JP5277733B2 - Semiconductor device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a semiconductor device which allows transistor characteristics to be used stably for a long period of time. <P>SOLUTION: The manufacturing method of the semiconductor device includes a step of forming a gate insulating film 2 on a semiconductor substrate 1, a step of forming an amorphous silicon film 3 on the gate insulating film 2, a step of implanting impurity ions 4 into the amorphous silicon film 3, and a step of forming a gate electrode 3a on the gate insulating film 2 by processing the amorphous silicon film 3. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a semiconductor device and a manufacturing method thereof, and more particularly, to a semiconductor device and a manufacturing method thereof that can suppress electron capture at a gate insulating film or a gate insulating film interface due to long-term use.

  9 (a) to 9 (c) are cross-sectional views showing a manufacturing process of a conventional polycrystalline silicon (polysilicon) film.

  First, as shown in FIG. 9A, a gate oxide film to be a gate insulating film 52 is formed on the surface of a silicon substrate 51 by a thermal oxidation method. Next, a polysilicon film 58 is formed on the gate insulating film 52 by a CVD (Chemical Vapor Deposition) method.

  Next, as shown in FIG. 9B, impurity ions 54 are ion-implanted into the polysilicon film 58. At this time, a relatively light element such as boron or phosphorus is used for the impurity ions 54 to be ion-implanted. Impurity ions 54 are ion-implanted into a polysilicon film 58 serving as a gate electrode material to reduce resistance.

  Thereafter, as shown in FIG. 9C, impurity ions 54 are thermally diffused in the polysilicon film 58 by performing heat treatment on the polysilicon film 58 after the ion implantation. (For example, see Patent Document 1)

  Thereafter, as shown in FIG. 9D, the polysilicon film 58 is processed using a photolithography method and a dry etching method to form a gate electrode 58a. Next, an LDD (Lightly Doped Drain) region 56 made of a low concentration impurity layer is formed on the silicon substrate 51. Next, sidewalls 55 are formed on the side walls of the gate electrode 58 a, and source / drain regions 57 are formed on the silicon substrate 51.

JP 2004-55793 A (paragraphs 0003 to 0005)

  When a charge is applied to the gate electrode of the MOS transistor and the test is performed at a high temperature, a Vth shift (threshold voltage) is observed. That is, when a MOS transistor is used for a long period of time, ions in the gate electrode are trapped in the gate insulating film or the interface of the gate insulating film due to the influence of the electric field of the gate electrode and the source / drain, causing deterioration and fluctuation of transistor characteristics. For this reason, suppression of this phenomenon is an issue for stabilizing the long-term characteristics of the transistor.

  Some embodiments according to the present invention are semiconductors that can be used with stable transistor characteristics for a long period of time by suppressing trapping of impurity ions in the gate insulating film or the interface of the gate insulating film due to long-term use. An apparatus and a manufacturing method thereof.

In order to solve the above problems, a method of manufacturing a semiconductor device according to the present invention includes a step of forming a gate insulating film on a semiconductor substrate,
Forming an amorphous silicon film on the gate insulating film;
Ion implantation of impurity ions into the amorphous silicon film;
Forming a gate electrode on the gate insulating film by processing the amorphous silicon film;
It is characterized by comprising.

  According to the manufacturing method of the semiconductor device, the ion mobility in the gate electrode is reduced by using the amorphous silicon film as the gate electrode material. Thereby, impurity ions in the gate electrode are less likely to be trapped in the gate insulating film or at the gate insulating film interface. As a result, it is possible to suppress deterioration and fluctuation of transistor characteristics, and an effect of long-term stabilization of transistor characteristics can be obtained.

A method of manufacturing a semiconductor device according to the present invention includes a step of forming a gate insulating film on a semiconductor substrate,
Forming an amorphous silicon film on the gate insulating film;
Forming a polysilicon film on the amorphous silicon film;
Ion implantation of impurity ions into the amorphous silicon film and the polysilicon film;
Forming a gate electrode made of the amorphous silicon film and the polysilicon film on the gate insulating film by processing the amorphous silicon film and the polysilicon film;
It is characterized by comprising.

  According to the method for manufacturing a semiconductor device, an amorphous silicon film and a polysilicon film are used as a gate electrode material, and a lower layer portion of the gate electrode that is in contact with the gate insulating film is formed of the amorphous silicon film. The ion mobility in the amorphous silicon film is reduced. Thereby, impurity ions in the gate electrode are less likely to be trapped in the gate insulating film or at the gate insulating film interface. As a result, it is possible to suppress deterioration and fluctuation of transistor characteristics, and an effect of long-term stabilization of transistor characteristics can be obtained. Further, the resistance of the gate electrode can be reduced as compared with the case where the gate electrode is entirely formed of an amorphous silicon film.

A method of manufacturing a semiconductor device according to the present invention includes a step of forming a gate insulating film on a semiconductor substrate,
Forming an amorphous silicon film on the gate insulating film;
Ion implantation of heavy element impurity ions into the amorphous silicon film;
Forming a polysilicon film on the amorphous silicon film;
Ion-implanting light element impurity ions having a mass smaller than that of the heavy element into the polysilicon film;
Forming a gate electrode made of the amorphous silicon film and the polysilicon film on the gate insulating film by processing the amorphous silicon film and the polysilicon film;
It is characterized by comprising.

  According to the semiconductor device manufacturing method, heavy element ions that are less likely to be trapped in the gate insulating film than the light element ions are ion-implanted into the amorphous silicon film under the gate electrode in contact with the gate insulating film. As a result, impurity ions in the gate electrode are less likely to be trapped in the gate insulating film or at the gate insulating film interface than when light element ions are implanted into the amorphous silicon film. As a result, it is possible to suppress deterioration and fluctuation of transistor characteristics, and an effect of long-term stabilization of transistor characteristics can be obtained.

A method of manufacturing a semiconductor device according to the present invention includes a step of forming a gate insulating film on a semiconductor substrate,
Forming an amorphous silicon film on the gate insulating film;
Forming a polysilicon film on the amorphous silicon film;
Introducing the heavy element ions into the amorphous silicon film and the polysilicon film by implanting heavy element impurity ions and light element impurity ions having a smaller mass than the heavy elements into the amorphous silicon film side Introducing the light element ions into the polysilicon film side;
Forming a gate electrode made of the amorphous silicon film and the polysilicon film on the gate insulating film by processing the amorphous silicon film and the polysilicon film;
It is characterized by comprising.

  It is to be noted that ion implantation of heavy element impurity ions and light element impurity ions having a mass smaller than that of the heavy element into the amorphous silicon film and the polysilicon film includes the light element impurity ions and the heavy element impurity ions. This includes the case where ion implantation is performed simultaneously, and also includes the case where light element impurity ions and heavy element impurity ions are implanted separately, and the procedure for ion implantation is the same as that of light element impurity ions and heavy element impurity ions. Whichever is better.

  In the method for manufacturing a semiconductor device according to the present invention, it is preferable that the amorphous silicon film is formed thinner than the polysilicon film. As a result, the film formation time for forming the amorphous silicon film is longer than the film formation time for the polysilicon film, so that the gate electrode formation process can be shortened.

A method of manufacturing a semiconductor device according to the present invention includes a step of forming a gate insulating film on a semiconductor substrate,
Forming an amorphous silicon film on the gate insulating film;
The amorphous silicon film is implanted with heavy element impurity ions and light element impurity ions having a mass smaller than that of the heavy element, thereby introducing the heavy element ions into the lower layer side of the amorphous silicon film and the amorphous silicon film. Introducing the light element ions into the upper layer side of the film;
Forming a gate electrode on the gate insulating film by processing the amorphous silicon film;
It is characterized by comprising.

  According to the semiconductor device manufacturing method, heavy element ions that are difficult to be trapped at the gate insulating film or the interface of the gate insulating film are implanted into the lower layer side of the amorphous silicon film. Thereby, impurity ions in the gate electrode are more difficult to be trapped in the gate insulating film or at the gate insulating film interface than when light element ions are implanted into the lower layer side of the amorphous silicon film. As a result, it is possible to suppress deterioration and fluctuation of transistor characteristics, and an effect of long-term stabilization of transistor characteristics can be obtained.

A semiconductor device according to the present invention includes a semiconductor substrate,
A gate insulating film formed on the semiconductor substrate;
A gate electrode made of an amorphous silicon film formed on the gate insulating film;
Impurity ions introduced into the gate electrode;
It is characterized by comprising.

  According to the semiconductor device described above, the ion mobility in the gate electrode is reduced by using an amorphous silicon film as the gate electrode material. Thereby, impurity ions in the gate electrode are less likely to be trapped in the gate insulating film or at the gate insulating film interface. As a result, it is possible to suppress deterioration and fluctuation of transistor characteristics, and an effect of long-term stabilization of transistor characteristics can be obtained.

  Further, in the semiconductor device according to the present invention, the impurity ions include a heavy element impurity ion introduced into the lower layer side of the gate electrode and a lighter mass that is smaller in mass than the heavy element introduced into the upper layer side of the gate electrode. It is preferable to have elemental impurity ions.

A semiconductor device according to the present invention includes a semiconductor substrate,
A gate insulating film formed on the semiconductor substrate;
A gate electrode formed on the gate insulating film, the lower layer side being an amorphous silicon film and the upper layer side being a polysilicon film;
Impurity ions introduced into the gate electrode;
It is characterized by comprising.

  In the semiconductor device according to the present invention, the impurity ions include heavy element impurity ions introduced into the amorphous silicon film and light element impurity ions having a mass smaller than that of the heavy element introduced into the polysilicon film. It is preferable to have.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1A to 1D are cross-sectional views for explaining a method of manufacturing a semiconductor device according to the first embodiment of the present invention.

  First, as shown in FIG. 1A, a gate oxide film to be a gate insulating film 2 is formed on the surface of a silicon substrate 1 by a thermal oxidation method. Next, an amorphous silicon film 3 is formed on the gate insulating film 2 by a CVD method. At this time, the amorphous silicon film 3 can be formed by thermal decomposition of silane, silanedisilane, or the like at a low temperature of about 200 ° C. to 400 ° C., for example.

  Next, as shown in FIG. 1B, impurity ions 4 are implanted into the amorphous silicon film 3. At this time, the impurity ions 4 implanted into the amorphous silicon film 3 are light element ions, and boron or phosphorus, for example, is used as the light element ions. Thereafter, as shown in FIG. 1C, the silicon substrate 1 is heat-treated to diffuse the impurity ions 4 implanted into the amorphous silicon film 3.

  Next, as shown in FIG. 1D, the amorphous silicon film 3 is processed using a photolithography method and a dry etching method, whereby a gate electrode 3a is formed on the gate insulating film 2. Next, an LDD region 6 made of a low concentration impurity layer is formed on the silicon substrate 1. Next, sidewalls 5 are formed on the sidewalls of the gate electrode 3a. Thereafter, a diffusion layer of the source / drain region 7 is formed on the silicon substrate 1 by an impurity layer.

  As described above, according to the first embodiment of the present invention, the ion mobility in the gate electrode 3a is reduced by using the amorphous silicon film 3 as the gate electrode material. Therefore, the impurity ions 4 in the gate electrode 3a are not easily trapped in the gate insulating film 2 or at the gate insulating film interface. As a result, it is possible to suppress deterioration and fluctuation of transistor characteristics, and an effect of long-term stabilization of transistor characteristics can be obtained.

  Next, a method for manufacturing a semiconductor device according to the second embodiment of the present invention will be described with reference to FIGS. 2 (a) to 2 (c) and FIGS. 3 (a) and 3 (b).

  First, as shown in FIG. 2A, a gate oxide film to be the gate insulating film 12 is formed on the surface of the silicon substrate 11 by a thermal oxidation method. Next, an amorphous silicon film 13 is thinly formed on the gate insulating film 12 by a CVD method. At this time, the amorphous silicon film 13 is desirably formed with a film thickness of about 30 nm to 50 nm.

  Next, as shown in FIG. 2B, a polysilicon film 18 is formed on the amorphous silicon film 13 by a CVD method. At this time, the polysilicon film 18 can be formed by thermal decomposition of monosilane at a temperature of 400 ° C. to 750 ° C., for example. Further, it is desirable that the polysilicon film 18 be formed so as to have a film thickness of 150 nm to 300 nm together with the amorphous silicon film 13.

  Thereafter, as shown in FIG. 2C, impurity ions 14 are implanted into the amorphous silicon film 13 and the polysilicon film 18. At this time, the impurity ions 14 implanted into the amorphous silicon film 13 and the polysilicon film 18 are light element ions, and boron or phosphorus, for example, is used as the light element ions. Thereafter, as shown in FIG. 3A, the silicon substrate 11 is heat treated to diffuse the impurity ions 14 into the amorphous silicon film 13 and the polysilicon film 18.

  Next, as shown in FIG. 3B, the amorphous silicon film 13 and the polysilicon film 18 are processed using a photolithography method and a dry etching method. As a result, a gate electrode having a two-layer structure of an amorphous silicon film 13a and a polysilicon film 18a is formed on the gate insulating film 12. Next, an LDD region 16 made of a low concentration impurity layer is formed on the silicon substrate 11. Next, sidewalls 15 are formed on the sidewalls of the gate electrode. Thereafter, a diffusion layer of the source / drain region 17 is formed on the silicon substrate 11 by an impurity layer.

  As described above, also in the second embodiment of the present invention, the same effect as that of the first embodiment can be obtained. Specifically, by forming the lower layer portion of the gate electrode in contact with the gate insulating film 12 with the amorphous silicon film 13a, the ion mobility in the amorphous silicon film 13a in the vicinity of the gate insulating film 12 can be reduced. As a result, it is possible to suppress the impurity ions 14 in the amorphous silicon film 13a from being trapped in the gate insulating film 12 or at the gate insulating film interface.

  Further, the gate electrode has a two-layer structure of an amorphous silicon film 13a and a polysilicon film 18a. As a result, by forming the polysilicon film 18a in the upper layer portion of the gate electrode, the resistance of the gate electrode can be reduced as compared with the case where the gate electrode is entirely formed of an amorphous silicon film.

  Further, since the film formation time for forming the amorphous silicon film is longer than the film formation time for the polysilicon film, the amorphous silicon film is a thin film of about 30 nm to 50 nm. As a result, the gate electrode formation process can be shortened.

  Next, a method for manufacturing a semiconductor device according to the third embodiment of the present invention will be described with reference to FIGS. 4 (a) to 4 (c) and FIGS. 5 (a) to 5 (c).

  First, as shown in FIG. 4A, a gate oxide film to be the gate insulating film 22 is formed on the surface of the silicon substrate 21 by a thermal oxidation method. Next, an amorphous silicon film 23 is thinly formed on the gate insulating film 22 by CVD. At this time, the amorphous silicon film 23 is desirably formed with a film thickness of about 30 nm to 50 nm.

  Next, as shown in FIG. 4B, impurity ions 29 are implanted into the amorphous silicon film 23. At this time, the impurity ions 29 implanted into the amorphous silicon film 23 are heavy element ions 29, and for example, indium or antimony is used for the heavy element ions 29.

  Next, as shown in FIG. 4C, a polysilicon film 28 is formed on the amorphous silicon film 23 by the CVD method. Thereafter, as shown in FIG. 5A, impurity ions 24 are implanted into the polysilicon film. At this time, the impurity ions 24 implanted into the polysilicon film 28 are light element ions 24. For the light element ions 24, for example, boron or phosphorus is used.

  Thereafter, as shown in FIG. 5B, the silicon substrate 21 is heat-treated to diffuse the light element ions 24 and the heavy element ions 29 implanted into the amorphous silicon film 23 and the polysilicon film 28. By this heat treatment, the light element ions 24 are mainly thermally diffused on the polysilicon film 28 side, and the heavy element ions 29 are mainly thermally diffused on the amorphous silicon film 23 side.

  Next, as shown in FIG. 5C, the amorphous silicon film 23 and the polysilicon film 28 are processed using a photolithography method and a dry etching method. Thus, a gate electrode having a two-layer structure of an amorphous silicon film 23a and a polysilicon film 28a is formed on the gate insulating film 22. Next, an LDD region 26 made of a low concentration impurity layer is formed on the silicon substrate 21. Next, a sidewall 25 is formed on the side wall of the gate electrode. Thereafter, a diffusion layer of the source / drain region 27 is formed on the silicon substrate 21 by an impurity layer.

  As described above, also in the third embodiment of the present invention, the same effect as in the second embodiment can be obtained.

  Further, heavy element ions are ion-implanted into the amorphous silicon film that is the lower layer portion of the gate electrode, and then light element ions are implanted into the polysilicon film that is the upper layer portion of the gate electrode. In other words, heavy element ions that are less likely to be trapped in the gate insulating film than light element ions are ion-implanted into the amorphous silicon film under the gate electrode in contact with the gate insulating film. Therefore, impurity ions in the gate electrode are further less likely to be trapped in the gate insulating film or at the gate insulating film interface than when light element ions are implanted into the amorphous silicon film.

  Next, a method for manufacturing a semiconductor device according to the fourth embodiment of the present invention will be described with reference to FIGS. 6 (a) to 6 (c) and FIGS. 7 (a) and 7 (b).

  First, as shown in FIG. 6A, a gate oxide film to be the gate insulating film 32 is formed on the surface of the silicon substrate 31 by a thermal oxidation method. Next, an amorphous silicon film 33 is thinly formed on the gate insulating film 32 by the CVD method. At this time, the amorphous silicon film 33 is desirably formed with a film thickness of about 30 nm to 50 nm.

  Next, as shown in FIG. 6B, a polysilicon film 38 is formed on the amorphous silicon film 33 by a CVD method. At this time, the amorphous silicon film 33 and the polysilicon film 38 can be continuously formed by the same CVD apparatus without dividing the process.

  Thereafter, as shown in FIG. 6C, impurity ions of light element ions 34 and heavy element ions 39 are simultaneously implanted into the amorphous silicon film 33 and the polysilicon film 38. At this time, the introduced ion gas is made into a plurality of ion species, the heavy element ions 39 are deeply implanted into the amorphous silicon film 33, and the light element ions 34 are shallowly implanted into the polysilicon film 38. In the present embodiment, the light element ions 34 and the heavy element ions 39 are simultaneously implanted. However, the light element ions 34 and the heavy element ions 39 can be separately implanted. Either the light element ion 34 or the heavy element ion 39 may be first.

  Thereafter, as shown in FIG. 7A, the silicon substrate 31 is heat-treated to diffuse the light element ions 34 and the heavy element ions 39 implanted into the amorphous silicon film 33 and the polysilicon film 38. By this heat treatment, the light element ions 34 are thermally diffused mainly on the polysilicon film 38 side, and the heavy element ions 39 are mainly thermally diffused on the amorphous silicon film 33 side.

  Next, as shown in FIG. 7B, the amorphous silicon film 33 and the polysilicon film 38 are processed using a photolithography method and a dry etching method. Thus, a gate electrode having a two-layer structure of an amorphous silicon film 33a and a polysilicon film 38a is formed on the gate insulating film 32. Next, an LDD region 36 made of a low concentration impurity layer is formed on the silicon substrate 31. Next, sidewalls 35 are formed on the sidewalls of the gate electrode. Thereafter, a diffusion layer of the source / drain region 37 is formed on the silicon substrate 31 by the impurity layer.

  As described above, also in the fourth embodiment of the present invention, the same effect as that of the third embodiment can be obtained. Further, heavy element ions and light element ions are simultaneously implanted into the amorphous silicon film and the polysilicon film, respectively. Therefore, there is no need to divide the process.

  Next, a method for manufacturing a semiconductor device according to the fifth embodiment of the present invention will be described with reference to FIGS.

  First, as shown in FIG. 8A, a gate oxide film to be the gate insulating film 42 is formed on the surface of the silicon substrate 41 by a thermal oxidation method. Next, an amorphous silicon film 43 is formed on the gate insulating film 42 by a CVD method.

  Next, as shown in FIG. 8B, impurity ions of heavy element ions 49 and light element ions 44 are simultaneously implanted into the amorphous silicon film 43. At this time, the introduced ion gas is made into a plurality of ion species, heavy element ions 49 are deeply implanted into the amorphous silicon film 43, and light element ions 44 are shallowly implanted into the amorphous silicon film 43. In this embodiment, the light element ions 44 and the heavy element ions 49 are simultaneously implanted. However, the light element ions 44 and the heavy element ions 49 can be separately implanted. Either the light element ion 44 or the heavy element ion 49 may be first.

  Thereafter, as shown in FIG. 8C, the silicon substrate 41 is subjected to a heat treatment to diffuse the light element ions 44 and heavy element ions 49 implanted into the amorphous silicon film 43. Thereby, impurities due to the light element ions 44 in the amorphous silicon film 43 are mainly thermally diffused on the upper layer side, and impurity ions due to the heavy element ions 49 are mainly thermally diffused on the lower layer side. As a result, the impurity diffused in the amorphous silicon film 43 has a higher ratio of light element ions 44 on the upper layer side of the amorphous silicon film 43 and a higher ratio of heavy element ions 49 on the lower layer side of the amorphous silicon film 43. A two-layer structure consisting of light element ions 44 and heavy element ions 49 is formed.

  Next, as shown in FIG. 8D, the amorphous silicon film 43 is processed using a photolithography method and a dry etching method. As a result, a gate electrode 43 a is formed on the gate insulating film 42. Next, an LDD region 46 made of a low concentration impurity layer is formed on the silicon substrate 41. Next, sidewalls 45 are formed on the sidewalls of the gate electrode 43a. Thereafter, a diffusion layer of the source / drain region 47 is formed on the silicon substrate 41 by an impurity layer.

  As described above, also in the fifth embodiment of the present invention, the same effect as that of the first embodiment can be obtained.

  Further, in the step of ion-implanting impurities into the amorphous silicon film 43, ion implantation of heavy element ions 49 that are difficult to be trapped at the gate insulating film 42 or the interface of the gate insulating film 42 is performed on the lower layer side. Therefore, impurity ions in the gate electrode are more unlikely to be trapped in the gate insulating film or at the gate insulating film interface than when light element ions are implanted into the lower layer side of the amorphous silicon film.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the first to fifth embodiments, ion implantation of impurity ions is performed after the amorphous silicon film is formed, but the film is formed by a CVD method in which an amorphous silicon forming gas and a gas of an ion species to be introduced are reacted at the same time. Thus, impurity ions can be introduced in the same process as the amorphous silicon film formation. Similarly, it is possible to introduce impurity ions in the same process as the polysilicon film formation.

(A), (b), (c) and (d) are sectional drawings for demonstrating the manufacturing method of the semiconductor device which concerns on 1st Embodiment. (A), (b) and (c) are sectional drawings for demonstrating the manufacturing method of the semiconductor device which concerns on 2nd Embodiment. (A) And (b) is sectional drawing for demonstrating the next process of FIG. (A), (b) and (c) is sectional drawing for demonstrating the manufacturing method of the semiconductor device which concerns on 3rd Embodiment. (A), (b) and (c) is sectional drawing for demonstrating the next process of FIG. (A), (b) and (c) is sectional drawing for demonstrating the manufacturing method of the semiconductor device which concerns on 4th Embodiment. (A) And (b) is sectional drawing for demonstrating the next process of FIG. (A), (b), (c) and (d) is sectional drawing for demonstrating the manufacturing method of the semiconductor device which concerns on 5th Embodiment. (A), (b), (c) and (d) is sectional drawing for demonstrating the manufacturing method of the conventional semiconductor device.

Explanation of symbols

  1, 11, 21, 31, 41, 51 ... silicon substrate, 2, 12, 22, 32, 42, 52 ... gate insulating film, 3, 13, 23, 33, 43, 3a, 13a, 23a , 33a, 43a ... amorphous silicon film (gate electrode), 4, 14, 24, 34, 44, 54 ... impurity ions (light element ions), 5, 15, 25, 35, 45, 55,. Side walls, 7, 17, 27, 37, 47, 57... Source / drain regions, 18, 28, 38, 58, 18a, 28a, 38a, 58a... Polysilicon films (gate electrodes), 29 , 39, 49... Impurity ions (heavy element ions), 6, 16, 26, 36, 46, 56... LDD regions

Claims (2)

Forming a gate insulating film on the semiconductor substrate;
Forming an amorphous silicon film on the gate insulating film;
The amorphous silicon film is implanted with heavy element impurity ions and light element impurity ions having a mass smaller than that of the heavy element, thereby introducing the heavy element ions into the lower layer side of the amorphous silicon film and the amorphous silicon film. Introducing the light element ions into the upper layer side of the film ;
Forming a gate electrode on the gate insulating film by processing the amorphous silicon film;
A method for manufacturing a semiconductor device, comprising: A semiconductor substrate;
A gate insulating film formed on the semiconductor substrate;
A gate electrode made of an amorphous silicon film formed on the gate insulating film;
Impurity ions introduced into the gate electrode;
Equipped with,
The impurity ions, and heavy elements impurity ions introduced into the lower layer of the gate electrode, to have a impurity ions of small light element of mass from introduced the heavy elements on the upper side of the gate electrode A featured semiconductor device.

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