Wafer carrier with moisture scavenging

Abstract

A wafer carrier includes a housing having an interior space and a moisture scavenging compound in fluid communication with the interior space. The carrier provides a microenvironment with moisture control for semiconductor wafers enclosed within the carrier as they move through fabrication process steps.

Description

WAFER CARRIER WITH MOISTURE SCAVENGINGCLAIM OF PRIORITY

[0001] This application claims priority from U.S. Provisional Patent Application Serial No. 63 / 448,843 bearing Attorney Docket Number 1202303-US-F and filed on February 28, 2023, which is hereby incorporated by reference in its entirety.TECHNICAL FIELD

[0002] The present disclosure relates generally to wafer carriers, and, more particularly, to wafer carriers for enclosing semiconductor wafers within a microenvironment with moisture scavenging as they move through one or more fabrication process steps.BACKGROUND

[0003] As semiconductor fabrication technology advances, with continuous miniaturization of devices, there are more stringent requirements in the fabrication environment and, in particular, in minimizing contamination of semiconductors.

[0004] The negative effect of moisture and oxygen on semiconductor wafers is usually a function of two parameters: contaminate concentration and exposure time. Existing solutions to the problem may focus on reducing exposure time. Alternatively, if this is uneconomical or not technically possible, steps may be taken to reduce contaminate concentration levels in any environment to which wafers are exposed. Such reduction is usually achieved by purging an environment containing wafers with extremely clean dry air or a pure inert gas, such as nitrogen.

[0005] Sealed containers, such as FOUPs (front opening unified pods), FOSBs (front opening shipping boxes) or SMIF (standard mechanical interface) pods may be used as wafer containers or reticle pods. Means may be provided for flushing the interior volume of such containers which contain the wafers in use, with nitrogen, to address and / or solve the contamination problem.

[0006] However, such flushing processes are less able to meet the technical requirements as technology advances and, therefore, the problem of maintaining a suitable environment for semiconductor wafers still needs to be addressed.SUMMARY

[0007] Embodiments of the present disclosure address the above-described problems.

[0008] According to a first aspect of the invention, a wafer carrier is provided. The wafer carrier comprises (a) a housing having an interior space; and (b) a moisture scavenging compound in fluid communication with the interior space. Optionally, the wafer carrier further comprises an oxygen scavenging compound in fluid communication with the interior space.

[0009] According to a second aspect of the invention, a method of protecting a semiconductor wafer from contamination due to moisture, and, optionally also oxygen, is provided. The method comprises (i) selecting a wafer carrier as described in the first aspect; and (ii) arranging the semiconductor wafer to be protected within the interior space of the wafer carrier.

[0010] According to a third aspect of the invention, use of a wafer carrier as described according to the first aspect for protecting a semiconductor wafer from contamination due to oxygen, and, optionally also oxygen, is provided.

[0011] According to a fourth aspect of the invention, a novel moisture scavenging composition including the moisture scavenging compound as described in the first aspect is provided.DETAILED DESCRIPTION

[0012] Reference is made hereinafter to various embodiments of wafer carriers, methods of protecting semiconductor wafers from contamination due to moisture, and, optionally also oxygen, and other aspects of the present invention.

[0013] The disclosure should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the subject matter to those skilled in the art.

[0014] Any aspect of any invention described herein may be combined with any feature described in any other aspect of any invention or embodiment described herein mutatis mutandis.

[0015] Terminology

[0016] Unless otherwise expressly defined, all technical and scientific terms used herein have the same meaning as commonly understood by a person of ordinary skill in the art. Theterminology used in the disclosure herein is for describing particular embodiments only and is not intended to be limiting.

[0017] Unless otherwise expressly stated, it not intended that any method disclosed herein be construed as requiring that its steps be performed in a specific order, nor that any article set forth herein be construed as requiring specific orders or orientations to its individual components.

[0018] Unless otherwise expressly stated, it is intended that any composition or mixture disclosed herein may comprise, consist essentially of, or consist of the disclosed components.

[0019] As used herein, the singular form of a term is intended to include the plural form of the term, unless the context clearly indicates otherwise.

[0020] As used herein, numerical values are not strictly limited to the exact numerical value recited. Instead, unless otherwise expressly stated, each numerical value is intended to mean both the exact numerical value and “about” the numerical value, which encompasses a functionally equivalent range surrounding that numerical value, such that either possibility is contemplated as an embodiment disclosed herein.

[0021] As used herein, the term “formed from” (including related terms such as “forming”) refers to, with respect to an article (or component of an article) and a thermoplastic material, that the article (or component of the article) is extruded, molded, shaped, pressed, or otherwise made, in whole or in part, from the thermoplastic material under sufficient heating to enable such forming. As such, the term “formed from” (including related terms such as “forming”) means, in some embodiments, the article (or component of an article) can comprise, consist essentially of, or consist of, the material; and, in other embodiments, the article (or component of an article) consists of the material because the article (or component of an article) is, for example, made by an extrusion process or a molding process.

[0022] Wafer Carrier

[0023] According to an aspect of the invention, a wafer carrier comprises (a) a housing having an interior space; and (b) a moisture scavenging compound in fluid communication with the interior space. In embodiments, the wafer carrier further comprises an oxygen scavenging compound in fluid communication with the interior space.

[0024] The wafer carrier may be for enclosing wafers such as semiconductor wafers, and, in use, contains wafers within the interior space.

[0025] The moisture scavenging compound is suitably arranged for fluid communication with a potential source of moisture contamination. Likewise, in embodiments when the oxygen scavenging compound is provided, it is suitably arranged for fluid communication with a potential source of oxygen contamination. The compound(s) is / are preferably arranged within the interior space. The interior space is preferably arranged to store wafers.

[0026] Accordingly, in embodiments, the carrier may provide a microenvironment with moisture control, and, optionally also oxygen control, for semiconductor wafers enclosed within the carrier as they move through one or more fabrication process steps.

[0027] For example, the wafer carrier as disclosed herein may be a FOUP (a front opening unified pod) or a SMIF (standard mechanical interface) pod. A SMIF pod may be arranged, in use, to store a multiplicity of wafers horizontally. A bottom surface of a SMIF pod may include an opening door which is suitably pivotable between open and closed positions.

[0028] Wafer carriers according to the present disclosure may include any one or more features of a commercially available FOUP or SMIF pod to the extent such features do not negate or contradict any essential aspects of the present disclosure.

[0029] Non-limiting examples of commercially available FOUPs include a A300 FOUP or a Spectra FOUP from Entegris.

[0030] Wafer

[0031] In embodiments, one or more semiconductor wafers are present within the interior space.

[0032] The semiconductor wafers may have a diameter of at least 100 mm, or, in embodiments, at least 150 mm. For example, the semiconductor wafers may have diameters in the range 100 mm to 1000 mm, or, in embodiments, in the range 150 mm to 600 mm, or, in embodiments, in the range 150 mm to 500 mm.

[0033] For example, wafer diameters accommodated in a SMIF pod may be 150 mm or 200 mm; whereas a FOUP may accommodate larger diameter wafers, for example, 300 mm or 450 mm.

[0034] The container may contain at least 10 semiconductor wafers, for example, 10 to 50 or 10 to 25 wafers.

[0035] Housing

[0036] The wafer carrier as disclosed herein comprises a housing having an interior space.

[0037] The housing has an interior space adapted to contain one or more semiconductor wafers. The housing may include a pivotable door for providing access to the interior space. The door may include a door housing and a latching mechanism operably coupled with the door housing to secure the door closed. The door may be openable for access to the interior space and, in use, to a multiplicity of wafers which may be stored in the interior space. The door may define an interior side facing the interior space. The pivotable door may be a front-opening door.

[0038] The wafer carrier, for example the interior space thereof, may include support means for supporting a plurality of wafers. The wafer carrier, for example the interior space thereof, may be arranged to contain at least 10 silicon wafers. In use, when containing silicon wafers, the wafer carrier may have a weight of at least 1 kg or at least 5 kg.

[0039] The wafer carrier may have a maximum external width of at least 30 cm, or, in embodiments, at least 40 cm; and, in embodiments, less than 80 cm or less than 60 cm. The wafer carrier may have a maximum external depth of at least 20 cm, or, in embodiments, at least 30 cm; and, in embodiments, less than 60 cm or less than 45 cm. The wafer carrier may have a maximum external height of at least 20 cm, or, in embodiments, at least 30 cm; and, in embodiments, less than 60 cm or less than 45 cm. The wafer carrier may have an external volume of at least 20,000 cm3, or, in embodiments, at least 40,000 cm3; and, in embodiments, the external volume may be less than 100,000 cm3.

[0040] The wafer carrier may be made from any suitable material or combination of materials. The housing of the wafer carrier may comprise a barrier material which is, for example, a thermoplastic material. In embodiments, the wafer carrier, for example the housing, may comprisean ESD (electrostatic discharge) material. The thermoplastic may be selected from a polycarbonate, a cyclic olefin polymer (COC) and a cyclic olefin copolymer (COP). In one embodiment, the housing may comprise a carbon-filled thermoplastic polymer, for example, a polycarbonate carbon-filled material.

[0041] In embodiments, the housing of the wafer carrier may be the same as or similar to that of a A300 FOUP or a Spectra FOUP commercially available from Entegris.

[0042] In embodiments, the wafer carrier suitably includes wafer supports and / or wafer contact areas. Such supports and / or areas may comprise the same material as described for the housing or may comprise an alternative material. For example, an alternative material may be a polyaryletherketone, for example, PEEK.

[0043] Moisture Scavenging Compound

[0044] The wafer carrier as disclosed herein comprises a moisture scavenging compound in fluid communication with the interior space.

[0045] Suitable moisture scavenging compounds may include conventional or commercially available moisture scavenging compounds. One type of moisture scavenging compound may be used alone or in combination with one or more other types of moisture scavenging compound.

[0046] In embodiments, the moisture scavenging compound may be inorganic or organic; and / or it may be polymeric or non-polymeric; and / or it may comprise one or more petroleumbased polymeric materials, inorganic materials, or bio-based materials.

[0047] In an Embodiment I, the moisture scavenging compound may be arranged to generate molecular hydrogen on reaction with moisture. Thus, in this case, the moisture is scavenged by a chemical reaction involving the moisture and the moisture scavenging compound.

[0048] Further, in Embodiment I, the moisture scavenging compound may comprise a matrix in which an active material which is arranged to generate molecular hydrogen on reaction with moisture is associated, for example embedded or preferably dispersed.

[0049] Suitable polymeric matrix materials may be selected based on the solubility of moisture in the bulk polymer. Suitable polymeric matrix materials include but are not limited to polyolefins,low density polyethylene, high density polyethylene, polypropylene, styrene-ethylene-butylene (SEBS) copolymers, nylon 6, styrene, styrene-acrylate copolymers, and ethylene vinyl acetate. The matrix may be a polymeric matrix and the active material may be dispersed therein.

[0050] In embodiments, the polymeric matrix may include at least 1 wt% of active material, preferably at least 2 wt%. The polymeric matrix may include less than 70 wt% of active material. Suitably, the polymeric matrix includes 1-50 wt%, preferably 2-40 wt% of active material. The balance of material in the polymeric matrix may predominantly comprise polymeric material.

[0051] In embodiments, the active material may comprise a metal and / or a hydride. The metal may be one or more of sodium, lithium, potassium, magnesium, zinc, and aluminum. The hydride may be inorganic, for example it may comprise a metal hydride or borohydride; or it may be organic.

[0052] For example, active materials suitable for the release of molecular hydrogen as a result of contact with water include but are not limited to: sodium metal, lithium metal, potassium metal, calcium metal, sodium hydride, lithium hydride, potassium hydride, calcium hydride, magnesium hydride, sodium borohydride, and lithium borohydride.

[0053] Non-limiting examples of other active substances may include organic hydrides such as tetramethyl disiloxane and trimethyl tin hydride, as well as metals such as magnesium, zinc, or aluminum. Where the rate of reaction between the active material and water is too slow, the addition of hydrolysis catalysts and / or agents are explicitly contemplated. For example, the rate of hydrolysis of silicon hydrides may be enhanced by the use of hydroxide or fluoride ions, transition metal salts, or noble metal catalysts.

[0054] In embodiments, the active material may also be the polymeric matrix. For example, polymeric silicon hydrides such as poly(methylhydro)siloxane provide both a polymeric matrix and an active substance capable of releasing molecular hydrogen when in contact with moisture. In embodiments, the active material may be a polymer bound material such as a polymer bound borohydride.

[0055] In embodiments, the moisture scavenging compound and / or active material comprises calcium hydride.

[0056] In an Embodiment II, the moisture scavenging compound may be inorganic and may be a porous inorganic material, suitably arranged to absorb water into pores defined in the material and retain the absorbed water therein. Such a moisture scavenging compound may comprise one or more of a metal silicate (for example a molecular sieve, magnesium aluminum silicate or a zeolite), fumed silica, amorphous silica (for example a silica gel), activated alumina, activated charcoal, silicon dioxide, mesoporous silica, a clay, or a bentonite.

[0057] In an Embodiment III, the moisture scavenging compound may be inorganic and may be an oxide. It may be an oxide of a Group I or Group II metal (for example sodium oxide or calcium oxide), a mixed metal oxide (for example soda-lime), or an oxide containing phosphorous (for example phosphorous pentoxide).

[0058] In an Embodiment IV, the moisture scavenging compound may be inorganic and may be a salt. It may be a salt of a Group I or Group II metal with the counterion being a sulfate (for example sodium sulfate or calcium sulfate) or a carbonate (for example potassium or magnesium carbonate).

[0059] In an Embodiment V, the moisture scavenging compound may be inorganic and may a hydroxide. It may be a Group I or Group II hydroxide (for example potassium hydroxide or magnesium hydroxide).

[0060] In an Embodiment VI, the moisture scavenging compound may be inorganic and may a halide (for example calcium chloride or lithium bromide).

[0061] In an Embodiment VII, the moisture scavenging compound may be a polymeric material, preferably a hygroscopic material, which may comprise one or more of alcohol- or acrylate-functionalised polymers such as polyvinyl alcohol, ethylene vinyl alcohol and polyacrylates.

[0062] In an Embodiment VIII, the moisture scavenging compound may be a hygroscopic biobased material. For example, it may comprise one or more of polycaprolactone (PCL), starches (for example corn or rice starch), sugars, fibers (for example cotton fibers, water hyacinth fibers, sisal fibers, hemp fibers, and agave fibers).

[0063] In embodiments, the moisture scavenging compound may be selected from one or more of anhydrous calcium chloride, soda-lime, silicon dioxide, mesoporous silica, magnesium aluminum silicate, molecular sieves, silica gels, and clays.

[0064] In embodiments, the moisture scavenging compound may be selected from one or more of polycaprolactone (PCL), starch, cotton fibers, and water hyacinth fibers.

[0065] When the moisture scavenging compound is particulate, particle sizes of particles of the compound may be selected to optimize scavenging.

[0066] In embodiments, the compound is preferably in the form of particles. Particles of the compound may have a d50 of less than 50pm, preferably less than 25pm, more preferably less than 10pm and, especially, 5pm or less. In some embodiments, said particles may have a d50 of less than 2pm. The d50 of said particles may be greater than lOnm, for example greater than 20nm. The d50 may be measured by Laser Diffraction, for example using a Beckman Coulter LS230 Laser Diffraction Particle Size Analyzer.

[0067] In embodiments, less than 5 vol%, less than 3 vol%, or less than 1 vol% of the particles have a particle size measured by Laser Diffraction as described herein of more than 100pm or more than 5 pm. Suitably, less than 5 vol% of the particles have a particle size of more than 5 pm. Suitably, more than 5 vol%, preferably more than 25 vol%, more preferably more than 50 vol%, especially more than 75 vol% of the particles have a particle size of more than 20nm.

[0068] The particle size distribution may be expressed by “span (S)” where S is calculated by the following equation:

[0069] S = (d90-dl0) / d50

[0070] where d90 represents a particle size in which 90% of the volume is composed of particles having a smaller diameter than the stated d90; and dlO represents a particle size in which 10% of the volume is composed of particles having a diameter smaller than the stated dlO; and d50 represents a particle size in which 50% of the volume is composed of particles having a diameter larger than the stated d50 value, and 50% of the volume is composed of particles having a diameter smaller than the stated d50 value. Particle size distributions of particles in which the span (S) is from 0.01 to 10, or from 0.01 to 5, or from 0.1 to 3, for example, may be preferred.

[0071] Moisture Scavenging Composition

[0072] In embodiments, the moisture scavenging compound is part of a moisture scavenging composition.

[0073] Suitably, the moisture scavenging composition, which includes the moisture scavenging compound, is provided in the wafer carrier in fluid communication with said interior space.

[0074] The moisture scavenging composition suitably includes the moisture scavenging compound.

[0075] In embodiments, the moisture scavenging composition may comprise the moisture scavenging compound (for example particles thereof) associated with (for example dispersed in) a polymer matrix. Examples of polymer matrix include, but are not limited to, polyethylene, low density polyethylene, linear low density polyethylene, polypropylene, polyolefin copolymers, polystyrene, polystyrene copolymers, polyacrylates, polymethacrylates, polyesters, polyvinylchloride, fluoropolymers, polyamides, polyether imides, polyphenylene sulfides, polysulfones, polyacetals, polycarbonates, polyphenylene oxides, polyurethanes, thermoplastic elastomers, epoxies, alkyds, melamines, phenolics, ureas, vinyl esters, liquid crystal polymers, cellulose, thermoplastic starch, polyhydroalkanates, polylactic acid, or combinations therof.

[0076] Particles of the moisture scavenging compounds of Embodiments I to VI in particular may be associated with, for example dispersed, in the polymer matrix to form at least part of the moisture scavenging composition.

[0077] In addition to the moisture scavenging compound, an oxygen scavenging compound may also be in fluid communication with the interior space.

[0078] Oxygen Scavenging Compound

[0079] In embodiments, the wafer carrier as disclosed herein may comprise an oxygen scavenging compound in fluid communication with the interior space.

[0080] Suitable oxygen scavenging compounds may include conventional or commercially available oxygen scavenging compounds. One type of oxygen scavenging compound may be used alone or in combination with one or more other types of oxygen scavenging compound.

[0081] In embodiments, the oxygen scavenging compound includes oxygen scavenging segments. For example, the oxygen scavenging compound may be an oxidizable organic compound. For further example, the oxygen scavenging compound may be an oxygen scavenging polymer or copolymer.

[0082] In an embodiment Al, the oxygen scavenging compound may be an ethyl enically- unsaturated compound, an amide-containing compound, for example an aliphatic or at least partially aromatic polyamide and / or a polyester modified by inclusion of ether moieties, for example, as in a polyether-polyester.

[0083] When the oxygen scavenging compound is an ethylenically-unsaturated compound, the compound may include at least two double bonds. For example, it is poly (ethylenically- unsaturated). In embodiments, it is a polymer. For example, it is a polymer which includes a repeat unit of formula I:

[0084] -[CH2-CR1=CR2-CH2-]n(I)

[0085] wherein R1and R2independently represent hydrogen atoms or optional -substituents which may be optionally-substituted alkyl groups. In embodiments, n may be greater than 0, greater than 1, greater than 2, greater than 10, greater than 100, or greater than 1000.

[0086] In embodiments, double bonds in the compound may be conjugated.

[0087] In the embodiment Al, the oxygen scavenging compound may be a polybutadiene- based polymer, a farnesene -based polymer, or a polyisoprene-based polymer. Such polymers, for example, polybutadiene-based polymers, may include terminal -OH, -COOH, or -NH2moieties or may essentially not include terminal functionality. For example, polybutadiene-based polymers may include hydroxyl -terminated polybutadiene (PBD-OH) or elastomeric polybutadiene (E- PBD), the latter may essentially not include terminal functionality.

[0088] In an embodiment A2, the oxygen scavenging compound may be a copolymer. In this case, it is an oxygen scavenging copolymer which may include segments of oxygen scavenging moieties, referred to as “oxygen scavenging moiety segments” or OSM segments.

[0089] For example, the copolymer may include polycondensate segments (and, in embodiments, the copolymer predominantly comprises polycondensate segments) and OSMsegments (and, in embodiments, the copolymer includes a lesser wt% of OSM segments compared to the wt% of polycondensate segments).

[0090] The OSM segments may be present in an amount necessary to impart the degree of oxygen scavenging capacity needed for a particular application. In embodiments, the OSM segments may be comprised of polyolefin oligomer segments which have been incorporated into the oxygen scavenging copolymer. However, other oxygen scavenging moiety segments such as polypropylene oxide oligomers and methyl pendant aromatic compounds may be included in the oxygen scavenging copolymer.

[0091] The OSM segments of the oxygen scavenging copolymer may be produced by reaction of an OSM segments precursor with a polymer (referred to as “polymer XI”), for example a polyester. The OSM segments precursor may be at least singly functionally terminated with a group capable of entering into polycondensation polymerization and / or capable of reaction with previously formed moieties of polymer XI to form new covalent bonds. Alternately, the OSM segments precursor can react with polymer end groups to provide a copolymer structure. A functionally terminated OSM segments precursor may be represented by formula II:

[0092] X-(OSM)-Y (II)

[0093] Double functionality is shown in formula II as one possibility, but the OSM segments precursor may be singly functionally terminated or functionalized to a degree greater than two. Those of ordinary skill in the art will recognize that the commercial availability of functionally terminated OSM segments precursors will obviate the need to add such functionalization. The OSM segments precursors of formula n are suitably selected to be readily oxidizable at ambient temperature, such that its auto-oxidation does not result in the generation of significant volatile or extractable by-products. In embodiments, OSM segment precursors may include polyolefin oligomers of molecular weight 100 to 10,000, polypropylene oxide oligomers, or methyl pendant aromatic compounds.

[0094] In embodiments, the OSM segments precursor may include a polybutadiene moiety. A polybutadiene moiety, when incorporated as segments in a the oxygen scavenging copolymer, may advantageously provide suitable oxygen scavenging. For example, such OSM segments may be derived from unhydrogenated polybutadiene oligomer of MW 1,000 to 3,000. In formula II, X andY are typically the same and may be any species capable of entering into polycondensation and / or transesterification, with polymer XI. A non-limiting list of possible species represented by X or Y includes -OH, -COOH, -NH2, epoxides, and substituted derivatives thereof capable of entering into step-growth, condensation and / or transesterification reactions, for example with polymer XI.

[0095] In one example of embodiment A2, the oxygen scavenging copolymer may include OSM segments derived from a polyolefin oligomer and / or which includes a polyolefin oligomeric chain. In another example, the oxygen scavenging copolymer may include OSM segments derived from a polybutadiene oligomer and / or which includes a polybutadiene oligomeric chain. The aforementioned OSM segments are suitably covalently bonded to polymer XI, for example, of a polyester, such as PET segments, of the oxygen scavenging copolymer.

[0096] In embodiments, the oxygen scavenging copolymer may include at least 60 wt% or at least 75 wt% of polyester segments (e.g., polyethylene terephthalate segments) based on the weight of the oxygen scavenging copolymer. In embodiments, the oxygen scavenging copolymer may include up to 25 wt% of OSM segments, for example, polyolefin oligomer segments which may be derived from a polybutadiene polymer and / or comprise polybutadiene oligomeric chains. The oxygen scavenging copolymer suitably includes 75 to 99.5 wt%, or 75 to 85 wt%, or 77 to 82wt% of polyester segments (e.g. polyethylene terephthalate segments) and 0.5 to 25 wt%, or 15 to 25 wt%, or 18 to 23 wt%, of polyolefin oligomer segments (e.g., derived from a polybutadiene polymer and / or comprising polybutadiene oligomeric chains).

[0097] In an embodiment A2 where the oxygen scavenging compound is a copolymer as described, for example including OSM segments copolymerization into polymer XI, the compound may further include chain extender moieties, for example derived from an anhydride, for example, an anhydride which includes more than one reactive moiety, for example pyromellitic dianhydride (PMDA) or maleic anhydride. The chain extender described may facilitate compatibilization of the oxygen scavenger moieties.

[0098] Oxygen Scavenging Composition

[0099] In embodiments, the oxygen scavenging compound is part of an oxygen scavenging composition.

[0100] Suitably, the oxygen scavenging composition, which includes the oxygen scavenging compound, is provided in the wafer carrier in fluid communication with the interior space.

[0101] The oxygen scavenging composition suitably may include the oxygen scavenging compound and a catalyst, for example, a transition metal catalyst, suitable for catalyzing oxygen scavenging reaction between the oxygen scavenging compound and oxygen which may be present in use in the wafer carrier.

[0102] The catalyst may be in the form of a salt, with the transition metal selected from the first, second or third transition series of the Periodic Table. Suitable metals and their oxidation states include, but are not limited to, manganese II or III, cobalt II or III, nickel II or III, copper I or II, rhodium II, III or IV, and ruthenium. It is preferred that the catalyst does not contain iron. The oxidation state of the metal when introduced does not need necessarily to be that of the active form. The metal may be nickel, manganese, cobalt or copper; more preferably manganese or cobalt; and even more preferably cobalt. Suitable counterions for the metal include, but are not limited to, chloride, acetate, propionate, oleate, stearate, palmitate, 2-ethylhexanoate, neodecanoate or naphthenate.

[0103] The transition metal catalyst may be selected from cobalt stearate, cobalt oleate, cobalt linoleate, cobalt acetyl acetonate, cobalt neodecanoate, manganese stearate, manganese oleate, manganese linoleate, and manganese acetylacetonate.

[0104] In embodiments, the oxygen scavenging composition may include a transition metal catalyst which is a cobalt catalyst. The catalyst may include an organic counter-ion. The catalyst may be selected from cobalt stearate, cobalt oleate, cobalt linoleate and cobalt acetylacetonate.

[0105] The oxygen scavenging composition may include at least 0.009 wt%, or at least 0.09 wt%, of transition metal catalyst. The composition suitably include less than 1.50 wt%, or less than 1.00 wt%, of transition metal catalyst. The aforementioned amounts suitably refer to the amount of transition metal, excluding any counter-ion or the like.

[0106] In embodiments, the oxygen scavenging composition may include at least 0.009 wt%, or at least 0.09 wt%, of cobalt moieties. The composition suitably includes less than 1.50 wt%, or less than 1.00 wt%, of cobalt moieties.

[0107] In embodiments, the oxygen scavenging composition may include at least 0.09 wt%, or at least 0.9 wt%, of transition metal catalyst compound, for example cobalt stearate. The composition suitably includes less than 15.0 wt%, or less than 10.0 wt%, of transition metal catalyst compound, for example cobalt stearate.

[0108] In embodiments, the oxygen scavenging composition may include at least 50 wt%, or at least 75 wt%, or at least 90 wt%, of thermoplastic polymers in total. For example, the thermoplastic polymers may be the oxygen scavenging compounds of embodiments Al and A2 and any thermoplastic polymer TP herein described. The composition suitably includes less than 99 wt%, or less than 98 wt%, of thermoplastic polymers in total.

[0109] The oxygen scavenging composition may include a thermoplastic polymer TP or a residue of a thermoplastic polymer TP. The thermoplastic polymer TP may be distinct from the oxygen scavenging compound in that the thermoplastic polymer TP is not covalently bonded to the oxygen scavenging compound; or, in some embodiments, at least some oxygen scavenging polymer may be covalently bonded to the thermoplastic polymer TP for example so that a copolymer is formed between at least between some of the oxygen scavenging polymer and the thermoplastic polymer TP (in which case the copolymer may include a residue of a thermoplastic polymer TP and a residue of the oxygen scavenging polymer).

[0110] When the oxygen scavenging composition is as described in embodiment Al and includes an oxygen scavenging compound which does not include relevant terminal functionality (e.g., it does not include terminal -OH, -COOH, or -NH2 moieties described), the oxygen scavenging compound may not be covalently bonded to the thermoplastic polymer TP. However, the oxygen scavenging composition may be made using an oxygen scavenging compound which includes relevant terminal functionality (e.g., terminal -OH, -COOH, or -NH2 moieties described) in which case the oxygen scavenging polymer may be covalently bonded to the thermoplastic polymer TP. In this latter case, the oxygen scavenging compound may be a copolymer as described in embodiment A2.

[0111] In embodiments, the thermoplastic polymer TP may be polar. For example, it may have polar functionality. For example, it may include carbonyl-containing groups (e.g., esters or ketones) or hydroxyl -containing groups (e.g., alcohols). In embodiments, it is thermoplastic.Hansen solubility parameters may be used to select suitable thermoplastic polymer TP. The parameters are a set of three parameters which numerically describe a material’s ability to dissolve in selected solvents: the ‘dispersion’ parameter (8a) describes a material’s dispersive forces, the ‘polarity’ parameter (8P) describes a material’s polarity, and the ‘hydrogen-bonding’ parameter (8h) describes a material’s ability to form hydrogen bonds. The parameters provide a quantitative way to distinguish “polar / non-polar” or “hydrophilic / hydrophobic” materials. If the thermoplastic polymer TP is non-polar or lacks hydrogen bonding (defined by a Hansen solubility parameter of 8p=0 and 8h=0, respectively) a relatively low amount of oxygen scavenging may take place. Alternatively, if the thermoplastic polymer TP is polar or contains hydrogen bonding, relatively high levels of oxygen scavenging may occur.

[0112] In embodiments, the thermoplastic polymer TP has 8P>0 and / or a 8h >0.

[0113] In embodiments, the thermoplastic polymer TP may be selected from polylactic acid, polyesters, polyethylene terephthalates, polycarbonates, polyolefins functionalized with carbonyl / carboxyl group. In further embodiments, the thermoplastic polymer TP may be selected from polylactic acid and / or polyesters, for example, polyethylene terephthalate.

[0114] In embodiments, addition of certain oils to the oxygen scavenging composition may enhance the oxygen scavenging ability (e.g., rate of scavenging).

[0115] In embodiments, the oil may be selected from:

[0116] (a) olive oil;

[0117] (b) macadamia oil;

[0118] (c) avocado oil;

[0119] (d) bataua oil;

[0120] (e) gevuina oil;

[0121] (0 an oil PQ comprising:

[0122] (i) less than 25 % of linoleic acid; and / or

[0123] (ii) less than 10 % of linolenic acid; and / or

[0124] (iii) greater than 40 % of oleic acid; and / or

[0125] (iv) greater than 40 % of monounsaturated fatty acids; and / or

[0126] (v) less than 40 % of polyunsaturated fatty acids; and / or

[0127] (vi) at least 0.1 % of squalene.

[0128] A reference to “ppm” or “parts-per-million” herein (or cognate expression) refers to the parts per million of a specified material by weight.

[0129] The % of components in oils, for example in an oil may be assessed by GC-HRMS. Analysis may be as described in, for example, “Column Selection for the Analysis of Fatty Acid Methyl Esters; Authors: Frank David, Pat Sandra, Allen K Vickers. Agilent Technologies 5989- 3760EN and the citations therein. The method involves derivatization of fatty acids to methyl esters as described in W.W. Christie, “Gas Chromatography and Lipids, A Practical Guide”, (1989), The Oily Press, Ayr, Scotland (ISBN O-9514171-O-X) and then analysis of the fatty acid methyl esters (FAMEs).

[0130] In embodiments, the oil PQ may have the following characteristics:

[0131] - less than 25 % of linoleic acid;

[0132] - less than 10 % of linolenic acid; and

[0133] - greater than 40 % of oleic acid.

[0134] In embodiments, the oil PQ may have the following characteristics:

[0135] - 1 to 15 %, preferably 2 to 10 % of linoleic acid;

[0136] - 0.1 to 10 %, preferably 0.1 to 5 %, of linolenic acid; and

[0137] - 40 to 80 %, preferably 45 to 70 %, of oleic acid.

[0138] In embodiments, the oil PQ may have the following characteristics:

[0139] - greater than 40 % of monounsaturated fatty acids;

[0140] - less than 40 % of polyunsaturated fatty acids; and

[0141] - at least 0.1 % of squalene.

[0142] In embodiments, the oil PQ may have the following characteristics:

[0143] - 40 to 80 %, preferably 45 to 75 %, of monounsaturated fatty acids;

[0144] - 3 to 30 %, preferably 4 to 15 %, of polyunsaturated fatty acids; and

[0145] - 0.1 to 5.0 %, preferably 0.1 to 4.0 %, of squalene.

[0146] In embodiments, the oxygen scavenging composition may be in the form of a powder, compressed powder, film, pellets, compressed pellets or foam. It is preferably in the form of a powder, a compressed powder or a compressed pellet.

[0147] The oxygen scavenging composition (Composition I) may include:

[0148] (i) one or more thermoplastic polymers, wherein the sum of the wt% of thermoplastic polymers in the composition is in the range 50 to 99 wt%, or in the range 80 to 99 wt%; and

[0149] (ii) 0.009 wt% to 1.00 wt%, or 0.09 wt% to 1.00 wt%, of transition metal catalyst.

[0150] Unless otherwise stated, the balance of oxygen scavenging compositions may comprise other polymers or additives (eg oils as described) and / or a counter-ion for the transition metal catalyst.

[0151] The one or more thermoplastic polymers may include one or more oxygen scavenging compounds which may comprise a polymer or copolymer as described in embodiment Al or A2. An oxygen scavenging composition (Composition II) may include:

[0152] (i) one or more oxygen scavenging compounds, wherein the sum of the wt% of oxygen scavenging compounds in the composition is in the range 50 to 99 wt%, or in the range 80 to 99 wt%; and

[0153] (ii) 0.009 wt% to 1.00 wt%, or 0.09 wt% to 1.00 wt%, of transition metal catalyst.

[0154] The one or more oxygen scavenging compounds may comprise an ethylenically- unsaturated compound which may be included in a polymer or copolymer, for example as described in embodiments Al or A2. In this case, an oxygen scavenging composition (Composition III) may include:

[0155] (i) one or more oxygen scavenging compounds which include an ethylenically- unsaturated compound, wherein the sum of the wt% of ethylenically-unsaturated compounds in the composition is in the range 50 to 99 wt%, preferably in the range 80 to 99 wt%; and

[0156] (ii) 0.009 wt% to 1.00 wt%, preferably 0.09 wt% to 1.00 wt%, of transition metal catalyst.

[0157] The one or more oxygen scavenging compounds may comprise polybutadiene or a residue of a polybutadiene (herein referred to collectively as “polybutadiene-based compounds”) which may be included in a copolymer, for example as described in embodiments Al or A2. In this case, the oxygen scavenging composition (Composition IV) may include:

[0158] (i) one or more polybutadiene-based compounds, wherein the sum of the wt% of polybutadiene-based compounds in the composition is in the range 50 to 99 wt%, preferably in the range 80 to 99 wt%; and

[0159] (ii) 0.009 wt% to 1.00 wt%, preferably 0.09 wt% to 1.00 wt%, of transition metal catalyst.

[0160] Each of the aforementioned compositions I to IV may include 0.09 to 15.0 wt%, for example, 0.90 to 10.0 wt%, of a transition metal catalyst compound, for example, a cobalt compound such as cobalt stearate.

[0161] In exemplary embodiments, the oxygen scavenging composition may comprise at least some oxygen scavenging compound which is an ethylenically-unsaturated compound, for example polybutadiene, which is not covalently bonded to another polymer (such as polymer XI and / or any polyester) to define a copolymer. In this case, the oxygen scavenging composition may include at least 20 wt%, or at least 30 wt%, or at least 40 wt% of an oxygen scavenging compound which is an ethylenically-unsaturated compound, for example polybutadiene, which is not copolymerised with polymer XI and / or any polyester. In some cases, the oxygen scavenging composition may include at least 70 wt%, or at least 80 wt%, or at least 90 wt%, of an oxygen scavenging compound which is an ethylenically-unsaturated compound, for example, polybutadiene, which is not copolymerised with polymer XI and / or any polyester. The balance of such an oxygen scavenging composition may include polyester and / or catalyst compound.

[0162] In embodiments, the oxygen scavenging composition may comprise 30 to 98 wt%, 40 to 98 wt%, 50 to 98 wt%, or 80 to 98 wt%, of polybutadiene which is not covalently bonded to another polymer (such as polymer XI and / or any polyester) to define a copolymer; 0.09 to 15.0 wt%, for example, 0.90 to 10.0 wt%, of a transition metal catalyst compound as described; and 0 to 60 wt% polyester, for example PET.

[0163] Oxygen scavenging compositions as described may be capable of relatively high oxygen uptake. For example, in the test referred to in example 4 hereinafter, the oxygen uptake may be at least 1 cc per gram of the composition. The uptake may be at least 5 or at least 10 cc per gram of the composition.

[0164] Receptacle

[0165] In embodiments, the moisture scavenging compound and / or composition may be provided in a receptacle which, in turn, is arranged for fluid communication of the moisture scavenging compound with the interior space of the housing of the wafer carrier. The receptacle may be arranged within the interior space. In embodiments, the receptacle may be porous and may comprise a porous canister, envelope, or bag, for example, a mesh bag.

[0166] In embodiments, the receptacle may be releasably securable within the interior space. For example, the receptacle may be releasably securable to a door of the housing or to an alternative internal region of the housing.

[0167] As an alternative to the receptacle as described, a polymeric sheet or film comprising the moisture scavenging compound and / or composition may be provided and arranged within the wafer carrier.

[0168] In embodiments when the oxygen scavenging compound and / or composition is provided, the oxygen scavenging compound and / or composition may be provided in a receptacle as described above but which, in turn, is arranged for fluid communication of the oxygen scavenging compound with the interior space of the housing of the wafer carrier. Alternatively, a polymeric sheet or film comprising the oxygen scavenging compound and / or composition may be provided and arranged within the wafer carrier.

[0169] In embodiments, the receptacle (or sheet or film) for the moisture scavenging compound and / or composition may be a different receptacle from the receptacle (or sheet or film) for the oxygen scavenging compound and / or composition.

[0170] Getter Module

[0171] In embodiments, the wafer carrier may further include a getter module comprising: a rigid polymeric housing with an access opening and the moisture scavenging compound and / or composition disposed within the getter module housing. The getter module may be as described in WO2016145338, the content of which is incorporated by reference as regards the features which follow.

[0172] The getter module may include at least one rigid polymeric connection feature as a part of or extending from the getter module housing, the connection feature being adapted to removably secure the getter module to an or the interior side of a or the door of the housing. The getter module housing may comprise a base and at least one cover secured to the base. The getter material may be disposed between the cover and the base. The getter module may further comprise a filter disposed between the cover and the moisture scavenging compound and / or composition.

[0173] In embodiments when the oxygen scavenging compound and / or composition is provided, the oxygen scavenging compound and / or composition may be associated with a getter module as described above.

[0174] Method of Protecting Wafers

[0175] According to an aspect of the invention, a method of protecting one or more semiconductor wafers from contamination due to moisture is provided. The method comprises steps of (i) selecting a wafer carrier as described in the first aspect; and (ii) arranging wafers to be protected within the interior space of the wafer carrier.

[0176] In embodiments, the method may extend to protecting one or more semiconductor wafers from contamination due to moisture and contamination due to oxygen.

[0177] Use for Protecting Wafers

[0178] According to an aspect of the invention, use of a wafer carrier as described according to the first aspect for protecting one or more semiconductor wafers from contamination due to moisture is provided.

[0179] In embodiments, the use may extend to protecting one or more semiconductor wafers from contamination due to moisture and contamination due to oxygen.

[0180] Novel Composition

[0181] According to an aspect of the invention, a novel moisture scavenging composition as described in the first aspect is provided.

[0182] The moisture scavenging composition may have any feature or combination of features as described for the moisture scavenging composition of the first aspect.

[0183] Every document cited herein is incorporated herein by reference in its entirety unless otherwise specified. The citation of any document is not to be construed as an admission that it is prior art with respect to any invention disclosed or claimed herein. To the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

[0184] The invention is not restricted to the details of the foregoing embodiment(s). It will be apparent that modifications and variations are possible without departing from the scope of the disclosure defined in the appended claims. Although some aspects of the present disclosure are identified herein as preferred or particularly advantageous, it is contemplated that the present disclosure is not necessarily limited to these aspects. The invention extends to any novel one, or any novel combination, of the features disclosed herein (including this specification and any accompanying claims, abstract, and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS1. A wafer carrier comprising:(a) a housing having an interior space; and(b) a moisture scavenging compound in fluid communication with the interior space.

2. A carrier according to claim 1, wherein one or more semiconductor wafers are present within the interior space.

3. A carrier according to claim 1 or claim 2, wherein the moisture scavenging compound is arranged for fluid communication with a potential source of moisture contamination and is arranged within the interior space, inside a boundary defined by outer walls of the carrier.

4. A carrier according to any preceding claim, wherein the wafer carrier is a FOUP (a front opening unified pod) or a SMIF (standard mechanical interface) pod.

5. A carrier according to any preceding claim, wherein the wafer carrier is arranged to accommodate wafers having 300 mm or 450 mm diameters.

6. A carrier according to any preceding claim, wherein the housing comprises an ESD (electrostatic discharge) material.

7. A carrier according to any preceding claim, wherein the moisture scavenging compound is arranged to generate molecular hydrogen on reaction with moisture.

8. A carrier according to any preceding claim, wherein the moisture scavenging compound is part of a composition which comprises a matrix in which an active material which is arranged to generate molecular hydrogen on reaction with moisture is associated, for example embedded or preferably dispersed.

9. A carrier according to claim 8, wherein the matrix is a polymeric matrix comprising one or more of polyolefins, low density polyethylene, high density polyethylene, polypropylene, styrene- ethylene-butylene (SEBS) copolymers, nylon 6, styrene, styrene-acrylate copolymers, and ethylene vinyl acetate.

10. A carrier according to claim 8 or claim 9, wherein the active material comprises one or more of a metal and a hydride.

11. A carrier according to claim 10, wherein the metal comprises one or more of sodium, lithium, potassium, magnesium, zinc, and aluminum; and the hydride comprises one or more of a metal hydride and borohydride.

12. A carrier according to any one of claims 8 to 11, wherein the active material comprises calcium hydride.

13. A carrier according to any one of claims 1 to 6, wherein the moisture scavenging compound comprises porous inorganic material, optionally arranged to absorb water into pores defined in the material and retain the absorbed water therein.

14. A carrier according to claim 13, wherein the moisture scavenging compound comprises one or more of metal silicate, fumed silica, amorphous silica, activated alumina, activated charcoal, silicon dioxide, mesoporous silica, clay, and bentonite.

15. A carrier according to any one of claims 1 to 6, wherein the moisture scavenging compound comprises an oxide of a Group I or Group II metal or an oxide containing phosphorous.

16. A carrier according to any one of claims 1 to 6, wherein the moisture scavenging compound comprises a salt of a Group I or Group II metal with the counterion being a sulfate or a carbonate.

17. A carrier according to any one of claims 1 to 6, wherein the moisture scavenging compound comprises a Group I or Group II hydroxide.

18. A carrier accordingto any one of claims 1 to 6, wherein the moisture scavenging compound comprises a halide.

19. A carrier according to any one of claims 1 to 6, wherein the moisture scavenging compound comprises alcohol- or acrylate-functionalized polymers, for example polyvinyl alcohol, ethylene vinyl alcohol, and polyacrylates.

20. A carrier according to any one of claims 1 to 6, wherein the moisture scavenging compound comprises a hygroscopic biobased material.

21. A carrier according to any one of claims 1 to 6, wherein the moisture scavenging compound comprises one or more of anhydrous calcium chloride, soda-lime, silicon dioxide, mesoporous silica, magnesium aluminum silicate, molecular sieves, silica gels, and clays.

22. A carrier according to any one of claims 1 to 6, wherein the moisture scavenging compound comprises one or more of polycaprolactone (PCL), starch, cotton fibers, and water hyacinth fibers.

23. A carrier according to any preceding claim, wherein the moisture scavenging compound is part of a moisture scavenging composition.

24. A carrier according to any preceding claim, wherein the moisture scavenging compound and / or composition is provided in a receptacle which is arranged for fluid communication of the moisture scavenging compound with the interior space of the housing of the wafer carrier.

25. A carrier according to claim 24, wherein the receptacle is arranged within the interior space and is porous.

26. A method of protecting a semiconductor wafer from contamination due to moisture, the method comprising (i) selecting a wafer carrier as described in any preceding claim; and (ii) arranging the semiconductor wafer to be protected within the interior space of the wafer carrier.

27. Use of a wafer carrier as described in any preceding claim for a protecting semiconductor wafers from contamination due to moisture.

28. A carrier according to any one of claims 1 to 25, further comprising an oxygen scavenging compound in fluid communication with the interior space.

29. A method of protecting a semiconductor wafer from contamination due to moisture and oxygen, the method comprising (i) selecting a wafer carrier as described in claim 28; and (ii) arranging the semiconductor wafer to be protected within the interior space of the wafer carrier.

30. Use of a wafer carrier as described in any one of claims 28 to 29 for protecting a semiconductor wafer from contamination due to moisture and oxygen.

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