WO2009003149A1

WO2009003149A1 - Method and apparatus for deposition of materials

Info

Publication number: WO2009003149A1
Application number: PCT/US2008/068445
Authority: WO
Inventors: Ben Shelef; Bradley Edwards
Original assignee: Ben Shelef
Priority date: 2007-06-26
Filing date: 2008-06-26
Publication date: 2008-12-31

Abstract

In a method for facilitating the creation of product material from feedstock material, providing feedstock material to a first surface of a substrate, facilitating the permeation of the feedstock material from the first surface of the substrate to a second surface of the substrate, and maintaining thermal conditions in the vicinity of the second surface of the substrate such that feedstock material is converted to product material at the second surface of the substrate.

Description

Docket No. 80000093-0002 1

METHOD AND APPARATUS FOR DEPOSITION OF MATERIALS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001 ] The present application claims priority from U.S. Patent Application Serial No.

60/946,174 filed June 26, 2007, which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

[0002] The present application relates to the field of deposition processes and apparatus.

BACKGROUND OF THE INVENTION

[0003] A common industrial process for fabricating material is deposition, in which feed

(donor, precursor, feedstock) materials, usually gasses, are made to interact with a substrate and create product material on it. Commonly the interaction happens at an elevated temperature, and involves a chemical reaction. When a chemical reaction is involved in building the product material out of a gas phase feedstock material, the process is called Chemical Vapor Deposition (CVD). Deposition processes can happen in vacuum or in atmospheric pressure, and be based on gas or liquid.

[0004] Sometimes only a component of the feedstock materials becomes the product material. In these cases, the feedstock material is often named "donor" because it "donates" a component of itself onto the product material being built. The residue, or spent material is then exhausted and sometimes recycled and reused. To control the speed of the reaction, the feedstock material often includes an inert component (E.g. Argon or water) which dilutes its active components. Inertness is of course a function of the process temperature. When the feedstock composition has less carrier and more active components, it is called "rich".

[0005] The face of the substrate on which the product appears is called the reaction face, and the area where the growth reaction takes place is called the growth zone. To limit the build-up of product material to the growth zone, the donor material is often made to break down just in time by locating a catalyst (which hastens the break-down of the feedstock material and the build-up of the product material) near the reaction face, and keeping the process chamber at a temperature Docket No. 80000093-0002

below the natural pyro lytic temperature of the donor, thus keeping the donor material from donating its components before it reaches the catalyst.

[0006] Normally, when the product material is a solid layer, the growth must occur at its outermost face ("top growth" or "tip growth") since that is the only face that is exposed to the gas. However, when the product material allows passage of growth material through itself (as in the growth of Carbon Nanotubes, for example), it is possible to have the growth process remain adjacent to the substrate, pushing the older product material outwards and away from the substrate. This is called "bottom growth" or "root growth".

[0007] If a catalyst is present, then in root growth it has to stay attached to the surface

"under" the product material, whereas in tip growth it has to be carried up with the growing product material staying "over it". Root growth is rare, since typically the product material prevents or inhibits feedstock material from reaching the substrate.

[0008] Figure 1 depicts both tip (A) and root (B) growth process regimes. In both cases the feedstock gas (10) is made to build the product material (12a, 12b) on the substrate (11). The respective growth regions are shown in their respective locations - (13a) for tip growth, and (13b) for root growth. Similarly, newer deposited product material is labeled as (15a) and (15b), and older product material is labeled as (14a) and (14b). Note that while in Tip growth the product material is stationary, in Root growth the product material moves away from the substrate, in direction (16b).

[0009] Root growth is advantageous in that the conditions near the substrate can be controlled better than the conditions at the growing tip, and that the catalyst structure can potentially be reused after the product material is removed.

[0010] Root growth is limited however by the increasing difficulty of supplying the feedstock gas to the growth region as the produced material grows thicker, since the ambient feedstock gas has to penetrate this thicker material in order to reach the growth region.

[0011 ] A Nanotube is a molecule shaped like a tube with a specific diameter and of arbitrary length. It can be described as a planar hex-tiled sheet of atoms (such as Graphene) rolled up to form Docket No. 80000093-0002

the tube. The ends of the tubes are capped in some manner, sometimes by a structure resembling a fullerene. Nanotubes are often "functionalized" by adding atoms which are different than the main atom that forms the Nanotube. Only several atoms can form nanotubes, and the most prevalent one is Carbon. Carbon Nanotubes are an important industrial molecule, and are often fabricated by a CVD process.

SUMMARY OF THE INVENTION

[0012] The present application describes a novel method and apparatus for facilitating the growth of product material on a face of a substrate by supplying the feedstock gas from the face opposite the face where growth occurs and through the bulk of the substrate.

[0013] The method and apparatus may use the substrate to divide the reaction chamber into two sub-chambers, one containing mostly feedstock, and the other containing product material and reaction byproducts. The method and apparatus supply feedstock material to the first sub-chamber, and extract the byproducts from the second sub-chamber.

[0014] When this description refers to a chemical reaction that occurs on a surface, it includes chemical interactions that are directly influenced by the surface and its attached features. For example, if a ground silicon wafer has iron nanoparticles present on it that are 5 nm in diameter and act as catalysts for the conversion of gas into solid, then the entire reaction is considered to have occurred "on the surface", even though it involves gas molecules cracking on the catalyst, and nm- thick films and clouds forming around the catalyst during the creation of the solid.

[0015] The method and apparatus according to the present application provides the ability to supply feedstock material to the growth region near the substrate in a manner uninhibited by the amount of product material grown, thus allowing root growth to continue until limited by other factors, and produce product material with proportions that would otherwise be impossible or just too slow to achieve.

[0016] The method and apparatus described herein can be beneficial to any growth process, it is especially suitable to the growth of Carbon Nanotubes (CNTs). There is a large body of patents Docket No. 80000093-0002

on growth formulae for Carbon Nanotubes using deposition, such as for example, U.S. Patent No. 6,350,488. The method and apparatus described herein do not cover any particular recipe, however.

[0017] When growing CNTs, a common feedstock material is Ethylene gas (C₂H₄), a common carrier is Argon gas, the temperature range is between 600⁰C and 900⁰C, a common substrate is monocrystalline Silicon, and a common catalyst used is Iron, in nano-particle form.

[0018] One embodiment of the present application provides a method for facilitating the creation of product material from feedstock material, comprising: providing feedstock material to a first surface of a substrate, facilitating the permeation of the feedstock material from the first surface of the substrate to a second surface of the substrate, and maintaining thermal conditions in the vicinity of the second surface of the substrate such that feedstock material is converted to product material at the second surface of the substrate.

[0019] Another embodiment of the present application provides a method for facilitating the creation of product material from feedstock material, comprising: providing a substrate having a first surface and a second surface that allows feedstock material to permeate from the first surface to the second surface, providing a supply path for said feedstock material to the first surface of the substrate, and providing thermal conditions on the second surface that facilitate the conversion of feedstock material into product material at the second surface, such that feedstock material permeates through the substrate and becomes new product material on the second surface, forcing older product material away from the substrate, thus preventing the older product material from interfering with the access of the feedstock material to the second surface.

[0020] An additional embodiment of the present application provides that facilitation of the permeation of the feedstock material from the first surface of the substrate to the second surface of the substrate comprises maintaining a first pressure at the first surface of the substrate at a higher value than a second pressure at the second surface of the substrate.

[0021] Another embodiment of the present application provides that facilitation of the permeation of the feedstock material from the first surface of the substrate to the second surface of the substrate comprises providing one or more substrates from the group including an etched plate, a drilled plate, a microchannel plate, a porous plate, and a woven fabric. Docket No. 80000093-0002

[0022] An additional embodiment of the present application provides that facilitation of the permeation of the feedstock material from the first surface of the substrate to the second surface of the substrate comprises maintaining an inlet for the feedstock material in the vicinity of the first surface of the substrate and an outlet for byproducts in the vicinity of the second surface of the substrate, wherein the substrate is positioned within a housing and the substrate substantially divides the housing into a first portion defined by the first surface of the substrate and a second portion defined by the second surface of the substrate.

[0023] Another embodiment of the present application provides that facilitation of the permeation of the feedstock material from the first surface of the substrate to a second surface of the substrate comprises creating a pressure differential across the substrate so as to induce a flow of feedstock material from the first surface of the substrate towards the second surface of the substrate.

[0024] In any of the embodiments described above, the product material may comprise carbon, or a carbon nanotube. Additionally, in any of the embodiments described above, the feedstock material may comprise a gas, and the gas may be, for example, ethylene gas. The feedstock material also comprise a hydrocarbon.

[0025] Another embodiment of the present application provides that maintaining the thermal conditions in the vicinity of the second surface of the substrate such that feedstock material is converted to product material at the second surface of the substrate includes maintaining a temperature in the range of about 600⁰C to 900⁰C.

[0026] An embodiment of the present application provides an apparatus for facilitating the creation of product material from feedstock material, comprising: a housing, a substrate positioned within the housing, having a first surface and a second surface, wherein the substrate is permeable to a feedstock material, an inlet in the housing for supplying the feedstock material at a location between the housing and the first surface of the substrate, and a heating device, the heating device establishing thermal conditions at the second surface of the substrate suitable for deposition of product material on the second surface of the substrate.

[0027] Another embodiment of the present application provides that the feedstock material permeates through the substrate and a portion of the feedstock material becomes product material Docket No. 80000093-0002

on the second surface of the substrate, and wherein product material previously deposited on the second surface of the substrate is prevented from interfering with the access of the feedstock material to the second surface of the substrate.

[0028] One embodiment of the present application provides a substrate that is substantially planar. Another embodiment provides a substrate that is cylindrical or having another shape.

[0029] A further embodiment of the present application provides that the substrate substantially divides the housing into a first portion defined by the first surface of the substrate and a second portion defined by the second surface of the substrate, wherein the inlet is located in the first portion of the housing and further comprising an outlet, wherein the outlet is located in the second portion of the housing.

[0030] The embodiments of the present application may further comprise an outlet in the housing for creating a pressure differential across the substrate in conjunction with the inlet so as to induce a flow of feedstock material from the first surface of the substrate towards the second surface of the substrate.

[0031] Another embodiment of the present application provides that said substrate is comprised of one or more elements from the group including an etched plate, a drilled plate, a microchannel plate, a porous plate, and a woven fabric.

[0032] In any of the embodiments described above the product material may comprise carbon or a carbon nanotube. Additionally, in any of the embodiments described above, the feedstock material may comprise a hydrocarbon.

[0033] Another embodiment of the present application provides that the housing is substantially sealed and further comprising a seal between the housing and the substrate wherein the substrate substantially divides the housing into a first portion defined by the first surface of the substrate and a second portion defined by the second surface of the substrate. Docket No. 80000093-0002

[0034] Any of the embodiments described above may further comprise an outlet, wherein the inlet is located in the first portion of the housing and the outlet is located in the second portion of the housing.

[0035] Any of the prior embodiments may further comprise an enclosure having an inlet portion and an outlet portion, and the housing further including an outlet, and wherein upon insertion of the housing within the enclosure a seal is formed between the enclosure and the housing, and wherein the inlet is coupled to an inlet portion of the enclosure and the outlet is coupled to the outlet portion of the enclosure.

[0036] Any of the embodiments previously described may further comprise a seal between the housing and the substrate wherein the substrate substantially divides the housing into a first portion defined by the first surface of the substrate and a second portion defined by the second surface of the substrate, such that the produced material is formed within the second portion of the housing.

[0037] Any of the prior embodiments may further comprise a coupling between the first portion of the housing and the second portion of the housing, such that the second portion of the housing may be decoupled from the first portion of the housing and the enclosure and may act as a transport container for the product material.

[0038] An additional embodiment may further comprise a substrate including a chemical catalyst near the second surface that enhances the conversion of feedstock material into product material.

DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 shows a diagram comparing tip and root growth reactions in a furnace according to the prior art.

[0040] Figure 2 shows an apparatus for through-the-substrate root deposition according to a first embodiment of the present application. Docket No. 80000093-0002

[0041] Figure 3 shows an apparatus for diffusion based through-the-substrate root deposition according to a second embodiment of the present application.

[0042] Figure 4 shows an apparatus for sealing according to an embodiment of the present application.

[0043] Figure 5 shows a modular capsule and furnace according to an embodiment of the present application.

[0044] Figure 6 shows the substrate etching direction according to an embodiment of the present application.

DETAILED DESCRIPTION OF THE INVENTION

[0045] Figure 2 depicts a first embodiment of a growth apparatus. The main component of the growth apparatus is a permeable substrate (20) that allows passage of gas through itself, and has catalyst (21) present on one face. The growth chamber (22) is partitioned by the substrate into a feed chamber (22a) and a reaction chamber (22b). A gas inlet (23) supplies feedstock gas into the feed chamber, and a gas outlet (24) exhausts the byproducts out of the growth chamber. The direction of flow through the substrate is indicated by (27).

[0046] By arranging the gas flow in this way, a pressure difference is created across the substrate between the feed side and the reaction side, and the ability of the gas to reach the reaction zone on the substrate is primarily controlled by this pressure difference.

[0047] Another benefit of this method is that because the gas hits the reaction zone first, the older material is immersed in depleted gas (mostly by-products and carrier gas) and so problems of parasitic growth there are reduced compared to the case where active feedstock gas is present throughout the product material. The apparatus may include a feedback device that detects the composition of gas in the gas outlet. The richness of the feedstock gas and its flow rate may be adjusted up or down in response to a detection of the level of feedstock gas in the outlet, which is an indication of whether or not the reaction is consuming all of it and of the consumption level. Docket No. 80000093-0002

[0048] A radiative thermal element (25) heats the substrate through one or more transparent windows (26) in the feed chamber, and since growth happens on the opposite side of the substrate, heat delivery is also unaffected by the growth of the product material. Other commonly used heating methods may also be used, such as, for example, direct RF heating of the substrate and heated forced air or heated feedstock gas. Such heating arrangements are standard components of most deposition processes.

[0049] In addition, by heating the substrate primarily from the feed face, the product material can be kept at a lower temperature, making it more stable and further reducing any parasitic growth that may occur on it due to the presence of unconsumed feed gas down-flow of the growth region.

[0050] Since the gas is flowing in the direction of growth, the flow aids in directing the growth of the product material in the correct direction.

Chamber-to-Substrate Seal

[0051] In order to implement the through-the-substrate flow regime, the substrate has to seal against the walls of the process chamber, and the gas inlet and outlet have to be on opposite side of the substrate. Standard process chambers do not support this requirement, since they are designed to provide good flow around the substrate, not through it, and commonly handle multiple substrates laid out in a plane.

[0052] The seal between the substrate and the chamber can be either along the perimeter of the substrate (its circumference if it is round) or along its faces.

[0053] Figure 4 shows both options. A perimeter (or concentric) seal located at (40) allows the process chamber to remain a one-piece design, and use an existing door mechanism such as load lock. In some cases it is advantageous to use an adapter between the substrate and the walls of the chamber. A face seal, located at (41a) and (41b) requires that the process chamber be split in half and "pinch" the substrate, either directly or using a flexible seal. Docket No. 80000093-0002 10

[0054] While requiring a non-standard chamber, a face seal provides better sealing, since it relies on the flatness of the substrate rather than on its absolute size which will be affected by temperature. In addition, any leaks will be between one of the subchambers and the outside rater than between the two chambers, which can affect the gas monitoring process described further below.

Modular Capsule Embodiment

[0055] In the embodiment shown in Figure 5, the non-standard face-sealed reaction chamber is designed as a modular capsule independent of the rest of the apparatus ("the furnace"). The capsule creates the flow regime described in this patent, whereas the furnace supports the process by providing appropriate heat, gas flow, and gas extraction to facilitate the growth process.

[0056] Figure 5 shows a modular capsule (50) and a matching furnace (51). The furnace provides a seat (52) for the capsule, a radiative heat source (52), IR heat sensor (53), gas supply (56a) and exhaust (56b), all controlled by a central process controller (54). The furnace enclosure is vented (57) and growth can be observed from the above using a camera (58).

[0057] The capsule isolates the rest of the furnace from the growth process, eliminating cross contamination and allowing the produced material to remain encapsulated even when removed from furnace.

Diffusion-based design

[0058] Figure 3 shows a variation of through-the-substrate flow for product materials that do not permit flow of byproduct material through them. In this case the outlet (30) is placed in the feed chamber, and the flow across the substrate is based on a partial-pressure gradient - a bidirectional diffusive flow (31) of feedstock material from the feed side to the reaction side, and of byproducts in the opposite direction. Docket No. 80000093-0002 11

Permeable substrate

[0059] At the heart of the system is the permeable substrate. There are several methods to create a substrate that is suitable for growth yet allows the donor gas to flow through itself, depending on the substrate material and on the geometry of the gas passages.

[0060] A combination or layering of these embodiments can be desirable, such as when placing a thick coarse substrate under a thin smoother one for added strength.

Permeable substrate embodiment A

[0061 ] In one embodiment the substrate is etched using plasma etch or other etching process to create a pattern of holes in the micro-meter range. The etching process is controlled by a standard photo-resist based mask that restricts the etching agent from acting on any but the intended hole sites.

[0062] With etching processes, there is a widening effect associated with the penetration of the etching agent into the bulk material, and so the holes end up having conical shapes, opening away from the photo-resist side. For our application, this is actually desirable, and the cones are etched from the reaction side, yielding better gas permeability per given hole area.

[0063] Figure 6 shows a substrate with a reaction face (60a) and a feed face (60b). Arrow

(61) shows the direction of etching, opposite the eventual flow direction (62).

[0064] Etching is suitable for relatively thick (~1 mm) substrates, with numerous small

(~lum) holes. There is a high upfront cost for preparing the optical mask for the photo-resist, but the subsequent cost per substrates is low.

[0065] Hole can be etched in any pattern (e.g. square or triangular tiling) though a pseudorandom pattern that does not create straight lines of holes might be preferable in terms of mechanical strength since any line of holes make the substrate susceptible to fracture along it. Docket No. 80000093-0002

12

[0066] The total hole area does no reduce the effective growth area significantly - even a

1 :10 ratio between hole diameter and hole spacing, which is very aggressive, only reduces the effective growth area by 1%.

[0067] Etched metal sheets can be purchased, for example, from InterNet Metal Meshing of

Minneapolis, MN. (P/N BE 0201) Etched Silicon is a standard semiconductor product.

Permeable substrate embodiment B

[0068] In another embodiment, the substrate is perforated using either laser, EDM or other drilling method. Drilling methods cannot create holes as small as etching can, and the minimum hole size is at least lOum (laser) or lOOum (EDM).

[0069] Holes can be etched in any pattern (e.g. square or triangular tiling) though a pseudorandom pattern that does not create straight lines of holes might be preferable in terms of mechanical strength since any line of holes make the substrate susceptible to fracture along it. Care must be taken to not induce mechanical stresses that subsequently start fracture lines.

Permeable substrate embodiment C

[0070] In a further embodiment, the substrate is based on a drawn microchannel plate.

Drawn microchannel plates are creates by plastically elongating bundles of glass tubes, which shrink in diameter as they get longer.

[0071] MicroChannel plates are made with channels as small as lOum in diameter.

MicroChannel plates can be obtained, for example, from Hamamatsu of Bridgewater, New Jersey, USA.

Permeable substrate embodiment D

[0072] In another embodiment, the substrate is made of a porous material which is naturally permeable, so no holes are necessary. Alumina and Tungsten Carbide are two example of high temperature material that can be obtained with highly controlled porosity. Docket No. 80000093-0002 13

[0073] Open cell porous alumina ceramic substrates can be obtained, for example, from

CoorsTech of Golden, Colorado, USA.

Permeable substrate embodiment E

[0074] In this embodiment the substrate is a woven ceramic fiber cloth, ground on one face to present a flat surface, and again treated with the deposition of a continuous nano-porous alumina layer. The woven fabric is very permeable, but the deposition layer has to be thicker since the ground structure will not be as flat. Such fiber cloth material is available from Agis Inc. of Ambler, PA, or Zircar Zirconia of Florida, NY.

Permeable substrate embodiment F

[0075] In this embodiment the substrate is a thin metallic film stretched over a porous substrate that is permeable in a single direction.

Double sided chamber

[0076] Figure 7 shows an embodiment in which the reaction chamber holds two substrates

(70), with a shared reaction side, and two feed faces. There are two heating elements (71), two inlets (72), and a shared outlet (73). Growth happens simultaneously on the two substrates.

Concentric chamber

[0077] Figure 8 shows an embodiment in which the substrate (80) is cylindrical, with the inlet (82) and feed face on its inner surface, and the outlet (83) and reaction face on its outer surface. The heating element (81) is concentric as well, and located inside the chamber. The thermal window (84) is a transparent tube, allowing the heating element to radiate onto the feed face.

[0078] The two faces can also be reversed, with the feed face on the outer surface and the reaction face on the inner surface, and the heating element being a located on the outside of the process chamber. Docket No. 80000093-0002 14

Operation

[0079] Loading, in which the substrate is inserted into the chamber. In the case of the modular capsule, this happens outside the furnace and ahead of time, and the entire capsule is loaded into the furnace. During this phase, the seal between the substrate and the chamber is formed.

[0080] Initialization, in which the substrate and inner capsule walls are brought to their desired working temperature and gas supply is initiated to the feed side of the capsule. During this phase the chamber is checked for leaks, typically with an inert marker gas such as Helium.

[0081] Growth, in which product growth occurs. The process is continuously monitored and adjusted. The temperature is maintained according to the process recipe using a closed loop that compensates for heat losses through convection, conduction, and radiation. Feedstock concentrations are kept at their desired level while compensating for the conversion of feedstock material into product material. Optionally, the feedstock mixture is adjusted to yield optimal growth by increasing the feedstock flow rate until excessive amounts of feedstock are detected in the outlet. When this happens, it means that the catalyst is not consuming the feedstock properly, so either the mixture is made "leaner", the flow rate is reduced, or the catalyst is assumed to be depleted. The length and growth rate of the product are also monitored to detect anomalies.

[0082] Termination, in which the gas mixture is changed to purge gas only, and the temperature is brought down. Optionally, "poison" feedstock is added to create growth of weak product material and allow for easier separation of the product from the substrate.

[0083] Unloading, in which the substrate is removed from the chamber. In the case of the modular capsule, the entire capsule is unloaded, and the substrate can be extracted from it at a later time.

Claims

Docket No. 80000093-0002 15CLAIMSWhat is Claimed Is:

1. A method for facilitating the creation of product material from feedstock material, comprising: providing feedstock material to a first surface of a substrate; facilitating the permeation of the feedstock material from the first surface of the substrate to a second surface of the substrate; and maintaining thermal and chemical conditions in the vicinity of the second surface of the substrate such that feedstock material is converted to product material at the second surface of the substrate.

2. A method for facilitating the creation of product material from feedstock material, comprising: providing a substrate having a predetermined first surface and a predetermined second surface that allows feedstock material to permeate from the first surface to the second surface; providing a supply path for said feedstock material to the first surface of the substrate; maintaining thermal and chemical conditions on the second surface of the substrate that facilitate the conversion of feedstock material into product material in the proximity of the second surface, such that feedstock material permeates through the substrate and becomes new product material in the proximity of the second surface, forcing older product material away from the substrate, thus preventing the older product material from interfering with the access of the feedstock material to the second surface.

3. The method of claims 1-2, wherein facilitation of the permeation of the feedstock material from the first surface of the substrate to the second surface of the substrate comprises maintaining a first pressure at the first surface of the substrate at a higher value than a second pressure at the second surface of the substrate.

4. The method of claims 1-2, wherein facilitation of the permeation of the feedstock material from the first surface of the substrate to the second surface of the substrate comprises providing one Docket No. 80000093-0002 16

or more substrates from the group including an etched plate, a drilled plate, a microchannel plate, a porous plate, and a woven fabric.

5. The method of claims 1-2, wherein facilitation of the permeation of the feedstock material from the first surface of the substrate to the second surface of the substrate comprises maintaining an inlet for the feedstock material in the vicinity of the first surface of the substrate and an outlet for byproducts in the vicinity of the second surface of the substrate, wherein the substrate is positioned within a housing and the substrate substantially divides the housing into a first portion defined by the first surface of the substrate and the second portion defined by the second surface of the substrate.

6. The method of claims 1-2, wherein facilitation of the permeation of the feedstock material from the first surface of the substrate to the second surface of the substrate comprises creating a pressure differential across the substrate so as to induce a flow of feedstock material from the first surface of the substrate towards the second surface of the substrate.

7. The method of claims 1-2, wherein maintaining the chemical conditions in the vicinity of the second surface of the substrate such that feedstock material is converted to product material at the second surface of the substrate includes providing a chemical catalyst near the second surface that enhances the conversion of feedstock material into product material.

8. The method of claims 1-7, wherein the product material comprises carbon.

9. The method of claims 1-7, wherein the product material comprises a carbon nanotube.

10. The method of claims 1-7, wherein the feedstock material comprises a gas.

11. The method of claim 10, wherein the gas is ethylene gas.

12. The method of claims 1-7, wherein the feedstock material comprises a hydrocarbon.

13. The method of claims 1-7, wherein maintaining the thermal conditions in the vicinity of the second surface of the substrate such that feedstock material is converted to product material at the Docket No. 80000093-0002

17

second surface of the substrate includes maintaining a temperature in the range of about 600⁰C to 900⁰C.

14. An apparatus for facilitating the creation of product material from feedstock material, comprising: a housing; a substrate positioned within the housing, having a first surface and a second surface, wherein the substrate is permeable to a feedstock material; an inlet in the housing for supplying the feedstock material in the vicinity of the first surface of the substrate; and a heating device, the heating device establishing thermal conditions at the second surface of the substrate suitable for deposition of product material on the second surface of the substrate.

15. The apparatus of claim 14, wherein the feedstock material permeates through the substrate and a portion of the feedstock material becomes product material on the second surface of the substrate, and wherein product material previously deposited on the second surface of the substrate is prevented from interfering with the access of the feedstock material to the second surface of the substrate.

16. The apparatus of claims 14-15, wherein the substrate is substantially planar.

17. The apparatus of claims 14-15, wherein the substrate substantially divides the housing into a first portion defined by the first surface of the substrate and a second portion defined by the second surface of the substrate, wherein the inlet is located in the first portion of the housing and further comprising an outlet, wherein the outlet is located in the second portion of the housing.

18. The apparatus of claims 14-15, further comprising an outlet in the housing for creating a pressure differential across the substrate in conjunction with the inlet so as to induce a flow of feedstock material from the first surface of the substrate towards the second surface of the substrate.

19. The apparatus of claims 14-15, wherein said substrate is comprised of one or more elements from the group including an etched plate, a drilled plate, a microchannel plate, a porous plate, and a woven fabric. Docket No. 80000093-0002 18

20. The apparatus of claims 14-19, wherein the product material comprises carbon.

21. The apparatus of claims 14-19, wherein the product material comprises a carbon nanotube.

22. The apparatus of claims 14-19, wherein the feedstock material comprises a hydrocarbon.

23. The apparatus of claims 14-19, wherein the housing is substantially sealed and further comprising a seal between the housing and the substrate wherein the substrate substantially divides the housing into a first portion defined by the first surface of the substrate and a second portion defined by the second surface of the substrate.

24. The apparatus of claim 23, further comprising an outlet, wherein the inlet is located in the first portion of the housing and the outlet is located in the second portion of the housing.

25. The apparatus of claims 14-19, further comprising an enclosure having an inlet portion and an outlet portion, and the housing further including an outlet, and wherein upon insertion of the housing within the enclosure a seal is formed between the enclosure and the housing, and wherein the inlet is coupled to an inlet portion of the enclosure and the outlet is coupled to the outlet portion of the enclosure.

26. The apparatus of claim 25, further comprising a seal between the housing and the substrate wherein the substrate substantially divides the housing into a first portion defined by the first surface of the substrate and a second portion defined by the second surface of the substrate, such that the produced material is formed within the second portion of the housing.

27. The apparatus of claim 26, further comprising a coupling between the first portion of the housing and the second portion of the housing, such that the second portion of the housing may be decoupled from the first portion of the housing and the enclosure and may act as a transport container for the product material.

28. The apparatus of claim 14, wherein the substrate comprises a chemical catalyst on the second surface of the substrate that enhances the conversion of feedstock material into product material.