Patent Application
20170260618
Field
Implementations of the present disclosure generally relate to forming protective layers on mechanical components, and more particularly, to electro-chemically forming coating such as yttria or yttrium oxide on semiconductor processing equipment.
Description of the Related Art
Conventionally, semiconductor processing equipment surfaces include certain coatings thereon to provide a degree of protection from the corrosive processing environment or to promote surface protection of the equipment. Several conventional methods utilized to coat the protective layer include physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma spraying, aerosol deposition, and the like. However, these conventional methods are unable to satisfactorily coat semiconductor equipment, especially in areas having small holes or plenums, such as showerheads.
Therefore, there is a need for improved deposition methods for protective coatings.
In one implementation, a method of depositing a material on a substrate comprises positioning an aluminum substrate in an electroplating bath, the electroplating bath comprising a non-aqueous solvent and a deposition precursor, depositing a coating on the aluminum substrate, the coating comprising yttria, removing excess plating solution form the aluminum substrate, and post-treating the aluminum substrate having the coating thereon.
In another implementation, a method of depositing a material on a substrate comprises positioning an aluminum substrate having one or more plenums formed therein in an electroplating bath, the electroplating bath comprising a non-aqueous solvent and a deposition precursor, the deposition precursor comprising YCl3 or Y(NO3)3, depositing a coating on the aluminum substrate, the coating comprising yttria or yttria oxide, removing excess plating solution form the aluminum substrate, wherein the removing comprises washing the aluminum substrate and drying the aluminum substrate with compressed dry air, and post-treating the aluminum substrate having the coating thereon.
In another implementation, a method of depositing a material on a substrate comprises positioning an aluminum substrate having one or more plenums formed therein in an electroplating bath, the electroplating bath comprising an aqueous solvent and a deposition precursor, depositing a coating on the aluminum substrate, the coating comprising yttria or yttria oxide; removing excess plating solution form the aluminum substrate, and post-treating the aluminum substrate having the coating thereon.
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 exemplary implementations and are therefore not to be considered limiting of its scope, and the disclosure may admit to other equally effective implementations.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one implementation may be beneficially incorporated in other implementations without further recitation.
The present disclosure generally relates to methods of electro-chemically forming yttria. The methods may include the optional preparation of a an electrochemical bath, the electrodepositon of yttria onto a substrate, removal of solvent form the surface of the substrate, and post treatment of the substrate having the electrodeposited yttria thereon.
The method 100 begins at operation 101. In operation 101, an electrochemical bath 210 is prepared. The electrochemical bath 210 includes a container 211 having a solution 212 disposed therein. The solution 212 may include one or more of a solvent, an electrolyte or other deposition precursor, and plating additives. The solution may be conductive to facilitate electrochemical deposition. An anode 213 and a substrate 214, which functions as a cathode, are positioned in the solution 212 and may be separated by a divider 215, such as a perforated sheet. The perforated sheet may be polypropylene or polytetrafluoroethylene having a plurality of openings therein. The openings may have a diameter of about 0.025 inches, and a density of 5 openings or less per square centimeter. The anode 213 and the substrate 214 are coupled to a power supply 216, such as a DC power supply, to facilitate plating of material onto the substrate 214. Power may be supplied at a constant current or voltage, or a pulsed current or voltage. In one example, the substrate 214 is semiconductor processing equipment. Examples of semiconductor processing equipment include components formed from aluminum or aluminum alloys, such as showerheads or gas distributors, or other equipment which may have a plurality of gas passages formed therein. Examples of aluminum alloys include Al6061 and Al6063, among other alloys. It is contemplated that substrates without gas passages formed therein may also be subjected to plating. In one example, the anode 213 may also be formed from aluminum, such as Al6061 aluminum alloy.
The solution may 212 may include one or more aqueous solvents such as water, or non-aqueous solvents such as dry acetonitrile, ethanol, toluene, or isopropyl alcohol. One or more plating precursors, such as YCl3, Y(NO3)3, yttrium acetate, or organometallic precursors such as Y—(CxHy)z, may be dissolved in the solution 212. In the example of Y—(CxHy)z, z may, but need not, be equal to x. The one or more plating precursors may be dissolved in the solution at a concentration of about 0.001 Molar (M) to about 2M, such as about 0.1M to about 1M, for example, about 0.5M to about 1M. One or more additives, such as potassium nitrate (KNO3), sodium fluoride, sodium acetate, and tetrabutul ammonium hexaflurophosphate may be added to the solution 212 to improve characteristics of the plated material. For example, the additives may be selected to improve planarity of the deposited coating, adjust composition of deposited coating, or to reduce roughness or cracking of the plated coating. Additives may also be selected to improve the conductivity of the solution 212, thereby increasing deposition rate of the plated material and improving deposition uniformity. The one or more additives may be present in the solution 212 at a concentration of 0.001 Molar (M) to about 1M, such as about 0.1M to about 0.5M, for example, about 0.1M to about 0.3M. The substrate 214 may be positioned in the solution 212 after preparation thereof.
In operation 102, a material, such as yttria, is electrodeposited on the substrate 214. The anode 213 is negatively biased by the power supply 216, while the substrate 214 is positively biased by the power supply 216. Bias of the anode 213 and the substrate 214 facilities plating of desired materials, such as yttria from the solution 212 on to the substrate 214. The anode 213 and the substrate 214 may be biased with a voltage in the range of about 1 volt to about 300 volts, such as about 1 volt to about 50 volts, or about 1 volt to about 10 volts. The anode 213 and the substrate 214 may be biased with a current in the range of about −0.1 milliampere to about −2 ampere, such as about −0.1 milliampere to about −50 milliampere, or about −0.1 milliampere to about −10 −0.1 milliampere. The solution 212 may be maintained at a temperature within a range of about 0 degrees Celsius to about 100 degrees Celsius during operation 102. In one example, the solution may be maintained at a temperature of about 10 degrees Celsius to about 50 degrees Celsius, such as about 25 degrees Celsius. The bias voltages of operation 102 may be applied for a time period of about 3 hours or less, for examples, about 5 minutes to about 60 minutes, such as about 10 minutes to about 30 minutes.
Additionally or alternatively, the use of pulse deposition techniques, where the potential or current is altered rapidly between two different values, is contemplated. The rapid alternation results in a series of pulses of equal amplitude, duration, and polarity, separated by zero current. Each pulse consists of an ON time (TON) and OFF time (TOFF). During TOFF, ions migrate to the depleted areas in the bath. During TON, more evenly-distributed ions are available for deposition onto the substrate 214. In one example, TON may be about 0.001 seconds to 60 seconds, and TOFF time may be about 0.001 seconds to 60 seconds.
It is contemplated that characteristics of operations 101 and 102 may be varied to achieve a desired thickness or composition of the plated material. For example, it is contemplated that the concentration of the plating precursor, the duration of the bias voltage, or the magnitude of the bias voltage may be increased in order to increase the deposition rate or the thickness of the plated material. In one example, the plated material, such as yttria, may be deposited to a thickness of about 3 nanometers to about 8 micrometers, such as about 10 nanometers to about 500 nanometers, for example, about 200 to about 400 nanometers. In another implementation, the plated material may be deposited to a thickness of about 1 micrometer to about 50 micrometers. In another example, it is contemplated that operation 102 may occur in an inert environment, such as in an argon or diatomic nitrogen environment. In another implementation it is contemplated that the solution 212 may be stirred during operation 102.
Subsequently, in operation 103, the substrate 214 is removed from the solution 212, and excess solution 212 is removed from the surface of the substrate 214. Excess solution 212 may be removed, for example, via evaporation or drying. One or more of a dryer, hear source, light source, or a fan may facilitate the removal of the excess solution 212 from the substrate 214. Additionally or alternative, the substrate 214 may be cleaned with ethanol or isopropyl alcohol, and then cleaned with compressed dry air, during operation 103.
In one plating example, the electrochemical deposition of yttria on the substrate 214 proceeds as follows:
Y3+2H++3e−=Y+H2
4OH−→2O−+2H2O+4e−
In operation 104, after evaporation of the excess solution 212, the substrate 214 may be subjected to a post treatment process. In one example, the post treatment process of operation 104 is an annealing process. In such an example, the substrate 214 may be annealed at a temperature of about 400 degrees Celsius or more. The anneal temperature may be selected to facilitate removal of hydroxyl moieties from the surface of the substrate 214 during the post treatment process. In another implementation, the post treatment process may be an oxidizing process. In such an example, the substrate 214 may be exposed to an oxygen-containing environment to facilitate oxidation of the plated material on the substrate 214. For example, the substrate may be exposed to oxygen, ozone, or ionized oxygen or oxygen-containing gas. The oxidation of the plated material may be facilitated through the use of plasma or thermal processing. The annealing process of operation 104 may also increase adhesion of the plated material to the underlying substrate 214. It is contemplated that different oxidation techniques, as well is different oxidation sources, may affect qualities of the film, including density, roughness, and oxygen content.
In another example, the post-treatment process may be a second bath. In the second bath, the substrate 214 may be anodized using neutral electrolytes at about 10 volts to about 200 volts to form an oxide layer on an outer surface of the plated coating. In another implementation, the post-treatment process may include exposing the substrate to nitric acid to oxidize the upper surface of the deposited coating. The nitric acid bath may include about 20% to about 69% nitric acid, and may be at a temperature of about 0 degrees Celsius to about 25 degrees Celsius. It is contemplated that temperatures below room temperature increase the density of the anodized layer compared to a similar nitric acid anodization process which occurs at room temperature or greater. In one example, the oxidized portion of the plated coating may have a thickness of about 200 nanometers or less, such as about 100 nanometers or less, such as about 5 nanometers or less. In one example, about 5 percent to about 5 percent of the plated aluminum layer may be anodized.
In one example, a coating is deposited on an aluminum substrate according to method 100. In the example, an aluminum substrate is positioned in an electroplating bath using ethanol as a solvent and having a deposition precursor dissolved therein at a concentration of 0.1M. The bath is maintained at a temperature of 10 degrees Celsius, and a bias of 10 volts is applied for 30 minutes. The film is then exposed to an oxidation process. The film has a composition of yttria within a range of about 14 atomic percent to about 47 atomic percent; a composition of aluminum in a range or about 2 atomic percent to about 3 atomic percent, and concentration of oxygen in a range of about 50 atomic percent to about 83 atomic percent.
In another example, an aluminum substrate is positioned in an electroplating bath using ethanol as a solvent and having a deposition precursor dissolved therein at a concentration of 0.1M. The bath is maintained at a temperature of 10 degrees Celsius, and a bias of 50 volts is applied for 30 minutes. The film is then exposed to an oxidizing process. The film has a composition of yttria within a range of about 12 atomic percent to about 43 atomic percent; a composition of aluminum in a range or about 9 atomic percent to about 10 atomic percent, and concentration of oxygen in a range of about 35 atomic percent to about 55 atomic percent.
While implementations described herein are directed to the deposition of yttria and yttria oxide, it is contemplated that other material may be plated. For example, it is contemplated that rare earth metal salts, cesium, lanthanum, and oxides thereof may be plated. It is contemplated that alternating layers of one or more materials may be plated, such as yttrium oxide and cesium oxide.
Benefits of the disclosure include more complete deposition of material on components, as well as crack free, uniform, dense oxide coatings. In contrast to conventional deposition techniques, the electroplating methods disclosed herein result in improved plating near orifices, plenums, or other small features of a substrate. The move complete coverage results in increased protection of the component, particularly in plasma environments often used in the processing of semiconductor materials.
Additionally, the anodized layers formed herein are more dense (e.g., less porous) than conventional anodization layers, thus providing better corrosion resistance, particularly to plasmas. In some examples, anodized layers of the present disclosure are subjected to a bath of 5 percent HCl in a bubble test. The anodization layer showed HCl bubble test resistance for about 20-47 hours. In contrast, conventional anodized layers show HCl bubble test resistance for about 5 hours.
While the foregoing is directed to implementations of the present disclosure, other and further implementations of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
This application claims benefit of U.S. Provisional Patent Application Ser. No. 62/336,073, filed May 13, 2016, and U.S. Provisional Patent Application Ser. No. 62/307,159, filed Mar. 11, 2016, which are herein incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62336073 | May 2016 | US | |
| 62307159 | Mar 2016 | US |
