiconductor device in which a MOS transistor having a gate electrode made of a polysilicon film is formed on a silicon substrate on which an isolation insulating film and a gate insulating film are formed, A first step of removing the insulating film remaining on the silicon substrate to expose the polysilicon film surface and the silicon substrate surface, and applying a resist film for forming a non-silicide region on the silicon substrate to perform resist patterning In the second step, O ₂ ashing is performed to remove the resist film, and at the same time, the surface of the polysilicon film and the surface of the silicon substrate where the resist film does not exist are exposed to O ₂ ashing to prevent silicide formation. A third step of forming an oxide film for use; Performing a heat treatment after depositing a metal film to silicide the polysilicon film surface and the silicon substrate surface in a region where the silicide formation preventing oxide film does not exist to form a high melting point metal silicide layer; Removing the refractory metal film on the silicide formation preventing oxide film. 2. The method according to claim 1, wherein, in the third step, the thickness of the silicide formation preventing oxide film is larger than the thickness of the oxide film in a region where the resist film exists. 2. The method of manufacturing a semiconductor device according to claim 1, further comprising, after the second step, a step of amorphizing a surface of the polysilicon film and a surface of the silicon substrate exposed by implanting silicon ions. During the third step, _{O 2} plasma density is 1E11 / cm ³ or more, and _{O 2} production process of the ion energy is a semiconductor device according to claim 1, wherein performing the _{O 2} ashing or more conditions 100 eV. A method of manufacturing a semiconductor device in which a MOS transistor having a gate electrode made of a polysilicon film is formed on a silicon substrate on which an isolation insulating film and a gate insulating film are formed, A first step of removing the insulating film remaining on the silicon substrate to expose the polysilicon film surface and the silicon substrate surface, and applying a resist film for forming a non-silicide region on the silicon substrate to perform resist patterning A second step of implanting oxygen ions or nitrogen ions using the resist film as a mask and introducing oxygen ions or nitrogen ions into the polysilicon film surface and the silicon substrate surface in a region where the resist film does not exist; A fourth step of removing the resist film; Performing a first heat treatment after depositing a refractory metal film on the substrate to silicify the polysilicon film surface and the silicon substrate surface in a region other than the ion-implanted region to form a refractory metal silicide layer; A method for manufacturing a semiconductor device, comprising: five steps; and a sixth step of removing a refractory metal film on the ion-implanted region. 6. The method of manufacturing a semiconductor device according to claim 5, further comprising, before or after the third step, a step of implanting silicon ions and amorphizing the exposed polysilicon film surface and the silicon substrate surface. 7. The method of manufacturing a semiconductor device according to claim 5, wherein, in the third step, an implantation dose of oxygen ions or nitrogen ions is 1E16 cm.sup.- ² or more. 6. A step of performing a second heat treatment on the silicon substrate after the fourth step to combine the implanted ions with silicon in the ion-implanted region to form an oxide film, a nitride film, or an oxynitride film. , 6 or 7. 9. The method according to claim 8, wherein the second heat treatment is performed in an inert gas atmosphere. 9. The method according to claim 8, wherein the second heat treatment is performed in an oxidizing gas atmosphere.

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