JPH09102612A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor device wherein the dissolving of a problem of uniformity of film quality of a polycrystalline silicon film in a low temperature process, the improvement of annihilation ratio of crystal defect, the improvement of characteristics of a thin film transistor, and the uniforming of characteristics in a substrate are possible. SOLUTION: An amorphous silicon film 12 is doped with fluorine before crystallization of a polycrystalline silicon film 13 not through an oxide film, before an element isolation process, by combining laser annealing with fluorine doping. After that, crystallization of the amorphous silicon film 12 and activation of fluorine are simultaneously performed by laser annealing. Thereby crystal defect in an active layer film 14 is annihilated, and characteristics of film quality is improved as a whole. Hence, the problem of uniformity of film quality of the active layer film 14 is dissolved, and excellent characteristics of a polycrystalline silicon thin film transistor in a low temperature process can be obtained in a large-sized substrate without irregularity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device manufacturing method, and more particularly to a thin film transistor manufacturing method.

[0002]

2. Description of the Related Art In recent years, liquid crystal display elements have been actively developed, and in particular, thin film transistors (Thin Film Transistors) having an active layer formed of polycrystalline silicon have been developed.
istors (TFTs) or thin film transistor arrays are being actively developed for application to liquid crystal display devices. The application of a thin film transistor (TFT) to a liquid crystal display element is carried out by applying it to a switching element of a pixel section which is a display section or applying a thin film transistor to a driving circuit of the switching element of the pixel section. ing. For example, an active matrix liquid crystal display element composed of a TFT array substrate using a thin film transistor as a switching element has been actively developed.

A conventional method of manufacturing a thin film transistor using laser annealing will be described below with reference to FIG. FIG. 4 is an explanatory view showing a manufacturing process of a conventional method of manufacturing a thin film transistor in which laser annealing is performed.

First, an amorphous silicon film having a thickness of about 500 angstroms is formed on the entire surface of a quartz (SiO ₂ ) substrate 41, and laser annealing is performed to crystallize the amorphous silicon film to form a polycrystalline film. A silicon film 42 is formed (FIG. 4A).

The polycrystalline silicon film 42 is isolated by chemical dry etching to form an active layer 43 (FIG. 4B).

After forming the active layer 43, an oxide film is formed on the entire surface of the quartz substrate 41 by a CVD method to form a gate oxide film 44 of the active layer 43 (FIG. 4C).

After forming the gate oxide film 44, a molybdenum tungsten film is formed on the entire surface of the quartz substrate 41 to a thickness of about 2000 Å, and a gate electrode 45 is formed by chemical dry etching (FIG. 4D). .

After forming the gate electrode 45, boron fluoride (B) is formed by self-alignment using the gate electrode 45 as a mask.
F ₂ ) is doped at a dose of about 1 × 10 ¹⁵ (cm ⁻² ) to form high concentration regions 43b at both ends of the active layer 43 and a channel region 43a in the middle of the high concentration regions 43b at both ends. (FIG. 4 (e)).

Further, an interlayer insulating film 46 is formed to a thickness of about 4000 angstrom by the CVD method, and then RI is formed.
A contact hole is formed by E, an aluminum electrode is formed in the contact hole formation portion, and the source / drain electrode 47 is formed by etching the aluminum electrode, thereby completing the thin film transistor (FIG. 4F).

By the way, in order to cope with the problems such as the large screen of the liquid crystal display device applying the thin film transistor array using the active layer of polycrystalline silicon and the reduction of the manufacturing cost, an inexpensive glass substrate having a low heat resistant temperature is used. The process temperature must be lowered because of the need to use it.

When the maximum process temperature is set to 600 ° C. in order to use a glass substrate having a low heat resistant temperature, the maximum process temperature is set to 900 ° C. due to various factors such as deterioration of the crystallinity of the active layer and recovery. The transistor characteristics are significantly deteriorated as compared with the thin film transistor manufactured by the manufacturing process described above.

As a means for improving the transistor characteristics by these low temperature processes, there is known a method of doping the active layer with fluorine and activating it to eliminate crystal defects.

A conventional method of manufacturing a P-type thin film transistor in which fluorine is doped will be described below with reference to FIG. FIG. 5 shows a conventional P doped with fluorine.
FIG. 6 is an explanatory view showing a manufacturing process of a method for manufacturing a thin film transistor.

First, a polycrystalline silicon film is formed on the entire surface of a quartz (SiO ₂ ) substrate 51 to a thickness of about 500 Å, and a polycrystalline silicon film 52a is formed by chemical dry etching. Polycrystalline silicon film 52a
After the formation, an oxide film 53 is formed on the entire surface by a CVD method to have a thickness of 700 angstrom. Next, fluorine ions are doped on the entire surface with a dose amount of about 1 × 10 ¹⁵ (cm ⁻² ) and activated (FIG. 5A).

The oxide film 53 containing fluorine is removed with an ammonium fluoride solution (FIG. 5 (b)).

After removing the oxide film 53, the polycrystalline silicon film 52 is removed.
A gate oxide film 54 of a polycrystalline silicon film 52a is formed on the entire surface of the quartz substrate 51 on which a has been formed (FIG. 5).
(C)).

A molybdenum-tungsten film having a thickness of 2000 angstrom is formed on the entire surface of the gate oxide film 54, and the gate electrode 5 is formed by chemical dry etching.
5 is formed (FIG. 5D).

After forming the gate electrode 55, boron fluoride (B) is formed by self-alignment using the gate electrode 55 as a mask.
F ₂ ) is doped with a dose amount of about 1 × 10 ¹⁵ (cm ⁻² ), and high concentration regions 53 are formed on both ends of the polycrystalline silicon film 52a.
b, and the channel regions 52c are formed in the middle of the high concentration regions 53b at both ends (FIG. 5E).

Further, after forming an interlayer insulating film 56 to a thickness of about 4000 angstrom by the CVD method, RI
A contact hole is formed by E, an aluminum electrode is formed in the contact hole forming portion, and the source / drain electrode 57 is formed by etching the aluminum electrode to complete a P-type thin film transistor (FIG. 5).
(F)).

As described above, usually, after the element isolation process of the polycrystalline silicon film, an oxide film is formed as an upper layer of the active layer, fluorine is doped through the oxide film and activated to eliminate crystal defects. ing.

[0021]

However, a conventional method of manufacturing a thin film transistor using laser annealing,
The conventional P-type thin film transistor manufacturing methods that perform fluorine doping have the following problems.

In the conventional method of manufacturing a thin film transistor using laser annealing, there is a problem that the uniformity of the film quality of the polycrystalline silicon film is deteriorated due to uneven irradiation, and such a polycrystalline silicon film is used as an active layer. When a thin film transistor is manufactured as described above, variations in transistor characteristics within the substrate increase.

In the conventional method of manufacturing a P-type thin film transistor which carries out fluorine doping, there is a problem that the crystallinity of the polycrystalline silicon film is destroyed by doping fluorine ions through the oxide film, and at the time of activation. Although the crystallinity is restored by the heat treatment, since the doping and activation are performed after the element isolation process, only small crystal grains are formed, which causes deterioration of characteristics. Also,
Since fluorine ions are doped through the oxide film, a large amount of oxygen is mixed into the active layer due to a knock-on phenomenon, which also causes characteristic deterioration.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method of manufacturing a thin film transistor using laser annealing and a method of manufacturing a P-type thin film transistor in which fluorine doping is carried out. It is intended to solve the problem of uniformity of film quality of a silicon film, improve the extinction rate of crystal defects, improve the characteristics of thin film transistors, and make the characteristics within a substrate uniform.

[0025]

According to the method of manufacturing a semiconductor device of the present invention, the first step of forming an amorphous silicon film on a substrate and the implantation of fluorine ions into the amorphous silicon film. A second step, a third step of crystallizing the amorphous silicon film into a polycrystalline silicon film and performing laser annealing for activating fluorine ions, and a polycrystalline silicon film in which fluorine ions are activated A step of removing the portion other than the portion to be the active layer to separate the elements to form an active layer, a fifth step of forming a gate oxide film on the substrate on which the active layer is formed, and a gate oxidation step. A sixth step of forming a gate electrode on the film, a seventh step of implanting impurity molecular ions by self-alignment using the gate electrode as a mask, a contact hole is formed at a predetermined position, and a source electrode is formed in the contact hole forming portion. And an eighth step of forming a drain electrode. In order to improve the variation in the uniformity of the film quality of the polycrystalline silicon film crystallized by laser annealing due to uneven irradiation, laser annealing is performed. Since it is combined with fluorine doping, the drawback of the manufacturing method by laser annealing, that is, the problem that the uniformity of the film quality of the polycrystalline silicon film is deteriorated due to the uneven irradiation can be significantly improved. In particular, before the element isolation step, the amorphous silicon film before crystallization of the polycrystalline silicon film is doped with fluorine without passing through an oxide film, and then laser annealing is performed to crystallize the amorphous silicon film and activate fluorine. By simultaneously performing the crystallization, the crystal defects in the active layer film are eliminated, and the property of the film quality is improved as a whole, so that the problem of the uniformity of the film quality of the active layer film can be solved. Good transistor characteristics of a silicon thin film transistor can be obtained without variation even on a large substrate.

Fluorine ion implantation is performed at a dose of 5 × 10.
^When the amount is in the range of ¹⁴ cm ⁻² to 3 × 10 ¹⁵ cm ⁻² and the accelerating voltage is about 30 KeV, the above-mentioned effect is maximized.

First Forming Polycrystalline Silicon Film on Substrate
Other than the step, the second step of implanting fluorine ions into the polycrystalline silicon film, the third step of activating the fluorine ions, and the portion of the polycrystalline silicon film in which the fluorine ions are activated, which will be the active layer. Is removed to separate the elements to form an active layer, a fifth step of forming a gate oxide film on the substrate on which the active layer is formed, and a gate electrode formed on the gate oxide film. And a seventh step of implanting impurity molecular ions by self-alignment using the gate electrode as a mask, and forming a contact hole at a predetermined position,
An eighth step of forming a source electrode and a drain electrode in the contact hole forming portion is provided, and the crystallinity of the polycrystalline silicon film is prevented and oxygen is not mixed into the active layer due to a knock-on phenomenon. Therefore, before the element isolation step, the active layer was directly doped with fluorine without passing through an oxide film, and then activated, so that the crystal defect annihilation effect of fluorine can be exerted with high efficiency, and It is possible to solve the problem of uniformity of the film quality of the active layer film by avoiding the mixing of oxygen and improving the film quality characteristics as a whole, and it is possible to obtain good transistor characteristics of the polycrystalline silicon thin film transistor by the low temperature process. It is possible to improve the throughput.

First Forming Polycrystalline Silicon Film on Substrate
Process, a second process of implanting fluorine ions into the polycrystalline silicon film, a third process of forming an oxide film on the polycrystalline silicon film, a fourth process of activating fluorine ions, and an oxidation process. Fifth step of peeling off the film, removing a portion other than a portion of the polycrystalline silicon film in which fluorine ions are activated to be an active layer to separate elements to form an active layer, and a substrate on which the active layer is formed A sixth step of forming a gate oxide film thereon, a seventh step of forming a gate electrode on the gate oxide film, and an eighth step of implanting impurity molecule ions by self-alignment using the gate electrode as a mask, A ninth step of forming a contact hole at a predetermined position and forming a source electrode and a drain electrode in the contact hole forming portion, the crystallinity of the polycrystalline silicon film and an acid caused by a knock-on phenomenon. In order to avoid the contamination of the active layer into the active layer, fluorine was directly doped into the active layer without passing through the oxide film before the element isolation step, and then an oxide film was formed and activated. To solve the problem of uniformity of the film quality of the active layer by maximizing the effect of eliminating crystal defects, avoiding the mixing of oxygen from the oxide film into the active layer, and improving the quality of the film as a whole. Therefore, good transistor characteristics of the polycrystalline silicon thin film transistor by the low temperature process can be obtained.

The dose of fluorine ions is such that the fluorine concentration in the active layer is 1 × 10 ¹⁷ cm when the semiconductor device is completed.
^{If the} amount is a value within the range of ⁻³ to 1 × 10 ¹⁹ cm ⁻³ , the above function and effect are maximized.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a method for manufacturing a semiconductor device according to the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view of an embodiment of a method of manufacturing a thin film transistor using laser annealing according to the present invention. Hereinafter, description will be made in the order of steps.

First, an amorphous silicon film 12 is formed on the entire surface of a quartz (SiO ₂ ) substrate 11 to a thickness of about 500 Å, and fluorine is dosed at about 1 × 10 ¹⁵ (cm 2).
^-2 ), the entire surface is doped with an accelerating voltage of about 30 (KeV) (FIG. 1 (a)).

Crystallization of the amorphous silicon film 12 doped with fluorine and activation of fluorine ions are performed by laser annealing to form a polycrystalline silicon film 13 (FIG. 1).
(B)).

The polycrystalline silicon film 13 is subjected to element isolation by chemical dry etching to form an active layer 14 (FIG. 1 (c)).

An oxide film is formed on the entire surface of the quartz substrate 11 after the formation of the active layer 14 by the CVD method to form a gate oxide film 15 of the active layer 14 (FIG. 1 (d)).

A molybdenum tungsten film having a thickness of about 2000 angstroms is formed on the entire surface of the quartz substrate 11 after the gate oxide film 15 is formed, and a gate electrode 16 is formed by chemical dry etching (FIG. 1 (e)). .

After forming the gate electrode 16, boron fluoride (B) is formed by self-alignment using the gate electrode 16 as a mask.
F ₂ ) is doped with a dose amount of about 1 × 10 ¹⁵ (cm ⁻² ) to form high concentration regions 14b at both ends of the active layer 14 and a channel region 14a in the middle of the high concentration regions 14b at both ends. (FIG. 1 (f)).

Further, after the interlayer insulating film 17 is formed to a thickness of about 4000 angstrom by the CVD method, RI is formed.
A contact hole is formed by E, an aluminum electrode is formed in the contact hole formation portion, and the source / drain electrode 18 is formed by etching the aluminum electrode, thereby completing a thin film transistor (FIG. 1G).

As described above, in the method of manufacturing a thin film transistor using laser annealing according to the present invention, variations in film quality uniformity due to irradiation unevenness of a polycrystalline silicon film crystallized by laser annealing are improved. Therefore, the defect of the manufacturing method by laser annealing is compensated by combining laser annealing and fluorine doping. In particular, as described above, before the element isolation step, the amorphous silicon film before crystallization of the polycrystalline silicon film is doped with fluorine without passing through an oxide film, and then the amorphous silicon film is crystallized by laser annealing. By simultaneously activating and fluorine, the crystal defects in the active layer film are eliminated, and by improving the quality of the film as a whole, the problem of uniformity of the film quality of the active layer film can be solved. It is possible to obtain good transistor characteristics of the polycrystalline silicon thin film transistor by the process without variation even on a large substrate.

FIG. 2 is an explanatory view showing a manufacturing process of a method of manufacturing a thin film transistor for fluorine doping according to the present invention. Hereinafter, description will be made in the order of steps.

First, a polycrystalline silicon film 22a is formed on the entire surface of a quartz (SiO ₂ ) substrate 21 to a thickness of about 500 Å, and fluorine is dosed at about 1 × 10 ¹⁵ (cm 2).
^-2 ), the entire surface is doped with an accelerating voltage of about 30 (KeV) (FIG. 2A).

In order to further enhance the effect of the present invention, the dose of fluorine ions is such that the fluorine concentration in the active layer is 1 × 10 ¹⁷ when the thin film transistor is completed.
cm ^-3 to may be an amount that a value within the range of 1 × 10 ¹⁹ cm ^-3.

After the polycrystalline silicon film 22a is formed, an oxide film 23 is formed on the entire surface by the CVD method and the temperature is about 600.degree.
Activation is performed in ₂ atmospheres for about 3 hours (FIG. 2 (b)).

After activation, the oxide film 23 is peeled off with an ammonium fluoride solution, and then the polycrystal silicon film 22a is subjected to element isolation by chemical dry etching to form an element isolation polycrystal silicon film 22b (FIG. 2).
(C)).

A gate oxide film 24 of the element isolation polycrystalline silicon film 22b is formed on the entire surface of the quartz substrate 21 on which the element isolation polycrystalline silicon film 22b is formed (FIG. 2D).

A molybdenum-tungsten film having a thickness of 2000 angstrom is formed on the entire surface of the gate oxide film 24, and the gate electrode 2 is formed by chemical dry etching.
5 is formed (FIG. 2E).

After forming the gate electrode 25, boron fluoride (B) is formed by self-alignment using the gate electrode 25 as a mask.
F ₂ ) is doped with a dose amount of about 1 × 10 ¹⁵ (cm ⁻² ), and high-concentration regions 22c are formed at both ends of the element isolation polycrystalline silicon film 22b, and a channel region is formed in the middle of the high-concentration regions 22c at both ends. 22d are formed respectively (FIG. 2 (f)).

Further, an interlayer insulating film 26 is formed to a thickness of about 4000 angstrom by the CVD method, and then RI is formed.
A contact hole is formed by E, an aluminum electrode is formed in the contact hole formation portion, and the source / drain electrode 27 is formed by etching the aluminum electrode, thereby completing the thin film transistor (FIG. 2G).

As described above, in the method of manufacturing a thin film transistor for fluorine doping according to the present invention, in order to prevent the crystallinity of the polycrystalline silicon film from being destroyed and oxygen from being mixed into the active layer due to a knock-on phenomenon, Before the element isolation step, fluorine is directly doped into the active layer without passing through the oxide film, and then the oxide film is formed and activated. This maximizes the effect of eliminating crystal defects of fluorine, avoids the mixing of oxygen from the oxide film into the active layer, and improves the quality of the film as a whole, thereby improving the uniformity of the film quality of the active layer film. The problem can be solved, and good transistor characteristics of the polycrystalline silicon thin film transistor by the low temperature process can be obtained.

FIG. 3 is a graph (FIG. 3 (a)) showing the characteristics of a P-type thin film transistor obtained by the method of manufacturing a thin film transistor for fluorine doping according to the present invention.
It is a graph (FIG.3 (b)) which shows the characteristic of the P-type thin film transistor obtained by the manufacturing method of the conventional P-type thin film transistor which performs fluorine doping. Comparing the values of the drain current ID on the left vertical axis of both graphs, it can be seen that the leak current is reduced. Further, it can be seen from the waveform of the graph in the vicinity of the voltage VG of the gate voltage VG on the horizontal axis that the rising characteristic is improved.

In the structure of the method of manufacturing a thin film transistor for fluorine doping according to the present invention as described above, either solid phase growth or laser crystallization growth may be used as a method for forming a polycrystalline silicon film. The same effect can be obtained by doping fluorine ions by ion doping.

Further, the characteristics of the thin film transistor are improved when the oxide film 23 is formed at the time of activation, but when the characteristic level is necessary and sufficient and the throughput is prioritized, the oxide film 23 is formed. Need not be formed.

[0053]

As described above, according to the method of manufacturing a semiconductor device of the present invention, it is possible to improve the unevenness of the film quality of the polycrystalline silicon film crystallized by laser annealing due to uneven irradiation. Therefore, since the laser annealing and the fluorine doping are combined, the drawback of the manufacturing method by the laser annealing, that is, the problem that the uniformity of the film quality of the polycrystalline silicon film is deteriorated due to uneven irradiation can be significantly improved. it can. In particular, before the element isolation step, the amorphous silicon film before crystallization of the polycrystalline silicon film is doped with fluorine without passing through an oxide film, and then laser annealing is performed to crystallize the amorphous silicon film and activate fluorine. By simultaneously performing the crystallization, the crystal defects in the active layer film are eliminated, and the property of the film quality is improved as a whole, so that the problem of the uniformity of the film quality of the active layer film can be solved. Good transistor characteristics of a silicon thin film transistor can be obtained without variation even on a large substrate.

The dose of fluorine ion implantation is 5 × 10.
^When the amount is in the range of ¹⁴ cm ⁻² to 3 × 10 ¹⁵ cm ⁻² and the accelerating voltage is about 30 KeV, the above-mentioned effect is maximized.

In order to prevent the crystallinity of the polycrystalline silicon film from being broken and the oxygen to be mixed into the active layer due to the knock-on phenomenon, fluorine is directly doped into the active layer without passing through the oxide film before the element isolation step, Next, an oxide film was formed and activated, so the effect of eliminating crystal defects of fluorine is maximized, oxygen is prevented from being mixed into the active layer from the oxide film, and overall film quality characteristics are improved. By doing so, it is possible to solve the problem of the uniformity of the film quality of the active layer film, and it is possible to obtain good transistor characteristics of the polycrystalline silicon thin film transistor by the low temperature process.

If the necessary and sufficient level of characteristics of the thin film transistor can be secured, the throughput can be improved by not forming the oxide film at the time of activation of fluorine ions.

The dose of fluorine ions is such that when the semiconductor device is completed, the fluorine concentration in the active layer is 1 × 10 ¹⁷ cm 2.
^{If the} amount is a value within the range of ⁻³ to 1 × 10 ¹⁹ cm ⁻³ , the above function and effect are maximized.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an embodiment of a method of manufacturing a thin film transistor using laser annealing according to the present invention.

FIG. 2 is an explanatory view showing a manufacturing process of a method of manufacturing a thin film transistor for performing fluorine doping according to the present invention.

FIG. 3 is a graph showing the characteristics of a P-type thin film transistor obtained by the present invention and the conventional method of manufacturing a thin film transistor for fluorine doping.

FIG. 4 is an explanatory view showing a manufacturing process of a conventional method for manufacturing a P-type thin film transistor which is doped with fluorine.

FIG. 5 is an explanatory view showing a manufacturing process of a conventional method of manufacturing a thin film transistor in which laser annealing is performed.

[Explanation of symbols]

 11, 21, 41, 51 Quartz substrate 12 Amorphous silicon film 13, 22a, 42, 52a Polycrystalline silicon film 14, 43 Active layer 14a, 22d, 43a, 52c Channel region 14b, 22c, 43b, 52b High concentration region 15, 24, 44, 54 Gate oxide film 16, 25, 45, 55 Gate electrode 17, 26, 46, 56 Inter-layer insulation film 18, 27, 47, 57 Source / drain electrode 22b Element isolation polycrystalline silicon film 23, 53 Oxide film

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H01L 29/78 627G

Claims (5)

[Claims] 1. A first method for forming an amorphous silicon film on a substrate.
And a second step of implanting fluorine ions into the amorphous silicon film, and a laser annealing process for crystallizing the amorphous silicon film into a polycrystalline silicon film and activating the fluorine ions. A third step of performing, a fourth step of removing an element other than an active layer portion of the polycrystalline silicon film in which the fluorine ions are activated to form an active layer by element isolation, and the active layer A fifth step of forming a gate oxide film on the substrate on which the gate electrode is formed, a sixth step of forming a gate electrode on the gate oxide film, and impurity molecular ions by self-alignment using the gate electrode as a mask. And a seventh step of forming a contact hole at a predetermined position and forming a source electrode and a drain electrode at the contact hole forming portion. Method for manufacturing guiding device. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the implantation of the fluorine ions is performed at a dose of 5 × 10 5.
^A method for manufacturing a semiconductor device, characterized in that the operation is performed at an acceleration voltage of about 30 KeV in an amount in the range of ¹⁴ cm ^-2 to 3 x 10 ¹⁵ cm ^-2 . 3. A first method for forming a polycrystalline silicon film on a substrate
And a second step of implanting fluorine ions into the polycrystalline silicon film, a third step of activating the fluorine ions, and an active layer of the polycrystalline silicon film in which the fluorine ions are activated. A fourth step of removing a portion other than a portion to be an element and isolating the element to form an active layer; a fifth step of forming a gate oxide film on the substrate having the active layer formed thereon; A sixth step of forming a gate electrode on the film, a seventh step of implanting impurity molecular ions by self-alignment using the gate electrode as a mask, and forming a contact hole at a predetermined position, and forming a contact hole in the contact hole forming portion. An eighth step of forming a source electrode and a drain electrode, and a method of manufacturing a semiconductor device. 4. A first method for forming a polycrystalline silicon film on a substrate.
And a second step of implanting fluorine ions into the polycrystalline silicon film, a third step of forming an oxide film on the polycrystalline silicon film, and a fourth step of activating the fluorine ions. And a fifth step of peeling the oxide film and removing a portion other than a portion of the polycrystalline silicon film in which the fluorine ions are activated to be an active layer to separate elements to form an active layer, A sixth step of forming a gate oxide film on the substrate having an active layer formed thereon, a seventh step of forming a gate electrode on the gate oxide film, and impurity molecules by self-alignment using the gate electrode as a mask. A semiconductor comprising: an eighth step of implanting ions; and a ninth step of forming a contact hole at a predetermined position and forming a source electrode and a drain electrode in the contact hole forming portion. Method of manufacturing location. 5. The method for manufacturing a semiconductor device according to claim 3, wherein the dose of the fluorine ions is such that the fluorine concentration in the active layer is 1 × 10 ¹⁷ cm ⁻³ when the semiconductor device is completed. To 1 × 10 ¹⁹ cm ⁻³ , which is a value within the range.