JPS63155728A - Plasma processor - Google Patents

Abstract

PURPOSE:To improve the controllability of plasma density and ion energy intensity and the flexibility of a process by applying a microwave and a high frequency wave to processing gas. CONSTITUTION:Processing gas is supplied, and the pressure of a plasma generating vessel 10 is set to a pressure for generating a plasma. A microwave generator 7 generates a microwave to supply it to a microwave matching unit 6, and supplied to a microwave antenna 3. Then, a magnetic field is generated in a plasma chamber 4 to generate a plasma. The plasma acts at a sample 11 placed on a sample base 12 to process an etching, a depositing, a cleaning, etc. An anode 2 is mounted at a place where the electric field of the microwave is weak oppositely to the base 12, and grounded so as to be the same potential as the vessel 10. High frequency power is supplied from a high frequency power source 14 to the base 12. The microwave and high frequency wave can be efficiently applied to the processing gas, thereby improving an ionization efficiency.

Description

[Detailed description of the invention] [Industrial application field] The present invention includes etching, deposition, and cleaning.

It relates to plasma processing equipment such as sputtering.

[Conventional technology]

Plasma processing technology converts processing gas into plasma, and uses ions and active radicals contained in the plasma to process, clean, deposit, and the like on a processed object.

Conventionally, the plasma used in this type of plasma processing apparatus is produced by supplying high-frequency power of 100 KHz to several hundred MHz to electrodes or a workpiece holding table in a vacuum container, or by supplying microwave power of, for example, 2.45 GHz. It was generated by supplying it through a waveguide into a vacuum container that also served as an air conditioning resonator and causing a discharge.

1. A high frequency of 0 kHz to several hundred MHz (hereinafter, high frequencies in this range will be particularly referred to as high frequencies to be distinguished from microwaves).When electric discharge is used, that is, high frequency discharge, plasma can be generated with a simple structure, and plasma can be generated with a simple structure. 100e
Processing using ions with energy below V is possible, but the ionization efficiency is poor (the degree of ionization is around 10-6, and stable plasma generation is difficult at a vacuum level below 1O-3 torr). There is.

On the other hand, when using microwave power, 1O-3
High-density plasma can be generated even at low pressures below torr, and processing with low-energy ions of about 10 to 30 eV is possible, but on the other hand, processing with ions in a wide energy range of 10 to 500 eV is not possible. ,
Another drawback is that it cannot be treated with high-energy ions.

In recent years, there has been an increasing demand for a plasma processing apparatus that can freely set the energy intensity of ions. Therefore, it is an object of the present invention to improve the controllability of the plasma density and the energy intensity of ions by eliminating the drawbacks of the prior art described above. It is an object of the present invention to provide a plasma processing apparatus that can improve the flexibility of the processing process.

[Object of the Invention] It is an object of the present invention to provide a plasma processing apparatus which can eliminate the drawbacks of the above-mentioned conventional examples and at the same time can realize diversification of plasma processing processes.

〔Example〕

1 to 4 show some embodiments of the present invention.
is a processing gas inlet, 2 is an anode electrode, 3 is a microwave supply antenna, 4 is a plasma chamber, 5 is a coaxial tube for microwave supply, 6 is a microwave matching device, 7 is a microwave generator, 8 is a magnetic field generator 9 is a power supply for excitation of the air-core coil; 10 is a container for plasma generation; 11 is a sample to be processed;
2 is a sample holding stand, 13 is an exhaust system, and 14 is a high frequency power source. At the time of sample exchange, the sample holding table 12 is moved to a sample exchange position (not shown) by a drive mechanism (not shown).

First, the first embodiment shown in FIG. 1 will be described. In the above configuration, a gas suitable for processing the material is supplied from the processing waste inlet, and the pressure in the plasma generation container 10 is adjusted to a value suitable for plasma generation by the exhaust system 13.
Set to rr~10-'torr.

A microwave generator 7 normally generates microwaves of 2' or 45 GHz, which are supplied to a microwave matching device 6 through a waveguide or the like, and adjusted so that the reflected waves from the microwave antenna 3 are minimized. . The microwave generator 7 generates microwave power such that the microwave antenna is grounded (grounded) in terms of direct current.

Microwaves are supplied to the microwave antenna 3 through a coaxial tube 5. Figure 3 shows an example of an antenna and coaxial tube. FIGS. 3(a) and 3(b) are external views viewed from different angles. However, here, 3 is a microwave, 31 is a slit, 5 is a coaxial tube, and 51 is an insulator that holds the conductor at the center of the coaxial tube. The antenna shown here is a slot type antenna, commonly called a rigitano coil. The length L of the slit 31 is λ/, where λ is the wavelength of the microwave.
Choose an integer multiple of 2. For example, in the case of 2.45 GHz, assuming 1/2λ, the slit length is 6 cm, and this antenna can be regarded as a TEon mode cavity (resonator). The insulator 51 not only holds the center conductor 51 but also serves as a vacuum seal. Although a coaxial tube is shown here, the same effect can be obtained with a waveguide. An air-core coil 8 is placed heavily around the plasma generation container 10.
is installed, and can generate a magnetic field in the plasma chamber 4. The strength of the magnetic field is such that electrons in the plasma chamber undergo electron cyclotron resonance with microwaves (for example, 2
．． The magnetic flux density for 45GHz microwave is 875Gau.
ss). By doing so, plasma can be generated efficiently, and high-density plasma can be generated even at low pressure (10 -3 torr or less).

The plasma generated in the plasma chamber 4 acts on the sample 11 placed on the sample stage 12, allowing processing such as etching, deposition, and cleaning to be performed.

On the other hand, the anode 2 faces the sample stage 12 and is placed in a place where the microwave electric field is weak, for example, λ/2 from the end of the antenna slit.
It is installed at a location that is an integral multiple of , and grounded so that it has the same potential as the plasma generation container 10. High frequency power of 100 KHz to several hundred MHz is supplied to the sample stage 12 from a high frequency power supply 14 . In practice, the frequency is 100 KHz to 500
KH2 or 13,56 MHz is often selected.

If the microwave leaks toward the high-frequency power source 14, a device for blocking the microwave, such as a unidirectional tube, may be inserted between the sample stage 2 and the high-frequency power source 14.

Since the antenna is placed around the counter electrode to create a space that is close to a closed space, both microwaves and high frequency waves can be efficiently applied to the processing gas within this space, improving ionization efficiency. In addition, the electrode to which high frequency was originally applied is smaller than the other electrode, and when high frequency is applied to the plasma with this electrode arrangement, the electrode to which high frequency was applied, that is, the sample holder 1
A negative bias potential of several tens to hundreds of square meters is generated on the sample 11 placed on the sample 2, and ions in the plasma are accelerated by this potential and collide with the sample 11 to promote the sample processing action. Since this potential depends on the high frequency power supplied, the energy of the ions can be controlled by adjusting the high frequency power. Furthermore, when the frequency of the high-frequency power is low (several hundred kHz or less), when the sample side becomes a negative potential due to the high-frequency power of the ions, and no microwave power is applied, plasma can be generated by high-frequency discharge alone and plasma processing can be performed.

The reverse is also the same; plasma treatment can be achieved using only microwave discharge.

Furthermore, by appropriately selecting high frequency power and microwave power, it becomes possible to diversify the processing. For example, it has the disadvantage that it takes a long processing time. In processing using high-energy ions, the processing effect at the time of collision is large due to the high energy, and the processing time is reduced.In the apparatus of this embodiment, by using both electric powers, it is possible to generate high-density plasma and to generate ions with a wide energy range. When processing is possible and the processing speed is desired to be increased, the controller 100 controls the high-frequency power supply 14 in response to a command from the operator to increase the high-frequency power and increase the number of high-energy ions, causing more damage to the sample. When processing is required, the controller 100 controls the high frequency power source 14 to reduce the high frequency power, and also controls the microwave generator 7 to increase the microwave power to increase the number of low energy ions. The energy state of the generated ions can be adjusted depending on the desired processing conditions.

Controller] 00 is a high frequency power supply 14. The power generated by the microwave generator 7 can be adjusted individually.

Next, FIG. 2 shows a second embodiment. The difference from the first embodiment is that a high frequency power source 14 is connected to the anode electrode 2, and the sample holding table 2 is grounded to the plasma generation container 10, and the other parts are exactly the same as the first embodiment. It is. In this case as well, complex processing can be performed by appropriately adjusting the high frequency power and the microwave power.

Incidentally, the plasma chamber 4 may be covered with SiO2 or the like to prevent contamination caused by etching of electrodes and the like by plasma.

[Effects of the present invention]

As explained above, the present invention makes it possible to diversify treatment processes.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the first embodiment of the present invention, Fig. 2 is a sectional view of the second embodiment, Fig. 3 is a diagram of a slit-type microwave antenna, and Fig. 4 is a third embodiment. FIG. In the figure, 2 is an anode electrode, 3 is a microwave antenna, and 10
1 is a plasma generation container, 1 is a sample, and 12 is a sample holding stand.

Claims (3)

[Claims] (1) a support means for supporting a workpiece; an electrode provided to face the workpiece supported by the support means;
a first high frequency supply means for supplying a first high frequency to only one of the electrode and the support means; A plasma processing apparatus comprising a second high frequency supply means for supplying a second high frequency. (2) The second high frequency supply means has a second high frequency supply antenna provided so as to surround the space between the support means and the electrode. The plasma processing apparatus described in Section 1. (3) The plasma processing apparatus according to claim 1, wherein the second high frequency wave is a microwave.