US20110042009A1

US20110042009A1 - Plasma etching device

Info

Publication number: US20110042009A1
Application number: US12/854,371
Authority: US
Inventors: Dongseok LEE; Hwankook CHAE; Heeseok MOON; Yunkwang CHOI
Original assignee: DMS Co Ltd
Current assignee: DMS Co Ltd
Priority date: 2009-08-18
Filing date: 2010-08-11
Publication date: 2011-02-24
Also published as: KR101091309B1; TW201108326A; KR20110018539A; CN101996842B; TWI401742B; CN101996842A

Abstract

A plasma etching device is provided. The device includes a chamber, a cathode assembly, and an integral cathode liner. The chamber provides a plasma reaction space. The cathode assembly is positioned at an inner and central part of the chamber and supports a substrate. The integral cathode liner has a plurality of first vents and second vents formed at two levels and spaced apart respectively such that the uniformity of a gas flow and exhaust flow within the chamber is maintained, and is outer inserted to the cathode assembly and coupled at its lower end part to an inner surface of the chamber.

Description

CROSS REFERENCE

This application claims foreign priority under Paris Convention and 35 U.S.C. §119 to Korean Patent Application No. 10-2009-0076043, filed Aug. 18, 2009 with the Korean Intellectual Property Office.

BACKGROUND OF THE INVENTION

1. Technical Field
The present invention relates to a plasma etching device for treating a large size wafer. More particularly, the present invention relates to a plasma etching device for improving plasma uniformity by outer inserting an integral cathode liner having a plurality of first vents and second vents formed at two levels respectively to be spaced apart, to a cathode assembly such that the uniformity of a gas flow and exhaust flow of a reaction gas within a chamber is maintained and simultaneously, preventing a flickering phenomenon by grounding a lower end part of the integral cathode liner to the chamber.
2. Description of the Related Art
Generally, a large size wafer used for a semiconductor integrated circuit device, a glass substrate that is a key part used for a Liquid Crystal Display (LCD), etc. are to form an ultra-minute structure of a desired form and form a circuit or thin film layer of a complex structure, by forming several thin film layers on a surface and selectively removing only part of the thin film layers. At this time, thin film manufacturing is carried out through many manufacturing processes such as a rinse process, a deposition process, a photolithography process, a plating process, an etching process, etc.
The above various treatment processes are mainly carried out within the chamber or reaction furnace capable of isolating a wafer or substrate from the external.
Among the above processes, particularly, the etching process is a process of removing desired materials from a wafer surface through a plasma chemical reaction by jetting a reaction gas (e.g., carbon tetrafluoride (CF₄), chlorine gas (Cl₂), hydrogen bromide (HBr), etc.) inside the chamber or reaction furnace. The etching process is a process of selectively removing a portion not covered with a photoresist using a photoresist pattern as a mask, and forming a minute circuit on the substrate.
Accordingly, because it is of most significance in the etching process to maintain etching uniformity for the whole substrate surface, plasma should be allowed to be uniformly formed within the chamber and get in contact with the whole substrate surface for the sake of improving the etching uniformity and preventing a process error.
In a conventional plasma etching device, in order to secure plasma uniformity within a chamber, a baffle plate is installed to have a plurality of vents formed in an outer circumference of a cathode assembly, a pumping exhaust part is installed below the chamber, and then, an exhaust pump is operated to pumping exhaust a by-product such as a reaction gas within the chamber, a polymer, a particle, etc. By doing so, the conventional plasma etching device secures the plasma uniformity through a uniform exhaust of the reaction gas within the chamber.
That is, the by-product such as the reaction gas, etc. is continuously uniformly discharged outside the chamber such that the plasma within the chamber uniformly diffuses on the substrate with no resistance of the reaction gas, the by-product, etc.
However, the conventional plasma etching device of the above structure has the following problems.
Firstly, because the reaction gas, the polymer, or the particle generated after plasma reaction is pump exhausted through one baffle plate, there is a limit in uniformly exhausting the reaction gas, the by-product, etc. Thus, there is a problem that it fails to secure the plasma uniformity within the chamber.
Secondly, because the baffle plate is not effectively grounded to the chamber, there is a problem that there occurs a plasma flickering phenomenon in which plasma between the vents is irregularly flickered.
Thirdly, because of the absence of a control means for controlling aperture ratios of the vents, there is a problem that it is impossible to minutely control an etching rate of the substrate through control of a gas flow or exhaust flow within the chamber.

SUMMARY OF THE INVENTION

An aspect of exemplary embodiments of the present invention is to address at least the problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of exemplary embodiments of the present invention is to maintain a uniformity of a gas flow and exhaust flow within a chamber to improve plasma uniformity, by pump exhausting a reaction gas, a polymer, or a particle generated after plasma reaction through an integral cathode liner having a plurality of first vents and second vents formed at two levels.
Another aspect of exemplary embodiments of the present invention is to improve a ground force of a cathode liner, thus preventing a plasma flickering phenomenon occurring between vents.
A further aspect of exemplary embodiments of the present invention is to secure an etching uniformity of the whole substrate surface by making it possible to control aperture rates of second vents and control plasma uniformity through a minute control of a gas flow and exhaust flow within the chamber.
According to one aspect of the present invention, a plasma etching device is provided. The device includes a chamber, a cathode assembly, and an integral cathode liner. The chamber provides a plasma reaction space. The cathode assembly is positioned at an inner and central part of the chamber and supports a substrate. The integral cathode liner has a plurality of first vents and second vents formed at two levels and spaced apart respectively such that the uniformity of a gas flow and exhaust flow within the chamber is maintained, and is outer inserted to the cathode assembly and coupled at its lower end part to an inner surface of the chamber.
The cathode liner includes a baffle plate having the first vents radially arranged, a liner part of a constant length coupled at its upper end to an inner circumference of the baffle plate, and an exhaust part provided in a lower end part of the liner part and coupled to the chamber, and having the second vents radially arranged.
The first vents of the baffle plate are comprised of slots spaced apart and arranged at regular intervals.
An inner circumference of the baffle plate is screw coupled at its several places to the upper end surface of the liner part.
The exhaust part includes an exhaust plate having the second vents through provided at a constant interval, the second vents being provided to be slope at a constant angle in an outside direction, and a coupling plate extending outside along an outer circumference of a lower end part of the exhaust plate and being screw coupled to the chamber.
A control plate sliding and rotating is provided on an upper surface of the exhaust plate, and the control plate has a plurality of control ports arranged and formed corresponding to the plurality of second vents to simultaneously control aperture ratios of the second vents.
A plurality of individual control plates are provided on the upper surface of the exhaust plate to be slidable on an upper part of the exhaust plate to control each of the aperture ratios of the plurality of second vents.
The device further includes a gasket for preventing a leakage of a reaction gas at a lower side surface of the coupling plate.
The cathode liner is coated with aluminum oxide (Al₂O₃), yttrium oxide (Y₂O₃).

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic side diagram illustrating a plasma etching device according to the present invention;

FIG. 2 is an exploded perspective diagram illustrating a cathode liner according to an exemplary embodiment of the present invention;

FIG. 3 is a perspective diagram illustrating a cathode liner according to an exemplary embodiment of the present invention; and

FIG. 4 is a partial exploded perspective diagram illustrating a cathode liner according to another exemplary embodiment of the present invention.

Throughout the drawings, the same drawing reference numerals will be understood to refer to the same elements, features and structures.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Exemplary embodiments of the present invention will now be described in detail with reference to the annexed drawings. In the following description, a detailed description of known functions and configurations incorporated herein has been omitted for conciseness.
A description of the present invention is made in detail with reference to the accompanying drawings.
FIG. 1 is a schematic side diagram illustrating a plasma etching device according to the present invention.
As illustrated in FIG. 1, the plasma etching device of the present invention includes a chamber 1, a cathode assembly 10, and a cathode liner 50.
The chamber 1 is to provide a plasma reaction space isolated from the external. A gas injector 5 jetting a reaction gas is installed at a top and center of the chamber 1. An exhaust port 8 is formed at a bottom and center of the chamber 1 to discharge a reaction by-product such as a reaction gas, a polymer, a particle, etc. to the external.
Also, the chamber 1 is grounded at its one side to the external to convert the reaction gas within the chamber 1 into a plasma state by a Radio Frequency (RF) power source 7.
The cathode assembly 10 is to form an electrode of the RF power source 7 and simultaneously, support a wafer or substrate (not shown) such that it can be positioned horizontally at a center within the chamber 1.
The cathode assembly 10 connects with the RF power source 7, and safely mounts the substrate on an upper surface thereof.
Thus, the RF power source 7 etching treats a substrate surface by plasma by electrically discharging the reaction gas jetted into the chamber 1 and converting the reaction gas into a plasma state.
The cathode assembly 10 can include an electrostatic chuck (not shown) for stably fixing the substrate and also, can install a gas pipe (not shown) for circulating helium (He) gas, etc. to cool the substrate.
The electrostatic chuck is a device for absorbing a target by an electrical attractive force operating between an electrode surface and the target.
The reaction gas is jetted inside the chamber 1 through the gas injector 5 formed on the same line as a center of the cathode assembly 10 in order for plasma to be uniformly formed on the substrate surface.
Thus, the reaction gas converts into a plasma state within the chamber 1 by the RF power source 7 and reacts with the substrate surface to selectively etch the substrate, and is discharged outside through an exhaust port 8 formed at a lower part of the chamber 1.
The cathode liner 50 is outer inserted to the cathode assembly 10 and installed. The cathode liner 50 is described in detail with reference to FIGS. 2 and 3.
FIG. 2 is an exploded perspective diagram illustrating the cathode liner 50 according to an exemplary embodiment of the present invention. FIG. 3 is a perspective diagram illustrating a combined state of the cathode liner 50.
The cathode liner 50 is an integral liner having a plurality of first vents 22 and second vents 42 formed at two levels respectively to be spaced apart such that a uniformity of a gas flow and exhaust flow within the chamber is maintained. The cathode liner 50 includes a baffle plate 20, a liner part 30, and an exhaust part 40.
The baffle plate 20 is to make a plasma reaction gas remain on the chamber 1 for a constant time and then discharge the plasma reaction gas. As illustrated, the baffle plate 20 is installed such that the baffle plate 20 is coupled to an upper end surface of the cylindrical liner part 30 and is positioned on an outer circumference surface of an upper end part of the cathode assembly 10.
Thus, an inner circumference surface of the baffle plate 20 is formed corresponding to an outer circumference surface of the cathode assembly 10. An outer circumference surface of the baffle plate 20 is formed corresponding to an inner circumference surface of the chamber 1. So, the baffle plate 20 is horizontally installed in a space part provided between the outer circumference surface of the cathode assembly 10 and the inner circumference surface of the chamber 1.
The baffle plate 20 is of a circular ring shape having a constant thickness. An insertion hole 25 is through provided at a center of the baffle plate 20 such that the cathode assembly 10 can be inserted into the insertion hole 25.
An outer circumference of the baffle plate 20 is not limited to a circular shape, and may be of a rectangular shape, etc. according to a shape of the inner circumference surface of the chamber 1.
Thus, the outer circumference surface of the baffle plate 20 is contact coupled along the inner circumference surface of the chamber 1, and an inner circumference surface of the insertion hole 25 is contact coupled along the outer circumference surface of the cathode assembly 10. So, a reaction space within the chamber 1 is partitioned into an upper part and a lower part.
The baffle plate 20 has a plurality of combination holes 20 b spaced apart and installed along a circumference of the insertion hole 25, and couples and fixes fixing bolts 20 a to an upper end surface of the liner part 30 using the combination holes 20 b.
First vents 22 are provided in the baffle plate 20.
The first vents 22, parts through which the reaction gas passes, are slots of constant lengths are radially spaced a distance apart and are arranged at regular intervals.
The first vents 22 are not limited to a slot shape, and may be formed in various shapes considering a plasma environment condition.
The liner part 30 is outer inserted to the cathode assembly 10, and has a cylindrical shape opened at its upper and lower parts.
The liner part 30 has an inner circumference surface formed and contacting corresponding to the outer circumference surface of the cathode assembly 10. Also, the liner part 30 has a plurality of combination holes 30 b provided in its upper end surface correspondingly to the combination holes 20 b provided in the baffle plate 20. So, the liner part 30 is coupled by the fixing bolt 20 a to contact with a lower side surface of the circumference of the insertion hole 25 of the baffle plate 20.
The exhaust part 40 is provided below the liner part 30.
The exhaust part 40 finally discharges the reaction gas, the by-product, etc. passing through the baffle plate 20 to the exhaust port 8 of the chamber 1. The exhaust part 40 includes an exhaust plate 41 extending from a lower end part of the liner part 30, and a coupling plate 45 extending outside from an outer circumference surface of a lower end part of the exhaust plate 41.
The exhaust plate 41 is formed to be slope at a constant angle outside from an outer circumference of the lower end part of the liner part 30. The second vents 42 are arranged at regular intervals.
The second vents 42 are not limited to a rectangular shape as illustrated, and may be through provided in various shapes such as a circular shape, a long-hole shape, etc.
The coupling plate 45 extends in a horizontal direction by a constant distance from the outer circumference of the lower end part of the exhaust plate 41. The coupling plate 45 has a plurality of combination holes 40 b through provided to combine with fixing bolts 40 a for the sake of fixation to the chamber 1.
Thus, by firmly combining the coupling plate 45 to the chamber 1 by the fixing bolts 40 a and increasing a ground force, the cathode liner 50 can prevent the plasma flickering phenomenon from occurring in the vents due to an unstable ground of a baffle plate as in a conventional plasma etching device.
A gasket 70 can be installed between the coupling plate 45 and the chamber 1 to prevent the unnecessary leakage of the reaction gas.
The gasket 70 may be a metal spring of a circular ring shape.
A control plate 60 can be further provided over the exhaust plate 41 correspondingly to the exhaust plate 41 for the sake of sliding rotation.
The control plate 60 is installed to be rotatably slid along the exhaust plate 41 in a state where the control plate 60 is outer inserted to the liner part 30 and is mounted on an upper surface of the exhaust plate 41. The control plate 60 is provided in a ring shape correspondingly to the exhaust plate 41.
The control plate 60 has control ports 62 through provided at regular intervals correspondingly to the second vents 42 of the exhaust plate 41.
Accordingly, as illustrated in FIG. 3, if the control plate 60 is rotated, an aperture ratio of each second vent 42 of the exhaust plate 41 can be simultaneously controlled according to an extent of overlapping with the control port 62.
That is, a worker rotates the control plate 60 at a suitable angle as indicated by arrow 63, thereby controlling the aperture ratio of the second vent 42 to the optimum condition and, at the time of pumping exhaust, minutely controlling a gas flow and exhaust flow within the chamber 1.
FIG. 4 illustrates a cathode liner 50 according to another exemplary embodiment of the present invention. Besides a construction of the control plate, this exemplary embodiment is identical with the above exemplary embodiment and thus, only a modified construction is described below.
As illustrated, a plurality of individual control plates 80 are installed on an upper surface of an exhaust plate 41.
The individual control plates 80 are installed corresponding to the number of second vents 42 of the exhaust plate 41 to control an aperture ratio of each second vent 42.
In detail, the individual control plates 80 are installed to slide along the exhaust plate 41 while opening and closing the second vents 42, respectively. By controlling each position of the individual control plate 80, a worker can differently control each of the aperture ratios of the second vents 42.
Guide members 82 and 83 may be installed at upper and lower ends of the exhaust plate 41 to provide a guide rail (i.e., a groove) for allowing upper and lower ends of the individual control plate 80 to be inserted and slid such that the individual control plate 80 can smoothly slide on an upper surface of the exhaust plate 41.
The guide members 82 and 83 may be installed by spacing apart band shape members from upper end and lower end surfaces of the exhaust plate 41, respectively, such that a groove for inserting an upper end and lower end of the individual control plate 80 is provided in state where the individual control plate 80 is arranged on an upper surface of the exhaust plate 41.
Thus, by moving a position of the individual control plate 80 and minutely controlling the aperture ratio of each second vent 42, a worker can more minutely control the uniformity of a gas flow and exhaust flow at the time of pumping exhausting a reaction gas, a by-product, etc. within the chamber 1.
The individual control plates 80 are not limited to a form illustrated in FIG. 4, and may be provided in a form of an open/close door capable of being slidably installed in the second vents 42 such as a common open/close door.
The cathode liner 50 can be coated with aluminum oxide (Al₂O₃), yttrium oxide (Y₂O₃), etc. of excellent corrosion resistance and abrasion resistance.
An operation process of the present invention is described below with reference to FIG. 1.
If a reaction gas is jetted into the chamber 1 from the gas injector 5 and the RF power source 7 is applied to the cathode assembly 10, the reaction gas induces discharge electricity and converts into a plasma state and then, etches a specific film of a substrate surface.
At this time, the reaction gas constantly and uniformly maintains a gas flow by the cathode liner 50 while sequentially passing through the first and second vents 22 and 42 together with a by-product, etc. as indicated by arrow 3. After that, the reaction gas is discharged to the exhaust port 8.
Here, the reaction gas passes through the first vents 22 and then is secondarily discharged out through the second vents 42. So, a space part formed between the baffle plate 20 and the exhaust part 40 performs a buffering role such that the gas flow and exhaust flow within the chamber 1 can be more uniformly maintained while being discharged.
Thus, by pumping exhausting a reaction gas, a polymer, or a particle generated after plasma reaction through the integral cathode liner 50 having the first vents 22 and the second vents 42, the present invention can improve a non-uniform discharge by means of a buffering effect of the space part operating between the baffle plate 20 and the exhaust part 40. In addition, the present invention can increase a ground force and prevent a plasma flickering phenomenon because the cathode liner 50 is extended and coupled to the chamber 1. Also, the present invention can control the aperture ratio of the second vent 42 to minutely control the plasma uniformity within the chamber 1.
For description convenience, the above exemplary embodiment is merely described as an example and thus, is not limited to the scope of claims and is all applicable to a plasma vacuum processing equipment such as a sputter or Chemical Vapor Deposition (CVD) as well.
As described above, the present invention has an effect of being capable of securing the uniformity of plasma on a substrate and securing the etching uniformity of the substrate by pumping exhausting a reaction gas through an integral cathode liner of a two-level structure, and minimizing a process error and improving a process efficiency by preventing a plasma flickering phenomenon capable of occurring between vents. The present invention has an effect of being capable of manufacturing a high quality substrate through the uniformity of an etching rate on the whole substrate surface by making it possible to minutely control plasma uniformity through aperture ratios of second vents.
While the invention has been shown and described with reference to a certain preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

What is claimed is:

1. A plasma etching device comprising:

a chamber for providing a plasma reaction space;

a cathode assembly positioned at an inner and central part of the chamber and supporting a substrate; and

an integral cathode liner having a plurality of first vents and second vents formed at two levels and spaced apart respectively such that the uniformity of a gas flow and exhaust flow within the chamber is maintained, and being outer inserted to the cathode assembly and coupled at its lower end part to an inner surface of the chamber.

2. The device of claim 1, wherein the cathode liner comprises:

a baffle plate having the first vents radially arranged;

a liner part of a constant length coupled at its upper end to an inner circumference of the baffle plate; and

an exhaust part provided in a lower end part of the liner part and coupled to the chamber, and having the second vents radially arranged.

3. The device of claim 2, wherein the first vents of the baffle plate are comprised of slots spaced apart and arranged at regular intervals.

4. The device of claim 3, wherein an inner circumference of the baffle plate is screw coupled at its several places to the upper end surface of the liner part.

5. The device of claim 2, wherein the exhaust part comprises:

an exhaust plate having the second vents through provided at a constant interval, the second vents being provided to be slope at a constant angle in an outside direction; and

a coupling plate extending outside along an outer circumference of a lower end part of the exhaust plate and being screw coupled to the chamber.

6. The device of claim 5, wherein a control plate sliding and rotating is provided on an upper surface of the exhaust plate, and the control plate has a plurality of control ports arranged and formed corresponding to the plurality of second vents to simultaneously control aperture ratios of the second vents.

7. The device of claim 5, wherein a plurality of individual control plates are provided on the upper surface of the exhaust plate to be slidable on an upper part of the exhaust plate to control each of the aperture ratios of the plurality of second vents.

8. The device of claim 5, further comprising a gasket for preventing a leakage of a reaction gas at a lower side surface of the coupling plate.

9. The device of claim 1, wherein the cathode liner is coated with aluminum oxide (Al₂O₃), yttrium oxide (Y₂O₃).