JPH0778759A - Method and device of manufacturing semiconductor material - Google Patents

Abstract

PURPOSE:To enable semiconductor material to be improved in reproducibility and enhanced in characteristics by a method wherein the semiconductor material is continu ously subjected to laser annealing under vacuum without breaking vacuum when a film is formed. CONSTITUTION:A substrate 20 is set in a first preparatory chamber 201, and the preparatory chamber 201 is heated and exhausted. Then, a first chamber 203 is exhausted, a substrate 202 is transferred from the preparatory chamber 201 to the first chamber 203, and a film is formed through sputtering for the formation of a substrate 204. Next, a second preparatory chamber 206 is exhausted, and the substrate 204 is transferred from the first chamber 203 to the preparatory chamber 206. Furthermore, a second chamber 208 is exhausted, a substrate 207 is transferred from the preparatory chamber 206 to the second chamber 208, and a film is formed for the formation of a substrate. Then, a third preparatory chamber 209 is exhausted, and the substrate is transferred from the second chamber 208 to the third preparatory chamber 209. A substrate 211 is irradiated with excimer laser ray 212 through a window 210 provided to the third preparatory chamber 209 to execute a laser annealing process. Thereafter, the third preparatory chamber 209 is made to return to an atmospheric pressure, and then the substrate 211 is taken out of the chamber 209.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor element manufacturing method and manufacturing apparatus. The present invention relates to a manufacturing apparatus for the purpose of improving the characteristics of a semiconductor material and providing a semiconductor device having the characteristics improved by utilizing the semiconductor material according to the present invention.

[0002]

2. Description of the Related Art Conventionally, it has been known that an amorphous semiconductor material is produced in a semiconductor manufacturing process. For example, an amorphous semiconductor film or a surface in an amorphous state was obtained by film formation by a low temperature sputtering method or a chemical vapor deposition method (CVD method) or high energy ion irradiation. Note that in this specification, the term "amorphous" does not mean purely disorder at the atomic level, but is also used to include a substance in which short-range order of several nm exists. Specifically, it means a silicon material having an electron mobility of 10 cm ² / V · s or less, or a material having a carrier mobility of 1% or less of the essential carrier mobility of the semiconductor material.

Since an amorphous semiconductor (amorphous silicon, amorphous germanium, etc.) has a remarkably small carrier mobility (electron mobility or hole mobility), it is used as it is, for example, in a thin film transistor (TF).
T) is rarely used as a channel forming region or an impurity region such as a source or a drain, and these amorphous semiconductor materials are usually used after being crystallized at a temperature of 400 ° C. or higher. However, such thermal crystallization requires a heat treatment for a long time if the temperature is to be lowered, and a high temperature treatment if it is used for a short time treatment. In a process that has limitations such as heat resistance and mass productivity of a substrate, a low temperature and short time treatment is desired, but this is a problem that cannot be solved by a conventional thermal method.

In recent years, a method has been developed in which an amorphous film or surface is irradiated with intense light such as laser light or xenon lamp light to transform it into a crystalline semiconductor material to improve its carrier mobility. Was done. (In the following text, this method is called "laser annealing", but it does not necessarily have to use a laser. It also includes the case of irradiating a powerful flash lamp as well as laser light irradiation. In this method, the substantial temperature of the substrate can be kept at 400 ° C. or lower, the processing time is short, and mass productivity is excellent.

[0005]

However, it has been difficult to obtain a semiconductor material having excellent characteristics (for example, a semiconductor material having high mobility) with good reproducibility by the laser annealing method. And the cause is simply attributed to the variation in laser energy, and no drastic solution has been known. The present invention shows a method for improving the reproducibility and providing a semiconductor material that is stable and has good characteristics, and further shows a manufacturing method (processing method) superior in mass productivity as compared with the conventional method.

[0006]

The inventor of the present invention has thought that the presence of foreign elements such as oxygen, nitrogen and carbon in the film is one of the causes of the instability of laser annealing. Then, they have found that a semiconductor having high mobility can be obtained by performing laser annealing using a pure semiconductor material (silicon or germanium) having such an extremely small amount of foreign elements as a raw material film.

However, it is difficult to obtain good characteristics with good reproducibility. The cause is that oxygen gas, nitrogen gas, water, carbon dioxide, etc. contained in the atmosphere of the film during the laser annealing are taken into the film or adsorbed on the film surface by the laser annealing. It was presumed that it might be incorporated into the membrane during the treatment.

A special fabrication method is required to avoid this difficulty. That is, it is necessary to devise such that the production / formation of the amorphous film / surface and the laser annealing process are continuously performed, and during that period, no contact with the outside air is made. For that purpose, it is necessary to connect a vacuum processing apparatus such as a film forming apparatus or an ion implantation apparatus to a laser annealing apparatus so that the sample can be continuously operated without being taken out.

Further, when performing such continuous processing, it is apparent that the productivity may be improved as compared with the case where the sample is taken out from each vacuum processing apparatus and laser annealing is performed. became.

In addition to the above, it is needless to say that the laser annealing conditions must be optimized in order to obtain high carrier mobility. The conditions of the laser annealing differ depending on the laser oscillation conditions (continuous oscillation or pulse oscillation, repetition frequency, intensity, wavelength, film, etc.) and cannot be generally stated. As the laser, an ultraviolet laser such as an excimer laser and a visible or infrared laser such as a YAG laser can be used, and it is necessary to select the laser according to the thickness of the film to be laser annealed. That is, in general, in a silicon or germanium material, since the absorption length for ultraviolet rays is short, laser light does not reach a deep portion, and laser annealing occurs only in a relatively shallow region of the surface. On the other hand, the absorption length for visible light and infrared light is long, and the light penetrates relatively inside,
Therefore, the laser annealing also occurs in the deep portion. Hereinafter, the present invention will be described in more detail with reference to examples.

[0011]

【Example】

Example 1 A TFT having a planar structure was produced and its electrical characteristics were evaluated. First, using a film forming apparatus having two chambers, an amorphous silicon film having a thickness of about 100 nm and a silicon nitride film having a thickness of 10 nm thereon are formed on a quartz substrate coated with a silicon nitride film having a thickness of 10 nm. It was formed continuously. The amorphous silicon film was formed by a normal sputtering method, and the silicon nitride film was formed by a glow discharge plasma CVD method. The film forming apparatus and the laser annealing apparatus shown in FIG. 2 were used.

First, the substrate 202 is set in the first preliminary chamber 201, the preliminary chamber is heated to 200 ° C., the chamber is evacuated, and the pressure in the preliminary chamber is set to 10 ⁻⁶ torr or less.
Held for hours. Next, except for film formation, it is always 10 ^-4 torr
The first chamber 203, which is maintained below r and is controlled so that outside air does not enter, is evacuated to 10 ⁻⁶ torr and the substrate is moved from the preliminary chamber 201 to the first chamber 20.
3, the substrate is set, and the substrate 204 and the target 20 are set.
While keeping 5 at 200 ° C., it was evacuated and kept for 1 hour under the condition that the chamber pressure was 10 ⁻⁶ torr or less.
Then, argon gas was introduced into the chamber, RF plasma was generated, and sputtering film formation was performed. As the sputtering target 205, a silicon target having a purity of 99.9999% or higher is used and 1 ppm of phosphorus is contained. The substrate temperature during film formation was 150 ° C., the atmosphere was substantially 100% argon, and the pressure was 5 × 10 ^-2 torr. No hydrogen or other gases were intentionally added to the argon. The concentration of argon was 99.9999% or more. Input power is 200W, RF frequency is 13.56
It was MHz.

After the film formation, the RF discharge was stopped, and the first chamber 203 was evacuated to 10 ^-6 torr. Then, the second auxiliary chamber 206, which is always kept at 10 ^-5 torr or less and is provided between the first chamber 203 and the second chamber 208, is evacuated to 10 ^-6 torr, and the first chamber is evacuated. The substrate was transferred from 203 to the second preliminary chamber 206. Furthermore, except when forming a film, it is always 10 ⁻⁴ to
The second chamber 208, which is maintained below rr and is controlled so that outside air does not enter, is exhausted to 10 ⁻⁶ torr,
The substrate 207 is moved from the second preliminary chamber 206 and set in the second chamber 208, and the substrate 209 is set to 20.
While maintaining the temperature at 0 ° C., the chamber was evacuated and the chamber pressure was maintained at 10 ⁻⁶ torr or less for 1 hour.

Ammonia gas having a purity of 99.9999% or more and disilane gas (Si ₂ H ₆ ) diluted with hydrogen are introduced into the second chamber 208 at a ratio of 3: 2, and the total pressure is 10 ^-1. It was set to torr. Then, an RF current was introduced into the chamber to generate plasma and deposit silicon nitride. Input power (13.56 MH
z) was 200W.

After the film formation, the RF discharge was stopped, and the second chamber 208 was evacuated to 10 ^-6 torr. Then, a third preliminary chamber 209 provided on one side of the second chamber 208 and having a quartz window 210 is set at 10 ⁻⁶ torr.
The substrate was transferred from the second chamber 208 to the third auxiliary chamber 209 by vacuum evacuation to. Then, the excimer laser light 212 is passed through the window 210 of the third preliminary chamber to the substrate 2
After 11 irradiation, laser annealing was performed.

As described in this embodiment, the method of continuously performing the laser annealing without breaking the vacuum state from the film-forming state in this way is the present embodiment. It was extremely effective even when a protective film such as the silicon nitride film was formed, or even when no protective film was formed.
The reason for this is that not only the material that becomes the nucleus of crystal growth, such as dust, is attached or scratched on the film, there is no adsorption of moisture or gas, and the vacuum state is changed to the atmospheric pressure state. It is thought that this is because there was no small change in the film surface, no protrusion, etc. due to the non-uniform stress of the film.

When the film formation and the laser annealing are continuously performed in this way, a film formation chamber and a preliminary chamber are provided as in this embodiment, and a laser is provided by providing a window in the preliminary chamber (for example, 209). An annealing method and a method of providing a window in the film formation chamber and performing laser annealing after the film formation in the film formation chamber can be considered, but the latter always adheres to the window because the window becomes cloudy due to film formation. Whereas the coating must be etched, the former does not. Therefore, it can be said that the former method is superior in consideration of mass productivity and maintainability.

After the laser annealing was completed in the third auxiliary chamber 209, dry nitrogen gas was introduced into the third auxiliary chamber 209 to bring it to atmospheric pressure, and the substrate was taken out. And
After the silicon nitride film is removed by a known dry etching method, the silicon film is removed by 100 μm × as shown in FIG.
The island-shaped rectangle 102 of 500 μm was etched. 1
01 is a substrate.

The oxygen, nitrogen and carbon concentrations of this coating are all 10 ¹⁶ cm ^-3 or less, which means that another coating produced in the same step is treated by secondary ion mass spectrometry (SIMS).
Confirmed by analyzing by.

Further, a gate insulating film 103 having a thickness of about 100 nm was formed by a sputtering method in an oxygen atmosphere.
At this time, the substrate temperature is 150 ° C., RF (13.56 MH)
z) The input power was 400W. The sputtering target was silicon oxide having a purity of 99.9999% or higher.
The atmosphere was essentially oxygen and no other gases were intentionally added. The oxygen concentration was 99.999% or more. The pressure was 5 × 10 ^-2 torr.

After that, an aluminum film (thickness 200 n
m) was formed by a known vacuum evaporation method, and unnecessary portions were removed by a known dry etching method to form a gate electrode 104. The width of the gate electrode was 100 μm. At this time, the photoresist 105 used for dry etching was left on the gate electrode.

Then, by ion implantation, boroso ions were implanted at 10 ¹⁴ cm ^-2 except for the gate electrode portion. Under the gate electrode, the gate electrode and the photoresist thereabove serve as a mask, and borosoions are not implanted. By this step, the impurity regions, that is, the source region 106 and the drain region 107 were formed in the silicon film.

Further, the whole substrate is placed in a vacuum container and 10
Laser annealing was performed by irradiating the back surface of the substrate with excimer laser light at a pressure of ^-5 torr. By this step, the amorphous silicon film in the impurity region which was made amorphous by the ion implantation step was crystallized.

In this method, the second laser annealing for activating the source and drain regions is performed not from the front surface of the substrate but from the back surface thereof, so that the impurity regions 106 and 107 and the channel formation region are continuously connected. You can make a connection.

Next, thermal annealing was performed in a hydrogen atmosphere. Place the substrate in a chamber that can be evacuated,
It was once evacuated to 10 ⁻⁶ torr by a turbo molecular pump and further heated to 100 ° C. After maintaining this state for 30 minutes, hydrogen gas with a purity of 99.99% or more is
It is introduced into the chamber up to 0 torr and the substrate is heated to 300 ° C.
Annealed for 60 minutes. Here, the vacuum evacuation is performed once in order to remove gas, moisture, etc. adsorbed on the coating. When thermal annealing is performed with these remaining,
It was empirically known that high mobility cannot be obtained with good reproducibility.

Finally, holes were formed in the silicon oxide film (thickness 100 nm) existing on the source region and the drain region, and aluminum electrodes 108 and 109 were formed in these regions. Through the above steps, a thin film field effect transistor was formed.

100 field effect transistors were prepared and their IV characteristics were measured. As a result, the electron mobility in the channel formation region was 275 cm ² / Vs on average. In addition, the threshold voltage (threshold voltage)
The average was 4.2V. The average drain current ratio was 8 × 10 ⁶ . Reference value of electron mobility is 100c
m ² / Vs, the threshold voltage reference value is 5.0
Set the reference value of V / drain current ratio to 1 × 10 ⁶ , and
When 0 pass / fail transistors were checked for pass / fail, 81 pass.

[Example 2] A TFT having a planar structure was prepared and its electrical characteristics were evaluated. First, using a film forming apparatus having two chambers as in Example 3, a thickness of about 1
00nm amorphous silicon film and thickness 1 on it
A 0 nm silicon nitride coating and a 10 nm thick silicon nitride coating were successively formed on a quartz substrate.
The amorphous silicon film is
Further, the silicon nitride film was formed by glow discharge plasma CVD method. The device used was that shown in FIG.

First, the substrate is set in the first preliminary chamber 201, the preliminary chamber is heated and evacuated, and the pressure in the preliminary chamber is set to 10 ^-6.
It was kept for 1 hour under the condition of torr or less. Next, the first chamber 203 is evacuated to 10 ⁻⁶ torr, the substrate is moved from the preliminary chamber 201, the substrate is set in the first chamber 203, and the substrate and the target are heated and evacuated to evacuate the chamber. The pressure was maintained at 10 ^-6 torr or less for 1 hour. Then, argon gas was introduced into the chamber, RF plasma was generated, and sputtering film formation was performed.

After the film formation was completed, the RF discharge was stopped and the first chamber 203 was evacuated. Then, the second auxiliary chamber 206 provided between the first chamber 203 and the second chamber 208 is evacuated to evacuate the first chamber 2
The substrate was transferred from 03 to the second preliminary chamber 206. Further, the second chamber 208 is evacuated, and the second auxiliary chamber 2
The substrate was moved from 06 to set it in the second chamber 208, the substrate was heated and evacuated, and the chamber pressure was held at 10 ⁻⁶ torr or less for 1 hour.

Ammonia gas and disilane gas (Si ₂ H ₆ ) are introduced into the second chamber 208,
The total pressure was 10 ^-1 torr. Then, an RF current was introduced into the chamber to generate plasma and deposit silicon nitride. Input power (13.56MHz) is 2
It was 00W.

After the film formation, the RF discharge was stopped and the second chamber 208 was evacuated. Then, a third chamber provided on one side of the second chamber 208 and having a quartz window 210 is provided.
Of the second chamber 208.
The substrate was transferred to the third preliminary chamber 209 from. Then, an argon gas having a purity of 99.9999% or more was introduced into the third auxiliary chamber 209, and the internal pressure was set to 5 atm. And
Laser annealing was performed by irradiating the excimer laser beam 212 through the window 210 of the third preliminary chamber.

As described above, the method of continuously performing the laser annealing from the film-forming state without touching the outside air is as follows.
As shown in this embodiment, even when the protective film is formed on the amorphous semiconductor film,
It was extremely effective even when the protective film was not formed. It is considered that the reason is that a material such as dust that serves as a nucleus for crystal growth does not adhere to or scratch the film. Further, as in the case of the present embodiment, laser annealing in a pressurized atmosphere has the effect of suppressing the generation of microscopic bubble rows in the coating due to laser irradiation and preventing the deterioration of characteristics.

[0034]

According to the present invention, a semiconductor material having high reproducibility and high mobility was obtained. In the present invention, the laser annealing of the semiconductor film formed mainly on the insulating substrate has been described, but the material of the substrate may be a single crystal semiconductor such as a single crystal silicon substrate used in a monolithic IC or the like. .

Although the silicon film is described in the embodiments, the present invention can be applied to a germanium film, a silicon-germanium alloy film, other intrinsic semiconductor material or compound semiconductor material. Can be applied. As mentioned earlier, in the present specification, it is described that a method called laser annealing is used as a method for improving the mobility of an amorphous film. However, this expression includes a method in which a laser is not used, such as flash lamp annealing. is there. That is, the present invention relates to a method of improving crystallinity of a semiconductor material by utilizing strong optical energy.

[Brief description of drawings]

FIG. 1 shows a manufacturing process of a thin film transistor.

FIG. 2 shows a vacuum processing apparatus used for manufacturing a thin film transistor.

[Explanation of symbols]

 101 ... Substrate 102 ... Semiconductor coating 103 ... Insulator coating 104 ... Gate electrode 105 ... Photoresist 106 ... Source region 107 ... Drain region 108 ... Source electrode 109 ... ..Drain electrode 201 ... First preliminary chamber 202 ... Substrate 203 ... First chamber 204 ... Substrate 205 ... Target 206 ... Second preliminary chamber 207 ... Substrate 208 ... Second chamber 209 ... Third preparatory chamber 210 ... Quartz window 211 ... Substrate 212 ... Excimer laser light 213 ... Gas introduction system 214 ... Exhaust system 215 ... RF power supply

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location H01L 29/786 21/336 (72) Inventor Yasuhiko Takemura 398 Hase, Atsugi, Kanagawa Prefecture Semiconductor Energy Research Institute

Claims (2)

[Claims] 1. A semiconductor manufacturing apparatus having at least two vacuum processing chambers, wherein one chamber is a chamber for laser annealing, and the processing is performed in at least one vacuum processing chamber among other vacuum processing chambers. A semiconductor material manufacturing apparatus, wherein the received substrate is transferred to a laser annealing chamber and laser-annealed. 2. A method of forming a semiconductor material on a substrate, characterized in that after film formation in a film formation chamber, the substrate is transferred to another chamber and then laser annealed without being exposed to the outside air. Manufacturing method of semiconductor material.