JP2973058B2 - High vacuum / high speed ion processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion processing apparatus for forming a film on a substrate provided in a high vacuum at a high speed or etching a substrate or a thin film on the substrate at a high speed.

[0002]

2. Description of the Related Art Conventionally, sputtering and ion plating are known as methods for forming a thin film on the surface of a substrate in a vacuum. In addition, the surface of the substrate and the film formed on the surface are removed in a vacuum. Ion etching is known as a technique. In these film formation and etching, the substrate is processed using ions in a plasma of a processing gas such as an Ar gas or an O ₂ gas generated in a vacuum.
It is used for processing substrates in the SI manufacturing process.

One example of an apparatus for sputtering is shown in FIG.
A target b and a film-forming substrate d mounted on a substrate holder c are provided in a vacuum chamber a so as to face each other, and a sputter gas introduction port e and the vacuum chamber a are provided in the vacuum chamber a. An exhaust port f connected to an exhaust system for exhausting the target to a vacuum, and plasma generating means for generating ions for sputtering the material of the target b in the vacuum chamber or outside the vacuum chamber. . This example shows a magnetron sputtering apparatus including a main magnet h for generating a magnetic field g orthogonal to an electric field on the front surface of a target b, and an auxiliary magnet i for setting an optional magnetic field to a non-equilibrium mode,
The plasma generating means comprises a cathode electrode j provided with a target b on the surface facing the substrate d, and an anode electrode using a substrate holder c, and these electrodes are connected to an RF power source k. In many cases, the auxiliary magnet i is not provided. This device was introduced, for example, Ar gas into the vacuum chamber a 10 ^{- 4} was adjusted to a vacuum pressure of about Torr, magnetic field g between the cathode electrode j and the anode electrode of the substrate holder c energized from RF power supply k Generates a magnetron discharge confined to the substrate d, and a thin film of the material of the target b can be formed on the substrate d at a relatively high speed. Although not shown, the main magnet h,
There are also known a sputtering apparatus having no auxiliary magnet i and a sputtering apparatus using a DC power supply instead of the RF power supply k. If the substrate d is attached to the cathode electrode j and plasma is generated in the vacuum chamber a, the substrate d can be etched.

[0004] The sputtering apparatus shown in FIG.
The apparatus is different from the above-described apparatus in that the apparatus includes a plasma generating means based on electron cyclotron resonance (ECR). The ECR plasma generating means includes a microwave waveguide 1 provided outside one end of a vacuum chamber a, a plurality of magnets m provided on the outer periphery of the vacuum chamber a, and a target given a potential for extracting ions. The magnet m forms a gradient magnetic field having a resonance magnetic field of 875 gauss in which a magnetic field is large on the entrance side of the microwave and reduced on the exit side in the portion near the waveguide 1 inside the vacuum chamber a. In advance, when a processing gas such as an O ₂ gas or an Ar gas is introduced into the vacuum chamber a to adjust the pressure, and then a microwave of 2.45 GHz is introduced, the processing gas is turned into plasma to generate ions. Collides with a target n provided with a potential for extracting ions provided in front of the substrate d to sputter the target material, and the sputtered target material is deposited on the substrate d to form a thin film. If a lattice-like ion extraction electrode n is prepared instead of the target b, the substrate d can be etched with ions. In the above sputtering apparatus, a slightly negative bias voltage or a high frequency may be applied to the target in order to increase the sputter yield (sputter rate).

[0005] Recently, the idea of applying helicon waves to plasma processing has been announced (J. Vac. Sc.).
i. Technol. B9 (2), Mar / Apr19
91) However, sufficient practical technical methods have not yet been published.

[0006]

[Problems that the Invention is to provide a device of the conventional sputtering or etching, the pressure inside the vacuum chamber 10 ^{- 4} Tor
r not be operated unless the following relatively low vacuum, 10 ^{- 6}
Operation in a high vacuum of about Torr was difficult. In order to increase the film forming rate or the etching rate in these conventional apparatuses, a processing gas is further introduced into the vacuum chamber to increase the rate.
0 ^{- 1} to 10 ^- had no choice but to operate at ² Torr bad vacuum. It is known that impurities such as water, oxygen, and hydrocarbons are released from the walls of the vacuum chamber, and these have a significant effect on the quality of the film formed on the substrate. Further, the gas utilization efficiency is low at a low vacuum, and most of the gas is discarded as it is or as a secondary product. Some of these impurities and secondary products are mixed into the substrate film as impurities and dust particles,
In the case of an LSI substrate, it adheres to the substrate and causes an undesired short circuit or disconnection of the circuit and a low yield of the product. Semiconductor memory requires fine processing for high integration, and these impurities and secondary products are the biggest factors that hinder fine processing. Generation of such impurities and secondary products is that magnetron discharge, ECR discharge, and the like are generated only in the low vacuum as described above. In these discharges, the ionization efficiency of gas does not reach 10%, and in magnetron discharge, This is due to the restriction from the discharge type itself that it is only a few percent or less.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus capable of performing ion processing for sputtering and etching with less generation of impurities and secondary products. A second object of the present invention is to provide an apparatus capable of sustaining generation of plasma in a high vacuum and having a high ionization rate of a processing gas and capable of high-speed ion processing.

In the present invention, in order to achieve the above object,
In an apparatus for ionizing a processing gas such as an Ar gas or an O ₂ gas introduced into a vacuum chamber by plasma, and performing ion processing of film formation or etching on a substrate prepared in the vacuum chamber with ions generated by the plasma, A high vacuum evacuation system is connected to a vacuum evacuation port of the vacuum chamber , and in front of the substrate and in the vacuum chamber.
Outside, and so Keru set the helical antenna consisting of and high frequency is connected to the oscillation source Rutotomoni helical coil is energized than this has a coil center axis perpendicular to the plate surface of the substrate. The present invention can adopt the configuration described in claim 2 or later for application as a film forming apparatus or an etching apparatus.

[0009]

When the present invention is applied to a magnetron sputtering apparatus, the chamber is evacuated to a high vacuum from a vacuum chamber exhaust port by a high vacuum exhaust system, and a processing gas such as Ar gas is introduced into the chamber to evacuate the chamber. for example 10 ^- it is adjusted to a high vacuum of ⁵ Torr. When the chamber is evacuated, water from the walls of the vacuum chamber
Although impurities such as oxygen and hydrocarbons are released, the release of these impurities decreases when the inside of the chamber becomes a high vacuum.

[0010] When the emission of the impurities stops, an RF power source is connected to the cathode electrode and the anode electrode, and a current having a frequency of several MHz to 13.56 MHz or more is supplied to the helical coil of the helical antenna from the high frequency oscillation source. 10 to the helical antenna in an enclosed space ^-
Despite the high vacuum of ⁵ Torr, high-density plasma is generated, and ions in the plasma sputter a target provided on the cathode electrode. The sputtered target material collides with the substrate and a thin film is formed there. The ionization rate of the processing gas is about 100%. Even if the number of gas molecules decreases due to high vacuum, the ionization rate is high, so the absolute number of ions increases, and the sputtering amount increases accordingly. Since the amount of gas that is not ionized and discarded from the exhaust port is reduced, the amount of secondary products of the processing gas is also reduced. Therefore, high-speed film formation can be performed in a high vacuum with few impurities, and the quality of the film is good and the occurrence rate of defective products is reduced.

[0011] Even when the present invention is applied to an apparatus for performing ion processing for etching, the substrate can be subjected to high-vacuum, high-speed etching processing with little obstacles due to impurities. Further, even if the plasma generating means is replaced with, for example, ECR discharge, ion processing can be performed at high vacuum and high speed.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
FIG. 3 shows an embodiment applied to a magnetron sputtering apparatus. In FIG. 3, reference numeral 1 denotes a gas inlet 2 for introducing an inert gas such as Ar gas or a processing gas for O ₂ gas, and a vacuum exhaust port 3. 1 shows a vacuum chamber provided. Inside the vacuum chamber 1, a cathode electrode 5 connected to an RF power source 4 and a substrate 7 held by a substrate holder 6 are provided to face each other.
A target 8 is provided on the front side. An electromagnet 10 for forming a magnetron magnetic field 9 parallel to the front surface of the target 8 and an auxiliary magnet 11 for setting the magnetic field 9 to a non-equilibrium mode are provided on the rear surface of the cathode electrode 5. Various materials are used for the substrate 7, typically silicon for a semiconductor device, and a thin film of a conductive film or an insulating film is formed on the surface of the substrate 7. The substrate holder 6 was connected to ground so as to serve as an anode.

Although the above configuration is not particularly different from the conventional magnetron sputtering apparatus, in the case of the present invention, the coil center axis 1 crossing the plate surface 7a of the substrate 7 is provided in front of the substrate 7.
Antenna 1 comprising a helical coil 13 having a frequency band 2 and a high-frequency oscillation source 14 connected to the coil 13 and emitting a high frequency of several MHz to 13.56 MHz or more.
5 is provided, 10, such as sputter ion pumps and cryopump to a vacuum exhaust port 3 ^- Connect the high vacuum evacuation system 17 which includes a evacuable high vacuum pump 16 to ⁶ Torr or more.

Although the helical coil 13 is formed by one conductor, it may be formed by coiling a plurality of conductors into two or more coils. The helical coil 13 may be installed at a position in front of the plate surface 7a of the substrate 7, and may be provided not only inside the vacuum chamber 1 as shown in FIG. 4 but also outside the vacuum chamber 1 as shown in FIG. It is possible, as shown in FIG. 6 or FIG. 7, to be provided so as to be shifted toward the substrate 7 or the target 8. When the helical coil 13 is provided outside the vacuum chamber 1, the material of the vacuum chamber 1 must be a dielectric such as quartz or ceramic, or an insulator.
Instead of the helical coil 13, a wavelength reducing antenna such as a Registano coil or a Poswell antenna may be used. Further, a permanent magnet 18 or an electromagnet is provided around the outer periphery of the helical coil 13 to prevent electrons generated in the vacuum chamber 1 from colliding with the chamber wall and disappearing. It is preferable to form a cusp magnetic field or a mirror type magnetic field as shown in FIG. 9 in the vacuum chamber 1 so as to minimize the collision of electrons with the chamber wall.

[0015] Describing the operation of the apparatus shown in FIG. 3, the chamber from the vacuum exhaust port 3 by the high vacuum evacuation system 17 10 ^{- 8} Tor
When evacuated to a high vacuum of about r, water
The impurities such as oxygen release, and introducing a processing gas of Ar gas and the like when the emission decreases from the gas inlet 2 into the room, the inside of the chamber, for example, 10 ^- adjusted to ⁵ Torr in a high vacuum.
Then, the cathode electrode 5 on which the magnetron magnetic field 9 is formed
To the helical coil 13 of the helical antenna 15 and a current having a frequency of several MHz to 13.56 MHz or more from the high frequency oscillation source 14 is applied. When the vacuum chamber is at a high vacuum, the discharge generated between the cathode electrode 5 and the anode substrate holder 6 is usually immediately extinguished, but in the case of the present invention, the discharge in the space surrounded by the helical antenna 15 is performed. to 10 ^{- 5} Torr despite the high density of plasma is high vacuum is generated, approximately 100% of the treated gas is sometimes ionized. Ionization rate can be known by measuring the ionic current flowing through the target 8, conventionally 10 ^{- 5} but Torr in the plasma is not ignited, in the case of the present invention is conventional 10 ^{- 3} Torr
The same amount of ions as in the case of the degree of vacuum is obtained. The ions generated in the plasma are the cathode electrode 5 having a low potential.
And sputters into the target 8 attached to the front surface of the cathode electrode 5 to sputter the material of the target 8, and the sputter adheres to the substrate 7 in a thin film form. The ion amount and the deposition rate are in a proportional relationship, and therefore, in the case of the present invention, 1
0 ^{- 5} Torr in a high vacuum, yet conventional 10 ^{- 3} Torr perform the deposition on the substrate 7 at the same deposition rate as when the impurities so high vacuum, yet ionization rate is high, the occurrence of secondary products And the film quality and yield are improved. Although the details of the reason why the helical antenna 15 contributes to the generation of the plasma have not been elucidated yet, the high frequency is well absorbed by the plasma once generated in a high vacuum and high energy is given to the plasma, so that the plasma discharge is maintained. It is considered that the electrons in the plasma run faster and longer, and the surrounding gas molecules are ionized, thereby increasing the ionization rate.

The embodiment shown in FIG. 10 is an embodiment in which the present invention is applied to a sputtering apparatus utilizing ECR discharge, and its basic configuration is the same as that of FIG. 2, and its plasma generating means is a vacuum chamber. 1. Three magnets 19a, 19b, and 19c provided on the outer periphery of the vacuum chamber 1 for forming a magnetic field for electron cyclotron resonance inside the vacuum chamber 1, and a micro-machine provided at one end of the vacuum chamber 1 through a ceramic window 20. The helical coil 13 of the helical antenna 15, which is constituted by a wave waveguide 21 and a target 22 capable of extracting ions by applying a negative potential, is provided in the discharge part 1 a of the vacuum chamber 1. are, such as sputter ion pumps and cryopump to a vacuum exhaust port 3 10 ^{- 6} high vacuum evacuation system 1 having the evacuable high vacuum pump 16 above Torr
7 is connected. In this case, to perform deposition on the substrate 7, the working now vacuum chamber 1 a high vacuum evacuation system 17 10 ^{- 8} T
was adjusted to about ⁵ Torr, ^- the pressure 10 from the gas inlet port 2 After evacuated to a high vacuum of orr while introducing Ar gas or O ₂ gas
When the helical antenna 15 is operated and microwaves are introduced from the waveguide 21 into the discharge unit 1a, the discharge unit 1a
A high-density plasma is generated in the inside, and ions in the plasma collide with a target 8 having a low potential to be sputtered, and the sputtered material of the target 8 adheres to the substrate 7 in a thin film form. Typically 10 ^- Although the microwave discharge is not sustained in a high vacuum of ⁶ Torr, helix antenna 15 as in the present invention
, Microwave discharge having an ionization rate as high as 100% can be performed.

[0017]

[0018]

As described above, in the present invention, a high vacuum exhaust system is connected to a vacuum exhaust port of a vacuum chamber of an apparatus for performing film forming or etching ion processing on a substrate with ions of a processing gas. A coil center axis intersecting the plate surface of the substrate in front of the substrate and connected to a high-frequency oscillation source;
A helical antenna consisting of energized helical coils is provided, so high-density plasma can be generated in a high vacuum and the ionization rate can be greatly improved. Since there are few impurities and secondary products, there is an effect that the ion treatment can be performed with good film quality and little occurrence of defective products due to dust.

[0019]

As described above, in the present invention, a high vacuum exhaust system is connected to a vacuum exhaust port of a vacuum chamber of an apparatus for performing film forming or etching ion processing on a substrate with ions of a processing gas. Since a helical antenna having a coil center axis crossing the plate surface of the substrate and having a helical coil connected to a high-frequency oscillation source is provided in front of the substrate, high-density plasma can be generated in high vacuum. The ionization rate can be greatly improved, the film formation or etching ion processing can be performed at high speed in a high vacuum, and the ion processing can be performed with less impurities and secondary products, resulting in good film quality and less occurrence of defective products due to dust. And so on.

[Brief description of the drawings]

FIG. 1 is a cutaway side view of a main part of a conventional magnetron sputtering apparatus.

FIG. 2 is a cutaway side view of a main part of a conventional ECR type sputtering apparatus.

FIG. 3 is a cutaway side view of a main part of an embodiment in which the present invention is applied to a magnetron sputtering apparatus.

FIG. 4 is a sectional side view of a modification of FIG. 3;

FIG. 5 is a cutaway side view of a second modification of FIG. 3;

FIG. 6 is a cutaway side view of a third modification of FIG. 3;

FIG. 7 is a sectional side view of a fourth modification of FIG. 3;

FIG. 8 is an explanatory diagram of an example of a magnetic field applied to the apparatus of the present invention.

FIG. 9 is an explanatory diagram of another example of the magnetic field applied to the apparatus of the present invention.

FIG. 10 is a cutaway side view of a main part of an embodiment in which the present invention is applied to an ECR type sputtering apparatus .

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields investigated (Int. Cl. ⁶ , DB name) C23C 14/00-14/58 C23F 4/00 H01L 21/203 H01L 21/3065

Claims (9)

(57) [Claims] 1. A processing gas such as an Ar gas or an O ₂ gas introduced into a vacuum chamber is ionized by plasma, and ions generated thereby are subjected to film forming or etching ion processing on a substrate prepared in the vacuum chamber. In the apparatus, a high-vacuum exhaust system is connected to a vacuum exhaust port of the vacuum chamber, and in front of the substrate ,
One outside the vacuum chamber, Rutotomoni which is connected to and the high-frequency oscillation source has a coil center axis perpendicular to the plate surface of the substrate
Helical Antenna Consisting of Helical Coil Energized
High vacuum and high-speed ion processing apparatus characterized by setting digit of. 2. A target and a substrate for film formation are provided in a vacuum chamber so as to face each other. The vacuum chamber has an inlet for sputter gas and an exhaust port connected to an exhaust system for evacuating the vacuum chamber. In a film forming apparatus provided with plasma generating means for generating ions for sputtering the material of the target outside the vacuum chamber or outside the vacuum chamber, a side surface of a space between the target and the substrate is provided. Connect the surroundings to a high-frequency oscillation source
A high-vacuum / high-speed ion processing apparatus, wherein a high-vacuum exhaust system is connected to the exhaust port by being surrounded by a helical antenna composed of a helical coil energized by this . 3. The plasma generating means comprises a cathode electrode provided with a target on a surface facing the substrate, a conductor or a chamber wall of a vacuum chamber made of a conductor or an anode electrode of a substrate holder. 3. The high-vacuum / high-speed ion processing apparatus according to claim 2, wherein said electrode is connected to a DC or RF power supply. 4. A plasma generating means comprising: a cathode electrode having a magnet attached to a surface facing the substrate and having a magnet forming a magnetron magnetic field on the surface; and a conductor or a vacuum chamber made of a conductor. The high-vacuum / high-speed ion processing apparatus according to claim 2, comprising an anode electrode on a wall or a substrate holder, and connecting these electrodes to a DC or RF power supply. 5. A substrate for sputtering or etching at a cathode potential is provided in a vacuum chamber, and an inlet for a sputtering or etching gas and an exhaust port connected to an exhaust system for evacuating the vacuum chamber are provided in the vacuum chamber. Is established,
In a sputtering or etching apparatus provided with a plasma generating means for ionizing the sputtering or etching gas outside or inside the vacuum chamber, a side periphery of a space in front of the substrate is connected to a high frequency oscillation source. A high-vacuum / high-speed ion processing apparatus, wherein a high-vacuum exhaust system is connected to the exhaust port by being surrounded by a helical antenna composed of a helical coil energized by this . 6. The plasma generating means comprises a cathode electrode on which the substrate is mounted and an anode electrode on a chamber wall of a conductor or a vacuum chamber made of a conductor, and these electrodes are connected to a DC or RF power supply. The high-vacuum / high-speed ion processing apparatus according to claim 5, wherein: 7. The plasma generating means includes: a cathode electrode having a magnet mounted on the substrate and forming a magnetron magnetic field on the front surface of the substrate; and an anode electrode on a chamber wall of a vacuum chamber made of a conductor or a conductor. The high vacuum / high speed ion processing apparatus according to claim 5, wherein the electrodes are connected to a DC or RF power supply. 8. The plasma generating means includes a magnet for forming an electron cyclotron resonance magnetic field inside a vacuum chamber, a microwave introduction tube for introducing microwaves into the vacuum chamber, and an ion extraction electrode. The high-vacuum / high-speed ion processing apparatus according to claim 2 or 5, wherein: 9. The high vacuum / high speed ion processing apparatus according to claim 2, wherein a magnet for forming a mirror magnetic field or a multi-pole cusp magnetic field is provided on an outer periphery of the helical antenna.