Wafer carrier with active oxygen scavenging

Abstract

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

Description

WAFER CARRIER WITH ACTIVE OXYGEN SCAVENGINGCLAIM OF PRIORITY

[0001] This application claims priority from U.S. Provisional Patent Application Serial No. 63 / 448,835 bearing Attorney Docket Number 1202302-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 active oxygen 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) 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 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 semiconductor wafers from contamination due to oxygen is provided.

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

[0012] FIG. l is a graph of oxygen uptake versus time for Examples 6 to 14, according to one or more embodiments shown and described herein.

[0013] FIG. 2 is a graph of oxygen uptake versus time for Example 6 and 15 to 17, according to one or more embodiments shown and described herein.

[0014] FIG. 3 is a graph of oxygen uptake versus time for Examples 18 to 20, according to one or more embodiments shown and described herein.

[0015] FIG. 4 is a graph of oxygen uptake versus time for Examples 21 to 26, according to one or more embodiments shown and described herein.

[0016] FIG. 5 is a graph of % oxygen scavenged versus time for Examples 24 and 26 in simulated container tests, according to one or more embodiments shown and described herein.

[0017] FIG. 6 is a graph of % oxygen scavenged v. time for Examples 27 to 30 in simulated container tests, according to one or more embodiments shown and described herein.

[0018] FIGS. 7a and 7b are graphs presenting results of Simulated Container Testing for Examples 31 a and 31b, according to one or more embodiments shown and described herein.DETAILED DESCRIPTION

[0019] Reference is made hereinafter to various embodiments of wafer carriers, methods of protecting semiconductor wafers from contamination due to oxygen, and other aspects of the present invention.

[0020] 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.

[0021] 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.

[0022] Terminology

[0023] 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. The terminology used in the disclosure herein is for describing particular embodiments only and is not intended to be limiting.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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 boththe 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.

[0028] 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.

[0029] Wafer Carrier

[0030] According to an aspect of the invention, a wafer carrier comprises (a) a housing having an interior space; and (b) an oxygen scavenging compound in fluid communication with the interior space.

[0031] The wafer carrier may be for enclosing wafers such as semiconductor wafers, and, in use, contains wafers within the interior space.

[0032] The oxygen scavenging compound is suitably arranged for fluid communication with a potential source of oxygen contamination. The compound is preferably arranged within the interior space. The interior space is preferably arranged to store wafers.

[0033] Accordingly, in embodiments, the carrier may provide a microenvironment with active oxygen control for semiconductor wafers enclosed within the carrier as they move through one or more fabrication process steps.

[0034] 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.

[0035] 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.

[0036] Non-limiting examples of commercially available FOUPs include a A300 FOUP or a Spectra FOUP from Entegris.

[0037] Wafer

[0038] In embodiments, one or more semiconductor wafers are present within the interior space.

[0039] 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.

[0040] 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.

[0041] The container may contain at least 10 semiconductor wafers, for example, 10 to 50 or 10 to 25 wafers.

[0042] Housing

[0043] The wafer carrier as disclosed herein comprises a housing having an interior space.

[0044] 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.

[0045] 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, maybe 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.

[0046] 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.

[0047] 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 comprise an 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.

[0048] 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.

[0049] 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.

[0050] Oxygen Scavenging Compound

[0051] The wafer carrier as disclosed herein comprises an oxygen scavenging compound in fluid communication with the interior space.

[0052] 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.

[0053] 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.

[0054] In an embodiment Al, the oxygen scavenging compound may be an ethylenically- 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.

[0055] 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:

[0056] -[CH2-CR1=CR2-CH2-]n(I)

[0057] 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.

[0058] In embodiments, double bonds in the compound may be conjugated.

[0059] 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.

[0060] 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.

[0061] For example, the copolymer may include polycondensate segments (and, in embodiments, the copolymer predominantly comprises polycondensate segments) and OSM segments (and, in embodiments, the copolymer includes a lesser wt% of OSM segments compared to the wt% of polycondensate segments).

[0062] 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.

[0063] 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:

[0064] X-(OSM)-Y (II)

[0065] 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 II 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 polyolefinoligomers of molecular weight 100 to 10,000, polypropylene oxide oligomers, or methyl pendant aromatic compounds.

[0066] 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 and Y 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.

[0067] 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.

[0068] 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).

[0069] 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 pyromelliticdianhydride (PMDA) or maleic anhydride. The chain extender described may facilitate compatibilization of the oxygen scavenger moieties.

[0070] Oxygen Scavenging Composition

[0071] In embodiments, the oxygen scavenging compound is part of an oxygen scavenging composition.

[0072] Suitably, the oxygen scavenging composition, which includes the oxygen scavenging compound, is provided in the wafer carrier in fluid communication with the interior space.

[0073] 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.

[0074] 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.

[0075] The transition metal catalyst may be selected from cobalt stearate, cobalt oleate, cobalt linoleate, cobalt acetyl acet onate, cobalt neodecanoate, manganese stearate, manganese oleate, manganese linoleate, and manganese acetyl acetonate.

[0076] 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.

[0077] 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 than1.00 wt%, of transition metal catalyst. The aforementioned amounts suitably refer to the amount of transition metal, excluding any counter-ion or the like.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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).

[0082] 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 thermoplasticpolymer TP. In this latter case, the oxygen scavenging compound may be a copolymer as described in embodiment A2.

[0083] 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 (3d) describes a material’s dispersive forces, the ‘polarity’ parameter (6P) 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 6p=0 and 6h=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.

[0084] In embodiments, the thermoplastic polymer TP has 8P>0 and / or a 8h >0.

[0085] 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.

[0086] In embodiments, addition of certain oils to the oxygen scavenging composition may enhance the oxygen scavenging ability (e.g., rate of scavenging).

[0087] In embodiments, the oil may be selected from:

[0088] (a) olive oil;

[0089] (b) macadamia oil;

[0090] (c) avocado oil;

[0091] (d) bataua oil;

[0092] (e) gevuina oil;

[0093] (f) an oil PQ comprising:

[0094] (i) less than 25 % of linoleic acid; and / or

[0095] (ii) less than 10 % of linolenic acid; and / or

[0096] (iii) greater than 40 % of oleic acid; and / or

[0097] (iv) greater than 40 % of monounsaturated fatty acids; and / or

[0098] (v) less than 40 % of polyunsaturated fatty acids; and / or

[0099] (vi) at least 0.1 % of squalene.

[0100] A reference to “ppm” or “parts-per-million” herein (or cognate expression) refers to the parts per million of a specified material by weight.

[0101] 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).

[0102] In embodiments, the oil PQ may have the following characteristics:

[0103] - less than 25 % of linoleic acid;

[0104] - less than 10 % of linolenic acid; and

[0105] - greater than 40 % of oleic acid.

[0106] In embodiments, the oil PQ may have the following characteristics:

[0107] - 1 to 15 %, preferably 2 to 10 % of linoleic acid;

[0108] - 0.1 to 10 %, preferably 0.1 to 5 %, of linolenic acid; and

[0109] - 40 to 80 %, preferably 45 to 70 %, of oleic acid.

[0110] In embodiments, the oil PQ may have the following characteristics:

[0111] - greater than 40 % of monounsaturated fatty acids;

[0112] - less than 40 % of polyunsaturated fatty acids; and

[0113] - at least 0.1 % of squalene.

[0114] In embodiments, the oil PQ may have the following characteristics:

[0115] - 40 to 80 %, preferably 45 to 75 %, of monounsaturated fatty acids;

[0116] - 3 to 30 %, preferably 4 to 15 %, of polyunsaturated fatty acids; and

[0117] - 0.1 to 5.0 %, preferably 0.1 to 4.0 %, of squalene.

[0118] In embodiments, the oxygen scavenging composition may be in the form of a powder, compressed powder, fdm, pellets, compressed pellets or foam. It is preferably in the form of a powder, a compressed powder or a compressed pellet.

[0119] The oxygen scavenging composition (Composition I) may include:

[0120] (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

[0121] (ii) 0.009 wt% to 1.00 wt%, or 0.09 wt% to 1.00 wt%, of transition metal catalyst.

[0122] 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.

[0123] 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:

[0124] (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

[0125] (ii) 0.009 wt% to 1.00 wt%, or 0.09 wt% to 1.00 wt%, of transition metal catalyst.

[0126] 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:

[0127] (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

[0128] (ii) 0.009wt% to 1.00wt%, preferably 0.09wt% to 1.00wt%, of transition metal catalyst.

[0129] 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:

[0130] (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

[0131] (ii) 0.009 wt% to 1.00 wt%, preferably 0.09 wt% to 1.00 wt%, of transition metal catalyst.

[0132] 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.

[0133] 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 copolymerizedwith 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 copolymerized with polymer XI and / or any polyester. The balance of such an oxygen scavenging composition may include polyester and / or catalyst compound.

[0134] 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.

[0135] 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.

[0136] Receptacle

[0137] In embodiments, the oxygen scavenging compound and / or composition may be provided in a receptacle which, in turn, is arranged for fluid communication of the oxygen 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.

[0138] 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.

[0139] As an alternative to the a receptacle as described, a polymeric sheet or film comprising the oxygen scavenging compound and / or the oxygen scavenging composition may be provided and arranged within the wafer carrier.

[0140] Getter Module

[0141] In embodiments, the wafer carrier may further include a getter module comprising: a rigid polymeric housing with an access opening and the oxygen 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.

[0142] 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 fdter disposed between the cover and the oxygen scavenging compound and / or composition.

[0143] Method of Protecting Wafers

[0144] According to an aspect of the invention, a method of protecting one or more semiconductor wafers from contamination due to oxygen 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.

[0145] Use for Protecting Wafers

[0146] 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 oxygen is provided.

[0147] Novel Composition

[0148] According to an aspect of the invention, a novel oxygen scavenging composition as described in the first aspect is provided.

[0149] The oxygen scavenging composition may have any feature or combination of features as described for the oxygen scavenging composition of the first aspect.EXAMPLES

[0150] Non-limiting examples of various embodiments of the disclosed invention are provided.

[0151] Reference is made to the accompanying figures, in which:

[0152] Figure l is a graph of oxygen uptake v. time for Examples 6 to 14;

[0153] Figure 2 is a graph of oxygen uptake v. time for Example 6 and 15 to 17;

[0154] Figure 3 is a graph of oxygen uptake v. time for Examples 18 to 20;

[0155] Figure 4 is a graph of oxygen uptake v. time for Examples 21 to 26;

[0156] Figure 5 is a graph of %oxygen scavenged v. time for Examples 24 and 26 in simulated container tests;

[0157] Figure 6 is a graph of %oxygen scavenged v. time for Examples 27 to 30 in simulated container tests; and

[0158] Figures 7a and 7b are graphs presenting results of Simulated Container Testing for Examples 31a and 31b.

[0159] The following materials are referred to hereinafter.

[0160] PET refers to PET grade Laser+ C E60 (from DAK Americas).

[0161] PLA refers to PLA grade Ingeo4032D (from NatureWorks),

[0162] Elastomeric polybutadiene (E-PBD) refers to Europrene Neocis BR60 (from Versalis) a solid, elastomeric polybutadiene.

[0163] Hydroxyl terminated polybutadiene (PBD-OH) refers to Poly bd R45 HTLO (from Cray Valley), a liquid (at 25°C) hydroxyl terminated polybutadiene.

[0164] Example 1. General procedure for processing raw materials.

[0165] In the following examples, the materials were melt processed through either a twin screw extruder (TSE) or a batch mixer. For the TSE, PET and PLA samples were compounded at a barrel temperature of 250 and 200 °C, respectively. For the batch mixer, samples were processed at 100 °C and 50 rpm. The resulting material was either in the form of a pellet, produced by extrusion and pelletization (herein referred to as an “extruded pellet”) when using a TSE, or a singular solid sample, when using a batch mixer.

[0166] Example 2. Post processing heat treatment of selected compositions.

[0167] Some compositions (which may be in pellet form) described are subjected to a postprocessing heat treatment in which a composition is heated, under vacuum. A PET-containing composition may be heated to 150°C for 2.5 hours, while a PLA-containing composition may be heated to 110°C for 2 hours.

[0168] Example 3. Defining forms of compositions.

[0169] In the following examples, testing was performed on either powders, pressed pellets, or extruded pellets. Powders were prepared by cryogrinding extruded pellets to an approximate diameter of 630pm. Pressed pellets were prepared by hydraulically pressing powders with 5 tons of force for 5-10 minutes at a temperature below 25°C.

[0170] Example 4. Oxygen scavenging Analysis: Room Temperature Uptake (RTU) testing.

[0171] In the following examples, RTU was used to determine the oxygen scavenging capability of various compositions comprising polymer blends. In this test, a known mass of sample, typically 0.3g, was sealed inside a glass vial of known volume, typically 35cc, at standard conditions and sealed using a two-component epoxy (Huntsman Araldite 2000). The concentration of oxygen was then measured via an optical oxygen monitoring system [Oxysense™ Gen(III)]. The decrease in % oxygen was measured over time to determine the scavenging rate. The volume of oxygen scavenged for a given mass of material, can be calculated from % oxygen using Equation 1; where %02, measured measured %02, %02, standard atmospheric oxygen (assumed to be 21%), Vc= volume of container (typically 35cc), ms= mass of sample (typically 0.3 g).

[0172] Equation ! :

[0174] Example 5. Oxygen scavenging analysis: Simulated Container Testing (SCT).

[0175] In the following examples, Simulated Container Testing (SCT) testing was used to determine the oxygen scavenging capability of various compositions comprising polymer blends. In this test, a known mass of a sample, typically 165g, was placed in a polystyrene container which simulates a FOUP and sealed via clasps and a rubber gasket. The container was then purged withnitrogen to a known concentration of oxygen, typically 1.0%. The concentration of oxygen inside the container was then measured via an electronic oxygen meter (Smart Sensor™ oxygen detector AR8100) which was located inside the container along with the sample. SCT testing was also performed in the absence of an oxygen scavenger to determine the ingress rate of oxygen into the container.

[0176] Examples 6 to 14. Assessment of compositions including oxygen scavenger, PET and PMDA.

[0177] Hydroxyl terminated polybutadiene (PBD-OH), pyromellitic dianhydride (PMDA), and cobalt (II) stearate (Co-St) were compounded in twin screw extruder as described in Example 1 with polyethylene terephthalate (PET) at the concentrations listed in Table 1. Following compounding the resulting compositions were crystallized as described in Example 2, ground to a powder and RTU measurements were then performed as described in Example 4 on the powder samples.

[0178] Table 1.

[0179] Results are provided in Table 1 and in Figure 1. Results show improved oxygen scavenging performance was observed the higher the concentration of hydroxyl terminated polybutadiene as used in Examples 6 to 9. The best formulations were Examples 6 and 7 which had increased catalyst concentration.

[0180] Examples 6 and 7, which had increased PBD-OH and Co-St, were also tested using SCT, as described in Example 5. In the examples, 165 grams of powdered samples were tested in a container with an approximate volume of 24L. Results, provided in Table 1, show that both examples have the ability to scavenge oxygen at a rate greater than the rate of oxygen ingress for the testing chamber, which has been determined to be 4.2% per day.

[0181] Overall, the results demonstrate that a system comprised of an unconjugated polymer with a non-ferrous transition metal catalyst can provide oxygen scavenging that is sufficient to not only overcome the ingress of oxygen into the container but also scavenge additional oxygen which is initially present in the container.

[0182] Examples 15 to 17. Assessment of compositions including alternative thermoplastic polymers, scavenger, PET and PMDA.

[0183] Following the procedure for Examples 6 to 14, the PET was replaced with alternative thermoplastic polymers. Thus, compounds containing 21% PBD-OH, 2.5% Co-St, 1.8% PMDA and a balance of thermoplastic polymer (polylactic acid (PLA), polyethylene (PE) or polypropylene (PP)) were prepared in a twin screw extruder Following compounding, the resulting materials were heat treated as described in Example 2 and RTU measurements were then performed on powder samples. Results are provided in Table 2 which also includes the result for Example 6 for comparison.

[0184] Table 2.

[0185] Table 2 and figure 2 detail the Hansen solubility parameters for the thermoplastic polymers used. The parameters are a set of three parameters which numerically describe a material’s ability to dissolve in selected solvents: the ‘dispersion’ parameter (8d) 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.

[0186] The Table 2 results demonstrate the effect of the nature of the thermoplastic polymers on oxygen scavenging. If the thermoplastic polymer 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 takes place, as demonstrated by Examples 15 and 16. Alternatively, if the thermoplastic polymer is polar or contains hydrogen bonding, relatively high levels of oxygen scavenging occur, as demonstrated by Examples 6 and 17.

[0187] Examples 18 to 20. Assessment of compositions not including additional thermoplastic thermoplastic polymer.

[0188] Elastomeric polybutadiene (E-PBD) and cobalt stearate (Co-St) were compounded in a batch mixer as described in Example 1 at the concentrations listed in Table 3. Following compounding, the resulting materials were prepared as in Example 3 and RTU measurements wereperformed on powder samples as described in Example 4. Results are presented in Table 3 and Figure 3.

[0189] Table 3.

[0190] Referring to Table 3, it will be noted that there is effective scavenging even without any additional thermoplastic polymer. Inclusion of additional thermoplastic polymer may, nonetheless, be beneficial to enable the components primarily involved in oxygen scavenging to be presented in a suitable physical form.

[0191] Examples 21 to 26. Assessment of scavenging with elastomeric polybutadiene and effect of heat treatment.

[0192] Elastomeric polybutadiene (E-PBD) and cobalt stearate (Co-St) were compounded with polyethylene terephthalate (PET) in a TSE at the concentrations listed in Table 4, using the method of Example 1. In some examples hydroxyl terminated polybutadiene (PBD-OH) was used instead of E-PBD. Following compounding, the resulting compositions were heat treated as described in Example 2 and samples were prepared as described in Example 3. RTU and SCT were performed on powder samples as described in Examples 4 and 5. Results are presented in Table 4 and Figures 4 and 5 for RTU and SCT respectively.

[0193] Table 4.

[0194] The RTU results showed that the oxygen scavenging performance was improved by increasing the concentration of E-PBD and Co-St, and further improved by the addition of PBD- OH. Also, the heat treatment significantly enhanced oxygen scavenging, especially before 25 hours, as shown in Figure 4.

[0195] For the examples 24 and 26, the SCT results demonstrate the ability to scavenge oxygen at a rate greater than the rate of oxygen ingress for the testing chamber. Figure 5 shows that the examples effectively reduced the oxygen concentration in the container to nearly zero for 48 hours.

[0196] Example 27 to 30. Demonstration of the effect of physical form of oxy gen-scavenger composition on oxygen scavenging.

[0197] SCT testing was performed using material from Example 26 in order to determine the effect of physical form on oxygen scavenging. The composition of Example 26 was prepared into the forms of a powder or pressed pellets as described in example 3. The pressed pellets were tested in the compacted, as pressed form, as well as loose pellets. The results of SCT are presented in Table 5 and Figure 6.

[0198] Table 5.

[0199] The SCT results show that the pellet sample, which has the lowest surface area, exhibits the poorest oxygen scavenging activity, similar to the blank. The pressed pellets, in the compacted form, demonstrated an increased oxygen scavenging, especially after 7 hours. An additional improvement is demonstrated for pressed pellets in loose form. In this form, the material demonstrated an oxygen scavenging similar to that of the powder form and effectively reduced the oxygen concentration in the container to nearly zero for almost 24 hours.

[0200] Example 31. Comparison of ingress rates of FOUP and simulated FOUP.

[0201] The assessments described above were undertaken on a simulated FOUP of approximately the same size as a commercial FOUP, but being made from polystyrene. Most FOUPs used commercially are made from polycarbonate. A comparison was made between the simulated and commercial FOUP to confirm the validity of results. Oxygen ingress rates were assessed for each container in the absence of oxygen scavenging material. This involved purging each container to an oxygen level between 0.0- 1.0% prior to sealing. The oxygen concentration inside the containers was then measured over time. Testing was replicated multiple times for each container. For each replicate the average ingress rate was calculated using the linear slope of %02 vs. time for the first 48 hours. The averages of these values are provided in Table 6.

[0202] Table 6.

[0203] 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 isprior 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.

[0204] 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) an oxygen 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 oxygen scavenging compound is arranged for fluid communication with a potential source of oxygen 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 oxygen scavenging compound is an oxygen scavenging polymer or copolymer.

8. A carrier according to any preceding claim, wherein the oxygen scavenging compound is an ethylenically-unsaturated compound and preferably is a polymer which includes a repeat unit of formula I:-[CH2-CR1=CR2-CH2-]n (I) wherein R1and R2independently represent hydrogen atoms or optional -substituents and n is greater than 0.

9. A carrier according to any preceding claim, wherein the oxygen scavenging compound is a polybutadiene-based polymer, a famesene-based polymer or a polyisoprene-based polymer.

10. A carrier according to any preceding claim, wherein the oxygen scavenging compound is or comprises an oxygen scavenging residue of a hydroxyl -terminated polybutadiene or elastomeric polybutadiene.

11. A carrier according to any preceding claim, wherein the oxygen scavenging compound is a copolymer which includes segments of oxygen scavenging moi eties (referred to as “oxygen scavenging moiety segments” or OSM segments) derived from a polybutadiene oligomer and / or which includes a polybutadiene oligomeric chain.

12. A carrier according to any preceding claim, wherein the oxygen scavenging compound is a part of an oxygen scavenging composition wherein the oxygen scavenging composition includes the oxygen scavenging compound and a transition metal catalyst for catalyzing an oxygen scavenging reaction between the oxygen scavenging compound and oxygen which may be present in use in the wafer carrier.

13. A carrier according to claim 12, wherein the catalyst is a cobalt catalyst.

14. A carrier according to claim 12 or claim 13, wherein the oxygen scavenging composition includes at least 0.009 wt%, or at least 0.09 wt%, of transition metal catalyst; and / or less includes less than 1.50 wt%, or less than 1.00 wt%, of transition metal catalyst.

15. A carrier according to any preceding claim, wherein the oxygen scavenging composition include at least 50 wt%, or at least 75 wt%, or at least 90 wt% of thermoplastic polymers in total; and / or includes less than 99 wt%, or less than 98 wt%, of thermoplastic polymers in total.

16. A carrier according to any one of claims 12 to 15, wherein the oxygen scavenging composition includes a thermoplastic polymer TP or a residue of a thermoplastic polymer TP, wherein the thermoplastic polymer TP is polar and / or has 8P>0 and / or a 8h >0.

17. A carrier according to any one of claims 12 to 16, wherein the oxygen scavenging composition is in a form of powder, compressed powder, film, pellets, compressed pellets, or foam.

18. A carrier according to any one of claims 12 to 17, wherein the oxygen scavenging composition comprises:(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(ii) 0.009 wt% to 1 .00 wt%, or 0.09wt% to 1 .00 wt%, of transition metal catalyst.

19. A carrier according to any one of claims 12 to 18, wherein the oxygen scavenging composition comprises:(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(ii) 0.009 wt% to 1.00 wt%, or 0.09 wt% to 1.00 wt%, of transition metal catalyst.

20. A carrier according to any one of claims 12 to 19, wherein the oxygen scavenging composition comprises:(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%, or in the range 80 to 99 wt%; and(ii) 0.009 wt% to 1.00 wt%, or 0.09 wt% to 1.00 wt%, of transition metal catalyst.

21. A carrier according to any one of claims 12 to 20, wherein the oxygen scavenging composition comprises:(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%, or 80 to 99 wt%; and(ii) 0.009 wt% to 1.00 wt%, or 0.09 wt% to 1.00 wt%, of transition metal catalyst.

22. A carrier according to any one of claims 12 to 21, wherein the oxygen scavenging composition comprises 0.09 to 15.0 wt%, or 0.90 to 10.0 wt%, of a transition metal catalyst compound, for example, a cobalt compound.

23. A carrier according to any one of claims 12 to 22, wherein the oxygen scavenging composition comprises:(a) 30 to 98 wt%, or 80 to 98 wt%, of polybutadiene which is not covalently bonded to another polymer to define a copolymer;(b) 0.09 to 15.0 wt%, or 0.90 to 10.0 wt%, of a transition metal catalyst compound; and(c) 0 to 60 wt% of polyester.

24. A carrier according to any preceding claim, wherein the oxygen scavenging compound and / or composition is provided in a receptacle which is arranged for fluid communication of the oxygen 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 oxygen, 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 one of claims 1 to 25 for protecting a semiconductor wafer from contamination due to oxygen.

28. A novel oxygen scavenging composition as described in any one of claims 12 to 25.

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