KR19980084815A - Chemical Aid Ion Beam Etcher - Google Patents

Abstract

The present invention relates to a chemically assisted ion beam etching apparatus used to etch a semiconductor, comprising a substrate holder on which a vacuum chamber and an etching target substrate are mounted, an ion gun irradiating an accelerated ion beam to the substrate, and an etching target portion of the substrate. A plurality of gas injection holes for injecting a reactive gas to induce a chemical reaction with the substance is provided around the mounting portion on which the substrate of the substrate holder is mounted, and a discharge pipe for discharging the reactive gas is formed in the center of the mounting portion. A liquid nitrogen trap containing liquid nitrogen in a ring-shaped tube is provided as an adsorption means for removing a reactive gas and a gas which does not contribute to etching. Therefore, most ion beams having a low collision frequency with the reactive gas contribute to the etching by impinging on the substrate to be etched while changing the path of progress, and the reactive gas is locally maintained only around the substrate. As the secondary etching is performed by the chemical reaction of the etching, the etching proceeds accurately in the desired vertical direction, and the time required for etching is also shortened, thereby increasing efficiency.

Description

Chemical Aided Ion Beam Etchers

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemically assisted ion beam etching apparatus. In particular, chemically assisted ion beams are distributed around the substrate to be etched to reduce the frequency of collision with the ion beam accelerated toward the etching target. The present invention relates to an ion beam etching apparatus.

Chemical assisted ion beam etching (CAIBE), which is one of the dry etching devices, is called CAIBE (Chemical Assisted Ion Beam Etching) device, which accelerates the focused ion beam by high voltage and enters the substrate to be etched and forms an etching target area. By irradiating a reactive gas that causes a chemical reaction with the ion beam separately around the substrate to be etched, the collision of the ion beam and the chemical reaction by the reactive gas proceed simultaneously, thereby anisotropically etching the etched portion of the etching target plate in a predetermined depth.

1 is a view schematically showing the configuration of a conventional chemically assisted ion beam etching apparatus.

In this regard, the chemically assisted ion beam etching apparatus includes a substrate holder 3 on which an etching target substrate 4 is mounted, an ion gun 1 for irradiating an ion beam to the substrate, and an etching target portion of the substrate 4. A reactive gas feeder 2 is provided which supplies a reactive gas which induces a chemical reaction with the substance. Reference numeral 2a denotes a part of the reactive gas feeder, which ejects the injected gas by forming fine holes at predetermined intervals on the surface thereof.

In the conventional chemically assisted ion beam etching apparatus, when the injection ring 2a is positioned within a radius of a traveling cross section of the ion beam accelerated from the ion gun, the surface of the injection ring 2a is etched by the accelerated ion beam, and the etched material In order to contaminate the surface of the board | substrate 4, the injection ring 2a was arrange | positioned so that it may not overlap in the cross section of an ion beam. The reactive gas emitted from the injection ring 2a disposed in the region deviating from the accelerated path of the ion beam thus accelerated is not concentrated and distributed only on the surface of the substrate, but diffuses during the injection process and spreads into the chamber. In particular, when the substrate 4 is to be rotated at a constant speed while being maintained at a constant angle with respect to the incident ion beam, the size and arrangement position of the injection ring 2a are severely restricted, and thus, between the substrate 4 and the injection ring 2a. The spacing of must be further spaced apart, increasing the pressure in the vacuum chamber due to the diffusion of the reactive gas.

As described above, as shown in FIG. 2, the probability of collision with the ion beam is increased. Accordingly, the ion beam consumes kinetic energy due to the collision of the ion beam and the reactive gas, and the reactive gas is ionized by the collision, thereby making it impossible to contribute to the chemical reaction, thereby rapidly decreasing the etching progression efficiency. In addition, since the path of the ion beam is changed by collision with the reactive gas, the direction of the ion beam is distorted and the straightness is weakened, so that anisotropic vertical etching is not properly performed.

SUMMARY OF THE INVENTION The present invention has been made to improve the above problems, and provides a chemically assisted ion beam etching apparatus that increases the etching speed and precision by controlling the reactive gas to be distributed mainly around the substrate to lower the collision frequency with the ion beam. The purpose is.

1 is a view schematically showing a conventional chemically assisted ion beam etching apparatus,

FIG. 2 is a view for explaining an etching progress state during etching through the chemically assisted ion beam etching apparatus of FIG. 1;

3 is a view schematically showing a chemically assisted ion beam etching apparatus according to an embodiment of the present invention,

FIG. 4 is a view for explaining an etching progress state during etching through the chemically assisted ion beam etching apparatus of FIG. 3.

Explanation of symbols for main parts of the drawings

1, 11: ion gun 2: reactive gas feeder

3, 13: substrate holder 4, 14: substrate

13a: mounting portion 13b: gas nozzle

13c: vent 15: liquid nitrogen trap

In order to achieve the above object, the chemically assisted ion beam etching apparatus according to the present invention includes a vacuum chamber, an ejector for discharging air inside the vacuum chamber, a substrate holder on which an etching target substrate is mounted, and an ion beam irradiating the etching target substrate. In a chemically assisted ion beam etching apparatus having a gun and a reactive gas supply for supplying a reactive gas for inducing a chemical reaction with a material forming an etch target portion of the substrate in the chamber, wherein the substrate on the substrate holder; Adsorption means for adsorbing the reactive gas or the gas produced by the reaction that did not contribute to the chemical reaction with the is characterized in that it is further provided.

The adsorption means preferably comprises a ring-shaped tube and the liquid nitrogen contained in the tube. The substrate holder includes a plurality of gas injection holes through which the reactive gas from the reactive gas supplier is ejected at a predetermined position around the mounting portion on which the substrate is mounted, and the reactive gas injected from the gas injection holes passes through the etching target substrate. It is preferable that an exhaust port exhausted by a pump separate from the discharger is provided at a central predetermined portion of the mounting portion so as to guide the flow.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a view schematically showing a chemically assisted ion beam etching apparatus according to an embodiment of the present invention.

Referring to this, in the chemically assisted ion beam etching apparatus, the substrate 14 is mounted inside the vacuum chamber, and the substrate holder 13 and the substrate holder 13 are provided with a plurality of gas injection holes 13b through which reactive gas is injected at one side thereof. An ion gun (11) provided at a position opposite to and a liquid nitrogen trap (15) made of a ring tube containing liquid nitrogen as adsorption means for adsorbing gas are provided.

The ion gun 11 is a device for shooting an accelerated ion beam on a target, and is configured to focus and accelerate ions generated by an ion reaction chamber for generating ions and a plurality of grids for applying an electric field.

The substrate holder 13 is provided with a plurality of gas injection ports 13b and exhaust ports 13c in addition to the main function of mounting the substrate to control the reactive gas flow to the substrate. In this case, the exhaust port is provided to discharge the reactive gas in addition to providing the inside of the chamber in a vacuum state.

The gas injection port 13b provided in the substrate holder 13 is connected to a reactive gas injector (not shown) through an appropriate pipe. The amount of reactive gas injected into the chamber through the gas injection port 13b is controlled by a mass flow controller provided in the reactive gas injector. The gas injection port 13b is connected to the substrate 14 so that the reactive gas ejected from the gas injection port 13b can easily reach the surface of the substrate 14 with respect to the mounting portion 13a on which the substrate 14 of the substrate holder 13 is mounted. It is preferable that the center thereof is provided above a predetermined height with respect to the bottom surface of the mounting portion 13a on which is mounted. In the example shown, the gas injection port 13b is located in the inclined surface 13d inclined with respect to the mounting surface on which the board | substrate 14 is mounted, and the gas injection port 13b and the board | substrate 14 oppose mutually.

And the exhaust port 13c is provided in the center of the mounting part 13a in which the board | substrate 14 is mounted so that the reactive gas blown out from the gas injection port 13b may be discharged immediately after passing through the board | substrate 14 surface. The exhaust port 13c is for exhausting lower than the average vacuum degree in the chamber by another pump separate from the pump for the ejector installed to maintain the chamber in vacuum.

Therefore, the reactive gas is mostly maintained through a path connecting the respective gas injection ports 13b and the exhaust ports 13c in the vacuum chamber, thereby restricting the diffusion of the reactive gas and lowering the collision frequency with the accelerated ion beam.

Also, a ring-shaped tube is provided between the substrate holder 13 and the ion gun 11 as adsorption means for removing the gas generated after the chemical reaction between the reactive gas diffused in another direction and not directed to the exhaust port 13c. The liquid nitrogen trap 15 in which liquid nitrogen is contained is provided. The liquid nitrogen trap 15 is preferably formed to have an inner diameter larger than the beam cross-sectional area of the ion beam so that the liquid nitrogen trap 15 is provided at a position outside the traveling path of the ion beam. In addition, the liquid nitrogen trap 15 is possible in various shapes to increase the surface area in addition to the ring shape to increase the adsorption efficiency. The liquid nitrogen is preferably maintained at an appropriate temperature that does not interfere with the adsorption efficiency of the gas to be removed and the flow of the ion beam in the chamber. In this example, the temperature of liquid nitrogen was also maintained at 77K.

The etching process of the chemically assisted ion beam etching apparatus structured as described above will be described with reference to FIG. 4 for explaining the etching progress state during etching through the chemically assisted ion beam etching apparatus of FIG. 3.

The substrate to be etched is mounted on the substrate holder 13, and the inside of the vacuum chamber is maintained at a predetermined pressure state. Next, while injecting the reactive gas through the gas injection port 13b provided in the substrate holder 13 from the reactive gas supplier, the ion beam 11 is accelerated to the target region of the substrate to be etched. At this time, when the flow of the reactive gas is induced through the exhaust port 13c provided in the center of the substrate holder 13 by the operation of the pump, the substrate 14 is etched by the collision of the accelerated ion beam and the chemical reaction of the reactive gas. The etching proceeds in the desired pattern. At this time, most of the reactive gas exiting the gas injection port 13b flows toward the exhaust port 13c, and comes into contact with the substrate 14 before entering the exhaust port 13c to assist etching by chemical reaction, and then continue to flow. Therefore, it exits through the exhaust port 13c. In addition, the reactive gas diffused to the upper portion of the reactive gas exiting the gas injection port 13b is adsorbed by the liquid nitrogen trap 15 to block the progress of the ion beam on the path of travel.

Therefore, the ion beam impinges on the substrate to be etched 14 without changing its propagation path vertically, thereby contributing to etching, and the reactive gas reacts chemically with the substrate 14 while maintaining its flow locally only around the substrate 14. By the secondary etching is performed by the etching is precisely progressed in the desired vertical direction, the time required for etching is also shortened to increase the efficiency. As described above, according to the improvement of precision and the speed of etching processing, the area of the etching target that can be processed in one etching target process is increased, and the process of simultaneously mounting and processing several substrates at the same time enables the production efficiency to be improved.

As described above, in the chemically assisted ion beam etching apparatus according to the present invention, the localized flow of the reactive gas is induced only around the substrate, so that the collision rate with the ion beam is low, the etching speed is improved, and the etching precision is increased.

Claims (5)

A chemical reaction with a vacuum chamber, an ejector for discharging air in the vacuum chamber, a substrate holder on which an etching target substrate is mounted, an ion gun irradiating an ion beam to the etching target substrate, and a material forming an etching target portion of the substrate In the chemically assisted ion beam etching apparatus having a reactive gas supply for supplying a reactive gas to the inside of the chamber, And an adsorption means for adsorbing a reactive gas or a gas generated by the reaction, which is not contributing to the chemical reaction with the substrate, above the substrate holder. The chemical assisted ion beam etching apparatus of claim 1, wherein the adsorption means comprises a ring-shaped tube and liquid nitrogen contained in the tube. The chemically assisted ion beam etching apparatus according to claim 1, wherein a plurality of gas injection holes for ejecting the reactive gas from the reactive gas supplier are provided at a predetermined position around a mounting portion of the substrate holder. According to claim 3, wherein the exhaust gas is discharged by a separate pump from the discharger is provided in the central predetermined portion of the mounting portion so that the reactive gas injected from the gas injection port is guided to flow through the substrate to be etched. Chemical auxiliary ion beam etching apparatus. The chemical assisted ion beam etching apparatus of claim 3, wherein the gas injection hole is provided above a predetermined height with respect to a bottom surface of the mounting part.