JPS62130286A - Method and apparatus for dry etching - Google Patents

Abstract

PURPOSE:To etch all samples including insulators and magnetic materials with good accuracy by etching the sample by the high speed atomic rays released from a neutralizing means in a vacuum vessel connected to a particle ray lead- out port of a cathode case enlosing an anode. CONSTITUTION:A prescribed degree of vacuum is attained in the vacuum vessel 18 and an inert gas or active gas is introduced into the cathode case 8 through an introducing port 6 to attain the prescribed degree of vacuum therein. Glow discharge is generated between the anode 10 and the cathode 9 when the poten tial of the anode 10 is maintained at a higher potential than the cathode 9. The electrons released from the latter are then accelerated toward the former and are bombarded by Barkhausen-Kurz oscillation against the gaseous particles in the case 8, by which plasma is formed. The positive ions therein are accelerat ed and are made incident through the particle ray lead-out port 12 on the neu tralizing means 13 so as to collide against the side wall thereof to form high speed atomic rays which are radiated from the means 13. The chargeable particles therein are deflected by a deflecting electrode 14 and the sample on a stage 15 is sputtered and etched only by the non-chargeable high speed atomic rays.

Description

[Detailed Description of the Invention] <Industrial Application Fields> The present invention is a dry kneeching method for etching all solid materials (hereinafter simply referred to as "sample") such as insulators, magnetic materials, semiconductors, metals, and polymers. and regarding equipment.

<Prior Art> As a conventional etching method of this type, a method is known in which a sample surface is etched with a charged particle beam, such as an ion beam. The apparatus used in this ion beam etching method is an etching apparatus using a Kaufmann type ion source, and is an etching apparatus using the Journal Op Electrochem Cuff 1.
Journal of Electr
chemical) Volume 129, No. 5, No. 585-5
Chi, published on page 81 (1982).

M, Mayer (T, M, Mayer) and R.

A paper co-authored by R.A. Banker: Reactive Ion Beam with CF4: Characterization of a Kaufmann Ion
Source and Details of 5i02 Etching (Reactive Ion Beam with C
Fa:Characterization of a
Kaufman Ion 5source and Det
As shown in Ails of 5i02 EtchingJ and shown as an example, as shown in FIG.
It is composed of an electromagnet 5, a gas inlet 6, a sample stage 7, and a vacuum container 8. The vacuum container 8 was maintained in a vacuum atmosphere by a vacuum evacuation pump, and the sample surface was etched.

Among the above devices, a thermionic emission cathode 1, an anode 2,
The cathode 3, extraction electrode 4, and electromagnet 5 are generally collectively referred to as an ion source.

To operate this device, first, the inside of the vacuum container is made into a vacuum atmosphere of 10 to 10 Torr using a vacuum evacuation pump to remove residual gas components, and then a desired gas, such as CF4. Introducing gas into the vacuum container 10
Create a gas atmosphere of ~10 Torr. In this state, a direct current voltage is applied between the thermionic emission cathode 1 and cathode 3 and anode 2 to generate glow discharge.

At this time, the thermionic emission cathode 1 emits thermionic electrons through the filament, making it easy to cause discharge. Also,
The electromagnet 5 functions to more effectively perform a discharge that rotates electrons present in the ion source using an electromagnetic field, thereby increasing the discharge current.

Gas molecules within the ion source are separated into ions and electrons by the glow discharge generated between the thermionic emission cathode 1 and the cathode 3 and the 7 node 2. Then, the ions are extracted as an ion beam by the extraction electrode 4, and the sample stage 7
This is an etching version of the sample above.

<Problems to be Solved by the Invention> However, the method of etching a sample with a charged particle beam using the above-mentioned etching apparatus has the following problems.

is difficult due to charge-up caused by the ion beam on the sample surface.

Further, although this charge-up can be eliminated by electron beam irradiation, it is difficult to perform etching while completely maintaining the surface potential of the sample at zero. This particularly had a negative effect on the precision of fine pattern etching for VLSIs and the like.

This invention eliminates these drawbacks of conventional dry etching methods using ion beams and charged particle beams, and provides a dry etching method that can accurately etch all kinds of samples such as insulators, magnetic materials, semiconductors, metals, and polymers. This is what we are trying to provide.

Another object of the present invention is to provide a dry etching apparatus for carrying out such a dry etching method.

<Means for Solving the Problems> In order to achieve the above-mentioned object, the present inventors etched the sample with a non-charged high-speed atomic beam instead of etching the sample with a conventional charged particle beam. was able to complete. The dry etching method of the present invention is characterized in that a sample is sputtered and etched using a high-speed atomic beam in a vacuum atmosphere.

In other words, there is a cathode case formed on both sides of the anode at a certain distance from the anode and surrounding the anode, a particle beam outlet formed on one side of the cathode case, and a neutral case connected to the particle beam outlet. a process for preparing an apparatus in which a charged particle deflection means is disposed in a vacuum vessel and includes a neutralization means and a charged particle deflection means extending from a tip of the neutralization means;
a process of placing a sample in the vacuum container; a process of evacuating the vacuum container; a process of then introducing an inert gas and/or an active gas into the cathode case; and raising the anode potential higher than the cathode potential. Process: After a process of deflecting charged particles by a charged particle deflection means, the sample is sputtered and etched using a high-speed atomic beam emitted from a neutralization means.

Further, in this dry etching method, while the sample is being sputtered with the high-speed atomic beam, the sample may be rotated and/or moved laterally and reciprocated in a rectilinear motion relative to the direction of the high-speed atomic beam.

In addition, the dry etching apparatus of the present invention has a cathode case formed on both sides of the anode at a constant distance from the anode and surrounding the anode, a particle beam extraction port formed on one side of the cathode case, and a particle beam extraction port formed on one side of the cathode case. The neutralization means connected to the outlet, the charge deflection means provided extending from the tip of the neutralization means, and the sample stage provided below the neutralization means are housed in a vacuum container. This is a characteristic feature.

Further, the sample stage of this dry etching apparatus may be provided with means for rotating and/or transversely reciprocating and rectilinearly moving the high-speed atomic beam emitted from the neutralization means.

<Function> As described above, the etching method and apparatus of the present invention are configured to sputter the sample with a high-speed atomic beam, so that even if the sample is an insulating material, the etching of the sample is easy. For example, there is no difficulty due to charge-up caused by the ion beam.

@ Furthermore, since the atomic beam is made to enter the sample through the charged particle deflection means provided behind the neutralization means, the charged particle beam contained in the emitted beam is removed, and only the purified high-speed atomic beam is delivered to the sample. can be irradiated.

Furthermore, during sputtering with a high-speed atomic beam, the sample is rotated and/or moved in a lateral reciprocating motion with respect to the direction of incidence of the high-speed atomic beam, so that the surface of the sample can be etched uniformly.

<Example> Next, the contents of a dry etching method will be specifically explained based on a dry etching apparatus according to an example of the present invention.

Figure 1 shows the schematic structure of the dry etching apparatus according to the embodiment [#M8
-Mo1 Ichiana Kojugun hh-h Levy μm 0°Both end faces are configured as cathodes 9, and the sword 9 on the side of the parentheses is grounded. In addition, the cathode case 8 is provided with a gas inlet 6, and the hollow interior of the cathode case 8 is provided with round rod-shaped anodes 1o, 1o, which are connected to a power source 11 outside the cathode case 8. On the other hand, a particle beam extraction port 12 is arranged on one side of the cathode 9, and a grid cathode 9a is arranged in the particle beam extraction port 12. For example, a hollow cylindrical body is connected as the neutralization means 13,
Charged particle deflection means 14 is provided below the neutralization means 13, and further below these, a sample stage 15 is placed in the same vacuum vessel 18 and rotates and/or rotates with respect to the incident high-speed atomic beam.
Alternatively, it is provided so as to be capable of reciprocating and rectilinear movement in the lateral direction.

A sample is normally placed on a sample stage 15.

This device is used as follows. First, the vacuum container 18
Activate the oil diffusion pump 20 and oil rotary pump 22 connected to the vacuum container 18 to 10' to 10-' Torr.
- After introducing an inert gas or an active gas into the cathode case 8 from the gas inlet 6 to create a degree of vacuum of about 10-1-1 O-2 Torr, the anode 10 is connected to the cathode 9.
is maintained at a high potential of several hundred volts to several kilovolts. Then,
Anode 10. A glow discharge occurs between the cathodes 9.

At this time, the electrons emitted from the cathode 9 are accelerated toward the anode 10, pass through the middle of the two anodes 10, reach the cathode 9 on the opposite side, lose speed, and return to the anode 1θ side that they passed through. This vibration of electrons, which repeats the above-mentioned reciprocating motion as they are accelerated, is a high-frequency vibration called the Barkhausen-Krull vibration.
This occurs between the cathodes 9 and 9 with O as the center, and the oscillating electrons collide with gas molecules in the cathode case, effectively forming plasma. The Φ ions in the formed plasma are attracted to the cathodes 8 and 9, accelerated, and enter the cylindrical neutralization means 13 through the single-particle beam extraction port 12. When the ion beam incident on the neutralization means 13 collides with the side wall in the neutralization means 13, it combines with secondary electrons generated by the ion bombardment from the side wall, is neutralized, and becomes a high-speed atomic beam. Further, when the ion beam collides with the neutralization means 13, charges may be exchanged and the ion beam may become a high-speed atomic beam. Furthermore, near the cathode 9, where the electrons performing Barkhausen-Krull oscillations have a velocity of zero,
It combines with ions and neutralizes them, creating high-speed atoms. By such a mechanism, the ion beam becomes a high-speed atomic beam and is emitted from the neutralization means 13 into a vacuum.

The material for the neutralization means 13 is preferably one that has a high secondary electron emission ratio and a low sputtering rate. This is because if the secondary electron emission ratio is high, the probability of recombining with ions to form high-speed atoms increases, and it is possible to prevent contamination by atoms constituting the neutralization means. In this example, the secondary electron emission ratio is as high as about 0.5, and the sputtering rate is 0.1.
The neutralization means 13 was made of sintered graphite with a low degree of carbonation.

Further, in this embodiment, two wooden rod-shaped anodes were used as the anode 10, but if it does not interfere with atoms making Barkhausen-Krug vibrations or ions accelerating toward the cathodes 9, Other shapes can be used. Further, in this embodiment, the particle beam extraction port 12 and the neutralization means 13 are provided only in the cathode 9, but the present invention is not limited to this, and they may be provided in both cathodes 9, 9.

Next, the neutralization rate actually measured for the high speed atomic beam source device of the above example will be explained. However, the neutralization rate refers to the proportion of high-speed atomic beams in a particle beam consisting of ion beams and high-speed atomic beams extracted from the source when Ar gas, which is an inert gas, is introduced into the high-speed atomic beam source device.

The device shown in Figure 2 was used to measure the carbonation rate. In this device, two sulins (23 and 24) are installed in parallel on the outlet side of the neutralization means 13, and these sulins (23 and 24) are installed in parallel.
Parallel plate type deflection electrodes 25 and 26 are arranged above and below between 23 and 24, and by changing the voltage Vd applied to the deflection electrodes 25 and 26, the current i flowing to the collector 27 is controlled. If we assume that no electrons are included, then the neutralization rate Rnol can be expressed by the following equation (1).

However, No is the converted ion current value of high-energy particles flowing into the collector, N is the ion beam current value flowing into the collector, δ is the secondary electron emission ratio, io is the collector current when the deflection voltage Vd=O, id is the saturation value of the collector current when the deflection voltage is applied.

FIG. 3 shows the change in collector current i when the deflection voltage Vd is changed. When this experimental result is substituted into equation (1), the carbonation rate Rno=80%. (δ=
0.1) That is, 80% of the beam emitted from the neutralization means 13 is non-charged A "fast atoms" and the remaining 20% is Ar" ion beam.

As shown in the dry etching apparatus of the embodiment (FIG. 1), a deflection electrode is placed immediately after the neutralization means 13! 4, and 20% of A in the total beam as determined from the graph in Figure 3.
The r-ion beam 17 is deflected by a deflection electric field so that it does not irradiate the sample. That is, sample 15 contains Ar
Only 1B of high and distant atomic beams are irradiated.

Since the dry etching apparatus has such a structure, the sample on the sample stage 15 is dry etched mainly by non-charged high speed atoms.

Therefore, regardless of whether the sample is composed of an insulating material or a magnetic material, the surface of the sample can be etched by impacting it with constant energy without being hindered by the sample surface potential.

Figure 4 shows an experimental example in which a mixed gas of CF4 and 02 was introduced into the apparatus shown in Figure 1 to perform reactive high-speed etching of a Si substrate. There is. With the etching apparatus according to the present invention,
This shows that etching is achieved using only non-charged particles. Also, gas flow rate ratio CF4/CF4+ 02=
0.85 allows maximum etching speed.

Next, using the dry etching apparatus of this embodiment, 5i etching was performed.
An example in which a 5i02 fine pattern is formed on a 02 substrate using a fine pattern mask will be described.

The fine pattern mask used to form the pattern on this 5i02 substrate had a thickness of 50 mm on the surface of the 5in2 fused silica substrate.
This is a pattern mask having the structure shown in FIG. 5(a) in which a Cr thin film pattern is formed.

Then, the 5i02 fused silica substrate on which the Cr thin film pattern was formed was irradiated with a high-speed atomic beam using a (CF, +02) mixed gas in a vacuum of 10 Torr at an etching rate of about 100 people/sin. A fine pattern shown in FIG. 5(a) could be formed. However, No. 5(b) is a scanning electron S microphotograph, and judging from this photograph, it was found that a fine vertical pattern with good accuracy could be obtained. Note that the jagged edges in the photograph are due to the Cr mask, and the fact that these are also transferred shows that the dry knee and chinking method of the example is carried out with extremely high accuracy.

<Effects of the Invention> As is clear from the above description, according to the present invention, etching proceeds without being affected even when the sample is an insulator or a magnetic material, or even when a potential is intentionally applied.

In addition, since non-charged particles such as charged deflection means are used, the straightness is very good, so if this is used for forming fine patterns for VLSI etc., it has the advantage of forming highly accurate vertical patterns.

Application fields include semiconductor device manufacturing such as ultra-LSI, f
The manufacturing of ji-based elements has the advantage of being applicable to many fields.

[Brief explanation of the drawings] Schematic configuration diagram of the neutralization rate measuring device in the atomic beam source, Part 3
The figure is a characteristic diagram showing the relationship between deflection voltage and collector current in the carbonation rate measuring device of FIG. 2. A characteristic diagram showing the relationship between the gas flow rate ratio and the etching rate of the sample (Si02 or Si), FIG. 5(b) is a scanning electron microscope photograph showing the state of the substrate surface after pattern formation and etching, and FIG. 6 is a schematic diagram of a conventional dry etching apparatus. In the drawings, 6... gas inlet, 8... cathode case, 9... cathode, 9a... grid cathode, 10... anode, 11... external power supply, 12... particle beam Outlet port, 13...Neutralization means, 14...Charged particle deflection means, 15...Sample stage, 18...Vacuum container. Fig. 2 Fig. 3 Deflection voltage (kV) Fig. 4 Flow 3i ratio (CF4/CF4+02) Fig. 5 Engraving of discharge page 7 (no change in content) Fig. 5 (b) Procedural amendment March 1986 26th

Claims (5)

[Claims] (1) A cathode case formed on both sides of the anode at a constant distance from the anode and surrounding the anode, a particle beam extraction port formed on one side of the cathode case, and an interior connected to the particle beam extraction port. a process of preparing an apparatus in which a neutralization means and a charged particle deflection means provided extending from the tip of the neutralization means are provided in a vacuum container; a process of placing a sample in the vacuum container; a process of evacuating the inside of the container; a process of then introducing an inert gas and/or an active gas into the cathode case;
The method is characterized in that the sample is etched by sputtering with a high-speed atomic beam emitted from a neutralization means after a process of making the anode higher than a cathode potential; and a process of deflecting charged particles by a charged particle deflection means. Dry etching method. (2) In the dry etching method, the etched side of the sample is sputtered with a high-speed atomic beam through a pattern mask, and the same pattern as the pattern of the pattern mask is transferred onto the sample surface. (
The dry etching method described in section 1). (3) In the dry etching method, while sputtering the sample with the high-speed atomic beam, the sample is rotated and/or laterally reciprocated and rectilinearly moved with respect to the incident direction of the high-speed atomic beam. Dry etching method described in ). (4) A cathode case formed on both sides of the anode at a constant distance from the anode and surrounding the anode, a particle beam extraction port formed on one side of the cathode case, and a medium connected to the particle beam extraction port. Dry etching characterized in that a neutralizing means, a charged particle deflection means provided extending from the tip of the neutralizing means, and a sample stage provided below the neutralizing means are housed in a vacuum container. Device. (5) The dry etching apparatus according to claim (4), wherein the sample stage within the vacuum container is provided with rotational and/or reciprocating linear motion drive means.