US20060027327A1

US20060027327A1 - Apparatus and methods for a low inductance plasma chamber

Info

Publication number: US20060027327A1
Application number: US11/179,035
Authority: US
Inventors: Carl Sorensen; John White; Suhail Anwar
Original assignee: Applied Materials Inc
Current assignee: Applied Materials Inc
Priority date: 2004-07-12
Filing date: 2005-07-11
Publication date: 2006-02-09
Also published as: CN100426941C; TWI303954B; JP5670694B2; TW200608842A; TW200608841A; JP2011066907A; US7570130B2; CN1770238A; CN1770950A; KR20060050086A; KR20060050031A; KR100767812B1; US20060017386A1; TWI356656B; JP2006101480A; KR100648336B1; JP2006032954A; CN100511357C

Abstract

In certain aspects, a plasma chamber is provided that has (1) a chamber size of at least about 1.8 by 2.0 meters; and (2) an effective inductance having an inductive reactance of not more than about 12-15 ohms. The plasma chamber may be used, for example, to process substrates used for flat panel displays. Numerous other aspects are provided.

Description

This application claims priority from U.S. Provisional Patent Application Ser. No. 60/587,195, filed Jul. 12, 2004, and entitled “APPARATUS AND METHODS FOR A LOW INDUCTANCE PLASMA CHAMBER AND/OR A FIXED IMPEDANCE TRANSFORMATION NETWORK FOR USE IN CONNECTION WITH THE SAME”, which is hereby incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention relates to electronic device manufacturing and, more particularly, to apparatus and methods for a low inductance plasma chamber.

BACKGROUND OF THE INVENTION

Plasma chambers are typically used to process substrates such as semiconductor wafers, glass plates, polymer substrates, etc. A plasma chamber may contain conducting elements which, when energized by a radio frequency (RF) signal, behave like inductors, such as coils or chokes, and/or like capacitors. These “effective” inductances and/or “effective” capacitances, when driven by an RF signal, generate reactance components in the electrical circuit defined by the plasma chamber and its components. These reactance components can substantially increase the electrical impedance associated with the plasma chamber and the amount of voltage needed to drive the same. As a result, plasma chambers can be inefficient and can experience reliability problems.

SUMMARY OF THE INVENTION

In certain aspects of the invention, a plasma chamber is provided that has (1) a chamber size of at least about 1.8 by 2.0 meters; and (2) an effective inductance having an inductive reactance of not more than about 12-15 ohms.
In certain aspects of the invention, a method is provided that includes providing a plasma chamber having (1) a chamber size of at least about 1.8 by 2.0 meters; and (2) an effective inductance having an inductive reactance of not more than about 12-15 ohms. The method also includes employing the plasma chamber to process substrates used for flat panel displays.
In certain aspects of the invention, a plasma chamber is provided that includes (1) a first chamber portion having an inner surface; (2) a second chamber portion coupled to the first chamber portion so as to define an inner chamber region; (3) a first electrode positioned a first distance from the first chamber portion; (4) a second electrode positioned between the first electrode and the second chamber portion so as to define a plasma region between the first and second electrodes; and (5) a conductive piece positioned between the first chamber portion and the first electrode and coupled to the first chamber portion so as to create a current path that reduces an effective inductance of the plasma chamber.
In certain aspects of the invention, a plasma chamber is provided that includes (1) a first chamber portion having an inner surface; (2) a second chamber portion coupled to the first chamber portion so as to define an inner chamber region; (3) a first electrode positioned a first distance from the first chamber portion; and (4) a second electrode positioned between the first electrode and the second chamber portion so as to define a plasma region between the first and second electrodes. The first chamber portion has an increased thickness that creates a current path that reduces an effective inductance of the plasma chamber. Numerous other aspects are provided.
Other features and aspects of the present invention will become more fully apparent from the following detailed description, the appended claims and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary embodiment of the low inductance plasma chamber of the present invention; and
FIG. 2 illustrates another exemplary embodiment of the low inductance plasma chamber of the present invention.

DETAILED DESCRIPTION

The present invention provides a low inductance plasma chamber which can be operated more efficiently and more reliably, and which can be driven or powered by a lower voltage.
FIG. 1 illustrates a first exemplary embodiment of a low inductance plasma chamber of the present invention which is designated generally by the reference numeral 100. With reference to FIG. 1, the low inductance plasma chamber 100 includes a vacuum chamber enclosure 102. In the exemplary embodiment of FIG. 1, the vacuum chamber enclosure 102 can be any suitable chamber enclosure such as those chambers which are utilized in the AKT, Inc. Plasma Chamber Models 20K, 25K and/or 25KA.
The vacuum chamber enclosure 102 can be manufactured from any suitable material(s) consistent with its use in conjunction with the apparatus and methods of the present invention. In an exemplary embodiment, the vacuum chamber 102 and its components are manufactured from Aluminum.
In the exemplary embodiment of FIG. 1, the vacuum chamber enclosure 102 includes an upper vacuum enclosure 104 and a lower vacuum enclosure 106. The upper vacuum enclosure 104 and the lower vacuum enclosure 106 are coupled or sealed together in any appropriate and/or suitable manner, as shown, so as to form the vacuum chamber 102 of the low inductance plasma chamber 100. For example, a sealing element such as an o-ring (not shown) may be used to seal the upper vacuum enclosure 104 relative to the lower vacuum enclosure 106.
The inner walls of the upper vacuum enclosure 104 and the inner walls of the lower vacuum enclosure 106 include electrically conducting materials so as to facilitate the conduction of electrical current along the same within the plasma chamber 100 as described herein. In an exemplary embodiment, the inside walls of the upper vacuum enclosure 104 and the inside walls of the lower vacuum enclosure 106 can be manufactured from aluminum. In other embodiments, the inside walls of the upper vacuum enclosure 104 and/or the inside walls of the lower vacuum enclosure 106 can be manufactured from any other suitable electrical conducting material such as, but not limited to, any suitable non-ferrous material, Brass, or any suitable Nickel Alloy material.
With reference to FIG. 1, the plasma chamber 100 also includes a pair of electrodes, including an upper electrode 108 and a lower electrode 110, positioned inside the plasma chamber 100. The lower electrode 110, in the exemplary embodiment, can be used to support a substrate which is to be processed in the plasma chamber 100. The upper electrode 108 has a lower surface 108A which faces the lower electrode 110 and an upper surface 108B which faces a top inner wall of the upper vacuum enclosure 104. The lower electrode 110 has an upper surface 110A which faces the upper electrode 108 and which supports a substrate during processing and a lower surface 110B which faces a bottom inner wall of the lower vacuum enclosure 106.
As noted above, in an exemplary embodiment, the lower electrode 110 is adapted to support a substrate which is to be processed. The lower electrode can also include an inner region or chamber 110C shown in cut-away form in FIG. 1, and at least one heating element or heating element system 110D. The heating element or heating element system 110D can be a resistive heating element or heating element system, or any other suitable heating element or system, which can be used to heat the substrate supported on the lower electrode 110. The lower electrode 110, in an exemplary embodiment, can also be electrically grounded within the low inductance plasma chamber 100.
The upper electrode 108 and the lower electrode 110 are spaced a pre-determined distance from one another so as to form a gap between the same. In one embodiment, the pre-determined distance may be about 0.5-1.5 inches, although other distances may be employed. As will be described herein, a plasma or plasma body 111 composed of a processing gas used in a respective electronic device and/or substrate processing step will be formed in the gap or plasma region 112 located between the upper electrode 108 and the lower electrode 110. In an exemplary embodiment, the processing gas and/or the plasma 111 which can be utilized may include silane, ammonia, hydrogen, nitrogen argon or any other suitable processing gas or gas mixture.
The upper electrode 108 and the lower electrode 110 can be, for example, of the type utilized in the AKT, Inc. Plasma Chamber Models 20K, 25K and/or 25KA or equivalents thereof. In an exemplary embodiment, the upper electrode 108 and the lower electrode 110 can each be manufactured from aluminum. The upper electrode 108 and the lower electrode 110 can also each be manufactured from any other suitable electrical conducting material such as, but not limited to, any suitable non-ferrous material, Brass, or any suitable Nickel Alloy material.
The upper electrode 108 can be a hollow showerhead type electrode having a reservoir 108C located therein for receiving processing gas and a series of apertures or spray jets 114 through the lower surface 108A thereof for dispensing the processing gas as described herein. For example, the upper electrode 108 can be any of the upper electrodes utilized in the AKT, Inc. Plasma Chamber Models 20K, 25K and/or 25KA or equivalents thereof. In an exemplary embodiment, the upper electrode 108, depending upon the application and size of the same, can have in excess of 50,000 apertures 114 which are approximately equal in size so as to achieve an equal flow of gas from each aperture 114. Other numbers of spray jets or apertures may be used.
The upper electrode 108 can receive a respective processing gas which is used in a processing operation from a gas supply 150 via a gas feed tube 116 which is coupled to the upper electrode 108, as shown in FIG. 1. In at least one embodiment, the gas feed tube 116 can be electrically coupled to the upper electrode 108, and manufactured from an electrically conducting material. For example, the gas feed tube can be manufactured from aluminum or any suitable electrical conducting material such as, but not limited to, any suitable non-ferrous material, Brass, or any suitable Nickel Alloy material.
The processing gas from the gas supply 150 can be provided under pressure via the gas feed tube 116 into the inside reservoir 108C of the upper electrode 108 and dispersed through the apertures 114 into the gap 112 between the upper electrode 108 and the lower electrode 110 so as to form a plasma body 111 in the gap 112. In an exemplary embodiment, the pressure of the processing gas in the reservoir 108C can be about 10 Torr while the pressure of the plasma in the plasma body 111 can be about 1 Torr. Other pressures may be employed. By utilizing a higher gas pressure in the reservoir 108C, a greater flow of the processing gas through the apertures 114 can be achieved.
The low inductance plasma chamber 100 can also include a support column 118 which is coupled to, and supports, the lower electrode 110 at the lower portion of the lower vacuum enclosure 106, as shown. In the exemplary embodiment of FIG. 1, the support column 118 is manufactured from aluminum, and can be any suitable support column such as, but not limited to those support columns utilized in the AKT, Inc. Plasma Chamber Models 20K, 25K and/or 25KA or equivalents thereof. The support column 118 can also be manufactured from any other suitable electrical conducting material such as, but not limited to, any suitable non-ferrous material, Brass, or any suitable Nickel Alloy material.
The lower region 120 of the lower vacuum enclosure 106 includes a flexible coupling 122. The flexible coupling 122 is manufactured from aluminum and/or any other suitable material(s) in any suitable manner consistent with its use in the apparatus 100 of the present invention. In an exemplary embodiment, the flexible coupling 122 can be any flexible coupling such as, but not limited to, those flexible couplings utilized in the AKT, Inc. Plasma Chamber Models 20K, 25K and/or 25KA or equivalents thereof. The flexible coupling 122 can also be manufactured from any other suitable electrical conducting material such as, but not limited to, any suitable non-ferrous material, Brass, or any suitable Nickel Alloy material.
The low inductance plasma chamber 100 can also include an RF delivery cover box 124 which can be connected to the top portion of the upper vacuum enclosure 104, as shown. The RF delivery cover box 124 can also be electrically coupled to the inside wall of the upper vacuum enclosure 104. The RF delivery box 124, in the exemplary embodiment, can be adapted to supply an alternating current signal or an RF signal current from an RF Signal Supply 160 to the gas feed tube 116 and to provide a return line of alternating current or RF current from the low inductance plasma chamber 100 to the RF signal source 160.
The RF delivery cover box 124 can be made from aluminum or any other suitable material such as, for example, a non-ferrous material, Brass, or a Nickel Alloy conducting material. In an exemplary embodiment, the RF delivery cover box 124 can be any suitable electrical delivery cover box device such as, but not limited to, those RF delivery cover boxes utilized in the AKT, Inc. Plasma Chamber Models 20K, 25K and/or 25KA or equivalents thereof.
The low inductance plasma chamber 100 also includes a conducting element such as a pan structure 126 which is coupled to, or attached to, the top inside wall of the upper vacuum enclosure 104, as shown. The pan structure 126 is a conducting element. In the exemplary embodiment of FIG. 1, the pan structure 126 can be manufactured from aluminum. The pan structure 126 can also be manufactured from any suitable electrical conducting material such as, but not limited to, any suitable non-ferrous material, Brass, or any suitable Nickel Alloy material. The pan structure 126 can be sized and shaped in any appropriate manner depending upon the size and shape of the vacuum chamber enclosure 102 and/or the upper vacuum chamber enclosure 104. In an exemplary embodiment, the pan structure 126 is formed from aluminum, and has a thickness of about 0.125 inches, a height of about 3 inches, a width of about 1.8 meters and a length of about 2 meters for a plasma chamber adapted to process 1.8 meter×2 meter substrates. Other pan shapes, dimensions and/or materials may be used.
The pan structure 126 can be positioned a pre-determined distance from the second surface 108B of the upper electrode 108. The pre-determined distance between the pan structure 126 and the second surface 108B of the upper electrode 108 defines a gap between the respective elements. In one embodiment, the distance between the pan structure 126 and the second surface 108B of the upper electrode 108 is about 1.5 inches or less, although other distances may be used. As another example, a spacing of about 0.5 to about 2 inches may be used and more preferably about 1-2 inches.
When it is desired to utilize the low inductance plasma chamber 100 of FIG. 1 to perform a processing operation or step on a substrate, the following exemplary process can be performed. A process gas can be supplied from the gas supply 150 to the gas feed tube 116 under suitable pressure while an alternating current or RF signal current can be provided from the RF Signal Supply 160 to the outside surface of the gas feed tube 116.
The process gas flows inside the gas feed tube 116 and into the reservoir 108C inside the upper electrode 108. The process gas is then forced out through the series of apertures 114 in the surface 108A of the upper electrode 108 and into the gap 112 forming plasma body 111.
For ease of understanding and for purposes of illustration, the following description of the current flow of the RF signal current will be described for a positive half cycle of the same.
The RF signal current, which is introduced to the outside surface of the gas feed tube 116, as shown by current arrow 130, flows downwardly as shown by arrows 131 to the upper surface 108B of the upper electrode 108. The RF signal current continues to flow radially outwardly from the base of the gas feed tube 116 onto and along the upper surface 108B of the upper electrode 108, as shown by current arrows 132. At the outer perimeter of the upper electrode 108, the RF signal current flows around the edge of the upper electrode 108 and is capacitively coupled into the plasma body 111 in the gap 112. In an exemplary embodiment, the RF signal current has a frequency at or approximately at 13.56 MHz. In another embodiment, a frequency of about 27 MHz may be used. It is to be understood, however, that any appropriate or suitable RF signal frequency can be employed depending upon the plasma chamber utilized, its dimensions, and the operation(s) to be performed.
The RF signal current is then capacitively coupled from the bottom of the plasma body 111 to the upper surface 110A of the lower electrode 110. The RF signal current then flows radially outwardly across the upper surface 110A of the lower electrode 110. The RF signal current then flows around the outer edge of the lower electrode 110 and onto its lower surface 110B where it flows radially inwardly toward and to the support column 118 as shown by the current arrows. The RF signal current then flows downwardly and along the outer surface of the support column 118. At the bottom of the support column 118, the RF signal current turns upwardly and flows along the flexible coupling 122 and radially outwardly along the inside walls of the lower vacuum enclosure 106. The RF signal current continues to flow upwardly and along the inside vertical walls of the respective lower vacuum chamber enclosure 106 and the upper vacuum chamber enclosure 104.
The RF signal current then flows along the top of the inside wall of the upper vacuum enclosure 104 and along the bottom surface 126A of the pan structure 126, as shown. The RF signal current flows, as shown by current arrows 133, along the bottom surface 126A of the pan structure 126 to the inside of the RF delivery box cover 124 and is returned to the RF Signal Supply 160 as shown by current arrow 135. The direction and flow of the RF signal current, through the low inductance plasma chamber 100, would then be reversed for the next, or negative, half cycle of the RF signal.
With reference once again to FIG. 1, without the pan structure 126, the RF signal current flowing along the inside wall of the upper vacuum enclosure 104 would flow along the top wall of the upper vacuum enclosure 104, as shown by the dashed line arrows 140, and into the inside of the RF delivery box cover 124.
As shown in FIG. 1, the RF signal current flows along the top surface 108B of the upper electrode 108 in a first direction, as shown by current arrow 132, while current flows along the surface 126A of the pan structure 126 in an opposite direction as shown by current arrow 133. The proximity of the two conductors, namely, the upper surface 108B of the upper electrode 108 and the pan surface 126A of the pan structure 126, to one another in the low inductance plasma chamber 100, and the flow of the respective currents on or along each in directions opposite to one another, creates a parallel plane transmission line in the low inductance plasma chamber 100. As a result, the upper surface 108B of the upper electrode 108 and the pan surface 126A of the pan structure 126, behave as an inductor having an “effective” inductance which is directly proportional to the size of the gap or the amount of separation between the upper surface 108B of the upper electrode 108 and the surface 126A of the pan structure 126. The placement of the respective current carrying conductors 108B and 126A closer to one another, as illustrated in the exemplary embodiment of FIG. 1, and as effectuated by the use of the pan structure 126, serves to reduce the “effective” inductance, and the resulting inductive reactance, of the electrical circuit which exists in the low inductance plasma chamber 100.
The “effective” inductance created by the parallel transmission line formed by the surface 126A of the pan structure 126 and the upper surface 108B of the upper electrode 108 is electrically in series with an “effective” resistance of the low inductance plasma chamber 100 which includes the resistance of the plasma body 111 and any other resistances associated with any of the components of the low inductance plasma chamber 100.
By reducing the inductance and the inductive reactance of this series electrical circuit inside the low inductance plasma chamber 100, the reactance, as well as the total impedance, of the electrical circuit are reduced. As a result, the input voltage needed to drive the low inductance plasma chamber 100 is reduced. The reduction of the input voltage required to drive the low inductance plasma chamber 100 reduces stress or stresses on or in other portions of the RF signal supply and/or in other components of the low inductance plasma chamber 100 and provides for increased efficiencies and reliability in the operation of the same.
In another exemplary embodiment of the present invention, a conducting element can be formed from an inner wall of a low inductance plasma chamber, thereby dispensing with the need to use a separate pan structure. For example, FIG. 2 illustrates a second exemplary embodiment of the low inductance plasma chamber or apparatus of the present invention which is designated generally by the reference numeral 200. With reference to FIG. 2, the low inductance plasma chamber 200 includes a vacuum chamber enclosure 202.
The vacuum chamber enclosure 202 can be manufactured from any suitable material(s) consistent with its use in conjunction with the apparatus and methods of the present invention. In an exemplary embodiment, the vacuum chamber 202 and its components are manufactured from Aluminum.
Referring to FIG. 2, the vacuum chamber enclosure 202 includes an upper vacuum enclosure 204 and a lower vacuum enclosure 206. The upper vacuum enclosure 204 and the lower vacuum enclosure 206 are coupled or sealed together in any appropriate and/or suitable manner, as shown, so as to form the vacuum chamber enclosure 202 of the low inductance plasma chamber 200. For example, a sealing element such as an o-ring (not shown) may be used to seal the upper vacuum enclosure 204 relative to the lower vacuum enclosure 206.
The inner walls of the upper vacuum enclosure 204 and the inner walls of the lower vacuum enclosure 206 include electrically conducting materials so as to facilitate the conduction of electrical current along the same within the plasma chamber 200 as described herein. For example, the inside walls of the upper vacuum enclosure 204 and the inside walls of the lower vacuum enclosure 206 can be manufactured from aluminum. In other embodiments, the inside walls of the upper vacuum enclosure 204 and the inside walls of the lower vacuum enclosure 206 can be manufactured from any suitable electrical conducting material such as, but not limited to, any suitable non-ferrous material, Brass, or any suitable Nickel Alloy material.
The plasma chamber 200 also includes a pair of electrodes, including an upper electrode 208 and a lower electrode 210, positioned inside the plasma chamber 200. The lower electrode 210, in the exemplary embodiment, can be used to support a substrate which is to be processed in the plasma chamber 200. The upper electrode 208 has a lower surface 208A which faces the lower electrode 210 and an upper surface 208B which faces a top inner wall of the upper vacuum enclosure 204. The lower electrode 210 has an upper surface 210A which faces the upper electrode 208 and which supports a substrate during processing and a lower surface 210B which faces a bottom inner wall of the lower vacuum enclosure 206.
As noted above, in an exemplary embodiment, the lower electrode 210 is adapted to support a substrate which is to be processed. For example, the lower electrode can also include an inner region or chamber 210C shown in cut-away form in FIG. 2, and at least one heating element or heating element system 210D. The heating element or heating element system 210D can be a resistive heating element or heating element system, or any other suitable heating element or heating element system, which can be used to heat the substrate supported on the lower electrode 210. The lower electrode 210, in an exemplary embodiment, can also be electrically grounded within the low inductance plasma chamber 200.
The upper electrode 208 and the lower electrode 210 are spaced a pre-determined distance from one another so as to form a gap between the same. In one embodiment, the electrodes 208, 210 may be spaced by about 0.5-1.5 inches, although other spacings may be used. As will be described herein, a plasma or plasma body 211 composed of a processing gas used in a respective substrate processing step will be formed in the gap or a plasma region 212 located between the upper electrode 208 and the lower electrode 210. In an exemplary embodiment, the processing gas and/or the plasma or plasma body 211 which can be utilized can include silane, ammonia, hydrogen, nitrogen argon or any other suitable processing gas or gas mixture.
The upper electrode 208 and the lower electrode 210 can, for example, be manufactured from aluminum. The upper electrode 208 and the lower electrode 210 can also each be manufactured from any other suitable electrical conducting material such as, but not limited to, any suitable non-ferrous material, Brass, or any suitable Nickel Alloy material.
The upper electrode 208 can be a hollow showerhead type electrode having a reservoir 208C located therein for receiving processing gas and a series of apertures or spray jets 214 through the lower surface 208A thereof for dispensing the processing gas as described herein. In an exemplary embodiment, the upper electrode 208, depending upon the application and size of the same, can for example, have in excess of 70,000 apertures 214 which are approximately equal in size so as to achieve an equal flow of gas from each aperture 214. Other numbers of spray jets or apertures may be used.
The upper electrode 208 can receive a respective processing gas which is used in a respective processing operation from a gas supply 250 via a gas feed tube 216 which is coupled to the upper electrode 208 as shown in FIG. 2. In an exemplary embodiment, the gas feed tube 216 can be electrically coupled to the upper electrode 208. The gas feed tube 216 can be manufactured from an electrically conducting material, such as aluminum or any other suitable electrical conducting material such as, but not limited to, any suitable non-ferrous material, Brass or any suitable Nickel Alloy material.
The processing gas from the gas supply 250 can be provided under pressure via the gas feed tube 216 into the inside reservoir 208C of the upper electrode 208 and dispersed through the apertures 214 into the gap between the upper electrode 208 and the lower electrode 210 so as to form a plasma body 211 in the plasma region 212. In any exemplary embodiment, the pressure of the processing gas in the reservoir 208C can be about 10 Torr while the pressure of the plasma in the plasma body 211 can be about 1 Torr. Other pressures may be employed. By utilizing a higher gas pressure in the reservoir 208C, a greater flow of the processing gas through the apertures 214 can be achieved.
The low inductance plasma chamber 200 can also include a support column 218 which is coupled to, and supports, the lower electrode 210 at the lower portion of the lower vacuum enclosure 206, as shown. In the exemplary embodiment of FIG. 2, the support column 218 is manufactured from aluminum. The support column 218 can be any suitable support column, and can also be manufactured from any other suitable electrical conducting material such as, but not limited to, any suitable non-ferrous material, Brass, or any suitable Nickel Alloy material.
The lower region 220 of the lower vacuum enclosure 206 includes a flexible coupling 222. In an exemplary embodiment, the flexible coupling 222 is manufactured from aluminum and/or any other suitable material(s) in any suitable manner consistent with its use in the apparatus 200 of the present invention (e.g., any suitable non-ferrous material, Brass, or any suitable Nickel Alloy material). The flexible coupling 222 may be similar to the flexible coupling 122 of FIG. 1.
The low inductance plasma chamber 200 can also include and RF delivery cover box 224 which can be connected to the top portion of the upper vacuum enclosure 204, as shown. The RF delivery cover box 224 can also be electrically coupled to the inside wall of the upper vacuum enclosure 204. The RF delivery box 224, in the exemplary embodiment, can be adapted to supply an alternating current signal or an RF signal current from an RF Signal Supply 260 to the gas feed tube 216 and to provide a return line of alternating current or RF current from the low inductance plasma chamber 200 to the RF signal source 260.
The RF delivery cover box 224 can be made of any suitable material, including a conducting material such as, for example, Aluminum, and/or any other non-ferrous material, Brass, or Nickel Alloy conducting material. In the exemplary embodiment, the conducting material used in the RF delivery cover box 224 can be Aluminum. In an exemplary embodiment, the RF delivery cover box 224 can be any suitable electrical delivery cover box device, and may be similar to the RF delivery cover box 124 of FIG. 1.
The low inductance plasma chamber 200 also includes a conducting element 226 which is formed as, in, with, and/or on, the top inside wall of the upper vacuum enclosure 204, as shown in FIG. 2. In the exemplary embodiment of FIG. 2, the conducting element 226 can be manufactured from aluminum. The conducting element 226 can also be manufactured from any suitable electrical conducting material such as, but not limited to, any suitable non-ferrous material, Brass, or any suitable Nickel Alloy material. The conducting element 226 can be shaped in any appropriate manner depending upon the size and shape of the vacuum chamber enclosure 202 and/or the upper vacuum chamber enclosure 204. In an exemplary embodiment, the conducting element 226 is formed and positioned to be parallel with, or substantially parallel with, and to be located at a pre-determined distance from, the second surface 208B of the upper electrode 208. The pre-determined distance between the conducting element 226 and the second surface 208B of the upper electrode 208 defines a gap between the respective elements. In at least one embodiment, the distance between the conducting element 226 and the second surface 208B of the upper electrode 208 is about 1.5-2 inches, and more preferably about 1.75 inches, although other distances may be employed. As another example, a spacing of about 0.25 to about 2 inches may be used and more preferably about 1-2 inches.
When it is desired to utilize the low inductance plasma chamber 200 of FIG. 2 to perform a processing operation or step on a substrate, the following exemplary process can be performed. A process gas can be supplied from the gas supply 250 to the gas feed tube 216 under suitable pressure while an alternating current or RF signal current can be provided from the RF Signal Supply 260 to the outside surface of the gas feed tube 216.
The process gas flows inside the gas feed tube 216 and into the reservoir 208C inside the upper electrode 208. The process gas is then forced out through the series of apertures 214 in the surface 208A of the upper electrode 208 and into the plasma region 212 forming plasma body 211.
For ease of understanding and for purposes of illustration, the following description of the current flow of the RF signal current will be described for a positive half cycle of the same.
The RF signal current, which is introduced to the outside surface of the gas feed tube 216, as shown by current arrow 230, flows downwardly as shown by arrows 231 to the upper surface 208B of the upper electrode 208. The RF signal current continues to flow radially outwardly from the base of the gas feed tube 216 onto and along the upper surface 208B of the upper electrode 208, as shown by current arrows 232. At the outer perimeter of the upper electrode 208, the RF signal current flows around the edge of the upper electrode 208 and is capacitively coupled into the plasma body 211 in the plasma region 212. In an exemplary embodiment, the RF signal current has a frequency at or approximately at 13.56 MHz. It is to be understood, however, that any appropriate or suitable RF signal frequency can be employed depending upon the plasma chamber utilized, its dimensions, and the operation(s) to be performed.
The RF signal current is then capacitively coupled from the bottom of the plasma body 211 to the upper surface 210A of the lower electrode 210. The RF signal current then flows radially outwardly across the upper surface 210A of the lower electrode 210. The RF signal current then flows around the outer edge of the lower electrode 210 and onto its lower surface 210B where it flows radially inwardly toward and to the support column 218 as shown by the current arrows. The RF signal current then flows downwardly and along the outer surface of the support column 218. At the bottom of the support column 218, the RF signal current turns upwardly and flows along the flexible coupling 222 and radially outwardly along the inside walls of the lower vacuum enclosure 206. The RF signal current continues to flow upwardly and along the inside vertical walls of the respective lower vacuum chamber enclosure 206 and the upper vacuum chamber enclosure 204.
The RF signal current then flows along the top of the inside wall of the upper vacuum enclosure 204 and along the surface 226A of the conducting element 226, as shown. The RF signal current flows, as shown by current arrows 233, along the surface 226A of the conducting element 226 to the inside of the RF delivery box cover 224 and is returned to the RF Signal Supply 260 as shown by current arrow 235. The direction and flow of the RF signal current, through the low inductance plasma chamber 200, would then be reversed for the next, or negative, half cycle of the RF signal.
As shown in FIG. 2, the RF signal current flows along the top surface 208B of the upper electrode 208 in a first direction, as shown by current arrow 232, while current flows along the surface 226A of the conducting element 226 in an opposite direction as shown by current arrow 233. The proximity of the two conductors, namely, the upper surface 208B of the upper electrode 208 and the surface 226A of the conducting element 226, to one another in the low inductance plasma chamber 200, and the flow of the respective currents on or along each in directions opposite to one another, creates a parallel plane transmission line in the low inductance plasma chamber 200.
As a result, the upper surface 208B of the upper electrode 208 and the surface 226A of the conducting element 226, behave as an inductor having an “effective” inductance which is directly proportional to the size of the gap or the amount of separation between the upper surface 208B of the upper electrode 208 and the surface 226A of the conducting element 226. The placement of the respective current carrying conductors 208B and 226A relative to each other serves to reduce the “effective” inductance, and the resulting inductive reactance, of the electrical circuit which exists in the low inductance plasma chamber 200.
The “effective” inductance created by the parallel transmission line formed by the surface 226A of the conducting element 226 and the upper surface 208B of the upper electrode 208 is electrically in series with an “effective” resistance of the low inductance plasma chamber 200 which includes the resistance of the plasma body 211 and any other resistances associated with any of the components of the low inductance plasma chamber 200.
By reducing the inductance and the inductive reactance of this series electrical circuit inside the low inductance plasma chamber 200, the reactance, as well as the total impedance of the electrical circuit, are reduced. As a result, the input voltage needed to drive the low inductance plasma chamber 200 is reduced. The reduction of the input voltage required to drive the low inductance plasma chamber 200 reduces stress or stresses on or in other portions of the RF signal supply and/or in other components of the low inductance plasma chamber 200 and provides for increased efficiencies and reliability in the operation of the same.
In an exemplary embodiment, the dimensions of the low inductance plasma chamber 100 or 200 can result in an “effective” inductance having an inductive reactance of approximately 12-15 ohms (inductive) and an “effective” resistance of approximately 0.3 to 2.0 ohms for a chamber size of about 1.8 meters by 2.0 meters or greater.
The foregoing description discloses only exemplary embodiments of the invention. Modifications of the above disclosed apparatus and method which fall within the scope of the invention will be readily apparent to those of ordinary skill in the art. For instance, in at least one embodiment of the invention, a method is provided that includes the steps of providing a plasma chamber having (1) a chamber size of at least about 1.8 by 2.0 meters; and (2) an effective inductance having an inductive reactance of not more than about 12-15 ohms. The method further includes the step of employing the plasma chamber to process substrates used for flat panel displays. The plasma chamber also may have an effective resistance of not more than about 0.3 to 2.0 ohms.
Accordingly, while the present invention has been disclosed in connection with exemplary embodiments thereof, it should be understood that other embodiments may fall within the spirit and scope of the invention, as defined by the following claims.

Claims

1. A plasma chamber having:

a chamber size of at least about 1.8 by 2.0 meters; and

an effective inductance having an inductive reactance of not more than about 12 to 15 ohms.

2. The plasma chamber of claim 1 further comprising an effective resistance of not more than about 0.3 to 2.0 ohms.

3. The plasma chamber of claim 1 wherein the plasma chamber is adapted to process substrates used for flat panel displays.

4. The plasma chamber of claim 1 wherein the plasma chamber comprises:

a first chamber portion having an inner surface;

a second chamber portion coupled to the first chamber portion so as to define an inner chamber region;

a first electrode positioned a first distance from the first chamber portion;

a second electrode positioned between the first electrode and the second chamber portion so as to define a plasma region between the first and second electrodes; and

a conductive piece positioned between the first chamber portion and the first electrode and coupled to the first chamber portion so as to create a current path that reduces an effective inductance of the plasma chamber.

5. The plasma chamber of claim 4 wherein the conductive piece is approximately parallel to the first electrode and approximately the same length and width as the first electrode.

6. The plasma chamber of claim 4 wherein the conductive piece comprises aluminum.

7. The plasma chamber of claim 4 wherein the conductive piece is spaced about 0.5 to 2.0 inches from the first electrode.

8. The plasma chamber of claim 4 wherein the conductive piece is spaced about 1.5 to 1.75 inches from the first electrode.

9. The plasma chamber of claim 4 wherein the first electrode is an upper electrode.

10. The plasma chamber of claim 1 wherein the plasma chamber comprises:

a first chamber portion having an inner surface;

a first electrode positioned a first distance from the first chamber portion; and

a second electrode positioned between the first electrode and the second chamber portion so as to define a plasma region between the first and second electrodes;

wherein the first chamber portion has an increased thickness that creates a current path that reduces an effective inductance of the plasma chamber.

11. The plasma chamber of claim 10 wherein the inner surface of the first chamber portion is spaced about 0.5 to 2.0 inches from the first electrode.

12. The plasma chamber of claim 10 wherein the inner surface of the first chamber portion is spaced about 1.5 to 1.75 inches from the first electrode.

13. The plasma chamber of claim 10 wherein the first electrode is an upper electrode.

14. A method comprising:

providing a plasma chamber having:

a chamber size of at least about 1.8 by 2.0 meters; and

an effective inductance having an inductive reactance of not more than about 12 to 15 ohms; and

employing the plasma chamber to process substrates used for flat panel displays.

15. The method of claim 14 wherein the plasma chamber has an effective resistance of not more than about 0.3 to 2.0 ohms.

16. A plasma chamber comprising:

a first chamber portion having an inner surface;

a first electrode positioned a first distance from the first chamber portion;

17. The plasma chamber of claim 16 wherein the conductive piece is approximately parallel to the first electrode and approximately the same length and width as the first electrode.

18. The plasma chamber of claim 16 wherein the conductive piece comprises aluminum.

19. The plasma chamber of claim 16 wherein the conductive piece is spaced about 0.5 to 2.0 inches from the first electrode.

20. The plasma chamber of claim 16 wherein the conductive piece is spaced about 1.5 to 1.75 inches from the first electrode.

21. The plasma chamber of claim 16 wherein the first electrode is an upper electrode.

22. The plasma chamber of claim 16 wherein the plasma chamber has a chamber size of at least about 1.8 by 2.0 meters.

23. A plasma chamber comprising:

a first chamber portion having an inner surface;

24. The plasma chamber of claim 23 wherein the inner surface of the first chamber portion is spaced about 0.5 to 2.0 inches from the first electrode.

25. The plasma chamber of claim 23 wherein the inner surface of the first chamber portion is spaced about 1.5 to 1.75 inches from the first electrode.

26. The plasma chamber of claim 23 wherein the first electrode is an upper electrode.

27. The plasma chamber of claim 23 wherein the plasma chamber has a chamber size of at least about 1.8 by 2.0 meters.