JPH02297931A - Vapor-phase etching method - Google Patents

Abstract

PURPOSE:To perform anisotropic etching of width of diameter of submicron by plasma glow discharging reactive gas by an electric field via electrodes between boards in a reactive space of predetermined degree of vacuum by a turbo molecular pump. CONSTITUTION:A reactive space 1 is held under pressure of 1-10<-4>Torr by regulating discharge via a turbo molecular pump 9. Product gas from a gas doping system 13' activated by the energy of nonproduct gas such as argon gas activated by electromagnetic force in a resonance space 2 is plasma glow discharged by high frequency or DC energy to be applied while applying a bias via a power source 6 between the electrode 20 of the isolating face side of the board 10 and the electrode isolated therefrom. Thus, the board 10 can be anisotropically etched at the width or diameter of submicron.

Description

Detailed Description of the Invention Field of Application of the Invention 1 The present invention utilizes electron cyclotron resonance to activate or decompose a reactive gas for etching while exhausting unnecessary reactive gas using a turbo molecular boss. The present invention relates to a vapor phase etching method in which a substrate or a material to be etched on a substrate is anisotropically etched by simultaneously applying a high frequency or direct current electric field perpendicularly to the surface of the substrate to be etched.

"Prior Art 1" As an etching technique (vapor phase chemical removal method) using a gas phase etching reaction, a plasma etching method (glow discharge etching method) in which a reactive gas is activated by a high frequency or a direct current electric field is known.

However, in the anisotropic etching method using such glow discharge, the anisotropy of the film is insufficient compared to the progress of VLSI (furthermore, there is a need to further improve the accuracy of the anisotropic etching). Ta.

On the other hand, an etching method using electron cyclotron resonance is known. However, although such a method allows etching of the entire film, it is insufficient for selective anisotropic etching. This is because the reactive gas moves parallel to the substrate surface due to resonance, so it is almost impossible to form it in a recess.In addition, when creating resonance, for example, if argon is used as the resonant atom and the frequency is set to 2.45 GIIz, Requires a strong magnetic field of 875 Gauss. For this reason, the air-core coil that acts on the magnetic field tends to be large, making it impossible to spread the excited gas over a large area. As a result, it has a width or diameter of submicron (less than 1μ, e.g. 0.2μ),
Hole-like etching with a depth of 2 to 4 microns was not possible at all.

Means to Solve the r Problem" In order to solve these problems, the present invention uses cyclotron resonance to activate the reactive gas.

Therefore, activation, decomposition, or reaction of the reactive gas for etching can be carried out extremely efficiently using electrons or activated gas. This active gas is introduced into the atmosphere where the glow discharge is occurring, and the resonance energy is released (
The purpose is to maintain the active state even after the etching has occurred, and to give directionality to the electric field by making it perpendicular to the substrate, thereby anisotropically etching the substrate or the material to be etched on the substrate. It is possible to have a sufficiently deep recess even at a submicron level.

1 effect.'' This plasma glow discharge technology spreads the active gas over a wide space, allowing a large amount of highly accurate anisotropic etching to be performed locally over a wide area of the substrate or the material to be etched on the substrate. It becomes possible to perform the process uniformly without any variation.

In the present invention, a DC power source was used as the glow discharge power source. However, even with high-frequency glow discharge, the excited state of the excited reactive gas can be maintained, and anisotropic etching can be performed by the self-bias created at the same time.

Furthermore, cyclotron resonance uses an inert gas or a non-product gas (a gas that itself produces only a gas when decomposed or reacted). Argon is a typical inert gas. However, helium, neon, or krypton may also be used.

The non-product reactive gas for etching is CF.

CFJz, CFH+, CFJ, CCl4. Nitrogen fluoride (N
F3. N2F6), hydrogen fluoride (HF), fluorine (h),
Typical examples include hydrogen chloride (01CI), chlorine (ch), or a mixture of these with a carrier gas or oxygen.

These non-product etching gases are activated by cyclotron resonance, mixed with the product gas in a reaction space outside the resonance region, and excitation energy is transferred to the product gas. As the etching gas receives an extremely large electromagnetic energy, the etching gas can be activated or decomposed by approximately 100 χ, and is accelerated by the electric field for anisotropic etching and etched onto the substrate at a predetermined angle, generally perpendicular to the substrate. collides with and causes an etching reaction. Furthermore, rooms 'a~3
By heating the substrate at a temperature of 0.000C, the substrate or the material to be etched on the substrate can be anisotropically etched.

The present invention will be illustrated below with reference to Examples.

Example 1 FIG. 1 shows an outline of a cyclotron resonance type plasma etching apparatus of the present invention.

In the drawing, a stainless steel container (1°) has a lid (1") and constitutes a reaction space (1). This container (1°) has a substrate (10) on the top and a substrate holder (10'). A halogen lamp heater (7) is installed on the back side of the lid (1"), and when mounting the board, open I (1") upwards. Infrared rays are emitted through the quartz window (19). The substrate is irradiated and heated.Furthermore, one mesh electrode (20°) is provided on the back side of this substrate, and the other mesh electrode (20) is provided at the bottom of the container (1°). Alternatively, a 13.56 MHz or DC electric field is applied from a DC power source (6).The substrate (10) is positioned perpendicular to this electric field in FIG.

In addition, the non-product gas is extracted from the doping system (13) (18)
It is then supplied to the resonant space (2) made of a quartz tube (29). This resonant space has an air-core coil (5) outside it.

(5゛) and apply a magnetic field. At the same time, for example, 2.4
5 GHz microwave is supplied to the resonant space (2).

In this space, when the non-product gas is argon, a magnetic field (for example, 875 Gauss) determined by its mass and frequency is applied by an air-core coil in order to cause resonance.

For this reason, the argon gas is excited and resonates at the same time as it is binned by the magnetic field, and after being sufficiently excited, the reaction space (1
) is released as electrons and excited argon gas (21
) to be done. At the outlet of this space, etching gas is discharged (22) through a doping system (13°) system (16) by a plurality of ring-shaped nozzles (17). the result,
The etching gas (22) is excited and activated by the non-product gas (21). In addition, a pair of electrodes (20)
, (20') is simultaneously applied to these reactive gases.

As a result, the activated gas flies along this electric field,
The substrate can be selectively etched.

In addition, in order to sufficiently spread the reactive gas in the reaction chamber and to activate the cyclotron, the pressure in the reaction space (1) and resonance space (2) is set to 1 to 10-4 torr, for example 0.03 to 0.001.
It was set to torr. This pressure was achieved by adjusting the displacement of the vacuum pump (9) using a turbo pump together with the control valve (14) of the exhaust system (11).

Experimental Example 1 In this experimental example, Example 1 was used, and a silicon semiconductor was etched using fluorinated nitrogen.

That is, the pressure in the reaction space was 0.003 Lorr, and argon was supplied as a non-product gas from (18) at a rate of 50 cc/min.

In addition, NF3 was supplied from (16) at 20 cc/min. A high frequency electric field of 13.56 MHz to which a self-bias was added was applied as an electric field. The microwave had a frequency of 2.45 GIIz and was adjusted with a power of 30-500-, for example 200-. The resonance intensity of the magnetic field (5), (5°) is 875
Gaussian.

The substrate (lO) was a silicon semiconductor whose upper surface was selectively coated with photoresist. This non-single crystal semiconductor, such as an amorphous silicon semiconductor, is removed and unnecessary gases are discharged from the exhaust system (11). As a result, it was possible to obtain an etching speed of 15 people/second. This speed is three times faster than the 5 per second obtained with plasma etching alone. Furthermore, by cutting a resist pattern with a width of 0.3μ on this silicon substrate, it was possible to obtain anisotropic etching with a width of 0°3μ and a depth of 4μ.

Furthermore, it is effective to remove the reactive gas after anisotropic etching, introduce oxygen instead, and remove the resist remaining on the second surface by ashing after this etching.

r Effect 1 As is clear from the above description, the present invention can perform anisotropic etching of a large area substrate or a material to be etched on a substrate with extremely little damage to the surface to be etched. Ta. In addition, since cyclotron resonance is used, a high etching rate can be obtained.

The etching method of the present invention is applied to semiconductor devices such as photoelectric conversion devices, light emitting devices, old S, FET (field effect semiconductor devices),
It can be fully applied to SL elements (super lattice elements), IlO T elements, and very large scale integrated circuits. Furthermore, the present invention is also effective for other live conductor lasers or optical integrated circuits.

In the etching method using cyclotron resonance of the present invention, it is effective to simultaneously apply optical energy and perform optical etching. In particular, it is effective to use an excimer laser (wavelength: 100 to 400 nm), argon laser, nitrogen laser, etc. as a light source instead of a low-pressure mercury lamp, and select a resonant wavelength.

In the present invention, the substrates to be etched are mainly silicon semiconductors, glass substrates, and stainless steel substrates. However, in addition ■-■ compounds such as GaAs
, GaAlAs, InP, GaN, aluminum, and silicide metals may also be used.

Furthermore, the etching method of the present invention etches not only single crystal semiconductors but also non-single crystal semiconductors, such as amorphous semiconductors.
) as well as 5iGei-x (0<X<1), 5iOz
-x (0<X<2), 5ixC+-x (0<X<1)
, 5kJ4-x (0<X<4).

Further, in FIG. 1, the substrate may be in a lower or vertical structure, and the cyclotron and electric field may be emitted downward or laterally from the upper direction.

[Brief explanation of the drawing]

FIG. 1 shows a cyclotron resonance type plasma etching apparatus of the present invention.

Claims (1)

[Claims] 1. In order to introduce a reactive gas for etching that generates a halogen element into a container having a reaction space, and to maintain the pressure inside the container at 1 to 10^-^4 torr,
By evacuating unnecessary reactive gas while adjusting the exhaust volume using a vacuum evacuation system using a turbo molecular pump, one electrode disposed on the back surface of the substrate and the other disposed apart from the electrode are separated. A submicron (1 μm or less) width or diameter is formed on the substrate or the material to be etched on the substrate by causing a plasma glow discharge of the reactive gas by applying high frequency or direct current energy while applying a bias between the substrate and the electrode. A vapor phase etching method characterized by performing anisotropic etching. 2. A resonant space that generates cyclotron resonance is formed inside the air-core coil by supplying microwaves, and a reactive gas for etching that generates a halogen element is contained in a container that has a reaction space connected to this resonant space. was introduced, and the pressure inside the container was increased to 1 to 10^-^.
In order to maintain the pressure at 4 torr, one electrode disposed on the back side of the substrate is separated from the other electrode by adjusting the exhaust volume and exhausting unnecessary reactive gas using a vacuum exhaust system using a turbo molecular pump. The substrate or the material to be etched on the substrate is etched into submicron (1 μm or less) by causing plasma glow discharge in the reactive gas by applying high frequency or direct current energy while applying a bias between the substrate and the other electrode provided on the substrate. A vapor phase etching method characterized by performing anisotropic etching with a width or diameter of .