JP2017157694A - Method and device of manufacturing crystalline film and amorphous thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deposition method capable of doping impurities of a low concentration with accuracy to a group III-V compound semiconductor, such as GaN, by the PLD method.SOLUTION: A group-III target containing impurities and that is in a liquid-phase state is irradiated with laser light having a picosecond-order pulse width at a repetition frequency equal to or more than a threshold of a repetition frequency related to a deposition speed, and thereby, the target is evaporated by ablation. An activated group-V material is simultaneously supplied to form a compound semiconductor on a substrate. An impurity concentration of a film to be formed on the substrate is adjusted by a temperature of the target.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method of crystal growth mainly in a compound semiconductor such as a nitride semiconductor, a method of forming an insulating film containing oxygen and nitrogen, and an apparatus for manufacturing them.

  Wide band gap semiconductors typified by nitride semiconductors (III-V semiconductors) are being put to practical use in LEDs and optical devices. These semiconductors are formed by a crystal growth method such as MOCVD (Metal Organic Chemical Deposition) or MBE (Molecular Beam Epitaxy).

  MOCVD is generally used to form nitride semiconductors, but it uses expensive organic metals as raw materials and requires simultaneous supply of hydrogen to decompose into Ga, nitrogen, etc. There is a problem that it is high and there are many defects.

  MBE requires an ultra-high vacuum to obtain good-quality crystals, and in order to vaporize the source material by heating, particularly when a film having a high melting point such as an insulating film is formed, the temperature must be extremely high. A cooling mechanism for the device is required. The composition control of the film to be formed is determined by the source material, and the composition cannot be controlled by the film formation conditions as in MOCVD.

As another crystal growth method, a crystal growth method by PLD (Pulsed Laser Deposition) has been proposed. PLD focuses a pulsed laser beam with a pulse width on the order of nanoseconds on the target, rapidly heats the irradiated area of the target material to above the melting point, and the material emitted from the surface of the target It is a method of forming and flying on a substrate to form a film.
Compared with MBE, there is a feature that a cooling mechanism is not required, the apparatus configuration is simple, a film having a high melting point can be formed, the film forming speed can be easily controlled, and film forming can be performed with a wide range of pressures.
When a composite target (alloy target) is used in the PLD method, the plume has the same composition ratio as the composition of the target. Therefore, in order to change the composition of the film to be formed, targets having different composition ratios must be prepared.

Patent Document 1 discloses a method of dividing a target and controlling a mixed crystal ratio in order to control the film composition in the PLD method. If laser irradiation is performed while rotating the divided target, a desired composition ratio can be obtained according to the division ratio and the ablation rate of the material.
Further, Patent Document 2 discloses a method of controlling the composition of a film to be formed by irradiating a target mixed with two kinds of powder materials with a femtosecond pulse laser and ablating the target material.

Japanese Patent Laid-Open No. 5-208895 JP 2007-288141 A

  However, the conventional PLD method has a problem that the introduction of impurities and the mixed crystal ratio are easily affected by the uniformity of the composition ratio of the target, and the controllability and reproducibility are low. In particular, a technique for adding impurities at a low concentration (for example, 1% or less) for conductivity control is still in the research stage and has not been established. For example, in the target dividing method of Patent Document 1, it is not possible to control the content of minute impurities as used in the manufacturing process of a semiconductor element.

  Moreover, since the PLD having a pulse width of nanosecond level is a heating process, the target is thermally evaporated. For this reason, there may be a problem that micrometer-sized particles are emitted from the target and the crystallinity of the deposited film is deteriorated. As a countermeasure against this, as in Patent Document 2, in order to deposit a material by ablation which is a non-heating process, a PLD having a pulse width of femtosecond order has been developed. However, a laser with a pulse width on the order of femtoseconds has poor stability, and the film deposition rate is low, resulting in high manufacturing costs. In addition, the wavelength distribution of the laser beam is broad, and it is difficult to focus using existing optical lenses. There is a problem that. Patent Document 2 discloses a target in which two kinds of powder materials are mixed as a method for doping impurities in a film formed by the PLD method. Such a target has an influence on the particle size distribution of the powder. It is difficult to obtain uniformity and reproducibility of the composition of the formed film.

  In view of the above problems, the present invention provides a novel film formation method by the PLD method that improves the controllability of the composition of the compound and has stable film formation characteristics.

The method for producing a crystal film according to the present invention includes:
The group III material is irradiated with pulsed laser light having a repetition frequency equal to or higher than the threshold of the repetition rate related to the deposition rate and a pulse width of 1 picosecond or more and 1000 picoseconds or less, and the group III material is vaporized and the group V material is formed on the substrate. Is supplied to the substrate to grow a group III and group V compound on the substrate.

  By adopting such a crystal film manufacturing method by the PLD method, it becomes possible to focus laser light on the surface of a target made of a group III material with an existing optical lens, and maintain continuous excitation by a laser pulse. A group III material is deposited on a substrate by ablation of a non-thermal process at a repetition frequency threshold or higher, specifically 50 to 70 [kHz] or higher, and an activated group V material, such as nitrogen radicals, is formed on the substrate. By supplying to the surface and reacting with the group III material, a high-quality group III and group V compound such as a nitride semiconductor can be crystal-grown at a stable deposition rate.

In the method for producing a crystal film according to the present invention,
The Group III material contains impurities for controlling conductivity, and the Group III material is held at a constant temperature and liquefied to control the concentration of the impurities in the Group III material. May be.

  In order to control the composition ratio of the mixture of the group III material constituting the target and the impurity concentration of other elements, the target is held at a constant temperature of about the melting point by using the phase diagram of the two elements. In the mixed state of the liquid phase and the solid phase, the composition ratio of the liquid phase group III material and impurities, that is, the impurity concentration to be doped is controlled. In this way, a crystal film having a desired composition ratio (impurity concentration) can be deposited on the substrate by ablation by irradiating the surface of the liquid target (liquid phase target) whose impurity concentration is controlled with a pulse laser beam. By determining the holding temperature based on the phase diagram, it is possible to obtain a liquid phase target having a concentration different from the impurity concentration contained in the group III as a target raw material. As a result, the impurity concentration of the group III film deposited on the substrate can be set or adjusted to a desired value. For example, the impurity concentration of the nitride semiconductor can be accurately controlled.

Furthermore, since the target surface irradiated with laser light is liquid, even if the irradiated portion of the laser light evaporates and is lost, the material flows from the surrounding liquid phase target, the target surface becomes flat, and the impurity concentration also increases. Since it can be maintained at a constant value, film formation by the PLD method can be performed in a stable state.
Therefore, unlike the solid target, it is not necessary to move the irradiation region on the solid target for the purpose of preventing fluctuation in film formation promotion due to the depression due to the laser beam irradiation.

The method for producing a crystal film according to the present invention includes:
The group III material is gallium containing germanium of 0.6 [atm%] or less.

  When GaN is deposited, liquid Ga (gallium) at about 30 ° C. can be used as a target. Therefore, when an impurity is to be doped, a liquid target can be formed at a relatively low temperature. In particular, when doping Ge (germanium) as an n-type impurity, there is a region where the melting point is lower than Ga alone until the Ge concentration is 0.6 [atm%] ([mol%]). Becomes important. That is, there is a eutectic point at a Ge concentration of 0.55 [atm%], and the Ge concentration approaches a constant value as the target temperature approaches the eutectic point temperature from the melting point. Regardless of whether the concentration of Ge in Ga serving as a target raw material is higher or lower than 0.55 [atm%], it can be brought close to the concentration of Ge at the eutectic point by temperature control, and the n-type with high accuracy. The impurity concentration of the GaN semiconductor can be controlled.

The method for producing an amorphous film according to the present invention includes:
The oxide material or nitride material is irradiated with a pulse laser beam having a repetition frequency equal to or higher than the threshold of the repetition rate related to the deposition rate and a pulse width of 1 picosecond or more and 1000 picoseconds or less, and the oxide material is mixed in a nitrogen and oxygen mixed atmosphere. Alternatively, an oxynitride amorphous film is formed on the substrate by vaporizing the nitride material and supplying an activated group V material on the substrate.

Thus, it can be used not only for the formation of a crystalline film but also for the formation of an amorphous film.
In the case where the surface of the substrate is provided with a group III and group V compound semiconductor, for example, a nitride semiconductor such as GaN, an activated group V material, for example, nitrogen radicals are supplied to the surface of GaN. Nitrogen (group V material) is prevented from being detached from the surface, and part of the nitrogen is taken into the formed insulating film to form an oxynitride film, so that a dense insulating film can be formed.

The method for producing a laminated film according to the present invention includes:
After the formation of the oxynitride amorphous film,
Irradiating the target made of an electrically conductive metal oxide with the laser pulse light in an oxygen atmosphere,
Or, in an oxygen atmosphere, irradiate the laser pulse light to a target made of a metal whose oxide is electrically conductive while supplying activated oxygen on the substrate,
An electrically conductive metal oxide film is formed on the non-crystalline film of oxynitride.

  Thus, by continuously forming the film in a vacuum state without opening to the atmosphere, impurities such as moisture do not enter the interface between the insulating film and the electrode (electrically conductive oxide film). Therefore, a stable field effect transistor can be manufactured by applying this laminated film as a gate insulating film.

A film forming apparatus according to the present invention includes:
A chamber having an exhaust port, a gas introduction port, and a light transmission window;
A target container for accommodating a target inside the chamber;
A substrate support for supporting a substrate provided facing the target;
A discharge device for supplying a group V material toward the substrate support;
A laser beam having a pulse width of 1 picosecond or more and 1000 picoseconds or less is generated outside the chamber at a repetition frequency equal to or higher than a threshold of a repetition frequency related to a deposition rate, and the laser light is transmitted through the light transmission window, A laser light generator for irradiating the target surface with laser light;
It is characterized by providing.

In addition, a film forming apparatus according to the present invention includes:
A temperature control device is provided that keeps the temperature of the target contained in the target container constant.

Furthermore, the film forming apparatus according to the present invention includes:
The light transmission window is configured as one end of a substantially cylindrical sleeve extending to the target container along the optical path of the laser light,
The sleeve is configured to have a cross-sectional area smaller than the light transmission window inside the chamber.

In addition, a film forming apparatus according to the present invention includes:
An exhaust port for connecting to a vacuum pump is provided in a part of the sleeve.

  By adopting the above device configuration, the target surface is irradiated with a picosecond order pulse laser and deposited on the substrate, and the group V material activated by the emission device is emitted and supplied toward the substrate support. By reacting with the film deposited on the substrate placed on the substrate support base, a compound is formed, or the activated group V material is released until immediately before the deposition, and V is released from the film provided on the substrate. A substance vaporized from the target can be stably formed on the substrate at a high deposition rate while preventing the separation of the group material. By introducing gas from the gas inlet during film formation (evaporation), it is possible to control the atmosphere during film formation. In addition, by maintaining the target at a constant temperature and mixing the liquid phase and the solid phase, it is possible to change and control the composition of the liquid phase target, and as a result, the impurity concentration of the film formed on the substrate can be controlled. Even if the concentration is low, it can be controlled with high accuracy. Furthermore, the opening portion of the cylindrical sleeve transmits laser light, but the opening portion becomes smaller when viewed from the light transmission window, thereby evaporating from the target and reducing the amount of material flying to the light transmission window, Further, by exhausting the inside of the cylindrical portion, it is possible to suppress the adhesion of the film of the light transmission window, reduce the change with time of the laser light intensity, and perform the film formation by the stable PLD method at low cost.

  By the film forming method of the present invention, the impurity concentration of a film to be formed, for example, a nitride semiconductor can be controlled by temperature, and a re-grown epitaxial film with high reproducibility and low cost can be formed. In addition, by applying the film formed according to the present invention to the source / drain regions, the series resistance of the GaN power transistor is greatly reduced, so that the loss of the transistor can be reduced.

The block diagram of the PLD apparatus which concerns on this invention. The figure which shows the repetition frequency dependence of the deposition rate of the Ge dope Ga film concerning this invention. The state diagram explaining the principle of the composition control of the liquid target which concerns on this invention. The phase diagram of Ga-Mg system. The phase diagram of Ga-Ge system. The block diagram of the PLD apparatus of other embodiment which concerns on this invention.

(First embodiment)
The configuration of the PLD apparatus according to the present invention will be described below with reference to FIG.

(Device configuration)
The PLD apparatus includes a substrate support 2 and a target temperature control device 3 inside a chamber 1 that is a vacuum container having airtightness. A substrate 4 that is a target for forming a film is placed on the substrate support 2, and the substrate support 2 heats the substrate 4 to a maximum temperature of 1000 ° C. with a built-in heating device. It can be kept at a constant temperature. Although not shown, a substrate rotating / moving mechanism for rotating / moving the substrate may be provided for uniform film quality.

  On the target temperature control device 3, a target container 5a is arranged. In the target container 5a, for example, a source material to be deposited such as a mixture of elements such as Ga and Mg or Ge, that is, a target 6a is stored. The target temperature control device 3 can heat the target 6a via the target container 5a, or cool it as necessary, and keep it at a constant temperature. For example, when the target temperature rises to a set value or higher due to radiant heat from the heated substrate 4, heating and cooling may be combined to improve temperature controllability.

  A plurality of target containers can be provided. In FIG. 1, different targets 6a and 6b are stored in two target containers 5a and 5b, respectively. The target container 5a or the target container 5b is selected according to the material to be deposited and moved onto the target temperature control device 3, and the targets 6a and 6b are held at a constant temperature. Note that the number of target containers is not limited to two, but may be more or one.

  The chamber 1 includes a light transmission window 7 for introducing laser light. A pulse laser 9 emitted from a laser light generator 8 installed outside the chamber 1 is collected by a lens 10, introduced into the chamber 1 through a light transmission window 7, and irradiated onto a target 6a. .

  The material evaporates from the surface of the target 6 a irradiated with the laser light and is emitted toward the opposing substrate 4, and the emitted material forms a plume 11.

  The chamber 1 further includes a gas inlet 12, an exhaust outlet 13, and a radical gun 14. An atmosphere control gas, such as nitrogen or oxygen, is flow-controlled by an MFC (mass flow controller) as required, and can be introduced into the chamber 1 through the gas inlet 12.

  A vacuum pump is connected to the exhaust port 13 so that the inside of the chamber 1 can be exhausted and kept in a vacuum state. In addition, when the atmosphere control gas is introduced from the gas inlet 12, the opening degree of an APC (Auto Pressure Controller) valve installed between the exhaust port 13 and the vacuum pump and the rotation speed of the vacuum pump are controlled. It is possible to keep the pressure inside the chamber 1 constant.

For example, a gas such as nitrogen (N ₂ ) is introduced into the radical gun 14, and activated gas and radical are generated from the gas and supplied toward the substrate 4. For example, when nitrogen gas is introduced, N ₂ radicals or N radicals are released.

(Laser light)
In the PLD according to the present invention, a laser beam having a pulse width of picosecond order, in this embodiment, 1 picosecond to 1000 picosecond is used. The repetition frequency of the laser pulse can be several tens [kHz] or more, which is several orders of magnitude higher than that of the conventional femtosecond pulse laser (1 to several tens [Hz]). The repetition frequency can be set within the range of the response speed of the saturable absorber of the laser light generator 8. For example, the repetition frequency can be set to about 300 [kHz]. The center wavelength of the laser is 1064 [nm], and the energy of one pulse is 50 [μJ].

  By setting the pulse width and repetition frequency as described above, sufficient fluence (laser light energy density per pulse) can be obtained, and at shorter intervals than the plume relaxation time, laser ablation by non-heating process The target can be evaporated.

  In addition, unlike the conventional femtosecond pulse laser, the frequency distribution of the pulse laser is sharp, so that it can be focused on the target using an existing optical lens. The laser diameter on the target can be reduced to 100 [μm] or less, for example, 50 [μm]. As a result, ablation can be efficiently performed.

FIG. 2 shows the repetition frequency dependence of the deposition rate. The center wavelength of the laser is 1064 [nm], the pulse width is 24 [ps] (picoseconds), and an example of a fluence of 1.1 [J / cm ² ] is shown. The target was Ge-doped Ga.

From FIG. 2, our analysis shows that the deposition rate increases from 70 [kHz], and that there is a threshold frequency in the repetition rate dependence of the deposition rate in the PLD of picosecond pulses. It became clear. The threshold of the repetition frequency at the start of ablation depends on the fluence, and ranges from 50 [kHz] (in the case of fluence 2.3 [J / cm ² ]) to 70 [kHz] (in fluence 1.1 [J / cm ² ]). It is also clear that the repetition frequency threshold decreases with increasing laser pulse energy.

  A stable crystal can be formed by setting a repetition frequency equal to or higher than the threshold of the repetition frequency related to the deposition rate so that the evaporated material becomes a substantially continuous flow at a repetition frequency equal to or higher than the threshold.

(Liquid target)
FIG. 3 is a state diagram for explaining the effect of the liquid target of the present invention. For understanding the principle, FIG. 3 shows a model of a phase diagram of a binary alloy of Ga and another element X as a binary alloy.

  A dotted line α in FIG. 3 indicates a mixing ratio of raw materials. A point A on the dotted line α is only the liquid phase, a solid phase begins to precipitate in the liquid phase at the point B, and a liquid phase and a solid phase coexist at the point C. The composition of the liquid phase is the same as the composition of the intersection D of the isotherm of point C and the liquidus. Therefore, a liquid phase having a composition different from the mixing ratio of the raw materials can be obtained by adjusting the temperature of the raw materials. A liquid target surface of a mixture of two elements is irradiated with laser light, and a film having a liquid phase composition corresponding to the temperature can be formed on the substrate from the material released from the liquid target by ablation. .

That is, by controlling the temperature of the liquid target in the temperature range of the liquidus and solidus at the mixing ratio of the raw materials, the substrate can be realized within the range that can be realized by the liquidus in the phase diagram without replacing the target. The composition of the film to be formed can be freely changed.
Although FIG. 3 shows an example of the total solid solution, the composition ratio of the liquid phase can be similarly controlled by temperature control in other cases.

  FIG. 4 shows a phase diagram of an alloy of Ga and Mg. Although the composition range of the liquid phase that can be controlled differs depending on the mixing ratio of the raw materials, the liquid phase of the mixing ratio obtained from the liquidus line can be maintained by maintaining the target at a temperature at which the liquid phase and the solid phase are mixed. It can be understood that it can be realized. Mg is an element used as a p-type impurity of a GaN semiconductor. For use in, for example, the source and drain regions of a GaN transistor, the Mg concentration in the raw material Ga is, for example, several [atm%] or less (10 [ atm%] or less), and the temperature may be controlled near the melting point of Ga.

  FIG. 5 shows a phase diagram of an alloy of Ga and Ge. In the center of FIG. 5, a phase diagram up to a Ge mixing ratio of 1 [atm%] is shown enlarged. It can be understood that it has a eutectic point at a Ge concentration of 0.55 [atm%].

  The intersection of the 29.8 ° C. isotherm of the melting point of Ga and the liquidus corresponds to a Ge mixing ratio of 0.6 [atm%]. When the mixing ratio of Ge in Ga of the target raw material is in the range of 0.6 [atm%] or less and 0.55 [atm%] or more, the target temperature is lower than the melting point of Ga and the eutectic point temperature is reached. As it approaches, the Ge concentration in the liquid phase decreases and approaches 0.55 [atm%]. When the Ge mixing ratio in the raw material Ga is 0.55 [atm%] or less, the temperature of the target is lower than the melting point of Ga, and the Ge concentration in the liquid phase increases as the temperature approaches the eutectic point temperature. It approaches [atm%].

  That is, when the mixing ratio of Ge in the raw material Ga is 0.6 [atm%] or less, that is, before and after the mixing ratio of the eutectic point, the target temperature is controlled within the range of the melting point and the eutectic point temperature of Ga. The closer the temperature of the eutectic point is, the closer the Ge concentration in the liquid phase of Ga and Ge approaches the Ge concentration of eutectic point of 0.55 [atm%]. Therefore, the impurity concentration in the liquid phase can be controlled by controlling the target temperature regardless of the amount of variation in the ratio of Ge mixed with Ga.

Ge is, for example, an n-type impurity of a GaN semiconductor, and its concentration of 0.55 [atm%] corresponds to 10 ¹⁹ [/ cm ³ ] in terms of number density. This concentration is used for the source, drain, etc. of semiconductor transistors and is the most frequently used impurity concentration. By using raw materials having a Ge concentration of 0.6 [atm%] or less in Ga, Precise concentration control is possible.

(Radical irradiation)
As shown in FIG. 1, the chamber 1 can be supplied with nitrogen, which is an activated group V element, on the substrate surface. The material evaporated from the target 6a by the pulse laser beam adheres to the substrate 4 which is a film formation target, and at the same time, activated nitrogen, that is, nitrogen radicals, is supplied from the radical gun 14, and reacts on the surface to form nitride. It is formed. When the target 6a is Ga containing n-type or p-type impurities, Ga and nitrogen react on the surface of the substrate 4 to form a GaN film that is a nitride semiconductor. In this case, nitridation may be promoted by introducing nitrogen gas from the gas inlet 12.

  A film to be formed is not limited to a semiconductor material, and an insulating film such as a silicon oxide film, a nitride film, an aluminum oxide film, a hafnium oxide film (HfOx), a zirconium oxide (ZrOx), or the like is used. It is also possible to form on the substrate 4. The target 6b can be formed on the substrate 4 by laser ablation using the oxide film, the nitride film, or the like. At this time, by introducing oxygen gas, nitrogen gas, or a mixed gas thereof from the gas inlet 12, oxidation or nitridation can be promoted to form an insulating film having a stable film quality.

  Further, when an insulating film is formed on the surface of the GaN semiconductor, nitrogen is easily released from the surface of the GaN film. Therefore, detachment of nitrogen can be prevented by irradiating the surface of the GaN film with nitrogen radicals from the radical gun 14 until immediately before growing the insulating film.

  In addition, since nitrogen is partially taken into the formed insulating film and becomes an oxynitride film, there is an effect that a dense insulating film is formed. That is, it is possible to form an oxynitride film that has a tendency to reduce leakage current and improve reliability with respect to the oxide film.

Such an oxynitride film can be specifically formed by the following two methods.
Method 1: A film is formed while irradiating nitrogen radicals on a MOx (eg, aluminum oxide) target.
Method 2: A film is formed in an oxygen atmosphere (while irradiating nitrogen radicals) on a target of MN (eg, aluminum nitride).
In the above, M means a metal.

  Furthermore, since a plurality of targets can be mounted in the PLD apparatus according to the present invention, different types of films can be continuously formed in a vacuum (without opening to the atmosphere).

After forming the insulating film, the target at the laser light irradiation position is exchanged in the PLD apparatus, and an electrically conductive oxide such as NiOx (nickel oxide), SnOx (tin oxide), CoOx (cobalt oxide), etc. By using a metal oxide as a target and irradiating laser light in an oxidizing atmosphere, an electrically conductive oxide film can be stacked on the insulating film.
In this case, oxygen gas may be introduced into the radical gun 14 to release oxygen activated during film formation, that is, oxygen radicals, toward the substrate 4.
Note that a laminated film can be continuously formed in a vacuum without changing the laser irradiation conditions.

  Further, as a method for forming an electrically conductive oxide film, a metal having an electrically conductive oxide, such as Ni, Sn, or Co, is used as a target, irradiated with laser light in an oxidizing atmosphere, and further activated from the radical gun 14. By releasing oxygenated oxygen, that is, oxygen radicals, toward the substrate 4, the metal and oxygen may be reacted, and the electrically conductive metal oxide film may be continuously stacked in a vacuum. Note that when a metal is used as the target, it is essential to release oxygen radicals.

Such continuous film formation prevents impurities such as moisture from entering the interface between the insulating film and the electrode (conductive oxide film). Therefore, when the insulating film is applied as a gate insulating film of a field effect transistor having a MIS structure, a stable field effect transistor can be manufactured.
In addition, since the oxides of Ni, Sn, and Co are P-type wide bandgap semiconductors, an equivalent work function can be increased, and for example, there is an advantage on the device that a field effect transistor can be normally off.

(Second Embodiment)
Below, the PLD apparatus in 2nd Embodiment is demonstrated.

  In the film formation by the PLD method, laser light is introduced into the chamber 1 from the outside through the light transmission window 7, and the material is evaporated from the surface of the target 6 a (or 6 b) by ablation to form a film on the substrate 4.

  The material emitted from the target 6 a is deposited not only on the substrate 4 but also on the light transmission window 7. In particular, when nitrogen or oxygen gas is introduced under atmosphere control, atoms fly over a wide range due to multiple scattering, and adhesion to the light transmission window 7 increases.

  When a film is formed on the light transmission window 7, the transmittance of the laser light is lowered, and the material emitted from the surface of the target 6a is gradually reduced. For this reason, in order to maintain the deposition rate and form a stable quality film, the light transmission window 7 must be appropriately cleaned or replaced, which reduces the apparatus operating rate.

  In the present embodiment, as shown in FIG. 6, a cylindrical sleeve 15 is provided along the optical path of the laser beam to solve the above problem.

  That is, according to this configuration, the light transmission window 7 is configured as one end of a substantially cylindrical sleeve 15 extending to the target container 5a along the optical path of the laser beam. As shown in FIG. 6, the sleeve 15 is configured to have a cross-sectional area smaller than that of the light transmission window 7 inside the chamber 1. Since the laser light is condensed by the lens 10 and is narrowed down to a narrow region of, for example, about 100 [μm] φ on the surface of the target container 5a, the opening area of the end surface on the target container 5a side is light having a diameter of about several centimeters. It is sufficiently smaller than the transmission window 7 and can be set to several mm or less, for example, 1 [mm].

  Thus, by reducing the opening area of the end surface on the target container 5a side, the amount of the target released from the surface of the target 6a and entering the sleeve 15 can be reduced.

  Further, the sleeve 15 may have an exhaust port 16 for being connected to a vacuum pump (not shown), and the inside thereof may be always exhausted to maintain a vacuum state.

  According to such a configuration, even when the gas by the atmosphere control is introduced from the gas inlet 12, the inside of the sleeve 15 can be evacuated independently, and therefore the presence of the sleeve 15 affects the pressure control inside the chamber 1. Therefore, film formation can be performed stably.

DESCRIPTION OF SYMBOLS 1 Chamber 2 Substrate support 3 Target temperature control device 4 Substrate 5a, 5b Target container 6a, 6b Target 7 Light transmission window 8 Laser light generator 9 Pulse laser 10 Lens 11 Plume 12 Gas introduction port 13 Exhaust port 14 Radical gun 15 Sleeve 16 Exhaust port

Claims (9)

    The group III material is irradiated with a pulsed laser beam having a repetition frequency equal to or higher than the threshold of the repetition rate related to the deposition rate and a pulse width of 1 picosecond or more and 1000 picoseconds or less to vaporize the group III material, and a group V material on the substrate A crystal film manufacturing method characterized in that a group III and a group V compound are grown on the substrate by supplying a crystal on the substrate.   The Group III material contains an impurity for controlling conductivity, and the Group III material is maintained at a constant temperature to be in a mixed state of a liquid phase and a solid phase. 2. The method for producing a crystal film according to claim 1, wherein the concentration is controlled.   3. The method of manufacturing a crystal film according to claim 1, wherein the group III material is gallium containing germanium of 0.6 [atm%] or less.   The oxide material or nitride material is irradiated with a pulse laser beam having a repetition frequency equal to or higher than a threshold of the repetition rate related to the deposition rate and a pulse width of 1 picosecond or more and 1000 picoseconds or less, and the oxide is mixed in a nitrogen and oxygen mixed atmosphere Alternatively, an amorphous film of oxynitride is formed on the substrate by vaporizing the nitride material and supplying an activated group V material on the substrate. After forming the non-crystalline film of the oxynitride according to claim 4,
Irradiating the target made of an electrically conductive metal oxide with the laser pulse light in an oxygen atmosphere,
Or, in an oxygen atmosphere, irradiate the laser pulse light to a target made of a metal whose oxide is electrically conductive while supplying activated oxygen on the substrate,
A method for producing a laminated film, comprising: forming an electrically conductive metal oxide film on the amorphous film of oxynitride A chamber having an exhaust port, a gas introduction port, and a light transmission window;
A target container for accommodating a target inside the chamber;
A substrate support for supporting a substrate provided facing the target;
A discharge device for supplying a group V material toward the substrate support;
A laser beam having a pulse width of 1 picosecond or more and 1000 picoseconds or less is generated outside the chamber at a repetition frequency equal to or higher than a threshold of a repetition frequency related to a deposition rate, and the laser light is transmitted through the light transmission window, A laser light generator for irradiating the target surface with laser light;
A film forming apparatus comprising:   The film forming apparatus according to claim 6, further comprising a temperature control device that maintains a constant temperature of the target accommodated in the target container. The light transmission window is configured as one end of a substantially cylindrical sleeve extending to the target container along the optical path of the laser light,
The film forming apparatus according to claim 6, wherein the sleeve is configured to be smaller than a cross-sectional area inside the chamber than the light transmission window. The film forming apparatus according to claim 8, wherein an exhaust port for connection to a vacuum pump is provided in a part of the sleeve.

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