The field of invention relates generally to lithography systems. More particularly, the present invention is directed to reducing undesirable pattern variations during imprint lithography processes.
Micro-fabrication involves the fabrication of very small structures, e.g., having features on the order of micro-meters or smaller. One area in which micro-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, micro-fabrication becomes increasingly important. Micro-fabrication provides greater process control while allowing increased reduction of the minimum feature dimension of the structures formed. Other areas of development in which micro-fabrication has been employed include biotechnology, optical technology, mechanical systems and the like.
An exemplary micro-fabrication technique is shown in U.S. Pat. No. 6,334,960 to Willson et al. Willson et al. disclose a method of forming a relief image in a structure. The method includes providing a substrate having a transfer layer. The transfer layer is covered with a polymerizable fluid composition. A mold makes mechanical contact with the polymerizable fluid. The mold includes a relief structure, and the polymerizable fluid composition fills the relief structure. The polymerizable fluid composition is then subjected to conditions to solidify and polymerize the same, forming a solidified polymeric material on the transfer layer that contains a relief structure complimentary to that of the mold. The mold is then separated from the solid polymeric material such that a replica of the relief structure in the mold is formed in the solidified polymeric material. The transfer layer and the solidified polymeric material are subjected to an environment to selectively etch the transfer layer relative to the solidified polymeric material such that a relief image is formed in the transfer layer. The time required and the minimum feature dimension provided by this technique is dependent upon, inter alia, the composition of the polymerizable material.
U.S. Pat. No. 5,772,905 to Chou discloses a lithographic method and apparatus for creating ultra-fine (sub-36 nm) patterns in a thin film coated on a substrate in which a mold having at least one protruding feature is pressed into a thin film carried on a substrate. The protruding feature in the mold creates a recess in the thin film. The mold is removed from the film. The thin film then is processed such that the thin film in the recess is removed exposing the underlying substrate. Thus, patterns in the mold are replaced in the thin film, completing the lithography. The patterns in the thin film will be, in subsequent processes, reproduced in the substrate or in another material which is added onto the substrate.
Yet another imprint lithography technique is disclosed by Chou et al. in Ultrafast and Direct Imprint of Nanostructures in Silicon, Nature, Col. 417, pp. 835-837, June 2002, which is referred to as a laser assisted direct imprinting (LADI) process. In this process a region of a substrate is made flowable, e.g., liquefied, by heating the region with the laser. After the region has reached a desired viscosity, a mold, having a pattern thereon, is placed in contact with the region. The flowable region conforms to the profile of the pattern and is then cooled, solidifying the pattern into the substrate. An important consideration when forming patterns in this manner is to maintain control of the mold. In this fashion, undesirable variations in the pattern resulting from, inter alia, undesired deformation of the mold may be avoided. For example, in-plane distortion can cause line width variations, as well as pattern placement errors. Out-of-plane distortion can cause loss of focus in optical lithography resulting in varying the thickness of underlying residual layers. This may make difficult both line width control and etch transfer.
It is desired, therefore, to provide improved techniques for holding the mold so as to properly position the same with respect to the substrate upon which a pattern is to be formed.
The present invention is directed to a chucking system to modulate substrates so as to properly shape a mold and position the same with respect to a wafer upon which a pattern is formed using the mold. The chucking system includes a chuck body having first and second opposed sides with a side surface extending therebetween. The first side includes first and second spaced-apart recesses defining first and second spaced-apart support regions. The first support region cinctures the second support region and the first and second recesses. The second support region cinctures the second recess, with a portion of the body in superimposition with the second recess being transparent to radiation having a predetermined wavelength. The portion extends from the second side and terminates proximate to the second recess. The second side and the side surface define exterior surfaces. The body includes first and second throughways extending through the body placing the first and second recesses, respectively, in fluid communication with one of the exterior surfaces.
In another embodiment, a pressure control system is included. The first throughway places the first recess in fluid communication with the pressure control system and the second throughway places the pressure control system in fluid communication with the second recess. When mounted to the chuck body, the substrate rests against the first and second support regions, covering the first and second recesses. The first recess and the portion of the substrate in superimposition therewith define a first chamber and the second recess and the portion of the substrate in superimposition therewith defines a second chamber. The pressure control system operates to control a pressure in the first and second chambers. Specifically, the pressure is established in the first chamber to maintain the position of the substrate with the chuck body. The pressure in the second chamber may differ from the pressure in the first chamber to, inter alia, reduce distortions in the substrate that occur during imprinting. These and other embodiments of the present invention are discussed more fully below.
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To facilitate filling of recessions 28a, material 36a is provided with the requisite properties to completely fill recessions 28a while covering surface 32 with a contiguous formation of material 36a. In the present embodiment, sub-portions 34b of imprinting layer 34 in superimposition with protrusions 28b remain after the desired, usually minimum distance “d”, has been reached, leaving sub-portions 34a with a thickness t1, and sub-portions 34b with a thickness, t2. Thicknesses “t1” and “t2” may be any thickness desired, dependent upon the application. Typically, t1 is selected so as to be no greater than twice the width u of sub-portions 34a, i.e., t1≦2 u, shown more clearly in FIG. 5.
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It should be understood that throughway 64 may extend between second side 48 and first recess 52, as well. Similarly, throughway 66 may extend between second side 48 and second recess 54. What is desired is that throughways 64 and 66 facilitate placing recesses 52 and 54, respectively, in fluid communication with a pressure control system, such a pump system 70.
Pump system 70 may include one or more pumps to control the pressure proximate to recesses 52 and 54, independently of one another. Specifically, when mounted to chuck body 42, substrate 26 rests against first 58 and second 60 support regions, covering first 52 and second 54 recesses. First recess 52 and a portion 44a of substrate 26 in superimposition therewith define a first chamber 52a. Second recess 54 and a portion 44b of substrate 26 in superimposition therewith define a second chamber 54a. Pump system 70 operates to control a pressure in first 52a and second 54a chambers. Specifically, the pressure is established in first chamber 52a to maintain the position of the substrate 26 with the chuck body 42 and reduce, if not avoid, separation of substrate 26 from chuck body 42 under force of gravity. The pressure in the second chamber 54a may differ from the pressure in the first chamber 52a to, inter alia, reduce distortions in the substrate 26 that occur during imprinting, by modulating a shape of substrate 26. For example, pump system 70 may apply a positive pressure in chamber 54a to compensate for any upward force R that occurs as a result on imprinting layer 34 contacting mold 28. In this manner, produced is a pressure differential between differing regions of side 46 so that bowing of substrate 26 and, therefore, mold 28 under force R is attenuated, if not avoided.
Coupled to substrate 26 is a means to compress the same in X and Y directions, with the understanding that the Y-direction is into the plane of FIG. 8. In the present example the means to compress includes a fluid-tight bladder 72 surrounding substrate 26; however, any device may be employed to that end, for example, a vice. Bladder 72 is in fluid communication with pump system 70 to control the fluid pressure in bladder 72. In this manner, bladder 72 may be used to apply a force to substrate 26 to vary the dimensions of the same and reduce distortions in the pattern recorded into imprinting layer 34, shown in FIG. 2.
Specifically, distortions in the pattern recorded into imprinting layer 34 may arise from, inter alia, dimensional variations of imprinting layer 34 and wafer 30. These dimensional variations, which may be due in part to thermal fluctuations, as well as, inaccuracies in previous processing steps that produce what is commonly referred to as magnification/run-out errors. The magnification/run-out errors occur when a region of wafer 30 in which the original pattern is to be recorded exceeds the area of the original pattern. Additionally, magnification/run-out errors may occur when the region of wafer 30, in which the original pattern is to be recorded, has an area smaller than the original pattern. The deleterious effects of magnification/run-out errors are exacerbated when forming multiple layers of imprinted patterns, shown as imprinting layer 124 in superimposition with patterned surface 32a, shown in FIG. 6. Proper alignment between two superimposed patterns is difficult in the face of magnification/run-out errors in both single-step full wafer imprinting and step-and-repeat imprinting processes.
Referring to
However, in accordance with one embodiment of the present invention, magnification/run-out errors are reduced, if not avoided, by creating relative dimensional variations between mold 28 and wafer 30. Specifically, the temperature of wafer 30 is varied so that one of regions a-l defines an area that is slightly less than an area of the original pattern on mold 28. Thereafter, the final compensation for magnification/run-out errors is achieved by subjecting substrate 26, shown in
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In yet another embodiment, shown in
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Specifically, a change in the distance between two gross alignment fiducials 110b collinear along one of the X or Y axes is determined. Thereafter, this change in distance is divided by a number of adjacent regions a-l on the wafer 30 along the X-axis. This provides the dimensional change of the areas of regions a-l attributable to dimensional changes in wafer 30 along the X-axis. If necessary the same measurement may be made to determine the change in area of regions a-l due to dimensional changes of wafer 30 along the Y-axis. However, it may also be assumed that the dimensional changes in wafer 30 may be uniform in the two orthogonal axes, X and Y.
At step 204, compressive forces, F1 and F2, are applied to mold 28 to establish the area of the original pattern to be coextensive with the area of one of the regions a-l in superimposition with the pattern. This may be achieved in real-time employing machine vision devices (not shown) and known signal processing techniques, to determine when two or more of alignment marks 114a are aligned with two or more of fiducial marks 110a. At step 206, after proper alignment is achieved and magnification/run-out errors are reduced, if not vitiated, the original pattern is recorded in the region a-l that is in superimposition with mold 28, forming the recorded pattern. It is not necessary that compression forces F1 and F2 have the same magnitude, as the dimensional variations in either wafer 30 or mold 28 may not be uniform in all directions. Further, the magnification/run-out errors may not be identical in both X-Y directions. As a result, compression forces, F1 and F2 may differ to compensate for these anomalies. Furthermore, to ensure greater reduction in magnification/run-out errors, the dimensional variation in mold 28 may be undertaken after mold 28 contacts imprinting layer 124, shown in FIG. 6. However, this is not necessary.
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Were it determined at step 304 that the region a-l in superimposition with mold 28 had an area greater than the area of the pattern, then the process proceeds to step 306 wherein the temperature of mold 28 is varied to cause expansion of the same. In the present embodiment, mold 28 is heated at step 306 so that the pattern is slightly larger than the area of region a-l in superimposition therewith. Then the process continues at step 310.
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. For example, by pressurizing all chambers formed by the chuck body-substrate combination with positive fluid pressure, the substrate may be quickly released from the chuck body. Further, many of the embodiments discussed above may be implemented in existing imprint lithography processes that do not employ formation of an imprinting layer by deposition of beads of polymerizable material. Exemplary processes in which differing embodiments of the present invention may be employed include a hot embossing process disclosed in U.S. Pat. No. 5,772,905, which is incorporated by reference in its entirety herein. Additionally, many of the embodiments of the present invention may be employed using a laser assisted direct imprinting (LADI) process of the-type described by Chou et al. in Ultrafast and Direct Imprint of Nanostructures in Silicon, Nature, Col. 417, pp. 835-837, June 2002. 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.
Number | Name | Date | Kind |
---|---|---|---|
3783520 | King | Jan 1974 | A |
4070116 | Frosch et al. | Jan 1978 | A |
4119688 | Hiraoka | Oct 1978 | A |
4201800 | Alcorn et al. | May 1980 | A |
4426247 | Tamamura et al. | Jan 1984 | A |
4507331 | Hiraoka | Mar 1985 | A |
4552833 | Ito et al. | Nov 1985 | A |
4600309 | Fay | Jul 1986 | A |
4657845 | Frechet et al. | Apr 1987 | A |
4692205 | Sachdev et al. | Sep 1987 | A |
4707218 | Giammarco et al. | Nov 1987 | A |
4724222 | Feldman | Feb 1988 | A |
4731155 | Napoli et al. | Mar 1988 | A |
4737425 | Lin et al. | Apr 1988 | A |
4808511 | Holmes | Feb 1989 | A |
4826943 | Ito et al. | May 1989 | A |
4848911 | Uchida et al. | Jul 1989 | A |
4857477 | Kanamori | Aug 1989 | A |
4891303 | Garza et al. | Jan 1990 | A |
4908298 | Hefferon et al. | Mar 1990 | A |
4919748 | Bredbenner et al. | Apr 1990 | A |
4921778 | Thackeray et al. | May 1990 | A |
4931351 | McColgin et al. | Jun 1990 | A |
4964945 | Calhoun | Oct 1990 | A |
4976818 | Hashimoto et al. | Dec 1990 | A |
4980316 | Huebner | Dec 1990 | A |
4999280 | Hiraoka | Mar 1991 | A |
5053318 | Gulla et al. | Oct 1991 | A |
5071694 | Uekita et al. | Dec 1991 | A |
5074667 | Miyatake | Dec 1991 | A |
5108875 | Thackeray et al. | Apr 1992 | A |
5148036 | Matsugu et al. | Sep 1992 | A |
5148037 | Suda et al. | Sep 1992 | A |
5151754 | Ishibashi et al. | Sep 1992 | A |
5169494 | Hashimoto et al. | Dec 1992 | A |
5173393 | Sezi et al. | Dec 1992 | A |
5179863 | Uchida et al. | Jan 1993 | A |
5198326 | Hashimoto et al. | Mar 1993 | A |
5212147 | Sheats | May 1993 | A |
5234793 | Sebald et al. | Aug 1993 | A |
5240878 | Fitzsimmons et al. | Aug 1993 | A |
5242711 | DeNatale et al. | Sep 1993 | A |
5244818 | Jokerst et al. | Sep 1993 | A |
5314772 | Kozicki et al. | May 1994 | A |
5318870 | Hartney | Jun 1994 | A |
5324683 | Fitch et al. | Jun 1994 | A |
5328810 | Lowrey et al. | Jul 1994 | A |
5330881 | Sidman et al. | Jul 1994 | A |
5362606 | Hartney et al. | Nov 1994 | A |
5366851 | Novembre | Nov 1994 | A |
5374454 | Bickford et al. | Dec 1994 | A |
5376810 | Hoenk et al. | Dec 1994 | A |
5380474 | Rye et al. | Jan 1995 | A |
5417802 | Obeng | May 1995 | A |
5421981 | Leader et al. | Jun 1995 | A |
5422295 | Choi et al. | Jun 1995 | A |
5424549 | Feldman | Jun 1995 | A |
5425848 | Haisma et al. | Jun 1995 | A |
5431777 | Austin et al. | Jul 1995 | A |
5439766 | Day et al. | Aug 1995 | A |
5453157 | Jeng | Sep 1995 | A |
5458520 | DeMercurio et al. | Oct 1995 | A |
5468542 | Crouch | Nov 1995 | A |
5515167 | Ledger et al. | May 1996 | A |
5527662 | Hashimoto et al. | Jun 1996 | A |
5654238 | Cronin et al. | Aug 1997 | A |
5669303 | Maracas et al. | Sep 1997 | A |
5670415 | Rust | Sep 1997 | A |
5700626 | Lee et al. | Dec 1997 | A |
5736424 | Prybyla et al. | Apr 1998 | A |
5743998 | Park | Apr 1998 | A |
5772905 | Chou | Jun 1998 | A |
5855686 | Rust | Jan 1999 | A |
5895263 | Carter et al. | Apr 1999 | A |
5900160 | Whitesides et al. | May 1999 | A |
5907782 | Wu | May 1999 | A |
5926690 | Toprac et al. | Jul 1999 | A |
5948219 | Rohner | Sep 1999 | A |
5948470 | Harrison et al. | Sep 1999 | A |
5948570 | Kornblit et al. | Sep 1999 | A |
6033977 | Gutsche et al. | Mar 2000 | A |
6035805 | Rust | Mar 2000 | A |
6039897 | Lochhead et al. | Mar 2000 | A |
6096655 | Lee et al. | Aug 2000 | A |
6137562 | Masuyuki et al. | Oct 2000 | A |
6150231 | Muller et al. | Nov 2000 | A |
6150680 | Eastman et al. | Nov 2000 | A |
6245581 | Bonser et al. | Jun 2001 | B1 |
6274294 | Hines | Aug 2001 | B1 |
6309580 | Chou | Oct 2001 | B1 |
6326627 | Putvinski et al. | Dec 2001 | B1 |
6329256 | Ibok | Dec 2001 | B1 |
6334960 | Willson et al. | Jan 2002 | B1 |
6383928 | Eissa | May 2002 | B1 |
6387783 | Furukawa et al. | May 2002 | B1 |
6388253 | Su | May 2002 | B1 |
6391798 | DeFelice et al. | May 2002 | B1 |
6455411 | Jiang et al. | Sep 2002 | B1 |
6482742 | Chou | Nov 2002 | B1 |
6489068 | Kye | Dec 2002 | B1 |
6514672 | Young et al. | Feb 2003 | B1 |
6518168 | Clem et al. | Feb 2003 | B1 |
6534418 | Plat et al. | Mar 2003 | B1 |
6541360 | Plat et al. | Apr 2003 | B1 |
6561706 | Singh et al. | May 2003 | B1 |
6565928 | Sakamoto et al. | May 2003 | B1 |
6632742 | Yang et al. | Oct 2003 | B1 |
6635581 | Wong | Oct 2003 | B1 |
6646662 | Nebashi et al. | Nov 2003 | B1 |
6677252 | Marsh | Jan 2004 | B1 |
6696220 | Bailey et al. | Feb 2004 | B1 |
6703190 | Elian et al. | Mar 2004 | B1 |
6716767 | Shih et al. | Apr 2004 | B1 |
6730256 | Bloomstein et al. | May 2004 | B1 |
6737202 | Gehoski et al. | May 2004 | B1 |
6743713 | Mukherjee-Roy et al. | Jun 2004 | B1 |
6767983 | Fujiyama et al. | Jul 2004 | B1 |
6770852 | Steger | Aug 2004 | B1 |
6776094 | Whitesides et al. | Aug 2004 | B1 |
6777170 | Bloomstein et al. | Aug 2004 | B1 |
20020093122 | Chio et al. | Jul 2002 | A1 |
20020094496 | Stepanian et al. | Jul 2002 | A1 |
20020098426 | Sreenivasan et al. | Jul 2002 | A1 |
20020132482 | Chou | Sep 2002 | A1 |
20020167117 | Chou | Nov 2002 | A1 |
20030080471 | Chou | May 2003 | A1 |
20030081193 | White et al. | May 2003 | A1 |
20030092261 | Kondo et al. | May 2003 | A1 |
20030113638 | Mancini et al. | Jun 2003 | A1 |
20030129542 | Shih et al. | Jul 2003 | A1 |
20030179354 | Araki et al. | Sep 2003 | A1 |
20040029041 | Shih et al. | Feb 2004 | A1 |
20040036201 | Chou et al. | Feb 2004 | A1 |
20040192041 | Jeong et al. | Sep 2004 | A1 |
Number | Date | Country |
---|---|---|
2800476 | Jul 1978 | DE |
55-88332 | Dec 1978 | JP |
57-7931 | Jun 1980 | JP |
63-138730 | Dec 1986 | JP |
1-196749 | Aug 1989 | JP |
02-24848 | Jan 1990 | JP |
02-92603 | Apr 1990 | JP |
WO 0021689 | Apr 2000 | WO |
WO 0147003 | Jun 2001 | WO |
WO 0169317 | Sep 2001 | WO |
WO 0179592 | Oct 2001 | WO |
WO 0179933 | Oct 2001 | WO |
WO 0190816 | Nov 2001 | WO |
Number | Date | Country | |
---|---|---|---|
20040090611 A1 | May 2004 | US |