JP3484547B2 - Thin film formation method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film semiconductor used in a large image pickup device / driving device such as an office automation equipment, a display device / driving device, a high speed integrated circuit, a micro object feeding mechanism, and a micromechanics such as an ink jet. The present invention relates to a thin film forming method for forming a film.

[0002]

2. Description of the Related Art In recent years, a scanning circuit portion of an image reading apparatus such as an elongated one-dimensional photosensor or a large-area two-dimensional photosensor, a liquid crystal (LC), an electrochromic material (EC), or electroluminescence. With the increase in the size of these devices, it has been proposed to use a thin film transistor in a drive circuit portion of an image display device using a material (EL). A thin film transistor is formed by using a silicon thin film formed on a predetermined substrate as a material.Since a silicon thin film is relatively easily formed on a large area substrate, conventionally, a silicon thin film used for forming a thin film transistor is amorphous. Silicon or polycrystalline silicon thin films are often used.

However, in recent years, the demand for higher speed and higher functionality for these devices has increased, and along with this, it has become necessary to improve the performance of the thin film transistor of the driving section. The mobility of a thin film transistor formed of a polycrystalline silicon thin film is 0.1 to 1.0 cm ² / V for an amorphous silicon thin film transistor.
- it is about sec, also a 1.0~10cm ² / V · about sec polycrystalline silicon thin film transistor, about 600cm about ² / V · sec which is the mobility of the transistor formed using a single crystal silicon It is far below. Therefore, there is an increasing demand for forming a single crystal silicon thin film on a large area substrate.

By the way, as a thin film forming method for forming a single crystal semiconductor thin film, plasma CVD method, thermal CVD method, optical CVD method, LPCVD method, MOCVD method, sputtering method,
Methods such as vacuum deposition are generally known, but the crystal structure of the thin film obtained by any of the methods is similar to the crystal structure of the substrate. Therefore, even if a thin film is formed by the above-described thin film forming method on a conventionally used amorphous insulating substrate such as glass or ceramic, a single crystal thin film cannot be obtained. Becomes polycrystalline or amorphous.

Therefore, this polycrystalline or amorphous thin film,
For example, once a thin silicon film has been melted into a strip,
A method of converting this into a single crystal thin film by recrystallization [zone melting recrystallization method, ZoneMelt Recrystallizatio
n (ZMR method)] has been proposed. In the ZMR method, it is known that the surface orientation becomes (100) orientation by adjusting the conditions, but defects called subgrain boundary are likely to occur in the crystal thin film, and in order to improve the crystallinity and orientation. Seed crystals are often used. When the single crystal silicon thin film only needs to be on an insulator, as in the case of high-speed devices, high-power devices, etc., use a silicon wafer with an oxide film as a supporting substrate, and use it as a part of the oxide film. A single crystal silicon thin film can be formed by forming a hole and using the lower silicon wafer as a seed crystal.

[0006]

However, it is difficult to use a seed crystal when an optically transparent substrate is required as in the case of application to an image device or the like.
Also, from the viewpoint of effectively utilizing resources, most of the crystallized rods of the silicon wafer are scraped off by the time the wafer has the wafer shape. Therefore, it has been desired to establish a technique for directly forming a good single crystal silicon thin film on a mechanical supporting substrate.

An object of the present invention is to provide a thin film forming method capable of forming a thin film having good crystallinity on a substrate without using a seed crystal.

It is another object of the present invention to provide a thin film forming method capable of forming a thin film having good crystallinity on a large area substrate without using a seed crystal.

Another object of the present invention is to provide a thin film forming method capable of forming a thin film having good crystallinity on a substrate without using a seed crystal and controlling its plane orientation and in-plane crystal direction. To provide.

Further, an object of the present invention is to form a thin film capable of forming a thin film having good crystallinity on structures having various sample conditions by controlling the plane orientation and the in-plane crystal direction. To provide a method.

[0011]

In the thin film forming method of the present invention, as shown in FIG. 1, a polycrystalline or amorphous semiconductor layer (semiconductor thin film) 70 formed on a predetermined substrate 701 is formed.
2 and the surface protection layer 70 formed on the semiconductor layer 702.
3, the semiconductor layer 702 is melted in a band shape by heating a part of the structure body 700 in a band shape, and the band-shaped melted region is orthogonal to the longitudinal direction of the band-shaped melted region. The semiconductor layer 702 is recrystallized by moving in the direction, so that the semiconductor layer 702 is converted into a single crystal semiconductor layer over a wide region.
In this specification, the terms "semiconductor layer" and "semiconductor thin film" are used as the same meaning, that is, as a synonym.

As described above, also in the present invention, the zone melting recrystallization method (ZMR method) is used to obtain a single crystal semiconductor thin film, and in this case, the present invention uses the crystal in the initial stage of the step of the ZMR method. The growth is controlled to be facet growth, and the control is performed so that a specific crystal axis of the crystal is oriented in the moving direction of the heating region, and thereafter, the control is performed so that the growth mode of crystal growth is transferred to cellular growth. It has become. In order to perform such control, in the present invention, the thermal gradient from the melt state to the solid state of the semiconductor (that is, the temperature gradient between the solid phase and the liquid phase) is set at the beginning of the process of the ZMR method (that is, the crystal growth). (In the early stage of), as the crystal growth progresses,
This thermal gradient (temperature gradient) is made gentle so that the crystal growth mode is controlled. That is, ZM
At the beginning of the process of the R method, the thermal gradient is made steep (large) to perform facet growth, and control is performed so that a specific crystal axis of the crystal is oriented in the moving direction of the heating region. A crystal with few defects is obtained by changing the growth mode of the crystal growth to a cell-like growth by making it small (small).

It is generally known that the crystal growth mode of the thin film semiconductor in the ZMR method is facet growth or cell-like growth, and these two crystal growth modes are either mixed or not mixed depending on the crystal growth conditions. Appears. Even if the crystal growth mode is facet growth or cellular growth, by adjusting the growth conditions,
It is known that the plane orientation of the recrystallized thin film can be (100) orientation.

In the facet growth mode, as shown in FIG. 2, the boundary between the solid phase and the liquid phase is a specific crystal face 101, and the facet of such a specific crystal face is called a facet face. ing. For example, in a crystal having a diamond structure such as silicon or germanium, facet plane 101
Is known to be the {111} plane. In the single crystal thin film grown by such a facet growth mode, as shown by reference numeral 102 in FIG. 2 and enlarged in FIG. 3, a sub-grain boundary is formed. It is known to have a defect called.

As a result of investigating the crystal growth related to the present invention, such a subgrain boundary 102 is generated as a result of the existence of the competitive relationship of the growth of facets during the melt recrystallization. As long as it is in the facet growth mode, it has been revealed that it is difficult to avoid it by suppressing the artificial disturbance of heat during melt recrystallization. In other words, the subgrain boundary generated by the facet growth of such a thin film can be physically interpreted as a kind of strong-coupling nonlinear evolution phenomenon that repeats generation and disappearance, and the "fluctuation" can be suppressed artificially. Is impossible in principle. Further, in the case of facet growth, since the growth in the direction of a specific crystal axis is fast, a crystal thin film recrystallized from the initial stage of crystal growth often has a certain specific crystal axis. Even if crystals having different growth directions are mixed in the crystallized crystal thin film, a specific crystal axis is aligned with the crystal having the growth direction as the crystal growth progresses. For example, in a crystal having a diamond structure such as silicon or germanium, such a crystal axis is a [100] axis, and by performing crystal growth in facet growth mode, a single crystal thin film after recrystallization has a It was found that a (100) oriented film having [100] axes aligned in the growth direction, that is, the moving direction of the band-shaped heating was obtained.

On the other hand, in the cell-like growth mode, as shown in FIG. 4, the boundary between the solid phase and the liquid phase does not become a specific crystal plane, but is constituted by a curved surface as indicated by reference numeral 301. There is. Further, in the recrystallized thin film grown by the cell growth mode, defects found in the thin film are linear as shown by reference numeral 302 in FIG. 4 and enlarged in FIG. 6 is a locus of defects, or is a set of point defects arranged on a straight line as indicated by reference numeral 302 'in FIG. 6, the occurrence of defects is sparse, and the intervals are wide. Things are known. This differs from faceted growth mode in cellular growth mode,
This is because there is no growth competition between the cells, and the interface shape between the solid phase and the liquid phase during growth is maintained long and stable during growth.

However, when the crystal growth was examined in connection with the present invention, it was difficult to control the growth direction in the cellular growth mode because it did not have a specific crystal plane with a high growth rate. In addition, even if crystals with different growth directions were mixed in the recrystallized film, it was clarified that crystals with different growth directions were never culled because there was no competition between cells. FIG. 7 is a diagram for explaining this situation. From FIG. 7, it is understood that in the cell-like growth, the crystal growth directions cannot be controlled, and crystals C ₁ and C ₂ having different growth directions can be formed. In addition, in FIG.
Reference numeral 601 is a linear defect, reference numeral 602 is an etch pit formed to evaluate the crystal, and the diagonal line of the square is the [100] axis.

These two crystal growth modes occur because a trace amount of impurities are mixed into the semiconductor during melt recrystallization, a compositionally supercooled state occurs, and the solid-liquid interface does not become a flat surface. Is known to do. For example, in the structure 700 shown in FIG. 1, when quartz glass (SiO ₂ ) is used as the support substrate 701, silicon is used as the thin film semiconductor layer 702, and silicon oxide (SiO ₂ ) is used as the surface protection layer 703, the melting is performed. Oxygen in silicon during recrystallization affects the generation of the crystal growth mode.
It is known that the two crystal growth modes are facet growth when the temperature gradient from the liquid layer to the solid phase is steep, and are cell-like growth when the temperature gradient is gentle.

Based on such knowledge, in the present invention, in order to form a thin film having good crystallinity, the crystal is facet-grown at the initial stage of the ZMR process and then the cell-like growth is performed. In order to perform such growth, the present invention uses (ie,
At the initial stage of crystal growth), the thermal gradient from the melt state to the solid state of the semiconductor (temperature gradient of solid phase / liquid phase) is made steep, and then the temperature gradient is made gentle.

To make the temperature gradient between the solid phase and the liquid phase steep,
For example, a region in which heat escape is large may be provided in the portion of the structure where melt recrystallization is first performed by the ZMR method. In this case, the temperature gradient between the solid phase and the liquid phase can be made steep in this portion of the structure, and the semiconductor in this portion can be facet-grown. For this purpose, for example, a cooling layer may be provided.

According to the method described above, that is, the method of the present invention, the substrate 701 that does not become the seed crystal of the semiconductor layer 702 to be recrystallized can be used. Note that the substrate 701 has a melting point higher than that of the semiconductor. Specifically, as the substrate 701, an amorphous substrate made of a simple substance such as quartz glass, a single element single crystal wafer such as a silicon wafer or a germanium wafer, or SiC, BN, BP, BAs, AlP, AlS.
b, GaP, GaAs, GaSb, InP, InAs,
InSb, ZnS, ZnTe, CdS, CdSe, Cd
On the compound semiconductor wafer of Te, CdHg, etc., SiO ₂ ,
A material having an amorphous insulating film such as SiON formed thereon (without using the underlying crystal layer as a seed crystal) can be used.

Further, in the present invention, since a single crystal thin film is obtained by utilizing the recrystallization phenomenon of the thin film, a wide range of semiconductor materials can be used for the semiconductor layer 702. Specifically, single element semiconductors such as Si and Ge, and Si
C, BN, BP, BAs, AlP, AlSb, GaP,
GaAs, GaSb, InP, InAs, InSb, Z
nS, ZnTe, CdS, CdSe, CdTe, CdH
A compound semiconductor such as g can be used.

As the surface protective layer 703, a material which does not become a seed crystal of the semiconductor layer 702 to be recrystallized and whose melting point is higher than that of the semiconductor can be used. Specifically, for example, an amorphous insulating film such as SiO ₂ or SiON can be used.

As the cooling layer, any layer may be used as long as it has a function of increasing the escape of heat from the melt recrystallization region as compared with the region where this layer is not provided. There is one that utilizes the increase in the heat and one that actively dissipates the heat to the outside. Specifically, in the former case, an amorphous insulating film such as SiO ₂ or SiON is used as a cooling layer, and in the latter case, a refractory metal, ethylene glycol or the like can be used.

For example, when quartz glass is used for the substrate 701 and silicon is used for the semiconductor layer 702, the surface protective layer 70 is used.
SiO ₂ can be used as 3, and SiON can be used as a cooling layer at this time. Regarding the escape of heat during melt recrystallization, there is no problem with the type of strip heating source, but in the sense that the controllability of the heating pattern is good, an energy beam such as a laser or electron beam is used as a strip heating source. desirable.

In the above example, the temperature gradient is made steep by providing the cooling layer, but in order to make the temperature gradient of the solid phase / liquid phase steep, this is controlled by controlling the moving speed of the strip heating region. It can also be realized. For example, rapid heating and quenching can be performed by increasing the moving speed of the band-shaped heating region at the initial stage of the ZMR process, and the temperature gradient of the solid phase / liquid phase in this portion can be made steep.

Alternatively, the flexibility of shaping the heat pattern of the energy beam is utilized to make the temperature gradient of the solid phase / liquid phase in the band-shaped heating region steep at the beginning of the ZMR process, and thereafter make the temperature gradient gentle. Is also possible. In this case, a laser beam or an electron beam can be used as the energy beam.

Further, the fact that the laser beam is absorbed only by a specific substance according to the absorption coefficient is utilized to make the semiconductor layer 7
A first laser for heating the periphery of 02 and the semiconductor layer 702
By using a second laser that selectively heats the laser, the functional separation of the heating source is realized, and by increasing the output of the second laser in the early stage of the ZMR process, the solid phase and
It is also possible to make the temperature gradient of the liquid phase steep. For example, as in the above example, quartz glass is used for the substrate 701, silicon is used for the semiconductor layer 702, and the surface protection layer 70 is used.
When SiO ₂ is used as 3, it is possible to use a carbon dioxide gas laser as the first laser and an Ar laser as the second laser.

As described above, in the present invention, the crystal is facet-grown at the initial stage of the ZMR process, control is performed so that the crystal faces a specific crystal axis, and then the cell-like growth is performed. Therefore, a semiconductor thin film having good crystallinity can be formed on the substrate 701 without using a seed crystal.

That is, in the initial stage of the ZMR process, solid phase
Crystals are facet-grown with a steep temperature gradient in the liquid phase, and then cells are grown with a gentle temperature gradient between the solid and liquid phases to align a specific crystal axis in the moving direction of the heating region. A crystal with few defects can be obtained.

However, even in this case, there may be many defects due to thermal disturbance during the ZMR process,
When using a semiconductor thin film after recrystallization, depending on the position of such a defect, it may hinder the production of a good device. In order to avoid such a problem, it is necessary to further control the crystal growth direction and control the defect generation position.

Therefore, in the present invention, as the surface protective layer 703, one having a thick band-shaped region and a thin film-shaped region along the longitudinal direction of the heating region is used. Alternatively, laser light is used as a heating source, and antireflection films for laser light are formed on the surface protective layer 703 at predetermined intervals along the longitudinal direction of the heating region.

Note that these methods are called sweeping or entrainment. This method controls the position where crystallization is finally performed by providing a region in which a large amount of heat is input and a region in which a smaller amount of heat is input along the longitudinal direction of the band-shaped heating region. Therefore, as shown in FIG. 8, it is intended to control the generation position of the defect 801. However, with this method alone, when the seed crystal is not used, the crystal growth direction cannot be controlled as shown in FIG. 9, and crystals C ₃ and C ₄ with different growth directions can be formed across the sweeping section. There is also.
In FIG. 9, reference numeral 901 is a linear defect, reference numeral 902 is an etch pit formed to evaluate a crystal, and the diagonal line of the square is the [100] axis.

Therefore, in the present invention, in addition to such an entrainment technique, a steep temperature gradient between the solid phase and the liquid phase is further provided at the initial stage of the ZMR process, so that this portion is facet-grown and the crystal orientation Controllable.

Further, in order to realize stable crystal growth in the ZMR process, it is important to secure a stable heat source as well as a stable heat source. When the ZMR process is performed in an open air atmosphere, heat escapes from the upper surface of the structure 700 by heat transfer, but heat transfer by natural convection is very unstable.

Therefore, in the present invention, the ZMR process is further carried out, for example, under a reduced pressure atmosphere. This allows the top surface of the structure 700 to be in a heat-insulated state,
Stable melt recrystallization is possible.

Alternatively, the ZMR process can be performed in an inert gas atmosphere. Here, the inert gas is a gas that does not cause a chemical change in the structure 700 during melt recrystallization, and specifically, Ar gas.
An inert element gas such as gas or N ₂ gas can be used.
Furthermore, air may be blown from the horizontal direction of the structure 700 during the step of melt recrystallization under an inert atmosphere. By blowing air, heat escape from the upper surface of the structure 700 is set as a forced convection heat transfer condition, and stable melt recrystallization can be performed.

FIG. 10 is a diagram showing a structural example of a thin film manufacturing apparatus used in the thin film forming method of the present invention. Referring to FIG. 10, this thin film manufacturing apparatus has an energy beam generation source 3002 as a heating source for heating a structure 700 installed in a chamber 3001, and an energy beam generated from the energy beam generation source 3002 into strips. Energy beam optical system and focusing system 3003 capable of shaping, focusing, and varying the focusing width, and energy beam scanning capable of moving the heating region during the process of melt recrystallization and changing the moving speed thereof. Output of energy beam from optical system 3005 and energy beam generation source 3002, energy beam optical system and focusing system 3003
A control mechanism 3006 for independently controlling the beam scanning optical system 3005 and a blower mechanism 3007 are included.

The energy beam scanning optical system 300
A structure moving mechanism 3008 for moving the structure 700 may be provided instead of or together with the structure 5. In this case, the control mechanism 3006 controls the structure moving mechanism 3008 instead of or together with the beam scanning optical system 3005. Note that when both the beam scanning optical system 3005 and the structure moving mechanism 3008 are controlled to move, the moving speed of the structure 700 can be increased. Further, an exhaust mechanism may be provided instead of or in addition to the blower mechanism 3007.

Here, the chamber 3001 has a structure capable of ensuring stable melt recrystallization during the ZMR process.

Further, the energy beam generating source 300
A beam generation source for emitting a charged particle beam such as an electron beam or an ion beam or a laser beam is used as 2. As the energy beam generation source 3002,
It is desirable that the output can be controlled in the range of 2 to 3 digits, but if the output range cannot be widened in the range of 2 to 3 digits, such as in the case of a laser, a cylindrical lens is used to increase the power density to 2 to 3. Be able to secure 3 digits.

As the energy beam optical system and the focusing system 3003, one having a function of forming an energy beam into a band is used. Specifically, in the case of a charged particle beam, a Q lens and an electrostatic deflection system are used. In the case of a laser beam, an optical system including a mirror for laser synthesis, a beam combiner and a cylindrical lens for beam focusing is used.

Further, the energy beam scanning optical system 300
5 or the structure moving mechanism 3008 is one having a function of moving the band-shaped heating region relative to the structure 700. Specifically, as the energy beam scanning optical system 3005, In the case of a charged particle beam, an electrostatic deflection system or the like can be used, and in the case of a laser beam, a rotating mirror or the like can be used.

The structure moving mechanism 3008 has a function of relatively moving the heating region by moving the structure 700 itself, and the moving speed of the heating region with respect to the structure 700 is 2 to 3. It is desirable to be able to control in the range of digits.

Further, the control mechanism 3006 changes the power density by changing the energy beam output and the energy beam convergence during the ZMR process, and also changes the energy beam scanning optical speed or the structure moving speed during the process. By changing the moving speed of the heating region according to the above, or by changing both the power density and the moving speed, the one that controls the growth mode of the crystal growth during the ZMR process is used.

By using this thin film manufacturing apparatus, the crystal growth mode is controlled by making the temperature gradient of the solid phase / liquid phase steep at the initial stage of crystal growth, which is the feature of the present invention, and then making the temperature gradient gentle. However, it is possible under a wide range of wafer conditions. As a result, in the present invention, a thin film with good crystallinity can be formed on a large area substrate without using a seed crystal.

FIG. 11 shows a configuration example using the above-mentioned first laser and second laser as the energy beam generating source (heating source 3002). Figure 1
In the first example, for example, 12 carbon dioxide gas lasers are used as the first laser 2507, eight Ar lasers are used as the second laser 2508, and the carbon dioxide gas laser beam from the carbon dioxide gas laser 2507 is used as the mirror 250.
9 to the structure 700, and an Ar laser beam from the Ar laser is emitted to the cylindrical lens 25.
11, the structure 700 is irradiated through the mirror 2510. Note that, in FIG. 11, for convenience, 12 carbon dioxide lasers and 8 Ar lasers are shown as one respectively. Also, 12 carbon dioxide laser beams from 12 carbon dioxide lasers and 8
Each of the eight Ar laser beams from the two Ar lasers corresponds to the corresponding mirror 2509, 251.
0, it is synthesized by the beam combiner and is incident on the structure 700 as a synthesized laser beam.
Each synthetic laser beam is represented by one straight line. The outputs of the lasers 2507 and 2508 are controlled by the control mechanism 3006.

The synthesized carbon dioxide laser beam and Ar laser beam are superposed on the structure 700 by the mirrors 2509 and 2510. The Ar laser beam is a converging system cylindrical lens 2511.
It is uniaxially squeezed by passing through. Further, the position of the cylindrical lens 2511 can be moved under the control of the control mechanism 3006.

Further, the angles of the mirrors 2509 and 2510 can be adjusted by the control of the control mechanism 3006, and the beam irradiation position on the structure 700 can be moved.

[0050]

EXAMPLES Examples of the present invention will be described in detail below. Example 1 In Example 1, basically, first, a structure 700 as shown in FIG. 1 was produced. That is, the support substrate 701
For this, a quartz glass wafer having a diameter of 100 mm and a thickness of 500 μm is used, and after cleaning the support substrate 701 by a cleaning method such as the RCA method which is usually used in the manufacturing process of semiconductor devices, the support substrate 701 is depressurized onto the support substrate 701. Chemical vapor deposition (LP
A polycrystalline silicon layer having a thickness of 0.33 μm was formed as a semiconductor layer 702 by a CVD method. After that, cleaning was performed, and a silicon oxide layer was formed to a thickness of 1.3 μm as a surface protective layer 703 by a low pressure chemical vapor deposition method (LPCVD method).

Here, a SiH ₄ + N ₂ O system was used as a source gas, and a film was formed at a film forming temperature of 750 ° C. After that, 95
Annealing is performed in a furnace at 0 ° C., and then the thickness of the surface protective layer in the portion where the melt recrystallization is first performed is smaller than the thickness of other portions of the surface protective layer by a photolithography method that is usually performed. Surface protection layer 7 so that it becomes thick
The other part of 03 was etched. 12 and 13 are a plan view and a sectional view of the structure manufactured in this way. Note that FIG. 13 is a sectional view taken along the line AA of FIG. In Example 1, as shown in FIGS. 12 and 13, specifically, the thickness of the region 1001 of the surface protective layer 703 at the portion where the melt recrystallization is first performed is 1.3 μm.
Then, the remaining region 1002 of the surface protective layer 703 was etched to have a thickness of 0.5 μm .

Then, using the thin film manufacturing apparatus as shown in FIG. 14, ZMR is applied to the structure 700 formed as described above.
The process was carried out. In practice, an Ar laser is used as a heating source (energy beam generation source) 3002, and a heater mechanism 1203 is provided above and below a stage 1204 for supporting the structure 700 in the chamber 3001, and the heater mechanism 1203 is provided above the stage 1204. To structure 700
To support the vacuum pump 120 inside the chamber 3001.
After depressurizing at 2, during the ZMR process in the chamber 700,
The atmosphere was Ar gas and the pressure was 133.3 Pa . In addition, prior to performing the ZMR process, the heater mechanism 12
03, the structure 700 is preheated, and the structure 700
A bias temperature of 1100 ° C. was applied to.

Then, the structure 700 was irradiated with a laser beam from an Ar laser. Here, the laser beam from the Ar laser has a beam diameter of 1.5 mm immediately after it is emitted from the heating source 3002, but it is linearly combined by the energy beam optical system and the converging system 3003 as shown in FIG. It was converged and used as a synthetic Ar laser beam. That is, the beam was expanded ten times with a beam expander to have a diameter of 15 mm, and the laser beam having a diameter of 15 mm was linearly combined and used as shown in FIG. 15 using eight beam combiners. This linearly synthesized laser beam was converged by a cylindrical lens having a focal length of 800 mm and used as a linear heating source.
This beam was moved by the beam scanning optical system 3005 at a moving speed of 1.0 mm / s. That is, the structure 700
Area 1 where the thickness of the surface protective layer 703 is 1.3 μm.
The layer was sequentially moved in the direction indicated by arrow R ₁ from the 001 side toward the region 1002 having a thickness of 0.5 μm . Ar at this time
The output of the laser was 6 W each. By this heating source, a region of the semiconductor layer 702 having a width of about 60 mm can be recrystallized at one time, but by performing this twice, the entire region of the semiconductor layer 702 of the structure 700 can be melted and recrystallized. Whole area of the semiconductor layer 702 at one time (at one time)
When melt recrystallization is desired, the number of laser beams may be further increased.

As a result of carrying out the melt recrystallization in this way, the defects in the semiconductor layer 702 become as shown in FIG. 3 in the portion where the film thickness of the silicon oxide layer which is the surface protection layer 703 is 1.3 μm. Further, in the portion where the film thickness is 0.5 μm , it becomes as shown in FIG. Further, in the transition region between these two portions, defects as shown in FIG. 16 were confirmed. In FIG. 16, reference numeral 1402 is a linear defect, and reference numeral 1401 is a subgrain boundary.

Example 2 In Example 2, the support substrate 701 has a diameter of 100 mm,
After using a quartz glass wafer having a thickness of 500 μm and washing the supporting substrate 701 by a cleaning method such as the RCA method which is usually used in the manufacturing process of semiconductor devices, the supporting substrate 70 is cleaned.
A polycrystalline silicon layer 702 having a thickness of 0.33 μm is formed as a semiconductor layer 702 on the substrate 1 by low pressure chemical vapor deposition (LPCVD method).
The film was formed to a film thickness of m . After that, cleaning is performed and the surface protection layer 703 is formed by the low pressure chemical vapor deposition method (LPCVD method).
As a result, a silicon oxide layer was formed to a thickness of 0.5 μm .

Here, a SiH ₄ + N ₂ O system was used as a source gas, and a film was formed at a film forming temperature of 750 ° C. After that, 95
Annealing was performed in a furnace at 0 ° C. Then, a SiON layer 1604 having a thickness of 1.5 μm was formed as a cooling layer by an ion beam sputtering method. Then, by a commonly used photolithography technique, the cooling layer was left only in the portion where the melt recrystallization was performed first, and the remaining portion was removed by etching. 17 and 18 are a plan view and a sectional view of the structure manufactured in this way. Note that FIG. 18 is a sectional view taken along the line BB of FIG.

The heating method of the ZMR method and the moving method of the heating region are the same as those in the first embodiment, and the strip-shaped heating region is indicated by the arrow R _2.
Were sequentially moved in the directions indicated by. In the case of this example as well,
Similar to the above, defects in the semiconductor film subjected to melt recrystallization are
In the portion where the cooling layer 1604 is present, it becomes as shown in FIG.
In addition, the cooling layer 1604 is omitted and only the surface protective layer 703 is formed as shown in FIG.

In the above example, the case where the heating source is a laser has been described, but in Examples 1 and 2, since the escape of heat is ensured in the structure of the structure, the strip heater and the electronic Other heating sources such as beams are also possible.

Example 3 In Example 3, the support substrate 701 has a diameter of 100 mm,
After using a quartz glass wafer having a thickness of 500 μm and washing the supporting substrate 701 by a cleaning method such as the RCA method which is usually used in the manufacturing process of semiconductor devices, the supporting substrate 70 is cleaned.
A polycrystalline silicon layer 702 having a thickness of 0.33 μm is formed as a semiconductor layer 702 on the substrate 1 by low pressure chemical vapor deposition (LPCVD method).
The film was formed to a film thickness of m . After that, cleaning is performed and the surface protection layer 703 is formed by the low pressure chemical vapor deposition method (LPCVD method).
As a result, a silicon oxide layer was formed to a thickness of 0.5 μm .

Here, a SiH ₄ + N ₂ O system was used as a source gas, and a film was formed at a film forming temperature of 750 ° C. After that, 95
Annealing was performed in a furnace at 0 ° C.

Next, Z is added to the structure formed as described above.
An MR process was performed. As the heating source, as in Example 1,
A synthetic Ar laser beam is used, and the chamber 30 is used.
Preheating by the heater mechanism 1203 in 01 is also 110
The temperature was set to 0 ° C.

The initial moving speed of the heating source during the ZMR process was set to 10 mm / s, and the output of the Ar laser in the initial section was set to 50 W per line accordingly. After that, the moving speed of the heating source was set to 10 mm / s, and accordingly, the output of the Ar laser was set to 6 W per one.

In the case of this example, as in the case of Example 1, the defects in the semiconductor film subjected to the melt recrystallization are as shown in FIG. Then it looks like Figure 5.

Example 4 In Example 4, the support substrate 701 had a diameter of 100 mm,
After using a quartz glass wafer having a thickness of 500 μm and washing the supporting substrate 701 by a cleaning method such as the RCA method which is usually used in the manufacturing process of semiconductor devices, the supporting substrate 70 is cleaned.
A polycrystalline silicon layer was formed as a semiconductor layer 702 on the substrate 1 by a low pressure chemical vapor deposition method (LPCVD method) to a film thickness of 0.33 μm. After that, cleaning was performed, and a silicon oxide layer was formed to a thickness of 0.5 μm as a surface protection layer 703 by a low pressure chemical vapor deposition method (LPCVD method). Here, a SiH ₄ + N ₂ O system was used as a source gas, and a film was formed at a film forming temperature of 750 ° C. After that, annealing in a furnace was performed at 950 ° C.

Then, the structure 70 formed as described above.
0 to ZMR process. As in Example 1, a synthetic Ar laser beam was used as the heating source, and preheating by the heater mechanism 1203 in the chamber 3001 was set to a temperature of 1100 ° C.

The cylindrical lens used for focusing the Ar laser beam has a focal length of 500 mm.
The moving speed of the heating source formed by the synthetic Ar laser beam was 3.0 mm / s. At the beginning of the ZMR process, the cylindrical lens used for converging the Ar laser beam was kept in a just focus state, and the output thereof was set to 8 W each. After this, set the cylindrical lens 150m from the just focus position.
After shifting by m, they were put into an off-focus state, and accordingly, the output power per laser was set to 20W.

In the case of this example as well, as in Example 1, the defects in the semiconductor film subjected to the melt recrystallization are as shown in FIG. 3 in the portion where the melt recrystallization was performed first, and the regions thereafter. Then it looks like Figure 5.

In the above-mentioned example, the case where the heating source is a laser is described, but the fourth embodiment utilizes the flexibility and convergence of the pattern formation of the energy beam, and charged particles such as an electron beam are used. Beams can also be used.

Example 5 In Example 5, the support substrate 701 has a diameter of 100 mm,
After using a quartz glass wafer having a thickness of 500 μm and washing the supporting substrate 701 by a cleaning method such as the RCA method which is usually used in the manufacturing process of semiconductor devices, the supporting substrate 70 is cleaned.
A polycrystalline silicon layer was formed as a semiconductor layer 702 on the substrate 1 by a low pressure chemical vapor deposition method (LPCVD method) to a film thickness of 0.33 μm. After that, cleaning was performed, and a silicon oxide layer was formed to a thickness of 0.5 μm as a surface protection layer 703 by a low pressure chemical vapor deposition method (LPCVD method). Here, a SiH ₄ + N ₂ O system was used as a source gas, and a film was formed at a film forming temperature of 750 ° C. After that, annealing in a furnace was performed at 950 ° C.

Then, in the thin film manufacturing apparatus of FIG. 14, the optical system as shown in FIG. 11 was used as a heating source, and the ZMR process was performed on the structure 700 formed as described above. Here, the method of synthesizing the laser beam from the Ar laser that is the second laser 2508 is the same as that in the first embodiment, and the cylindrical lens 2511 has a focal length of 800 mm.
I used the one with just focus. As the carbon dioxide gas laser which is the first laser 2507, 12 laser beams having a laser beam diameter of 9.0 mm at the laser emission end were used, and these laser beams were used as shown in FIG. 19 using a beam combiner. Synthesized.

The synthetic Ar laser beam and the synthetic carbon dioxide gas laser beam thus obtained were superposed in a positional relationship as shown in FIG. In FIG. 20, reference numeral 1801 is a synthetic carbon dioxide laser beam, and reference numeral 1802 is a synthetic Ar laser beam. The two synthetic laser beams as described above were used as a linear heating source and were moved on the structure 700 from the ends thereof at a moving speed of 3.0 mm / s. The preset temperature of the heater mechanism 1203 was set to 500 ° C.

At the beginning of the ZMR process, the Ar laser 2 is used.
The output of 508 was set to 20W per line, and with this,
The output of each carbon dioxide gas laser 2507 was set to 8 W. After that, the output of the Ar laser 2508 was set to 6 W per line, and accordingly, the output of the carbon dioxide gas laser 2507 was set to 13 W per line.

In the case of this example, the defects in the semiconductor film subjected to the melt recrystallization are as shown in FIG. 3 at the portion where the film thickness of the surface protective layer is 1.3 μm, and the film thickness of the surface protective layer is 0. .5μ
In the part of m , it became like FIG. Further, in the transition region between the two parts, defects were confirmed as shown in FIG.

Example 6 In Example 6, the support substrate 701 has a diameter of 100 mm,
After using a quartz glass wafer having a thickness of 500 μm and washing the supporting substrate 701 by a cleaning method such as the RCA method which is usually used in the manufacturing process of semiconductor devices, the supporting substrate 70 is cleaned.
A polycrystalline silicon layer was formed as a semiconductor layer 702 on the substrate 1 by a low pressure chemical vapor deposition method (LPCVD method) to a film thickness of 0.33 μm. After that, cleaning was performed, and a silicon oxide layer was formed to a thickness of 1.3 μm as a surface protective layer 703 by a low pressure chemical vapor deposition method (LPCVD method). Here, a SiH ₄ + N ₂ O system was used as a source gas, and a film was formed at a film forming temperature of 750 ° C. After that, annealing in a furnace was performed at 950 ° C.

After that, the thickness of the surface protective layer in the portion where the melt recrystallization is first performed is made thicker than the thickness of the other portion of the surface protective layer by a commonly used photolithography technique. The surface protection layer 703 was also etched so that the other portions of the surface protection layer had different thicknesses at predetermined intervals. 21 and 2
2 is a plan view and a cross-sectional view of the structure manufactured in this way. Note that FIG. 21 is a cross-sectional view taken along the line DD of FIG. In Example 6, as shown in FIG. 21, the thickness of the region 1001 of the surface protective layer 703 at the portion where the melt recrystallization is first performed is 1.3 μm, and the region 1002 of the surface protective layer 703 downstream thereof is 100 μm. Then, as shown in FIG. 22, a portion having a width of 100 μm along the longitudinal direction Z of the heating region has a thickness of 0.6 μm, and a portion having a width of 10 μm between the portions having a width of 100 μm has a thickness of 0.3 μm . did.

The heating method of the ZMR method and the moving method of the heating region are the same as those in the first embodiment, and the strip-shaped heating region is indicated by the arrow R _3.
Were sequentially moved in the directions indicated by. In the case of this example, the defects in the semiconductor film subjected to the melt recrystallization are as shown in FIG. 3 in the portion where the film thickness of the surface protective layer which is first subjected to the melt recrystallization is 1.3 μm. As shown in FIG. 5 on the downstream side of the melt recrystallization, the defect generation position was swept away from the portion where the film thickness of the surface protective layer was 0.6 μm .
The film thickness of the surface protective layer was concentrated in the area of 0.3 μm .

Example 7 In Example 7, the support substrate 701 had a diameter of 100 mm,
After using a quartz glass wafer having a thickness of 500 μm and washing the supporting substrate 701 by a cleaning method such as the RCA method which is usually used in the manufacturing process of semiconductor devices, the supporting substrate 70 is cleaned.
A polycrystalline silicon layer was formed as a semiconductor layer 702 on the substrate 1 by a low pressure chemical vapor deposition method (LPCVD method) to a film thickness of 0.33 μm. After that, cleaning was performed, and a silicon oxide layer was formed to a thickness of 0.6 μm as a surface protective layer 703 by a low pressure chemical vapor deposition method (LPCVD method). Here, a SiH ₄ + N ₂ O system was used as a source gas, and a film was formed at a film forming temperature of 750 ° C. After that, annealing in a furnace was performed at 950 ° C.

After that, the surface protection layer is etched by a commonly used photolithography technique, and a portion having a width of 100 μm is thickened along the longitudinal direction Z of the heating region in the same manner as shown in FIG. It is a 0.6 .mu.m, the thickness of the portion of 10μm width between parts of the 100μm width is 0.3 [mu] m.

The heating method of the ZMR method and the moving method of the heating region were the same as those in Example 3. In the case of this example, the defects in the semiconductor film subjected to the melt recrystallization are as shown in FIG. 5 except for the region where the melt recrystallization was performed first, as in the case of the seventh embodiment. The occurrence position of was swept away from the portion where the film thickness of the surface protective layer was 0.6 μm , and was concentrated in the portion where the film thickness of the surface protective layer was 0.3 μm .

In the example described here, the heating method and the heating region moving method are the same as those in the third embodiment, but of course, the same result can be obtained by using the method in the fourth embodiment.

Example 8 In Example 8, the support substrate 701 had a diameter of 100 mm,
After using a quartz glass wafer having a thickness of 500 μm and washing the supporting substrate 701 by a cleaning method such as the RCA method which is usually used in the manufacturing process of semiconductor devices, the supporting substrate 70 is cleaned.
A polycrystalline silicon layer was formed as a semiconductor layer 702 on the substrate 1 by a low pressure chemical vapor deposition method (LPCVD method) to a film thickness of 0.33 μm. After that, cleaning was performed, and a silicon oxide layer was formed as the surface protection layer 703 to a thickness of 0.55 μm by the low pressure chemical vapor deposition method (LPCVD method). Here, a SiH ₄ + N ₂ O system was used as a source gas, and a film was formed at a film forming temperature of 750 ° C. After that, annealing in a furnace was performed at 950 ° C.

Next, Si which becomes the antireflection film of the laser is formed.
The N film 2104 was formed to a thickness of 0.07 μm by the LPCVD method. After that, the SiN film is etched by a commonly used photolithography technique, and the SiN film 2104 is removed from a portion having a width of 100 μm along the longitudinal direction Z of the heating region, as shown in FIG. Then, the SiN film 2104 is left only in the 10 μm wide portion between the 100 μm wide portions.

The heating method of the ZMR method and the method of moving the heating region were the same as in Example 1. In the case of this example, the defects in the semiconductor film subjected to the melt recrystallization are as shown in FIG. 5 except for the region where the melt recrystallization was performed first, as in the case of the seventh embodiment. The generation position of was swept away from the portion where the SiN film 2104 of the antireflection film was not provided, and was concentrated on the portion where the SiN film 2104 exists.

Example 9 In Example 9, the support substrate 701 has a diameter of 100 mm,
After using a quartz glass wafer having a thickness of 500 μm and washing the supporting substrate 701 by a cleaning method such as the RCA method which is usually used in the manufacturing process of semiconductor devices, the supporting substrate 70 is cleaned.
A polycrystalline silicon layer was formed as a semiconductor layer 702 on the substrate 1 by a low pressure chemical vapor deposition method (LPCVD method) to a film thickness of 0.33 μm. After that, cleaning was performed, and a silicon oxide layer was formed to a thickness of 1.3 μm as a surface protective layer 703 by a low pressure chemical vapor deposition method (LPCVD method). Here, a SiH ₄ + N ₂ O system was used as a source gas, and a film was formed at a film forming temperature of 750 ° C. After that, annealing in a furnace was performed at 950 ° C.

After this, as shown in FIG. 24, only the region 1001 of the surface protective layer 703 at the portion where the melt recrystallization is first performed is made to have a thickness of 1.3 μm by a commonly used photolithography technique. , The thickness of the remaining portion 1002 of the surface protective layer 703 by etching
It was 0.55 μm . Then, a SiN film 2304 to be a laser antireflection film is formed by LPCVD to 0.07 μm.
Then , the SiN film 2304 is etched by a photolithography method that is usually performed, and the surface protection layer of silicon oxide has a thickness of 0.55 μm.
25, the SiN film 2304 is removed along the longitudinal direction Z of the heating region (that is, along the line E-E of FIG. 24) on the region of 100 μm, as shown in FIG.
The 10 μm wide portion between the 100 μm wide portions is made of Si.
The N film 2304 was left.

The heating method of the ZMR method and the moving method of the heating region are the same as those in Example 5, and the strip-shaped heating region is indicated by an arrow R _4.
It moved in order as shown by. In the case of this example, the defects in the semiconductor film subjected to the melt recrystallization are as shown in FIG. 5 except for the region where the melt recrystallization was performed first, as in the case of Example 8. The generation position of was swept away from the portion where the SiN film 2304 of the antireflection film was not provided, and was concentrated on the portion where the SiN film 2304 exists.

Example 10 In Example 10, a thin film manufacturing apparatus as shown in FIG. 26 was used. That is, in the thin film manufacturing apparatus of FIG. 14, a thin film manufacturing apparatus in which a blower mechanism 3007 was further provided on the side of the structure 700 was used. Conditions of structure 700 and Z
The heating method of the MR method and the moving method of the heating region were the same as in Example 9. However, the atmosphere was Ar gas atmosphere and atmospheric pressure. Also, because this atmosphere is different,
The output of the carbon dioxide gas laser 2507 was 23 W each.

In the case of this example, the defects in the semiconductor film subjected to the melt recrystallization are as shown in FIG. 5, except for the region where the melt recrystallization was performed first, as in the case of the eighth embodiment. ,
The position where the defect occurs is the SiN film 2304 of the antireflection film.
The particles were swept from the portion where the SiN film 2304 is not provided and concentrated on the portion where the SiN film 2304 exists.

[0089]

As described above, according to the present invention, the growth direction can be controlled on an amorphous substrate without using a seed crystal, that is, the crystal can be formed in accordance with a specific direction of the structure. A good single crystal semiconductor thin film that can be grown and has few defects can be obtained.
As a result, when the present invention is applied to a device, improvement of device characteristics, reduction of variations in characteristic values, improvement of yield, etc. can be achieved.

Further, in the present invention, an energy beam having a good controllability of the heat pattern is used as a heat source, and the moving speed of the heat source and the power density of the heat source are controlled, so that the sample (structure)
A good single crystal semiconductor thin film with few defects can be obtained regardless of the conditions.

[Brief description of drawings]

FIG. 1 is a diagram showing a structural example of a structure used in a thin film forming method of the present invention.

FIG. 2 is a diagram for explaining a facet growth mode.

FIG. 3 is a partially enlarged view of FIG.

FIG. 4 is a diagram for explaining a cellular growth mode.

FIG. 5 is a partially enlarged view of FIG.

FIG. 6 is a diagram showing an example of defects generated in a recrystallized thin film grown in a cell growth mode.

FIG. 7 is a diagram for explaining a state of recrystallization in a cell-like growth mode.

FIG. 8 is a diagram for explaining a method of controlling a defect generation position.

FIG. 9 is a diagram for explaining a drawback of the method shown in FIG.

FIG. 10 is a diagram showing a configuration example of a thin film manufacturing apparatus used in the thin film forming method of the present invention.

FIG. 11 is a diagram showing a configuration example of an energy beam generation source.

12 is a plan view of the structure used in Example 1. FIG.

FIG. 13 is a cross-sectional view of a structure used in Example 1.

FIG. 14 is a diagram showing a configuration example of a thin film manufacturing apparatus.

FIG. 15 is a diagram showing a synthetic Ar laser beam.

16 is a diagram showing a state of a recrystallized thin film obtained by the method of Example 1. FIG.

17 is a plan view of a structure used in Example 2. FIG.

FIG. 18 is a cross-sectional view of a structure used in Example 2.

FIG. 19 is a diagram showing a synthetic carbon dioxide laser beam.

FIG. 20 is a diagram showing superposition of a synthetic Ar laser beam and a synthetic carbon dioxide gas laser beam.

FIG. 21 is a plan view of a structure used in Example 6.

22 is a sectional view of a structure used in Example 6. FIG.

FIG. 23 is a cross-sectional view of a structure used in Example 8.

FIG. 24 is a plan view of a structure used in Example 9.

FIG. 25 is a cross-sectional view of a structure used in Example 9.

FIG. 26 is a diagram showing a configuration example of a thin film manufacturing apparatus.

[Explanation of symbols]

700 structure 701 substrate 702 semiconductor layer 703 surface protective layer 1604 SiON layer 2104, 2304 SiN layer 2507 first laser (carbon dioxide gas laser) 2508 second laser (Ar laser) 3001 chamber 3002 energy beam generation source 3003 energy beam optics System and focusing system 3005 Energy beam scanning optical system 3006 Control mechanism 3007 Blower mechanism 3008 Structure moving mechanism

─────────────────────────────────────────────────── --Continued from the front page (56) Reference JP-A 61-44786 (JP, A) JP-A 60-164318 (JP, A) JP-A 61-106484 (JP, A) JP-A 62- 274710 (JP, A) JP 63-209118 (JP, A) JP 5-234885 (JP, A) JP 5-263220 (JP, A) JP 5-335234 (JP, A) Special table Sho-60-501501 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C30B 1/00-35/00 H01L 21/20 H01L 21/208

Claims (8)

(57) [Claims] 1. A structure in which a polycrystalline or amorphous semiconductor layer is formed on a substrate and a surface protective layer is formed on the semiconductor layer is subjected to a zone melting recrystallization method to obtain the structure. In the thin film forming method of melting the semiconductor layer by heating in a strip shape, moving the strip heating area in a direction orthogonal to the longitudinal direction of the strip heating area, and recrystallizing the semiconductor layer, the zone melting recrystallization Melt at the beginning of the chemical process
State thermal gradient to the solid state in the steep by facet growth crystal from, performs control so as to face the specific crystal axes of the crystal in the direction of movement of the heating zone, Netsu勾after this
The growth mode of crystal growth is made cell-like by making the composition gentle.
A method for forming a thin film, which comprises shifting to growth . 2. The thin film forming method according to claim 1 ,
As the structure, a structure is used in which the film thickness of the surface protective layer in the portion where the melt recrystallization is first performed is made larger than the film thickness of the surface protective layer on the downstream side of the melt recrystallization. Method for forming thin film. 3. The thin film forming method according to claim 1 ,
A method for forming a thin film, characterized in that, as the structure, a structure in which a cooling layer is further provided on a surface protective layer in a portion where melt recrystallization is first performed is used. 4. The thin film forming method according to claim 1 ,
A method for forming a thin film, characterized in that the moving speed of the band-shaped heating region is set to be high in the initial stage of melt recrystallization and then to be low. 5. The thin film forming method according to claim 1 ,
A thin film forming method characterized in that a band-shaped energy beam is used as a heating source, and the energy beam convergence width is made small at the initial stage of the melt recrystallization and then made large. 6. The thin film forming method according to claim 1 ,
A first laser in which the laser beam is absorbed by the substrate or the surface protective layer and a second laser in which the laser beam is absorbed by the semiconductor layer are used as a heating source, and the output of the second laser is melted. A method for forming a thin film, which comprises increasing the size in the initial stage of recrystallization and then decreasing the size. 7. The thin film forming method according to claim 1 ,
A method for forming a thin film, characterized in that, as the structure, a structure in which the surface protective layer has a thick band-shaped region and a thin band-shaped region along a longitudinal direction of a heating region is used. 8. The thin film forming method according to claim 1 ,
When laser light is used as a heating source, the structure is a structure having a laser light antireflection film on the surface protective layer at predetermined intervals along the longitudinal direction of the heating region. A method for forming a thin film.