KR20060102042A - Neutral beam etching system having improved reflector - Google Patents

Abstract

The present invention provides an ion source for extracting an ion beam having a polarity, a grid assembly having a plurality of grid holes positioned at one end of the ion source and accelerating ion beams having a specific polarity, and a plurality of grid holes corresponding to the grid holes of the grid assembly. Reflector holes or slit portions formed therein, the reflector which reflects the ion beam passing through the grid hole in the reflector hole or slit portion and converts it into a neutral beam, and a substrate to be placed on the traveling path of the neutral beam. It can be done by including a stage.

In this case, the reflector, which plays an important role in the neutralization process, is made of glassy carbon, or the surface of the reflector hole or slit portion of the reflector is coated with glassy carbon or coated with diamond-like carbon (DLC). A neutral beam etching apparatus is provided.

Description

Neutral BEAM ETCHING SYSTEM HAVING IMPROVED REFLECTOR with Improved Reflector

1 is a side cross-sectional view schematically showing an improved neutral beam etching apparatus according to the present invention;

2 is a perspective view schematically showing a reflector according to an embodiment of the present invention;

3 is a schematic illustration of a neutral beam etching apparatus with an improved reflector in accordance with the present invention;

4 is a graph showing a comparison between etching states in the case of using a reflector according to the present invention and a conventional reflector.

<Description of the Reference Code>

10-ion beam source, 11-plasma generating chamber,

13-power supply, 20-grid assembly,

30-reflector, 31-reflector hole,

32-DLC coating film or glassy carbon coating film.

The present invention relates to a neutral beam etching apparatus having a reflector for generating an ion beam (or plasma) for etching or depositing a specific material layer on a substrate, and converting the ion beam into a neutral beam. And an improved reflector having an improved reflector such that upon reflection the surface of the reflector is not damaged by reaction with the ion beam.

In recent years, as the demand for high integration of semiconductor devices continues, design rules are further reduced in the design of semiconductor integrated circuits, and a critical dimension of 0.09 µm or less is required. Currently, equipment such as a reactive ion beam device (hereinafter referred to as an ion beam source) is used as a device for implementing such a nanometer-class semiconductor device. However, in such equipment, a large amount of ions exist for performing an etching process, and these ions collide with a semiconductor substrate or a specific material layer on the semiconductor substrate with energy of several hundred eV, so that physical and electrical Cause damage.

As an example of physical damage, the surface of a crystalline substrate or a particular material layer that collides with ions generated in an ion beam source may be converted to an amorphous layer, and only some components of the material layer where some of the incident ions are adsorbed or collided are selective. The chemical composition of the surface layer to be etched may change, and the atomic bonds of the surface layer may be broken by collision and become dangling bonds. These dangling bonds cause electrical damage as well as physical damage to the material. In addition, electric damage is caused by polysilicon notching due to charge up damage of the gate insulating film or charging of the photoresist. In addition to such physical and electrical damage, surface contamination may occur due to the contamination of the chamber material or the reaction gas when the CF-based reaction gas is used.

Therefore, in the nanometer-class semiconductor device, such physical and electrical damage caused by ions may lower the reliability of the device and further reduce the productivity, thereby increasing the integration of semiconductor devices and decreasing design rules. There is a demand for the development of a new concept of semiconductor etching apparatus and etching method that can be applied in response to this.

Among these, d. ratio. DB Oakes et al., "Selective, Anisotropic and Damage-Free SiO2 Etching with a Hyperthermal Atomic Beam," proposes an intact etching technique using an overheated atomic beam, Takashi Yunogami, Japan. ), Et al., "Development of neutral-beam-assisted etcher" (J. Vac. Sci. Technol. A 13 (3), May / June, 1995) using silicon with very little damage using neutral beams and neutral radicals. Oxide etching technology is proposed, M. MJ Goeckner et al., "Reduction of Residual Charge in Surface-Neutralization-Based Beams" (1997 2nd International Symposium on Plasma Process-Induced Damage.May 13-14, Monterey, CA.) Instead, an etching technique for chargeless superheated neutral beams is proposed.

D. B. The technique proposed by Mr. Ock et al. Has no electrical physical damage due to the absence of ions, and is considered to be low in contamination, but it is difficult to achieve large area, difficult to obtain anisotropy in ultrafine devices, and low etching speed. The technique proposed by Takashi Yunogami et al. Has the disadvantage that the area is easy to be enlarged, but the direction of the neutral beam is difficult to control, and the possibility of contamination during ion beam extraction is high. Also, M. second. While the technique proposed by Mr. Goeckner et al. Can achieve a large area and obtain a high neutral beam flux, the direction of the neutral beam due to the recombination of ions and electrons may not be clear and ions may be mixed. There is a big disadvantage.

On the other hand, the applicant of the present invention has disclosed a 'etching apparatus using a neutral beam' registered in the Republic of Korea Patent Registration No. 10-412953 on the basis of the technical content of the above documents, the application is an ion beam as a neutral beam Techniques for converting reflectors are described.

However, the surface of the reflector or the reflector hole is usually made of a metal such as a semiconductor, stainless steel, or silicon oxide (SiO 2), and the reflector surface is incident on such a surface, for example, as an ion beam introduced from the top enters, collides, and reflects. Damage (or etching) occurs.

Accordingly, since the amount of generated neutral beam flux is also reduced, there is a problem that the substrate to be processed cannot be easily etched.

Accordingly, the present invention has been made in view of the above problems, and is inexpensive and can contribute to a wide range of practical applications, and glassy carbon or diamond-like carbon (DLC) capable of hardness application, which is essential for other coating films, is possible. By applying the coating to the reflector, an etch apparatus having an improved reflector which prevents the surface of the reflector from being damaged by the ion beam flowing from the top, thereby increasing the neutral beam flux reaching the etched substrate. The purpose is to provide.

In order to achieve the above object, the present invention is an ion source for extracting an ion beam having a polarity, a grid assembly formed at one end of the ion source, a plurality of grid holes for accelerating the ion beam of a specific polarity, of the grid assembly A plurality of reflector holes or slit portions corresponding to grid holes are formed, and reflectors convert the ion beams passing through the grid holes in the reflector holes or slit portions into neutral beams, and on the traveling path of the neutral beams. It includes a stage for positioning the substrate to be etched, the reflector is made of glassy carbon, or the surface of the reflector hole or slit portion of the reflector is coated with glassy carbon or diamond-like carbon (DLC) It provides a neutral beam etching apparatus characterized in that.

According to such an apparatus, the ion beam incident on the reflector hole or slit portion does not easily react with the surface of the reflector hole or slit portion and is reflected without being absorbed by the reflector hole or slit portion surface, thereby protecting the reflector hole or slit portion. The substrate to be etched can be easily etched.

Further, according to the present invention, the incident angle of the ion beam incident on the surface of the reflector hole or the slit portion in the reflector can be in the range of 15 degrees or less.

Further, according to the present invention, the incident angle of the ion beam incident on the surface of the reflector hole or the slit portion in the reflector may be in the range of 5 ° to 15 °.

Further, according to the present invention, the reflection angle of the ion beam reflected from the surface of the reflector hole or the slit part in the reflector can be within a range of 40 degrees.

Preferably, the incident angle of the ion beam incident on the surface of the reflector hole or the slit portion in the reflector may be 5 °, and the reflection angle may be 10 °.

According to such incident angle and reflection angle conditions, etching of silicon oxide using SF6 gas proceeds effectively.

Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments, but can be modified and practiced in various forms by those skilled in the art within the scope of the appended claims. Accordingly, the following embodiments are to be understood as being provided to make the disclosure of the present invention more complete, and to more fully inform the person skilled in the art the scope of the present invention.

(Example)

First, as an etching apparatus to which an embodiment of the inventive concept may be applied, FIG. 1 schematically illustrates an inductively coupled radio frequency (RF) type ion beam source having a helical RF coil. On the other hand, Figure 1 is only intended to explain in more detail the illustration and description of the present invention, the present invention is not limited to the ion beam source of Figure 1 various ways, such as capacitively coupled RF type ion beam source, helicon wave It is, of course, applicable to both the combined ion beam source, the anion source or the electron-cyclotron reactor (ECR) ion beam source.

Referring to FIG. 1, the inductively coupled RF ion beam source 10 is configured with a plasma generating chamber 11, typically made of quartz. In addition, the ceiling of the plasma generation chamber 11 is provided with a gas supply port 19 for supplying a reaction gas such as F series or Cl series and O2 gas for cleaning, and an outer wall of the plasma generation chamber 11. Induction coil 14 is wound around, the induction coil 14 is connected to the RF matching box 12, the RF matching box 12 is connected to the RF power supply 13 that can supply RF power. In this case, the RF power supply 13 generates a high frequency of 13.56 MHz of a high voltage, in order to generate a plasma.

In addition, the lower end of the plasma generating chamber 11 is provided with a multi-layered grid assembly 20 having grid holes 21a and 22a through which ion beams can pass, for example, an upper grid 21 and a lower grid 22. This limits the extraction of ions from the plasma generating chamber 11. Here, an ion beam path is formed by the grid holes 21a and 22a.

On the other hand, the grid assembly 20 is located between the lower grid 22 and the upper grid 21, and the upper grid 21 and the lower grid 22 to which a positive voltage is applied to the grid hole 21a, It may consist of a grid assembly consisting of an insulating layer with holes in communication with 22a).

In addition, the grid assembly includes a first grid of the upper side to which a positive voltage is applied, a second grounded middle grid, a third grid of the lower side to which the same positive voltage as the first grid is applied, and a first grid. It may be composed of a first insulating layer between the second grid, and a second insulating layer between the second grid and the third grid. The construction of such a grid assembly is described in detail in Korean Patent Application No. 10-2004-0014977 "Medium Sum Beam Source for Etching Semiconductor Using Triple Grid".

Here, the upper and lower grids (21, 22) is usually made of a material of metal and graphite (graphite), a metal in the case of using a non-corrosive gas, a grid of graphite material in the case of using a corrosive gas As the insulating layer, an oxide having a dielectric constant of about 3 to 5, a nitrite having a dielectric constant of about 6 to 9, or a ferroelectric material having a dielectric constant of several tens or a single mixture are used.

In addition, the lower end of the grid assembly 20, as shown in Figure 2 is configured to be in close contact with the reflector 30 to reflect the incident ion beam to convert to a neutral beam.

The material of the reflector 30 may be made entirely of a semiconductor such as silicon, a metal such as silicon oxide or stainless steel, and only the surface of the reflector hole 31 formed in the reflector may be made of these materials.

In particular, in the present invention, the reflector 30 is formed of glassy carbon, only the surface of the reflector hole 31 is composed of glassy carbon, or diamond like carbon (DLC). It is composed by coating with material.

2 shows a reflector 30 in which a hole 31 of a reflector is coated with a DLC film or a glassy carbon film 32 to form a hole 31. Meanwhile, in FIG. 2, although the reflector hole 31 is illustrated in a cylindrical shape, the reflector hole 31 may be formed in various forms such as a rectangular or polygonal pillar shape without being limited thereto. In particular, when the inventors implement the actual etching apparatus, the slits may be formed inside the reflector instead of the reflector hole 31 as described in Patent Application No. 2003-0042116 (03.06.26). In the present specification, both the reflector hole and the slit portion are collectively described as the term "reflector hole".

According to an embodiment, the formation of the holes 31 and the slits in which the DLC coating layer 32 is formed may be performed by washing the holes 31 or the slits of the reflector 30 with a cleaning liquid to remove the natural oxide layer, and the holes 31. Alternatively, the metal layer and the Si-based layer may be deposited on the surface of the slit portion, the layer may be stabilized by using hydrogen gas, and the DLC thin film 32 may be deposited by using hydrogen gas and methane gas.

Here, the washing of the reflector 30 is washed for 10 minutes each in an ultrasonic cleaner using TCE (trichloroethylene), acetone (acetone), methanol (methaol), distilled water (DI water), the removal of the natural oxide film with HF solution Is done.

Here, the conventional deposition of the metal layer on the hole 31 is to facilitate the deposition of the DLC coating film 32 on the surface of the hole 31, for example, using a metal such as Cr, Ni, Ti, etc. It can be deposited using DC Magnetron Sputtering.

On the other hand, the DLC coating layer 32 may be deposited to a predetermined thickness using PECVD (Plasma Enhanced Chemical Vapor Deposition).

In addition, in the method of coating the holes 31 and the slit portion of the reflector with the glassy carbon film 32 according to an embodiment, first, a resin of a furan-based material or an imide-based material is applied to the reflector holes 31 or the slit portion. The polymerization is carried out by curing the mixture at a temperature of less than 100 ° C. for several tens of hours, followed by heat drying at a high temperature of 1200 ° C. or higher.

On the other hand, in the reflector 30 formed with the glass 31 or the diamond-like carbon (DLC) -coated hole 31 or the slit portion, an RF or DC high voltage power supply for plasmalizing the cleaning gas only within the reflector ( 33: see FIG. 1).

Referring to FIG. 3, a plurality of grid holes 21a and 22a having a constant diameter of the grid assembly 20 positioned at the rear end of the ion source 10 along the path of the ion beams generated from the ion source 10 may be used. After passing through the glass-like carbon film or diamond-like carbon (DLC) film 32 formed in the reflector 30 is reflected on the surface of the reflector hole 31 or the slit portion is converted to a neutral beam, the substrate 40 to be etched The incident state of the specific material layer on the substrate 40 to be etched is shown.

On the other hand, it is preferable that the diameter of the reflector holes 31 is the same or larger than the diameter of the grid holes (21a, 22a). Meanwhile, the reflector 30 may have a protrusion formed at the front end thereof so that the reflector 30 may be interpolated in the protrusion formed along the edge at the rear end of the grid assembly 20. However, the coupling relationship between the grid assembly 20 and the reflector 14 is not limited to this, and vice versa, that is, the grid assembly 20 can be configured to be interpolated into the reflector 30, and generally known fasteners It can be configured in various ways.

Preferably, the grid holes 21a and 22a and the reflector holes 31 are arranged at equal intervals in concentric circles.

Meanwhile, the reflector hole 31 or the slit portion is inclined at a predetermined angle with respect to the straight direction of the ion beam so that the ion beam passing through the grid holes 21a and 22a is reflected by the reflector hole 31 and the slit portion. Specifically, the reflector hole 31 or the slit portion may be configured to be inclined at a predetermined angle θt with respect to the center line of the cylindrical reflector 30 in the reflector 30. Alternatively, the reflector hole 31 or the slit portion may be formed in the reflector 30 in parallel with the center line of the reflector 30.

The reflector 30 is not necessarily limited to a circular shape and may be manufactured in various shapes, for example, a polygonal shape such as a square.

On the other hand, the inclination of the reflector hole 31 or the slit portion is formed such that the ion beam that goes straight after passing through the grid holes 21a and 22a is reflected only once in the reflector hole 31. In this embodiment, the inclination of the reflector hole 31 or the slit portion is configured such that the incident angle θ i of the ion beam incident on the inner surface of the reflector hole 31 is within at least 15 °. Preferably, it is configured to be in the range of 5 ° to 15 °. The incidence angle θ i of the ion beam ranges from at least 5 ° to 15 °, meaning that the incidence angle based on a normal normal to the surface of the reflector hole 31 is at least 75 ° to 85 °.

In addition, the reflection angle θr of the neutral beam reflected from the surface of the reflector hole 31 in the reflector 30 is configured to be within a range of 40 °.

On the other hand, the etched substrate 40 is disposed on the traveling path of the neutral beam reflected and converted from the reflector 30. The etched substrate 40 is mounted on a stage (not shown) in the reaction chamber maintained at a constant vacuum degree, and may be disposed in a vertical direction with respect to the traveling path of the neutral beam, and according to the type of etching process. and its position and direction are controlled so that it can be tilted at θ). Preferably, the etching layer of the etched substrate 40 is made of silicon or silicon oxide.

On the other hand, in applying the etching process of the present invention, the reaction gas is not limited to a specific gas, and can be used in various ways depending on the type of the etching target material layer and the type of etching mask layer. For example, in the case of etching silicon, a silicon oxide film may be used as an etching mask, and as the reaction gas, Cl ₂ , Cl ₂ / C ₂ F ₆ , SiCl ₄ , CCl ₄ / O ₂ , SiCl ₄ / O ₂ , Gas combinations such as SF ₆ can be selected and used in various ways.In the case of etching Al, a silicon oxide film, a silicon nitride film, or a photoresist film is used as an etching mask and Cl ₂ / SiCl ₄ , Cl ₂ / CCl ₄ , Cl ₂ / CHCl ₃ , Cl ₂ / BCl ₃ and the like can be used in various ways depending on the use of course.

4 is a reflector having a reflector hole 31 according to the present invention deposited with a DLC 32 and a hole of a reflector of the prior art coated by depositing silicon (Si), silicon oxide (SiO 2), or other metal layer ( 30 is a graph showing etching characteristics when the SiO 2 layer on the etched substrate 40 is etched by using the ion beam apparatus having the same. SF ₆ was used as an etching gas, the incident angle was 5 °, and the RF power was 300W and the acceleration voltage was 400V.

According to Fig. 4, when the incident angle θ i is 5 °, in the case of using the reflector provided with the hole 31 in which the other DLC coating 32 is formed in the present invention, the reflection angle θ r of 0 ° to 40 ° is conventionally used. The etching rate is higher than that of the reflector provided with the reflector hole according to the technology. Particularly, in the present invention having the DLC film 32 having a reflection angle of about 10 °, the etching depth of 600 µs or more is shown, and the etching depth of 200 to 500 µs is shown in the prior art having the coating layer.

As described above, according to the present invention, the reflector is made of glassy carbon or diamond-like carbon (DLC) coating, which is inexpensive and can contribute to a wide range of practical applications, and which is capable of applying hardness, which is an essential part of other coating films. By applying to, it is possible to prevent the phenomenon that the surface of the reflector is damaged by the ion beam flowing from the top,

Accordingly, since the neutral beam flux reaching the etched substrate is increased, the etched substrate can be etched under a large amount of neutral beam flux.

Claims (13)

Ion source for extracting an ion beam having polarity, A grid assembly positioned at one end of the ion source and having a plurality of grid holes for accelerating ion beams of a specific polarity; A plurality of reflector holes or slit portions corresponding to the grid holes of the grid assembly are formed, and includes a reflector for converting the ion beams passing through the grid holes in the reflector holes or slit portions into a neutral beam. , And a surface of the reflector hole or the slit portion of the reflector is coated with diamond-like carbon (hereinafter referred to as DLC). Ion source for extracting an ion beam having polarity, A grid assembly positioned at one end of the ion source and having a plurality of grid holes for accelerating ion beams of a specific polarity; A plurality of reflector holes or slit portions corresponding to the grid holes of the grid assembly are formed, and includes a reflector for converting the ion beams passing through the grid holes in the reflector holes or slit portions into a neutral beam. , And the reflector is made of glassy carbon, or the surface of the reflector hole or slit portion of the reflector is made of glassy carbon.  The neutral beam etching apparatus of claim 1 or 2, wherein a diameter of the reflector hole or the slit portions is equal to or larger than that of the grid hole. The reflector hole or the slit portions are inclined at an angle with respect to the straight direction of the ion beam so that the ion beam straight through the grid holes is reflected in the reflector hole or slit portion. Neutral beam etching device.  The neutral beam etching apparatus according to claim 1 or 2, wherein the reflector holes or slits are inclined at a predetermined angle with respect to the center line of the reflector in the reflector. The method according to claim 1 or 2, wherein the ion source is a capacitively coupled RF type ion beam source, a helicon wave coupled ion beam source, an anion source, an electron-cyclotron reactor (ECR) ion beam source, Neutral beam etching apparatus, characterized in that any one of the inductively coupled plasma source. The neutral beam etching apparatus according to claim 1 or 2, wherein the ion source is an inductively coupled plasma source. The neutral beam etching apparatus of claim 1 or 2, wherein the reflector hole or the slit portion is formed in a cylindrical shape or a rectangular pillar shape.  The neutral beam etching apparatus according to claim 1 or 2, wherein an incident angle of the ion beam incident on the surface of the reflector hole or the slit portion in the reflector is within 15 degrees.   The neutral beam etching apparatus according to claim 1 or 2, wherein a reflection angle of the ion beam reflected from the surface of the reflector hole or the slit portion in the reflector is within 40 degrees.    The neutral beam etching apparatus of claim 1, wherein an incident angle of the ion beam incident on the surface of the reflector hole or the slit part in the reflector is 5 °, and the reflection angle is 10 °. 3. The neutral beam etching apparatus according to claim 1 or 2, further comprising a stage for positioning an etched substrate on a traveling path of the neutral beam. The neutral beam etching apparatus of claim 11, wherein the etching layer on the substrate is formed of silicon or silicon oxide.

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