JP2889039B2 - Thin film forming equipment - 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 forming apparatus for forming a thin film using a chemical reaction of a reactive gas.

[0002]

Using a chemical reaction in the Related Art mainly hot space or activated space to form a thin film, the thin film forming apparatus according to the rock <br/> loose C VD method is known. The present applicant has proposed a high-performance thin film forming apparatus by a CVD method using both electron beam irradiation and ion beam acceleration means (Japanese Patent Application Laid-Open No. 62-238364).

FIG. 2 is a diagram schematically showing a cross section of a conventional thin film forming apparatus disclosed in, for example, JP-A-62-238364. In the figure, 1 is a vacuum tank, 2 is an exhaust system for keeping the vacuum tank 1 at a high vacuum, 3 is an exhaust valve, 4 is a thin film forming substrate disposed on the upper side in the vacuum tank 1, and 5 is a vacuum. An internal tank, which is disposed on the lower side in the tank 1 and has a cutout 5a formed in the wall facing the substrate 4, is disposed on the lower side in the internal tank 5 and faces the substrate 4 side. A nozzle for injecting reactive gas,
7 is a cylinder for supplying a reactive gas, 8 is a flow control valve,
Reference numeral 9 denotes a passage for the reactive gas which is formed from the injection hole of the nozzle 6 toward the notch 5a of the internal tank 5.

[0004] Further, reference numeral 10 denotes an electron beam extraction electrode made of a tungsten wire disposed in the reactive gas passage 9, and 11 is disposed above the electron beam extraction electrode 10 so as to surround the reactive gas passage 9. An electron beam emitting means 12 composed of a filament to be formed, 12 is an accelerating electrode having a notch 12a at the center so as to form a passage 9 for the reactive gas, and 13 is a ground provided around the notch 5a of the internal tank 5. Electrodes, 14 are an AC power supply for heating the electron beam emission means 11, 15 is a first DC power supply for keeping the electron beam extraction electrode 10 at a positive potential with respect to the electron beam emission means 11, 1
Reference numeral 6 denotes a second DC power supply for maintaining the acceleration electrode 12 at a positive potential with respect to the ground electrode 13 and applying an acceleration voltage to reactive gas ions from the acceleration electrode 12 toward the ground electrode 13;
Is an excited ionization region of a reactive gas formed from the internal bath 5 to the substrate 4. Here, the substrate 4 is configured to have the same potential as the ground electrode 13.

Next, the operation of the conventional thin film forming apparatus will be described. As an example, a case in which a hydrocarbon-based C _x H _{2 y} gas is used as a reactive gas to cause a reaction of CxH ₂ y → XC + YH ₂ to form a graphite film or a diamond film will be described.

[0006] First, a cylinder 7 and a nozzle 6 are placed in an internal tank 5 in a vacuum tank 1 maintained at a high vacuum by an exhaust system 2.
The reactive gas is introduced via. At this time, the flow rate of the reactive gas is adjusted by the flow rate adjustment valve 8 provided in the line from the cylinder 7 so that the gas pressure in the vacuum chamber 1 becomes about 10 ^-4 to 10 ^-3 Torr.

Next, the first direct current is emitted from the electron beam emitting means 11 heated to about 2000 ° C. by the AC power supply 14 to the electron beam extraction electrode 10 arranged on the upper surface of the nozzle 6 so that the electron beam is emitted. A voltage of about 10 to 100 V is applied by the power supply 15 to emit an electron beam of about 1 to 5 A. In this case, the electron beam extraction electrode 10 is heated by the electron beam.

[0008] The hydrocarbon-based gas, which is a reactive gas, is dissociated by a reaction of C _x H _{2 y} → C + YH ₂ by the heated electron beam extraction electrode 10 and the above-mentioned electron beam. Some of the free carbon and hydrogen formed are bombarded with the electron beam to be excited and partially ionized.

On the other hand, the second DC power supply 16 applies 0 to several KV to the acceleration means comprising the acceleration electrode 12 and the ground electrode 13.
When an acceleration voltage of about the same level is applied, the ions of the above-described reactive gas are accelerated and reach the substrate 4 to form a carbon film on the substrate 4 together with the dissociated and excited gas. in this case,
By changing the acceleration voltage, it is possible to control the kinetic energy of carbon ions or hydrogen ions incident on the substrate 4, thereby changing the quality of the carbon film formed on the substrate 4 from graphite to amorphous carbon, It can be controlled to a carbon film and even a diamond film.

[0010]

The conventional thin film forming apparatus is configured as described above, and the kinetic energy of the ions of the reactive gas is changed by the accelerating voltage applied between the accelerating electrode 12 and the ground electrode 13. When the acceleration voltage is changed, the amount of ions of the reactive gas drawn from the internal bath 5 to the substrate 4 side changes when the acceleration voltage is changed. There is a problem that the amount of ions of the reactive gas reaching the substrate 4 becomes extremely small, and a high-quality thin film cannot be sufficiently formed on the substrate 4.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and it is possible to irradiate a substrate with a certain amount of reactive gas ions even if the acceleration voltage is changed, and to achieve a desired value corresponding to the acceleration voltage. It is an object of the present invention to provide a thin film forming apparatus capable of forming a high quality thin film.

[0012]

According to the thin film forming apparatus of the present invention, the acceleration means is provided in a ground electrode provided around the notch in the internal tank and in a reactive gas passage. An accelerating electrode to which a positive accelerating voltage is applied, and a drawer disposed in a reactive gas passage between the accelerating electrode and the ground electrode, wherein a negative withdrawal voltage is applied to the ground electrode. And an electrode.

[0013]

According to the thin film forming apparatus of the present invention, a drawing voltage is applied to the negative side with respect to the ground electrode between the ground electrode and the acceleration electrode to which the acceleration voltage is applied to the positive side with respect to the ground electrode. Since the extraction electrode is provided, the reactive gas ions can be extracted from the inner tank to the substrate side (accurately to the extraction electrode) with the sum voltage of the acceleration voltage and the extraction voltage, and the acceleration voltage is reduced. Even in this case, the substrate can always be irradiated with a certain level of reactive gas ions.

Further, since the extraction voltage is applied to the extraction electrode on the negative side with respect to the ground electrode, the ions of the reactive gas are decelerated by the extraction voltage until they reach the ground electrode from the extraction electrode. The substrate is irradiated with the kinetic energy given by the acceleration voltage.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a view schematically showing a cross section of a thin film forming apparatus according to an embodiment of the present invention. In the drawing, the same or corresponding parts as those of the conventional thin film forming apparatus shown in FIG. The description is omitted.

In the drawing, reference numeral 17 denotes an extraction electrode provided between the accelerating electrode 12 and the ground electrode 13 and provided with a cutout 17a at the center thereof so as to form a reactive gas passage 9. Is used to connect the extraction electrode 17 to the ground electrode 13
On the other hand, a third DC power supply that supplies a voltage for extracting ions of the reactive gas to the extraction electrode 17 while maintaining the potential on the negative side opposite to that of the acceleration electrode 12. In addition, the extraction electrode 17 constitutes a means for accelerating reactive gas ions together with the acceleration electrode 12 and the ground electrode 13 described above.

Next, the operation of the above embodiment will be described for the case where a hydrocarbon C _X H _{2 Y} gas is used as the reactive gas. As in the above-described conventional thin film forming apparatus, the reactive gas introduced into the internal bath 5 is dissociated by the action of an electron beam or the like, and a part of the released carbon and hydrogen is excited,
It is also partially ionized. The ions (carbon ions or hydrogen ions) of the reactive gas are accelerated by an accelerating voltage applied between the accelerating electrode 12 and the ground electrode 13 by the second DC power supply 16, and are dissociated and excited together with the gas. And a thin film is formed on the substrate 4.

On the other hand, in this case, an extraction voltage is applied to the extraction electrode 17 by the third DC power supply 18 on the negative side with respect to the ground electrode 13, and the acceleration electrode 12 is applied to the extraction electrode 17 by the second DC power supply 16. Since the accelerating voltage is applied to the positive side with respect to 13, ions of the reactive gas are accelerated by the sum of the extraction voltage and the accelerating voltage, and are extracted from the inside of the internal bath 5 to the substrate 4 side. And

However, since the extraction voltage is applied to the extraction electrode 17 on the negative side with respect to the ground electrode 13, the cutout 17 of the extraction electrode 17 near the ground electrode 13 is applied.
The ions of the reactive gas extracted to a are decelerated by the extraction voltage between the extraction electrode 17 and the ground electrode 13, and as a result, the ions of the reactive gas extracted to the notch 5 a of the internal tank 5 are Acceleration electrode 1 by second DC power supply 16
The substrate 4 is irradiated with kinetic energy given by the acceleration voltage applied to the substrate 2.

As described above, in the above embodiment, the means for accelerating the ions of the reactive gas is constituted by including the extraction electrode 17 in addition to the accelerating electrode 12 and the ground electrode 13. Is accelerated by the extraction voltage in addition to the acceleration voltage, and is extracted from the inside of the internal bath 5 toward the substrate 4. Even when the acceleration voltage is reduced,
Reactive gas ions of a required level or more can be extracted from the internal tank 5. Therefore, since the substrate 4 cannot be irradiated with a certain amount of reactive gas ions, the disadvantage that a thin film of sufficient quality cannot be formed on the substrate 2 is solved.

Further, the ions of the reactive gas are decelerated by the extraction voltage from the extraction electrode 17 to the ground electrode 13, and eventually the reactive gas ions are reduced by the acceleration voltage at the outlet of the inner tank 5. Therefore, a desired thin film corresponding to the acceleration voltage can be formed on the substrate 4.

In the above embodiment, the case where a hydrocarbon film is dissociated to form a carbon film is described. However, in addition to the hydrocarbon gas, a gas containing a silane gas and a nitrogen element is used as a reactive gas. For example, by using a combination of SiH ₄ + NH ₃ or a gas containing a silane gas and an oxygen element, for example, a combination of SiH ₄ + N ₂ O, an SiN thin film,
Alternatively, a similar effect can be obtained when a SiO ₂ thin film or the like is formed.

In the above-described embodiment, the electron beam extraction electrode 10 has a thickness of 10 to 100 in the same manner as the conventional thin film forming apparatus.
It is described that a voltage of V is applied to emit an electron beam of 1 to 5 A.
A similar effect can be obtained even if a voltage of 100 V or more is applied.

[0024]

As is apparent from the above description, according to the present invention, the acceleration means is provided in the ground electrode provided around the notch in the inner tank wall and the reactive gas passage, and An accelerating electrode to which a positive accelerating voltage is applied to the electrode and a reactive gas passage between the accelerating electrode and the ground electrode, and a negative withdrawal voltage applied to the ground electrode It is possible to irradiate the substrate with a certain amount of reactive gas ions even if the acceleration voltage is changed, and to form a desired high-quality thin film corresponding to the acceleration voltage. The effect that it can be obtained is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a thin film forming apparatus showing an embodiment of the present invention.

FIG. 2 is a schematic sectional view of a conventional thin film forming apparatus.

[Explanation of symbols]

1 vacuum chamber 4 substrate 5 inside chamber 5a passage 10 electron cut-out portion 6 nozzles 9 reactive gas beam extracting electrode 11 electron beam emitting means 12 accelerating electrodes 13 grounded electrodes 17 extraction electrode

Claims (1)

(57) [Claims] A vacuum tank and an internal tank are provided. A gas injection nozzle is provided inside the internal tank, and a part of the internal tank wall corresponding to a passage of a reactive gas ejected from the nozzle is cut off. And a substrate is disposed in a vacuum chamber corresponding to a direction in which the reactive gas is ejected, while an electron beam extraction electrode and electron beam emitting means are provided in a direction of passage of the reactive gas in the internal tank, and In a thin film forming apparatus provided with a reactive gas passage in a vessel and a reactive gas ion accelerating means in a notch in the wall surface, the accelerating means is provided around the notch in the inner tank wall. A ground electrode, an acceleration electrode disposed in the passage of the reactive gas, wherein a positive acceleration voltage is applied to the ground electrode, and the reactive gas between the acceleration electrode and the ground electrode. Disposed in the passage, and opposed to the ground electrode. And a lead electrode to which a negative lead voltage is applied.