A storage and delivery vessel for storing GeH4 using zeolite-based adsorbents.

Abstract

A storage and dispensing system and associated method are described for selectively dispensing germane (GeH4) as a reagent gas from a vessel in which the germane is held in adsorptive relationship to a solid adsorbent medium comprising a zeolitic imidazolate framework.

Description

[Technical field]

[0001] The present invention generally relates to germane (GeH 4 The present invention relates to a storage and dispensing system and associated method for selectively dispensing germane as a reagent gas from a vessel in which a gas containing germane is held in adsorptive relationship to a solid adsorbent medium comprising a zeolitic imidazolate framework. [Background technology]

[0002] Gaseous sources (sometimes called "reagent gases") are used in a variety of industries and industrial applications. Some examples of industrial applications include those used in the processing of semiconductor materials or microelectronic devices, such as ion implantation, epitaxial growth, plasma etching, reactive ion etching, metallization, physical vapor deposition, chemical vapor deposition, atomic layer deposition, plasma deposition, photolithography, cleaning, and doping, among others, in the manufacturing processes of semiconductor, microelectronic, photovoltaic, and flat panel display devices and products.

[0003] There is a continuing need for reliable sources of high purity reagent gases in the manufacture of semiconductor materials and devices, as well as in a variety of other industrial processes and applications. Examples include silane, germane (GeH 4 ), ammonia, phosphine, arsine, diborane, stibine, hydrogen sulfide, hydrogen selenide, hydrogen telluride, and the corresponding and other halide (chlorine, bromine, iodine, fluorine) compounds. Many of these gases must be stored, transported, handled, and used with great care and many safety precautions, including storage vessels that contain the reagent gases at subatmospheric pressure.

[0004] A variety of different types of vessels are used to contain, store, transport and distribute reagent gases for industrial applications. Some vessels, referred to herein as "sorption-based vessels," contain gases using a porous adsorbent material provided within the vessel, where the reagent gas is stored by being adsorbed onto the adsorbent material. The adsorbed reagent gas may be contained within the vessel in equilibrium with the reagent gas, which may also be present in condensed or gaseous form within the vessel.

[0005] The gaseous raw material must be delivered for use in a concentrated or substantially pure form and must be available in a packaged form that provides a reliable supply of gas for efficient use in the production system.

[0006] In addition to high purity, another desirable feature of the stored gas product is a large amount of deliverable gas that can be dispensed from the storage vessel product. A large amount of deliverable material in the vessel (high "gas deliverability") increases the efficiency of using the stored gas product and its contained gaseous feedstock in the manufacturing process, since the vessel can be used for a longer period of time without replacement (compared to vessels with a smaller amount of deliverable material). Reducing the frequency of replacing used (e.g., empty) vessels with new vessels increases operational efficiency. Furthermore, reduced amounts of expensive gaseous feedstock are not used, i.e., are not utilized in the storage vessel. Summary of the Invention

[0007] German (GeH 4 ) is used in the semiconductor processing industry for a variety of purposes, for example as a germane source gas for the epitaxial growth of germanium. When used in semiconductor processing, germane must be provided at very high purity. In commercial product form, germane gas is available adsorbed on a solid adsorbent and stored in cylinders that can dispense the germane gas at a high level of purity.

[0008] The purity of germane delivered from current and past adsorption-based storage systems is sufficient for many commercial applications. Nevertheless, there remains a need for increasingly higher levels of purity of germane used in semiconductor processing. Germane can decompose during storage, including when stored in adsorption-based storage systems, to produce hydrogen gas (H 2 ), which is known to produce hydrogen peroxide. Desirable or preferred germane storage systems are those that store germane under conditions that do not cause or allow excessive decomposition of germane, e.g., systems that store germane under conditions that allow only small amounts of germane decomposition during storage. Thus, a desired feature of an adsorption-based system for storing germane is the reduction or minimization of the amount of germane decomposition that occurs during storage, and the concomitant reduction or minimization of the amount of hydrogen contained in the gaseous germane delivered from the storage system.

[0009] Examples of useful or preferred systems for storing germane in a storage vessel containing a zeolitic imidazolate framework adsorbent may exhibit useful or relatively low amounts of germane decomposition during storage of the stored germane. For example, germane stored in a storage vessel as described may exhibit less than 1% decomposition of the total amount of germane initially adsorbed, or preferably less than 0.1% decomposition, or more preferably less than 0.01% decomposition, after 365 days of storage at ambient temperature (e.g., 32°C).

[0010] Also desirably, the adsorption-based systems for storing germane can exhibit useful storage capacities with useful or advantageously high gas delivery capabilities. The described storage vessels containing zeolitic imidazolate frameworks as adsorbents for containing adsorbed germane can exhibit useful storage capacities combined with useful or advantageous delivery capabilities at sub-atmospheric pressures.

[0011] The "storage capacity" or "total storage capacity" of a storage vessel containing a sorbent and an adsorbed reagent gas, e.g., germane, refers to the amount of reagent gas that can be accommodated in the vessel per volume of the vessel. Another measure of storage capacity is the total weight (e.g., grams) of reagent gas per weight (e.g., grams) of sorbent. Storage capacity is measured as the amount of gas that can be accommodated in the vessel containing the sorbent per total volume of the vessel. Zeolitic imidazolate framework sorbents used to store reagent gases such as germane at subatmospheric pressures may inherently have lower storage capacity compared to other types of sorbents, such as carbon-type sorbents.

[0012] A different measure of the performance of a sorbent-based storage system is the "delivery capacity" of the vessel containing the reagent gas stored in the sorbent-containing vessel. "Delivery capacity" refers to the amount of stored reagent gas that can be contained in the vessel and delivered in a useful form from the vessel compared to the total amount of reagent gas contained in the vessel. Delivery capacity can be described as the amount (percentage) of stored gas that can be delivered (discharged) from the vessel compared to the total amount of stored gas stored in the vessel. Desirably, the delivery capacity of gas contained in a commercially available storage vessel can be at least 50 or 70% of the total amount of gas contained in the vessel.

[0013] According to the exemplary storage systems herein, the storage vessel containing the zeolitic imidazolate framework adsorbent and adsorbed germane can deliver at least 80, 90, 95, or 99% of the total amount of germane stored in the vessel at subatmospheric pressure, i.e., the storage vessel has a delivery capacity of at least 80, 90, 95, or 99% of the total amount of gas in the vessel. The vessel may be capable of delivering germane gas from the vessel at discharge pressures of less than 50, 30, 20, 15, 10, 5, 3, 1, or 0.5 Torr. This high level of delivery capacity of stored germane gas is useful or potentially advantageous compared to the delivery capacity of other types of adsorbent materials, such as carbon-based adsorbents, which often have a "heel" (gas that cannot be extracted at discharge pressures as low as 5 Torr) of more than 10% (mol) of the total adsorbed gas in a given system.

[0014] In one aspect, the present invention provides a zeolitic imidazolate framework adsorbent and a method for preparing GeH adsorbed on the adsorbent. 4 The present invention relates to a storage and dispensing vessel that encloses an interior volume containing GeH. The vessel includes a port, a valve attached to the port, a zeolitic imidazolate framework adsorbent within the interior volume, and GeH adsorbed on the zeolitic imidazolate framework. 4 The vessel is provided with GeH 4 To evacuate the gas, gaseous GeH is drawn from the interior volume of the vessel through a valve. 4 is selectively operable to flow [Brief description of the drawings]

[0015] [Figure 1] 1 illustrates an exemplary storage system of the present disclosure. [Diagram 2] 1 shows performance data for the storage system herein. [Diagram 3] 1 shows performance data for the storage system herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The present disclosure relates to a new and inventive system that involves storing germane in a vessel containing a zeolitic imidazolate framework adsorbent with germane adsorbed on the adsorbent, and to a new and inventive method of using the storage system to store, handle, and deliver germane.

[0017] The storage system described includes a vessel containing a zeolitic imidazolate framework (ZIF) sorbent material therein. The sorbent material is effective to contain, store and deliver germane from the storage vessel. The germane is adsorbed onto the zeolitic imidazolate framework sorbent and exists as a gas within the vessel, with a portion of the germane being adsorbed onto the zeolitic imidazolate framework and another portion being in gaseous form or condensed and gaseous form and in equilibrium with the adsorbed portion.

[0018] The pressure inside the container can be subatmospheric, meaning less than about 760 Torr (absolute). During storage of the container or during use of the container to dispense germane, the pressure inside the container can be less than 760 Torr, for example less than 700, 600, 400, 200, 100, 50, or 20 Torr.

[0019] The following explanation is based on the theory of germane (GeH 4 The present invention relates to the use of zeolitic imidazolate frameworks ("ZIFs") in adsorption-based storage vessels for storing germane. Applicants have discovered that the use of zeolitic imidazolate frameworks as adsorbents can enable useful or desirable storage capabilities for germane.

[0020] The described preferred storage systems for storage of germane adsorbed by zeolitic imidazolate framework adsorbents can exhibit useful storage capacities for germane, e.g., at least 100 g / kg, or preferably 200 g / kg, or more preferably greater than 300 g / kg.

[0021] Exemplary storage systems can also exhibit useful or advantageous delivery capabilities of germane, such as at least 80, 90, 95, or 99% delivery capabilities, meaning that the storage container can dispense at least 80, 90, 95, or 99% of the total amount of germane stored inside the container. Exemplary storage systems can dispense germane at pressures as low as 50, 20, 10, 5, 3, 1, or 0.5 Torr.

[0022] Examples of useful or preferred systems of germane stored in a storage vessel containing a zeolitic imidazolate framework adsorbent can exhibit useful or relatively small amounts of germane decomposition during storage of the stored germane. For example, germane stored in a storage vessel as described can exhibit less than 1%, or preferably less than 0.1%, or more preferably less than 0.01% decomposition based on the total initial adsorbed germane capacity over a period of 365 days at ambient temperature.

[0023] Chemical formula: GeH 4 Germane, the compound having the formula:

[0024] According to the present disclosure, germane is stored in a vessel containing a zeolitic imidazolate framework adsorbent, and germane is adsorbed onto the zeolitic imidazolate framework adsorbent. The storage system is of a type known as an adsorption-based storage system, which includes a vessel containing a zeolitic imidazolate framework adsorbent. Zeolitic imidazolate framework adsorbents are known and are known to be compositionally distinct from other known types of adsorption media, such as carbon-based adsorption media, polymeric adsorption media, and silica.

[0025] Zeolitic imidazolate frameworks are a type of metal-organic framework (MOF) known to be useful as adsorbents for storing certain reagent gases, including storage and delivery of reagent gases for use in semiconductor processing. Zeolitic imidazolate frameworks are metal-organic frameworks with tetrahedrally coordinated transition metals, such as iron (Fe), cobalt (Co), copper (Cu), or zinc (Zn), attached by imidazolate linkers, which may be the same or different within a particular ZIF composition or for single transition metal atoms of the ZIF structure. The ZIF structure comprises four-coordinated transition metals linked via imidazolate units to produce an extended framework based on a tetrahedral topology. ZIFs are said to form structural topologies equivalent to those found in zeolites and other inorganic microporous oxide materials.

[0026] Zeolitic imidazolate frameworks can be characterized by features including, among other physical and chemical properties: the specific transition metal of the framework (e.g., iron, cobalt, copper, or zinc); the chemistry of the linker (e.g., chemical substituents of the imidazolate units); the pore size of the ZIF; the surface area of ​​the ZIF; and the pore volume of the ZIF. Dozens (at least 105) of unique ZIF species or structures are known, each with a different chemical structure based on the type of transition metal and the type of linker (or linkers) that make up the framework. Each topology is identified using a unique ZIF designation, e.g., ZIF-1 through ZIF-105. For a description of ZIFs, including the specific chemical compositions and associated properties of many of the known ZIF species, see Phan et al., "Synthesis, Structure, and Carbon Dioxide Capture Properties of Zeolitic Imidazolate Frameworks," Accounts of Chemical Research, 2010, 43(1), pp. 58-67 (received April 6, 2009).

[0027] The pore size of the ZIF can affect the performance of the ZIF as an adsorbent. Exemplary ZIFs can have pore sizes ranging from about 0.2 to 13 angstroms, such as 2 to 12 angstroms or 3 to 10 angstroms. Pore size refers to the diameter of the largest sphere passing through the surface of the ZIF crystal. For use as an adsorbent in the containers herein, the ZIF can have any pore size effective to provide the desired storage performance.

[0028] Useful or preferred ZIFs can provide useful storage capacity, useful delivery capacity, and can preferably be used to store adsorbed germane in a storage vessel with a relatively low amount of decomposition of the stored germane.

[0029] One example of a ZIF that has been found to be useful in a vessel as described for adsorbing germane gas in the vessel and storing germane gas in the vessel at subatmospheric pressure is called "ZIF-8," which is zinc dimethylimidazolate (also known as "zinc 2-dimethylimidazolate"). This zeolitic imidazolate framework is reported to have a pore size of 3.4 angstroms. See U.S. Patent No. 9,138,720, which describes ZIF-8 among other MOFs.

[0030] The zeolitic imidazolate framework may be granular (particle), monolithic, or any other useful form when contained in a container for storing germane as described herein. For various exemplary embodiments, the preferred zeolitic imidazolate framework may be in the form of particles that can be easily placed (e.g., poured) into a container such as a cylinder with a relatively small opening. Additionally, other forms of zeolitic imidazolate frameworks may also be useful or preferred for different product designs, including monolithic or block adsorbents, rods, or space-filling polyhedral adsorbents.

[0031] In the exemplary container, at the temperature at which the container is used to deliver germane, the contained germane may be in a form that includes a portion that is in condensed or gaseous form (i.e., as gaseous germane) in equilibrium with the germane adsorbed on the zeolitic imidazolate framework. The temperature of the container and germane may be within the range of temperatures to which the container may be exposed during use (e.g., temperatures ranging from about 0 to about 50°C). This range includes operating temperatures, which are typical temperatures at which the container is held during controlled storage and use in a "room temperature" or room temperature environment, and is generally understood to include temperatures in the range of about 20 to about 26°C.

[0032] At the temperature at which the container is used to deliver the reagent gas, the gaseous germane may be at subatmospheric pressure, i.e., less than about 1 atmosphere (760 torr) absolute. The internal pressure of the container may be within this range during use, and may be highest when the container contains a maximum amount of germane, i.e., when the container is "full" of germane. During use, as germane is gradually removed from the container, the pressure within the container will gradually decrease, and may reach pressures of less than 700, 600, 400, 200, 100, 50, 20, 10, 5, 3, 1, or 0.5 Torr.

[0033] The container of the storage system as described may contain a zeolitic imidazolate framework adsorbent as the only type of adsorbent media present within the container, or may contain a zeolitic imidazolate framework adsorbent in combination with other types of adsorbent media, if desired. In certain currently preferred embodiments, the adsorbent media contained within the container may be substantially (e.g., at least 50, 80, 90, 95, or 97%) or entirely zeolitic imidazolate framework adsorbents as described herein, and other types of adsorbent media are not required and may be excluded from the container interior. In other words, the total amount of adsorbent contained within the container may include, consist essentially of, or consist of zeolitic imidazolate framework adsorbents, particularly including the general and specific types of zeolitic imidazolate framework adsorbents described herein.

[0034] According to this specification, a composition consisting essentially of a particular material or combination of materials is a composition that includes the particular material or materials and no more than a trace amount of any other material, e.g., no more than 2, 1, 0.5, 0.1, or 0.05 wt. % of any other material. For example, a description of a vessel interior containing an adsorbent consisting essentially of a zeolitic imidazolate framework adsorbent refers to a vessel having an interior containing a zeolitic imidazolate framework adsorbent and no more than 2, 1, 0.5, 0.1, or 0.05 wt. % of other types of adsorbent media, based on the total weight of the adsorbent media inside the vessel.

[0035] Various examples of vessel structures for storing reagent gases may be useful for storing germane using a zeolitic imidazolate framework as the adsorbent, as adapted herein. Exemplary vessels include cylindrical vessels ("cylinders") with rigid cylindrical side walls defining the vessel interior and an outlet (or "port") at the end of the cylinder. The vessel side walls may be made of metal or other rigid, e.g., reinforced, material, and are designed to withstand pressure levels that safely exceed the maximum desired pressure recommended for containing the reagent gas within the vessel interior.

[0036] FIG. 1 illustrates one example of a fluid distribution system ("fluid distribution package") as described above, in which a zeolitic imidazolate framework sorbent is disposed for storage and delivery of germane. As illustrated, the fluid distribution package 10 comprises a vessel 12 including a cylindrical wall 14 and a bed surrounding an interior volume 16 of the vessel 12, in which a zeolitic imidazolate framework sorbent 18 is disposed. The vessel 12 is joined at its upper end to a cap 20, which may have a flat feature at its periphery and circumscribe an upwardly extending boss 28 at its upper surface. The cap 20 has a central threaded opening that receives a correspondingly threaded lower portion 26 of a fluid distribution assembly.

[0037] The valve head 22 is movable between open and closed positions by any suitable operation, such as a manually operated hand wheel or a pneumatically operated actuator 30 coupled thereto. The fluid distribution system includes an outlet port 24 for dispensing gaseous germane from the fluid supply system when the valve is opened by operation of the hand wheel 30.

[0038] The zeolitic imidazolate framework sorbent 18 in the interior volume 16 of the vessel 12 may be of any suitable type as disclosed herein, including, for example, a sorbent in powder, particulate, pellet, bead, monolith, tablet, or other suitable form. The zeolitic imidazolate framework sorbent has an adsorptive affinity for germane, allowing for storage and distribution of germane within the vessel. Distribution may be performed by opening the valve head 22 to accommodate desorption of germane stored in adsorbed form on the sorbent and discharge of germane from the vessel through the fluid distribution assembly to an outlet port 24 and associated flow circuit (not shown), where pressure at the outlet port 24 causes pressure-mediated desorption and discharge of germane from the fluid supply package. For example, the distribution assembly may be coupled to a flow circuit that is at a lower pressure than the pressure within the vessel for such pressure-mediated desorption and distribution, e.g., a flow circuit that is at a subatmospheric pressure suitable for a downstream tool coupled by the flow circuit to the fluid supply package. Optionally, dispensing may include opening valve head 22 in conjunction with heating of sorbent 18 to cause thermally mediated desorption of the fluid for discharge from the fluid supply package.

[0039] The fluid supply package 10 can be loaded with germane for storage on the sorbent by first draining the fluid from the interior volume 16 of the vessel 12, followed by flowing the germane into the vessel through the outlet port 24, thereby serving the dual function of loading and dispensing fluid from the fluid supply package. Alternatively, the valve head 22 may be provided with separate fluid introduction ports for loading the vessel and loading the sorbent with the introduced fluid.

[0040] The germane in the container can be stored at any suitable pressure condition, preferably sub-atmospheric or sub-sub-atmospheric pressure, thereby enhancing the safety of the fluid supply package in conjunction with fluid supply packages such as high pressure gas cylinders. EXAMPLES

[0041] FIG. 2 is a table of the adsorption of germane on ZIF-8 (grams of germane per gram of ZIF-8) in the described storage vessel at subatmospheric pressure versus delivery pressure. The linear shape of the line for this data indicates that a high percentage of the germane contained in the vessel is deliverable. Furthermore, the linear relationship between pressure and adsorption indicates that the GeH stored in the ZIF-8-filled cylinder when plugged in for use is deliverable, as opposed to the more complex relationship for the carbon-filled cylinder. 4 This allows the amount of

[0042] FIG. 3 shows the hydrogen content of germane stored on ZIF-8 over an extended storage period.

[0043] The following table shows the amount of germane retained by the amount of ZIF-8 in the storage system as described at different pressures. The amount that can be delivered from the system and the delivery capacity of the system are also described. ZIF-8 Adsorption Storage System TIFF0007602629000001.tif56170 For this example, the relevant characteristics of the storage container, the germane, and the packaging and testing conditions are as follows: Initial hydrogen content of germane when filled into the container: less than 10 ppmV (parts per million by volume); Total volume of storage container: 0.5 liters; Amount of ZIF in storage container (mass): 140 grams; Surface area of ​​ZIF: 1500~1600m 2 / g nitrogen BET surface area; Shape and morphology of ZIF: extrudate, diameter 1-3 mm, length 1-5 cm; Storage vessel and packing adsorbent temperature: GeH in a temperature-controlled enclosure. 4 was filled at 21°C. Container and ZIF treatment before filling: ZIF-8 contains less than 10 ppm O 2 and less than 2 ppm H 2The materials were stored at all times in a glove box atmosphere at O ​​level. The storage container was loaded with ZIF-8 inside the glove box to prevent air impurities from adsorbing onto the material. The storage container with ZIF-8 was heated at 150 °C under pumping for 24 h to remove adsorbed air impurities including water. In Figure 2, GeH on ZIF-8 4 The adsorption of GeH was measured gravimetrically. The net amount of ZIF-8 was measured after loading and evacuating the test cylinder. The weight change was measured by adding a fixed amount of GeH to reach a stable target pressure. 4 When you pull out GeH and every time after that 4 Pressure was measured using a capacitance manometer (MKS model 722 "Baratron"). In Figure 3, the H 2 Details of the techniques and equipment used to measure concentrations periodically over the period of storage are provided. Storage conditions (temperature): 21°C in a temperature-controlled enclosure H in the Germanium sent out 2 Gas chromatographic technique for measuring: Gow-Mac Series 580 GC test equipment, Hayesep porous polymer column, and 50C 35 cm 3 Gas chromatograph equipped with a thermal conductivity detector, TCD, using a temperature and flow rate of 1000 s / min.

Claims

1. A zeolitic imidazolate framework adsorbent and GeH adsorbed thereon. ４ a storage and dispensing vessel enclosing an interior volume containing port, a valve attached to said port; a zeolitic imidazolate framework adsorbent within said interior volume; and The GeH adsorbed on the zeolitic imidazolate framework adsorbent ４ Including, The container is then filled with the GeH ４ and extracting gaseous GeH from the interior volume of the vessel through the valve. ４ a first inlet port and a second inlet port; A storage and dispensing vessel capable of dispensing the germane contained therein at a discharge pressure of 3 Torr or less.

2. 10. The container of claim 1 having an internal pressure of less than 760 Torr.

3. 10. The vessel of claim 1, wherein the zeolitic imidazolate framework adsorbent comprises tetrahedrally coordinated zinc atoms linked by imidazolate linkers.

4. GeH in said interior volume at subatmospheric pressure. ４ and the GeH ４ is adsorbed on the adsorbent, and the adsorbed GeH ４ Condensed or gaseous GeH in equilibrium with ４ and a portion present as a

5. 10. The container of claim 1, wherein at least 99.3% of the germane contained in the container can be dispensed from the container.

6. The container of claim 1, wherein the germane contained therein can be dispensed at a discharge pressure of 1 Torr or less.

7. G.E.H. ４ of hydrogen gas (H ２2. The container of claim 1, wherein the amount of germane decomposed to 1% of the total germane initially adsorbed is less than 1% over a period of 365 days at 30 degrees Celsius.

8. G.E.H. ４ of hydrogen gas (H ２ 2. The container of claim 1, wherein the amount of germane decomposed to 1,2-diphenyl-2,4-diphenyl-1,2-tetra ...

9. 10. The container of claim 1, wherein the adsorbent is in the form of granules, particulates, beads, or pellets.

10. The GeH from the container of claim 1 ４ The method of claim 1, further comprising the step of: ４ from inside the container to outside the container, ４ is delivered from said vessel at a pressure of 3 Torr or less.

11. The GeH ４ The method of claim 10, wherein the is delivered at a pressure of 1 Torr or less.

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