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`UNITED STATES DEPARTMENT OF COMMERCE
`
`United States Patent and Trademark Office
`
`September 29, 2020
`
`THIS IS TO CERTIFY THAT ANNEXED HERETO IS A TRUE COPY FROM
`
`THE RECORDS OF THE UNITED STATES PATENT AND TRADEMARK
`
`OFFICE OF THOSE PAPERS OF THE BELOW IDENTIFIED PATENT
`
`APPLICATION THAT MET THE REQUIREMENTS TO BE GRANTED A
`FILING DATE UNDER 35 USC 111.
`
`APPLICATION NUMBER: 09/145,323
`
`FILING DATE: September 01, I 998
`
`THE COUNTRY CODE AND NUMBER OF YOUR PRIORITY
`
`APPLICATION, TO BE USED FOR FILING ABROAD UNDER THE PARIS
`
`CONVENTION, IS LEW/145,323
`
`‘
`
`
`
`By Authority of the
`
`Under Secretary of Commerce for Inteileetual Property
`and Director of the United States Patent and Trademark Office
`
`YEN NGO
`
`Certifying Officer
`
`
`
`
`Page 1 of 22
`Page 1 of 22
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`(cid:44)(cid:49)(cid:55)(cid:40)(cid:47) EXHIBIT 1060
`INTEL EXHIBIT 1060
`
`

`

`
`|'I_,.t|ll...”
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`Total Claims
`Inde - - ndent Claims
`
`
`
`I
`
`IN THE UNITED STATES
`5=3
`PATENT AND TRADELVLARK OFFICE
`=4
`%EzPATENT APPLICATION
`4am” m" mm
`
`EuRonald Eugene Miller
`ajhfflé
`=
`.
`'
`3 John 2. Pastalan
`E {3360rge E Rittenlrouse
`g 0
`CASE 1-1-1
`
`TITLE
`
`PuJSe DC Reactive Sputtering Method
`
`ASSISTANT COMIVIISSIONER FOR PATENTS
`WASHINGTON, DC. 20231
`
`SIR:
`
`Enclosed are the following papers relating to the above-named application for patent:
`
`NEW APPLICATION UNDER 37 CFR 1.53191
`
`Specification
`4 Infomal sheets of drawing(s)
`Information Disclosure Statement
`
`CLAIMS AS FILED
`
`Multiple Dependent
`C1ain1(s), if up I licable
`Basic Fee
`
`'I‘..llI!..|'FL.‘1
`!I.”itll"
`[rum
`
`Please file the application and charge Lucent Technologies Deposit Account No. 12-2325 the
`amount of $790, to cover the filing fee. Duplicate copies of this letter are enclosed. In the event
`of non-payment or improper payment of a required fee, the Commissioner is authorized to
`charge or to credit Deposit Account No. 12-2325 as required to correct the error:
`
`The Assistant Commissioner for Patents is hereby authorized to treat any concurrent or future re—
`ply, requiring a petition for extension of time under 37 CFR § 1.136 for its timely submission, as
`incorporating a petition for extension of time for the appropriate length of time if not submitted
`with the reply.
`
`(Room 3C-512),
`to Docket Administrator
`correspondence
`all
`address
`Please
`Lucent Technologies Inc., 600 Mountain Avenue, P. O. Box 636, Murray Hill, New Jersey
`07974-0636. However, telephone calls should be made to me at 908—582-3246.
`
`Respectfully.
`PW’M’L
`J nM.Harman
`
`Reg. No. 38173
`Attorney for Applicant(s)
`
`[ iii S
`i.
`"T
`Date:
`Lucent Technologies Inc.
`600 Mountain Avenue
`P. 0. Box 636
`Murray Hill, New Jersey 07974-0636
`
`PT 13 12’97
`
`Page 2 of 22
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`Miller 1—1-1
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`PULSE DC REACTIVE SPUTTERING METHOD
`
`FOR FABRICATING PIEZOELECTRIC RESONATORS
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`Backgroggd of the Invention
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`1. Field of the invention
`
`10
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`15
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`20,
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`25
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`The invention relates to piezoelectric resonators. More particularly, the invention
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`relates to deposition techniques used in fabricating piezoelectric resonators and the
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`piezoelectric resonators made by those deposition techniques.
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`2. Qgcription of the Related Art
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`Piezoelectric resonators are devices comprising a wafer of piezoelectric material
`
`such as quartz, zinc oxide (2110), aluminum nitride (AlN) or ceramic material mounted or
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`otherwise formed on a substrate (e.g., silicon or aluminum oxide). Upon the application
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`of a voltage to the piezoelectric material, e.g., via electrodes, the piezoclectric material
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`vibrates in a certain vibrational mode depending on the orientation or polarization of the
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`piezoelectric material and at a certain (resonant) frequency depending on the thickness of
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`the piezoelectric material.
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`Piezoelectric resonators provide clearly defined mechanical resonances and are
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`useful, e.g., for discriminating between signals based on frequency diversity (i.e., a filter).
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`Also, piezoelectric resonators are useful in providing stable frequency signals, e.g., as a
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`fi-equency stabilizing feedback element in an oscillator circuit.
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`Typically. the resenant frequency of the piezoelectric material is inversely
`
`proportional to its thickness. Accordingly. for piezoelectric resonators to operate at high
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`frequencies, e.g., frequencies greater than approximately 700 Megahertz (MHz), the
`thickness of the piezoelectric material must be reduced to the point of depositing a thin
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`piezoelectric film on the substrate. Conventional deposition techniques for depositing
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`such piezoelectric films include, e.g., chemical vapor deposition (CVD) and sputter
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`deposition such as RF sputter deposition.
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`Miller l-I~1
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`Spotter deposition involves a vacuum deposition process in which a sputtering
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`target is bombarded with ions, typically an ionized noble gas such as argon, and the atoms
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`of the target material are mechanically freed by momentum transfer and available for
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`coating a nearby substrate. Suitable target materials include, e.g., aluminum, silicon and
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`5
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`titanium In a reactive Sputtering process, a reactive gas is introduced into the deposition
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`chamber and reacts with the target material to produce a target insulating film that
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`subsequently is sputtered onto the substrate or reacts with freed target material to form a
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`coating material that is sputtered onto the substrate. Suitable reactive gases include
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`oxygen, nitrogen, ammonia and hydrogen.
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`10
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`In DC reactive sputtering, the target material and the reactive gas react in a plasma
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`to produce the coating material The plasma is formed by the noble gas when an direct
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`current (DC) electric potential is applied within the sputtering chamber. For example,
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`aluminum atoms from an aluminum target react with nitrogen (reactive gas) at the target
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`to produce an insulating film of aluminum nitride (AlN), which is Sputtered onto the
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`15
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`substrate with ions of argon (noble gas). Other suitable coatings include, e.g., oxides
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`such as aluminum oxide (A1203), carbides such as silicon carbide (81C), and nitrides such
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`as titanium nitride (TEN) or zinc oxide (ZnO).
`However. sputter deposition and reactive sputtering techniques including DC
`reactive sputtering often do not provide adequate deposition rates. Accordingly, such
`techniques take longer to perform, which is undesirable from the standpoint of required
`
`20
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`processing time and ultimately is undesirable from an economic standpoint. Also. the
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`relatively lengthy deposition period increases the introduction of impurities into the
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`piezoelectric film being deposited
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`One specific type of reactive sputtering that ofien is used in. e.g., silicon
`
`25
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`processing methods, is pulse DC reactive sputtering. Since the target insulating film is an
`
`insulator (e.g., AIN), the noble gas ions tend to accumulate on its surface, reducing the
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`sputter rate and ultimately terminating the sputter process. In pulse DC reactive
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`sputtering. the electric potential formed between the cathode and the anode in the
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`chamber is reversed periodically to prevent charge accumulation on the target insulating
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`30
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`film. More specifically, the positive portion of the applied voltage neutralizes
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`Miller 1-1-1
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`accumulation of the noble gas ions on the surface of the target insulating film, and the
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`negative portiou of the applied voltage, if sufficient, canses ions from the noble gas to
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`impinge upon the target insulating film formed on the target material, physically
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`removing ions thereof and allowing them to accumulate on the substrate. This forms the
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`deposited layer or coating.
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`In addition to silicon processing, pulse DC reactive Sputtering techniques also are
`
`useful in depositing, e.g., wear resistant coatings such as tungsten carbide (WC) or
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`titanium nitride (T1N) 0n, e.g., drill bits, wear plates and valve spindles. See generally,
`
`e.g., U.S. Pat. Nos. 5,651,865 and 5,718,813. In pulse DC reactive sputtering. the major
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`qualitative concerns are the ultimate film constituency (i.e., reduced impurities introduced
`
`into the deposited film), film stress and film texture. Film texture generally characterizes
`
`the physical structure of the film resulting from the shape, arrangement and proportions of
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`its components.
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`With respect to the deposition of thin piezoelectric films such as aluminum nitride
`
`(AIN), an important consideration includes the crystal orientation of the atoms within the
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`final deposited film That is, the crystal structure cannot be amorphous; it must be of a
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`single crystal nature. This is because piezoelectricity occurs from the alignment of the
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`atomic dipoles within the film, and an amorphous film produces random dipole moments
`
`with no macroscopic response. Also. it is desired that the film orientation be
`
`perpendicular to the substrate to facilitate the launching of longitudinal waves in a
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`structure. It is believed that current deposition techniques are concerned primarily with
`
`deposition rates and consideration such as crystal structure are not taken into account.
`
`Accordingly, it is desirable to have available an improved technique for
`
`depositing thin films of piezoelectric material such as aluminum nitride (MN) on a
`
`substrate that provides piezoelectric films with improved control of film constituency,
`
`10
`
`15
`
`a
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`stress and texture.
`
`So
`
`the Invention
`
`The invention is embodied in a pulse DC reactive sputtering method for thin film
`
`deposition. The inventive method is used, e.g., for depositing thin films of piezoelectric
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`Miller 1-1-1
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`10
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`20
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`materials such as aluminum nitride on substrates with patterned electrodes during the
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`fabrication of piezoelectric resonators. Embodiments of the invention include the steps of
`
`providing a target material such as aluminum within the sputtering chamber, positioning a
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`substrate such as silicon within the sputtering chamber, providing a noble gas such as
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`argon into the Sputtering chamber. directing a reactive gas such as nitrogen within the
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`sputtering chamber, applying a pulsed DC voltage across the electrodes within the
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`Sputtering chamber sufficient to cause ions from the noble gas to impinge upon the thin
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`insulating layer (e.g., AlN) formed on the target material, physically removing ions
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`thereof and allowing them to accumulate on the substrate. According to embodiments of
`
`the invention, the pulse width of the positive portion of the applied voltage is adjusted
`
`based on its effect on the desired film constituency, stress, and texture. By comparison,
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`conventional arrangements establish pulse widths based on their effect on improving
`
`deposition rates, regardless of its effect on the film texture. Alternatively, embodiments
`
`of the invention adjust the direction and delivery of the reactive gas within the sputtering
`
`chamber, e. g., toward the target material, to further enhance the desired film constituency,
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`stress, and texture through more efficient reaction by the reactive gas.
`
`Brief Desgflg'1:ng of the Drilling
`
`In the drawings:
`
`Figs. la-b are simplified side, cross-sectional views of non-via, Bragg reflection
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`piezoelectric resonators;
`
`Fig. 2 is a simplified schematic diagram of a pulse DC reactive sputtering '
`
`arrangement;
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`Fig. 3 is a simplified block diagram of a method for fabricating piezoelectric
`
`resonators according to embodiments of the invention;
`
`Fig. 4a is a graphical diagram of the voltage applied to the electrodes of a pulsed
`
`DC reactive sputtering arrangement according to an embodiment of the invention; and
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`Fig. 4b is a graphical diagram of the voltage applied to the electrodes of a
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`conventional pulsed DC reactive Sputtering arrangement.
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`l
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`Miller 1-1-1
`
`Detailed Description
`
`Although specific features, configurations and arrangements are discussed
`
`hereinbelow, it should be understood that such is done for illustrative purposes only. A
`
`person skilled in the relevant art will recognize that other steps. configurations and
`
`arrangements are useful without departing from the spirit and scope of the invention.
`
`Embodiments of the invention include piezoelectric resonators with improved
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`piezoelectric film quality and control of methods for making such piezoelectric resonators
`
`using pulse DC reactive sputtering for the deposition of thin films of piezoelectric
`
`material on substrates. Embodiments of the invention are based on the realization that
`
`varying or adjusting the pulse width of the positive portion of the applied DC voltage
`
`improves the control and crystallinity of the deposited piezoelectric material.
`
`Alternatively, adjusting the direction and delivery of the reactive gas within the sputtering
`
`chamber further enhances such desired results. Typically, such adjustments are at the
`
`expense of deposition rate. which drives conventional pulse DC- rcactive sputtering
`
`techniques. However, increased deposition rates, in general, produce metal-rich films
`
`that degrade the crystalline structure of the deposited piezoelectric material.
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`Referring now to Fig. 1a, a simplified diagram of a piezoelectric resonator 100 is
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`shown. The piezoeiectric resonator 100 comprises a substrate 110, a layer or body 120 of
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`piezoelectric material, and an acoustic reflecting region 125 such as a Bragg reflecting
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`region therebetween. Alternatively. as shown in Fig. lb, the layer 120 of piezoelectric
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`material is suspended above the substrate 110 by a suspended membrane 127 of, e.g.. air
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`or silicon nitride (SiNx). A pair of electrodes 130, 135 are coupled or otherwise attached
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`to piezoelectric material 120 of both arrangements, e.g., by conventional means.
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`The layer 120 of piezoelectric material is made of any suitable material that has
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`piezoelectric qualifies sufficient for the particular resonator application. Typical
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`piezoelectric materials include, e.g., quartz, zinc oxide (ZnO), aluminum nitride (MN)
`
`and ceramic materials such as lithium niobate (LiNbOg), lithium tantalate (LiTa03),
`
`paratellurite (T602) and lead titanate zirconate (PZ'I'~SA). The substrate 110 is made of.
`
`e.g., silicon (Si), aluminum oxide (A1203) or other suitable materials such as quartz,
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`sapphire, polysilicon and aerogei.
`
`
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`Miller 144
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`In use, the piezoelectric resonator 100 typically has a voltage potential applied
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`across electrode 130, 135, which causes the layer 120 of piezoelectric material to vibrate
`
`at a resonant frequency,fl), due to the piezoelectric effect, thus Operating as a resonator.
`
`The operating frequency of the piezoelectric resonator 100 depends on the total thickness
`
`of the pieZDelectr-ic layer 120 and the electrodes 130, 135, which total thickness is due
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`mostly to the thickness of the piezoelectric layer 120. More specifically, the operating
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`frequency is inversely proportional to the thickness of the piezoelectric layer 120 and the
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`electrodes 130, 135. Accordingly, for high operating frequencies, e.g., frequencies
`
`greater than approximately 700 Megahertz (MHz), the thickness of the piezoelectric layer
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`129 has been reduced to the extent that the piezoelectric layer 120 is merely a thin film
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`deposited on the substrate 110. Typical thicknesses of the piezoelectric film range from
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`approximately five hundred (500) nanometers (run) to approximately ten (10) microns
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`(pm).
`
`As discussed previously herein, conventional sputtering techniques such as sputter
`
`deposition, reactive sputter deposition, and DC reactive sputtering do not provide
`
`adequate deposition rates. However, one type of conventional sputtering technique that
`
`often provides an adequate deposition rate is pulse DC reactive sputtering. Referring now
`
`to Fig. 2, a typical pulse DC reactive sputtering arrangement 200 is shown.
`
`10
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`15
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`..h|dItllII
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`The conventional arrangement 200 includes a chamber 210 (e.g., a plasma
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`20‘
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`chamber) and a pair of electrodes 220, 225 configured within the chamber 210. The
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`electrodes 220, 225 are capable of supplying an electric potential therebetween, as
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`indicated generally by the polarity signs associated therewith. The electric potential
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`applied to the electrodes is controlled, e.g., by any suitable control means (shown
`
`generally as 230), including pulse width control.
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`The arrangement 200 includes a first source 240 capable of supplying a noble gas,
`e.g., argon (Ar), into the chamber 210. Other suitable noble gases include, e.g., 'xenon
`
`(Xe) and krypton (Kr). Also, the arrangement 200 includes a second source 250 capable
`
`of supplying a reactive gas into the chamber 210, e.g., via a gas delivery ring 255. The
`
`reactive gas is. e.g., oxygen, nitrogen or other suitable gas.
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`Miller 1-1-1
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`A (conductive) target 260 is positioned within the chamber 210, e.g., in electrical
`
`connection with one of the two electrodes 220. In this manner, the target 260 serves as
`
`the cathode during the sputter portion of the cycle when a negative electrical potential is
`
`applied across electrodes 220, 225. The target 260 is, e.g., a relatively flat plate of
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`5
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`aluminum or other suitable material such as zinc.
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`The substrate 110 upon which the piezoelectric thin film is to be coated is
`
`positioned within the chamber 210, e.g., above the target 260 and the gas delivery ring
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`255. The substrate 110 is made of, e.g., silicon, aluminum oxide (M203) or other suitable
`
`material such as quartz, sapphire, polysilicon and aerogel.
`
`to
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`In operation, the first source 240 provides noble gas into the chamber 210. A
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`second source 250 delivers reactive gas into the sputtering chamber 210. According to
`
`embodiments of the invention, the gas delivery ring 255 directs the delivery of the
`
`reactive gas at the target 260 (as will be discussed in greater detail hereinbelow). The
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`reactive gas produces a relatively thin insulating film (e.g., AlN) on the target 260. Upon
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`15
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`the application of a sufficient electric potential across the electrodes 220, 225, ionization
`
`of the noble gas occurs and ions therefrom sputter the thin nitride film on the target 260.
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`Atoms of the nitride film on the target 260 are freed by the ion bombardment and thus are
`
`made available for coating the substrate 110.
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`Pulsed DC reactive sputtering arrangements offer an additional variation to the
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`20
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`arrangement described in that the electric potential supplied between the electrodes
`
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`includes a positive voltage pulse. Conventionally, the voltage is pulsed, e. g., to reduce
`
`the possibility of arching (see, e.g., U.S. Patent No. 5,651,865) and to prevent excessive
`
`accumulation of noble gas ions on the surface of the target material. However, according
`
`to embodiments of the invention, the pulse yields an extra degree of freedom in the fihn
`
`25
`
`deposition to improve the film quality and reproducibility.
`
`For example, conventional pulse DC reactive sputtering arrangements supply a
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`positive DC voltage of approximately 50 volts typically for approximately 25% of the
`
`duty cycle and then a negative DC voltage of approximately 200-500 volts for remaining
`
`75% of the duty cycle. The duty cycle ratio of positive DC voltage to negative DC
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`30
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`voltage conventional is adjusted based on the effect it has on deposition rate and noble
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`Miller 1-1-1
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`rl||
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`:
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`gas ion accumulation. As mentioned previously herein, the amplitude and pulse width of
`
`the applied DC voltage is controlled, e.g., by any suitable control means (shown generally
`
`as 230).
`
`However, the conventional desire to neutralize accumulated charge on the target
`
`5
`
`film and maximum deposition rate results in a film that is slightly metal-rich. This
`
`stoichiometry produces a relatively poor film texture. Therefore, according to
`
`embodiments of the invention, the pulse width is adjusted to produce a stoichiomeuy that
`
`improves the film texture.
`
`1n pulse DC reactive sputtering systems, whether it be in silicon processing or in
`
`10
`
`fabricating piezoelectric resonators, other variables also are managed in an attempt to
`
`improve the deposition rate and the overall quality of the deposited films without
`
`sacrificing too much from either. Such variables include, e.g., substrate temperature,
`
`substrate bias, deposition, gas ratio and chamber pressure. However, just as with the
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`pulse width, many of these variables are advantageous to one aspect and simultaneously
`
`15
`
`are disadvantageous to another aspect. Therefore, many of the variables often are
`
`adjusted with such considerations in mind and, accordingly, are set in a manner that
`
`amounts to a compromise between the two conflicting aspects. In general, the more
`
`important variables are chamber pressure, reactive gas delivery, deposition power and gas
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`ratio.
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`20
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`Embodiments of the invention are based on the realization that adjusting the pulse
`
`width of the positive portion of the applied DC voltage significantly increases the film
`
`texture for a given range of other deposition parameters. Furthermore, providing a gas
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`delivery system that directs the reactive gas directly to the active sputter area further
`
`enhances the film texture. Accordingly, embodiments of the invention offer piezoelectric
`
`25
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`resonators having thin films of piezoelectric material with improved texture compared to
`
`similarly deposited films without the inventive pulse width adjustments and gas delivery.
`
`Fig. 3 shows generally a. method 300 for fabricating a piezoelectric resonator
`
`according to embodiments of the invention. Reference will be made periodically to the
`
`pulse DC reactive sputtering arrangement 200 shown in Fig. 2 during the discussion
`
`30
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`hereinbelow of the method 300. However, it should be remembered that the exemplary
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`Miller 1-1-1
`
`method 300 shown in Fig. 3 and the pulse DC reactive sputtering arrangement 200 shown
`
`in Fig. 2 are for illustration purposes only and are not meant to be a limitation of the
`
`invention.
`
`The first step 310 of the inventive method 300 is to provide the target material
`
`5
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`260 for use within the sputtering chamber 210 suitable for use in pulse DC reactive
`
`sputtering techniques. As discussed previously herein, the target material is, e.g.,
`
`aluminum, zinc or other suitable (conductive) material. The next step 320 is to provide or
`
`otherwise position the substrate 110 within the sputtering chamber 210. The substrate
`
`110 is positioned within the chamber 210, e.g., above the target 260. The substrate is
`
`10 made of, e.g., silicon, aluminum oxide (A1203) or other suitable material such as quartz,
`
`sapphire, polysilieon and aerogel.
`
`The next step 330 is to introduce a noble gas (e.g., via the first source 240) into
`
`the sputtering chamber 210. The next step 350 is to introduce the reactive gas into the
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`sputtering chamber 210. According to embodiments of the invention, the reactive gas is
`
`15
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`directed onto the target 260, e.g., by the gas delivery ring 255. The next step 340 is to
`
`apply a sufficient electrical potential across the electrodes 220, 225 to cause ions of the
`
`noble to be directed toward the target 260 along with reactive gas with sufficient energy
`
`to cause atoms of the target material and the insulating layer formed on the target 260 to
`
`be released from the target 260. The next step 360 is to adjust the pulse width to
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`20
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`neutralize the accumulated charge on the surface of the target 260. As discussed
`
`previously herein, the reactive gas forms a thin film on the surface of the target 260,
`
`which is released and, in turn, coats the substrate and forms a layer thereon.
`
`As discussed previously herein, pulse DC reactive sputtering arrangements
`
`provide a periodic positive DC voltage across the electrodes 220, 225 separated by
`
`25
`
`periods in which a negative voltage potential exists across the electrodes and target
`
`sputtering occurs. The application of this periodic positive voltage pulse is done for a
`
`number of reasons, as discussed hereinabove, including to improve film texture and
`
`increase piezoelectric response.
`
`According to embodiments of the invention, the method 300 includes an adjusting
`
`30
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`step 360 to adjust the pulse width of the applied periodic DC pulses for purposes of
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`improving the crystalline quality of the coating or layer. The pulse width and other
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`parameters associated with the applied voltage signal are controlled, e.g., by a control
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`means 230, shown generally in Fig. 2.
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`According to embodiments of the invention, in general, with a given set of
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`5
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`deposition parameters, adjusting the pulse width and directing the gas components to the
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`active Sputtering region on the surface of the target 260 improve the film texture of the
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`final deposited layer. According to embodiments of the invention, the pulse width of the
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`positive portion of the pulsed DC voltage is adjusted to be within the range from
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`approximately 540% of the pulsed DC voltage duty cycle.
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`10
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`By comparison, conventional pulsed DC reactive sputtering arrangements often
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`establish pulse widths based on increasing or maximizing deposition rates, with little if
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`any regard for the crystalline quality of the deposited layer that ultimately is formed on
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`the substrate. Conventional pulse widths typically are set to no more than approximately
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`25% of the duty cycle and typically remain at or near 25% of the duty cycle.
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`15
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`Figs. 4a—b illustrate the voltage applied between the electrodes in pulsed DC
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`reactive sputtering arrangements according to embodiments of the invention (Fig. 4a) and
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`according to conventional configurations (Fig. 41)). As shown in Fig. 4a, the applied
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`voltage pulses according to embodiments of the invention typically are less than 25% of
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`the duty cycle, which is smaller than the applied voltage pulses in conventional
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`MO
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`arrangements, as shown in Fig. 4b.
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`According to embodiments of the invention, regions of piezoelectric material are
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`formed that have full width at half maximum (FWHM) rocking curves of less than
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`approximately 2.5, but typically within the range from approximately 1.8 to 2.5. By
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`comparison, conventional methods produce piezoelectric materials that have full width at
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`25
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`half maximum rocking curves of at least 2.5, more typically within the range from
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`approximately 3 to 5.
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`It will be apparent to those skilled in the art that many changes and substitutions
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`can he made to the embodiments of the piezoelectric resonators deposition techniques
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`herein described without departing from the spirit and scope of the invention as defined
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`30
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`by the appended claims and their full scope of equivalents.
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`WHAT lS CLAilViED IS:
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`1. A method of pulse DC reactive sputtering, said method comprising the steps
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`of:
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`providing a target material within a sputtering chamber;
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`positioning a substrate within said sputtering chamber;
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`introducing a noble gas into said sputtering chamber;
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`introducing a reactive gas into said sputtering chamber, wherein said reactive gas
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`reacts with a portion of said target material to form an insulating film on said target
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`material;
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`applying a pulsed DC voltage across a pair of electrodes that are positioned within
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`said sputtering chamber in such a way that ions from said noble gas impinge upon the
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`target material and the insulating layer formed on said target material, wherein the freed
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`atoms of the target material and the insulating layer are available for accumulation on said
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`substrate to form a coating thereon; and
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`adjusting the pulse width of said pulsed DC voltage to improve the crystalline
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`structure of the coating formed on said substrate.
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`2. The method as recited in claim 1, wherein the pulsed DC voltage includes a
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`positive portion and a negative portion, and wherein said adjusting step adjusts the
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`positive portion of the pulsed DC voltage to be within the range from approximately 5—
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`40% of the pulsed DC voltage duty cycle.
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`3. The method as recited in claim 1, further comprising the step of directing said
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`reactive gas toward said target material within said sputtering chamber.
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`4. The method as recited in claim 1, wherein the pulsed DC voltage includes a
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`positive portion and a negative portion, and wherein said applying step further comprises
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`10
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`11
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`12
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`13
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`15
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`AW'N
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`Miller 1-1-1
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`applying the positive portion of the pulsed DC voltage sufficient to limit the
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`accumulation of ions of said noble gas on said target material.
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`5. The method as recited in claim 1, wherein said reactive gas is selected from the
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`group consisting of nitrogen, oxygen, ammonia and hydrogen.
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`6. The method as recited in claim 1, wherein said target material is selected from
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`the group consisting of aluminum, quartz, zinc oxide (ZnO), aluminum nitride (AIN),
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`lithium niobate (LiNbOg), lithium tantalate (LiTa03), parateliurite (Teog) and lead
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`titanate zirconate (PZT-SA).
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`7. The method as recited in claim 1, wherein said noble gas is selected from the
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`group consisting of argon (Ar), xenon {Xe} and krypton (Kr).
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`8. The method as recited in claim 1, wherein said substrate is selected from the
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`group consisting of silicon, aluminum oxide (A1203), quartz, sapphire, polysilicon and
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`aerogel.
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`9. A method of making a piezoelectric resonator, said method comprising the
`steps of:
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`providing a sputtering chamber including a target material;
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`positioning a substrate within said sputtering chamber;
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`introducing a noble gas into said sputtering chamber;
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`directing a reactive gas within said sputtering chamber toward the target material.
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`wherein said reactive gas reacts with a portion of said target material to form an
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`insulating film on said target material;
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`applying a pulSed DC voltage across a pair of electrodes that are positioned within
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`said sputtering chamber in such a way that ions from said noble gas impinge upon the
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`target material and the insulating layer formed on said target material, wherein the freed
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`4
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`3
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`4
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`5
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`6
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`7
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`9
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`12
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`atoms of the target material and the insulating layer are available for accumulation on said
`
`substrate to form a coating thereon; and
`
`adjusting the pulse width of said pulsed DC voltage to improve the crystalline
`
`structure of the coating formed on said substrate.
`
`10. The method as recited in claim 9, wherein said adjusting step adjusts the
`
`pulse width of the positive portion of the pulsed DC voltage to be within approximately
`
`540% of the duty cycle.
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`11. The method as recited in claim 9, wherein said target material is selected
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`from the group consisting of aluminum. quartz. zinc oxide (ZnO), aluminum nitride
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`(MN), lithium uiobate (LiNbOg), lithium tantalate (LiTa03lr Paratellurite (TeOz) and lead
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`titanate zirconate (PET—SA).
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`12. The method as recited in claim 9, wherein said reactive gas is selected from
`
`the group consisting of nitrogen, oxygen, ammonia and hydrogen.
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`13. The method as recited in claim 9, wherein said noble gas is selected from the
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`group consisting of argon (Ar), xenon (Xe) and krypton (Kr).
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`14. The method as recited in claim 9, wherein said substrate is selected from the
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`group consisting of silicon, aluminum ox