JPH05171425A - Device and method for forming thin compound film - Google Patents

Abstract

PURPOSE:To enhance the controllability of the conversion and to efficiently form a high quality thin compd. film. CONSTITUTION:A reactive gas is thermally dissociated by heating a nozzle 41 for jetting the reactive gas with the radiant heat of a nozzle heating filament 43. The nozzle 41 is biased positively to a gas ionizing filament 26 and directly irradiated with thermoelectrons so as to ionize the reactive gas near the outlet of the nozzle 41 at which the concn. of the gas is high and to enhance the reactivity of the gas as well as to further heat the nozzle 41.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms a compound thin film such as an amorphous silicon thin film on a substrate by irradiating a substrate provided in a vacuum chamber with a cluster ion beam and a reactive gas. And a method for forming a compound thin film.

[0002]

2. Description of the Related Art Conventionally, compound thin films such as titanium nitride (TiN), alumina (Al ₂ O ₃ ) and silicon carbide (SiC) have been coated on the surface of parts by a method such as a sputtering method or a CVD method. However, the compound thin film formed by such a method is insufficient in composition,
In addition, there are problems such as weak adhesion.

In 1975, Spear (WE Sp
The silicon hydride compound (commonly known as amorphous silicon) obtained by the thermal decomposition of silane (SiH ₄ ) by glow discharge and the like has a disordered diamond structure, and hydrogen bonds to the resulting dangling bonds. It is solid and widely used as a pn junction semiconductor material for solar cells and the like. The performance of this solar cell is determined by bonding as much hydrogen as possible to the dangling bonds of silicon, but the above conventional method has a limit in increasing the hydrogen composition.

FIG. 3 shows, for example, "Proceedings of the Seventh Symposium on Ion Source and Ion Assisted Technology" (Pr.
oceedings of the seventh Symposium on Ion Source a
It is a block diagram which shows the conventional reactive cluster ion beam (R-ICB) apparatus shown by nd Ion Assisted Technology.

In the figure, 1 is a vacuum tank, 2 is a vacuum exhaust system for maintaining the inside of the vacuum tank 1 at a predetermined degree of vacuum, and 3 is a steam generation source provided in the vacuum tank 1. Is
It comprises a closed crucible 4 having a nozzle 4a, a heating filament 5 for heating the crucible 4 and a heat shield plate 6. Reference numeral 7 is a vapor deposition material filled in the crucible 4, and 8 is a cluster (lumped atomic group) formed by ejecting vapor of the vapor deposition material 7 from the crucible 4.

Reference numeral 9 denotes an ionizing means provided around the passage of the cluster 8. The ionizing means 9 includes an ionizing filament 10, an extracting electrode 11 for extracting and accelerating electrons from the ionizing filament 10 and a heat shield plate.
It consists of 12. 13 is an acceleration electrode for accelerating the ionized cluster 8 with an electric field to give kinetic energy, 14
Is a substrate having a compound thin film formed on its surface, and 15 is a power supply accommodating first to third DC power supplies 16 to 18 for bias and first and second AC power supplies 19 and 20 for heating filaments. It is a device.

Reference numeral 21 denotes a reactive gas introducing system for introducing a reactive gas into the vacuum chamber 1. The reactive gas introducing system 21
Is composed of a gas cylinder 22 filled with a reactive gas such as oxygen, nitrogen or hydrogen, an introduction pipe 23 and a flow rate adjusting valve 24.

Next, the function of each bias power supply in the power supply device 15 will be described. First, the first DC power source 16 positively biases the potential of the crucible 4 with respect to the heating filament 5 so that the thermoelectrons emitted from the heating filament 5 collide with the crucible 4. Next, the second DC power supply 17 positively biases the potential of the extraction electrode 11 with respect to the ionization filament 10 so as to extract the thermoelectrons emitted from the ionization filament 10 into the extraction electrode 11. In addition, the third DC power source 18 is the acceleration electrode 13 which is at the ground potential.
On the other hand, the potentials of the extraction electrode 11 and the crucible 4 are positively biased, and the positively charged cluster ions are accelerated and controlled by the electric field lens formed therebetween.

Next, the operation will be described. After the vacuum chamber 1 is evacuated by the vacuum exhaust system 2 to a vacuum degree of 10 ^-4 Torr or less, the flow rate adjusting valve 24 is opened and the reactive gas is introduced from the gas cylinder 22 into the vacuum chamber 1 through the introduction pipe 23. ..

On the other hand, when the crucible 4 is heated by the thermoelectrons emitted from the heating filament 5 to a temperature at which the vapor pressure in the crucible 4 becomes several Torr, the vapor deposition substance 7 evaporates, and the nozzle 4a is placed in the vacuum chamber 1 Is injected into. When the injected vapor passes through the nozzle 4a, it is accelerated and cooled by adiabatic expansion and condensed to form the cluster 8.

The clusters 8 are partially ionized by thermoelectrons emitted from the ionizing filament 10. The ionized cluster 8 is accelerated by the electric field formed by the acceleration electrode 13 and collides with the substrate 14 together with the non-ionized neutral cluster 8. At this time, since the reactive gas exists near the substrate 14, the reaction between the cluster 8 and the reactive gas proceeds on the substrate 14,
A compound thin film is deposited on the substrate 14.

However, the conventional R-ICB as described above is used.
In the apparatus, since the reactive gas in the vacuum chamber 1 is in a low activity molecular state, the reaction efficiency is low, and most of the reactive gas is exhausted without being used for thin film formation. For this reason,
Attempts have been made to enhance reaction efficiency by exciting, dissociating, and partially ionizing and activating a reactive gas.

FIG. 4 is a block diagram showing another example of the conventional R-ICB device disclosed in, for example, Japanese Patent Laid-Open No. 63-11662, in which a gas ion source is provided side by side with the ICB source. In the figure, 25 is a gas injection nozzle provided at the tip of the introduction tube 23, 26 is a gas ionization filament which is an electron beam emission means provided around the passage of the reactive gas, and 27 is a gas ionization filament 26. And an extraction electrode provided between the gas injection nozzle 25 and the gas injection nozzle 25.

Reference numeral 28 is a substrate for the gas ionization filament 26.
A gas ion accelerating electrode provided on the 14 side for accelerating gas ions, 29 is an internal tank accommodating them, and 30 is a gas cylinder 2
2, introduction pipe 23, flow control valve 24, gas injection nozzle 25,
The gas ionization filament 26, the extraction electrode 27, the gas ion acceleration electrode 28, and the inner tank 29 are gas ion sources.

Reference numeral 31 is a third AC power source for heating the gas ionization filament 26, 32 is a fourth DC power source for biasing the extraction electrode 27 positively with respect to the gas ionization filament 26, and 33 is a gas for the extraction electrode 27. A fifth DC power source for positively biasing the ion accelerating electrode 28 is a gas ion source power source 34 including a third AC power source 31, a fourth DC power source 32, and a fifth DC power source 33. Other parts are the same as in FIG. The power supply device 15 (FIG. 3) is not shown.

Next, the operation will be described. A gas cylinder 22 is placed in the vacuum chamber 1 which is kept at a high vacuum by the vacuum exhaust system 2.
The reactive gas from is introduced. And the flow control valve
With 23, the gas pressure in the vacuum chamber 1 is adjusted to be about 10 ⁻⁴ to 10 ⁻³ Torr. At this time, the gas pressure in the inner tank 29 is kept higher.

On the other hand, the reactive gas is excited, dissociated or partially ionized by the thermoelectrons emitted from the gas ionization filament 26 toward the extraction electrode 27, and becomes in an activated state. Further, as in the case of FIG. 3, the ionized cluster 8 is made to collide with the substrate 14 together with the non-ionized cluster (or vapor) 8.

As a result, the activated reactive gas and the clusters 8 of the vapor deposition material 7 collide with each other and the reaction proceeds to deposit a compound thin film on the substrate 14. In addition, the kinetic energy of the reactive gas incident on the substrate 14 and the kinetic energy of the cluster 8 can be independently controlled by adjusting the accelerating voltage applied by the accelerating electrode 13 and the gas ion accelerating electrode 28 independently of each other. It is possible to control the physical properties and crystallinity (single crystal, polycrystal, amorphous, etc.) of the thin film.

[0019]

In the conventional R-ICB apparatus as shown in FIG. 4, although the reactivity is somewhat higher than that shown in FIG. 3, the controllability of the reaction rate is high. There was a problem that was insufficient. In particular,
When silicon is used as the vapor deposition material 7 and silane gas is used as the reactive gas to form a thin film of amorphous silicon, the dissociation of the silane gas is insufficient and a solar cell for power generation of a practical level with high energy conversion efficiency. In order to manufacture hydrogen, it is desired to realize an apparatus capable of freely controlling the rate at which hydrogen bonds to the dangling bonds of silicon.

The present invention has been made to solve the above problems, and it is possible to sufficiently increase the reactivity of the reactive gas, thereby improving the controllability of the reaction rate. An object of the present invention is to obtain a compound thin film forming apparatus and a compound thin film forming method which can be performed.

[0021]

In a compound thin film forming apparatus according to a first aspect of the invention, a gas ion source is provided with a gas injection nozzle for injecting a reactive gas, and nozzle heating means for heating the gas injection nozzle. It is a thing.

In the compound thin film forming apparatus according to the second aspect of the present invention, the gas injection nozzle for injecting the reactive gas, the electron beam emission means for emitting thermionic electrons, and the gas injection nozzle with respect to the electron beam emission means are disposed directly. The gas ion source is provided with a nozzle bias power source for biasing the gas ion source.

In the method for forming a compound thin film according to the third aspect of the invention, the gas injection nozzle is heated when the reactive gas is injected.

In the method for forming a compound thin film according to the invention of claim 4, when the reactive gas is injected, the electron beam emitting means for emitting thermoelectrons for ionization of the reactive gas,
The gas injection nozzle is positively biased so that thermoelectrons are directly irradiated to the gas injection nozzle.

[0025]

In the inventions of claims 1 and 3, it is possible to increase the reactivity of the reactive gas by heating the gas injection nozzle and thermally dissociating the reactive gas in the gas injection nozzle. To do.

In the inventions of claims 2 and 4,
Directly irradiating the gas injection nozzle with thermoelectrons to thermally dissociate the reactive gas in the gas injection nozzle and ionize the reactive gas near the outlet of the gas injection nozzle, which has a high concentration of the reactive gas. It makes it possible to increase the reactivity.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. Example 1. FIG. 1 is a block diagram showing an R-ICB device according to an embodiment of the invention of claims 1 to 4, and the same or corresponding parts to those in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted.

In the figure, 41 is a metal gas injection nozzle connected to the introduction pipe 23 and provided in the vacuum chamber 1, and 42 is a ceramic gas injection nozzle 41 for insulating the gas injection nozzle 41 from the vacuum chamber 1. An insulating material, 43 is provided around the gas injection nozzle 41, and is a nozzle heating filament as nozzle heating means for heating the gas injection nozzle 41 with radiant heat. 44 is a gas injection nozzle 41, a nozzle heating filament 43, and gas ionization. An internal tank for shielding the filament 26, 45 is a gas ionization filament 26, a gas ion acceleration electrode 28, a gas injection nozzle 41, a nozzle heating filament 43 and an internal tank.
44 is a gas ion source.

Reference numeral 46 is a fourth AC power source for heating the nozzle heating filament 43, and 47 is a gas ionization filament 26.
With respect to the sixth DC power supply as a nozzle bias power supply for positively biasing the gas injection nozzle 41, 48 is a seventh DC power supply for positively biasing the gas injection nozzle 41 with respect to the nozzle heating filament 43, 49 Is an eighth direct current power source for positively biasing the gas injection nozzle 41 with respect to the gas ion accelerating electrode 28, and 50 is a third and fourth alternating current power sources 31, 46 and sixth to eighth direct current power sources 47, 48, It is a power supply device for a gas ion source consisting of 49 and.

Further, an ion cluster beam source, that is, I
The CB source 51 is similar to that shown in FIG.
It has an ionization means 9 and an acceleration electrode 13. Note that I
Illustration of the power supply device 15 (FIG. 3) of the CB source 51 is omitted.

Next, the operation will be described. First, as in the conventional example, the reactive gas is introduced into the vacuum chamber 1 that has been evacuated so that the gas pressure in the vacuum chamber 1 is about 10 ⁻⁵ to 10 ⁻³ Torr. At this time, in the apparatus of this embodiment, the gas injection nozzle 41 is heated by the radiant heat from the nozzle heating filament 43. Further, since the gas injection nozzle 41 is positively biased with respect to the gas ionization filament 26, the thermoelectrons emitted from the gas ionization filament 26 are radiated to the gas injection nozzle 41, which causes the gas injection nozzle 41 to move. It is heated to a higher temperature.

When the gas injection nozzle 41 is heated to a high temperature, the reactive gas is partially thermally dissociated and injected. Further, the reactive gas injected from the gas injection nozzle 41 is further excited, dissociated or partially ionized by the thermoelectrons irradiated from the gas ionization filament 26 toward the gas injection nozzle 41, and is highly activated. It will be in a state of being.

Next, similarly to the conventional example, the cluster 8 of the vapor deposition material 7 is jetted from the vapor generation source 3. These clusters 8 are partially ionized by the ionization means 9, accelerated by the acceleration electrode 13, and collide with the substrate 14.
At this time, since the reactive gas exists in the vicinity of the substrate 14, the reaction between the cluster 8 and the reactive gas proceeds on the substrate 14 to deposit the compound thin film on the substrate 14.

In such an R-ICB apparatus, the gas injection nozzle 41 is heated to a high temperature to thermally dissociate the reactive gas, and the reactive gas is discharged near the outlet of the gas injection nozzle 41 having a high gas concentration. Since it is ionized, the reactivity of the reactive gas can be efficiently increased, and as a result, the controllability of the reaction rate becomes high.

In particular, a silane (SiH ₄ ) or disilane (Si ₂ H ₆ ) gas, or a mixed gas of silane or disilane and hydrogen (H ₂ ) is excited, dissociated or partially ionized by the gas ion source 45. In the amorphous silicon thin film formed by depositing silicon (Si) by the ICB source 51, silane or disilane gas is dissociated with high efficiency. For this reason, the degree of freedom in controlling the rate at which hydrogen bonds to the dangling bonds of silicon is increased, and as a result, it is possible to inexpensively manufacture a practical-level solar cell for power generation with improved energy conversion efficiency.

Example 2. FIG. 2 shows claims 1 to 4.
6 is a configuration diagram showing an R-ICB device according to another embodiment of the invention of FIG. In the figure, 52 is a magnetic field applying means provided on the outer periphery of the inner tank 44, and 53 is a porous electrode provided on the upper part of the inner tank 44.

In such an R-ICB device, the internal tank 44
Since the porous electrode 53 is provided on the inner surface of the inner tank 44, the gas pressure in the inner tank 44 can be kept higher. In addition, the filament 26 for gas ionization
When irradiating the electron beam toward the gas injection nozzle 41 from the magnetic field application unit 52, the magnetic field applying unit 52 causes the electron beam to make a spiral motion. Thereby, the activation of the reactive gas can be further enhanced.

The vapor deposition material 7 and the reactive gas are not limited to those in the above embodiments. In each of the above embodiments, the nozzle heating filament is used as the nozzle heating means.
Although 43 is shown, another gas may be used as long as it can heat the gas injection nozzle 41.

[0039]

As described above, according to the inventions of claims 1 and 3, by heating the gas injection nozzle and thermally dissociating the reactive gas in the gas injection nozzle,
Since the reactivity of the reactive gas can be increased, the controllability of the reaction rate can be increased, and the effect of efficiently forming a high-quality compound thin film can be obtained.

According to the second and fourth aspects of the present invention, the gas injection nozzle is directly irradiated with thermoelectrons to thermally dissociate the reactive gas in the gas injection nozzle, and the reactive gas is concentrated in the gas injection nozzle. Since it is possible to increase the reactivity of the reactive gas by ionizing near the exit of the high-injection gas injection nozzle, it is possible to increase the controllability of the reaction rate and efficiently form a high-quality compound thin film. The effect is obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an R-ICB device according to an embodiment of the inventions of claims 1 to 4. FIG.

FIG. 2 is a configuration diagram showing an R-ICB device according to another embodiment of the present invention.

FIG. 3 is a configuration diagram showing an example of a conventional R-ICB device.

FIG. 4 is a configuration diagram showing another example of a conventional R-ICB device.

[Explanation of symbols]

1 Vacuum Tank 14 Substrate 26 Gas Ionization Filament (Electron Beam Emitting Means) 41 Gas Injection Nozzle 43 Nozzle Heating Filament (Nozzle Heating Means) 45 Gas Ion Source 47 Sixth DC Power Supply (Nozzle Bias Power Supply) 51 ICB Source

Claims (4)

[Claims] 1. A compound provided on a substrate provided in a vacuum chamber is irradiated with a cluster ion beam from a cluster ion beam source and is irradiated with gas ions of a reactive gas from a gas ion source. In the compound thin film forming apparatus for forming a thin film, the gas ion source includes a gas injection nozzle that is provided in the vacuum chamber and injects the reactive gas, and a nozzle heating unit that heats the gas injection nozzle. A compound thin film forming apparatus characterized by the above. 2. A substrate provided in a vacuum chamber is irradiated with a cluster ion beam from a cluster ion beam source and is irradiated with gas ions of a reactive gas from a gas ion source to form a compound on the substrate. In a compound thin film forming apparatus for forming a thin film, the gas ion source is provided in the vacuum chamber to inject the reactive gas, and a gas injection nozzle is provided on the substrate side of the gas injection nozzle to emit thermoelectrons. And a nozzle bias power source for directly irradiating the gas injection nozzle with the thermoelectrons by positively biasing the gas injection nozzle with respect to the electron beam emission means. Compound thin film forming apparatus. 3. A method for forming a compound thin film, comprising irradiating a substrate provided in a vacuum chamber with a cluster ion beam and gas ions of a reactive gas to form a compound thin film on the substrate, wherein the reaction A method for forming a compound thin film, which comprises heating a gas injection nozzle when injecting a reactive gas. 4. A method for forming a compound thin film, comprising irradiating a substrate provided in a vacuum chamber with a cluster ion beam and gas ions of a reactive gas to form a compound thin film on the substrate. When injecting volatile gas,
With respect to the electron beam emitting means for emitting thermoelectrons for ionizing the reactive gas, the gas injection nozzle is positively biased, and the thermoelectrons are directly irradiated to the gas injection nozzle. Forming method.