Samsung Electronics Co., Ltd. v. Demaray LLC
`Samsung Electronic's Exhibit 1052 Vol 1.
`Exhibit 1052, Page 1
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`M-12245 US
`852923 vl
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`Express Mail Label No.
`EL 941069152 US
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`Biased Pulse DC Reactive Sputtering of Oxide Films
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`Hongmei Zhang
`Mukundan Narasimhan
`Ravi Mullapudi
`Richard E. Demaray
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`Background
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`1. Field of the Invention
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` high dielectric insulators.
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`[0001] The present invention relates to deposition of oxide and oxynitride films and, in
`particular, to deposition of oxide and oxynitride films by pulsed DC reactive sputtering.
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`2. Discussion of Related Art
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`Deposition of insulating materials and especially optical materials is
`[0002]
`technologically important in several areas including productionofoptical devices and production
`of semiconductor devices. In semiconductor devices, doped aluminasilicates can be utilized as
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`[0003] The increasing prevalence offiber optic communications systemshas created an
`unprecedented demandfor devices for processing optical signals. Planar devices suchasoptical
`waveguides, couplers, splitters, and amplifiers, fabricated on planar substrates, like those
`commonly used for integrated circuits, and configured to receive andprocesssignals from
`optical fibers are highly desirable. Such devices hold promise for integrated optical and
`electronic signal processing on a single semiconductor-like substance.
`
`[0004] The basic design ofplanar optical waveguides and amplifiers is well known, as
`described, for example, in U. S. Patent Nos. 5,119,460 and 5,563,979 to Bruceet al., 5,613,995
`to Bhandarkar et al., 5,900,057 to Buchalet al., and 5,107,538 to Bentonet al., to cite only a few.
`These devices, very generally, include a core region, typically bar shaped, of a certain refractive
`index surroundedbya cladding region of a lowerrefractive index. In the case ofan optical
`amplifier, the core region includes a certain concentration of a dopant, typically a rare earth ion
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`[0005] As described, for example in the patents by Bruceet al., Bhandarkaret al, and Buchalet
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`al., planar optical devices may be fabricated by process sequences including forminga layer of
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`cladding material on a substrate; forming a layer of core material on the layer of cladding mater;
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`patterning the core layer using a photolighotgraphic mask and an etching process to form a core
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`ridge; and covering the core ridge with an upper cladding layer.
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`[0006] The performance ofthese planar optical devices depends sensitively on the value and
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`uniformity of the refractive index of the core region and of the cladding region, and particularly
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`on the difference in refractive index, An, between the regions. Particularly for passive devices
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`such as waveguides, couplers, and splitters, An should be carefully controlled, for example to
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`values within about 1 %, and the refractive index of both core and cladding needto be highly
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`uniform, for some applications at the fewer than parts per thousandlevel. In the case of doped
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`materials forming the core region of planar optical amplifiers,it is important that the dopant be
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`uniformly distributed so as to avoid non-radiative quenchingor radiative quenching, for example
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`by upconversion. The refractive index and other desirable properties of the core and cladding
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`regions, such as physical and chemical uniformity, low stress, and high density, depend,of
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`course, on the choice of materials for the devices and on the processes by which they are
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`fabricated.
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`such as an erbium or praseodymium ion which, when pumped bya laser, fluoresces, for
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`example, in the 1550 nm and 1300 nm wavelength ranges used for optical communication, to
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`amplify the optical signal passing through the core.
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`[0007] Because of their optical properties, silica and refractory oxides such as Al,Q3, are good
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`candidate materials for planar optical devices. Further, these oxides serve as suitable hosts for
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`rare earth dopants used in optical amplifiers. A common material choice is so-called low
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`temperature glasses, doped with alkali metals, boron, or phosphorous, which have the advantage
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`of requiring lower processing temperatures. In addition, dopants are used to modify the
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`refractive index. Methods such as flame hydrolysis, ion exchange for introducing alkali ions in
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`glasses, sputtering, and various chemical vapor deposition processes (CVD)have been used to
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`' form films of doped glasses. However, dopants such as phosphorous and boron are hygroscopic,
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`and alkalis are undesirable for integration with electronic devices. Control of uniformity of
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`doping in CVD processes can be difficult and CVD deposited films can havestructural defects
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`2.
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`present invention includes a pulsed DC powersupply coupled throughafilter to a target and a
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`[0010] In accordance with the present invention, a sputtering reactor apparatus for depositing
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`oxide and oxynitride films is presented. Further, methods for depositing oxide and oxynitride
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`films for optical waveguide devices are also presented. A sputtering reactor according to the
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`substrate electrode coupled to an RF powersupply. A substrate mounted on the substrate
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`electrode is therefore supplied with a bias from the RF powersupply.
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`[0011] The target can be a metallic target made of a material to be deposited on the substrate. In
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`some embodiments, the metallic target is formed from Al], Si and various rare-earth ions. A
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`target with an erbium concentration, for example, can be utilized to deposit a film that can be
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`formed into a waveguideoptical amplifier.
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`[0012] A substrate can be any material and, in some embodiments,is a silicon wafer. In some
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`leading to scattering losses when usedto guide light. In addition, doped low temperature glasses
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`may require further processing after deposition. A method for eliminating bubbles in thin films
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`of sodium-boro-silicate glass by high temperature sintering is described, for example, in the ‘995
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`patent to Bhandarkaretal.
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`[0008] Typically, RF sputtering has been utilized for deposition of oxide dielectric films.
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`However, RF sputtering utilizes ceramic targets which are typically formed of multiple smaller
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`tiles. Since the tiles can not be made very large, there may be a large problem ofarcing between
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`tiles and therefore contamination of the deposited film due to this arcing. Further, the reactors
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`required for RF sputtering tend to be rather complicated. In particular, the engineering of low
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`capacitance efficient RF powerdistribution to the cathodeis difficult in RF systems. Routing of
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`low capacitance forward and return powerinto a vacuum vessel of the reaction chamber often
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`exposes the power path in such a waythat diffuse plasma discharge is allowed under some
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`conditions of impedance tuning of the matching networks.
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`[0009] Therefore, there is a need for new methods of depositing oxide and oxynitride films and
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`for forming planar optical devices.
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`Summary
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`embodiments, RF power can be supplied to the wafer. In some embodiments,the wafer and the
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`electrode can be separated by an insulating glass.
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`[0013] In some embodiments, up to about 10 kW ofpulsed DC powerat a frequency of between
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`about 40 kHz and 350 kHz and a reverse pulse time of up to about 5 ps is suppliedto thetarget.
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`The wafer can be biased with up to about several hundred watts of RF power. The temperature
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`of the substrate can be controlled to within about 10° C and can vary from about -50° C to
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`several hundred degrees C. Process gasses can be fed into the reaction chamberof the reactor
`apparatus. In some embodiments, the process gasses can include combinations of Ar, N2, O2,
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`C2F¢, CO2, CO and other process gasses.
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`[0014] Several material properties of the deposited layer can be modified by adjusting the
`composition ofthe target, the composition and flow rate of the process gasses, the power
`supplied to the target and the substrate, and the temperature of the substrate. For example, the
`index of refraction of the deposited layer depends on deposition parameters. Further, in some
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`embodiments stress can be relieved on the substrate by depositing a thin film of material on a
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`back side of the wafer. Films deposited according to the present invention can beutilized to
`form optical waveguide devices such as multiplexers and rare-earth doped amplifiers.
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`[0015] These and other embodiments, along with examples of material layers deposited
`according to the present invention, are further described below with respect to the following
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`figures.
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`Brief Description of the Figures
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`
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`[0016] Figures 1A and 1B showapulsed DCsputtering reactor according to the present
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`invention.
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`[0017] Figure 2 showsa planar view oftarget utilized in a reactor as shownin Figures 1A and
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`1B.
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`[0018] Figure 3 showsa cross-section view of an example target utilized in a reactor as shown in
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`Figures 1A and 1B.
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`[0019] Figure 4 showsa flow chart of an embodimentof a process for depositing a film on a
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`substrate according to the present invention.
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`[0020] Figure 5 showsa hysterises curve of target voltage versus oxygen flow rates for an
`example target in an embodimentof a reactor according to the present invention.
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`[0021] Figure 6 shows a photo-luminescence andlifetimes of a film deposited in a process
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`according to the present invention as a function of after deposition anneal temperature.
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`[0022] Figure 7 showsthe relationship betweenthe index of refraction ofa film as a function of
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`deposited oxide layers according to the present invention and due to oxide build-up onthetarget.
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`[0023] Figure 8 showsa graphofthe index ofrefraction of a film deposited accordingto the
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`present invention as a function of the aluminum content in a composite AI/Sitarget.
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`[0024} Figure 9 showsa graph of typical indices of refraction of material layers deposited
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`according to the present invention.
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`[0025] Figure 10 showsa table ofindices ofrefraction for a silica layer deposited according to
`the present invention as a function of different process parameters.
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`[0026] Figure 11 showsthe refractive indices as a function of O2/Ar ratio utilized in an Alumina
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`process according to the present invention.
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`[0027] Figure 12 showsthe refractive indices as a function of DC pulsed power frequency for an
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`Alumina layer deposited according to the present invention.
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`[0028] Figure 13 showsvariation in the refractive index over time during repeated depositions
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`from a single target.
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`[0029] Figure 14 showsvariation in refractive index over time for repeated depositions from a
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`target of another material layer according to the present invention.
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`[0030] Figure 15 showsthe variation refractive index over time for repeated depositions from a
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`target of another material layer according to the present invention.
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`[0031] Figure 16A through 16D shows a TEM film deposited according to the present invention.
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`[0032] Figure 17 showsthe transparency of a film deposited according to the present invention.
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`[0033] Figure 18 showsan uppercladding layer deposited according to the present invention
`over a multiple-waveguide structure such that the deposited layer is substantially planarized.
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`[0034] Figure 19 illustrates the deposition of a film over a waveguidestructure.
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`[0035] Figures 20 and 21 illustrate different etch and deposition rates for deposition offilms as a
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`function of the surface angle ofthe film.
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`[0036] Figure 22 illustrates calculation of the planarization time for a particular deposition
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`process.
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`[0037] Figures 23 through 25 through illustrate adjustment of process parameters in order to
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`achieve planarization of a film deposited over a waveguide structure according to the present
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`[0040] Figure 28 shows up-conversion constants, and lifetimes of the active core layer of Figure
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`27 deposited according to the present invention.
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`[0041] Figure 29 showsdrift in the index of refraction with subsequent depositions for films
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`deposited from a target according to the present invention.
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`[0042] Figure 30 showsdrift in the photoluminescence with subsequent depositions according to
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`the present invention.
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`. [0043] Figure 31 showsdrift in the excited state lifetime with subsequent depositions according
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`to the present invention.
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`[0044] Figure 32 showsstabilization of the index of refraction in subsequent depositions.
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`[0045] Figure 33 showsthe index of refraction of a film formed from a puresilicon target as a
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` invention.
` [0039] Figures 27 showsgain, insertion loss of a waveguide with an active core deposited
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`[0038] Figure 26 showsthe gain characteristics of an erbium doped waveguide amplifier formed
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`of films depositions according to the present invention.
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`according to the present invention.
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`function of the ratio of O2/N2 in the process gas.
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`[0046] In the figures, elements having the same designation have the sameor similar function.
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`Detailed Description
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`
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`[0047] Reactive DC magnetron sputtering of nitrides and carbides is a widely practiced
`technique, but the reactive dc magnetron sputtering ofnonconducting oxidesis donerarely.
`Films such as aluminum oxide are almost impossible to deposit by conventional reactive DC
`magnetron sputtering due to rapid formationof insulating oxide layers on the target surface. The
`insulating surfaces charges up andresult in arcing during process. This arcing can damagethe
`powersupply, produce particles and degrade the properties of deposited oxide films.
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`[0048] RF sputtering of oxide films is discussed in Application Serial No. 09/903,050 (the ‘050
`application) by Demarayetal., entitled “Planar Optical Devices and Methodsfor Their
`Manufacture,” assigned to the sameassigneeas is the present invention, herein incorporated by
`referencein its entirety. Further, targets that can be utilized in a reactor accordingto the present
`invention are discussed in U.S. Application serial no. {Attorney Docket No. M-12247 US} (the
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`‘247 application), filed concurrently with the present disclosure, assigned to the same assignee as
`is the present invention, herein incorporated by referencein its entirety. A gain-flattened
`amplifier formed offilms deposited according to the present invention are described in U.S.
`Application serial no. {Attorney Docket No. M-12652 US} (the ‘652 application), filed
`concurrently with the present disclosure, assigned to the same assignee as is the present
`invention, herein incorporated by reference in its entirety. Further, a mode size converter formed
`with films deposited according to the present invention is described in U.S. Application serial no.
`{Attorney Docket No. M-12138 US} (the ‘138 application), filed concurrently with the present
`disclosure, assigned to the sameassigneeas is the present invention, herein incorporated by
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`reference in its entirety.
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`[0049] Figure 1A shows a schematic of a reactor apparatus 10 for sputtering of material from a
`target 12 according to the present invention. In some embodiments, apparatus 10 may, for
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`example, be adapted from an AKT-1600 PVD (400 X 500 mm substrate size) system from
`Applied Komatsu or an AKT-4300 (600 X 720 mm substrate size) system from Applied
`Komatsu, Santa Clara, CA. The AKT-1600 reactor, for example, has three deposition chambers
`connected by a vaculum transport chamber. These Komatsu reactors can be modified such that
`pulsed DC poweris supplied to the target and RF poweris supplied to the substrate during
`deposition of a material film.
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`[0050] Apparatus 10 includes a target 12 whichis electrically coupled through a filter 15 to a
`pulsed DC powersupply 14. In some embodiments, target 12 is a wide area sputter source
`target, which provides material to be deposited on substrate 16. Substrate 16 is positioned
`parallel to and opposite target 12. Target 12 functions as a cathode when power1s appliedtoit
`and is equivalently termed a cathode. Application of power to target 12 creates a plasma 53.
`Substrate 16 is capacitively coupled to an electrode 17 through an insulator 54. Electrode 17 can
`be coupled to an RF power supply 18. Magnet 20 is scanned acrossthe top oftarget 12.
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` discharged andarcing is prevented. To obtain arc free deposition, the pulsing frequency exceeds
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`[0051] For pulsed reactive dc magnetron sputtering, as performed by apparatus10,the polarity
`of the power supplied to target 12 by power supply 14 oscillates between negative and positive
`potentials. During the positive period, the insulating layer on the surface of target 12 is
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`a critical frequency that depend on target material, cathode current and reverse time. High
`quality oxide films can be made using reactive pulse DC magnetron sputtering in apparatus 10.
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`[0052] Pulsed DC power supply 14 can be any pulsed DC power supply, for example an AE
`Pinnacle plus 10K by Advanced Energy, Inc. With this example supply, up to 10 kW ofpulsed
`DC powercan be supplied at a frequency of between 0 and 350 KHz. The reverse voltageis
`10% of the negative target voltage. Utilization of other power supplies will lead to different
`powercharacteristics, frequency characteristics and reverse voltage percentages. The reverse
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`time on this embodiment of power supply 14 can be adjusted between 0 and 5 is.
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`[0053] Filter 15 prevents the bias power from power supply 18 from coupling into pulsed DC
`powersupply 14. In some embodiments, power supply 18 is a2 MHz RF powersupply,for
`example can be a Nova-25 power supply made by ENI, Colorado Springs, Co.
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`[0054] Therefore, filter 15 is a 2 MHz bandrejectionfilter. In some embodiments, the band
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` magnet with dimension about 150 mm by 600 mm.
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`distance between target 12 and substrate 16 can be between about 3 and about 9 cm. Process gas
`can be inserted into the chamber of apparatus 10 at a rate up to about 200 sccm while the
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`pressure in the chamber of apparatus 10 can be held at between about .7 and 6 millitorr. Magnet
`20 provides a magnetic field of strength between about 400 and about 600 Gauss directed in the
`plane of target 12 and is movedacrosstarget 12 at a rate of less than about 20-30 sec/scan. In
`some embodimentsutilizing the AKT 1600 reactor, magnet 20 can be a race-track shaped
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`width of the filter can be approximately 100 kHz. Filter 15, therefore, prevents the 2 MHz
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`powerfrom thebias to substrate 16 from damaging powersupply 18.
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`[0055] However, both RF and pulsed DC deposited filmsare not fully dense and mostlikely
`have columnarstructures. These columnarstructures are detrimental for optical wave guide
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`applications due to the scattering loss caused by the structure. By applying a RF bias on wafer
`16 during deposition, the deposited film can be dandified by energetic ion bombardmentand the
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`columnar structure can be substantially eliminated.
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`[0056] In the AKT-1600 based system,for example, target 12 can have an active size of about
`675.70 X 582.48 by 4 mm in orderto deposit films on substrate 16 that have dimension about
`400 X 500 mm. The temperature of substrate 16 can be held at between —50C and 500C. The
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`[0057] A top down view of magnet 20 and wide area target 12 is shown in Figure 2. A film
`deposited on a substrate positioned on carrier sheet 17 directly opposed to region 52 of target 12
`has good thickness uniformity. Region 52 is the region shown in Figure 1B that is exposed to a
`uniform plasma condition. In some implementations, carrier 17 can be coextensive with region
`52. Region 24 shown in Figure 2 indicates the area below which both physically and chemically
`uniform deposition can be achieved, where physical and chemical uniformity providerefractive
`index uniformity, for example. Figure 2 indicates that region 52 of target 12 that provides
`thickness uniformity is, in general, larger than region 24 of target 12 providing thickness and
`chemical uniformity. In optimized processes, however, regions 52 and 24 maybe coextensive.
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`[0058] In some embodiments, magnet 20 extends beyond area 52 in onedirection, the Y
`direction in Figure 2, so that scanningis necessary in only one direction, the X direction, to
`provide a time averaged uniform magnetic field. As shown in Figures 1A and 1B, magnet 20
`can be scanned overthe entire extent of target 12, whichis larger than region 52 of uniform
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`sputter erosion. Magnet 20 is movedin a plane parallel to the plane of target 12.
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`[0059] The combination of a uniform target 12 with a target area 52 larger than the area of
`substrate 16 can provide filmsofhighly uniform thickness. Further, the material properties of
`the film deposited can be highly uniform. The conditionsofsputtering at the target surface, such
`as the uniformity of erosion, the average temperature of the plasmaat the target surface and the
`equilibration of the target surface with the gas phase ambient ofthe process are uniform over a
`region which is greater than or equalto the region to be coated with a uniform film thickness. In
`addition, the region ofuniform film thickness is greater than or equalto the region of the film
`which is to have highly uniform optical properties such as index ofrefraction, density,
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`transmission or absorptivity.
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`[0060] Target 12 can be formed of any materials, butis typically metallic materials such as, for
`example, combinations of Al and Si. Therefore, in some embodiments, target 12 includes a
`metallic target material formed from intermetalic compoundsofoptical elements such as Si, Al,
`Er and Yb. Additionally, target 12 can be formed, for example, from materials such as La, Yt,
`Ag, Au, and Eu. To form optically active films on substrate 16, target 12 can includerare-earth
`ions. In some embodimentsoftarget 12 with rare earth ions, the rare earth ions can be pre-
`alloyed with the metallic host componentsto form intermetalics. See the “247 application.
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`[0061] In several embodiments of the invention, materialtiles are formed. Thesetiles can be
`mounted on a backingplate to form a target for apparatus 10. Figure 3A shows an embodiment
`of target 12 formed with individualtiles 30 mounted on a cooled backplate 25. In order to form
`a wideareatarget ofan alloy target material, the consolidated material of individualtiles 30
`should first be uniform to the grain size of the powder from whichit is formed.It also should be
`formedinto a structural material capable of forming andfinishingto a tile shape having a surface
`roughnesson the order ofthe powdersize from whichit is consolidated. A wide area sputter
`cathode target can be formed from a close packed array of smallertiles. Target 12, therefore,
`may include any numberoftiles 30, for example between 2 to 20 individualtiles 30. Tiles 30 are
`finished to a size so as to provide a margin of non-contact,tile to tile, 29 in Figure 3A,less than
`about 0.010” to about 0.020”or less than half a millimeter so as to eliminate plasma processes
`between adjacent onesoftiles 30. The distance betweentiles 30 of target 12 and the dark space
`anode or ground shield 19, in Figure 1B can be somewhat larger so as to provide non contact
`assemblyor provide for thermal expansion tolerance during process chamber conditioning or
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`operation.
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`[0062] Several useful examplesoftarget 12 that can be utilized in apparatus 10 accordingto the
`present invention include the following targets compositions: (Si/Al/Er/Yb) being about
`(57.0/41.4/0.8/0.8), (48.9/49/1.6/0.5), (92/8/0/0), (60/40/0/0), (50/50/0/0), (65/35/0/0),
`(70/30/0,0), and (50,48.5/1.5/0) cat. %, to list only a few. These targets can be referred to as the
`0.8/0.8 target, the 1.6/.5 target, the 92-8 target, the 60-40target, the 50-50 target, the 65-35
`target, the 70-30target, and the 1.5/0 target, respectively. The 0.8/0.8, 1.6/0.5, and 1.5/0 targets
`can be madebypre-alloyed targets formed from an atomization and hot-isostatic pressing
`(HIPing) processas describedin the ‘247 application. The remaining targets can be formed, for
`example, by HIPing. Targets formed from Si, Al, Er and Yb can have any composition. In some
`embodiments, the rare earth content can be up to 10 cat. % of the total ion content in the target.
`Rare earth ions are added to form active layers for amplification. Targets utilized in apparatus
`10 can have any composition and can include ions other than Si, Al, Er and Yb, including: Zn,
`Ga, Ge, P, As, Sn, Sb, Pb, Ag, Au, and rare earths: Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy Ho,Er,
`
` [0063] Optically useful materials to be deposited onto substrate 16 include oxides, fluorides,
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`Tm Yb and Lu.
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`sulfides, nitrides, phosphates, sulfates, and carbonates, as well as other wide band gap
`semiconductor materials. To achieve uniform deposition,target 12,itself can be chemically
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`uniform and of uniform thickness over an extendedarea.
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`[0064] Target 12 can be a composite target fabricated from individualtiles, precisely bonded
`together on a backing plate with minimal separation, as is discussed further with respect to
`Figure 3. In some embodiments, the mixed intermetallics can be plasma sprayed directly onto a
`backing plate to form target 12. The complete target assembly can also includes structures for
`cooling the target, embodiments of which have been described in U. S. Patent No. 5,565,071 to
`Demarayet al, and incorporated herein by reference.
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`[0065] Substrate 16 can be a solid, smooth surface. Typically, substrate 16 can be a silicon
`waferor a silicon wafer coated with a layer of silicon oxide formed by a chemical vapor
`deposition process or by a thermal oxidation process. Alternatively, substrate 16 can bea glass,
`such as Corning 1737 (Corning Inc., Elmira, NY), a glass-like material, quartz, a metal, a metal
`oxide, or a plastic material. Substrate 16 can be supported on a holderor carrier sheet that may
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`be larger than substrate 16. Substrate 16 can beelectrically biased by powersupply 18.
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`[0066] In some embodiments,the area of widearea target 12 can be greater than the area on the
`carrier sheet on which physically and chemically uniform deposition is accomplished. Secondly,
`in some embodimentsa central region on target 12, overlying substrate 16, can be provided with
`a very uniform condition of sputter erosion of the target material. Uniform target erosionis a
`consequenceofa uniform plasma condition. In the following discussion,all mention of uniform
`condition of target erosion is taken to be equivalent to uniform plasma condition. Uniform target
`erosion is evidenced by the persistence of film uniformity throughout an extendedtargetlife. A
`uniformly deposited film can be defined as a film having a nonuniformity in thickness, when
`measured at representative points on the entire surface of a substrate wafer, of less than about 5
`% or 10%. Thickness nonuniformity is defined, by convention, as the difference between the
`minimum and maximum thickness divided by twice the average thickness. If films deposited
`from a target from which more than about 20 % ofthe weight of the target has been removed
`continue to exhibit thickness uniformity, then the sputtering process is judged to be ina
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`condition of uniform target erosion for all films deposited duringthe target life.
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` region 51, which extends underthe entire target 12. A central region 52 of target 12, can
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` Ex. 1052, Page 13
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`[0067] As shownin Figure 1B, a uniform plasma condition can be created in the region between
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`target 12 and substrate 16 in a region overlying substrate 16. A plasma 53 can be created in
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`experience a condition of uniform sputter erosion. As discussed further below, a layer deposited
`on a substrate placed anywhere below central region 52 can then be uniform in thickness and
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`other properties (i.e., dielectric, optical index, or material concentrations).
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`[0068] In addition, region 52 in which deposition provides uniformity of deposited film can be
`larger than the area in which the deposition provides a film with uniform physical or optical
`properties such as chemical composition or index of refraction. In some embodiments,target 12
`is substantially planar in order to provide uniformity in the film deposited on substrate 16. In
`practice, planarity of target 12 can mean thatall portions ofthe target surface in region 52 are
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`within a few millimeters of a planar surface, and can be typically within 0.5 mm of a planar
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`surface.
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`[0069] Other approachesto providing a uniform condition of sputter erosion rely on creating a
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`large uniform magneticfield or a scanning magnetic field that produces a time-averaged,
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`Ex. 1052, Page 13
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`M-12245 US
`852923 vi
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`uniform magnetic field. For example, rotating magnets or electromagnets can be utilized to
`provide wide areas ofsubstantially uniform target erosion. For magnetically enhanced sputter
`deposition, a scanning magnet magnetron source can be used to provide a uniform, wide area
`condition of target erosion.
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`
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`[0070] As illustrated in FIG. 1A, apparatus 10 can include a scanning magnet magnetron source
`20 positioned above target 12. An embodiment of a scanning magnetron source used for de
`sputtering of metallic films is described in U. S. Patent No. 5,855,744 to Halsey,et. al.,
`(hereafter ‘744), whichis incorporated herein by reference in its entirety. The ‘744 patent
`demonstrates the improvement in thickness uniformity that is achieved by reducing local target
`erosion due to magnetic effects in the sputtering of a wide area rectangular target. Asdescribed
`in the ‘744 patent, by reducing the magnetic field intensity at these positions, the local target
`erosion was decreased andtheresulting film thickness nonuniformity was improved from 8%, to
`4%, over a rectangular substrate of 400 x 500 mm.
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`[0071] The process gas utilized in reactor 10 includes an inert gas, typically argon, used as the
`background sputtering gas. Additionally, with some embodiments of target 12, reactive
`components such as, for example, oxygen may be added to the sputtering gas. Other gasses such
`as N>, NH3, CO, NO, CO, halide containing gasses other gas-phase reactants can also be
`utilized. The deposition chambercan be operated at low pressure, often between about 5
`millitorr and 8-10 millitorr. Typical process pressure is below about 3-5millitorr where there are
`very few collisions in the gas phase, resulting in a condition of uniform “free molecular” flow.
`This ensures that the gas phase concentration of a gaseous componentis uniform throughout the
`process chamber. For example, background gas flow ratesin the range ofup to about 200 sccm,
`used with a pump operatedat a fixed pumping speed of about 50 liters/second, result in free
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`molecular flow conditions.
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`[0072] The distance d, in Figure 1A, between target 12 and substrate 16 can, in some
`embodiments, be varied between about 4 cm and about 9 cm.A typical target to substrate
`distance d is about 6 cm. Thetarget to substrate distance can be chosen to optimizethe thickness
`uniformity ofthe film. At large source to substrate distances the film thickness distributionis
`domeshaped with the thickest region ofthe film at the center of the substrate. At close source to
`substrate distance the film thicknessis dish shaped with the thickest film formed at the edge of
`the substrate. The substrate temperature can be held constantin the range of about -40 °C to
`-13-
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`Ex. 1052, Page 14
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`Ex. 1052, Page 14
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` Ex. 1052, Page 15
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`[0073] The speed at which a scanning magnet 20 can be sweptoverthe entire target can be
`determined suchthat a layer thickness less than about 5 to 10 A, corresponding roughly to two to
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`four monolayers of material, is deposited on each scan. Magnet 20 can be movedat rates up to
`about 30 sec/one-way scan and typically is movedat a rate of about 4 sec/one-way scan. The
`rate at which material is deposited depends on the applied power and on the distance d, in Figure
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`1A, between the target 12 and the substrate 16. For deposition of optical oxide materials, for
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`example scanning speeds between about 2 sec/one-way scan across the target to 20-30 sec/scan
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`provide a beneficial layer thickness. Limiting the amount of material deposited in each pass
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`promotes chemical and physical uniformity of the deposited layer.
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`[0074] Substrate bias has been used