KR100809889B1 - Plasma chamber with externally excited torroidal plasma source - Google Patents

Abstract

A suture defining a vacuum chamber, a workpiece support in the suture that opposes the portion located above the suture, and a suture having at least first and second openings about the periphery of a generally opposite surface of the workpiece support, Plasma reactor for processing the workpiece. One or more cavity conduits are connected to the first and second openings. A closed toroidal path is provided through the conduit and extends between the first and second openings across the wafer surface. In order to provide the process gas in a toroidal path, a process gas supply is coupled inside the chamber. The coiled antenna is coupled to the RF power source, inductively coupled to the interior of the cavity conduit, and can maintain a plasma in the toroidal path.

Toroidal Plasma Source, Process Chamber

Description

Plasma chamber with externally excited toroidal plasma source {PLASMA CHAMBER WITH EXTERNALLY EXCITED TORROIDAL PLASMA SOURCE}

FIELD OF THE INVENTION The present invention relates to plasma reactors used to process process workpieces in the manufacture of devices such as microelectronic circuits, flat panel displays and the like, and more particularly, to plasma sources therefor.

In microelectronics, high density and miniaturization tendencies make the plasma processing of the device more difficult. For example, as the depth of the hole increases, the diameter of the contact hole decreases. During plasma enhanced etching of the dielectric film on the silicon wafer, the etching selectivity of the dielectric material for photoresist (e.g., silicon dioxide) does not interfere with the photoresist mask defining the hole, but at a depth of 10 to It should be satisfied with the etching process for etching the diameter of the contact hole which is 15 times. As recent trends for shorter wavelength light for more sophisticated photolithography require thinner photoresist layers, this task becomes more difficult, and therefore dielectric layer to photoresist etch selectivity must be increased than before. Such conditions are more easily met using processes with relatively low etch rates, such as dielectric etch processes using capacitively coupled plasma. The density of the capacitively coupled plasma is relatively smaller than the plasma density of the inductively coupled plasma, and the capacitively coupled plasma etch process exhibits excellent dielectric to photoresist etch selectivity. The problem with capacitively coupled processes is that they are very slow and therefore have relatively low productivity. Another problem arising in the etching process is the non-uniform plasma distribution.

In order to increase productivity or etch rate, high density plasma has been used. Typically, the high density plasma is an inductively coupled plasma. However, high density plasma dissociates the process precursor gas more quickly, forming high-plasma content of free fluore, a species that reduces etch selectivity for photoresist. To reduce this tendency, a fluorine-carbon process gas such as CF ₂ is used that dissociates into one or more polymer species, which accumulate on non-oxide containing surfaces such as fluorine containing etchant species and photoresist in the plasma. This easily increases the etch selectivity. To etch the dielectric material while the non-oxygen containing material (ie photoresist) is continuously covered by the polymer and protected from the etchant, the oxygen of the oxygen containing dielectric material promotes pyrolization of the polymer on the dielectric to Remove Increasing the contact opening depth and decreasing the photoresist thickness to accommodate more advanced devices has the problem of causing a high density plasma process that is susceptible to damaging the photoresist layer during dielectric etching. As the plasma density is increased to improve the etch rate, a large amount of polymer-containing plasma, such as a photoresist, may be used to increase the removal rate of the polymer from the oxygen-containing dielectric surface, particularly in confined areas such as the bottom of narrow contact openings. Should be used to protect them. As a result, the photoresist is significantly protected and when the contact opening reaches a predetermined depth, it increases the likelihood of the etching process that is hindered by polymer accumulation. Typically, the etch stop depth is below the depth of the contact opening where the device fails. The contact opening may provide a connection between the upper polysilicon conductor layer and the lower silicon conductor layer through the intermediate insulating silicon dioxide layer. For example, if the etch stop depth is less than or equal to the distance between the top silicon layer and the bottom silicon layer, a device failure occurs. In addition, a process window occurs to achieve a high density plasma without etch stops that narrow the actual or reliable application to be a more advanced device with contact openings in a ratio of 10: 1 or 15: 1.

Current preferred reactors have the etch rate of inductively coupled plasma reactors (with high density plasma) and the selectivity of capacitively coupled reactors. In a single apparatus, it was difficult to realize the advantages of the two type reactors.

The problem of having a high density inductively coupled plasma reactor, especially an overhead coiled antenna facing the wafer or workpiece, is that as the voltage applied to the coiled antenna is increased to enhance the etch rate, The wafer-to-ceiling gap must be large enough to absorb power into the plasma region on the wafer. This prevents the risk of damaging the device on the wafer due to the strong RF field. In addition, at a high level of RF power applied to an overhead coil type antenna, the wafer-to-sealing gap is relatively large, so the advantage of a small gap cannot be realized.

If the sealing is a semiconductor window for the RF field of an inductively coupled reactor or a conductive electrode of a capacitively coupled reactor, the advantage of a small wafer-to-sealing gap is that the sealing has a relatively small gap distance (i.e., 1 or Enhanced potential or ground reference across the face of the wafer at 2 inch dimensions).

Thus, for example, in addition to reactors with ion density and etch rate of inductively coupled reactors and selectivity of capacitively coupled reactors, wafer-to-sealing in addition to fundamental limitations such as, for example, plasma sheath thickness. It is desirable to have a reactor that does not have any conventional limitations on the gap length. It would also be desirable to have a reactor having selectivity for capacitively coupled reactors and etch rates for inductively coupled reactors that enhance ion density and etch rate without increasing the applied RF plasma source power.

The plasma reactor for processing the workpiece includes an enclosure, a workpiece support in the enclosure opposite the seal top, wherein the workpiece support and the top of the seal are generally over the diameter of the wafer support. The process area which extends in between is defined. Generally, the suture has at least a first opening and a second opening through opposite surfaces of the workpiece support. Providing a first toroidal path through the conduit and across the process region, wherein one or more hollow conduits outside the process region are connected to the first and second openings. do. The first coiled antenna, manufactured to receive RF power, is an inductively coupled reactor inside a common conduit conduit and can maintain plasma in a toroidal path.

1 is a diagram showing a first embodiment for maintaining an overhead toroidal plasma current path.

FIG. 2 is a side view of an embodiment corresponding to the embodiment of FIG. 1. FIG.

FIG. 3 is a graph showing the reaction of prefluorine concentration of plasma with wafer-to-sealing gap distance.

4 is a graph showing the response of the prefluorine concentration of the plasma according to the RF bias power applied to the workpiece.

5 is a graph showing the response of the prefluorine concentration of the plasma according to the RF source power applied to the coil-shaped antenna.

6 is a graph showing the reaction of the prefluorine concentration of the plasma with the pressure of the reaction chamber.

7 is a graph showing the reaction of the plasma prefluorine concentration with the partial pressure of an inert diluent gas such as argon.

8 is a graph showing the dissociation degree of the process gas according to the source power in the inductively coupled reactor and the reactor of the present invention.

9 is a diagram illustrating a modification of the embodiment of FIG. 1.

10 and 11 show a variant of the embodiment of FIG. 1 in which a closed magnetic core is used.

FIG. 12 shows another embodiment of the invention in which a toroidal plasma current path passes through the reaction chamber bottom.

FIG. 13 is a diagram showing a variation of the embodiment of FIG. 10 in which plasma source power is applied to a coil wound around a centrifugal closure magnetic core.

14 shows an embodiment for generating two parallel toroidal plasma currents.

FIG. 15 shows an embodiment for generating a plurality of independently controlled parallel toroidal plasma powers.

FIG. 16 is a diagram showing a variation of the embodiment of FIG. 15 in which parallel toroidal plasma currents enter through the vertical sidewalls rather than the seal.

17A is a diagram illustrating an embodiment in which a pair of mutually orthogonal toroidal plasma currents are maintained over the surface of a workpiece.

FIG. 17B is a diagram illustrating the use of a plurality of radial vanes in the embodiment of FIG. 17A.

18 and 19 show an embodiment of the present invention which is an optical belt extending over an optical path suitable for processing a substrate having a large toroidal plasma current.

20 shows a variation of the embodiment of FIG. 18 where the outside of the toroidal plasma current path is limited.

FIG. 21 illustrates a variation of the embodiment of FIG. 18 using the axial position of a cylindrical magnetic core capable of adjusting the ion density distribution across the wafer.

FIG. 22 shows a variation of FIG. 21 in which a pair of windings are wound around a pair of groups of cylindrical magnetic cores.

FIG. 23 shows a variant of FIG. 22 in which a single common winding is wound around a two group core.

24 and 25 show an embodiment in which a large wafer is held with a pair of mutually orthogonal toroidal plasma currents that are optical belts suitable for processing.

FIG. 26 illustrates a variation of the embodiment of FIG. 25 in which a magnetic core is used to enhance inductive coupling.

FIG. 27 illustrates a variation of the embodiment of FIG. 24 in which an orthogonal plasma belt introduces the reaction chamber through vertical sidewalls rather than horizontal sealing.

FIG. 28A illustrates a variation of the embodiment of FIG. 24 generating a rotating toroidal plasma current.

FIG. 28B illustrates a variation of the embodiment of FIG. 28A with a magnetic core.

29 is a diagram showing the best embodiment of the present invention in which a continuous plenum is provided to surround the toroidal plasma current.

30 is a top cross-sectional view corresponding to FIG. 29.

31A and 31B are front and side cross-sectional views corresponding to FIG. 30.

FIG. 32 illustrates a variation of the embodiment of FIG. 29 using three independent drive RF coils under opposing continuous piping at 120 degree intervals.

FIG. 33 illustrates a variation of the embodiment of FIG. 32 in which two RF coils are driven at 120 degree intervals to provide azimuth rotational plasma.

FIG. 34 shows a variation of the embodiment of FIG. 33 with the corresponding edges extending horizontally below the tubing at angles symmetrically distributed, with the RF coil wound around the vertical outer edge of each magnetic core.

FIG. 35 shows a variation of the embodiment of FIG. 17 with narrow conduits of mutual throttling cavities as in the embodiment of FIG. 20.

FIG. 36 illustrates a variation of the embodiment of FIG. 24 using a pair of magnetic cores 3610 and 3620 wound around each winding 3630 and 3640 for the connection of each RF power source.

FIG. 37 shows an embodiment corresponding to the embodiment of FIG. 35 with three entities instead of two in a total of six re-entrants to the chamber.

FIG. 38 shows an embodiment corresponding to the embodiment of FIG. 38 with three entities instead of two in a total of six re-entrants to the chamber.

FIG. 39 is a view showing an embodiment corresponding to the embodiment of FIG. 35 to which external conduits are coupled in the common pipe 3910.

40 is a diagram showing an embodiment corresponding to the embodiment of FIG. 36 to which external conduits are coupled in the common pipe 4010.

FIG. 41 is a view showing an embodiment corresponding to the embodiment of FIG. 37 to which external conduits are coupled in the common pipe 4110.

FIG. 42 is a diagram showing an embodiment corresponding to the embodiment of FIG. 38 in which external conduits are coupled in the common pipe 4210.

FIG. 43 is a view showing an embodiment corresponding to the embodiment of FIG. 17 to which external conduits are coupled in the common pipe 4310.

Overview of plasma reaction chamber:

Referring to FIG. 1, the plasma reaction chamber 100 and the sealing 110 surrounded by the cylindrical sidewall 105 provide a wafer pedestal 115 for supporting a semiconductor wafer or workpiece 120. Process gas supply 125 supplies process gas to chamber 100 through gas inlet nozzles 130a-130d extending through sidewall 105. Vacuum pump 135 controls the pressure in chamber 100 and typically maintains pressure below 0.5 mT (millitorr). Half-toroid cavities, tube sutures or conduits 150 extend over the seal 110 in a semicircle. Although extending out of the seal 110, the conduit 150 is part of the reactor and forms the wall of the chamber. Internally, the conduits share the same vacuum atmosphere that is exhausted somewhere in the reactor. In fact, the vacuum pump 135, as shown in FIG. 1, may not be coupled with the conduit 150, but instead is coupled to the bottom of the main portion of the chamber. The conduit 150 has one open end 150a sealed around the first opening 155 in the reactor sealing 110 and the other end sealed around the second opening 160 in the reactor sealing 110. 150b). Typically, two openings or ports 155, 160 are located on opposite surfaces of the wafer support base 115. The common conduit 150 is a re-entrant where the flow path exits the main part of the chamber at one opening and re-enter at the other opening. In this specification, the conduit 150 is hollow and provided with a closed path portion such that the plasma can flow to complete the entire path by flowing over the entire process area located on the wafer support base 115. It can be described as toroidal. Despite using Atorroidal @, like the path or cross-sectional shape of the conduit 150, the path's trajectory may be circular or non-circular, or may be square, rectangular or other shapes that are regular or irregular.

The outer conduit 150 is formed of a relatively thin conductor, such as a sheet metal, but is strong enough to withstand the vacuum in the chamber. An insulating gap 152 for inhibiting eddy currents in the sheet metal of the cavity conduit 150 (and encouraging coupling of the RF induced field into the conduit 150) crosses the cavity conduit 150. By passing and extending, it dissociates into two tubular parts. The gap 152 is vacuumed tightly by filling with a ring 154 of insulating material, such as ceramic, instead of a sheet metal skin. A second insulating gap 153 can be provided so that a portion of the conduit 153 is not electrically connected. The bias RF generator 162 passes RF bias power through the impedance matching element 164 and applies it to the wafer support 115 and the wafer 120.

In addition, the hollow conduity 150 may be formed of a non-conductive material instead of the conductive sheet metal. For example, the non-conductive material can be ceramic. In another embodiment, no gap 152 or 153 is needed.

An antenna 170, such as a winding or coil 165 disposed on one side of the conduit 150 of the cavity and wound around an axis parallel to the axis of symmetry of the half toroidal tube, is an impedance matching element for the RF source 180. Is connected via 175. The antenna 170 further includes a second winding 185 disposed on the opposite surface of the common conduit 150 and wound in the same direction as the first winding 165 so that the magnetic field from both windings can be structurally added. can do.

The cavity conduit 150 is filled with process gases from the chamber 100. In addition, the dissociation process gas supply 190 can supply process gases directly to the conduit 150 through the gas inlet 195. The RF field in the tube in the conduit 150 of the outer cavity ionizes the gases to produce a plasma. The RF field induced by the circular coiled antenna 170 allows the plasma formed in the tube 150 to reach through the region between the wafer 120 and the sealing 110 so that the conduit of the half-toroid cavity Complete the toroidal path with hollow conduity 150. As used herein, Atorroidal @ relates to the closed and solid properties of a path, but not to or limiting the shape or trajectory of the cross section, which may be circular, non-circular, square, or the like. The plasma circulates through a complete toroidal path or region, which is considered a closed plasma circuit. The toroid region extends across the diameter of the wafer 120 and in some embodiments has a sufficient width on the plane of the wafer to cover the entire wafer surface.

Since the RF inductive field from the coiled antenna 170 itself comprises a closed magnetic field (as all magnetic fields do), it induces plasma current along the closed toroidal path described below. Power from the RF inductive field is generally absorbed at all locations along the closed path such that plasma ions are all generated along the path. The ratio of RF power absorption and plasma ion generation varies between different locations along the closed path depending on many factors. However, although the current density may vary, the current is generally uniform along the closed path length. This current alternates at the frequency of the RF signal applied to the antenna 170. However, because the current induced by the RF magnetic field is closed, the current must be conserved around the circuit of the closed path so that the amount of current flowing in any part of the closed path is generally the same as in any other part of the path. As will be explained below, this fact is of great advantage in the present invention.

The closed toroidal path through which the plasma current flows is limited by the plasma sheath formed at the various conductive surfaces that limit the path. These conductive surfaces include the sheet metal of the conduit 150, the wafer (or wafer support base, or both the wafer and the wafer support base) and the sealing located on the wafer. The plasma sheath formed on this conductive surface becomes charge depletion regions resulting from charge imbalance due to the small mobility of negative ions and the larger mass of cations. Such plasma sheaths have an electric field perpendicular to the local surface lying on the sheath. Thus, the RF plasma current passing through the process zone or process zone overlying the wafer is limited by the surface of the seal facing the wafer and by two electric fields perpendicular to the surface of the wafer opposite the gas distribution plate, Pass between these electric fields. The thickness of the sheath (with RF bias applied to the workpiece or other electrode) is larger where the electric field is focused on a small area, such as a wafer, and more at other locations covering the sealing and large adjacent chamber wall surfaces. small. Thus, the plasma sheath placed on the wafer is much thicker. The electric fields of the wafer and sealing / gas distribution plate sheaths are usually parallel to each other and perpendicular to the direction in which the RF plasma current flows in the process area.

When RF power is first applied to the coiled antenna 170, a discharge occurs across the gap 152 to ignite a capacitively coupled plasma from the gases in the conduit 150 of the cavity. Thereafter, as the plasma current through the cavity conduit 150 increases, the inductive coupling of the RF field becomes more prevalent, so that the plasma becomes an inductively coupled plasma. The plasma may also be initiated by other means, such as an RF bias applied to the workpiece support or other electrode.

To avoid edge effects around the wafer, the ports 150, 160 are dissociated by a distance that exceeds the diameter of the wafer. For example, for a 12 inch diameter wafer, the ports 150, 160 are spaced about 16 to 22 inches apart. For an 8 inch diameter wafer, the ports 150 and 160 are spaced about 10 to 16 inches apart.

Advantages of the invention:

An important advantage is that power from the RF inductive field is absorbed through a relatively long closed toroidal path (relative to the gap length between the wafer and reactor sealing), so that the RF power absorption is distributed over a large area. . As a result, RF fields in the vicinity of the wafer-sealing gap (i.e., the process region 121 as shown in FIG. 2, not to be confused with the insulating gap 152) are relatively low, so that the RF fields Damage of the device from the device and the like can be reduced. In contrast, in previously inductively coupled reactors, all RF power is absorbed within the wafer-sealing gap, largely focused in that area. In addition, this fact often limits the ability to narrow the wafer-sealing gap (to obtain other advantages) or requires greater focusing of the absorption of RF power in the area of the wafer. Thus, the present invention overcomes the long-standing limitations in the art. This aspect enhances process performance by reducing the residence time of the reactant gases through a dramatic reduction in volume in the process area overlying the wafer as described herein.

A related and even more important advantage is that the plasma density at the wafer surface can be increased dramatically (which increases efficiency) without increasing the RF power applied to the coiled antenna 170. This is accomplished by reducing the cross-sectional area of the toroidal path in the vicinity of the wafer 120 relative to the substrate surface and the rest of the toroidal path. Only by limiting the toroidal path of plasma current close to the wafer, the density of the plasma close to the wafer surface is increased proportionally. This is because the plasma current of the toroidal path through the cavity conduit 150 is at least approximately equal to the plasma current through the base-to-sealing (wafer-sealing) gap.

An important difference from the prior art is not only the RF field away from the workpiece, the ion density at the wafer surface can be increased without increasing the RF field, as well as the plasma ion density, the applied RF field, or the plasma. Both the density and the applied RF field can be increased without increasing the minimum wafer-sealing gap length. Previously, such an increase in plasma density required that the wafer-sealing gap avoids strong fields at the wafer surface. In contrast, in the present invention, enhanced plasma density is achieved without any increase in the wafer-to-sealing gap needing to avoid an incidental increase in RF magnetic fields at the wafer surface. This is because the RF field is applied away from the wafer and does not need to be increased to realize an increase in plasma density at the wafer surface. As a result, the gap between wafer-sealings can be reduced to the fundamental limit at which many advantages can be achieved. For example, if the sealing surface on the wafer is conductive, reducing the wafer-to-sealing gap improves the electrical or grounding reference provided by the conductive sealing surface. The basic limitation on the minimum length of the wafer-sealing gap is the sum of the thicknesses of the plasma sheaths on the wafer surface and the sealing surface.

Another advantage of the present invention is that since the RF inductive field is applied along the entire toroidal path of plasma current (as described above, absorption is distributed), most other inductively powered Unlike the reactors, the sealing 110 of the chamber does not need to function as a window for the inductive field, and thus can be formed of any desired material with high conductivity and such as a thick metal, as described below, for example. It may include a conductive gas distribution plate. As a result, the seal 110 readily provides a reliable potential or ground reference for the entire plane of the substrate or wafer 120.

Increasing the plasma ion density:

One way to achieve higher plasma density near the wafer surface by reducing the plasma path cross-sectional area for the wafer is to reduce the wafer-sealing gap length. As shown in FIG. 2, this is achieved by simply reducing the height of the seal or introducing a conductive gas distribution plate or shower head on the wafer. The gas distribution showerhead 210 of FIG. 2 consists of a gas distribution tubing 220 that is connected to the gas supply 125 and communicates with the process area on the wafer 120 through a plurality of gas nozzle openings 230. The advantage of the conductive showerhead 210 has two sides: First, by its close position to the wafer, it increases the plasma current density in the vicinity by limiting the plasma path on the wafer surface. Second, it provides a uniform potential reference or ground plane close to or against the entire wafer surface.

Preferably, to avoid becoming arcuate across the openings 230, each opening 230 is relatively small in order of millimeters (preferably hole diameter is about 0.5 mm). The spacing between adjacent openings is in units of several millimeters.

Because the plasma sheath is formed around a portion of the showerhead surface contained within the plasma, the conductive showerhead 210 limits the plasma current path rather than providing a short circuit through itself. Since the sheath has a larger impedance between the wafer 120 and the showerhead 210, all plasma currents flow around the conductive showerhead 210.

It is not necessary to use a showerhead (eg, showerhead 210) to limit the path of the toroidal plasma current, or near the process area overlying the wafer. Path constraints, and the resulting increase in plasma ion density in the process region, can be achieved without showerhead 210 by similarly reducing the wafer-to-sealing height. If the showerhead 210 is removed in this manner, process gases can be supplied into the chamber by conventional gas inlet nozzles (not shown in the figure).

One advantage of the showerhead 210 is that different mixtures of active and inert process gas ratios are at different radii 230, for example to finely adjust the uniformity of the plasma effect on the photoresist. Can be introduced via Thus, while a larger proportion of the inert gas to the active gas is supplied to the opening 230 located outside of the central radius, a larger proportion of the active gas to the inert gas is applied to the openings 230 within the central radius. Can be supplied.

As described below, another way in which the toroidal plasma current path can be limited in the process area over which the wafer is placed (to increase the plasma ion density for the wafer) is an RF bias applied to the wafer support base. Increasing the power increases the thickness of the plasma sheath on the wafer. As described above, since the plasma current for the process region is defined between the plasma sheath at the wafer surface and the plasma sheath at the sealing (or showerhead) surface, increasing the plasma sheath thickness at the wafer surface is a process region. The cross section of the portion of the toroidal plasma current in it is inevitably reduced. Thus, as described in more detail later in this specification, as the RF bias power on the wafer support base is increased, the plasma ion density near the wafer surface is likewise increased.

High etch selectivity at high etch rates:

The present invention solves the problem of poor etch selectivity, which often occurs with high density plasma. The reactors of FIGS. 1 and 2 have etch selectivity between silicon dioxide-photoresist as high as the capacitively coupled plasma reactor (about 7: 1), while inductively coupled plasma at high density by providing a high etch rate. Access to the reactor. The reason for this result is that the reactor structure of FIGS. 1 and 2 reduces the degree of dissociation of the active process gas, which is usually fluorocarbon gas, to reduce the incidence of prefluorine in the plasma region of the wafer 120. It was thought that. Thus, the ratio of free fluorine in the plasma to other species dissociated from fluorocarbons is preferably reduced. Such other species include protective, carbon-rich polymer precursor species that are formed in the plasma from a fluorocarbon process gas and disposed on the photoresist as a protective polymer coating. They include less activated etch solution species such as CF and CF ₂ that are formed in the plasma from a carbon fluoride process gas. Free fluorine tends to attack the photoresist and the protective polymer coating formed thereon as strongly as it attacks silicon dioxide, thus reducing the oxygen-photoresist etch selectivity. On the other hand, less active etch types such as CF and CF ₂ tend to be more slowly attacking the photoresist and the protective polymer coating formed thereon, providing superior etch selectivity.

By reducing the residence time of the active gas in the plasma, a reduction in dissociation of the plasma species to prefluorine is achieved in the present invention. This means that more complex species initially dissociated in the plasma from carbon fluoride process gases such as CF and CF ₂ eventually dissociate themselves into simpler species containing prefluorine to this final dissociation stage depending on the residence time of the gas in the plasma. Because. As used herein, the term "residecy time" or "residence time" is generally present in the process region where process gas molecules and species dissociated from the molecules are located on the workpiece or wafer. This time or period of time corresponds to the processing zone of the molecule, its output, or both the molecule and its output from the initial input of the molecule into the process region along the toroidal closed path described above. The time taken to pass out of the process area extending through.

As described above, the present invention enhances the etching selectivity by reducing the residence time in the process region of the fluorocarbon process gas. The reduction in residence time is achieved by limiting the plasma volume between the wafer 120 and the sealing 110.

 Reduction in the wafer-sealing gap or volume has certain advantageous effects. First, it increases the plasma density for the wafer and enhances the etch rate. Second, the residence time decreases with increasing volume. As described above, in the present invention, unlike conventional inductively coupled reactors, the RF source power is not installed in the vessel of the process region located on the wafer, but rather the power installation is a total toroidal type of plasma current. Since it is distributed along the closed path, volume reduction is possible. Thereafter, the wafer-sealing gap may be smaller than the skin depth of the RF inductive field and, in fact, may be small enough to significantly reduce the residence time of the active gases introduced into the process area, which is an important advantage. do.

There are two ways to reduce the plasma path cross-sectional area and thus to reduce the volume for the wafer 120. One is to reduce the wafer-showerhead gap distance. The other is to increase the plasma sheath thickness for the wafer by increasing the bias RF power applied to the wafer base 115 by the RF bias power generator 162 as briefly described above. Both methods result in a decrease in the prefluorine content (and the resulting increase in dielectric-photoresist etch selectivity) near the wafer 120 as observed using optical emission spectroscopy (OES) technology. do.

There are three further methods of the present invention for reducing the free fluorine content to improve etch selectivity. One method is to introduce a nonchemically active diluent gas, such as argon, into the plasma. Preferably, argon gas is introduced outside and above the process region by direct injection from the second process gas supply 190 into the conduit 150 of the cavity, while chemically active process gases (carbon fluoride gases) Only through this showerhead 210 enters the chamber. Because of these advantageous configurations, argon ions, neutrals, and excited neutrals propagate through the process region across the wafer surface within the toroidal path plasma current to introduce newly introduced activity (eg, carbon fluoride Dilute gases to effectively reduce the residence time for the wafer. Another way to reduce the plasma free fluorine content is to reduce the chamber pressure. Another method is to reduce the RF source power applied to the coiled antenna 170.

3 is a graph showing the trend observed in the present invention, as the pre-fluorine content of the plasma decreases as the gap between wafer-shower heads decreases. 4 is a graph showing that the plasma prefluorine content is reduced by reducing the plasma bias power applied to the wafer base 115. 5 is a graph showing that the plasma prefluorine content is reduced by reducing the RF source power applied to the coiled antenna 170. 6 is a graph showing that the prefluorine content is reduced by reducing the chamber pressure. FIG. 7 is a graph showing that the plasma prefluorine content is reduced by increasing the diluent (argon gas) flow rate into the tubular suture 150. The graphs of FIGS. 3-7 merely show the trend of plasma operation inferred from many OES observations and do not represent actual data.

Wide process window of the present invention:

Preferably, the chamber pressure is lower than 0.5T and may be as low as 1mT. The process gas entering the chamber may be C ₄ F ₈ at a flow rate of about 15 cc / m with 150 cc / m of argon through the water distribution showerhead, and the chamber pressure is maintained at about 20 mT. In addition, the argon gas flow rate can be increased to 650 cc / m and the chamber pressure can be increased to 60 mT. Antenna 170 may be excited at about 500 W RF power at 13 MHz. The gap between the wafer and showerhead can be between 0.3 inches and 2 inches of liquid. The bias RF power applied to the wafer base may be 13 MHz at 2000W. You can choose a different frequency. The source power applied to the coiled antenna 170 may be as low as 50KHz or as high as several times or more of 13MHz. The same holds true for the bias power applied to the wafer substrate.

The process window of the reactor of FIGS. 1 and 2 is much wider than the process window of a conventional inductively coupled reactor. This is shown in the graph of FIG. 8, which shows the specific neutral flux of prefluorine as a function of RF source power for the conventional inductive reactor and the reactors of FIGS. 1 and 2. In a conventional inductively coupled reactor, FIG. 8 shows that when the source power exceeds between 50 and 100 watts, the specific flux of prefluorine begins to increase rapidly. In contrast, the reactor of FIGS. 1 and 2 can accommodate source power levels approaching 1000W before the specific flux of prefluorine rapidly increases. Thus, the source power process window of the present invention has significant advantages with orders of magnitude wider than those of conventional inductively coupled reactors.

Two advantages of the present invention:

By shortening the toroidal plasma current path near the wafer or workpiece, two independent advantages are created without any significant tradoff of other performance criteria: (1) Plasma density across the wafer is arbitrary Is increased without requiring an increase in the plasma source power of (2) and, as described above, the etching selectivity of the photoresist or other materials is increased. In conventional plasma reactors, it was impractical because it was not possible to increase the plasma ion density by the same step of increasing the etch selectivity. Therefore, two advantages realized with the toroidal plasma source of the present invention are greatly shown from the prior art.

Other Preferred Embodiments:

FIG. 9 illustrates one modification of the embodiment of FIG. 1 in which the side antenna 170 is replaced by a smaller antenna 910 that fits within the void space between the sealing 110 and the conduit 150 in the cavity. An embodiment is shown. Preferably, antenna 910 is a single coil winding in the center of cavity conduit 150.

10 and 11 illustrate how the embodiment of FIG. 1 can be enhanced by the addition of a magnetically closed transmissive core 1015 extending through the space between the sealing 110 and the conduit 150 of the cavity. Indicates whether there is. Core 1015 improves inductive coupling from antenna 170 to plasma inside cavity conduit 150.

Impedance matching can be accomplished by using secondary winding 1120 around core 1015 connected across tuning capacitor 1130 instead of impedance matching circuit 175. The capacitance of the tuning capacitor 1130 is selected to resonate the secondary winding at the frequency of the RF power source 180. In the fixed tuning capacitor 1130, dynamic impedance matching can be provided by frequency tuning, forward power servoing, or both frequency tuning and forward power servoing.

FIG. 12 shows an embodiment of the present invention in which a common tube seal 1250 extends around the bottom of the reactor and is connected to the interior of the chamber by a pair of openings 1260, 1265 of the lower floor of the chamber. . The coiled antenna 1270 follows the side toroidal path provided by the cavity tube seal 1250 in the manner of the embodiment of FIG. 1. 12 shows a vacuum pump 135 connected to the bottom of the main chamber, but the conduit 1250 at the bottom may instead be connected.

FIG. 13 shows an embodiment of a modification of the embodiment of FIGS. 10 and 11, in which the antenna 170 can be replaced with an inductive winding 1320 surrounding the top of the core 1015. Preferably, winding 1320 surrounds a portion of core 1015 over conduit 150 (rather than under conduit 150). However, the windings 1320 may surround any portion of the core 1015.

FIG. 14 shows the tube seal 1450 of the second cavity running in parallel with the conduit 150 of the first cavity and providing a toroidal path parallel to the second toroidal plasma current. An embodiment of extension of the concept is shown. The tube seal 1450 connects with the interior of the chamber at each of its ends through respective openings of the seal 110. The magnetic core 1470 passes through the coiled antenna 170 and extends below the two tube seals 150 and 1450.

FIG. 15 illustrates an embodiment of an extension of the concept of FIG. 14, wherein the parallel tube seals 150a, 150b, 150c, 150d arranged in parallel provide multiple toroidal plasma current paths through the reaction chamber. Indicates. In the embodiment of FIG. 15, the plasma ion density is controlled by the individual cavity tube sutures 150a-1 through each of the individual coiled antennas 170a-170d, each driven by independent RF power sources 180a-180d. 150d) controlled independently from each other. Individual cylindrical opening cores 1520a through 1520d may be inserted individually into respective coiled antennas 170a through 170d. In this embodiment, the related center to edge ion density distributions can be adjusted by individually adjusting the power levels of the individual RF power sources 180a through 180d.

FIG. 16 shows an embodiment of a modification of the embodiment of FIG. 15, in which the arrangement of tube seals 150a-150d extends through the sidewall of the reactor rather than through the seal 110. Another alternative embodiment shown in FIG. 16 uses a single common magnetic coder 1470 having an antenna 170 adjacent to and surrounding the tube sutures 150a-150d so that a single RF source can be used for the tube sutures ( Excitation of the plasma in both 150a to 150d).

FIG. 17A is excited by respective coiled antennas 170-1 and 170-2, and a pair of orthogonal tube sutures 150-1 and 150-2 extending through respective ports in sealing 110. Indicates. Separate cores 1015-1 and 1015-2 are in respective coiled antennas 170-1 and 170-2. This embodiment creates two mutually orthogonal toroidal plasma current paths throughout the wafer 120 to increase uniformity. The two orthogonal toroidal or closed paths are individually and independently powered as shown, but intersect with the process area overlying the wafer and otherwise do not interact. In order to ensure separate control of the plasma source power applied to each of the orthogonal paths, the frequencies of the respective RF generators 180a and 180b of FIG. 17 are different, so that the operation of the impedance matching circuits 175a and 175b is dissociated. do. For example, the RF generator 180a may generate an 11 MHz RF signal, while the RF generator 180b may generate a 12 MHz RF signal. Optionally, independent operation may be achieved by offsetting the phases of the two RF generators 180a and 180b.

FIG. 17B shows how radial vanes 18 are used to guide the toroidal plasma currents of each of the two conduits 150-1 and 150-2 through the processing region over the wafer support. Radial vanes 181 between the openings of each conduit near the side of the chamber extend to the edge of the wafer support. Since the radial vanes 181 prevent the conversion of plasma from one toroidal path to another, the two plasma paths only intersect within the processing area above the wafer support.

Embodiments suitable for large diameter wafers:

In addition to recent industry trends towards smaller device sizes and higher device densities, another trend relates to larger wafer diameters. For example, 12 inch diameter wafers are currently in production, and perhaps larger diameter wafers will come forward. The advantage is higher throughput because of the large number of integrated circuit units per wafer. A disadvantage is that in plasma processing, it is very difficult to keep the plasma uniform across a large diameter wafer. The following embodiments of the present invention are particularly adapted to provide a uniform plasma ion density distribution over the entire surface of a large diameter wafer, such as a 12-inch diameter wafer.                 

 18 and 19 show the tube seal 180 of the cavity, which is a wide flat rectangular version 1850 of the cavity conduit 150 of FIG. 1 including an insulating gap 1852. This version produces a wide plasma "belt" that is well suited to uniformly apply large diameter wafers, such as 12-inch diameter wafers or workpieces. The width W of the tube seal of the seal 110 and the pair of openings 1860, 1862 preferably exceeds the wafer by at least about 5%. For example, when the wafer diameter is 10 inches, the width W of the rectangular tube seal 1850 and the openings 1860, 1862 is about 11 inches. 20 shows a modified version 1850 of the rectangular tube seal 1850 of FIGS. 18 and 19 with the portion 1864 of the outer tube seal 1850 contracted. However, the non-contracted version of FIGS. 18 and 19 is preferred.

20 further illustrates the selective use of the focusing magnets 1870 to transition between the contracted and non-contracted portions of the suture 1850. The focusing magnets 1870 facilitate better movement of the plasma between the contracted and non-contracted portions of the suture 1850, in particular the contracted portion 1864 and the non-contracted portion of the tube seal 1850. When the magnet moves in accordance with the transition between, it encourages the diffusion of the plasma more evenly.

FIG. 21 shows how multiple cylindrical magnetic cores 2110 can be inserted through the outer region 2120 restricted by the tube seal 1850. Cylindrical cores 2110 are generally parallel to the axis of symmetry of the tube seal 1850. FIG. 22 shows the outer region 2120 surrounded by the tube seal 1850 with the fully extended cores 2110 replaced by a pair of cores 2210, 2220 shortened at each half of the outer region 2120. One embodiment of the change of the embodiment of FIG. 21 is shown. The side coils 165, 186 are replaced by a pair of coil windings 2230, 2240 surrounding each core pair 2210, 2220. In this embodiment, the displacement D between the core pairs 2210 and 2220 is changed to adjust the ion density near the wafer center to the ion density around the wafer. The wider displacement D reduces the inductive coupling near the wafer center, thus reducing the plasma ion density at the wafer center. Thus, additional control elements can be provided to accurately adjust the spatially distributed ion density along the wafer surface. 23 replaces the individual windings 2230, 2240 with a single center winding 2310 centered in the core pairs 2210, 2220.

24 and 25 show embodiments for further improving the uniformity of the plasma ion density distribution across the wafer surface. In the embodiment of FIGS. 24 and 25, two toroidal plasma current paths that traverse one another and are preferably perpendicular to each other are established. This is accomplished by providing a tube seal 2420 of a second wide rectangular cavity extending laterally and preferably orthogonally to the first tube seal 1850. The second tube seal 2420 is connected to the interior of the chamber through a pair of openings 2430 and 2440 through the seal 110 and includes an insulation gap 2452. The pair of side coil windings 2450, 2460 along the sides of the second tube seal 2420 maintain a plasma and is driven by a second RF power supply 2470 through an impedance matching circuit 2480. . As shown in FIG. 24, the two orthogonal plasma currents are consistent across the wafer surface, providing more uniform plasma coverage across the wafer surface. In particular, this embodiment may be advantageously used to handle large wafer diameters of 10 inches or more.

As with the embodiment of FIG. 17, the embodiment of FIG. 24 creates two mutually orthogonal toroidal plasma current paths across the wafer 120 to increase uniformity. The two orthogonal toroidal or closed paths dissociate and are independently powered as shown, but intersect with the process area overlying the wafer, otherwise they do not interact or otherwise switch or spread with each other. In order to ensure separate control of the plasma source power applied to each of the orthogonal paths, the frequency of each of the RF generators 180, 2470 in FIG. 24 is different, so that the operation of the impedance match circuits 175, 2480 is dissociated. do. For example, RF generator 180 may generate an 11 MHz RF signal, while RF generator 2470 may generate an RF signal of 12 MHz. Optionally, independent operation can be achieved by offsetting the phases of the two RF generators 180, 2470.

FIG. 26 illustrates a variation of the embodiment of FIG. 18 in which a modified rectangular suture 2650 comprising an insulating gap 2658 is connected to the interior of the chamber through the chamber sidewall 105 rather than through the seal 110. One embodiment. To this end, rectangular suture 2650 is a horizontal top 2652, each extending from the lower end of each of one of the legs 2654 extending downward to each opening 2670, 2680 of sidewall 105, the It has a pair of legs 2654 extending downward at each end of the upper portion 2652, and a pair of legs 2656 extending horizontally inward.

FIG. 27 shows how a second rectangular tube seal 2710 including an insulating gap 2528 can be added to the embodiment of FIG. 26, wherein the second tube seal 2710 is a rectangular tube seal Same as the rectangular tube seal 2650 of FIG. 26, except that the 2650, 2710 are orthogonal to (or at least cross over) each other. The second rectangular tube seal includes an opening 2720 and is connected to the interior of the chamber through respective openings through the side wall 105. As with the embodiment of FIG. 25, the tube seals 2650 and 2710 produce a coincident orthogonal toroidal plasma current across the wafer surface to provide good uniformity over a wide wafer diameter. Plasma source power is applied inside the tube seals through each pair of side coil windings 165, 185, 2450, and 2460.

FIG. 28A shows a pair of mutually orthogonal internal coils 2820, where the side coils 165, 185, 2450, 2460 are located in an outer region 2860 surrounded by two rectangular tube seals 2650, 2710. 2840) can be replaced (or added). Each of the coils 2820, 2840 generates a toroidal plasma current at the corresponding one of the rectangular tube seals 2650, 2710. Coils 2820 and 2840 may be driven completely independently at different frequencies or at the same frequency for the same or different phases. That is, they can be driven at the same frequency, but due to the phase difference (ie, 90 degrees), the combined toroidal plasma current can be cycled to the source power frequency. In this case, the coils 2820, 2840 are driven by the sine and cosine components of the common signal generator 2880, respectively, as shown in FIG. 28A. The advantage is that the plasma current path rotates azimuthally across the wafer surface at a rotational frequency above the plasma ion frequency, so that non-uniformity is more than prior art methods such as MERIE reactors where rotation is done at a much lower frequency. Is suppressed.

Next, referring to FIG. 28B, the radiation adjustment of the plasma ion density is generally a pair of cylindrical magnetic cores 2892, 2894 that can move along the axis towards or away from each other within the coil 2820 and It can be provided by installing a pair of cylindrical magnetic cores 2896, 2898 that can be moved along the axis towards or away from each other in the coil 2840. In the case where each pair of cores move toward each other, the inductive coupling near the center of each of the orthogonal plasma currents increases with respect to the edge of the current, thus generally increasing the plasma density at the wafer center. Thus, the plasma ion density from center to edge can be controlled by moving the cores 2892, 2894, 2896, 2898.

29 shows an alternative implementation of the present invention, in which two tube seals 2650 and 2710 are merged together into a single seal 2910 extended by 360 degrees around the central axis of the reactor constituting a single plenum. It shows form. In the embodiment of FIG. 29, the tubing 2910 has a half-dome bottom wall 2920 and a half-dome top wall 2930 that generally coincide with the bottom wall 2920. Thus, piping 2910 is a space between upper and lower half-dome walls 2920 and 2930. The insulating gap 2921 extends around the upper dome wall 2920, the insulating gap 2929 extends around the lower dome wall 2930, or the insulating gap 2921 extends around the upper dome wall 2920. And the insulating gap 2929 can extend around the lower dome wall 2930. Tubing 2910 is connected to the interior of the chamber through an annular opening 2925 in seal 110 that extends 360 degrees around the axis of symmetry of the chamber.

Tubing 2910 completely surrounds area 2950 above sealing 110. In the embodiment of FIG. 29, the plasma source power is connected with the interior of the piping 2910 by a pair of mutually orthogonal coils 2960, 2965. Coils 2960 and 2965 are accessed through vertical conduits 2980 passing through the center of tubing 2910. Preferably, the coils 2960 and 2965 are quadrature driven as in the embodiment of FIG. 28 to circulate the toroidal plasma current at an azimuth angle (ie, plasma current circulation in the plane of the wafer). The rotation frequency is the frequency of the applied RF power. Optionally, the coils 2960 and 2965 can be driven by different frequencies individually. 30 is a top view of the embodiment of FIG. 29. 31A and 31B are front and side views respectively corresponding to FIG. 30.

The pair of mutually orthogonal coils 2960, 2965 can be replaced by any number n of coils individually driven by winding axes disposed 360 / n degrees apart. For example, FIG. 32 shows that two coils 2960, 2965 are driven by three RF power sources 3240, 3250, 3260 through respective impedance match circuits 3321, 3351, 3261, and 120 degrees. The case is replaced by three coils 3210, 3220, 3230 with winding axes arranged at intervals. In order to generate a rotating toroidal plasma current, the three windings 3210, 3220, 3230 are driven in 120 degree phase from the common power source 3310 as shown in FIG. The embodiments of FIGS. 32 and 33 are preferred over the embodiment of FIG. 29 with only two coils, because the mutual coupling between the coils is made larger around it rather than by the vertical conduit 2980. to be.

FIG. 34 shows that three coils are outside of the sealed region 2950, but the inductances are connected to the sealed region 2950 by respective vertical magnetic cores 3410 extending through the conduit 2980. An embodiment is shown. Each core 3410 has one end extending over lead 2980, each of which coils 3210, 3220, 3230 are damaged. The bottom of each core is inside the sealed area 2950 and has a vertical leg. The horizontal legs of the three cores 3410 are oriented at 120 degree intervals to provide an inductive coupling to the interior of the tubing 229, similar to the coupling provided by the three coils inside the sealed region of FIG. 32.

The advantage of the flat rectangular tube sutures of the embodiments of FIGS. 18-28 is that, due to the wide width and relatively small height of the tube sutures, the plasma belt allows the toroidal plasma current to more easily cover the entire surface of a large diameter wafer. To make it wider and thinner. The entire tube seal need not be provided with maximum width. Instead, as disclosed with reference to FIG. 20, the outermost tube seal is necked down furthest from the chamber. In this case, at the transition corner between the wide portion 1801 and the narrow portion 1852, the plasma current is excited at the narrow portion 1852 and scattered throughout the entire width of the wide portion 1851. It is desirable to provide a magnet 1870. Next, if it is desired to maximize the plasma ion density on the wafer surface, it is preferable to make the cross-sectional area of the narrow portion 1852 at least as large as the cross-sectional area of the wide portion 1831. For example, the wide portion 1881 may have a height smaller than its width, while the narrow portion 1852 may be a passage that is approximately equal in height and width.

Hereinafter, another embodiment having an air-core coil (for example, a coil without a magnetic core) in place of the magnetic core may be adopted, and an open-magnetic-path (Arod @ type core) shown in the accompanying drawings. Or closed-self-cored. Also, the various embodiments described herein, having two or more toroidal paths driven at different RF frequencies, may instead be driven at the same frequency, and at the same or different phases.

FIG. 35 is a view showing an embodiment of the embodiment of FIG. 17 in which the conduits of the cavities crossing each other are narrow as in the embodiment of FIG. 20.

FIG. 36 illustrates an aspect of the embodiment of FIG. 24 using a pair of magnetic cores 3610 and 3620 wound around each winding 3630 and 3640 for the connection of each RF power source.

FIG. 37 illustrates an embodiment corresponding to the embodiment of FIG. 35 with three entities in place of two re-entrant conduits at a total of six re-entrant ports for the chamber. Having a plurality of symmetrically disposed conduits and two or more re-entrant ports is advantageous for process wafers of 300 mm diameter or more.                 

FIG. 38 shows an embodiment corresponding to the embodiment of FIG. 38 with three instead of two reentrant conduits at a total of six reentrant ports for the chamber.

FIG. 39 shows an embodiment corresponding to the embodiment of FIG. 35 to which external conduits are connected in a common pipe 3910.

40 is a diagram illustrating an embodiment corresponding to the embodiment of FIG. 36 in which external conduits are connected in the common pipe 4010.

FIG. 41 is a view showing an embodiment corresponding to the embodiment of FIG. 37 in which external conduits are connected in the common pipe 4110.

FIG. 42 is a diagram showing an embodiment corresponding to the embodiment of FIG. 38 in which external conduits are connected in the common pipe 4210.

FIG. 43 is a view showing an embodiment corresponding to the embodiment of FIG. 17 in which external conduits are connected in the common pipe 4310.

Advantage of the present invention

The reactor of the present invention may have many opportunities to increase etch selectivity without sacrificing other performance characteristics such as etch rate. For example, the formation of toroidal plasma power in the vicinity of the wafer not only improves the etching selectivity, but can also increase the etching rate by increasing the plasma ion density. In the prior art reactors, the etch selectivity was not increased by the same mechanism of increasing the etch rate or plasma ion density on the workpiece.

Improving etch selectivity by forming a toroidal plasma current around the wafer or workpiece can be accomplished in one of a plurality of methods of the present invention. One method is to reduce the base-sealing height or the wafer-sealing height. Another method is to introduce a gas distribution plate or showerhead onto the wafer, which compresses the path of the toroidal plasma ion current. Another method is to increase the RF bias power applied to the wafer or workpiece. Combinations of one or another of the methods for improving etch selectivity can be selected by those skilled in the art to practice the invention.

In the present invention, the etching selectivity can be further improved by locally injecting the reactive process gas while injecting an inert diluent gas (eg argon) from a distance (eg, into a conduit or tubing). This is preferably done by providing a gas distribution plate or showerhead directly above or opposite the workpiece support, so as to exclusively (or at least primarily) inject the reactive process gas into the showerhead. At the same time, diluent gas is injected into the conduit well spaced from the process area on the wafer or workpiece. Thus, the toroidal plasma current not only becomes a source of plasma ions for reactive ion etching of the material on the wafer, but also undergoes a plasma-induced dissociation process at the point where an undesirable amount of free florine is formed. It is an agent to spread away reactive process gas species and plasma-dissociation products prior to implementation. Reducing the residence time of reactive process gas species has a significant advantage of improving etch selectivity over photoresist and other materials.

The present invention provides high flexibility in the application of RF plasma source power to a toroidal plasma current. As mentioned above, power is typically coupled by a toroidal plasma current and an antenna. In many embodiments, the antenna is primarily plumbed with external conduits around or next to it. For example, the coiled antenna may extend along a conduit or pipe. However, in other embodiments, the antenna is limited to the area sealed between the conduit or tubing and the main reactor seal (eg, sealing). In the latter case, the antenna may be considered "bottom" rather than by the conduit side. Greater flexibility can be provided by embodiments having a magnetic core (or cores) extending through the sealed region (between the conduit and the main chamber seal) and having an extension beyond the sealed region. If present, the antenna may wrap around the core extension. In this embodiment, the antenna is inductively coupled through the magnetic core, so there is no need to be close to the toroidal plasma current in the conduit. In one such embodiment, a closed magnetic core is employed and the antenna wraps around the core portion furthest from the toroidal plasma current or conduit. Thus, the antenna may be located at any location, such as a location entirely remote from the plasma chamber by being remotely coupled with the toroidal current through the magnetic core.

Finally, the present invention provides a uniform plasma application on the surface of very large diameter wafers or workpieces. In one embodiment, the toroidal plasma current is performed by shaping as a wide plasma belt provided with a width that exceeds the width of the wafer. In another embodiment, the uniformity of plasma ion density across the wafer surface is achieved by providing two or more transverse or orthogonal toroidal plasma currents that intersect within the process region on the wafer. The toroidal plasma currents flow at 360 / n in the direction of mutual offset from each other. Each toroidal plasma current can be shaped into a wide belt of plasma covering a very wide diameter wafer. One of each toroidal plasma current may be powered by an antenna of dissociation coil type, aligned along the direction of one toroidal plasma current. In one preferred embodiment, uniformity can be improved by applying RF signals of different phases to each of the coiled antennas so that the toroidal plasma current rotates in the process region located on the wafer. In this preferred embodiment, the optimal configuration is for the toroidal plasma current to flow in a circular continuous tubing through the main chamber portion through a circular continuous annular opening in the seal or sidewall. The latter feature is that the entire toroidal plasma current rotates in azimuth in a continuous manner.

While the invention has been described in detail with reference to preferred embodiments, it will be understood that changes and modifications can be made without departing from the spirit and scope of the invention.

Claims (19)

A plasma chamber defining an interior atmosphere that is evacuated for processing a substrate, Substrate support; A gas distribution plate having an opening portion spaced apart from the substrate support and configured to flow a process gas into an atmosphere within the chamber proximate the substrate support, wherein a substrate processing region is defined between the gas distribution plate and the substrate support Gas distribution plate; And An interior having an interior sharing the interior atmosphere and having respective ends open to the substrate processing region on opposite sides of the gas distribution plate, The conduit of the cavity is configured to receive radiation by the RF field of the process gas therein to maintain a plasma in a path extending around the interior of the cavity of the cavity within the chamber interior and across the substrate process area. , Plasma chamber. The method of claim 1, The path is a re-entrant path. The method of claim 1, The path is toroidal. The method of claim 1, A plasma current circulates around the path. The method of claim 1, And the cross sectional area of the conduit of the cavity substantially exceeds the cross sectional area of the substrate processing region. The method of claim 1, And the ion density of the plasma is substantially uniform across the substrate support. The method of claim 1, The inductive field lines of the plasma extend from one of the conduit ends of the cavity to another over the substrate processing region. The method of claim 7, wherein The field lines are generally parallel. The method of claim 8, The intensity of the electric field of the electric field line is uniformly distributed over the substrate plasma process region. The method of claim 1, The cavity conduit includes an insulating gap generally intermediate between each of the ends to prevent a continuous conductive path from appearing between the ends. The method of claim 1, The conduit of the cavity has a outer diameter greater than or equal to the diameter of the substrate. The method of claim 1, Wherein each end of the cavity conduit has a transverse dimension that is at least as large as the substrate support. The method of claim 1, Further comprising an RF power applicator. The method of claim 13, And the RF power applicator comprises an RF inductive source. The method of claim 14, The RF inductive source is proximate the conduit of the cavity. The method of claim 1, And a bias RF power source coupled to the substrate support. The method of claim 1, And a gas inlet to the cavity conduit. The method of claim 17, The gas inlet is configured to allow diluent gas to flow and the gas distribution plate is configured to flow to a reactive process gas. The method of claim 1, Wherein the gas distribution plate is configured to allow different mixtures of inert and reactive process gases to flow in different radial directions.

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