This application claims the benefit of Korean Patent Application No. 2004-98198, filed on Nov. 26, 2004 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present general inventive concept relates to a plasma processing apparatus, and more particularly, to a plasma processing apparatus, which has a view port to allow observation of plasma state within a chamber.
2. Description of the Related Art
In semiconductor processing, plasma has been widely used for various applications, such as plasma ion etching, plasma physical vapor deposition (PVD), plasma chemical vapor deposition (CVD), plasma ashing, plasma chamber cleaning, and the like. Plasma processing equipment generally comprises a process chamber, a substrate support, a reactant gas supply, a radio frequency (RF) power supply, an exhaust pump, and the like.
In a plasma process, completion of the process is detected by measuring variation in plasma emission spectrum. For this purpose, the process chamber is provided with a view port to allow observation of an emission state of plasmas.
A conventional construction of a view port of the plasma processing equipment is disclosed in Korean Patent Laid-open Publication No. 2001-0072886. In this publication, the plasma processing equipment comprises a process chamber to receive a wafer in an inner space thereof for plasma generation, a susceptor constituting a lower electrode, a showerhead constituting an upper electrode, and the like. The bottom of the process chamber is connected to an exhaust pipe to maintain the inner space of the process chamber in a vacuum state of a predetermined level. The susceptor is connected to an RF power supply to form a high frequency electric field between the susceptor and the showerhead, thereby creating plasmas from reactant gases within the process chamber.
In the meantime, a shield member having a smaller diameter than that of the process chamber is equipped on a wall of the process chamber, and a window device, that is, the view port is disposed on the wall of the process chamber and the shield member to detect the plasma state. The window device comprises a window plate made of quartz, an optical guide made of aluminum and inserted into the shield member, and a cover plate made of sapphire and attached to the optical guide, in which the optical guide has an anodized surface.
Even though the wall of the process chamber is earth grounded, the insulating window plate is inserted into the wall of the process chamber, so that ground continuity is broken on the wall of the process chamber where the window plate is inserted thereto. This causes non-uniform distribution of the electric field, and non-uniform plasma formed within the process chamber, resulting in a non-uniform process on the wafer.
In this plasma processing equipment, the window plate, the optical guide, and the cover plate are inserted into the wall of the process chamber. However, even with this construction, since the window plate and the cover plate are made of the insulating material, and the surface of the aluminum optical guide has an insulating film formed thereon by the anodizing treatment, ground continuity with the wall of the process chamber is still not assured.
The present general inventive concept provides a plasma processing apparatus, which comprises a process chamber designed to ensure ground continuity on a wall of the processing chamber, thereby enhancing uniformity of a process.
Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
These and/or other aspects and advantages of the present general inventive concept may be achieved by providing a plasma processing apparatus comprising an earth-grounded chamber; a gas supply and a radio-frequency (RF) power supply to create plasma within the chamber, a view port formed through a chamber wall of the chamber to allow observation of the interior of the chamber, a transparent window disposed in the view port to transmit light created from the plasma therethrough, and a ground cover disposed in the view port in an earth grounded state to maintain ground continuity around the transparent window.
The ground cover may contact the chamber wall to form a contact surface, and the contact surface may be a bare surface to contact the view port to be in the earth grounded state.
The ground cover may have a plurality of holes formed therethrough to allow the light emitted from the plasma to pass through the ground cover.
The ground cover may be adapted to cover a front side of the transparent window facing the interior of the chamber.
The view port may be further provided with a frame to fix the transparent window to the view port.
The view port may be further provided with at least one O-ring to maintain air-tightness.
The view port may be further provided with a shielding net to prevent leakage of an RF electric field generated from the interior of the chamber, and an ultraviolet (UV) filter to shield against ultraviolet rays emitted by the plasma.
These and/or other aspects and advantages of the present general inventive concept will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, of which:
Reference will now be made in detail to the embodiments of the present general inventive concept, examples of which are illustrated in the accompanying drawings. The embodiments are described below to explain the present general inventive concept by referring to the figures.
Referring to
An exhaust port 104 is formed at one side of the chamber 100, and is in communication with a vacuum pump 105, which discharges the reactant gases within the chamber 100 during the process to maintain the vacuum state of the predetermined level within the chamber 100.
The gas supply 101 has a typical showerhead shape and is connected to the RF power supply 102 to constitute an upper electrode, and the substrate support 103 is provided with a lower electrode (now shown), so that an RF electric field is created between the upper electrode and the lower electrode.
Meanwhile, the chamber 100 is generally made of an electrically conductive material, such as aluminum, and is earth grounded. The chamber 100 has an opening and a view port 200 formed through one wall thereof and disposed in the opening thereof to allow observation of a state of the plasma created within the chamber 100. Light generated from the plasma during the process is emitted to an outside through the view port 200, so that a user of the plasma processing apparatus can determine regularity and progress of the process by detecting the light by the naked eye or a measuring device.
The detailed constructions of the chamber 100, the gas supply 101, the RF power supply 102, the substrate support 103, and the like as described above can be changed according to a type of the process, and these constructions are disclosed only as an example in this embodiment. The construction of the view port 200 will be described in detail as follows.
Referring to
The transparent window 210 comprises a circular base plate 211 facing an outside of the chamber 100, and an extension 212 extended from the base plate 211 to the interior of the chamber 100, in which the extension 212 has a thickness thicker than that of the base plate 211 and a diameter smaller than that of the base plate 211. The transparent window 210 can be made of quartz. However, the present invention is not limited to quartz, and the transparent window 210 may be made of sapphire or other transparent materials instead of the quartz.
The frame 220 holding the periphery of the base plate 211 of the transparent window 210 comprises an inner frame 221 disposed towards the interior of the chamber 100, and an outer frame 222 disposed towards the outer portion of the chamber 100. The outer frame 222 has a receipt recess 222a formed thereon to receive the base plate 211 of the transparent window 210. Accordingly, the outer frame 222 surrounds a circumferential surface and a rear peripheral surface of the base plate 211, and the inner frame 221 surrounds a front peripheral surface of the base plate 211. A first O-ring 251 is interposed between the inner frame 221 and the wall of the chamber 100 for air-tightness, so that air is prevented from being introduced into the chamber 100 during the process, and the interior of the chamber 100 is prevented from being contaminated by the air while maintaining the inside of the chamber 100 in the vacuum state of the predetermined level within the chamber 100. Additionally, second and third O-rings 252 and 253 are interposed between the inner frame 221 and the base plate 211, and between the outer frame 222 and the base plate 211, respectively. The second and third O-rings 252 and 253 serve not only to maintain air-tightness, but also to prevent the transparent window 210 from being broken due to an excessive impact directly transmitted thereto upon contact of the quartz transparent window 210 to the frame 220. The inner frame 221 and the outer frame 222 have O-ring grooves 221a, 221b, and 222b formed thereon to install the O-rings 251, 252 and 253, respectively. The frame 220 is fixed to the wall of the chamber 100 by a first fixing bolt 261, which is fastened through the outer circumference of the frame 220 to the wall of the chamber 100. For this purpose, screw holes 221c and 222c are formed through the inner frame 221 and the outer frame 222 at corresponding positions thereof, respectively.
The ground cover 230 serves to maintain the ground continuity around the transparent window 210. The ground cover 230 surrounds some portion of the front side of the extension 212 of the transparent window 210 as shown in
The ground cover 230 is made of aluminum, which is an electrically conductive material. in order to enhance a abrasive resistance, thermal resistance, and the like, aluminum components may have a coated surface formed by an anodizing treatment. An optical guide of a conventional technology as mentioned above has the anodized surface, and the anodized coating on the surface acts as an electrically insulating material. According to this embodiment, however, in order to maintain the ground continuity with the wall of the chamber 100, the skirt portion 231 of the ground cover 230 has opposite sides respectively constituted by bare surfaces 231a and 231b, from which the anodized coating is removed or is not formed, and electrically connected to the wall of the chamber 100 and the inner frame 221. Accordingly, together with the wall of the chamber 100, the ground cover 230 is also in an earth grounded state. At this time, the wall of the chamber 100 and the inner frame 221 may contact the bare surfaces 231a and 231b of the ground cover 230. In this embodiment, only the opposite sides of the skirt portion 231 are constituted by the bare surfaces 231a and 231b, and other portions of the ground cover 230 are formed with the anodized coating 232. However, the present general inventive concept is not limited to this construction, and an entire surface contacting the wall of the chamber 100 may be constituted by the bare surfaces 231a and 231b, if necessary.
The outer cover 240 is disposed on the outside of the outer frame 222. A shielding net 271 made of stainless steel to prevent the RF electric field generated within the chamber 100 from escaping, and an ultraviolet (UV) filter 272 to shield against ultraviolet rays emitted by the plasma are equipped between the outer cover 240 and the outer frame 220. The shielding net 271 and the UV filter 272 are provided to ensure the security of users viewings the interior of the chamber 100. The outer cover 240 has a plurality of screw holes 240a formed through the circumference of the outer cover 240 to fasten a plurality of second fixing bolts 262, which fix the outer cover 240 to the outer frame 220.
In the plasma processing apparatus according to the present general inventive concept, the transparent window 210 disposed in the view port 200 is surrounded by the ground cover 230 electrically contacting the wall of the chamber 100. Accordingly, ground continuity is maintained around the transparent window 210, and uniformity of the electric field and the plasma is ensured within the chamber 100.
As apparent from the above description, the plasma processing apparatus according to the present general inventive concept is provided with the ground cover, which can ensure the ground continuity around the view port, thereby providing uniformity of the electric field and the plasma within the chamber. Accordingly, the uniformity of the process and the yield of the wafer are enhanced.
Although a few embodiments of the present general inventive concept have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.
Number | Date | Country | Kind |
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2004-98198 | Nov 2004 | KR | national |