JPH09171965A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a thin film transistor of high reliability by using a crystalline silicon film which is obtained by a method utilizing a metal element promoting the crystallization of silicon. SOLUTION: A compound of metal elements (such as, nickel acetate solution) which promotes the crystallization of silicon in contact with the surface of an amorphous silicon film 103 is applied thereon. Then, the compound of metal elements is decomposed by irradiation with ultraviolet rays. In addition, heating is carried out by irradiation with infrared rays from a halogen lamp, and heating is carried out under such conditions that the amorphous silicon film 103 is not crystallized. In this heating process, the nickel element is diffused into the amorphous silicon film. Then, the amorphous silicon film 103 is crystallized by heating. Thus, a crystalline silicon film 105 having no local segregation of nickel element and having a uniform crystallinity can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention disclosed in this specification relates to a method for manufacturing a thin film semiconductor device represented by a thin film transistor. In particular, the present invention relates to a method for manufacturing a semiconductor device using a crystalline silicon thin film (crystalline silicon film) formed over a glass substrate or a quartz substrate.

[0002]

2. Description of the Related Art Conventionally, a thin film transistor using a silicon film has been known. This is a technique of forming a thin film transistor by using a silicon film formed on a glass substrate or a quartz substrate.

[0003] Glass substrates and quartz substrates are used for
This is because the thin film transistor is used in an active matrix type liquid crystal display device. Conventionally, a thin film transistor has been formed using an amorphous silicon film. But,
In order to obtain higher performance, it has been attempted to manufacture a thin film transistor using a crystalline silicon film (referred to as a crystalline silicon film).

A thin film transistor using a crystalline silicon film can operate at a high speed of two digits or more as compared with a thin film transistor using an amorphous silicon film. Therefore, the peripheral drive circuit of the active matrix type liquid crystal display device, which has been constituted by the external IC circuit so far, can be formed on the glass substrate or the quartz substrate in the same manner as the active matrix circuit.

Such a structure is very advantageous for downsizing the entire device and simplifying the manufacturing process. Further, the structure leads to a reduction in manufacturing cost.

Generally, a crystalline silicon film is obtained by crystallizing an amorphous silicon film by a plasma CVD method or a low pressure thermal CVD method, followed by heat treatment or laser light irradiation. There is.

However, in the case of heat treatment, the crystallization becomes uneven, and it is difficult to obtain the required crystallinity over a wide area at present.

Although the method of irradiating laser light can partially obtain high crystallinity, it is difficult to obtain a good annealing effect over a wide area. Further, there is a problem that the irradiation of laser light under the condition of obtaining good crystallinity is likely to be unstable.

On the other hand, as a method for obtaining good crystallinity by heat treatment at a lower temperature, the technique described in JP-A-6-232059 is known. This technique is a technique in which a metal element (for example, nickel) that promotes crystallization of silicon is introduced into an amorphous silicon film, and a crystalline silicon film is obtained by heat treatment at a temperature lower than that of the conventional technique.

By using this method, it is possible to obtain a crystalline silicon film which is superior in uniformity over a wider range as compared with the conventional technique.

However, in consideration of practicality, there are improvements such as higher uniformity of crystallinity and a solution to the problem of local segregation of the introduced metal element (silicide is formed).

Especially when the above method is used, there is a problem that the metal element is locally segregated. The region where the metal element is segregated is converted into metal silicide, which is a factor that greatly deteriorates the characteristics as a semiconductor. Further, it becomes a factor of lowering the reliability of the semiconductor device. Specifically, due to this phenomenon, the characteristics of the obtained thin film transistor are likely to vary, and defects are likely to occur.

[0013]

DISCLOSURE OF THE INVENTION The invention disclosed in the present specification relates to the production of a semiconductor device using a crystalline silicon film obtained by utilizing a metal element that promotes crystallization of silicon.
It is an object to improve variations in characteristics and reliability of obtained semiconductor devices.

[0014]

The outline of a typical constitution of the invention disclosed in the present specification is shown below. (There are many other configuration changes, additions, and combinations)

First, a solution (compound of a metal element) containing a metal element that promotes crystallization of silicon is applied onto the amorphous silicon film. Then, irradiation with UV light is performed. The UV light irradiation treats the surface of the amorphous silicon film held in contact with the compound of the metal element. At this time, the metal compound is decomposed by the energy of ultraviolet light.

Then, heat treatment is carried out under the condition that crystallization does not occur. This heat treatment is performed by irradiation with light from a halogen lamp. Alternatively, irradiation is performed with an ultraviolet laser having a wavelength of 380 nm or less.

This step corresponds to a preliminary step of diffusing the metal element before crystallizing the amorphous silicon film into the amorphous silicon film.

The treatment using the above halogen lamp or ultraviolet laser is preferably performed by an automated treatment.

Then, heat treatment is performed to obtain a crystalline silicon film. At this time, a highly uniform crystalline silicon film can be obtained by the action of the metal element that promotes the crystallization of the diffused silicon.

One of the inventions disclosed in this specification is a step of forming an amorphous silicon film on a substrate having an insulating surface, and promoting crystallization of silicon in contact with the surface of the amorphous silicon film. Holding the compound of the metal element, irradiating the surface of the amorphous silicon film with ultraviolet light, and irradiating infrared light or ultraviolet laser to diffuse the metal element into the amorphous silicon film. And a step of crystallizing the amorphous silicon film by heat treatment.

In the above structure, Fe, Co, Ni, Ru, Rh, and P are used as metal elements that promote crystallization of silicon.
An element selected from one or more selected from d, Os, Ir, Pt, Cu, and Au is used. Especially Ni
Is preferable from the viewpoint of its effect and reproducibility.

In the above structure, the metal element is introduced as a compound. Then, the compound of the metal element is decomposed by the irradiation of the ultraviolet light, so that the compound easily diffuses into the amorphous silicon film.

Further, in the above structure, it is important that the step of irradiating infrared light or ultraviolet laser is carried out while maintaining the amorphous property of the amorphous silicon film. That is,
It is important that it is performed under the condition that crystallization of the amorphous silicon film does not proceed.

This is because the purpose of this step is to diffuse the metal element into the amorphous silicon film.

The wavelength of the ultraviolet laser used is 3
It needs to be 80 nm or less. Further, as the infrared rays used, those from a halogen lamp can be used.

According to another aspect of the invention, a step of forming an amorphous silicon film on a substrate having an insulating surface, and a compound of a metal element in contact with the surface of the amorphous silicon film to promote crystallization of silicon And a step of decomposing the compound of the metal element while maintaining the amorphous state of the amorphous silicon film, and a step of maintaining the amorphous state of the amorphous silicon film. A method for manufacturing a semiconductor device, comprising: a step of diffusing a metal element into the amorphous silicon film; and a step of crystallizing the amorphous silicon film by heat treatment.

In the above structure, the decomposition of the compound of the metal element is performed by irradiation with ultraviolet light.

In the above structure, the step of diffusing the metal element into the amorphous silicon film is performed by irradiation of infrared light or ultraviolet laser.

In the above structure, the wavelength of the ultraviolet laser is 380 nm or less.

In the above structure, a halogen lamp is used for the irradiation of infrared rays.

[0031]

[Function] The compound of the metal element is decomposed by performing a treatment by irradiation with ultraviolet light in a state where the compound of the metal element that promotes crystallization of silicon is held in contact with the amorphous silicon film. It is possible to maximize the action of the metal element. Further, since the metal element can be dispersed and introduced into the amorphous silicon film, it is possible to prevent the metal element from being locally segregated later.

By performing a preliminary crystallization process by irradiation with light from a halogen lamp or irradiation with an ultraviolet laser, a metal element that promotes crystallization of silicon should be diffused in the amorphous silicon film in advance. You can By doing so, it is possible to suppress local concentration of the metal element. At this time, it is important to set the condition that the amorphous silicon film is not crystallized. This is because the metal element is locally concentrated in the film as crystallization progresses.

After that, heat treatment is performed to obtain a crystalline silicon film, which has high crystallinity and high uniformity, and the crystallinity in which the metal element is not locally concentrated. A silicon film can be obtained.

[0034]

【Example】

[Embodiment 1] Here, a structure in which a crystalline silicon film is formed over a glass substrate by utilizing the invention disclosed in this specification will be described. FIG. 1 shows a manufacturing process of this embodiment.

First, a silicon oxide film is formed as a base film 102 on a glass substrate (Corning 7059 glass or Corning 1737 glass substrate) 101. Here, a silicon oxide film is formed by a plasma CVD method using silane and TEOS gas. The thickness of the base film is 3000 Å.

As the underlayer film 102, silane and N _{2 are used.}
A film formed by a plasma CVD method using a gas mixed with O 2 gas may be used.

Next, an amorphous silicon film (amorphous silicon film) 103 is formed by the plasma CVD method. The film thickness of the amorphous silicon film 103 is 500 Å. This amorphous silicon film 103 serves as a starting film for a crystalline silicon film to be formed later.

Next, a nickel compound (solution) containing nickel, which is a metal element that promotes crystallization of silicon, is applied. In this embodiment, the nickel element is introduced using a nickel acetate solution having a nickel concentration (wt%) of 10 ppm.

In this case, the amount of nickel element introduced into the amorphous silicon film can be controlled by controlling the content of nickel element in the solution.

After the nickel acetate solution is applied in contact with the surface of the amorphous silicon film 103, spin drying is performed using a spin coater so that the nickel compound is converted into the amorphous silicon film 103 as indicated by 104. Realizes a state of being held in contact with the surface of.

Thus, the state shown in FIG. 1A is obtained. In this state, the surface of the amorphous silicon film is irradiated with ultraviolet light. Then, the nickel compound held in contact with the surface of the amorphous silicon film is decomposed by the energy of the ultraviolet light. (Fig. 1 (B))

Irradiation of ultraviolet light is carried out by using a known ultraviolet light generating means such as a mercury lamp.

Then, infrared light is irradiated from the halogen lamp to heat the amorphous silicon film 103. At this time, it is important to set the condition that the amorphous silicon film is not crystallized. That is, it is important to carry out a preliminary experiment in advance to determine the conditions under which the amorphous silicon film is not crystallized, and to perform this heat treatment under the conditions. (Fig. 1 (C))

In the step shown in FIG. 1C, the nickel element existing in contact with the surface of the amorphous silicon film diffuses into the film.

The heating temperature of the heat treatment for diffusing the nickel element is such that the surface temperature of the amorphous silicon film is 200-200.
It is performed at 450 ° C., preferably 350 ° C. to 400 ° C. It should be noted that even at such a temperature, crystallization may proceed if the heating time is too long.

Next, a heat treatment for crystallizing the amorphous silicon film 103 is performed. By this heat treatment, the amorphous silicon film 103 is crystallized and the crystalline silicon film 105 is obtained. The heat treatment may be performed within a temperature range of 500 ° C to 650 ° C. It is preferable that the heating temperature is as high as possible. However, it is important to set the heating temperature to a temperature below the strain point of the glass substrate that is generally used. this is,
This is for suppressing the deformation of the glass substrate.

Here, in a nitrogen atmosphere, 550
By performing heat treatment at 4 ° C. for 4 hours, the amorphous silicon film 103 is transformed into the crystalline silicon film 105. This heat treatment can be performed at 500 ° C. to the strain point of the glass substrate or lower. The strain point of Corning 7059 glass substrate is 59
It was 3 ° C and the strain point of Corning 1737 glass substrate was 6
67 ° C.

When a quartz substrate is used, the heating temperature can be 800 ° C to 1100 ° C. The heat treatment at such a high temperature is very effective for obtaining higher crystallinity.

The crystallinity of the crystalline silicon film thus obtained was measured by Raman spectroscopy, and the following data were obtained. First, the peak of Raman shift was 518 to 517 cm ^-1 . Also, the half width is 1.
It was 2 to 1.5 times. Moreover, the intensity of Raman shift was equivalent to that of the single crystal silicon wafer.

The above values show that the crystalline silicon film 105 has high crystallinity. Further, it has high uniformity, and the phenomenon in which the nickel element is locally concentrated is largely suppressed.

On the other hand, for comparison, the steps are omitted from FIGS. 1B and 1C, and the amorphous silicon film 103 is crystallized by heat treatment while the nickel compound is present in contact with the surface of the amorphous silicon film 103. A sample was prepared. In this case, it was observed that the obtained crystalline silicon film had an amorphous component scattered therein and that a nickel silicide component was locally present.

The crystalline silicon film produced in the process shown in this embodiment had such a high degree of crystallinity and uniformity as described above.

A thin film transistor was manufactured using the crystalline silicon film obtained according to the process shown in this embodiment. As a result, it was 150 cm ² / N for an N channel type thin film transistor.
Vs, P-channel type thin film transistor 80 cm ² /
The mobility of Vs could be obtained.

Example 2 In this example, instead of the irradiation of infrared light from the halogen lamp in the process shown in Example 1,
An example in which a method using an ultraviolet laser is adopted is shown.

This method utilizes the phenomenon that the surface of the amorphous silicon film is instantaneously heated by the irradiation of the ultraviolet laser. Also in this method, it is important to irradiate the ultraviolet laser under the condition that the amorphous silicon film is not crystallized.

Specifically, the laser irradiation density is 120 to
It is important to carry out the treatment at 220 mJ / cm ^{2 under the} condition that the amorphous silicon film is not crystallized.

As the laser light source, it is preferable to use an excimer type laser light source in terms of its output and cost. Here, a KrF excimer laser (wavelength 248 nm) is used as the ultraviolet laser. The wavelength of this ultraviolet laser is preferably 380 nm or less.

As a practical matter, the lower limit of the wavelength of the ultraviolet laser is limited by the type of gas used. It is also limited by cost and practicality. As the low wavelength excimer laser, Ar ₂ excimer laser (wavelength 126 nm), Kr ₂ excimer laser (wavelength 146 n
m), ArCl excimer laser (wavelength 175n
m), ArF excimer laser (193 nm) is known.

[Embodiment 3] This embodiment shows an example of an irradiation apparatus using a halogen lamp used in the step of diffusing a metal element that promotes crystallization of silicon. FIG. 2 shows an outline of the configuration of the apparatus shown in this embodiment.

In the configuration shown in FIG. 2, the auxiliary chamber 214
A plurality of samples (substrates) arranged in the cassette 215 arranged inside the robot arm 21 in the transfer chamber 211
2 is pulled out through the gate valve 213,
Further, it is transferred into the processing chamber 202 via the gate valve 205.

Then, in the processing chamber 201, the sample (substrate) 210 is irradiated with infrared light from a halogen lamp.
The sample 210 is placed in a closed container 202 made of quartz. The sample 210 is held by the holding means 203.

A cross section taken along the line AA 'in FIG. 2A is shown in FIG. 2B.

Reference numeral 204 is a halogen lamp, and an appropriate inert gas (for example, nitrogen) for cooling the lamp is introduced into the gas introduction system 207 in the space where the halogen lamp exists. Then, unnecessary gas is exhausted from the exhaust system 209.

A suitable inert gas is also introduced into the space in which the sample 210 is placed from the introduction system 206. The unnecessary gas is exhausted from the exhaust system 208. If necessary, the space in which the sample 210 is placed can be depressurized.

The processed sample 210 is transferred by the robot arm 212 arranged in the transfer chamber 211 via the gate valve 205. Then, it is further transferred from the gate valve 213 to the cassette 215 in the preliminary chamber 214.

By repeating the above operation, the sample is continuously processed.

[Embodiment 4] This embodiment shows an example of an ultraviolet laser irradiation apparatus used in the step of diffusing a metal element that promotes crystallization of silicon.

FIG. 3 shows an outline of the apparatus. B in FIG. 3 (A)
A cross section taken along line -B 'is shown in FIG. In the configuration shown in FIG. 3, the same components as those shown in FIG. 2 are the same as those described above.

The structure shown in FIG. 3 irradiates the sample 210 placed on the moving table 302 with laser light. The laser light is oscillated from the laser oscillator 306, and is irradiated on the sample 210 through the optical system 307, the mirror 308, and the quartz window 309.

For irradiation of laser light, the table 302 is on the rail 3
It is performed by scanning by moving on 04. Irradiation with laser light is performed in an airtight chamber 301. If necessary, various gases may be introduced into the gas introduction system 3
It can be introduced from 10. Further, the exhaust system 311 makes it possible to achieve a required reduced pressure state.

Also in the apparatus shown in FIG.
A plurality of samples placed in the cassette 215 therein are successively processed.

[Embodiment 5] This embodiment is an example of forming a CMOS structure with thin film transistors on a glass substrate. 4 to 6 show the manufacturing process of this embodiment.

First, a crystalline silicon film is obtained on the glass substrate 401 according to the structure shown in the first or second embodiment. Then, by patterning it, an active layer 404 of an N-channel type thin film transistor and an active layer 405 of a P-channel type thin film transistor are obtained. Reference numeral 402 is a base film.

After forming the active layers 404 and 405, the silicon oxide film 403 functioning as a gate insulating film is plasma C
The film is formed by the VD method. The thickness is 1000Å.

Thus, the state shown in FIG. 4A is obtained. Here, an example in which a pair of N-channel thin film transistors and P-channel thin film transistors is formed is shown for simplicity of description. Generally, an N-channel type thin film transistor and a P-channel type thin film transistor are formed in units of several hundreds or more on the same glass substrate.

When the state shown in FIG.
As shown in (B), an aluminum film 406 which will later form a gate electrode is formed.

This aluminum film contains scandium in an amount of 0.2 wt% in order to suppress the generation of hillocks and whiskers. The aluminum film is formed by a sputtering method or an electron beam evaporation method.

Hillocks and whiskers are spine-like or needle-like protrusions caused by abnormal growth of aluminum. The presence of hillocks or whiskers causes short circuits or crosstalk between adjacent wirings or between wirings separated by an upper limit.

As a material other than the aluminum film, anodizable metal such as tantalum can be used.

After forming the aluminum film 406, anodization is performed in the electrolytic solution using the aluminum film 406 as an anode to form a thin and dense anodic oxide film 407.

Here, an ethylene glycol solution containing 3% tartaric acid neutralized with ammonia is used as an electrolytic solution. By using this anodizing method, an anodized film having a dense film quality can be obtained. The film thickness can be controlled by the applied voltage.

Here, the thickness of the anodic oxide film 407 is set to 100.
Å The anodic oxide film 407 has a role of improving the adhesiveness with a resist mask formed later. Thus, the state shown in FIG. 4B is obtained.

Next, resist masks 108 and 109 are formed. Then, using the resist masks 408 and 409, the aluminum film 106 and the anodic oxide film 40 on its surface are formed.
7 is patterned. Thus, the state shown in FIG. 1C is obtained.

Next, using 3% oxalic acid aqueous solution as an electrolytic solution, anodic oxidation is carried out with the patterns 410 and 411 made of the aluminum film remaining in this solution as anodes.

In this anodizing step, the anodizing selectively proceeds on the side surfaces of the aluminum films 410 and 411 where the anodization remains. This is aluminum film 410 and 4
11. A dense anodic oxide film and a resist mask 408 on the upper surface of 11.
And 409 remain. (FIG. 4 (D))

In this anodic oxidation, an anodic oxide film having a porous (porous) film quality is formed. Further, this porous anodic oxide film can be grown up to about several μm. (The maximum growth distance of the dense anodic oxide film is about 3000Å)

As a result of this anodic oxidation step, anodic oxide films (anodic oxide rather than films) 412 and 413 are formed.
Here, the progress distance of this anodic oxidation, that is, the film thickness is 700
0 °. The length of the low-concentration impurity region will be determined later by the progress distance of this anodic oxidation. Empirically, it is desirable that the growth distance of this porous anodic oxide film is 6000Å to 8000Å. Thus, the state shown in FIG. 4D is obtained.

In this state, the gate electrodes 11 and 12 are defined. After obtaining the state shown in FIG. 4D, the resist masks 408 and 409 are removed.

Next, anodic oxidation is performed again by using an ethylene glycol solution containing 3% tartaric acid neutralized with ammonia as an electrolytic solution. In this step, the electrolytic solution penetrates into the porous anodic oxide films 412 and 413. As a result, dense anodic oxide films 414 and 415 shown in FIG. 4E are formed.

The thickness of the dense anodic oxide films 414 and 415 is 600 Å. The remaining portion of the dense anodic oxide film 407 previously formed is formed by the anodic oxide films 414 and 415.
Will be integrated with.

In the state shown in FIG. 4E, the entire surface is doped with P (phosphorus) ions as an impurity imparting N type.

This doping is 0.2-5 × 10 ¹⁵ / c
The dose is as high as m ² , preferably 1 to 2 × 10 ¹⁵ / cm ² . A plasma doping method is used as the doping method.

As a result of the step shown in FIG. 4E, regions 416, 417, 418 in which P ions are implanted at a high concentration,
419 is formed.

Next, the porous anodic oxide films 412 and 413 are removed using a mixed acid obtained by mixing acetic acid, nitric acid and phosphorus. In this way, the state is obtained as shown in FIG.

After obtaining the state shown in FIG.
As shown in (B), P ions are implanted again. This P
The dose of ion implantation is 0.1 to 5 × 10 ¹⁴ / cm 3.
² , preferably a low value of 0.3 to 1 × 10 ¹⁴ / cm ² . In this doping, the surface concentration of P is 2
It is set to be not more than × 10 ¹⁹ / cm ³ .

That is, P performed in the step shown in FIG.
The dose of the ion implantation is set lower than the dose performed in the step shown in FIG.

As a result of this step, the regions 421 and 423 are
Further, the regions 426 and 427 are lightly doped low concentration impurity regions. Further, the regions 420 and 424, and further the regions 425 and 428 are high-concentration impurity regions in which P ions are implanted at a higher concentration.

In this step, the region 420 serves as the source region of the N-channel type thin film transistor. And 421 and 423 become a low concentration impurity region. Again 424
Becomes the drain region. Further, the region indicated by 423 is a region generally called an LDD (lightly doped drain) region.

Next, as shown in FIG. 5C, a resist mask 429 which covers the N-channel thin film transistor is arranged.

In the state shown in FIG. 5C, B (boron) ion implantation is performed. Here, the dose amount of B ions is 0.2 to 10 × 10 ¹⁵ / cm ² , preferably 1 to 2 ×.
It is about 10 ¹⁵ / cm ² . This dose is shown in Fig. 4 (E).
The dose can be set to be approximately the same as that in the step shown in FIG.

In this step, the conductivity types of the regions 425 and 426, and 427 and 428 are inverted from N type to P type.

Thus, the source region 430 and the drain region 432 of the P-channel type thin film transistor are formed. Further, the region 431 is a channel forming region without any impurities being implanted. (FIG. 5 (C))

Before implanting B ions, regions 426 and 427 in FIG. 5B are N ⁻ -type low-concentration impurity regions in which P ions are implanted at a low concentration. Therefore, the conductivity type is easily reversed by the implantation of B ions.

In particular, the junction with the channel forming region 431 is easily inverted from the NI junction to the PI junction. That is, the required junction can be easily formed.

Therefore, 426 and 42 with the same dose amount as the P ion implantation step in the step of FIG.
The conductivity type of the region 7 can be reversed to form P-type impurity regions 430 and 432.

Since the dose amount can be reduced as compared with the case of reversing the normal conductivity type, it is possible to prevent the resist mask from being deteriorated by the implantation of the impurity ions.

After the step shown in FIG. 5C is completed, the resist mask 429 is removed to obtain the state shown in FIG. In this state, laser light irradiation is performed to activate the implanted impurities and anneal the regions where the impurity ions are implanted.

At this time, a region shown by a pair of source / drain regions 420 and 424 of the N-channel type thin film transistor and a region shown by a set of source / drain regions 430 and 432 of the P-channel type thin film transistor. Irradiation with laser light can be performed in a state in which the difference in crystallinity between and is not so large.

The difference in crystallinity is not so large because extreme heavy doping is not performed in the step shown in FIG. 5 (C).

Therefore, when laser light irradiation is performed in the state shown in FIG. 5D to anneal the source / drain regions of the two thin film transistors, the difference in annealing effect can be corrected.

As a result, the difference in the characteristics of the obtained N-type and P-channel type thin film transistors can be corrected.

After obtaining the state shown in FIG.
An interlayer insulating film 133 is formed as shown in FIG. The interlayer insulating film 133 is composed of a 4000-Å thick silicon nitride film.
A plasma CVD method is used as a method for forming the silicon nitride film.

Next, contact holes are formed to form a source electrode 434 and a drain electrode 435 of an N-channel type thin film transistor (NTFT). At the same time, the source electrode 4 of the P-channel type thin film transistor (PTFT)
37 and the drain electrode 436 are formed. (Fig. 6 (B))

Here, patterning is performed so as to connect the drain electrode 435 of the N-channel type thin film transistor and the drain electrode 436 of the P-channel type thin film transistor, and the gate electrodes of the two TFTs are connected to each other to realize a CMOS structure. To be done.

In the structure having the CMOS structure shown in FIG. 6B, the low-concentration impurity regions 421 and 423 are arranged toward the N-channel type thin film transistor.

The low-concentration impurity regions 421 and 423 reduce the OFF current. -Prevent deterioration of TFT due to hot carriers. -Increases the resistance between the source / drain and reduces the mobility of the NTFT. It has such an action.

Generally, when a CMOS structure as shown in FIG. 6B is used, a difference in characteristics between the N-channel type thin film transistor and the P-channel type thin film transistor becomes a problem.

For example, when the crystalline silicon film as in this embodiment is used, the mobility of the N-channel type thin film transistor is about 100 to 150 Vs / cm ² .
The mobility of a P-channel thin film transistor is 30 to 80.
Only Vs / cm ² can be obtained.

Further, the N-channel type thin film transistor has a problem of deterioration due to hot carriers. This problem does not occur particularly in the P-channel type thin film transistor.

In general, a CMOS circuit does not require a low OFF current characteristic.

In such a situation, the following significance can be obtained by arranging the low concentration impurity regions 421 and 423 on the N-type thin film transistor side.

That is, in the CMOS structure, by lowering the mobility of the N-type thin film transistor and preventing its deterioration, the overall characteristic balance with the P-channel type thin film transistor is taken, and the characteristic as a CMOS circuit is obtained. Can be improved.

In the process shown in this embodiment, the process shown in FIG.
It is important that the active layer is covered with the silicon oxide film 403 forming the gate insulating film in the step of implanting the impurity ions shown in (E), FIG. 5 (B) and FIG. 5 (C).

By implanting impurity ions in such a state, it is possible to suppress the surface of the active layer from being roughened or contaminated. This greatly contributes to improving the yield and the reliability of the obtained device.

The CMOS type thin film circuit shown in this embodiment is
It can be used for an active matrix type liquid crystal display device and an active matrix type EL display device.

[Embodiment 6] This embodiment shows an example in which the crystalline silicon film obtained in the process of Embodiment 1 is further irradiated with laser light to promote its crystallinity.

When the crystalline silicon film crystallized by the heat treatment in the process shown in Example 1 is further irradiated with laser light, its crystallinity can be promoted. Then, a crystalline silicon film having higher crystallinity can be obtained.

As the laser light in this case, it is preferable to use an excimer laser having an ultraviolet region.

[0129]

By utilizing the invention disclosed in this specification, a thin film semiconductor device having high reliability can be obtained. In particular, in the manufacture of a semiconductor device using a crystalline silicon film obtained by utilizing a metal element that promotes crystallization of silicon, it is possible to improve variations in the characteristics of the obtained semiconductor device and reliability.

[Brief description of the drawings]

1A to 1C show steps of manufacturing a crystalline silicon film.

FIG. 2 shows an outline of a processing apparatus using a halogen lamp.

FIG. 3 shows an outline of a processing apparatus using an ultraviolet laser.

FIG. 4 shows a manufacturing process of a complementary thin film transistor.

FIG. 5 shows a manufacturing process of a thin film transistor configured to be complementary.

FIG. 6 shows a manufacturing process of a complementary thin film transistor.

[Explanation of symbols]

 101 glass substrate 102 base film (silicon oxide film) 103 amorphous silicon film 104 nickel compound 105 crystalline silicon film

Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location H01L 21/336

Claims (13)

[Claims] 1. A step of forming an amorphous silicon film on a substrate having an insulating surface, and a step of holding a compound of a metal element in contact with the surface of the amorphous silicon film to promote crystallization of silicon. Irradiating the surface of the amorphous silicon film with ultraviolet light; irradiating infrared light or ultraviolet laser to diffuse the metal element into the amorphous silicon film; A method of manufacturing a semiconductor device, comprising: a step of crystallizing a high quality silicon film; 2. The metal element for promoting crystallization of silicon according to claim 1, wherein Fe, Co,
Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu, A
A method for manufacturing a semiconductor device, wherein one or more elements selected from u are used. 3. The method for manufacturing a semiconductor device according to claim 1, wherein the compound of the metal element is decomposed by irradiation with ultraviolet light. 4. The method for manufacturing a semiconductor device according to claim 1, wherein the step of irradiating with an infrared light or an ultraviolet laser is performed in a state in which the amorphousness of the amorphous silicon film is maintained. 5. The infrared light or ultraviolet laser irradiation according to claim 1, wherein the amorphous silicon film is maintained in an amorphous state, and the infrared light or ultraviolet laser irradiation causes the amorphous silicon film to be amorphous. A method for manufacturing a semiconductor device, wherein the metal element is diffused in a silicon film. 6. The method for manufacturing a semiconductor device according to claim 1, wherein the wavelength of the ultraviolet laser is 380 nm or less. 7. The method of manufacturing a semiconductor device according to claim 1, wherein a halogen lamp is used for the irradiation of infrared rays. 8. A step of forming an amorphous silicon film on a substrate having an insulating surface, and a step of holding a compound of a metal element in contact with the surface of the amorphous silicon film to promote crystallization of silicon. A step of decomposing the compound of the metal element while maintaining the amorphous state of the amorphous silicon film; A method of manufacturing a semiconductor device, comprising: a step of diffusing into a crystalline silicon film; and a step of crystallizing the amorphous silicon film by heat treatment. 9. The metal element according to claim 8, wherein Fe, Co,
Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu, A
A method of manufacturing a semiconductor device, wherein an element selected from one or more selected from u is used. 10. The method for manufacturing a semiconductor device according to claim 8, wherein the decomposition of the compound of the metal element is performed by irradiation with ultraviolet light. 11. The method for manufacturing a semiconductor device according to claim 8, wherein the step of diffusing the metal element into the amorphous silicon film is performed by irradiation with infrared light or ultraviolet laser. 12. The method of manufacturing a semiconductor device according to claim 8, wherein the wavelength of the ultraviolet laser is 380 nm or less. 13. A method for manufacturing a semiconductor device according to claim 8, wherein a halogen lamp is used for irradiation of infrared rays.