JP3552749B2 - Film forming apparatus and film forming evaporation source apparatus - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a film forming apparatus and a film forming evaporation source apparatus, and more particularly to an apparatus for growing a film of these compound crystals on a substrate using a chemically stable raw material and an unstable raw material. .
[0002]
[Prior art]
A vacuum deposition method is known as a physical film formation method under vacuum (PVD method). Vacuum evaporation is a technique for forming a thin film by heating and evaporating or sublimating a material in a vacuum and transporting the vapor onto another substrate having a relatively low temperature to condense and precipitate the material. The vacuum promotes evaporation of the source material. In addition, the efficiency of the vapor transport process is increased to promote the formation of a film, and the raw material is degraded or deteriorated by a reaction such as thermal decomposition or oxidation by contact with air (oxygen) in a high-temperature evaporator. It works effectively to prevent
[0003]
The basic steps in the PVD process are: first, the release of the source material into the gas phase space, second, the transport of the vapor in the space, and third, the injection and deposition of the vapor on the substrate surface. Consists of steps. Here, in the process of discharging into the gas phase space, a so-called “crucible” is used as a means for supplying a lump, powder or particles of the raw material, and a Knudsen-type crucible, a divergent nozzle-type crucible, or the like has conventionally been used as a crucible for evaporation. Are known.
[0004]
At the time of film formation, the raw material is put into a crucible in the atmosphere, and the raw material is evaporated by heating the bottom in a vacuum. Then, the vapor is released into the gas phase space (vacuum space) through the opening at the top, and is transported in the direction of the substrate. When the film formation is completed, the vacuum state is leaked, and the film-formed substrate is taken out in the air. At this time, the raw materials in the crucible are exposed to the atmosphere.
[0005]
[Problems to be solved by the invention]
Many of the deposition materials are chemically stable, but some are chemically unstable. When such an unstable substance is exposed to the atmosphere after the film forming process, it reacts with components in the atmosphere, for example, oxygen and water vapor, and a reaction product appears on the surface of the raw material mass.
[0006]
Incidentally, when growing a PbSrS crystal film composed of lead, strontium and sulfur, a lump of PbS (lead sulfide) and Sr (strontium) is used as a raw material, but Sr is chemically unstable, so Strontium hydroxide is easily generated on the surface. For this reason, for example, when the substrate is replaced in the air after the first film formation and the next film formation process is performed, the evaporation of Sr from the Sr lump having the reaction product with the air component adhered to the surface thereof, As compared with the first time, it is not suitably performed, and good film formation cannot be performed.
[0007]
The present invention has been completed in order to overcome such disadvantages of the prior art, and has a film forming apparatus capable of stably and satisfactorily growing a crystal film using a chemically unstable substance as a part or all of a raw material. It is another object of the present invention to provide a film-forming evaporation source device used for this.
[0008]
[Means for Solving the Problems]
The film forming apparatus according to the present invention evaporates a first raw material (for example, PbS) and a second raw material (for example, Sr) having a higher reactivity with an atmospheric component than the first raw material in a vacuum, In an apparatus for growing a crystal film (for example, PbSrS) containing first and second raw materials on a substrate, first evaporation source means for heating (for example, 560 ° C.) and evaporating the first raw material; A second evaporation source means for heating and evaporating the raw material, wherein the second evaporation source means comprises: a raw material mass arrangement member on which a second mass of raw material is arranged; A raw material mass heating means for heating the mass of the second raw material having a reaction product (for example, strontium hydroxide) with a component in the atmosphere to a temperature (for example, 700 ° C.) sufficient to evaporate the mass of the second raw material; A raw material film on which a film of the second raw material evaporated from the lump is deposited on the surface And having a product member, and a raw material film heating means for evaporating the second material film raw material film deposition member is heated (e.g., 470 ° C.).
[0009]
Here, when the second raw material (for example, Sr) has high reactivity with the constituent element (for example, S) of the first raw material, the raw material lump heating means uses the reaction product ( For example, the raw material mass placing member is heated to a temperature sufficient to evaporate the second raw material mass having SrS) on the surface.
[0010]
The evaporation source apparatus for film formation according to the present invention is an apparatus for heating and evaporating a raw material for growing a crystal film on a substrate by evaporating the raw material into a vacuum. The bottom of the container is heated to a temperature sufficient to evaporate the lump of raw material having a reaction product with components in the air on the surface and deposit a film of the raw material on the inner surface of the container. And a raw material film heating means for heating the side wall of the container and evaporating the raw material film.
[0011]
In addition, the film forming evaporation source device according to the present invention is a device for heating first and second raw materials for growing a crystal film on a substrate, respectively, and evaporating the same in a vacuum. A partition is provided substantially at an intermediate portion, and an opening which is narrowed upward and protrudes is formed at a substantially central portion of the partition, and a lump of the second raw material is disposed at a bottom thereof, and a first raw material is disposed on the partition. And the bottom of the container is heated to a temperature sufficient to evaporate a mass of the second material having a reaction product of atmospheric components on the surface thereof and deposit a film of the second material on the inner surface of the container. Raw material mass heating means for heating, a raw material heating means for heating the side wall below the partition wall of the container to evaporate the second raw material film, and a heating means for heating the side wall above the partition wall of the container to evaporate the first raw material And characterized in that:
[0012]
Here, when the second raw material (for example, Sr) has high reactivity with the constituent element (for example, S) of the first raw material, the raw material lump heating means uses the reaction product ( The bottom of the container is heated to a temperature sufficient to evaporate the mass of the second material having SrS) on its surface and deposit a film of the second material on the inner surface of the container.
[0013]
[Action]
According to the film forming apparatus of the present invention, the chemically stable first raw material is evaporated by the first evaporation source means, and the unstable second raw material is evaporated by the second evaporation source means. Includes a means for heating a raw material mass, a member on which a raw material film is deposited by vapor from the raw material mass, and a means for heating the raw material film. The heating of the raw material mass is performed at a temperature sufficient to evaporate the raw material mass having a reaction product with an atmospheric component or another raw material constituent element on the surface. Even if a reaction product appears on the surface due to thermal instability, a raw material film containing almost no reaction product can be generated. Therefore, the second raw material can be suitably evaporated using the raw material film as an evaporation source, so that a stable and good crystal film can be grown.
[0014]
In the evaporation source apparatus for film formation of the present invention, since the container in which the raw material lump is placed at the bottom has an opening which is squeezed at the top and protrudes, only the temperature at which the raw material lump evaporates (the reaction product By heating to a temperature sufficient to evaporate a raw material lump having a substance), a raw material film containing almost no reaction product with atmospheric components can be formed on the inner surface other than the bottom of the container. Since the raw material film is heated via the wall surface of the container, the raw material for film formation can be supplied to the gas phase space using the raw material film as an evaporation source of the raw material.
[0015]
According to another evaporation source apparatus for film formation of the present invention, the container is divided into two chambers, upper and lower, by a partition having an opening protruding upward, and a chemically unstable first chamber is formed in a lower section. An evaporation source for the second raw material and a stable evaporation source for the first raw material are set in the upper section. In the lower section, the raw material mass at the bottom is heated to grow a raw material film on the inner surface, and the raw material film is evaporated to supply vapor upward from the opening. Therefore, the stable first raw material and the unstable second raw material can be respectively discharged into the gas phase space from the upper two openings (double structure openings).
[0016]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the same reference numerals are given to the same elements, and the duplicate description will be omitted.
[0017]
FIG. 1 shows a main part of a film forming apparatus according to an embodiment, in which a left half is a side view and a right half is a cross-sectional view. The container (crucible) for accommodating the raw material is composed of an upper half 11 and a lower half 12, both of which are cylindrical in cross section, and the inner diameter of the upper half 11 is slightly larger than the outer shape of the lower half 12. They are fitted and joined to form a single unit. The upper half 11 has a partition 13 near the lower end, and a substantially central portion thereof forms a cylindrical body 14 which is narrowed upward and protrudes. The lower half 12 is open only at the upper side, the open end thereof abuts against the partition 13 of the upper half 11, and the bottom is molded in a substantially hemispherical shape.
[0018]
Outside the container, first, second and third heaters 21, 22, 23 are provided from the bottom, and thermocouples 31, 32 for measuring the temperature of each part corresponding to each heater 21, 22, 23 are provided. , 33 are provided. Here, the first heater 21 mainly heats the bottom of the lower half 12 of the container, the second heater 22 heats the side wall of the lower half 12, and the third heater 23 heats the upper half 11 Is heated near the upper part of the partition 13.
[0019]
An openable and closable shutter 4 is provided above the opening of the upper half 11 of the container, a substrate holder 5 is mounted above the shutter 4, and a substrate 6 on which a film is to be formed is placed here. A fourth heater 24 for heating the substrate 6 is provided above the substrate holder 5, and a thermocouple 34 is provided corresponding to the fourth heater 24.
[0020]
A procedure for forming a film on the substrate 6 using the apparatus shown in FIG. 1 will be described.
[0021]
First, two types of raw material masses for a crystal film are put in a container in the atmosphere. The raw material masses disposed at the bottom of the lower half 12 are chemically unstable, and are placed on the partition 13 of the upper half 11. The raw material mass to be arranged is chemically stable. Then, the chamber (not shown) of the vacuum device is closed, and the vacuum pump (not shown) is driven to supply electricity to the _first heater 21 under vacuum through the terminal TM1. At this time, the shutter 4 is closed, and the temperature at the bottom of the lower half 12 is higher than the evaporation temperature of the raw material mass, that is, a reaction product with oxygen, hydrogen and the like in the atmosphere is present on the surface of the raw material mass. Even so, the temperature is set to a high temperature at which the raw material is sufficiently evaporated.
[0022]
Next, the heating by the first heater 21 is stopped, and the heating by the second heater 22 and the third heater 23 are simultaneously started. That is, to start the energization from the terminal TM ₂ and the terminal TM ₃ At the same time, the temperature of the side wall of the lower half 12 of the case (temperature measured by thermocouple 32) is not above reaction product to the surface The temperature is set to a temperature at which evaporation can be performed from a chemically unstable raw material mass. The lower temperature of the upper half 11 (the temperature measured by the thermocouple 33) is a temperature at which the chemically stable raw material mass can be evaporated.
[0023]
When the evaporation of the raw material starts, the shutter 4 is opened. Thereby, the evaporating substance is transported toward the substrate 6 in the vacuum, and a crystal film composed of a compound of a chemically stable raw material and an unstable raw material is formed on the back surface of the substrate 6. In this state, it is assumed that the substrate 6 is heated by the fourth heater 24 to a temperature suitable for film formation.
[0024]
When the film formation for a certain period of time is completed, the shutter 4 is closed, the power supply to the first to fourth heaters 21 to 24 is all stopped, and cooling is performed under vacuum. After cooling to near room temperature, a valve (not shown) is opened to bring the inside of the chamber to atmospheric pressure, and the chamber is opened. Next, the film-formed substrate 6 is taken out, a new substrate 6 is set on the substrate holder 5, and the chamber is closed. Then, the vacuum pump is operated to return to a vacuum state again, and the above-described process is repeated.
[0025]
In the present embodiment, as described above, a two-stage heating process is employed for evaporating a chemically unstable raw material. For this reason, suitable evaporation can be performed for unstable raw materials as well as for stable raw materials.
[0026]
The features and effects of this embodiment will be described with reference to FIG. Here, it is assumed that the film is formed of PbSrS, the chemically stable raw material is PbS, and the unstable raw material is Sr.
[0027]
First, as shown in FIG. 2A, a PbS mass is set in the upper half 11 of the container, and an Sr mass is set in the lower half 12 of the container. Then, heating the Sr mass to temperatures _{T 1} as a vacuum state. Here, chemically unstable Sr mass has a strontium hydroxide on the surface, ordinary not good in the evaporation temperature T ₂ evaporation Sr. Therefore, Sr is evaporated by setting the temperature T ₁ (about 700 ° C.) higher than the normal temperature (about 470 ° C.).
[0028]
Then, as shown in FIG. 2B, Sr vapor from the Sr lump collides with the inner surface of the lower half 12, and an Sr film is formed. It is needless to say that the Sr film is chemically unstable, but does not react with atmospheric components because the inside is maintained in a vacuum.
[0029]
Therefore, as shown in FIG. 2 (c), and at the same time the side wall of the lower half 12 to the normal evaporation temperature T ₂ of the Sr, the lower portion of the upper half 11 and the evaporation temperature of the PbS (about 560 ° C.) . Thus, evaporation from both the raw materials Sr and PbS starts, and a PbSrS film is grown on the substrate 6.
[0030]
When the film formation on the substrate 6 is completed, the whole is cooled, the vacuum is broken, and the atmosphere is introduced. Thereby, the surface of the Sr lump at the bottom of the lower half 12 of the container and the residual Sr film on the inner surface of the lower half 12 are transformed into strontium hydroxide. However, in the next film formation process after replacing the substrate 6 after film formation with a new substrate 6, the Sr lump is again brought to a temperature T ₁ (700 ° C.) higher than the normal temperature T ₂ (470 ° C.). There is no failure in the evaporation of Sr from the Sr mass. Furthermore, the lower half 12 the inner surface of the container, new since Sr film is formed on the strontium hydroxide remaining, there is no problem in evaporation at ordinary temperature T _2.
[0031]
According to this embodiment, the unstable Sr is evaporated from a fixed area of the inner surface of the lower half 12 of the container, so that the evaporation can be controlled at a constant speed by controlling the temperature. For this reason, extremely high-precision film thickness control can be performed as compared with the case of evaporating from a Sr lump having a strotium hydroxide film or particles attached to the surface.
[0032]
The film forming apparatus and the evaporation source apparatus according to the present invention are not limited to the above-described embodiment, and various modifications are possible.
[0033]
First, chemically unstable materials include not only materials having high reactivity with atmospheric components but also materials having high reactivity with constituent elements of other raw materials used at the same time. Incidentally, in the growth of the PbSrS crystal, when temperature rise, growth, slow cooling, and the like are performed in the apparatus containing the raw materials, the growth is performed while the residual gas in the growth chamber is evacuated, but a part remains in the growth chamber. Then, depending on the temperature conditions, SrS may be formed on the surface of the Sr lump, which causes the same harm as strontium hydroxide. Therefore, the above problem can be overcome by forming a raw material film from a raw material lump in the first stage and then evaporating the raw material film in the second stage, as in the above embodiment.
[0034]
In the embodiment of FIGS. 1 and 2, the container (crucible) is constituted by upper and lower halves and has a so-called two-stage structure with respect to the evaporation source device. It is sufficient that the generated raw material film can be heated and separated separately, and need not be integrated with a stable raw material mass evaporation mechanism. That is, as shown in FIG. 3, prepared pot-shaped crucible 10A, the bottom temperature T _1, may be attached to the heater (not shown) capable of heating the side wall to a temperature T _2.
[0035]
In this case, for example, a test tube type crucible 10B is separately prepared, and a chemically stable raw material lump is put therein. Then, the film forming apparatus of the present invention is configured by being housed in the chamber 7 together with the shutter 4 and the substrate holder 5. Thus, for example, using conventional Knudsen type crucible, the bottom temperature T _1, in the case of providing a heater for heating the side to temperature T ₂ also consists film formation evaporation source device of the present invention.
[0036]
The crystal film formed in the present invention is, for example, a mixed crystal compound semiconductor film containing an alkaline earth metal or a rare earth metal. For example, PbSe (lead selenide), ZnS (zinc sulfide), ZnSe (zinc selenide) Is a film containing an unstable substance such as Sr (strontium) and Eu (europium) in a stable material such as Sr. Then, for example, PbSrS can be used as a cladding layer of a semiconductor laser having PbS as an active layer, and a long-wavelength semiconductor laser having a wavelength of 3 μm can be obtained.
[0037]
【The invention's effect】
As described above in detail, according to the present invention, a chemically unstable raw material mass can be heated to a temperature higher than a normal evaporation temperature, and a raw material film as an intermediate can be formed in a vacuum. Only by heating the raw material film in the above, the raw material can be stably and suitably evaporated. Therefore, there is an effect that a compound crystal film containing a chemically unstable raw material can be grown under highly accurate composition control and film thickness control. Japanese Patent Application Laid-Open No. 217264/1990 discloses an evaporation source that heats in two stages. This is to evaporate the unused raw material on the crucible wall so that the component ratio of the raw material does not fluctuate. However, the effect of the present invention cannot be obtained at all.
[Brief description of the drawings]
FIG. 1 is a diagram showing a film forming evaporation source apparatus according to an embodiment of the present invention and a film forming apparatus using the same.
FIG. 2 is a view showing a process of growing a compound film according to the embodiment of FIG. 1;
FIG. 3 is a diagram showing a film forming evaporation source device according to a modification and a film forming apparatus using the same.
[Explanation of symbols]
11: Upper half of container (crucible), 12: Lower half of container (crucible), 13: Upper and lower partition walls, 21: First heater for heating chemically unstable raw material mass, 22: Chemical A second heater for heating a chemically unstable raw material film, a third heater for heating a chemically stable raw material, a fourth heater for heating a substrate, a shutter, a substrate holder , 6 ... substrate.
Yoshiki Hasegawa, Patent Attorney

Claims (5)

A first raw material and a second raw material having a higher reactivity with components in the atmosphere than the first raw material are evaporated in a vacuum to grow a crystal film containing the first and second raw materials on a substrate. In the film forming apparatus,
First evaporation source means for heating and evaporating the first raw material;
Second evaporation source means for heating and evaporating the second raw material,
The second evaporation source means,
A raw material lump arrangement member on which the second raw material lump is disposed;
Raw material mass heating means for heating the raw material mass arrangement member to a temperature sufficient to evaporate the mass of the second raw material having a reaction product with a component in the air on the surface;
A raw material film deposition member on which a film of the second raw material evaporated from the mass of the second raw material is deposited;
A film heating device for heating the material film deposition member to evaporate the film of the second material. In a film forming evaporation source apparatus for heating a raw material for growing a crystal film on a substrate and evaporating the raw material in a vacuum,
A container having an opening that is squeezed and protruded at the top, and a container in which the mass of the raw material is arranged at the bottom,
Raw material mass heating means for heating the bottom of the container to a temperature sufficient to evaporate the mass of the raw material having a reaction product with components in the atmosphere on the surface and deposit a film of the raw material on the inner surface of the container When,
A source film heating means for heating a side wall of the container to evaporate the source material film. In a film forming evaporation source apparatus for heating a first and a second raw material for growing a crystal film on a substrate and evaporating them in a vacuum,
An opening is formed at the top and a partition is provided at a substantially middle portion. An opening is formed at a substantially central portion of the partition so as to be squeezed upward and protrudes. The mass of the second raw material is provided at the bottom at the first portion. The raw material of the container disposed on the partition,
Heating the bottom of the container to a temperature sufficient to evaporate a mass of the second raw material having a reaction product with atmospheric components on the surface and deposit a film of the second raw material on the inner surface of the container Raw material mass heating means to be
Material film heating means for heating the side wall below the partition wall of the container to evaporate the film of the second material;
Heating means for heating a side wall of the upper part of the partition wall of the container to evaporate the first raw material. The first raw material and the second raw material having high reactivity with the constituent elements of the first raw material are evaporated in a vacuum to grow a crystal film containing the first and second raw materials on a substrate. In the film forming equipment,
First evaporation source means for heating and evaporating the first raw material;
Second evaporation source means for heating and evaporating the second raw material,
The second evaporation source means,
A raw material lump arrangement member on which the second raw material lump is disposed;
A raw material mass heating means for heating the raw material mass disposing member to a temperature sufficient to evaporate the mass of the second raw material having a reaction product with a constituent element of the first raw material on the surface;
A raw material film deposition member on which a film of the second raw material evaporated from the mass of the second raw material is deposited;
A film heating device for heating the material film deposition member to evaporate the film of the second material. In a film forming evaporation source apparatus for heating a first and a second raw material for growing a crystal film on a substrate and evaporating them in a vacuum,
It has an opening at the top and a partition almost in the middle, and an opening that is narrowed upward and protrudes almost at the center of the partition, and has high reactivity with the constituent elements of the first raw material. A mass of the second raw material at the bottom thereof, the first raw material being a container disposed on the partition,
The container is heated to a temperature sufficient to evaporate a lump of the second raw material having a reaction product with a constituent element of the first raw material on the surface and deposit a film of the second raw material on the inner surface of the container. Raw material mass heating means for heating the bottom of
Material film heating means for heating the side wall below the partition wall of the container to evaporate the film of the second material;
Heating means for heating a side wall of the upper part of the partition wall of the container to evaporate the first raw material.

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