Patent Description:
A sputtering chamber is used to sputter deposit material onto a substrate in the fabrication of integrated circuits and displays. Typically, the sputtering chamber comprises an enclosure around a sputtering target facing a substrate support, a process zone into which a process gas is introduced, a gas energizer to energize the process gas, and an exhaust port to exhaust and control the pressure of the process gas in the chamber. The sputtering target is bombarded by energetic ions formed in the energized gas causing material to be knocked off the sputtering target and deposited as a film on the substrate. The sputtered material can be a metal, such as for example aluminum, copper, tungsten, titanium, cobalt, nickel or tantalum; or a metal compound, such as for example, tantalum nitride, tungsten nitride or titanium nitride.

In certain sputtering processes, a magnetic field generator provides a shaped magnetic field about the sputtering surface of the sputtering target to improve sputtering properties and the sputtering surface of the sputtering target. For example, in magnetron sputtering, a set of rotatable magnets rotate behind the sputtering targets to produce a magnetic field about the front surface of the sputtering target. The rotating magnetic field provides improved sputtering by controlling the rate of sputtering across the sputtering target.

A cooling system passes heat transfer fluid through a housing surrounding the rotatable magnets to cool the magnets and the underlying sputtering target. However, conventional cooling systems often fail to remove sufficiently high levels of heat from the sputtering target and/or fail to provide spatially uniform heat removal from the sputtering target. As a result, hotter regions of the sputtering target are often sputtered at higher sputtering rates than adjacent regions, resulting in uneven sputtering across the surface of the sputtering target. Uneven target sputtering in combination with a rotating magnetic field can cause a sputtering target to develop a sputtering surface having erosion grooves and microcracks that extend downward from the erosion grooves can also form. The localized microcracks which occur at the erosion grooves can result in the ejection of sputtered particles during the sputtering process, which then deposit on the substrate to reduce yields. Sputtered particles that land on chamber components can also flake off at a later time due to thermal stresses arising from heating and cooling cycles. <CIT> discloses a sputtering chamber having a sputtering target comprising a backing plate and a sputtering plate. The backing plate comprises a backside surface having a plurality of concentric circular grooves and a plurality of arcuate channels which intersect the circular grooves. The sputtering target can be positioned abutting a heat exchanger housing which holds heat transfer fluid and a plurality of rotatable magnets. <CIT> discloses a cathode sputtering assembly including a sputter target welded to a corresponding backing member, where the target and backing member are adapted for insertion into a sputtering system. The target has a reduced diameter portion profiled for receipt within a counterbored upper section of the backing member. The target has a beveled surface above the reduced diameter section, and the backing member has an upper tapered edge, where the interface between the sputtering target and the backing member cooperate to define a V-groove. A chamber may be defined between the target and the backing member for flow of cooling water therethrough.

Thus it is desirable to have a sputtering target capable of being more efficiently, and more uniformly, cooled by a target cooling system. It is also desirable for the sputtering target to exhibit reduced localized cracking from thermal stresses.

Implementations of the present disclosure relate to a sputtering target for a sputtering chamber according to claim <NUM> used to process a substrate. The sputtering target comprises a sputtering plate with a backside surface having radially inner, middle and outer regions and an annular-shaped backing plate mounted to the sputtering plate. The backside surface has a plurality of circular grooves which are spaced apart from one another and at least one arcuate channel, or linear channels, cutting through the circular grooves and extending from the radially inner region to the radially outer region of the sputtering plate. The annular-shaped backing plate defines an open annulus exposing the backside surface of the sputtering plate. The sputtering target further includes the other features of claim <NUM>. Advantageous embodiments are subject-matter of the dependent claims.

In another implementation, a sputtering chamber as defined in claim <NUM> is provided. The sputtering chamber comprises a sputtering target according to claim <NUM> mounted in the sputtering chamber, a substrate support facing the sputtering target, a gas distributor to introduce a gas into the sputtering chamber, a gas energizer to energize the gas to form a plasma to sputter the sputtering target and a gas exhaust port to exhaust gas from the sputtering chamber.

Further described is a magnetron sputtering assembly comprising (a) a heat exchanger housing capable of holding heat transfer fluid about a plurality of rotatable magnets, (b) a sputtering target abutting the housing such that the heat transfer fluid contacts a backside surface of the sputtering target, and (c) a sputtering plate mounted on the front surface of the backing plate. The sputtering target comprises a backing plate having the backside surface, the backside surface including radially inner, middle and outer regions, wherein the radially middle region has a plurality of concentric circular grooves located at the backside surface and a plurality of concentric circular grooves located at the radially middle region of the backside surface, and a plurality of arcuate or linear channels extending from the radially inner region to the radially outer region of the backside surface. At least one of the backing plate and the sputtering plate comprise a material selected from Al0.5Cu, Al1.0Si, Al0.5Cu1.0Si, pure aluminum, copper, chrome, titanium, tungsten, molybdenum, cobalt, tantalum, Li-P-O-N, germanium, GeS<NUM>, silicon, SiO<NUM>, quartz, combinations thereof.

So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to implementations, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical implementations of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective implementations.

It is contemplated that elements disclosed in one implementation may be beneficially used in other implementations without specific recitation.

Implementations of the present disclosure relate to a sputtering target for a sputtering chamber used to process a substrate. Extraction of process chamber heat from sputtering targets is crucial to avoid uneven sputtering across the surface of the sputtering target. Normally, sputtering targets are cooled by having the backside (non-chamber side) exposed to cooling fluids (e.g., DI water) which is housed in the magnetron cavity. Given the spacing of the magnetron at ~<NUM> behind the sputtering target and with the magnetron spinning at ~60RPM (depending on magnetron design) there may be only a thin layer of water in contact with the backside of the sputtering target. This thin layer of water is being spun out centrifugally away from the center of the sputtering target which leads to overheating of the center area of the sputtering target which will degrade sputtered film performance. In some implementations, grooves are added to the backside of the sputtering target to allow deeper water films to be present and to use the centrifugal action of the magnetron to flush heated water out of the center to be replaced with cooler water.

Certain implementations described herein can also be applied to rectangular or other shaped targets with groove profiles designed to be appropriate for those shapes. Certain implementations described herein have the advantage of greatly increased cooling for the active parts of a sputter target. This increased cooling can then be utilized to allow far larger power densities in the process chambers for improvements in productivity, deposition rate, and deposition properties. Further, the implementations described herein may be used to cool any thermally conductive plate where heat is applied to one side and a coolant fluid is applied to the opposite side.

In certain implementations, the materials of both the backing plate and the sputtering target deposition materials are different. In certain implementations, the backing material of the sputtering material can be any appropriate metal such as aluminum and aluminum alloys (e.g., <NUM>, <NUM>, <NUM>%Al/<NUM>%Cu), copper, OFE copper, copper alloys (copper/chrome alloys, copper/zinc alloys, copper/tin alloys) or other thermally conductive metals. In certain implementations, the backing plate may be flat or dished.

Other, exemplary materials for at least one of the backing plate and the sputtering plate comprise materials selected from Al0.5Cu (wt. %) alloy, Al1.0Si(wt. %) alloy, A!<NUM>. 5Cu1.0Si(wt. %) alloy, pure aluminum, copper, chrome, titanium, tungsten, molybdenum, cobalt, tantalum, Li-P-O-N, germanium, GeS<NUM>, silicon, SiO<NUM>, quartz, combinations thereof and alloys thereof.

An exemplary implementation of a sputtering target <NUM> that can be used in a sputtering process chamber (e.g., process chamber <NUM>) to deposit sputtered material on a substrate (e.g., substrate <NUM>) with reduced erosion of grooves and microcracking, is shown in <FIG>. Referring to <FIG>, in one implementation, the sputtering target <NUM> comprises a backing plate <NUM> and a sputtering plate <NUM>. The sputtering plate <NUM> and the backing plate <NUM> can be a monolith comprising a single structure made from the same high-purity material and that serves as both a backing plate and a sputtering plate or they may be separate structures that are bonded together to form a sputtering target.

The sputtering plate <NUM> comprises a central cylindrical mesa <NUM> that serves as a sputtering surface <NUM>, a backside surface <NUM> opposing the sputtering surface <NUM>, a back surface <NUM> opposite the sputtering surface <NUM>, an outer peripheral wall <NUM> and an inner peripheral wall <NUM>. The outer peripheral wall <NUM> and the inner peripheral wall <NUM> may be cylindrical and both may be inclined slightly. The outer peripheral wall <NUM> extends from the sputtering surface <NUM> to the back surface <NUM>. The inner peripheral wall <NUM> extends from the backside surface <NUM> to the back surface <NUM>. As shown in <FIG>, a recess <NUM> is formed between the backside surface <NUM> and the inner peripheral wall <NUM>. The recess <NUM> exposes the backside surface <NUM> of the sputtering plate <NUM>.

The sputtering surface <NUM> has a top plane <NUM> that is maintained parallel to the plane of a substrate <NUM> during use of the sputtering target <NUM> in a chamber <NUM>. The sputtering plate <NUM> is made from a metal or metal compound. For example, the sputtering plate <NUM> can be composed of, for example, at least one of aluminum, copper, cobalt, nickel, tantalum, titanium, tungsten and alloys thereof. The sputtering plate <NUM> can also be a metal compound, such as for example, tantalum nitride, tungsten nitride or titanium nitride. In one implementation, the sputtering plate <NUM> comprises titanium at a high purity level, for example, at least about <NUM>%, or even at least about <NUM>%. Additional metal and metal compounds for the sputtering plate <NUM> are disclosed in Table I.

In one implementation, the sputtering target <NUM> comprises the backside surface <NUM> that opposes the sputtering surface <NUM>, and which has a pattern of circular grooves <NUM> (or 150a and 150b) and intersecting arcuate channels <NUM> (or 154a and 154b). The circular grooves <NUM> may extend from a radially inner region <NUM> of the sputtering plate <NUM> to a radially outer region <NUM> of the sputtering plate <NUM>. The circular grooves <NUM> may be positioned in a radially middle region <NUM> formed between the radially inner region <NUM> and the radially outer region <NUM>. The circular grooves <NUM> may have a radiused cross-section. The intersecting arcuate channels <NUM> cut through the circular grooves <NUM> at angles ranging from <NUM> to <NUM> degrees relative to the localized horizontal tangent to the circular groove <NUM> at the point of intersection. In some implementations, the arcuate channels <NUM> are spaced apart from one another by an angle of from about <NUM> to about <NUM> degrees as measured from the center of the backside surface of the sputtering plate <NUM>. The intersecting arcuate channels <NUM> break up the continuous trench structure of the circular grooves <NUM> to allow heat transfer fluid to circulate between the circular grooves <NUM> at the intersection points. The intersecting arcuate channels <NUM> have been found to significantly reduce stagnation of fluid within the continuous trench structures of the circular grooves <NUM>. Unexpectedly and surprisingly, the combination of the circular grooves <NUM> and intersecting arcuate channels <NUM> on the backside surface of the backing plate <NUM> were also found to substantially reduce the number of particles that deposit on a particular substrate during a sputtering process. The arcuate channels <NUM> may have a radiused cross-section.

In some implementations, linear channels may be used in place of arcuate channels <NUM>. The linear channels may be spaced apart from one another by an angle of from about <NUM> to about <NUM> degrees as measured from the center of the backside surface of the sputtering plate <NUM>. The linear channels may cut through the circular grooves <NUM> at angles ranging from <NUM> to <NUM> degrees relative to the localized horizontal tangent to the circular groove <NUM> at the point of intersection. The linear channels may have the same angle as the mean of the arcuate grooves <NUM>.

It is believed that the reduction in particulate contamination from the sputtering target results from the effect of the intersecting grooves and arcuate channels <NUM>, <NUM> on the fluid dynamics of the heat transfer fluid in the circular grooves <NUM> of the backside surface <NUM> of the sputtering target <NUM>. Generally, the heat transfer fluid at the bottom and nearest the walls of the circular grooves <NUM> moves more slowly than the bulk of the fluid because of friction between the fluid and the surface. This frictional effect can create a stagnant layer of hot fluid at the bottom of the circular grooves <NUM> on the backside surface <NUM> that reduces circulation of heat transfer fluid through the grooves. On backing plates that do not have intersecting grooves and arcuate channels, the stagnant layer of fluid remains trapped in the circular grooves <NUM> without exposure to excessive amounts of turbulence. Moreover, the heat transfer fluid is typically circulated by a magnet assembly that rotates about a central axis in the housing, which increases the laminar flow of fluid through the circular grooves <NUM>, further contributing to entrapping hot fluid within the circular grooves <NUM>. It is believed that the intersecting grooves <NUM> and arcuate channels <NUM> break up the circular grooves <NUM> into shorter segments and provide corners at the intersections, about which the fluid flow is turbulent. This turbulence stirs the stagnant layer at the bottom of the circular grooves <NUM> to force this fluid out of the groove and allow fresh, unheated fluid to enter the groove. The quicker moving circulating fluid is believed to considerably reduce the thickness and insulating effect of the slow moving stagnant layer, thereby increasing the heat transfer between the sputtering plate <NUM> and the heat transfer fluid.

The circular grooves <NUM> and arcuate channels <NUM> also provide an increase in total surface area of the backside surface <NUM> of the sputtering plate <NUM>. The grooved backside surface <NUM> can have a surface area that is from <NUM>% to <NUM>% greater than the surface area of a planar backside surface of a sputtering plate of similar dimensions. For example, if the surface area of the planar backside of a conventional sputtering plate is "A" cm<NUM>, the area of the grooved sputtering plate <NUM> will be <NUM> A to <NUM> A.

In one implementation, as shown in <FIG>, the circular grooves <NUM> are spaced apart and concentric to one another. In one implementation, the number of circular grooves ranges from about <NUM> grooves to about <NUM> grooves. In another implementation, the number of circular grooves ranges from about <NUM> circular grooves to about <NUM> circular grooves. In another implementation, the number of circular grooves ranges from about <NUM> circular grooves to about <NUM> circular grooves. In another implementation the number of grooves is about <NUM>. In another implementation, the number of grooves is about <NUM>. Those skilled in the art will realize that the number of grooves can vary depending on the fluid used and the specific application.

Each circular groove <NUM> comprises a Δr (distance between the outer radius of a particular circular groove <NUM> and its inner radius) ranging from about <NUM> to about <NUM>. In one example, Δr is about <NUM>. The circular ridges <NUM> between the circular grooves <NUM> have a width ranging from about from about <NUM> to about <NUM>. In one example, the circular ridges <NUM> between the circular grooves <NUM> have a width of about <NUM>. <FIG> shows the backside surface <NUM> having ten circular grooves <NUM> which are concentric and annular with eight intervening circular ridges <NUM>.

The distribution of the circular grooves <NUM> and circular ridges <NUM> is selected to overlap with the rotational track of the rotating magnet assembly, such that the region over which the magnet rotates is almost entirely covered with circular grooves <NUM> and circular ridges <NUM>. In one implementation, the circular grooves <NUM> are spread across an area of at least about <NUM>% of the area of the backside surface <NUM>, or even at least <NUM>% of the backside surface <NUM>, to maximize the effect of the circular grooves <NUM>. The higher coverage area of the circular grooves <NUM>, as compared to previous designs, serve to cooperatively dissipate additional heat from the backside surface <NUM> causing the whole sputtering target <NUM> to operate at cooler temperatures during sputter processing.

In one implementation, the circular grooves <NUM> comprise an innermost radially inner grove 150a and an outermost radially outer circular groove 150b, with a plurality of circular grooves <NUM> are distributed between the inner and outer circular grooves 150a, b. The inner diameter of the inner circular groove 150a is selected in relation to the diameter of the shaft of the rotating magnet assembly and can even be the same diameter as the magnet assembly shaft. The inner circular groove 150a is situated directly under the shaft, and the radius of the outer circular groove 150b is selected in relation to the maximum radius of rotation of the magnet assembly about the rotation shaft. For example, the radius of the outer circular groove 150b can be selected to be substantially the same as the maximum radius of rotation of the magnet assembly about the rotation shaft. This grooved surface provides an increased cooling surface area in the region corresponding both to the circulated fluid and to the regions of the sputtering surface <NUM> that have magnetically enhanced sputtering and may have the need for further temperature control.

The arcuate channels <NUM> intersect the circular grooves <NUM> by cutting through the plurality of circular ridges <NUM> of the circular grooves <NUM>. The arcuate channels <NUM> serve as drainage channels which prevent stagnation of heat transfer fluid within the circular grooves <NUM> to substantially improve heat transfer from the pattern of intersecting circular grooves and arcuate channels <NUM>, <NUM>, respectively. The arcuate channels <NUM> comprise arcs which are curved and extend primarily along the radial direction. The arcuate channels <NUM> are spaced apart from one another by a distance that varies across the radial direction, with a larger gap near the periphery of the backside surface <NUM> and a smaller distance closer to the center of the backside surface <NUM>. In one implementation, as shown <FIG>, the shape of each arcuate channel can be approximated by the polar equation: <MAT>.

In one implementation, the arcuate channels <NUM> are curved to be convex shaped relative to the direction of the rotating magnets in the chamber <NUM>, as shown by the arrow <NUM> in <FIG>. The shaped arcuate channels <NUM> prevent stagnation of heat transfer fluid within the circular grooves <NUM> by allowing heated fluid to escape from the circular grooves <NUM>. The arcuate shape in this direction encourages laminar flow of the fluid through and from the circular grooves <NUM>.

The arcuate channels <NUM> also can have a curved tip region <NUM> that tapers upward to the backside surface <NUM> of the backing plate <NUM>, as shown in <FIG> and <FIG>. The curved tip region <NUM> begins at about the radius of the outer circular groove 150b. The tapered tip is preferable over a stepwise tip because the tapered tip allows for a more laminar flow of fluid out of the ends of the arcuate channels <NUM>.

The circular grooves <NUM> and arcuate channels <NUM> can be formed by machining the backing plate <NUM>, for example, cutting by a lathe or milling. The corners of the circular grooves <NUM> and resultant circular ridges <NUM> can also be rounded in the machining process, to reduce erosion and stress concentration at the corners.

The grooved sputtering target may be manufactured using a CNC milling and/or lathe machine. Once a target blank is formed ball end milling cutters (for the milling machine) or radiused or single point lathe cutters, and then a ball end mill (multi head lathe or mill) may be used to form the grooves. The circular grooves can be formed on a lathe, the spiral or arcuate channels may then be cut using a milling system or a multi-head lathe. On a standard CNC milling system all grooves can be cut using a ball end mill trepanning the circles and arcs. The grooves are typically cut to a sufficient depth to facilitate adequate cooling of the sputtering target without being so deep as to reduce the structural rigidity of the sputtering target when under process conditions. For a <NUM> aluminum target, for example, the grooves can be on the order of. <NUM>" (<NUM>). For other target diameters and materials the groove size may be adjusted accordingly. For round targets circular grooves may be used because circular grooves are easy to manufacture and do not lead to uneven flexure of the sputtering target under vacuum loading. After, the spiral - arcuate - grooves may be added to facilitate center to edge water extraction aided by the spinning magnetron.

In one implementation, the sputtering plate <NUM> is mounted on the backing plate <NUM> which is a separate structure. The backing plate <NUM> has an annular-shaped body defined by a front surface <NUM>, an inner peripheral wall <NUM> and an annular flange <NUM>. The annular-shaped body <NUM> defines an open annulus <NUM>. The annular-shaped body <NUM> is typically sized to surround the backside surface <NUM> of the sputtering plate <NUM> and expose the backside surface <NUM> via the open annulus <NUM>. The front surface <NUM> supports the sputtering plate <NUM>. The annular flange <NUM> extends beyond the radius of the sputtering plate <NUM>. The annular flange <NUM> comprises a peripheral circular surface and has outer footing <NUM> that rests on an isolator <NUM> in the chamber <NUM>, as shown in <FIG>. The isolator <NUM> electrically isolates and separates the backing plate <NUM> from the chamber <NUM>, and is typically a ring made from a ceramic material, such as aluminum oxide.

An exemplary backing plate <NUM> is made from a metal alloy comprising copper-chrome. The resistivity of copper-chrome does not change until its temperatures exceed <NUM> degrees Celsius which is sufficiently high to exceed normal sputtering process temperatures. In one implementation, the copper-chrome alloy comprises a ratio of copper to chrome of from about <NUM>:<NUM> to about <NUM>:<NUM>. The copper-chrome alloy may comprise copper in a wt % of from about <NUM> to about <NUM> wt %, and chrome in a wt % of from about <NUM> to about <NUM> wt %. The copper-chrome alloy has a thermal conductivity of about <NUM> W/mK and an electrical resistivity of about <NUM>µohm cm. In some implementations, the backing plate <NUM> may be made from the materials disclosed in Table I.

Backing plates <NUM>, <NUM> may be composed of the backing plate materials disclosed in Table I. Sputtering plates <NUM>, <NUM> may be composed of the deposition materials disclosed in Table I. The backing plates <NUM>, <NUM> and sputtering plates <NUM>, <NUM> may be monolithic or bonded as depicted in the third column of Table I. Bonding of the backing plate to the sputtering plate may be performed by, for example, welding, diffusion bonding, soldering, brazing or forge bonding. The notation Al0.5Cu (wt. %) alloy indicates that the alloy includes <NUM> wt. As used herein, the term copper includes oxygen-free copper (e.g., C10100 - Oxygen-Free Electronic (OFE) - <NUM>%pure copper with <NUM>% oxygen content, C10200 - Oxygen-Free (OF), and C11000 - Electrolytic-Tough-Pitch (ETP)).

The backing plate <NUM> is typically made from a material selected to have a high thermal conductivity and to circulate a heat transfer fluid therein. A suitably high thermal conductivity of the backing plate <NUM> is at least about <NUM> W/mK, for example, from about <NUM> to about <NUM> W/mK. Such thermal conductivity levels allow the sputtering target <NUM> to be operated for longer process time periods by efficiently dissipating the heat generated in the sputtering target <NUM>. In one implementation, the backing plate <NUM> is made from a metal, such as copper or aluminum. In another implementation, the backing plate <NUM> comprises a metal alloy, such as for example copper-zinc (naval brass), or chromium-copper alloy. In one exemplary implementation the backing plate <NUM> comprises C18000 which is an alloy having component weights of Cr (<NUM>%), Cu (<NUM>%), Ni (<NUM>%) and Si (<NUM>%). The backing plate <NUM> can also be a separate structure containing one or more bonded plates.

The backing plate <NUM> can also have an electrical resistivity that is in a desirable range to reduce erosion grooving while still allowing operation of the sputtering target <NUM> for an extended time period. The electrical resistivity should be sufficiently low to allow the sputtering target <NUM> to be electrically biased or charged during sputtering. However, the electrical resistivity should also be sufficiently high to reduce the effect of eddy currents in the sputtering target <NUM>, as the heat generated by the eddy current as it travels along a pathway through the sputtering target <NUM> is proportional to the electrical resistance encountered along the pathway. In one implementation, the electrical resistivity of the backing plate <NUM> is from about <NUM> to about <NUM>µohm cm or even from about <NUM> to about <NUM>µohm cm.

In one implementation, the sputtering plate <NUM> is mounted on the front surface <NUM> of the backing plate <NUM> by diffusion bonding by placing the backing plate <NUM> and the sputtering target <NUM> on each other and heating the plates to a suitable temperature, typically at least about <NUM> degrees Celsius. Other exemplary methods for coupling the backing plate <NUM> to the sputtering target include soldering, vacuum or hydrogen brazing, diffusion bonding and forge bonding.

In one implementation, the sputtering surface <NUM> of the sputtering plate <NUM> is profiled to reduce flaking of process deposits as shown in <FIG> and <FIG>. In an exemplary implementation, the outer peripheral wall <NUM> forms a peripheral inclined rim <NUM> that surrounds the top plane <NUM> of the central cylindrical mesa <NUM>. The inclined rim <NUM> is inclined relative to a plane perpendicular to the top plane <NUM> of the central cylindrical mesa <NUM> by an angle α of at least about <NUM> degrees (e.g., from about <NUM> degrees to about <NUM> degrees; about <NUM> degrees).

<FIG> is a sectional side view of another implementation of a sputtering target <NUM> that may comprise the materials described in Table I. <FIG> is a perspective view of the back of the backing plate of <FIG> showing a plurality of intersection circular grooves and arcuate channels on the backside surface <NUM> of the backing plate <NUM>. The sputtering target <NUM> comprises a sputtering plate <NUM> mounted on a backing plate <NUM>. Unlike sputtering target <NUM>, the backing plate <NUM> is a solid backing plate including a plurality of intersecting circular grooves <NUM> (450a and 450b) and arcuate channels <NUM> on the backside surface of the backing plate. In some implementations, the backing plate <NUM> may be replaced by a flat backing plate that has a flat surface (e.g. does not contain the circular grooves and arcuate channels shown in <FIG>).

The sputtering plate <NUM> and backing plate <NUM> can be a monolith comprising a single structure made from the same high-purity material and that serves as both a backing plate and a sputtering plate or they may be separate structures that are bonded together to form a sputtering target. The sputtering plate <NUM> comprises a central cylindrical mesa <NUM> that serves as a sputtering surface <NUM>, and which has a top plane <NUM> that is maintained parallel to the plane of a substrate during use of the sputtering target <NUM> in a chamber (e.g., chamber <NUM>). The sputtering plate <NUM> is made from a metal or metal compound. For example, the sputtering plate <NUM> can be composed of any of the materials identified in Table I.

In one implementation, the sputtering plate <NUM> is mounted on a backing plate <NUM> which is a separate structure and which has a front surface <NUM> to support the sputtering plate <NUM> and an annular flange <NUM> that extends beyond the radius of the sputtering plate <NUM>. The annular flange <NUM> comprises a peripheral circular surface and has outer footing <NUM> that rests on an isolator <NUM> in the chamber <NUM>, as shown in <FIG>. The isolator <NUM> electrically isolates and separates the backing plate <NUM> from the chamber <NUM>, and is typically a ring made from a ceramic material, such as aluminum oxide.

An exemplary implementation of a sputtering process chamber <NUM> capable of processing a substrate <NUM> using the sputtering target <NUM> is shown in <FIG>. The chamber <NUM> comprises enclosure walls <NUM> that enclose a plasma zone <NUM> and include sidewalls <NUM>, a bottom wall <NUM>, and a ceiling <NUM>. The chamber <NUM> can be a part of a multi-chamber platform (not shown) having a cluster of interconnected chambers connected by a robot arm mechanism that transfers substrates <NUM> between the chamber. In the implementation shown, the process chamber <NUM> comprises a sputtering chamber, also called a physical vapor deposition or PVD chamber, which is capable of sputter depositing titanium on a substrate <NUM>. However, the chamber <NUM> can also be used for other purposes, such as for example, to deposit aluminum, copper, tantalum, tantalum nitride, titanium nitride, tungsten or tungsten nitride; thus, the present claims should not be limited to the exemplary implementations described herein to illustrate the disclosure.

In one implementation the chamber <NUM> is equipped with a process kit to adapt the chamber <NUM> for different processes. The process kit comprises various components that can be removed from the chamber <NUM>, for example, to clean sputtering deposits off the component surfaces, replace or repair eroded components. In one implementation, the process kit comprises a ring assembly <NUM> for placement about a peripheral wall of the substrate support <NUM> that terminates before an overhanging edge of the substrate <NUM>, as shown in <FIG>. The ring assembly <NUM> comprises a deposition ring <NUM> and a cover ring <NUM> that cooperate with one another to reduce formation of sputter deposits on the peripheral walls of the substrate support <NUM> or the overhanging edge of the substrate <NUM>.

The process kit can also includes a shield assembly <NUM> that encircles the sputtering surface <NUM> of the sputtering target <NUM> and the peripheral edge of the substrate support <NUM>, as shown in <FIG>, to reduce deposition of sputtering deposits on the sidewalls <NUM> of the chamber <NUM> and the lower portions of the substrate support <NUM>. As shown in <FIG>, shield assembly <NUM> comprises an upper shield <NUM> and a lower shield <NUM>. Portions of the shield assembly <NUM>, such as for example the upper shield <NUM>, can be biased during substrate processing in order to affect the chamber environment. The shield assembly <NUM> reduces deposition of sputtering material on the surfaces of the substrate support <NUM>, sidewalls <NUM> and bottom wall <NUM> of the chamber <NUM>, by shadowing these surfaces.

The process chamber <NUM> comprises a substrate support <NUM> to support the substrate <NUM> which comprises a pedestal <NUM>. The pedestal <NUM> has a substrate receiving surface <NUM> that receives and supports the substrate <NUM> during processing, the substrate receiving surface <NUM> having a plane substantially parallel to the sputtering surface <NUM> of the overhead sputtering target <NUM>. The substrate support <NUM> can also include an electrostatic chuck <NUM> to electrostatically hold the substrate <NUM> and/or a heater (not shown), such as an electrical resistance heater or heat exchanger. In operation, a substrate <NUM> is introduced into the chamber <NUM> through a substrate loading inlet (not shown) in the sidewall <NUM> of the chamber <NUM> and placed on the substrate support <NUM>. The substrate support <NUM> can be lifted or lowered to lift and lower the substrate <NUM> onto the substrate support <NUM> during placement of a substrate <NUM> on the substrate support <NUM>. The pedestal <NUM> can be maintained at an electrically floating potential or grounded during plasma operation.

During a sputtering process, the sputtering target <NUM>, the substrate support <NUM>, and upper shield <NUM> are electrically biased relative to one another by a power supply <NUM>. The sputtering target <NUM>, the upper shield <NUM>, the substrate support <NUM>, and other chamber components connected to the power supply <NUM> of the sputtering target operate as a gas energizer to form or sustain a plasma of the sputtering gas. The gas energizer can also include a source coil (not shown) that is powered by the application of a current through the coil. The plasma formed in the plasma zone <NUM> energetically impinges upon and bombards the sputtering surface <NUM> of the sputtering target <NUM> to sputter material off the sputtering surface <NUM> onto the substrate <NUM>.

The sputtering gas is introduced into the chamber <NUM> through a gas delivery system <NUM> that provides gas from a process gas source <NUM> via conduits <NUM> having gas flow control valves <NUM>, such as a mass flow controllers, to pass a set flow rate of the gas therethrough. The gases are fed to a mixing manifold (also not shown) in which the gases are mixed to form a process gas composition and fed to a gas distributor <NUM> having gas outlets in the chamber <NUM>. The process gas source <NUM> may comprise a non-reactive gas, such as argon or xenon, which is capable of energetically impinging upon and sputtering material from a target. The process gas source <NUM> may also include a reactive gas, such as one or more of an oxygen-containing gas and a nitrogen-containing gas, that are capable of reacting with the sputtered material to form a layer on the substrate <NUM>. Spent process gas and byproducts are exhausted from the chamber <NUM> through an exhaust <NUM> which includes exhaust ports <NUM> that receive spent process gas and pass the spent gas to an exhaust conduit <NUM> having a throttle valve <NUM> to control the pressure of the gas in the chamber <NUM>. The exhaust conduit <NUM> is connected to one or more exhaust pumps <NUM>. Typically, the pressure of the sputtering gas in the chamber <NUM> is set to sub-atmospheric levels, such as a vacuum environment, for example, gas pressures of <NUM> mTorr to <NUM> mTorr.

The chamber <NUM> can also include a heat exchanger comprising a housing <NUM> capable of holding a heat transfer fluid which is mounted abutting the backside surface <NUM> of the sputtering target <NUM>. The housing <NUM> comprises walls which are sealed about the backside surface <NUM> of the sputtering target <NUM>. The housing <NUM> can be made from an insulating medium, such as fiberglass. A heat transfer fluid, such as chilled deionized water, is introduced into the housing <NUM> though an inlet and is removed from the housing <NUM> through an outlet (not shown). The heat exchanger serves to maintain the sputtering target <NUM> at lower temperatures to further reduce the possibility of forming erosion grooves and microcracks in the sputtering target <NUM>.

The chamber can also include a magnetic field generator <NUM> comprising a plurality of rotatable magnets. In one implementation, as shown in <FIG>, the magnetic field generator <NUM> comprises two sets of rotatable magnets <NUM>, <NUM> that are mounted on a common plate <NUM> and capable of rotating about a central axis in back of the sputtering target <NUM>.

The first set of rotatable magnets <NUM> comprises one or more central magnets <NUM> having a first magnetic flux or magnetic field orientation, and one or more peripheral magnets <NUM> having a second magnetic flux or magnetic field orientation. In one implementation, the ratio of the first magnetic flux to the second magnetic flux is at least about <NUM>:<NUM>, for example, from about <NUM>:<NUM> to about <NUM>:<NUM>, or even about <NUM>:<NUM>. This allows the magnetic field from the peripheral magnets <NUM> to extend deeper into the chamber <NUM> towards the substrate <NUM>. In one example, the first set of rotatable magnets <NUM> comprises a set of central magnets <NUM> having a first magnetic field orientation, surrounded by a set of peripheral magnets <NUM> having a second magnetic field orientation. For example, the second magnetic field orientation can be generated by positioning the peripheral magnets <NUM> so that their polarity direction is opposite to the polarity direction of the central magnets <NUM>.

The implementation of <FIG> shows a second, larger set of rotatable magnets <NUM>. The second set of rotatable magnets <NUM> comprises a central magnet <NUM> having a first magnetic flux or magnetic field orientation, and a peripheral magnet <NUM> with a second magnetic flux or magnetic field orientation. In one implementation, the ratio of the first magnetic flux to the second magnetic flux is about <NUM>:<NUM>.

The magnetic field generator <NUM> comprises a motor <NUM> and axle <NUM> to rotate the common plate <NUM> on which the sets of rotatable magnets <NUM>, <NUM> are mounted. The rotation system rotates the sets of rotatable magnets <NUM>, <NUM> at from about <NUM> to about <NUM> rpm, for example, about <NUM> to about <NUM> rpm. In one implementation, the sets of rotatable magnets <NUM>, <NUM> comprise NdFeB. The first set of rotatable magnets <NUM> is used to scan the edge of the sputtering target <NUM> to produce a highly ionized sputter flux. The second set of rotatable magnets <NUM> can be used to produce a flux of ion bombardment about the central and peripheral regions of the sputtering target <NUM>. The larger, or second set of rotatable magnets <NUM> can be switched on to clean sputter material redeposited on the sputtering target center and about the periphery. In addition to providing a rotating and changing magnetic field about the sputtering surface <NUM>, the magnetic field generator <NUM> and sets of rotatable magnets <NUM>, <NUM> push and stir the heat transfer fluid, thereby circulating a heat transfer fluid in the housing <NUM>.

To counteract the large amount of power delivered to the sputtering target <NUM>, the back of the sputtering target <NUM> may be sealed to a backside coolant chamber. The backside coolant chamber can be separate from the housing <NUM>, or the coolant chamber and housing <NUM> can be a single integrated chamber as shown in <FIG>. Heat transfer fluid <NUM> comprising, for example, chilled deionized water or other cooling liquid, is circulated through the interior of the coolant chamber to cool the sputtering target <NUM>. The magnetic field generator <NUM> is typically immersed in the heat transfer fluid <NUM>, and the axle <NUM> passes through the backside chamber through a rotary seal <NUM>.

The chamber <NUM> is controlled by a controller <NUM> that comprises program code having instruction sets to operate components of the chamber <NUM> to process substrates <NUM> in the chamber <NUM>. For example, the controller <NUM> can comprise program code that includes a substrate positioning instruction set to operate the substrate support <NUM> and substrate transport; a gas flow control instruction set to operate gas flow control valves <NUM> to set a flow of sputtering gas to the chamber <NUM>; a gas pressure control instruction set to operate the throttle valve <NUM> to maintain a pressure in the chamber <NUM>; a gas energizer control instruction set to operate the gas energizer to set a gas energizing power level; a temperature control instruction set to control a temperature control system (not shown) in the pedestal <NUM> or wall <NUM> to set temperatures of the substrate <NUM> or walls <NUM>, respectively; and a process monitoring instruction set to monitor the process in the chamber <NUM>.

The sputtering process can be used to deposit a layer comprising titanium or a titanium compound on a substrate. The titanium layers can be used by themselves, or in combination with other layers. For example, a sputtered titanium layer can be used as a barrier layer, e.g., Ti/TiN stacked layers are often used as liner barrier layers and to provide contacts to the source and drain of a transistor. In another example, a titanium layer is deposited on a silicon wafer and portions of the titanium layer in contact with the silicon are converted to titanium silicide layers by annealing. In another configuration, the diffusion barrier layer below a metal conductor, includes a titanium oxide layer formed by sputter depositing titanium on the substrate <NUM> and then transferring the substrate to an oxidizing chamber to oxidize the titanium by heating it in an oxygen environment to form titanium oxide. Titanium oxide can also be deposited by introducing oxygen gas into the chamber while titanium is being sputtered. Titanium nitride can be deposited by reactive sputtering methods by introducing a nitrogen containing gas into the chamber while sputtering titanium.

The present disclosure has been described with reference to certain preferred implementations thereof; however, other implementations are possible. For example, the sputtering plate <NUM> and backing plate <NUM> of the sputtering target <NUM> can be made from materials other than those described herein, and can also have other shapes and sizes. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred implementations contained herein.

Claim 1:
A sputtering target for a sputtering chamber, the sputtering target comprising:
a sputtering plate (<NUM>) comprising a central cylindrical mesa (<NUM>) arranged to serve as a sputtering surface (<NUM>), a backside surface (<NUM>) opposing the sputtering surface (<NUM>), wherein the backside surface (<NUM>) has radially inner, middle and outer regions, a back surface (<NUM>) opposite the sputtering surface (<NUM>), an outer peripheral wall (<NUM>) and an inner peripheral wall (<NUM>), the outer peripheral wall (<NUM>) extending from the sputtering surface (<NUM>) to the back surface (<NUM>) and the inner peripheral wall (<NUM>) extending from the backside surface (<NUM>) to the back surface (<NUM>), wherein a recess (<NUM>) that exposes the backside surface (<NUM>) of the sputtering plate (<NUM>) is formed between the backside surface (<NUM>) and the inner peripheral wall (<NUM>), the backside surface (<NUM>) having:
a plurality of circular grooves (<NUM>) which are spaced apart from one another; and
at least one arcuate channel (<NUM>), or linear channels, cutting through the circular grooves (<NUM>) and extending from the radially inner region to the radially outer region of the sputtering plate; and
an annular-shaped backing plate (<NUM>) mounted to the sputtering plate (<NUM>), wherein the annular-shaped backing plate (<NUM>) defines an open annulus (<NUM>) exposing the backside surface (<NUM>) of the sputtering plate (<NUM>).