AN ANTI-STICTION FLEXIBLE MOLD AND A METHOD FOR FABRICATING THE SAME

Abstract

This application relates to an anti-stiction flexible mold comprising a layer of an anti-stiction silicon dioxide deposited onto a flexible substrate. There is also provided a method for fabricating an anti-stiction flexible mold comprising the steps of a) depositing a layer of silicon dioxide on a flexible substrate; and b) interacting the layer of silicon dioxide with an anti-stiction agent to form the anti-stiction flexible mold. The resulting anti-stiction flexible mold may have superior anti-stick properties and may enable easy separation of mold and substrates after imprinting.

Claims

1.-24. (canceled)

25. An anti-stiction flexible mold comprising a layer of an anti-stiction silicon dioxide deposited onto a flexible substrate, wherein said anti-stiction silicon dioxide layer has a thickness of 9 to 15 nm.

26. The anti-stiction flexible mold according to claim 25, wherein said anti-stiction flexible mold is substantially transparent.

27. The anti-stiction flexible mold according to claim 25, wherein the flexible substrate has a patterned surface.

28. The anti-stiction flexible mold according to claim 25, wherein the flexible substrate comprises an ultraviolet curable resist or a thermal curable resist.

29. The anti-stiction flexible mold according to claim 28, wherein the flexible substrate is an acrylic or epoxy based resist.

30. The anti-stiction flexible mold according to claim 25, wherein 90% to 100% of the surface area of the flexible substrate is covered by said anti-stiction silicon dioxide layer.

31. The anti-stiction flexible mold according to claim 25, wherein said anti-stiction silicon dioxide layer comprises an anti-stiction agent that is selected from the group consisting of fluorinated alkylsilane, alkylsilane, perfluoroalkyl-phosphonic acid and alkyl-phosphonic acid.

32. The anti-stiction flexible mold according to claim 31, wherein the fluorinated alkylsilane is of the formula R.sub.1SiX.sub.rY.sub.(3-r), wherein R.sub.1 is a C.sub.1-10 alkyl substituted with fluorine; X is an alkoxy or a halo; Y is an alkoxy, a halo or hydrogen; and r is an integer selected from the range of 1 to 3 or wherein the fluorinated alkylsilane is selected from the group consisting of perfluorodecyltrichlorosilane (FDTS), trichloroperfluorooctylsilane and perfluorodecyltrialkoxysilane.

33. A method for fabricating an anti-stiction flexible mold comprising: (a) depositing a layer of silicon dioxide on a flexible substrate; and (b) interacting said layer of silicon dioxide with an anti-stiction agent to form said anti-stiction flexible mold, wherein said interacting operation (b) comprises the operation of vaporizing the anti-stiction agent.

34. The method according to claim 33, wherein the vaporized anti-stiction agent is deposited onto the layer of silicon dioxide.

35. The method according to claim 33, wherein the anti-stiction flexible mold is substantially transparent.

36. The method according to claim 33, wherein the flexible substrate in operation (a) has a patterned surface or comprises an ultraviolet curable resist or thermal curable resist.

37. The method according to claim 36, wherein the flexible substrate is an acrylic or epoxy based resist.

38. The method according to claim 33, wherein said depositing operation (a) comprises an operation of depositing the layer of silicon dioxide by chemical vapour deposition or by physical vapour deposition.

39. The method according to claim 33, wherein said depositing operation (a) comprises an operation of forming a homogenous layer of silicon dioxide on the surface of the flexible substrate.

40. The method according to claim 33, wherein the layer of silicon dioxide deposit has a thickness of 9 to 15 nm.

41. The method according to claim 33, wherein said interacting operation (b) comprises an operation of reacting the layer of silicon dioxide with the anti-stiction agent by chemical adsorption to form a self-assembled monolayer.

42. The method according to claim 33, wherein the anti-stiction agent is selected from the group consisting of fluorinated alkylsilane, alkylsilane, perfluoroalkyl-phosphonic acid and alkyl-phosphonic acid.

43. The method according to claim 42, wherein the fluorinated alkylsilane is of the formula R.sub.1SiX.sub.rY.sub.(3-r), wherein R.sub.1 is a C.sub.1-10 alkyl substituted with fluorine; X is an alkoxy or a halo; Y is an alkoxy, a halo or hydrogen; and r is an integer selected from the range of 1 to 3 or wherein the fluorinated alkylsilane is selected from the group consisting of Perfluorodecyltrichlorosilane (FDTS), trichloroperfluorooctylsilane and perfluorodecyltrialkoxysilane.

44. An anti-stiction flexible mold produced by a method for fabricating an anti-stiction flexible mold comprising: (a) depositing a layer of silicon dioxide on a flexible substrate; and (b) interacting said layer of silicon dioxide with an anti-stiction agent to form said anti-stiction flexible mold, wherein said interacting operation (b) comprises the operation of vaporizing the anti-stiction agent.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0064] The accompanying drawings illustrate a disclosed embodiment and serves to explain the principles of the disclosed embodiment. It is to be understood, however, that the drawings are designed for purposes of illustration only, and not as a definition of the limits of the invention.

[0065] FIG. 1 is a schematic diagram depicting a representative cross sectional side view of an anti-stiction flexible mold.

[0066] FIG. 2 is a schematic diagram depicting the de-molding process utilizing the anti-stiction flexible mold as disclosed herein.

[0067] FIG. 3 is a schematic diagram illustrating a general method of fabricating the anti-stiction flexible mold.

[0068] FIG. 4 is a schematic diagram illustrating a general process of imprinting a pattern on a hard substrate using the anti-stiction flexible mold.

[0069] FIG. 5 is a diagram illustrating a comparison between (a) a layer of silicon dioxide formed by chemisorption of a fluorinated alkylsilane onto the surface of a layer of a polymeric organosilicon compound that has been oxidized with O.sub.2 plasma, and (b) a layer formed by chemisorption of a fluorinated alkylsilane onto the surface of a layer of silicon dioxide that has been deposited directly onto the substrate.

DETAILED DESCRIPTION OF DRAWINGS

[0070] Referring to FIG. 1, there is shown a representative cross-sectional side view diagram of an anti-stiction flexible mold showing a fluorinated alkylsilane (102) layer that interacted with a layer of silicon dioxide (104) that is provided on a flexible substrate made up of a UV curable resist (106) and a flexible substrate (108). The fluorinated alkylsilane (102) layer is chemisorbed onto the layer of silicon dioxide (104) to form a self-assembled monolayer (SAM) (110).

[0071] Referring to FIG. 2, there is shown a schematic diagram depicting the de-molding process utilizing the anti-stiction flexible mold (206). The anti-stiction flexible mold (206) was used to imprint a pattern on a rigid substrate (210) and subsequently removed from the rigid substrate (210) in a de-molding process. In the de-molding process, the frictional force is localized at the de-molding frontier (202) when the anti-stiction flexible mold (206) is separated from the UV curable resist (208) that is sandwiched between the anti-stiction flexible mold (206) and the rigid substrate (210) during a peeling action (204).

[0072] Referring to FIG. 3, there is shown a general method of fabricating the anti-stiction flexible mold. Here, FIG. 3(a) shows a flexible substrate (306) having a patterned UV curable resist (302) with a plurality of protrusions (304) and depressions (305). The UV curable resist (302) is provided on a flexible polymeric support (303). Hence, the flexible substrate (306) is made up of the UV curable resist (302) and the flexible polymeric support (303). In FIG. 3(b), a layer of silicon dioxide (308) is deposited directly onto the flexible substrate (306). In FIG. 3(c), a layer of fluorinated alkylsilane (310) is coated onto the layer of silicon dioxide (308) to cause the fluorinated alkylsilane to interact or react with the silicon dioxide in the silicon dioxide layer (308). The resultant anti-stiction flexible mold is thus defined by reference numeral 307.

[0073] Referring to FIG. 4, like reference numerals as those in FIG. 3 are used to define like features but are depicted with a prime () symbol. FIG. 4 is a schematic diagram illustrating a general process of imprinting a pattern on a hard substrate using the anti-stiction flexible mold (307). In FIG. 4(a), the anti-stiction flexible mold (307) is compressed with a hard substrate (312) coated with a UV curable resist (314) that is conformable to the protrusions (304) and depressions (305) of the anti-stiction flexible mold (307). Hence, the protrusions on the UV curable resist (314) correspond to the depressions (305) of the anti-stiction flexible mold (307) while the depressions of the UV curable resist (314) correspond to the protrusions (304) of the anti-stiction flexible mold (307). The hard substrate (312) in contact with the anti-stiction flexible mold (307) is then subjected to ultraviolet treatment to cure the UV curable resist (314) to form the resultant pattern. In FIG. 4(b), the anti-stiction flexible mold (307) is removed from the UV curable resist (314) in a de-molding process leaving a patterned UV curable resist (314) on the hard substrate (312).

[0074] Referring to FIG. 5, FIG. 5(a) shows a self-assembled monolayer formed by chemisorption of a fluorinated alkylsilane (402) onto the surface of a PDMS layer (404) that has been oxidized with O.sub.2 plasma, while FIG. 5(b) shows a self-assembled monolayer formed by chemisorption of a fluorinated alkylsilane (402) onto the surface of a layer of silicon dioxide (406). In comparing between FIG. 5(a) and FIG. 5(b), it can be seen that in FIG. 5(b), a more homogeneous layer of the silicon dioxide is formed as compared to that in FIG. 5(a). In addition, the silicon dioxide layer in FIG. 5(b) is an inorganic silicon dioxide layer that does not have any organic groups or moieties attached to the silicon atom. This thereby allows for enhanced interaction between the oxygen atoms of the silicon dioxide layer in FIG. 5(b) and the fluorinated alkylsilane (402).

EXAMPLES

[0075] Non-limiting examples of the invention and a comparative example will be further described in greater detail by reference to specific Examples, which should not be construed as in any way limiting the scope of the invention.

Example 1

[0076] Preparation of a Flexible Substrate with an Imprinted Resist Layer

[0077] A flexible substrate with an imprinted resist layer was fabricated using an automated roll-2-roll (R2R) nanoimprinter tool. The R2R tool was loaded with a roll of polycarbonate (PC) film (thickness of about 0.17 mm) and the resist reservoir was filled with mr-UVCUR-26 resist (obtained from Micro Resist Technology of Germany). The R2R tool used an inject printer head to disperse the resist onto the PC film as it was wound by the automated roller system. The resist coated PC film was then passed between rollers. The top roller had a nickel mold attached and mold pressed the resist as the PC film passed through. As the resist was imprinted by the nickel mold, it was simultaneously cured by UV light emitted from an LED source. Once all imprinting was completed, the regions of imprinted resist on the PC film can be cut away from the rest of the film.

Deposition of an Evaporated Layer of SiO.SUB.2 .on a Flexible Substrate

[0078] The silicon dioxide layer was deposited onto the resist by radio frequency sputtering using silicon dioxide as the target, a coating temperature of room temperature (about 25 C.), a deposition rate of 0.3 A/s, a coating pressure of 110.sup.5 Torr and an oxygen gas flow rate of 20 sccm.

Deposition of FDTS

[0079] The SiO.sub.2 coated resist was placed into a desiccator containing a small volume (approx. 50 L) of 1H,1H,2H,2H-perfluorodecyltrichlorosilane (FDTS) in a glass vial. The desiccator was sealed and placed under vacuum. The desiccator was kept at reduced pressure for up to 12 hours at room temperature. During this time, the FDTS was vaporized and deposited onto the surface of the resist and chemisorbed to the SiO.sub.2 layer.

Imprinting

[0080] The above resist was then used as a mold to imprint a UV curable resist on a glass substrate of an area of 120 mm200 mm. When the resist mold was removed from the glass substrate, it was observed that the resist mold was able to be demolded from the UV curable resist easily and the entire UV curable resist (that is 100%) was imprinted by the resist mold.

Comparative Example

Preparation of PDMS Molds

[0081] PDMS molds were prepared by mixing Sylgard 184 elastomer (PDMS) with a curing agent and pouring the mixture over a hard mold (nickel or silicon) that had been pre-treated with an anti-stick coating. The PDMS coated mold was then cured in an oven at 70 C. for about 12 hours. The PDMS layer was pealed from the hard mold and placed in a chamber and exposed to ozone to oxidise the surface. The oxidised PDMS mold was then placed into a desiccator with a small volume of FDTS and held under vacuum for up to 12 hours to coat the PDMS surface with FDTS. The PDMS mold was then used to imprint a UV curable resist on glass substrate. When the PDMS mold was removed from the glass substrate, it was observed that about 60%-70% of the UV curable resist had remained on the glass substrate and was imprinted. The other 30%-40% of the UV curable resist was stuck to the PDMS mold. Hence, the PDMS mold was not able to be demolded from the UV curable mold completely.

INDUSTRIAL APPLICABILITY

[0082] The flexible mold formed by the method of the present disclosure may be applied to facilitate the imprinting of beneficial structured coatings on rigid substrates over relatively large areas (more than 100 cm.sup.2), for example, anti-reflective coating on glass panels for display screens.

[0083] It will be apparent that various other modifications and adaptations of the invention will be apparent to the person skilled in the art after reading the foregoing disclosure without departing from the spirit and scope of the invention and it is intended that all such modifications and adaptations come within the scope of the appended claims.