Patterning a plurality of fields on a substrate to compensate for differing evaporation times

A method of patterning a substrate comprising a plurality of fields, including, inter alia, positioning a first volume of fluid on a first subset of the plurality of fields of the substrate, with the first volume of fluid being subjected to a first evaporation time; positioning a second volume of fluid on a second subset of the plurality of fields of the substrate, differing from the first subset, with the second volume of fluid being subjected to a second evaporation time, differing from the first evaporation time; and patterning the first and second subsets of the plurality of fields, with the first subset of the plurality of fields being patterned prior to the second subset of the plurality of fields being patterned, with a volume associated with the second subset of the plurality of fields being greater than a volume associated with the first subset of the plurality of fields to compensate for the second evaporation time being greater than the first evaporation time.

BACKGROUND INFORMATION

Nano-fabrication involves the fabrication of very small structures, e.g., having features on the order of nanometers or smaller. One area in which nano-fabrication has had a sizeable impact is in the processing of integrated circuits. As the semiconductor processing industry continues to strive for larger production yields while increasing the circuits per unit area formed on a substrate, nano-fabrication becomes increasingly important. Nano-fabrication provides greater process control while allowing increased reduction of the minimum feature dimension of the structures formed. Other areas of development in which nano-fabrication has been employed include biotechnology, optical technology, mechanical systems and the like.

An exemplary nano-fabrication technique is commonly referred to as imprint lithography. Exemplary imprint lithography processes are described in detail in numerous publications, such as United States patent application publication 2004/0065976 filed as U.S. patent application Ser. No. 10/264,960, entitled “Method and a Mold to Arrange Features on a Substrate to Replicate Features having Minimal Dimensional Variability” ; United States patent application publication 2004/0065252 filed as U.S. patent application Ser. No. 10/264,926, entitled “Method of Forming a Layer on a Substrate to Facilitate Fabrication of Metrology Standards”; and U.S. Pat. No. 6,936,194, entitled “Functional Patterning Material for Imprint Lithography Processes,” all of which are assigned to the assignee of the present invention.

The imprint lithography technique disclosed in each of the aforementioned United States patent application publications and United States patent includes formation of a relief pattern in a polymerizable layer and transferring a pattern corresponding to the relief pattern into an underlying substrate. The substrate may be positioned upon a stage to obtain a desired position to facilitate patterning thereof To that end, a mold is employed spaced-apart from the substrate with a formable liquid present between the mold and the substrate. The liquid is solidified to form a patterned layer that has a pattern recorded therein that is conforming to a shape of the surface of the mold in contact with the liquid. The mold is then separated from the patterned layer such that the mold and the substrate are spaced-apart. The substrate and the patterned layer are then subjected to processes to transfer, into the substrate, a relief image that corresponds to the pattern in the patterned layer.

DETAILED DESCRIPTION

Referring toFIG. 1, a system10to form a relief pattern on a substrate12is shown. Substrate12may be coupled to a substrate chuck14. Substrate chuck14may be any chuck including, but not limited to, vacuum, pin-type, groove-type, or electromagnetic, as described in U.S. Pat. No. 6,873,087 entitled “High-Precision Orientation Alignment and Gap Control Stages for Imprint Lithography Processes,” which is incorporated herein by reference. Substrate12and substrate chuck14may be supported upon a stage16. Further, stage16, substrate12, and substrate chuck14may be positioned on a base (not shown). Stage16may provide motion about the x and y axes.

Spaced-apart from substrate12is a template18having a mold20extending therefrom towards substrate20with a patterning surface22thereon. Further, mesa20may be referred to as a mold20. Mesa20may also be referred to as a nanoimprint mold20. In a further embodiment, template18may be substantially absent of mold20. Template18and/or mold20may be formed from such materials including but not limited to, fused-silica, quartz, silicon, organic polymers, siloxane polymers, borosilicate glass, fluorocarbon polymers, metal, and hardened sapphire. As shown, patterning surface22comprises features defined by a plurality of spaced-apart recesses24and protrusions26. However, in a further embodiment, patterning surface22may be substantially smooth and/or planar. Patterning surface20may define an original pattern that forms the basis of a pattern to be formed on substrate12.

Template18may be coupled to a template chuck28, template chuck28being any chuck including, but not limited to, vacuum, pin-type, groove-type, or electromagnetic, as described in U.S. Pat. No. 6,873,087 entitled “High-Precision Orientation Alignment and Gap Control Stages for Imprint Lithography Processes”. Template chuck28may be coupled to an imprint head30to facilitate movement of template18and mold20.

System10further comprises a fluid dispense system32. Fluid dispense system32may be in fluid communication with substrate12so as to deposit a polymeric material34thereon. System10may comprise any number of fluid dispensers and fluid dispense system32may comprise a plurality of dispensing units therein. Polymeric material34may be positioned upon substrate12using any known technique, e.g., drop dispense, spin-coating, dip coating, chemical vapor deposition (CVD), physical vapor deposition (PVD), thin film deposition, thick film deposition, and the like. As shown, polymeric material34may be deposited upon substrate12as a plurality of spaced-apart droplets36. Typically, polymeric material34is disposed upon substrate12before the desired volume is defined between mold20and substrate12. However, polymeric material34may fill the volume after the desired volume has been obtained.

Referring toFIGS. 1 and 2, system10further comprises a source38of energy40coupled to direct energy40along a path42. Imprint head30and stage16are configured to arrange mold20and substrate12, respectively, to be in superimposition and disposed in path42. Either imprint head30, stage16, or both vary a distance between mold20and substrate12to define a desired volume therebetween such that mold20contacts polymeric material34and the desired volume is filled by polymeric material34. More specifically, polymeric material34of droplets36may ingress and fill recesses24of mold20. After the desired volume is filled with polymeric material34, source38produces energy40, e.g., broadband ultraviolet radiation that causes polymeric material34to solidify and/or cross-link conforming to the shape of a surface44of substrate12and patterning surface22, defining a patterned layer46on substrate12. Patterned layer46may comprise a residual layer48and a plurality of features shown as protrusions50and recessions52. System10may be regulated by a processor54that is in data communication with stage16, imprint head30, fluid dispense system32, and source38, operating on a computer readable program stored in memory56.

Referring toFIGS. 1 and 3, substrate12may comprise a plurality of fields, shown as fields a-d. However, in a further embodiment, substrate12may comprise any number of fields. Each of fields a-d of substrate12may be subjected to the aforementioned patterning process. In a first embodiment, all of fields a-d of substrate12may have polymeric material34positioned thereon concurrently by fluid dispense system32. In a further embodiment, polymeric material34may be positioned on fields a-d of substrate12sequentially by fluid dispense system32. Fields a-d of substrate12may have a volume Vdispensepositioned thereon by fluid dispense system32.

Polymeric material34positioned on each of fields a-d of substrate12may fill the desired volume between mold20and substrate12, and more specifically, ingress and fill recesses24of mold20, as described above. Mold20may contact polymeric material34positioned on each of fields a-d of substrate12sequentially. More specifically, mold20may contact polymeric material34positioned on field a of substrate12prior to contacting fields b-d of substrate12; mold20may contact polymeric material34positioned on field b of substrate12after contacting field a of substrate12and prior to contacting fields c-d of substrate12contact mold20; mold20may contact polymeric material34positioned on field c of substrate12after contacting field b of substrate12and prior to contacting field d of substrate12; and mold20may contact polymeric material34positioned on field d of substrate12after contacting field c of substrate12. In a further embodiment, any desired sequential order of contacting polymeric material34on fields a-d of substrate may be employed.

As a result of mold20contacting polymeric material34positioned on fields a-d of substrate12sequentially, each of fields a-d of substrate12may be subjected to differing evaporation times. More specifically, a time between positioning polymeric material34on a field a-d of substrate12and mold20contacting polymeric material34on the field a-d of substrate12may be referred to as an “evaporation time” of polymeric material34positioned on the field a-d of substrate12. To that end, a volume of polymeric material34positioned on a field a-d of substrate12upon contact with mold20may differ from a volume of polymeric material34positioned on the field a-d of substrate12by fluid dispense system32. This may result from, inter alia, the evaporation time associated with fields a-d of substrate12. To that end, polymeric material34positioned on field a of substrate12may have a first evaporation time Taassociated therewith resulting in the volume of polymeric material34positioned on field a upon contact with mold20being VevapA, with VevapAbeing less than Vdispense; polymeric material34positioned on field b of substrate12may have a second evaporation time Tbassociated therewith resulting in the volume of polymeric material34positioned on field b upon contact with mold20being VevapB, with VevapBbeing less than Vdispense; polymeric material34positioned on field c of substrate12may have a third evaporation time Tcassociated therewith resulting in the volume of polymeric material34positioned on field c upon contact with mold20being VevapC, with VevapCbeing less than Vdispense; and polymeric material34positioned on field d of substrate12may have a fourth evaporation time Tdassociated therewith resulting in the volume of polymeric material34positioned on field d upon contact with mold20being VevapD, with VevapDbeing less than Vdispense.

As mentioned above, mold20contacts fields a-d of substrate12sequentially. Thus, polymeric material34on a first subset of fields a-d of substrate12that are contacted by mold20subsequent to polymeric material34on a second subset of fields a-d of substrate12, differing from the first subset, being contacted by mold20will have a greater evaporation time associated therewith. More specifically, evaporation time Tbmay be greater than evaporation time Ta; evaporation time Tcmay be greater than evaporation time Tb; and evaporation time Tdmay be greater than evaporation time Tc. In summary, evaporation times Ta, Tb, Tc, and Tdmay be defined as follows:
Td>Tc>Tb>Ta.   (1)

As a result of the evaporation time being greater for polymeric material34on the aforementioned first subset of fields a-d of substrate12compared to the evaporation time for polymeric material34on the aforementioned second subset of fields a-d of substrate12, the volume of polymeric material34on the aforementioned second subset of fields a-d of substrate12upon contact with mold20will be greater than the volume of polymeric material34on the aforementioned first subset of fields a-d of substrate12upon contact with mold20. More specifically, volume VevapAof polymeric material34on field a of substrate12upon contact with mold20is greater than VevapBof polymeric material34on field b of substrate12upon contact with mold20; volume VevapBof polymeric material34on field b of substrate12upon contact with mold20is greater than VevapCof polymeric material34on field c of substrate12upon contact with mold20; and volume VevapCof polymeric material34on field c of substrate12upon contact with mold20is greater than VevapDof polymeric material34on field d of substrate12upon contact with mold20. In summary, volumes VevapA, VevapB, VevapC, and VevapD, of polymeric material34on fields a, b, c, and d, respectively, of substrate12, upon contact with mold20, may be defined as follows:
VevapA>VevapB>VevapC>VevapD.   (2)

Referring toFIGS. 1-3, to that end, contacting polymeric material34positioned on fields a-d of substrate12with mold20each having a differing volume associated therewith, may result in pattern distortion of features formed from polymeric material34in patterned layer46; low fidelity of features form from polymeric material34in patterned layer46, and a non-uniform thickness of residual layer48across patterned layer46, all of which are undesirable.

Referring toFIGS. 1 and 3, to compensate for the evaporation of polymeric material34positioned on fields a-d of substrate12, the volume Vdispensepositioned on each of fields a-d of substrate12by fluid dispense system32may be varied. More specifically, the volume Of Vdispensepositioned on the aforementioned first subset of fields a-d of substrate12by fluid dispense system32may be increased as compared to the volume Vdispensepositioned on the aforementioned second subset of fields a-d of substrate12by fluid dispense system32. As a result, upon contact with mold20, each of fields a-d of substrate12may have substantially the same volume of polymeric material34, which may be desired.

More specifically, the volume VdispenseDpositioned on field d of substrate12by fluid dispense system32is greater than the volume VdispenseCpositioned on field c of substrate12by fluid dispense system32; the volume VdispenseCpositioned on field c of substrate12by fluid dispense system32is greater than the volume VdispenseBpositioned on field b of substrate12by fluid dispense system32; and the volume VdispenseBpositioned on field b of substrate12by fluid dispense system32is greater than the volume VdispenseApositioned on field a of substrate12by fluid dispense system32. In summary, volumes VdispenseA, VdispenseB, VdispenseC, and VdispenseD, of polymeric material34on fields a, b, c, and d, respectively, positioned on substrate12by fluid dispense system32may be defined as follows:
VdispenseD>VdispenseC>VdispenseB>VdispenseA(3)

As a result of positioning polymeric material32on field a having a volume VdispenseAand subjecting polymeric material32on field a of substrate12to evaporation time Ta, the volume of polymeric material32on field a of substrate12upon contact with mold20is VfinalA; as a result of positioning polymeric material32on field b having a volume VdispenseBand subjecting polymeric material32on field b of substrate12to evaporation time Tb, the volume of polymeric material32on field b of substrate12upon contact with mold20is VfinalB; as a result of positioning polymeric material32on field c having a volume VdispenseCand subjecting polymeric material32on field c of substrate12to evaporation time Tc, the volume of polymeric material32on field c of substrate12upon contact with mold20is VfinalC; and as a result of positioning polymeric material32on field d having a volume VdispenseDand subjecting polymeric material32on field d of substrate12to evaporation time Td, the volume of polymeric material32on field d of substrate12upon contact with mold20is VfinalD. To that end, the volumes VfinalA, VfinalB, VfinalC, and VfinalDof polymeric material32positioned on fields a, b, c, and d, respectively of substrate upon contact with mold20may be all substantially the same.

Referring toFIGS. 1-3, to determine the volumes VdispenseA, VdispenseB, VdispenseC, and VdispenseDof polymeric material34positioned on fields a-d of substrate12, respectively, direct imaging of polymeric material34in droplets40positioned on each field a-d of substrate12may be employed. In a further embodiment, film thickness metrology of patterned layer46may be employed.

Referring toFIG. 1, in a further embodiment, after mold20contacts polymeric material34on a field a-d of substrate12, source38may produce energy40to cause polymeric material34to be solidified and/or cross-linked, as mentioned above. However, polymeric material34positioned on surrounding fields a-d of substrate12may be concurrently exposed to energy40, and thus, may be solidified and/or cross-linked prior to contact with mold20, which is undesirable. Solidifying and/or cross-linking of polymeric material34positioned on the surrounding fields a-d of substrate12may result in, inter alia, problematic control of the thickness of subsequently disposed layers on the surrounding fields a-d of substrate12and formation of deleterious artifacts in layers formed on the surrounding fields a-d of substrate12, all of which are undesirable. To that end, a method of patterning substrate12to minimize, if not prevent, undesired curing and/or cross-linking of polymeric material32on surrounding fields a-d of substrate12is described further below.

Referring toFIGS. 1 and 4, substrate12is shown have a plurality of fields w-z. Each field w-z of substrate12comprises a plurality of sub-fields, i.e., field w of substrate12comprises sub-fields w1-w4; field x of substrate12comprises sub-fields x1-x4; field y of substrate12comprises sub-fields y1-y4; and field z of substrate12comprises sub-fields z1-z4. Each sub-field of a field w-z of substrate12may be spaced-apart from the remaining sub-fields of the field w-z of substrate12by the remaining fields w-z of substrate12. More specifically, each sub-field w1-w4of field w of substrate12may be separated from the remaining sub-fields w1-w4of field w of substrate12by fields x-z; each sub-field x1-x4of field x of substrate12may be separated from the remaining sub-fields x1-x4of field x of substrate12by fields w, y, and z; each sub-field y1-y4of field y of substrate12may be separated from the remaining sub-fields y1-y4of field y of substrate12by fields w, x, and z; and each sub-field z1-z4of field z of substrate12may be separated from the remaining sub-fields z1-z4of field z of substrate12by fields w-y.

Referring toFIGS. 1,4, and5, a process flow for patterning substrate12having fields w-z is shown. At step100, polymeric material34may be positioned on field w using any of the techniques mentioned above. Polymeric material28may be positioned on field w concurrently by fluid dispense system32, or in a further embodiment, polymeric material34may be positioned on sub-fields w1-w4of field w of substrate12sequentially by fluid dispense system32.

At step104, polymeric material34may be positioned on field x using any of the techniques mentioned above. Polymeric material28may be positioned on field x concurrently by fluid dispense system32, or in a further embodiment, polymeric material34may be positioned on sub-fields x1-x4of field x of substrate12sequentially by fluid dispense system32.

At step108, polymeric material34may be positioned on field y using any of the techniques mentioned above. Polymeric material28may be positioned on field y concurrently by fluid dispense system32, or in a further embodiment, polymeric material34may be positioned on sub-fields y1-y4of field y of substrate12sequentially by fluid dispense system32.

At step112, polymeric material34may be positioned on field z using any of the techniques mentioned above. Polymeric material28may be positioned on field z concurrently by fluid dispense system32, or in a further embodiment, polymeric material34may be positioned on sub-fields z1-z4of field w of substrate12sequentially by fluid dispense system32.

The embodiments of the present invention described above are exemplary. Many changes and modifications may be made to the disclosure recited above, while remaining within the scope of the invention. Therefore, the scope of the invention should not be limited by the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents.