DEPOSITING MATERIAL WITH ANTIMICROBIAL PROPERTIES ON PERMEABLE SUBSTRATE USING ATOMIC LAYER DEPOSITION

Abstract

Embodiments relate to depositing a layer of antimicrobial material such as silver on a permeable substrate using atomic layer deposition (ALD). A deposition device includes two injectors that inject source precursor, reactant precursor, purge gas or a combination thereof onto the permeable substrate that passes between the injectors. Part of the gas injected by an injector penetrates the permeable substrate and is discharged by the other injector. The remaining gas injected by the injector moves in parallel to the surface of the permeable substrate and is discharged via an exhaust portion formed on the same injector. While penetrating the substrate or moving in parallel to the surface, the source precursor or the reactant precursor becomes absorbed on the substrate or react with precursor already present on the substrate to deposit the antimicrobial material on the substrate.

Description

BACKGROUND

1. Field of Art

The disclosure relates to depositing silver or a silver compound on a permeable substrate such as a membrane or fabric to afford antimicrobial properties to the substrate.

2. Description of the Related Art

Permeable substrates such as membrane and fabric have various applications. The permeable substrates may be deposited with certain materials to enhance or modify various properties. Such properties include antimicrobial properties. The permeable substrates with antimicrobial properties may be used for applications that involve sanitizing materials or body parts coming into contact with the permeable substrates from microbes. Example applications of permeable substrates with antimicrobial properties include medical equipment and house cleaning products.

Silver and silver compounds are well known to have superb antimicrobial properties. To take advantage of antimicrobial properties of silver or silver compounds, permeable substrates can be coated or deposited with silver for silver compounds or various medical or health-related applications. However, silver is a precious metal and is costly. Therefore, fabric or textile coated with silver or silver compounds tends to be expensive. Moreover, the quality of silver or silver compound coated on such fabric or textile tend to be inconsistent and non-conformal, reducing the overall efficacy of the silver or silver compound coated on such permeable substrates.

SUMMARY

Embodiments relate to depositing silver or a silver compound on a permeable substrate by atomic layer deposition (ALD). Source precursor for performing ALD is injected on a portion of the permeable substrate. Reactant precursor for performing ALD is injected on the portion of the permeable substrate by a reactant injector. The reactant precursor in conjunction with the source precursor on the permeable substrate forms silver or the silver compound on the permeable substrate. Relative movement of the permeable substrate with respect to both the source injector and the reactant injector is caused to inject the source precursor and the reactant precursor on another portion of the permeable substrate.

Embodiments also relate to an antimicrobial article of manufacture that includes a permeable substrate and silver or a silver compound deposited on the permeable substrate. The silver or the silver compound is deposited on the permeable substrate by performing ALD. ALD includes injecting source precursor on a portion of the permeable substrate and injecting reactant precursor on the portion of the permeable substrate. The reactant precursor reacts or replaces the source precursor to form silver or the silver compound on the permeable substrate.

Embodiments also relate to a deposition device for depositing silver or a silver compound on a permeable substrate by ALD. The deposition device includes a source injector, a reactant injector, and a moving mechanism. The source injector injects source precursor on a portion of the permeable substrate. The reactant injector generates and injects radicals onto the portion of the permeable substrate injected with the source precursor. The reactant injector is formed with a chamber for receiving gas and includes electrodes for generating plasma in the chamber by application of voltage difference across the electrodes. The radicals in conjunction with the source precursor on the permeable substrate form silver or the silver compound on the permeable substrate by ALD. The movement mechanism causes relative movement of the permeable substrate relative to the source injector and the reactant injector to form silver or the silver compound on other portions of the permeable substrate.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a deposition device, according to one embodiment.

FIG. 2 is a cross sectional view of the deposition device of FIG. 1 taken along line A-B, according to one embodiment.

FIGS. 3A through 3C are cross sectional views of a permeable substrate at different stages of a process associated with coating silver or silver compound, according to one embodiment.

FIG. 4 is a flowchart illustrating processes of manufacturing a permeable substrate deposited with silver or a silver compound, according to one embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments are described herein with reference to the accompanying drawings. Principles disclosed herein may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. In the description, details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the features of the embodiments.

In the drawings, like reference numerals in the drawings denote like elements. The shape, size and regions, and the like, of the drawing may be exaggerated for clarity.

Embodiments relate to depositing a layer of antimicrobial material such as silver or a silver compound on a permeable substrate using atomic layer deposition (ALD). A deposition device includes one or more injectors that inject source precursor, reactant precursor, purge gas or a combination thereof onto the permeable substrate as the permeable substrate passes between the injectors. Part of the gas injected by an injector penetrates the permeable substrate and is discharged by the other injector. The remaining gas injected by the injector moves in parallel to the surface of the permeable substrate and is discharged via an exhaust portion formed on the same injector. While penetrating the substrate or moving in parallel to the surface, the source precursor or the reactant precursor becomes absorbed on the substrate or react with precursor already present on the substrate to deposit the antimicrobial material on the substrate.

Permeable substrate described herein refers to a substrate having a planar structure where at least part of gases or liquids injected on one side of the substrate can penetrate to the opposite side of the substrate. The permeable substrate includes, among others, textile, membrane and fabric, and web. The permeable structure may be made of various materials including, among other materials, paper, polyethylene, porous metal, wool, cotton and flax.

Example Deposition Device

FIG. 1 is a perspective view of a deposition device 100, according to one embodiment. The deposition device 100 may include, among other components, an upper reactor 130A and a lower reactor 130B. A permeable substrate 120 moves from the left to right (as indicated by arrow 114) and passes between the upper and lower reactors 130A, 130B, depositing the permeable substrate 120 with a layer 140 of material. The entire deposition device 100 may be enclosed in a vacuum or in a pressurized vessel.

Although the deposition device 100 is illustrated as depositing material on the substrate 120 as the substrate moves horizontally, the deposition device 100 may be oriented so that the layer 140 is deposited as the substrate 120 moves vertically or in a different direction.

The upper reactor 130A is connected to pipes 142A, 146A, 148A supplying precursor, purge gas and a combination thereof into the upper reactor 130A. Exhaust pipes 152A and 154A are also connected to the upper reactor 130A to discharge excess precursor and purge gas from the interior of the upper reactor 130A. The upper reactor 130A has its lower surface facing the substrate 120.

The lower reactor 130B is also connected to pipes 142B, 146B, 148B to receive precursor, purge gas and a combination thereof. Exhaust pipes (e.g., pipe 154B) are also connected to the lower reactor 130B to discharge excess precursor and purge gas from the interior of the lower reactor 130B. The lower reactor 130B has its upper surface facing the substrate 120.

The deposition device 100 may perform atomic layer deposition (ALD) on the substrate 120 as the substrate 120 moves from the left to the right between the lower surface of the upper reactor 130A and the upper surface of the lower reactor 130B. ALD is performed by injecting source precursor on the substrate 120 followed by injection of the reactant precursor on the substrate 120.

FIG. 2 is a cross sectional view of the deposition device 100 taken along line A-B of FIG. 1, according to one embodiment. The upper reactor 130A may include, among other components, a source injector 202 and a reactant injector 204. The source injector 202 is connected to the pipe 142A to receive the source precursor (in combination with carrier gas such as Argon) and the reactant injector 204 is connected to the pipe 148A to receive gas for generating desired reactant precursor (in combination with carrier gas such as Argon). The carrier gas may be injected via a separate pipe (e.g., pipe 146A) or via the pipes that supply the source or gas for generating the reactant precursor. The multiple reactors can be arranged in a different sequence. For example, a reactant injector 204 may be placed to the left of a source injector 202 assuming that the substrate 280 moves from the left to the right.

The body 210 of the source injector 202 is formed with a channel 242, perforations (e.g., holes or slits) 244, a reaction chamber 234, a constriction zone 260 and an exhaust portion 262. The source precursor flows into the reaction chamber 234 via the channel 242 and the perforations 244, and reacts with the permeable substrate 120. Part of the source precursor penetrates the substrate 120 and is discharged via an exhaust portion 268 formed on the lower reactor 130B. The remaining source precursor flows through the constriction zone 260 in parallel to the surface of the substrate 120 and is discharged via the exhaust portion 262. The exhaust portion is connected to the pipe 152A and discharges the excess source precursor out of the injector 202.

When the source precursor flows through the constriction zone 260, excess source precursor is removed from the surface of the substrate 120 due to the higher speed of the source precursor in the construction zone 260. In one embodiment, the height M of the constriction zone 260 is less than ⅔ the height Z or the width W of the reaction chamber 234. Such height M is desirable to remove the source precursor from the surface of the substrate 120.

The reactant injector 204 may include, among other components, a body 214 and an electrode 247 extending across the body 214. Gas supplied by the pipe 146A is injected into a plasma chamber 246 via a channel 245. By applying a voltage signal between the inner electrode 247 and an outer electrode (i.e., the body 214), plasma is generated in the plasma chamber 246. As a result, radicals are generated in the plasma chamber 246 and flow into reaction chamber 236. The radicals function as reactant precursor that interact or replace source precursor molecules on the substrate 120.

Part of the excess radicals (generated by the reactant injector 204) pass through a constriction zone 264 and are discharged via an exhaust portion 266. The exhaust portion 266 is connected to the pipe 154B. The remaining excess radicals penetrate the substrate 120, and are discharged via an exhaust portion formed in the injector 208.

The lower reactor 130B has a structure similar to the upper reactor 130A but has an upper surface facing in a direction opposite to the upper reactor 130A. The lower reactor 130B may include a source injector 206 and a reactor injector 208. The source injector 206 receives the source precursor via the pipe 142B and injects the source precursor onto the rear surface of the substrate 120. Part of the source precursor penetrates the substrate 120 and is discharged via the exhaust portion 262. The remaining source precursor flows into the exhaust portion 268 in parallel to the surface of the substrate 120 and is discharged from the source injector 206.

The structure of the reactor injector 208 is substantially the same as the reactor injector 204, and therefore, detailed description thereof is omitted herein for the sake of brevity.

The deposition device 100 may also include a mechanism 280 for moving the substrate 120. The mechanism 280 may include a motor or an actuator that pulls or pushes the substrate 120 to the right direction as illustrated in FIG. 2. As the substrate 120 is moved progressively to the right, substantially entire surface of the substrate 120 is exposed to the source precursor and the reactant precursor, depositing material on the substrate 120 as a result.

By having an opposing set of reactors, the source precursor and the reactant precursor flow perpendicular to the surface of the substrate 120 as well as in parallel to the surface of the substrate 120. Therefore, a layer of conformal material is deposited on the flat surface as well as the pores or holes in the substrate 120. Hence, the material is deposited more evenly and completely on the substrate 120.

In order to reduce the precursor material leaked outside the deposition device 100, the distance H between the substrate 120 and the upper/lower reactor 130A, 130B is maintained at a low value. In one embodiment, the distance H is less than 1 mm, and more preferably less than hundreds of μms.

In one embodiment, Ag(fod)(PEt₃) (fod=2,2-dimethyl-6,6,7,7,8,8,8-heptafluorooctane-3,5-dionato) or (2,2-dimethylpropionato)silver(I)triethylphosphine: Ag(DMP)(TEP) is used as the source precursor. H* radicals may be used as reactant precursor. H* radicals may be generated by injecting H₂ into the plasma chambers of the reactant injectors 204, 208 and applying voltage signal across their inner and outer electrodes. In one embodiment, direct current (DC) pulses of approximately 300 kHz are applied to the inner electrodes and the outer electrodes to generate plasma in the chambers.

Instead of or in addition to depositing silver, silver compounds such as Ag_XAl_1-X, Ag_XAl_1-XO, Ag_XSi_1-X, Ag_XSi_1-XO, Ag_XNi_1-X, Ag_XNi_1-XO, Ag_XTi_1-X, or Ag_XTi_1-XO may be deposited on the permeable substrate 120. To deposit Ag_XAl_1-X or Ag_XAl_1-XO, TMA (trimethylaluminum) may be used as the source precursor. To deposit Ag_XTi_1-X, or Ag_XTi_1-XO, TEMATi (tetraethylmethylaminotitanium) may be used as the source precursor. To deposit Ag_XSi_1-X, or Ag_XSi_1-XO, HMDSN (hexa-methyl-disilazane) may be used as the source precursor. To deposit Ag_XCu_1-X or Ag_XCu_1-XO, di-iso-propylacetamidinato-copper or Cu beta-diketonates may be used as the source precursor. To deposit Ag_XNi_1-X or Ag_XNi_1-XO, nickel-dialkylamino-alkoxide complexes [Ni(dmamp)₂, Ni(emamp)₂, and Ni(deamp)₂] or bis(cyclopentadienyl)nickel (NiCp₂) as may be used as the source precursor. These silver compounds are non-stoichiometric compounds and have antimicrobial properties.

Instead of using H* radicals, hydrogen-containing precursors such as NH₃, CH₄, B₂H₆ or reducing agents such as CO may be used as reactant precursor.

In one embodiment, one or more purge gas injectors may be placed between the reactors 202, 204 and/or the reactors 206, 208 to inject purge gas onto the substrate 120. The gas injector may have the same structure as the injectors 202, 206 except that the purge gas is injected into the gas injectors instead of source precursor. By injecting the purge gas, any excess source precursor molecules (e.g., physisorbed source precursor molecules) on the substrate 120 may be removed before exposing the substrate 120 to the reactant precursor. In this way, the layer of silver or silver compounds (e.g., silver oxide or non-stoichiometric silver compounds) may be deposited on the substrate 120 becomes more even and consistent.

The deposition device 100 of FIGS. 1 and 2 are merely illustrative. Different type of depositing devices may inject source precursor material and reactant precursor material onto a substrate to deposit silver on the substrate. For example, a deposition device may include reactors at one side of the substrate (e.g., reactors 202, 204) but not at the other side of the substrate.

Permeable Substrate Deposited with Silver or Silver Compound

FIG. 3A is a cross sectional view of the permeable substrate 120 deposited with an intermediate layer 310 and a layer 320 of silver or silver compounds, according to one embodiment. If the permeable substrate 120 includes textile or polymer fibers, silver or silver compounds deposited on the permeable substrate 120 may lack adhesion compared to aluminum, silicon, titanium or oxides containing these atoms. In order to improve the adhesion of silver or silver compounds and provide uniform deposition thickness, a stable intermediate layer 310 may be deposited on the permeable substrate 120 before depositing silver or silver compounds on the substrate 120. Silver compounds such as silver oxide or non-stoichiometric silver compounds can be deposited on the permeable substrate 120 without an intermediate layer 310.

In one embodiment, the intermediate layer includes SiO₂, Al₂O₃ or TiO₂. The layer 320 of silver or silver compounds can be deposited on the intermediate layer using, for example, the deposition device 100 described above in detail with reference to FIGS. 1 and 2.

FIG. 3B is a cross section view of the permeable substrate 120 where the silver particles or silver compound particles are coalesced into nano-sized bumps 324 having width or length ranging from few nanometers to 50 nm, according to one embodiment. By forming bumps 324, the surface area of the silver or the silver compounds can be increased for enhanced antimicrobial efficiency. The bumps 324 may be formed, for example, by heat-treating the silver layer 320 under inert environment or H₂ environment, or performing hydrogen radical annealing to decrease annealing temperature with H₂ remote-plasma. Such treatment causes the silver particles or silver compound particles to self-agglomerate and create bumps 324. The bumps 324 may have regular shapes (e.g., semispherical shape) or irregular shapes.

FIG. 3C is a cross sectional diagram of the substrate 120 deposited with a diffusion barrier 330 on the bumps 324, according to one embodiment. The bumps 324 may be deposited with the diffusion barrier 330 to prevent active substances in the environment from reacting with silver or a silver compound and degrading the antimicrobial properties of the silver or the silver compound. In one embodiment, material such as SiO₂, Al₂O₃ and TiO₂ may be used as material for the diffusion barrier. The thickness of the diffusion barrier 330 may be in the range of 5 to 10 nm.

Process for Manufacturing Permeable Substrate Deposited with Silver or Silver Compound

FIG. 4 is a flowchart illustrating the processes of manufacturing a permeable substrate deposited with silver or silver compound, according to one embodiment. The intermediate layer 310 is deposited 406 on the permeable substrate 120 by using ALD or other deposition methods. Then, a layer 320 of silver is deposited 410 on the intermediate layer 310 using ALD. For this purpose, the deposition device 100 of FIGS. 1 and 2 may be used.

The self-agglomeration of silver or the silver compound is induced 414 by subjecting the permeable substrate 120 to processes such as heat-treatment or radical annealing. As a result, bumps 324 are formed on the intermediate layer 310. The diffusion barrier layer 330 is then deposited with a diffusion barrier 330 to protect the agglomerated silver or the silver compound against external influences.

The method described above with reference to FIG. 4 is merely illustrative. One or more steps (e.g., step 406 of forming an intermediate layer, step 414 of inducing self-agglomeration, and step 418 of depositing diffusion barrier) may be omitted.

Although above embodiments were described primarily with reference to depositing silver or silver compound on a permeable substrate, other materials (e.g., nickel) with antimicrobial properties may be deposited on the permeable substrate using ALD.

Depositing silver or other materials with antimicrobial properties on permeable substrate using ALD is advantageous, among other reasons, because silver, silver compounds, or other materials can be deposited thinly on the permeable substrate in a conformal manner. The thin deposition enables the permeable substrate to retain permeability and other functions of the permeable substrate while affording antimicrobial properties to the permeable substrate.

Although the present invention has been described above with respect to several embodiments, various modifications can be made within the scope of the present invention. Accordingly, the disclosure of the present invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.

Claims

1. A method of depositing silver or a silver compound on a permeable substrate, comprising: injecting source precursor for performing atomic layer deposition (ALD) on a portion of the permeable substrate by a source injector;injecting reactant precursor for performing ALD on the portion of the permeable substrate by a reactant injector, the reactant precursor in conjunction with the source precursor on the permeable substrate forming the silver or the silver compound on the permeable substrate; andcausing relative movement of the permeable substrate relative to the source injector and the reactant injector to inject the source precursor and the reactant precursor on another portion of the permeable substrate.

2. The method of claim 1, wherein the source precursor comprises at least one of Ag(fod)(PEt3) (fod=2,2-dimethyl-6,6,7,7,8,8,8-heptafluorooctane-3,5-dionato) or (2,2-dimethylpropionato)silver(I)triethylphosphine: Ag(DMP)(TEP).

3. The method of claim 1, wherein the silver compound comprises at least one of AgXAl1-X, AgXAl1-XO, AgXSi1-X, AgXSi1-XO, AgXNi1-X, AgXNi1-XO, AgXTi1-X, or AgXTi1-XO.

4. The method of claim 2, wherein the reactant precursor is H* radicals.

5. The method of claim 1, further comprising depositing an intermediate layer on the permeable substrate before forming the silver or the silver compound on the permeable substrate.

6. The method of claim 5, wherein the intermediate layer comprises at least one of SiO2, Al2O3 or TiO2.

7. The method of claim 1, further comprising depositing a diffusion barrier on the formed silver or the silver compound.

8. The method of claim 6, wherein the diffusion barrier comprises at least one of SiO2, Al2O3 or TiO2.

9. The method of claim 1, further comprising forming nano-sized bumps by inducing self-agglomeration of the formed silver or the silver compound.

10. An antimicrobial article of manufacture, comprising: a permeable substrate; andsilver or a silver compound deposited on the permeable substrate by performing atomic layer deposition, the atomic layer deposition performed by injecting source precursor on a portion of the permeable substrate and injecting reactant precursor forming the silver or the silver compound in conjunction with the source precursor on the portion of the permeable substrate.

11. The antimicrobial article of claim 10, wherein the source precursor comprises at least one of Ag(fod)(PEt3) (fod=2,2-dimethyl-6,6,7,7,8,8,8-heptafluorooctane-3,5-dionato) or (2,2-dimethylpropionato)silver(I)triethylphosphine: Ag(DMP)(TEP).

12. The antimicrobial article of claim 10, wherein the silver compound comprises at least one of AgXAl1-X, AgXAl1-XO, AgXSi1-X, AgXSi1-XO, AgXNi1-X, AgXNi1-XO, AgXTi1-X, or AgXTl1-XO.

13. The antimicrobial article of claim 10, wherein the reactant precursor is H* radicals.

14. The antimicrobial article of claim 10, further comprising an intermediate layer deposited between the permeable substrate and the silver or the silver compound.

15. The antimicrobial article of claim 14, wherein the intermediate layer comprises at least one of SiO2, Al2O3 or TiO2.

16. The antimicrobial article of claim 10, further comprising a diffusion barrier deposited on the silver or the silver compound.

17. The antimicrobial article of claim 16, wherein the diffusion barrier comprises at least one of SiO2, Al2O3 or TiO2.

18. The antimicrobial article of claim 10, further comprising nano-sized bumps formed by inducing self-agglomeration of the formed silver or the silver compound.

19. A deposition device for depositing silver or a silver compound on a permeable substrate, comprising: a source injector configured to inject source precursor on a portion of the permeable substrate;a reactant injector configured to generate and inject radicals onto the portion of the permeable substrate injected with the source precursor, the reactant injector formed with a chamber for receiving gas and comprising electrodes for generating plasma in the chamber by application of voltage difference across the electrodes, the radicals in conjunction with the source precursor on the permeable substrate forming silver or a silver compound on the permeable substrate by atomic layer deposition (ALD); anda mechanism for causing relative movement of the permeable substrate relative to the source injector and the reactant injector to form silver or the silver compound on other portions of the permeable substrate.

20. The deposition device of claim 19, further comprising another injector at an opposite side of the permeable substrate to inject the source precursor or the radicals on the permeable substrate, at least part of the source precursor or the radicals injected by the source injector or the reactant injector discharged via the other injector.