KR20070075603A - Plasma etching apparatus having o-ring seal structure - Google Patents

Abstract

A plasma etching apparatus with an O-ring seal structure is provided to prevent a bottom Vpp drop and a bottom reflect power loss in applying RF by controlling an arcing phenomenon frequently occurring in a conventional bellows seal structure. An upper electrode(16) is formed in the upper region of a process chamber(12). A lower electrode(24) on which a wafer is placed is formed in the lower region of the process chamber. The wafer is elevated by a wafer elevating pin(30), penetrating the lower electrode. A shaft(34) is installed to penetrate the process chamber, elevating the wafer elevating pin. An O-ring seal structure is installed in the process chamber to surround the shaft, maintaining the airtightness in the process chamber and composed of a stator(110), a first O-ring(120) and a second O-ring(122). The stator has a corner part of a round shape. The first O-ring is inserted into the stator to come in contact with the shaft. The second O-ring is interposed between the stator and the process chamber. The stator can be of a cylindrical type whose upper region is a dome shape, made of a ceramic material.

Description

Plasma etching apparatus having O-ring seal structure

1 is a cross-sectional view schematically showing a plasma etching apparatus having an O-ring seal structure according to the present invention.

** Description of the symbols for the main parts of the drawings **

12: process chamber

16: upper electrode

24: lower electrode

30: wafer lift pin

32: wafer lift pin support

34: shaft

36 drive unit

100: O-ring seal structure

110: Stator

120: the first O-ring

122: the second O-ring

The present invention relates to a plasma etching apparatus, and more particularly, to a plasma etching apparatus having an O-ring seal structure for preventing leakage of airtightness that may be generated due to a shaft for elevating a wafer lift pin through a process chamber. .

Recently, with the development of information communication technology and the rapid spread of personal computers and information communication equipment, semiconductor devices are required to have high processing speed, large storage capacity, and high stability. Accordingly, the manufacturing technology of semiconductor devices has been developed to improve the degree of integration, reliability, and response speed.

Generally, a semiconductor device is manufactured by selectively and repeatedly performing a process such as photographing, ion diffusion, etching, and deposition on a wafer, which is a semiconductor substrate.

The etching process is one of the methods of removing the thin film deposited on the wafer surface in the manufacturing technology of the semiconductor device. Conventional chemicals used in the past are called liquid etching because they use liquid chemicals. Plasma etching, ion etching and sputter etching that do not use chemicals are collectively called dry etching. . Plasma etching is a method of chemically reacting a chemically active gas plasma (usually a fluorine compound) with a sample surface.

A plasma etching apparatus for performing such plasma etching includes an upper electrode and a lower electrode spaced at a predetermined distance in parallel to each other in a process chamber having a predetermined space, and a predetermined reaction gas is injected between the upper electrode and the lower electrode. It forms an electric field in the state to convert the reaction gas into a plasma state to etch a thin film deposited on the wafer surface. Such plasma etching apparatuses are frequently used because of the high degree of integration of semiconductor products, because the plasma etching apparatus enables highly precise etching.

On the other hand, in order to implement a very precise etching using the plasma etching apparatus, the distance between the upper electrode and the lower electrode provided in the process chamber during the process must be maintained at a predetermined predetermined distance. Then, the wafer is lifted by the wafer lift pins for loading at the start of the process and unloading at the completion of the process between the two electrodes held at regular intervals.

In the conventional plasma etching apparatus, the upper electrode is installed in the upper region of the process chamber, and the lower electrode is provided at a position spaced downward from the upper electrode by a predetermined interval. When the wafer is brought into the process chamber by the robot arm and placed on the wafer lift pin that has been raised to a predetermined height, the shaft connecting the wafer lift pin and the drive unit is lowered to lower the wafer to the lower electrode. When the reaction gas is filled in the process chamber through the gas supply pipe, a predetermined RF (Radio Frequency) power is applied to the upper electrode, a bias power is applied to the lower electrode, and an electric field is formed between the upper electrode and the lower electrode, thereby reacting the gas into the plasma. Is switched. After etching of the wafer by plasma, the wafer lift pin is raised to a predetermined height by the shaft, and the wafer lifted by the wafer lift pin is carried out of the process chamber by the robot arm.

Since the shaft for moving the wafer lift pin up and down is installed through the process chamber, airtight leakage may occur through the shaft through portion of the process chamber. Therefore, bellows are installed around the shaft to block air inflow and out of the process chamber. At this time, the bellows is a member that is stretchable up and down by a predetermined length, the lower end is fixed to the bottom of the process chamber, the upper end is fixed to the wafer lift pin support. Therefore, the bellows expands or contracts by a predetermined length as the wafer lift pin moves up and down while sealing the inside of the process chamber from the outside.

By the way, the bellows is exposed to the plasma during the process, in particular, there is a problem that arcing occurs in the wrinkles of the bellows. Such arcing can lead to a decrease in bottom peak voltage and increase in low reflect power loss when RF is applied, a wafer breakage, and shaft damage. As a result, there arises a problem that productivity is lowered due to an increase in the occasional PM (Preventive Maintenance).

The present invention has been made to overcome the problems of the prior art, the technical problem to be achieved by the present invention is to prevent the leakage of airtight that can be generated due to the shaft to lift the wafer lift pin through the process chamber and In addition, to provide a plasma etching apparatus having an O-ring seal structure that can prevent the occurrence of arcing.

Plasma etching apparatus having an O-ring seal structure according to the present invention for achieving the above technical problem is a process chamber, an upper electrode provided in the upper region of the process chamber, a lower electrode provided in the lower region of the process chamber and the wafer And a wafer lift pin installed to penetrate the lower electrode to elevate the wafer, a shaft installed to penetrate the process chamber to elevate the wafer lift pin, and a process chamber to surround the shaft to maintain airtightness inside the process chamber. An o-ring seal structure, wherein the o-ring seal structure is installed in the process chamber to surround the shaft, the stator having a rounded corner portion, a first O-ring inserted into the stator to be in contact with the shaft, and the stator and the process chamber. It consists of a 2nd O-ring interposed between.

Preferably, the stator may be cylindrical having an upper region of which has a dome shape.

Preferably, the stator may be a ceramic material.

Preferably, the material of the O-rings may be made of chromium stainless or titanium.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed subject matter is thorough and complete, and that the scope of the invention to those skilled in the art will fully convey. Like numbers refer to like elements throughout.

1 is a cross-sectional view of a plasma etching apparatus having an O-ring seal structure according to a preferred embodiment of the present invention.

Referring to FIG. 1, the plasma etching apparatus 10 according to the present invention includes a sealed process chamber 12 in which a predetermined vacuum atmosphere is formed by a vacuum pump (not shown). One side of the process chamber 12 is provided with a wafer inlet and outlet 14 for inflow and outflow of the wafer W to be processed, and a gas outlet 22 for discharging gas upon completion of the process at the lower side of the process chamber 12. Is prepared.

An upper electrode 16 and a lower electrode 24 are provided in the upper region and the lower region of the process chamber 12 to be spaced apart at predetermined intervals, respectively. The upper electrode 16 serves as a shower head for evenly distributing the reaction gas in the process chamber 12 when supplying the reaction gas, and receives an RF power to generate an electric field between the lower electrode 24. It also forms a role of converting the reaction gas into plasma. A cooling plate 18 for controlling the temperature of the upper electrode 16 and a gas supply pipe 20 for supplying a reaction gas to the upper electrode 16 are installed above the upper electrode 16. do.

The wafer W, which is a process object, is seated on the lower electrode 24 provided in the lower region of the process chamber 12, and serves to convert the reaction gas into plasma together with the upper electrode 16 as described above. The lower electrode 24 is supported by the lower electrode support 28.

The wafer lift pins 30 are disposed in the plurality of holes 26 vertically penetrating the lower electrode 24, and the wafer lift pins 30 are fixed to the wafer lift pin supports 32. The wafer lift pins 30 allow the wafer W to be transported into the process chamber 12 by the robot arm (not shown) to be seated on the lower electrode 24 at the start of the process through a lift action. The wafer W is lifted from the lower electrode 24 so that a robot arm (not shown) may transport the wafer W to the outside of the process chamber 12.

The wafer lift pin support 32 is connected to the drive unit 36 disposed outside the process chamber 12 by a shaft 34 installed to penetrate the process chamber 12, and according to the driving of the drive unit 36. The wafer lift pin 30 is lifted while rising or falling. The driving unit 36 may be made of pneumatic or hydraulic cylinder.

On the other hand, since the shaft 34 is installed through the process chamber 12 as described above, airtight leakage may leak through the shaft 34 through the process chamber 12. In order to prevent this problem, the plasma etching apparatus 10 according to the present invention is installed in the process chamber 12 so as to surround the shaft 34, the O-ring seal structure 100 to maintain the airtight inside the process chamber 12 Has The O-ring seal structure 100 is installed in the process chamber 12 to surround the shaft 34, the stator 110 does not have a protruding edge on the outer surface and the contact with the shaft 34 The first O-ring 120 is inserted into the stator 110, and the second O-ring 122 is interposed between the stator 110 and the process chamber 12.

The stator 110 is fixed to the bottom of the process chamber 12 by fastening the flange 116 and the process chamber 12 provided in the lower region by the bolt 114. The stator 110 also serves as a guide means during the lifting motion of the shaft 34.

In general, pointed parts such as corners are more likely to cause arcing because electrons easily come out under concentrated electric fields. Therefore, in the present invention, the stator 110 is smoothly rounded so that its outer surface does not have protruding edges to prevent arcing. Preferably, the stator 110 may be formed in a cylindrical shape having an upper region of the dome shape 112. In addition, the flange 116 may also be smoothly rounded so that the edge 118 does not have protruding edges. The stator 110 may have various forms, for example, the shape of a polygonal pillar, which may be implemented by those skilled in the art, in addition to the above-described forms. Even in this case, the corners formed on the outer surface thereof should be smoothly rounded as described above.

In addition, the stator 110 may be made of a ceramic material. In this case, since the ceramic is close to the insulator, the possibility of arcing may be significantly lowered.

Meanwhile, the first O-ring 120 inserted into the stator 110 to be in contact with the shaft 34 is in close contact with the outer circumferential surface of the shaft 34 while the shaft 34 is being raised and lowered, thereby causing the shaft 34 of the process chamber 12 to be in contact with the shaft 34. ) It prevents leakage of airtightness that may occur through the penetration part.

The second o-ring 122 interposed between the stator 110 and the process chamber 12 prevents leakage of airtight that may occur between the bottom of the process chamber 12 and the flange 116.

Meanwhile, the etching process performed in the process chamber 12 is performed at a predetermined vacuum atmosphere and a high temperature state, so that the first o-ring 120 and the second o-ring 122 must be able to withstand such a process state. Therefore, the first O-ring 120 and the second O-ring 122 are preferably formed of a material of chromium stainless or titanium having low thermal expansion coefficient and high durability.

The aforementioned O-ring seal structure 100 can reduce the size of the equipment, easy to design, process and assemble, there is an advantage that can easily obtain an alternative standard when repairing.

Hereinafter, the operation of the plasma etching apparatus 10 having the O-ring seal structure according to the present invention will be described in detail.

First, a robot arm (not shown) introduces the wafer W into the process chamber 12 through the wafer entrance 14. At this time, when the wafer W is seated on the wafer lift pin 30 previously raised to a predetermined height, the shaft 34 is lowered by the driving unit 36 so that the wafer W is placed on the lower electrode 24. .

Then, the reaction gas carried through the gas supply pipe 20 is supplied between the upper electrode 16 and the lower electrode 24 by the upper electrode 16 serving as a shower head, and evenly distributed, the upper electrode ( A predetermined RF power is applied to the 16 and a bias power is applied to the lower electrode 24 to form an electric field between the upper electrode 16 and the lower electrode 24. The reaction gas is converted into a plasma state while being activated by the electric field, and the wafer W is etched through the converted plasma.

After the etching is completed, the wafer lift pin 30 is raised by the driving unit 36, and the wafer W is lifted from the lower electrode 24. Thereafter, the wafer W, which has been etched by the robot arm (not shown), is carried out of the process chamber 12 through the wafer entrance 14.

Leakage of the airtight which may occur through the shaft 34 through the process chamber 12 during the process is prevented through the O-ring seal structure 100 according to the present invention.

As mentioned above, although the present invention has been described with reference to the illustrated embodiments, it is only an example, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the scope of the present invention should be defined by the appended claims and their equivalents.

As described above, according to the plasma etching apparatus having an O-ring seal structure according to the present invention, by suppressing the occurrence of arcing that is often generated in the conventional bellows seal structure, the low peak voltage decreases and the low point reflecting power loss increases when RF is applied. By preventing the damage and damage to the wafer that can occur in the shaft, there is an advantage to improve the productivity by reducing the irregular PM.

Claims (4)

Process chamber; An upper electrode provided in the upper region of the process chamber; A lower electrode provided in the lower region of the process chamber and on which a wafer is placed; A wafer lift pin installed to penetrate the lower electrode to lift and lower the wafer; A shaft installed to penetrate the process chamber to elevate the wafer lift pin; An O-ring seal structure installed in the process chamber to surround the shaft to maintain an airtight inside the process chamber, wherein the O-ring seal structure is installed in the process chamber to surround the shaft, and has a rounded corner And a second o-ring interposed between the stator, the first o-ring inserted into the stator to be in contact with the shaft, and the second o-ring interposed between the stator and the process chamber. The method of claim 1, The stator is a plasma etching apparatus having an O-ring seal structure, characterized in that the upper region is a cylindrical having a dome shape. The method according to claim 1 or 2, The stator is a plasma etching apparatus having an O-ring seal structure, characterized in that made of a ceramic material. The method according to claim 1 or 2, The material of the first O-ring and the second O-ring is a plasma etching apparatus having an O-ring seal structure, characterized in that the chromium stainless or titanium.

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