CN114318259A

CN114318259A - Sputter deposition apparatus and method

Info

Publication number: CN114318259A
Application number: CN202111119888.7A
Authority: CN
Inventors: S.高特
Original assignee: Dyson Technology Ltd
Current assignee: Dyson Technology Ltd
Priority date: 2020-09-30
Filing date: 2021-09-24
Publication date: 2022-04-12
Also published as: GB2599392B; GB2599392A; GB202015460D0

Abstract

A sputter deposition apparatus for sputtering a sputter material from a sputter target onto a substrate. The sputter deposition apparatus includes a helical plasma source array including a plurality of helical plasma sources. Each helicon plasma source comprises a Radio Frequency (RF) antenna arranged to be driven by an electric current so as to generate a helicon wave propagating away from the antenna in a transmit direction and thereby generate a plasma in a plasma generation region.

Description

Sputter deposition apparatus and method

Technical Field

The present invention relates to a sputter deposition apparatus, and more particularly, to generation of plasma in a sputter deposition apparatus. The invention also relates to a method of sputter deposition.

Background

Deposition is a process by which a target material is deposited on a surface, such as a substrate. An example of deposition is thin film deposition, in which a thin layer (typically from about one nanometer or even a fraction of a nanometer to several micrometers or even tens of micrometers) is deposited on a substrate, such as a silicon wafer or web.

An example technique of thin film deposition is Physical Vapor Deposition (PVD), in which a target material in a condensed phase is vaporized to generate a vapor. The vapor is then condensed onto the substrate surface. An example of PVD is sputter deposition, in which particles are ejected from a sputtering target as a result of bombardment by energetic particles (e.g., ions). In an example of sputter deposition, a sputtering gas, such as an inert gas, e.g., argon, is introduced into a vacuum chamber at low pressure and the sputtering gas is ionized using energetic electrons to generate a plasma. Particles are ejected from the sputtering target by bombardment with ions of the plasma. The ejected particles may then be deposited on the substrate surface. Sputter deposition has an advantage over other thin film deposition methods (e.g., evaporation) in that the target material can be deposited without heating the target, which can in turn reduce or prevent thermal damage to the substrate.

Known sputter deposition techniques employ a magnetron in which a glow discharge, in combination with a magnetic field, causes an increase in plasma density in a circular region adjacent the sputter target. An increase in plasma density can result in an increase in deposition rate. However, the use of magnetrons results in sputtering targets having a circular "racetrack" shaped erosion profile, which limits the utilization of the sputtering target and can negatively impact the uniformity of the resulting deposition. It is desirable to provide uniform and/or efficient sputter deposition to allow for increased utility in industrial applications.

WO2011/131921 discloses a sputter deposition apparatus wherein the density is 10¹¹cm^-3Is generated separately from the sputtering target by an elongated gas plasma source. The plasma thus generated is magnetically guided and confined in the vicinity of the sputtering target. Such a remotely generated plasma arrangement may provide various advantages over a magnetron arrangement; for example, more uniform (less localized) sputtering of the sputtering target can be achieved (which can result in a significant increase in deposition rate), as well as the ability to operate and/or maintain the sputtering target under conditions unsuitable for generating a plasma.

In general, the higher the plasma density in a sputter deposition apparatus, the higher the deposition rate that can be obtained. (plasma density may also be referred to as electron density, or number of free electrons per unit volume). It is known that helical plasma sources have a higher ionization efficiency and can therefore produce higher plasma densities. In general, a helical plasma source can generate a plasma density higher than that generated using an Inductively Coupled Plasma (ICP) source. In ICP, the plasma can effectively shield itself from external oscillating fields, and can therefore only experience surface heating of the plasma within the thin layer. The helicon plasma source generates helicon waves that can propagate into the plasma, which can be excited to a greater depth by wave heating. It is known to use a helical plasma source to generate plasma in a sputter deposition apparatus. However, prior art helical plasma sources typically require a cylindrical source chamber, which is difficult to scale up for sputter deposition onto larger substrates. In particular, it is difficult to scale up such plasma sources while maintaining a uniform distribution of the plasma in the process chamber.

The present invention seeks to mitigate one or more of the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an improved sputter deposition apparatus and/or sputter deposition method.

Disclosure of Invention

According to a first aspect, the present invention provides a sputter deposition apparatus for sputtering sputter material from a sputter target onto a substrate, the sputter deposition apparatus comprising: a process chamber; a substrate assembly arranged to receive a substrate; a sputtering target assembly disposed to receive a sputtering target, the sputtering target assembly being spaced apart from the substrate assembly, the sputtering target assembly and the substrate assembly defining a deposition zone therebetween; an array of helicon plasma sources comprising a plurality of helicon plasma sources, each helicon plasma source comprising a Radio Frequency (RF) antenna arranged to be driven by an electrical current so as to generate helicon waves that propagate away from the antenna in a direction of emission and thereby generate plasma (e.g. in a plasma generation region).

Combining the output of multiple helical plasma sources may allow for the generation of a relatively large area of uniform dense plasma in a process chamber. By adjusting and optimizing the power, angle, and spacing between the helical plasma sources, uniformity may be improved and/or achieved. Using an array of relatively small helicon plasma sources to generate plasma, rather than scaling up a larger helicon plasma source, may provide advantages including: the proven and well understood plasma antenna design can be utilized with greater efficiency due to relatively small losses, prototyping of the design of a new sputter deposition apparatus is easier and cheaper, and the flexibility of the sputter deposition apparatus is improved, e.g. the helical plasma antenna can be rearranged to optimize plasma generation depending on the application and/or smaller substrates can be processed using only a subset of all helical plasma sources.

The plasma generated by the helical plasma source may have a plasma density of 10¹⁷m^-3Or higher plasma density. The plasma generated by the helical plasma source may have a range of 10¹⁷To 10¹⁹m^-3Plasma density in between. The sputter deposition apparatus can be configured such that, in use, the plasma density at the sputter target assembly (and, in use, at the sputter target) is 10¹⁷m^-3Or higher. Herein, has a 10¹⁷m^-3Or higher plasma density, may be referred to as a high density plasma.

The helical plasma sources of the array of helical plasma sources may be arranged to collectively produce a sheet of plasma. Preferably, the sheet is a high density plasma sheet. The plasma sheet may have a substantially uniform plasma density. The plasma sheet may extend into the deposition zone. The plasma sheet can extend over the sputtering target assembly. In use, the plasma sheet preferably extends over and contacts a sputter target received by the sputter target assembly. The plasma sheet may have a length, a width, and a thickness, wherein the length and the width are at least two times, at least three times, or at least four times the thickness.

The sputter deposition apparatus can be configured such that the plasma density is lower at the substrate assembly than at the sputtering target assembly. Thus, in use, the plasma density can be lower at the substrate than at the sputter target. For example, a plasma may be present at the substrate, but not a high density plasma. That is, the plasma density at the substrate assembly (and in use at the substrate) may be less than 10¹⁷m^-3. In a near vacuum environment of the process chamber, it may be difficult to cool the substrate. Thus, the substrate is heat sensitive and/or if the substrate is in contact withSuch an arrangement may be advantageous in situations where high density plasma contact may be damaged.

The helical plasma sources each include a cylindrical source chamber. The plasma may be at least partially generated in a cylindrical source chamber. The helical plasma sources may each include a single loop antenna, a multiple loop antenna, a helical antenna (e.g., a partial or full helical antenna), or a classic house type III antenna. In alternate embodiments, other antenna types may be used, for example, a spiral (i.e., stove top) type antenna may be used.

The array of helical plasma sources may be disposed inside the process chamber, that is, inside a chamber containing a process gas (e.g., argon). The sputter deposition apparatus may include a housing arranged to electrically isolate the antenna from a plasma generated in the plasma generation region. The enclosure may be gas tight, e.g. such that process gases cannot enter the enclosure. The interior of the housing may be at atmospheric pressure. The cylindrical source chamber may define an aperture into and/or through the housing.

In an alternative embodiment, the array of helical plasma sources is disposed outside the process chamber. The antenna may be disposed proximate to a wall of the process chamber such that the helicon wave generated by the antenna generates plasma in a plasma generation region inside the process chamber. The cylindrical source chamber of each helical source may be mounted to a wall of the process chamber, the interior of the source chamber being in fluid communication with the interior of the process chamber.

In an alternative embodiment, the array of helical plasma sources is disposed within the process chamber, but no such enclosure is provided. The antennas may have a coating, for example, a sintered ceramic coating, that electrically isolates each antenna from the plasma generated in the plasma generation region.

Each helical plasma source may be configured to generate a plasma plume, each plume overlapping an adjacent plume generated by an adjacent helical plasma source. Preferably, the helical plasma source is arranged to maximise the uniformity of plasma density produced across the array of helical plasma sources. For example, the helical plasma source may be arranged to maximize the uniformity of plasma density laterally across the plasma sheet.

The array of helical plasma sources may be elongate in a lengthwise direction. That is, the helical plasma sources constituting the helical plasma source array may be positioned in an arrangement having an elongated shape. The plasma sheet may extend laterally in a lengthwise direction (e.g., between two opposing lateral edges).

The helical plasma source array may include four or more, five or more, six or more, or ten or more helical plasma sources. The helical plasma sources may each have a diameter (e.g., measured transverse to the direction of emission) of one quarter or less, one fifth or less, one sixth or less, or one tenth or less of the length (e.g., in the lengthwise direction) of the array of helical plasma sources. That is, the length of the helical plasma source array may be at least four, five, six, or ten times the diameter of a single helical plasma source. The helical plasma sources may each have a diameter of 20cm or less, 15cm or less, 10cm or less, or 5cm or less.

The helical plasma sources may be arranged in a linear array (e.g., in which the helical plasma sources are arranged side-by-side in a straight line). The helical plasma sources may be arranged in a plurality of rows. For example, the helical plasma sources may be arranged in two linear rows. The rows may be vertically offset from each other (e.g., the rows may be above and below each other). The helical plasma sources in each row may be directly above and below each other, thereby forming a rectangular array. The helical plasma sources in each row may be laterally offset from each other, and the helical plasma sources may thus have a staggered arrangement.

The helical plasma sources may be arranged such that the emission directions of at least some (e.g. at least half, optionally all) of the helical plasma sources are parallel to each other. The helical plasma sources may be arranged such that the emission direction of some (e.g., at least half) of the helical plasma sources (e.g., plasma sources in the first row) is parallel to a first direction, and the emission direction of some (e.g., other) of the helical plasma sources (e.g., plasma sources in the second row) is parallel to a second direction different from the first direction. The first direction and the second direction may be convergent. That is, at least some of the helical plasma sources may have converging emission directions.

The helical plasma sources may be arranged on different (e.g., opposite) sides of the deposition zone. There may be a first plurality of helical plasma sources (e.g., arranged in a row) at a first side of the deposition zone and a second plurality of helical plasma sources (e.g., arranged in a row) at a second side of the deposition zone. The emission directions of the first and second plurality of helical plasma sources may both be directed towards the deposition zone. The helical plasma sources may be staggered such that the helical plasma sources on a first side of the deposition zone are laterally staggered from the helical plasma sources on a second side of the deposition zone. The plume of the helical plasma source on the first side may overlap with the plume of the helical plasma source on the second side (e.g., the lateral edges of the plumes may overlap). Such an arrangement may contribute to improving the uniformity of the plasma density.

The sputter deposition apparatus may be configured such that the current supplied to each antenna can be independently controlled. In an alternative embodiment, the antennas may be connected such that they are driven by the same current.

The sputter deposition apparatus may include one or more magnets (e.g., an emission magnet) configured to establish a magnetic field having a direction substantially parallel to the emission direction of each helical plasma source. The helicon wave may propagate along the magnetic field lines established by the transmitting magnet. One or more (e.g., a pair of) such magnets may be provided separately for each helical plasma source. That is, each helical plasma source may have its own magnet(s) associated with it. In other embodiments, there may be one or more (e.g., a pair of) such magnets that establish a magnetic field across multiple (e.g., all) of the helical plasma sources in the array of helical plasma sources. The (emitting) magnet may be a permanent magnet. The permanent magnets advantageously can be more easily provided in a smaller form factor. The (transmitting) magnet may be an electromagnet. The electromagnet may provide a magnetic field of controllable strength, which may help to manipulate and/or optimize the shape of the plasma so produced. At least some of the magnets may be disposed within a housing of the spiral plasma array.

In an embodiment, the transmitting magnets may be on the opposite side of the deposition area from the respective antenna. For example, each antenna may individually have a transmitting magnet associated therewith, wherein the transmitting magnet is disposed on an opposite side of the deposition area from the antenna.

The deposition zone may be remote from the plasma antenna assembly. The sputter deposition apparatus may include a confining arrangement including one or more magnets arranged to provide a confining magnetic field to confine the plasma generated by the helical plasma source to the deposition zone. A confining arrangement of magnets may be added as an emitting magnet, although it will be appreciated that the emitting magnet may contribute to the confining magnetic field that confines the plasma. At least some (e.g., at least one) of the restrictively arranged magnets may be disposed in the process chamber remote from the array of helical plasma sources. For example, at least some (e.g., at least one) of the magnets may be disposed at a distal side of the deposition zone relative to the array of helical plasma sources. The confinement arrangement may confine the (high density) plasma to a specific region in the process chamber where there are other regions in the process chamber that do not include the (high density) plasma due to the confining magnetic field.

The limiting arrangement can include one or more magnets configured to orient (e.g., bend) the magnetic field lines toward the sputtering target assembly and (when in use) the surface of the sputtering target. The magnetic field lines can open (i.e., become more separated) as they approach the sputter target.

The sputter deposition apparatus can be configured such that the distance between the spiral plasma array and the sputter target can be varied. For example, the sputter deposition apparatus can be configured such that the sputter target can be positioned at different distances from the helical plasma array within the process chamber. In an embodiment, the array of helical plasma sources may be moved towards and away from the deposition zone. As the distance from the array of helical plasma sources increases, the plasma density may decrease (e.g., decrease). Thus, this arrangement can provide a way to vary the plasma density at the sputtering target.

There can be a plurality of sputtering target assemblies. Each sputtering target assembly can be associated with a different deposition zone. In use, each sputtering target assembly need not receive the same sputtering material. In an embodiment, at least two sputtering target assemblies receive different sputtering materials.

There may be a plurality of helical plasmonic antenna arrays. Each helical plasma antenna array may be associated with a different sputtering target assembly and/or deposition zone.

The substrate assembly may be arranged to move the substrate within the process chamber (e.g., during a sputter deposition process). The substrate assembly may be arranged to guide the substrate along a curved path. The substrate assembly may include one or more rollers. One or more rollers may be arranged to convey the substrate through one or more deposition zones. One or more deposition zones can be defined between the roller and the sputtering target assembly. The substrate may be flexible, for example to allow it to be passed over one or more rollers. The substrate may be unwound from one roll and wound onto another roll. A sputter deposition apparatus comprising such a roller arrangement may be referred to as a roll-to-roll or reel-to-reel sputter deposition apparatus. The substrate may pass between intermediate rollers (which are, for example, between an unwind roller and a wind-up roller). One or more deposition zones can be defined between the intermediate roller and the sputtering target assembly.

A confining arrangement may be arranged to confine the plasma to a curved sheet. The curved sheet may extend partially around at least one roller (e.g., an intermediate roller). At least a portion of the confining magnetic field may be concentric with the at least one roller. There can be a plurality of sputtering target assemblies and/or deposition zones disposed circumferentially around at least one of the rollers.

The sputter deposition apparatus can further include a sputter target received by the sputter target assembly, and/or a substrate received by the substrate assembly.

According to a second aspect, the present invention provides a method of sputter deposition using a sputter deposition apparatus according to the first aspect of the invention, the method comprising the steps of: driving an antenna with an RF frequency current to propagate a helicon wave and generate a plasma in a plasma generation region; generating a sputtered material from one or more sputtering targets using a plasma; and depositing the sputtered material onto the substrate.

One or more sputtering targets can be positioned remote from the array of helicon plasma sources. The method may include the step of confining plasma from the array of helical plasma sources to the deposition zone using a confinement arrangement. In an alternative embodiment, there may be no restrictive arrangement and the plasma may diffuse and drift from the array of helical plasma sources to the sputtering target without being confined by and propagating to the restrictive magnetic field established by such restrictive arrangement.

The method may also include moving the substrate within the process chamber. The method may include rotating the roller to move the substrate through the deposition zone during sputtering. The method may further comprise unwinding the substrate from a first roll and winding the substrate around a second roll.

The antenna may be driven at a radio frequency between 1Mhz and 1Ghz, between 1Mhz and 100Mhz, or between 10Mhz and 40 Mhz. For example, the antenna may be driven at a radio frequency of 13.56 MHz.

According to a third aspect, the present invention provides a method of configuring a sputter deposition apparatus according to the first aspect of the invention, the method comprising the steps of: the position of each helical plasma source in the array of helical plasma sources is determined so as to provide, in use, a substantially uniform plasma density at the sputtering target. The method of the second aspect may additionally comprise the method of the third aspect.

According to a fourth aspect, the present invention provides an electronic device comprising a component comprising a layer of material deposited using the method of the second aspect.

It will of course be appreciated that features described in relation to one aspect of the invention may be incorporated into other aspects of the invention. For example, the method of the invention may incorporate any of the features described with reference to the apparatus of the invention, and vice versa.

Drawings

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which:

FIG. 1 shows a schematic cross-sectional side view of a sputter deposition apparatus according to a first embodiment of the invention;

FIG. 2 shows a schematic front view of a helical plasma source array of a sputter deposition apparatus according to a first embodiment of the invention;

fig. 3 shows a schematic cross-sectional plan view of a sputter deposition apparatus according to a first embodiment of the invention, with magnetic field lines shown;

FIG. 4 shows a schematic cross-sectional side view of a sputter deposition apparatus according to a second embodiment of the invention;

FIG. 5 shows a schematic cross-sectional side view of a sputter deposition apparatus according to a second embodiment of the invention, with magnetic field lines shown;

FIG. 6 shows a schematic bottom view of a sputter deposition apparatus according to a second embodiment of the invention, certain parts being omitted for clarity;

FIG. 7 shows a schematic bottom view of a sputter deposition apparatus according to a second embodiment of the invention, with certain parts omitted for clarity and magnetic field lines shown;

FIG. 8a shows a schematic front view of an alternative helical plasma source array of the sputter deposition apparatus according to the invention;

FIG. 8b shows a schematic cross-sectional side view of the helical plasma source array of FIG. 8 a;

FIG. 9a shows a schematic front view of a second alternative helical plasma source array of the sputter deposition apparatus according to the invention;

FIG. 9b shows a schematic cross-sectional side view of the helical plasma source array of FIG. 9 a; and is

FIG. 10 shows a schematic plan view of a third alternative helical plasma source array of the sputter deposition apparatus according to the invention;

Detailed Description

Fig. 1 shows a sputter deposition apparatus 100 according to a first embodiment of the present invention. The sputter deposition apparatus includes a process chamber 102. Disposed within the process chamber are a substrate assembly 106 and a sputtering target assembly 110. The substrate assembly 106 and the sputtering target assembly 110 are spaced apart, defining a deposition zone therebetween. The deposition zone is generally indicated by arrow 112. FIG. 1 shows a substrate 104 received by a substrate assembly 106, and a sputter target 108 received by a sputter target assembly 110. A process gas supply system 136 is provided for introducing one or more process gases (e.g., argon) or process gas mixtures into the process chamber 102.

A movable shutter assembly 114 is disposed in the path between the sputtering target 108 and the substrate 104. The movable shutter assembly 114 has an "open" position and a "closed" position. In the open position, the sputtered material ejected from the sputtering target 108 can coat the substrate 104. In the closed position, the sputtering target 108 can be sputtered without coating the substrate 104. In embodiments, the movable shutter assembly 114 may be removed or replaced with a set of fixed shutters that define the coating aperture under which the substrate assembly 106 translates to coat the substrate 104.

A helical plasma source array 116 is also disposed within the process chamber 102. The helical plasma source array 116 includes a plurality of individual helical plasma sources 117. Each helical source 117 includes a Radio Frequency (RF) antenna 118. Each antenna 118 is individually connected to an impedance matching network 120 and a signal generator 122. The signal generator 122 is configured to drive the antenna 118 at RF frequencies. The signal provided to each antenna may be independently controlled by an associated signal generator 122. In an alternative embodiment, all antennas 118 are coupled to the same impedance matching network 120 and signal generator 122 such that all antennas 118 are driven by the same current.

Each antenna 118 is a single loop antenna comprising a single closed loop of conductive material wrapped around a cylindrical source chamber 126. When driven by the signal generator 112, the antenna 118 generates a helicon wave that propagates away from the antenna 118 in a transmit direction 142. The emission direction 142 is parallel to the longitudinal axis of the source chamber 126 and orthogonal to the plane in which the loop of conductive antenna material is disposed. The helicon wave generated by the antenna 118 ionizes the process gas and generates a high density plasma 138 in a plasma generation region (generally indicated by arrow 140) within the cylindrical source cavity 126 and emanates from the cylindrical source cavity 126.

The antenna 118 is disposed in an enclosure 124, the enclosure 124 being hermetically sealed from the rest of the process chamber 102 and electrically isolating the antenna 118 from the high density plasma 138. In use, the interior of the housing 124 may be maintained at atmospheric pressure. The interior of each cylindrical source chamber is open to the process chamber 102.

Two

magnets

128, 130 are also provided in the process chamber 102. In this embodiment, the

magnets

128, 130 are electromagnets powered by a power source (not shown), which allows the strength of the magnetic field generated by each

magnet

128, 130 to be independently controlled. The first magnet 128 is an emitter magnet and is disposed on a side of the helical plasma source array 116 away from the deposition zone 112. The magnet 128 has an elongated annular shape and is configured to establish a local magnetic field that is oriented generally parallel to the cylindrical source chamber 126. When the antenna 118 is driven by the signal generator 120, the helicon wave is transmitted by the antenna 118 in a transmit direction 142 along the field lines established by the magnet 128.

The second magnet 130 forms a confining arrangement and is disposed on the opposite side of the deposition zone 112 from the helical plasma source array 116. The magnet 130 has an elongated geometry corresponding to the first magnet 128. The first and

second magnets

128, 130 together establish a magnetic field in the deposition zone 112 that is oriented across (i.e., parallel to) the surface of the substrate 104 and the sputtering target 108.

As shown in fig. 2 and 3, the helical plasma source array 116 is a linear array of nine helical plasma sources 117. The helical plasma sources 117 are in a coplanar arrangement and are equally spaced in the lengthwise direction (into the plane of the paper in fig. 1). The helical plasma sources 117 are also aligned such that the emission directions 142 are parallel to each other. The helical plasma sources 117 each have a diameter D. In this case, the diameter is defined by the diameter of the loop of the antenna 118. In an embodiment, the diameter is 5cm and the length of the source chamber 126 is 10 cm. Although the figures are schematic and not to scale, the longitudinal extent (L) (measured in the longitudinal direction) of the helical plasma source array 116 is at least nine times its thickness (i.e., at least nine times the diameter D). Thus, the helical plasma source array 116 as a whole has a shape elongated in the longitudinal direction.

The orientation of the array of helical plasma sources 116 is such that the emission direction of each helical plasma source 117 is directed towards the deposition zone 112. In use, the plasma generated by each helical plasma source 117 diffuses away from the plasma generation region 140 and towards the deposition region 112. The elongated shape of the helical plasma source array 116 means that the high density plasma 138 collectively generated by the helical plasma source 117 forms a high density plasma sheet that extends to the deposition region 112 and across the sputtering target 108. The magnetic field established by the

magnets

128, 130 confines the plasma in a sheet-like manner. In an embodiment, the high density plasma sheet is confined in a region closer to the sputtering target 108 than to the substrate 104 in order to reduce or prevent the high density plasma 138 from contacting the substrate 104.

As can be seen, the sheet of plasma 138 extends laterally in the lengthwise direction of the array of helical plasma sources 116 (that is, between its lateral edges (i.e., the edges that are not contiguous with the plasma generation region)). The helical plasma sources 117 are spaced such that the sheet of plasma 138 has a substantially uniform plasma density lengthwise between two opposing lateral edges of the sheet. Separately, the high-density plasma extends from each helical plasma source 117 to form a plume-shaped region 114 of the high-density plasma. In this embodiment, the helical plasma sources 117 are close enough together that adjacent plasma plumes 114 overlap one another.

Fig. 3 also shows some of the field lines of the magnetic field established by the

magnets

128, 130. As can be seen, the field lines extend from the helical plasma source array 116 to the deposition zone 112. The field lines within the deposition zone 112 are substantially parallel and the magnetic field is substantially uniform, which can promote uniform sputtering of the sputtering target 108.

In an alternative embodiment, the second magnet 130 is positioned above (or, in an alternative embodiment, inside) the base sputter target assembly 110 so as to establish a magnetic field directed toward the sputter target 108.

Fig. 4 shows a sputter deposition apparatus 200 according to a second embodiment of the present invention. The sputter deposition apparatus 200 is a roll-to-roll (also referred to as roll-to-roll) sputter deposition apparatus.

The sputter deposition apparatus 200 includes a process chamber similar to the first embodiment, however, for clarity, the walls of the process chamber are omitted in fig. 4 and 5. Within the process chamber is a substrate assembly 206 comprising a plurality of rollers including a first roller 246, a second roller 248, and an intermediate roller 250, the substrate web 204 being unwound from the first roller 246, the substrate web 204 being wound onto the second roller 248, and the substrate web 204 being conveyed between the first roller 246 and the second roller 248 in a curved path (C) around the intermediate roller 250.

Sputter target assembly 210 is disposed adjacent to but spaced apart from the surface of intermediate roller 250. Sputter target assembly 210 is provided with sputter target 208 suitable for plasma sputtering. A deposition zone 212 is defined between sputtering target assembly 210 and the surface of intermediate roller 250.

The helical plasma source array 216 is disposed at one side of the intermediate roller 250. The helical plasma source array 216 includes a housing 224 containing a plurality of helical plasma sources 217. The helical plasma source array 216 has the same structure as the helical plasma source array 116 of the first embodiment, and is oriented such that the lengthwise direction of the helical plasma source array 116 is parallel to the rotation axis of the intermediate roller 250.

The sputter deposition apparatus 200 also includes a plurality of

magnets

228, 230, 232 disposed in the process chamber. As with the first embodiment, the

magnets

228, 232 are electromagnets and have an elongated geometry that matches the helical plasma source array 116. One of the magnets 228 is a transmitting magnet disposed in the housing 224 and configured to establish a magnetic field local to each antenna 218 that is oriented generally parallel to the cylindrical source chamber 226. The remaining two

magnets

230, 232 form a limiting arrangement and are disposed on either side of the deposition zone 212.

As shown in fig. 5 and 7, the

magnets

228 and 232 together establish a magnetic field having field lines extending from the helical plasma source array 216 through the deposition zone 212. As such, the field lines circumferentially surround a portion of the circumference passing through the intermediate roller 250.

In use, the antennas 218 of the array of helicon plasma sources 216 are driven to emit helicon waves and generate plasma in a plasma generation region 240 remote from the deposition zone 212. The magnetic field confines and propagates the plasma 238 into a sheet that extends through the deposition zone 212. The sheet has a curved shape as it passes around the intermediate roller 250. As also shown in fig. 6, the sheet extends laterally in a direction parallel to the axis of rotation 252 of the intermediate roller 250. The rollers of the substrate assembly 206 rotate and transport the substrate 204 at a constant rate through a deposition zone 212 where the substrate 204 is coated with sputtered material ejected from a sputtering target 208.

In an alternative embodiment, the sputter deposition apparatus includes a plurality, e.g., three, sputter target assemblies circumferentially disposed about the intermediate roller. A deposition zone is defined between each sputtering target assembly and the surface of the intermediate roller. The plasma sheet is confined so as to pass through each deposition zone. In an embodiment, the sputtering target assemblies each receive a different sputtering material such that different layers of material are deposited onto the substrate web.

Fig. 8a and 8b show an alternative helical plasma source array 316 for a sputter deposition apparatus according to the invention. The helical plasma source array 316 includes twelve helical sources 317, each of which includes a multi-loop antenna 318 surrounding a cylindrical source chamber 326. As with the first embodiment, a helical plasma antenna 318 is disposed in the housing and there is an elongated electromagnet configured to establish a magnetic field parallel to the longitudinal axis of the source chamber 326.

The helical plasma sources 317 of the helical plasma source array 316 are arranged in two linear rows of six helical plasma sources 317 each, the two rows being vertically offset so that one row is above the other. The two rows are also laterally offset from each other such that the helical plasma sources 317 of the upper row are positioned between the helical plasma sources 317 of the lower row. In this manner, the helical plasma sources 316 have a staggered arrangement.

As can be seen most easily in fig. 8b, the emission directions 342 of the helical plasma sources 317 are parallel to each other, the emission directions 342 of the helical sources 317 of the upper row are in a first plane, and the emission directions 342 of the helical plasma sources 317 of the lower row are in a second plane that is lower than and parallel to the first plane. Such an arrangement may be used to increase the thickness of the plasma sheet, for example, compared to the linear helical plasma source array 116 of the first embodiment.

Fig. 9a and 9b show an alternative helical plasma source array 416 for a sputter deposition apparatus according to the invention. The helical plasma source array 416 includes eight helical plasma sources 417, each including a helical antenna 418 surrounding a cylindrical source chamber 426. As with the first embodiment, the antenna 418 is disposed in the housing 424.

Each helical plasma source 417 of the helical plasma source array 416 is provided with its own transmitting magnet 428. The launch magnet 428 is an axially magnetized permanent ring magnet (i.e., the opposite end faces of the ring have opposite polarities). Each transmitting magnet 428 is coaxial with the cylindrical source chamber 426 and is used to establish a magnetic field local to the antenna 418 that is oriented generally parallel to the longitudinal axis of the cylindrical transmitting chamber 426.

The helical plasma sources 417 of the helical plasma source array 416 are arranged in a rectangular array comprising two rows of four helical plasma sources 417 per row, the two rows being vertically offset so that one row is above the other. The two rows are laterally aligned such that the helical plasma sources 417 of the upper row are directly above the helical plasma sources 417 of the lower row.

As can be seen most easily in fig. 9b, the emission directions of the upper row of helical plasma sources 417 are angled downwards (in a first direction), while the emission directions of the lower row of helical plasma sources 417 are at right angles (in a second direction), so that the two emission directions converge and the high density plasma plumes 444 generated by the upper and lower helical plasma sources 417 overlap and converge. This arrangement may increase ionization and, therefore, plasma density in this overlapping and converging region.

It will be appreciated that the particular features of the helical

plasma source arrays

116, 216, 316, 416 described herein may be varied or interchanged. For example, the helical plasma source array 116 may be provided with permanent emission magnets, the helical plasma source array 316 may have two rows of helical plasma sources angled such that the directions of emission converge, the helical plasma source array 416 may use a single loop antenna, or the like.

FIG. 10 shows another alternative helical plasma source array 516 for a sputter deposition apparatus according to the present invention. The helical plasma source array 516 includes a plurality of

helical plasma sources

517a, 517b disposed on either side of the central deposition zone 512. The

helical plasma sources

517a, 517b are staggered such that the helical plasma source 517a on a first side of the deposition zone 512 is laterally offset from the helical plasma source 517b on the other side of the deposition zone 512. The plume of the helical plasma source 517a on the first side overlaps with the plume of the helical plasma 517b on the other side.

In the illustrated embodiment, the

helical plasma sources

517a, 517b are provided with their own launching magnets 528 on both sides of a cylindrical launching chamber 526. In alternative embodiments, one or more emitter magnets may be disposed on the opposite side of the deposition zone from the associated source chamber.

It will be appreciated that the precise configuration of the helical plasma source, in terms of the size of the individual sources, the antenna type, power, spatial distribution, number of sources, the type of emitter magnets and the angles therebetween, can be adjusted and optimized for each application and sputter deposition apparatus to increase the uniformity and/or density of the plasma within the deposition zone, and thus the rate and uniformity of sputter deposition, particularly for larger and very large substrates (e.g., those having dimensions on the order of meters). The use of multiple smaller helicon plasma sources, as opposed to one larger and higher power helicon plasma source, provides flexibility in this regard, which is not achievable with a single relatively larger helicon plasma source. In particular, the use of multiple smaller helical plasma sources may allow thinner sheets to be formed and may help control the uniformity in the direction across the web.

Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. The reader will also appreciate that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Further, it should be understood that such optional integers or features, while potentially beneficial in some embodiments of the invention, may not be desirable in other embodiments and therefore may not be present.

Claims

1. A sputter deposition apparatus for sputtering a sputter material from a sputter target onto a substrate, said sputter deposition apparatus comprising:

a process chamber;

a base assembly arranged to receive the base;

a sputter target assembly arranged to receive the sputter target, the sputter target assembly being spaced apart from the substrate assembly, the sputter target assembly and the substrate assembly defining a deposition zone therebetween;

an array of helicon plasma sources comprising a plurality of helicon plasma sources, each helicon plasma source comprising a Radio Frequency (RF) antenna arranged to be driven by an electric current so as to generate helicon waves propagating away from the antenna in a transmit direction and thereby generate a plasma.

2. The sputter deposition apparatus of claim 1, wherein the helical plasma sources of the array of helical plasma sources are arranged to collectively produce a sheet of plasma extending into the deposition zone.

3. The sputter deposition apparatus of claim 2, wherein the helical plasma source array is elongated in a lengthwise direction and the plasma sheet extends laterally in the lengthwise direction.

4. The sputter deposition apparatus of claim 1, wherein the array of helical plasma sources comprises four or more helical plasma sources.

5. The sputter deposition apparatus of claim 1, wherein each helical plasma source is configured to generate a plasma plume, each plume overlapping an adjacent plume.

6. The sputter deposition apparatus of claim 1, wherein the plasma density at the target assembly is higher than the plasma density at the substrate assembly.

7. The sputter deposition apparatus of claim 1, wherein the helical plasma source is arranged such that at least some of the emission directions are parallel to each other.

8. The sputter deposition apparatus of claim 1, wherein the helical plasma source is arranged such that at least some of the emission directions are convergent.

9. The sputter deposition apparatus of claim 1, wherein a first plurality of helical plasma sources is disposed on a first side of the deposition zone and a second plurality of helical plasma sources is disposed on an opposite second side of the deposition zone.

10. The sputter deposition apparatus of claim 1, wherein the current supplied to each antenna can be independently controlled.

11. The sputter deposition apparatus of claim 1, wherein the antennas are connected such that the antennas are driven by the same current.

12. The sputter deposition apparatus of claim 1, comprising one or more emitter magnets configured to establish a magnetic field having a direction substantially parallel to the emission direction of each helical plasma source, wherein the one or more emitter magnets are permanent magnets.

13. The sputter deposition apparatus of claim 1, wherein the sputter deposition apparatus is configured such that the distance between the helical plasma array and the sputter target can be varied in order to vary the plasma density at the sputter target.

14. The sputter deposition apparatus of claim 1, wherein the substrate assembly is arranged to move the substrate within the process chamber.

15. The sputter deposition apparatus of claim 14, wherein the substrate assembly comprises one or more rollers arranged to convey a flexible substrate through the deposition zone.

16. The sputter deposition apparatus of claim 1, wherein the deposition zone is remote from the plasma antenna assembly and the sputter deposition apparatus includes a confining arrangement including one or more magnets arranged to provide a confining magnetic field to confine the plasma generated by the helical plasma source to the deposition zone.

17. The sputter deposition apparatus of claim 16, wherein the confining arrangement is arranged to confine the plasma to a curved sheet.

18. The sputter deposition apparatus of claim 1, further comprising a sputter target received by said sputter target assembly, and a substrate received by said substrate assembly.

19. A method of sputter deposition using the sputter deposition equipment according to any of the preceding claims, the method comprising the steps of:

driving the antenna with an RF frequency current so as to propagate a helicon wave and generate a plasma in a plasma generation region;

generating sputtered material from one or more sputtering targets using the plasma; and is

Depositing the sputtered material onto the substrate.

20. A method of configuring the sputter deposition apparatus according to any one of claims 1 to 19, said method comprising the steps of: the position of each helical plasma source in the array of helical plasma sources is determined so as to provide, in use, a substantially uniform plasma density at the sputter target.