JPS5812339B2 - Ion etching method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ion etching method for etching a substrate with ions in a vacuum.

In an ion etching apparatus that can etch a substrate in a vacuum, a parallel plate is an apparatus that extracts inert gas ions generated in an ion source in an inert gas such as argon (Ar) and causes them to collide with the substrate for etching. A device that applies direct current or Takaoka wave electric current to an electrode to cause a glow discharge, thereby performing sputter etching.A high-frequency voltage is applied to an electrode on the outer periphery of a vacuum container to cause a glow discharge inside the vacuum container, thereby performing etching. Various etching apparatuses, such as apparatuses for performing etching, are already known.

Vacuum ion etching equipment has the following characteristics: the etching process is simple, it can reduce contamination of the substrate, it can accurately etch fine patterns, and it can etch many substrate constituent materials. be.

However, in conventional high-frequency sputter etching using argon, the practical etching rate is generally 10
It is 0λ/nin.

Should I increase the RF power to further increase the etching speed? However, cracking inevitably involves an increase in the temperature of the substrate, and especially when using a photoresist mask made of an organic material, the mask cannot withstand this temperature increase.

Furthermore, even if the input high-frequency power is increased while ignoring temperature rise and damage to the substrate, it is difficult to increase the etching rate to 1000λ/min or more with the current electrode structure.

This is because conventional electrodes for sputter etching have an upper limit to their ionization rate, making it impossible to utilize dense plasma.

On the other hand, Japanese Patent Application No. 48-89647 proposed the use of fluorochlorinated hydrocarbon instead of argon gas in the electrode structure of the conventional high wave sputter etching as an improvement to the conventional sputter etching method. ing.

This improved etching method provides approximately an order of magnitude higher etching rate under approximately the same conditions as compared to conventional etching.

However, this value is also not sufficient when performing deep etching.

An object of the present invention is to provide an ion etching method that can dramatically increase the etching rate, which has been difficult with conventional ion etching methods.

In the ion etching method according to the present invention, a hollow cylindrical electrode to which a positive or negative voltage can be applied is provided in a fabric container, a fluorochlorinated hydrocarbon gas is introduced into the vacuum container, and a fluorochlorinated hydrocarbon gas is introduced into the hollow cylindrical electrode. The method is characterized in that the fluorochlorohydrocarbon gas is ion-scorched to cause ionized particles to collide with the substrate, thereby increasing the ion etching rate.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a sectional view of an actual example of an ion etching apparatus according to the present invention.

In the figure, a vacuum vessel 11 is evacuated to a vacuum by an evacuation device (not shown) such as a vacuum pump connected via a conduit 12.

Next, fluorochloride hydrocarbon gas is introduced here from the gas introduction pipe 13, and the pressure inside the vacuum container is set to 104 to 10-1 Torr.
Set to .

A portion of the fluorinated chlorinated hydrocarbon gas in this pressure state is ionized within the hollow cylindrical electrode 14 by the voltage applied to the hollow cylindrical electrode 14 by the DC electrode 15 .

Ionized particles of the fluorinated chlorinated hydrocarbon gas ionized within this hollow cylindrical electrode are accelerated toward the substrate 16 having the same potential as the vacuum vessel, etching the substrate.

The insulator 11 is a material that prevents unnecessary discharge and short circuit between the vacuum container 11 and the hollow cylindrical electrode 14.

Hollow electrodes are generally known as hollow anodes or hollow cathodes in the field of vacuum discharge, depending on the potential applied to the electrode.

This structure is not fully understood, but this structure allows extremely efficient ionization and produces a highly dense plasma.

As described above, the chemical reactivity with the substrate 16 by using the fluorochlorinated hydrocarbon gas increases, making it possible to significantly increase the etching rate.

! Figure 2 is a sectional view of another actual case using the method of An's invention.

In the figure, a vacuum vessel 11 is evacuated to a vacuum via a conduit 12.

Next, fluorinated chlorinated hydrocarbon gas is supplied to the 9 substrates 16 in the vacuum container from the air supply pipe 13 via the variable leak valve 23.
, several Torr in the space surrounded by the cylinder 14 and the bottom plate 27.
~ several mTorr.

In this state, when a negative potential is applied to the substrate and the cylinder with respect to the bottom plate by the DC power source 15, the fluorochlorinated hydrocarbon gas is ionized in the space, the ionized particles are accelerated toward the substrate, and the etching.

The plasma density in this space is very high, and the etching rate can be greatly increased by increasing the chemical reactivity with the substrate by using fluorochlorohydrocarbon gas, as shown in the actual case shown in Figure 1. Same as in case.

FIG. 3 shows the electrode structure in another persimmon example according to the present invention.

In the figure, 14 is a hollow cylindrical anode, 15 is a DC power source that applies voltage to the anode, and 16 is a substrate to be etched.

In this case, a large number of cylindrical electrodes 14 are incorporated into one etching apparatus, making it possible to simultaneously etch a large number of substrates.

FIG. 4 shows an electrode structure in another example of leprosy according to the present invention.

As in the case of FIG. 3, it is composed of a large number of cylindrical electrodes, but the difference is that the polarity of the cylindrical electrodes is reversed.

FIG. 5 shows an electrode structure in another actual case according to the present invention.

In the figure, 14 is a hollow cylindrical single pole, 15 is a DC power source that applies voltage to the anode, 16 is an etching substrate, and 51 is a hollow cylindrical anode with both sides open.

This example also allows a large number of substrates to be stored in a single device, making it very effective for mass production.

The following table shows the types of fluorochlorinated hydrocarbons used in accordance with the present invention and the etching rate of silicon using them, in comparison to when argon was used under the same conditions.

As described above, according to the present invention, since the discharge from the hollow cylindrical electrode is utilized, the probability of ionization is very high and the plasma density is high, so the number of ionized particles that collide with the substrate increases, and the etching rate due to the collision increases. Not only does it become extremely toxic, but because it is ionized using fluorochlorohydrocarbon gas, chemical reactions occur between chlorine ions, fluoride ions, etc. generated from the fluorochloride hydrocarbon gas and the substrate constituent materials. This occurs and volatile substances are generated, which has the effect of dramatically increasing the etching rate.

Although a hollow cylindrical electrode was used in the actual winding example of the present invention, this electrode does not have to be cylindrical and may be polygonal, and the walls forming the hollow do not need to be all closed to prevent plasma from leaking. There may be spaces everywhere.

Further, it goes without saying that the potential of the cylindrical electrode may be either positive or negative.

Furthermore, it goes without saying that the same effect can be produced even if plasma is generated within the cylindrical electrode using a high frequency power source as the power source.

[Brief explanation of drawings]

1 to 5 are configuration diagrams of an ion etching apparatus showing first to fifth leprosy methods according to the present invention. In the figure, 11... vacuum container, 12...
... Conduit, 13... Gas introduction pipe, 14...
...Hollow cylindrical electrode, 15...DC power supply, 16.
...Substrate, 17...Insulator, 23...
... variable leak valve, 27 ... bottom plate, 51 ... double-sided open cylindrical electrode.

Claims (1)

[Claims] 1. The substrate is etched using an ion etching apparatus consisting of a vacuum container that can be evacuated, a hollow cylindrical electrode and the substrate g arranged in the vacuum container, and a gas introduction system that introduces etching gas into the vacuum container. An ion etching method for etching, wherein a fluorochlorohydrocarbon gas is introduced into the vacuum container as the etching gas, and a glow discharge is generated within the hollow cylindrical electrode, thereby etching.