ASSEMBLY AND METHOD FOR TRANSFERRING IMPRINT LITHOGRAPHY TEMPLATES
Disclosed is a template transfer assembly and method that features a template transfer substrate, and a template having first and second sides, with the first side facing away from the template transfer substrate and the second side facing the template transfer substrate and having mold pattern formed thereon. Polymerized imprint material is disposed between the second side and the template transfer substrate to fixedly attach the template to the template transfer substrate. The method of transferring an imprint lithography template includes dispensing a selected volume of imprinting fluid onto the template transfer substrate, placing the template upon the selected volume; and converting the imprinting fluid to solid imprint material. The selected volume of imprint material is of sufficient quantity to fixedly attach the template to the template transfer substrate while maintaining a space between the mold and the template transfer substrate.
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The present invention relates generally to imprint lithography. More particularly, the present invention is directed to an assembly and method to transfer templates during imprint lithography processes.
Micro-fabrication techniques can produce structures having features on the order of nanometers. Micro-fabrication is used in a wide variety of applications, such as the manufacturing of integrated circuits (i.e. semiconductor processing), biotechnology, optical technology, mechanical systems, and micro-electro-mechanical systems (“MEMS”).
Imprint lithography is a type of micro-fabrication technique that is becoming increasingly important in semiconductor processing and other applications. Imprint lithography provides greater process control and reduction of the minimum feature dimension of the structures formed. This in turn provides higher production yields and more integrated circuits per wafer, for example.
Micro-fabrication can be used to form a relief image on a substrate, such as a semiconductor wafer. The substrate typically has a transfer layer that is coated with a thin layer of polymerizable fluid, thermoplastic, or other imprint material capable of being formed (i.e. molded or imprinted) into a desired structure. A mold with a relief structure makes mechanical contact with the substrate and the polymerizable fluid or other imprint material fills the relief structure of the mold. The polymerizable fluid is then polymerized to form the desired structure on the transfer layer, which is complimentary to the relief structure of the mold. The transfer layer and the solidified polymeric material can then be etched to form a relief image in the transfer layer, or coated with a thin-film layer of other material, for example.
Imprint lithography systems often use an imprint head with a mold, also called a template, which can be installed and removed from the imprint head. This allows the imprint lithography system to be used to imprint different patterns. In this manner, the imprint lithography system can be used to fabricate various types of circuits or other devices, or imprint various structures on a substrate.
To ensure high resolution imprinting it is generally desirable to minimize handling of the template in order to avoid damage to the template and contamination to the template and imprint lithography system with dust or other particulates. To that end, there is a need to store, load, and unload templates in a manner that avoids physical damage to the relief pattern of the mold and contamination to the template and imprint lithography system.
SUMMARY OF THE INVENTIONA template transfer assembly and method features a template transfer substrate and a template having first and second sides, with the first side facing away from the template transfer substrate and the second side facing the template transfer substrate and having mold pattern formed thereon. Polymerized imprint material is disposed between the second side and the template transfer substrate to fixedly attach the template to the template transfer substrate. The method of transferring an imprint lithography template includes dispensing a selected volume of imprinting fluid onto the template transfer substrate, placing the template upon the selected volume and converting the imprinting fluid to solid imprint material. The selected volume of imprint material is of sufficient quantity to fixedly attach the template to the template transfer substrate while maintaining a space between the mold and the template transfer substrate. These and other embodiments are described more fully below.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring to both
An imprinting layer 34 is disposed on wafer 30. Imprinting layer 34 is generally a selected volume of imprint material, such as polymerizable fluid, applied to wafer 30, either as a plurality of spaced-apart beads 36, as shown, or in a continuous film. Exemplary imprint material is described in U.S. patent application Ser. No. 10/178,947, filed Jun. 24, 2002 and entitled “Low Viscosity High Resolution Patterning Material”, which is incorporated by reference herein in its entirety. An exemplary method and system for depositing the imprint material is disclosed in U.S. patent application Ser. No. 10/191,749, filed Jul. 2, 2002 and entitled “System and Method for Dispensing Liquids”, which is incorporated by reference herein in its entirety.
Referring to
Mold 28 has features sized according to the structure 28′ desired to be imprinted to imprinting layer 34′, which can be on the order of nanometers. It is important to protect mold 28 from physical damage and/or contamination so that the desired structure 28′ is obtained when imprinting substrates. Template 26 is removable from imprint head 18 of imprint lithography system 10, shown in
Template 26 is removably secured to imprint head 18 with vacuum and/or mechanical means, such as pins or clips. Mechanical means are desirable to ensure retention of template 26 in imprint head 18 in the event of a vacuum failure or in the event that vacuum is turned off during processing. Mechanical means of securing template 26 in imprint head 18 may also be convenient when installing or removing template 26.
To facilitate coupling template 26 to imprint head 18, the template 26 is typically stored on template transfer system 40 so that first side 26a faces imprint head 18. When coupling together template 26 and imprint head 18, template 26 and imprint head 18 are placed in very close proximity (e.g. 10's of microns or less) to one another so that the template 26 can be secured to imprint head 18 by vacuum and/or mechanical contact. Manual insertion of the template 26 into imprint head 18 is typically avoided due to the increased probability of damage to the template 26 and/or imprint head 18, as well as the increased probability of contamination of the imprint lithography system 10, particularly the motion stage 20.
Referring to
It is generally desirable that template transfer system 40 be located in a position on motion stage 20 that allows template transfer system 40 to be brought to a convenient position for loading template 26 into template transfer system 40, and then to be brought underneath imprint head 18 without compromising wafer imprinting. Many motion stages have a range of motion greater than the range required to imprint the entire surface of a wafer 30, shown in
Referring to
After loading template 26 into imprint head 18, the relative positions of imprint head 18 and motion stage 20 are established to imprint a wafer (not shown) loaded onto wafer chuck 21. Upon completion of imprinting processes, template 26 may be removed from imprint head 18 by reversing the sequence of loading steps, and load another template into imprint head 18, if desired.
Referring to
Template transfer holder 40a includes a body 50 having a plurality of tines 52 extending from a common side 54 of body 50. Also protruding from side 54 is a plurality of compliant members 56, each of which has a throughway 58. Throughway 58 is in fluid communication with a channel 60, shown in
Referring to
Referring to both
Referring to
As a result of compression of template 26 against compliant members 56, a perimeter region 26d of template 26 bears against detent 53c and moves along the Z axis about pivot point 53e. Member arm 53f cantilevers toward surface 52a causing end tines 52 to move inwardly toward template 26 until template edge 26c is compressed by ends 52c. Each of tines 52 is arranged to move approximately the same extent as the remaining tines 52 on body 50. The free movement of detent 56b and boss 56c along X and Y axes, as well as the movement of tines 52, results in template 26 being placed at a predefined location on body 50, each time template 26 is loaded thereon. In the present example, template 26 is centered on body 50. This is referred to as the final seating position. In the final seating position, mold 28 is spaced-apart from side 54. To that end, gap 53d is provided with a height h1, and mold 28 extends from side 26b having a height, h2. Heights h1 and h2 are established to ensure that upon reaching the final seating position mold 28 does not contact surface 52a. Thus, the structural integrity of mold 28 is preserved, while allowing template 26 to be removed and inserted into template transfer holder 40a with imprint head 18, shown in
Referring to
Template transfer system 140 can be located anywhere on transfer substrate 144 accessible by the imprint head 18. Motion stage 20 does not need additional motion range to position template transfer system 140 under imprint head 18. Contamination of wafer chuck 21 by the backside of transfer substrate 144 may be reduced by proper handling of transfer substrate 144.
Referring to
Referring to
When it is desired to unload and store template 326 from imprint head 18 (e.g. after imprinting a run of process wafers), template transfer substrate 344 is mounted on wafer chuck 21. A selected volume of imprinting material is applied in a fluid state to the region of template transfer substrate 344 that template 326 will be attached to. The volume of fluid may be less than, the same as, or greater than the volume of imprinting material that would be used to imprint a production wafer.
Template 326 is brought into contact with the imprinting material, and the imprinting material is polymerized or otherwise solidified fixedly affixing template 326 to template transfer substrate 344. Rather than increasing a distance between the imprint head 18 and the wafer chuck 21, vacuum and/or mechanical retaining means may be deactivated to release template 326 from the imprint head 18. Template 326 adheres to template transfer substrate 344 with solid imprint material 334, and may be moved therewith to a remote storage location.
Alternatively, template transfer substrate 344 may be left on the wafer chuck 21 and template 326 is removed from or retained in the imprint head 18. In each case, solid imprint material 334 protects the mold pattern 328 on template 326 when not in use. Solid imprint material 334 seals template 326 from contamination and the mold pattern 328 on the face of template 326 is protected from damage. This may be achieved by covering the entire area of mold pattern 328 with the imprint material 334, thereby hermetically sealing mold pattern 328.
When template 326 is removed from the imprint head 18 for storage again, a new or reworked template transfer substrate is used. Alternatively, the same substrate may be employed to store template 326, but the template 326 would be stored in a differing region thereof. A template transfer substrate 344 is reworked by removing solid imprint material 334 from template transfer substrate 344. Process wafers rejected before imprinting are often convenient for use as template transfer substrates 344.
Alternatively, as shown in
When it is desired to store template 426, the same may be attached to template transfer substrate 444 with solid imprint material 434 to fixedly attach template transfer substrate 444 to template 426. To that end, template transfer substrate 444, having imprinting material 434, is loaded onto the wafer chuck 21 and template 426 is moved to a position underneath the imprint head 18 (if not already loaded). Relative movement between the imprint head 18 and template 426 is achieved to reduce the spacing therebetween, placing the imprint head 18 and the template 426 in close proximity or contact. The template 426 is secured to the imprint head 18 by means of a vacuum and/or mechanical coupling. The imprint head 18, along with template 426 is placed in superimposition with template transfer substrate 444. Thereafter, contact is made between template 426 and imprint material 434 present on template transfer substrate 444. The imprint material 434 is then solidified, as discussed above, securely affixing template 426 to template transfer substrate 444.
Referring to
To store template 526 on template transfer substrate 544, a selected volume of imprinting material 534 is applied in a fluid state to a surface 531 of template transfer substrate 544. The imprinting material 534 may be applied to a selected area (e.g. an area corresponding to the perimeter of template 526), or the volume of imprinting material 534 is selected to adhere to the perimeter mesa 536 only, and to not fill in areas of mold pattern 528 on template 526. Recess 537 prevents fluid imprinting material 534 from reaching mold pattern 528 when mechanical contact is made between the imprinting material 534 and template 526.
To store template 626 a selected volume of imprinting material 634 is applied in a fluid state to a surface 631 of template transfer substrate 644. The imprinting material 634 is applied to a region of surface 631 that will be in superimposition with surface 638. The volume of imprinting material 634 typically selected is sufficient to adhere template 626 to the template transfer substrate 644 so that mold pattern 628 is spaced-apart from surface 631. Although it is not necessary, imprinting material 634 may circumscribe mold pattern 628, thereby encapsulating the same to prevent contamination by particulate matter.
Referring to
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 be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents.
Claims
1. A template transfer assembly comprising:
- a template transfer substrate;
- a template having first and second sides, with said first side facing away from said template transfer substrate and said second side facing said template transfer substrate and having a mold pattern formed thereon; and
- polymerized imprint material disposed between said second side and said template transfer substrate to fixedly attach said template to said template transfer substrate.
2. The template transfer assembly as recited in claim 1 wherein said polymerized imprint material surrounds a sub-section of said mold.
3. The template transfer assembly as recited in claim 1 wherein said polymerized imprint material hermetically seals a sub-portion of said mold.
4. The template transfer assembly as recited in claim 1 wherein said polymerized imprint material surrounds said entire mold.
5. The template transfer assembly as recited in claim 1 wherein said polymerized imprint material encapsulates said entire mold hermetically sealing said mold from an ambient.
6. The template transfer assembly as recited in claim 1 wherein said template further includes a perimeter groove surrounding said mold with said polymerized imprint material disposed between said template transfer substrate and a region of said second side that is in superimposition with said perimeter groove.
7. The template transfer assembly as recited in claim 1 wherein said template transfer substrate comprises a semiconductor wafer.
8. The template transfer assembly as recited in claim 1 wherein said template transfer substrate includes a semiconductor wafer having an additional template coupled thereto.
9. A template transfer assembly comprising:
- a template transfer substrate;
- a template having first and second sides, with said first side facing away from said template transfer substrate and said second side facing said template transfer substrate and having a mold formed thereon; and
- polymerized imprint material disposed between said second side and said template transfer substrate to fixedly polymerized imprint material disposed between said second side and said template transfer substrate to fixedly attach said template to said template transfer substrate while maintaining a space between said mold and said template transfer substrate.
10. The template transfer assembly as recited in claim 9 wherein said space is filled with imprint material.
11. The template transfer assembly as recited in claim 9 wherein a sub-portion of said space defines a void between said substrate and a sub-section of said mold.
12. The template transfer assembly as recited in claim 11 wherein said polymerized imprint material surrounds said void.
13. The template transfer assembly as recited in claim 9 wherein said polymerized imprint material hermetically seals a sub-portion of said mold.
14. The template transfer assembly as recited in claim 11 wherein said void is coextensive with said mold.
15. The template transfer assembly as recited in claim 9 wherein said polymerized imprint material encapsulates said entire mold hermetically sealing said mold from an ambient.
16. A method of transferring an imprint lithography template, said method comprising:
- providing a template transfer substrate;
- forming a selected volume of imprinting fluid onto said template transfer substrate;
- placing said template upon said selected volume; and
- converting said imprinting fluid to solid imprint material, with said selected volume being a quantity sufficient to fixedly attach said template to said template transfer substrate while maintaining a space between a mold and said template transfer substrate.
17. The method as recited in claim 16 wherein converting further includes urging said template upon said selected volume so that, upon converting said imprint material, said solid imprint material surrounds a portion of said mold.
18. The method as recited in claim 10 wherein converting further includes urging said template upon said selected volume so that, upon converting said imprint material, said solid imprint material hermetically seals a sub-portion of said mold.
19. The method as recited in claim 10 wherein converting further includes urging said template upon said selected volume so that, upon converting said imprint material, said solid imprint material surrounds said mold, entirely.
20. The method as recited in claim 10 wherein converting further includes urging said template upon said selected volume so that, upon converting said imprint material, said solid imprint material encapsulates said mold, hermetically sealing said mold from an ambient.
Type: Application
Filed: May 14, 2003
Publication Date: Sep 29, 2005
Applicant: MOLECULAR IMPRINTS, INC (Austin, TX)
Inventors: Mario Meissl (Austin, TX), Byung Choi (Round Rock, TX)
Application Number: 10/437,476