Source: http://www.google.com/patents/US20040005444?dq=7125605
Timestamp: 2015-02-28 06:33:32
Document Index: 21072760

Matched Legal Cases: ['art 7', 'art 7', 'art 61', 'art 63', 'arts 61', 'art 63', 'art 61', 'art 63', 'art 63', 'art 61']

Patent US20040005444 - Substrate for and a process in connection with the product of structures - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsThe invention relates to a substrate (1) comprising at least a first (2) and a second (8) coating layer on one surface of the substrate, for nanoimprint lithography, said first coating layer (2) consisting of a positive resist and said second (8) coating layer consisting of a negative resist. The invention...http://www.google.com/patents/US20040005444?utm_source=gb-gplus-sharePatent US20040005444 - Substrate for and a process in connection with the product of structuresAdvanced Patent SearchPublication numberUS20040005444 A1Publication typeApplicationApplication numberUS 10/258,027Publication dateJan 8, 2004Filing dateApr 10, 2001Priority dateApr 18, 2000Also published asCN1215528C, CN1437715A, EP1275031A1, US7041228, WO2001079933A1Publication number10258027, 258027, US 2004/0005444 A1, US 2004/005444 A1, US 20040005444 A1, US 20040005444A1, US 2004005444 A1, US 2004005444A1, US-A1-20040005444, US-A1-2004005444, US2004/0005444A1, US2004/005444A1, US20040005444 A1, US20040005444A1, US2004005444 A1, US2004005444A1InventorsBabak HeidariOriginal AssigneeBabak HeidariExport CitationBiBTeX, EndNote, RefManReferenced by (35), Classifications (15), Legal Events (3) External Links: USPTO, USPTO Assignment, EspacenetSubstrate for and a process in connection with the product of structures
[0041] According to the above problem description, it is important for an undercut profile to be produced in the coating layer/layers on the substrate. FIG. 1a shows a substrate that has been coated with a coating layer 2 (a resist) according to the prior art. A pattern of nanometre size has been obtained in the resist 2 by means of NIL, a nanometre-size impression 3 in the resist 2 being shown symbolically in the drawing. The template (not shown) can only produce straight (i.e. vertical) walls in the impression 3, or slightly inclined walls 4, in the best case in this regard. In the bottom of the impression 3, a thin layer of resist 5 remains. FIG. 1b shows the substrate after this thin remaining layer of resist 5 has been removed (developed) in the impression, e.g. by means of plasma etching, so that the substrate 1 has been exposed in the impression 3. The resist thickness has also otherwise been reduced in connection with the removal of the remaining layer 5 in the impression 3, and the walls 4 have possibly become even more inclined and somewhat rounded at the top. [0042] When a metallizing layer 6, e.g. of chromium, is vaporized onto remaining parts of the resist 2 and the exposed part 7 of the substrate 1 in the impression 3, it will settle the whole way over the exposed part 7 of the substrate, over the inclined walls 4 and also over the remaining parts of the resist. This causes problems for a subsequent �lift-off� process, i.e. a process in which the resist is dissolved in a developing bath (e.g. of acetone) so that the parts of the metallizing layer 6 that lie above remaining parts of the resist come loose and fall off. The aim of the lift-off process is that metal 6 shall only remain in the positions 7 where the metal lies directly on the substrate. If the metallizing layer 6 lies over the walls 4, the developing bath cannot reach the resist 2 to dissolve same, however, in which case the lift-off process is made considerably more difficult or becomes impossible. [0043]FIG. 2 shows a problem that can occur with a substrate 1 that has been coated with a lower resist 2, which consists of a positive resist, and a metal layer 9 lying on top of this in which a hole after an impression (not shown) has been etched out. If the positive resist is not exposed to radiation and an isotropic developing method, such as plasma etching, is used, developing proceeds very slowly (e.g. 0.1-2 nm/s) and the result is an unfavourable profile with strongly hollowed-out walls in the positive resist. Here also there is thus a risk that the metal, on subsequent metallization, settles up on the walls of the resist 2, the metal on the actual substrate 1 also risking coming loose in the lift-off process. [0044]FIG. 3 shows a coated substrate according to the invention, the construction of which will be described in greater detail below. The coating layers (resist) 2, 8 have been provided by means of the process according to the invention with an impression 3 with a favourable undercut profile. The walls 4 in the impression here have a profile that is narrower at the upper surface of the uppermost coating layer 8 and wider at the contact with the substrate 1. When the metallizing layer 6 is put on, it will not therefore settle on the walls 4, but only on top of remaining parts of the resist 8 and on the exposed surface 7 of the substrate. Due to this, the walls 4 are advantageously exposed for the encroachment of the developing liquid in a subsequent lift-off stage. [0045]FIG. 4a shows an example of a coated substrate 1 according to a first, preferred embodiment of the invention. This substrate 1 has a first coating layer 2, which is arranged in direct contact with one surface of the substrate and has a layer thickness of around 60-100 nm. The first coating layer 2 consists of a positive photoresist, e.g. Shipley 1800. On application of the first coating layer 2, the resist material has been diluted using a thinner and spun onto the substrate at 6000 rpm for 30 seconds. Following this, the substrate 1 with the layer 2 has been heat-treated (baked) at 110� C. for one minute. [0046] The first coating layer forms a protection for the substrate and a lift-off layer, but is however too thin to form a planarising layer for the substrate. According to a preferred embodiment of the invention, no actual planarising layer is required either, since a device (FIG. 7) and a method are preferably used for the imprint stage that mean that even imprinting can be obtained even on a substrate that is not entirely flat. [0047] Arranged in direct contact with the first coating layer 2 is an intermediate layer 9 of a semiconductor material or a metal, e.g. SiO2, aluminium or chromium, which has a layer thickness of around 20 nm. This intermediate layer 9 consists in the example of an aluminium layer that has been applied by means of vaporization under negative pressure (e.g. 10−6 mbar). [0048] Arranged on top, in direct contact with the intermediate layer 9, is a second coating layer 8, which has a layer thickness of around 50-200 nm, it being true at the same time that the layer thickness for the second layer 8 is greater than the layer thickness for the first layer 2. The second coating layer 8 consists of a negative photoresist, e.g. SC100. On application of the second coating layer 8, the resist material has been diluted using a thinner and spun onto the substrate at 6000 rpm for 30 seconds. The substrate 1 with the layers 2 and 8 has then been heat-treated (baked) at 110-140� C. for one minute. [0049] In certain cases (not shown) a non-stick layer, e.g. of PPM can be arranged on the second layer 8, which non-stick layer is applied by being spun on at 6000 rpm for 30 seconds to a thickness of 10-30 nm. The non-stick layer has lower adhesion to the template (detail no. 610 in FIG. 7) than to the second layer 8. [0050]FIG. 4b shows the coated substrate following nanoimprinting at an imprint temperature below 100� C., e.g. 70� C., and a pressure of around 10-100 bar, in the second coating layer 8 (the negatives resist) and after a thin remaining layer of negative resist in the impression 3 has been removed by means of plasma etching for 10-20 seconds. The intermediate layer 9 here forms the mask for the first coating layer 2 (the positive resist). The first coating layer 2 has a higher glass transition temperature (Tg=85� C.) than the second coating layer 8 (Tg=35-55� C.), meaning that only the second coating layer is in a molten state in the nanoimprint stage, but not the first. [0051]FIG. 4c shows the substrate following removal (etching) of the intermediate layer 9 at a part thereof that was exposed in the impression 3. Since the intermediate layer 9 consists of an aluminium layer, it is best etched away using a liquid that contains HNO3, CH3OOH, H3PO4 and water. FIG. 4d illustrates how the part of the positive resist 2 now exposed in the impression is exposed using UV radiation with a wavelength of 365 nm for 10-30 seconds. The negative resist 8 is naturally also irradiated at the same time. Due to this, cross-links are formed in the negative resist 8, meaning that this cannot be developed away in a selected, subsequent developing stage. The positive resist 2 is not cross-linked, however, but can be developed away in the parts thereof that are exposed to radiation, FIG. 4e. An isotropic developing method is selected here as the developing method, e.g. a developing bath comprising sodium hydroxide or tetramethyl ammonium hydroxide, which is allowed to act for up to 30 seconds. Alternatively, chemical gas etching or plasma etching in oxygen gas, which is allowed to act for around 1.5 minutes, are used. Development of the positive resist 2 takes place here both in a vertical (axial) direction and a horizontal (radial) direction, the undercut profile aspired to according to the invention being created in the coating layers, which is evident in principle from FIG. 4e. Surprisingly, it has turned out to be the case that a positive resist exposed using radiation is etched much more quickly in a plasma etching stage or chemical gas etching stage than a non-exposed positive resist is, e.g. 2-10 nm/s compared with 0.1-2 nm/s. An undercut but not too �hollowed-out� profile can thus advantageously be created in the positive resist. [0052]FIG. 5a shows a coated substrate 1 according to a second embodiment of the invention. This substrate 1 has a first coating layer 2, which consists of a positive resist, e.g. PMMA or ZEP, which is arranged in direct contact with one surface of the substrate and has a layer thickness of around 80 nm. Arranged on top of the first coating layer 2, in direct contact with the same, is a second coating layer 8, which consists of a negative resist, e.g. SC100 or SAL, and which has a layer thickness of around 80 nm. [0053]FIG. 5b shows the coated substrate following nanoimprinting at 85� C. of the second coating layer 8 (the negative resist). Here also, the first coating layer 2 has a higher glass transition temperature (Tg=110-117� C.) than the second coating layer 8 (Tg=35-55� C.). Cross-linking is also achieved in the material for the second coating layer 8 at the nanoimprint temperature, meaning that this will be developed more slowly than the first coating layer 2 in a subsequent developing stage. [0054]FIG. 5c shows how an undercut profile is obtained by means of isotropic plasma etching at 5.5 mbar. Thanks to the different material properties of the first and second coating layer respectively, which property differences are accentuated by the heat-induced cross-linking in the second layer 8, the developing rate for the first layer 2 will be higher than for the second layer 8 (1.5 nm/s compared with 1 nm/s). It must also be noted that in this embodiment, removal of the thin layer of the second coating layer 8 remaining in the impression 3 following imprinting is executed in the same stage as development of the first layer 2. [0055]FIG. 6a shows a coated substrate 1 according to a third embodiment of the invention. This substrate 1 has a first coating layer 2, which consists of a positive resist, e.g. PMMA or ZEP, which is arranged in direct contact with one surface of the substrate and has a layer thickness of around 200 nm. Arranged in direct contact with the first coating layer 2 is an intermediate layer 9 (a mask) of a semiconductor material or a metal, e.g. SiO2, aluminiun or chromium, which has a layer thickness of around 20 nm. Arranged on top, in direct contact with the intermediate layer 9, is a second coating layer 8, which has a layer thickness of around 30-40 nm. The second coating layer 8 consists of a negative resist, e.g. SC100 or SAL. [0056]FIG. 6b shows the coated substrate following nanoimprinting at 85� C. of the second coating layer 8 (the negative resist). Here also he first coating layer 2 has a higher glass transition temperature (Tg=110-117� C.) than the second coating layer 8 (Tg=35-55� C.). Cross-linking is also achieved in the material for the second coating layer 8 at the nanoimprint temperature. [0057]FIG. 6c shows the substrate following removal (etching) of the intermediate layer 9 at its part exposed in the impression 3. FIG. 6d shows the result following isotropic developing, plasma etching, of the positive resist 2 at its part exposed in the impression 3. As in the embodiment according to FIGS. 5a-c, the developing rate for a selected isotropic method, e.g. a wet method, is higher for the first coating layer than for the second coating layer, which leads to the desired undercut profile. [0058]FIG. 7 shows a device according to SE-AO-9904517-1 for the actual imprint stage in the process according to the invention, which device is specially adapted for NIL of relatively large substrates without these needing to be provided with planarising layers. Detail number 61 in FIG. 7 represents a first main part in a preferred embodiment of such a device. This first main part 61 comprises a first principally flat base plate 62, which is preferably disposed to be displaced in a direction that coincides with the normal for its surface 62 a facing a second main part 63. A principally flat bearing plate 64, on which bearing plate the coated substrate 1 is intended to be placed, can be affixed to this surface 62 a. Alternatively, the substrate 1 can be placed directly onto the surface 62 a. The substrate 1 is preferably circular. The main parts 61 and 63 preferably also have a rotationally symmetrical appearance. [0059] The second main part 63 has a cavity 66, which is formed by a bottom 67 and, in the example shown, circular-cylindrical side walls 68. As a roof for the cavity 66, a flat, flexible membrane 69 is arranged opposite the bottom 67. This membrane 69 consists of a polymer material or a thin metal, preferably plastic, rubber or thin metal. One side 69 a of the membrane forms a support for the template 610, and has a diameter or maximum width of 25-400 mm, preferably 50-350 mm. The membrane has a thickness of up to 10 mm, preferably up to 3 mm and even more preferredly up to 1 mm. The template 610 consists, according to the known technique for nanoimprint lithography, of a plate of e.g. metal, which is provided with a fine structural pattern, with dimensions of nanometre size, on its surface 610 a facing towards the first main part 61. [0060] The membrane 610 is fixed on the second main part 63, around the periphery of the membrane 69 at edges of the cavity 66, by means of a fixing device. A ring 611, which is circular in the example shown, is used as the fixing device, which ring is disposed to press firmly the peripheral edges of the membrane 69 between itself and the free edges of the side walls 68. Along its inner circular edge, on the side thereof that faces towards the membrane, the ring 611 is preferably bevelled 611 a, to provide a soft deflection for the membrane 69 on the transition from the ring 611. The risk is hereby reduced of splits or fold notches in the membrane 69, its life being extended. [0061] The cavity 66 is intended to accommodate a medium, which consists of a gas or liquid of low compressibility, preferably oil and even more preferredly hydraulic oil, which can be pressurized via an inlet channel 612, which can be disposed in the side walls 68 or in the bottom 67 of the cavity. Pressurization takes place by means of a pump (not shown), which is best adapted to provide a pressure with very small variations. This can be achieved e.g. by means of a proportional valve. Contained in the second main part 63 is also a second principally flat base plate 613, which forms a support for the part with the cavity 66. [0062] At the imprint stage, the substrate 1 (including the coating layer, not shown) is heated, following which a pressure is applied in the cavity, e.g. around 5-500 bar, so that the membrane 69 flexes out The surface 610 a of the template and the coated surface 1 a of the substrate are thereby pressed together, against the first main part 61. [0063]FIG. 8a, with reference numbers according to FIG. 8b, shows a substrate that has been coated, imprinted and developed according to the invention. In the scanning electron microscope image in FIG. 8a, the transition between the different coating layers 2, 8 is not visible, nor is the transition between the actual substrate 1 and the resist 2. These transitions have been drawn in using dashed lines in FIG. 8b. FIGS. 8a-b are also shown in cross-section and slightly in perspective, which has been achieved by breaking the substrate off at a hole in the same and then inclining it just a little when the SEM image was taken. It is the view in perspective and the fact that the break is not entirely clean that leads to the uneven edges between the resist 2 and detail 2′. The latter probably consists of resist residues by the break. Above the upper resist 8, an edge 10 is visible of a hole that lies further-away in the view. It is plainly evident that the desired undercut profile 4 has been achieved by means of the invention. Cf. also FIG. 3. EXAMPLE 1 [0064]FIGS. 9a-d show a substrate that has been coated, imprinted and developed. Following developing, metallizing has been carried out, followed by lift-off. The illustrations thus show the resulting metal coating on the substrate. FIGS. 9a-b show here a substrate according to the prior art, with only one layer of resist, while FIGS. 9c-d show a substrate constructed according to the specification, FIG. 4a-e. The first coating layer consisted of 70 nm of Shipley 1800, the intermediate layer 9 consisted of 20 nm of aluminium, and the second layer 8 consisted of 130 nm of SC100. The irradiation used consisted of UV radiation with a wavelength of 265 nm for a time of 20 seconds. Developing was carried out in a bath of sodium hydroxide. As is visible in a comparison of FIGS. 9a and 9 c, and 9 b and 9 d, the improvement in the result is considerable when the invention is used. The metal structure in FIGS. 9a and 9 b has a number of voids and uneven edges, while the metal structure in FIGS. 9c and d is complete and with even edges. Another difference consisted in the fact that the lift-off process in FIGS. 9a-b took around 10 minutes in a bath during ultrasonic treatment, while the lift-off process in FIGS. 9c-d took only around 30-50 seconds in a corresponding bath. In FIGS. 9b and 9 d, dimensions are indicated by a white line that corresponds to 100 nm in length. EXAMPLE 2 [0065] Table 1 exemplifies how different resist types can be selected for the different embodiments according to FIGS. 4-6, suitable imprint temperatures also being evident. It can also be noted in this connection that the temperature is reduced to around 25� C. before the template is removed from the coated substrate. TABLE 1 Second layer: SC100 SAL 40� C. 55� C. First layer: Shipley 1800 A A 85� C.**) (60-85� C.)*) (75-85� C.) PMMA B, C B, C 117� C. (60-117� C.) (75-117� C.) ZEP B, C B, C 110� C. (60-110� C.) (75-110� C.) [0066] The invention is not restricted to the embodiments shown above, but can be varied within the scope of the claims. Referenced byCiting PatentFiling datePublication dateApplicantTitleUS7354698Jan 7, 2005Apr 8, 2008Asml Netherlands B.V.Imprint lithographyUS7377764Jun 13, 2005May 27, 2008Asml Netherlands B.V.Imprint lithographyUS7418902May 31, 2005Sep 2, 2008Asml Netherlands B.V.Imprint lithography including alignmentUS7442029May 16, 2005Oct 28, 2008Asml Netherlands B.V.Imprint lithographyUS7490547Dec 30, 2004Feb 17, 2009Asml Netherlands B.V.Imprint lithographyUS7517211Dec 21, 2005Apr 14, 2009Asml Netherlands B.V.Imprint lithographyUS7523701Mar 7, 2005Apr 28, 2009Asml Netherlands B.V.Imprint lithography method and apparatusUS7611348Apr 19, 2005Nov 3, 2009Asml Netherlands B.V.Imprint lithographyUS7618250May 25, 2006Nov 17, 2009Asml Netherlands B.V.Imprint lithographyUS7636475Dec 16, 2005Dec 22, 2009Asml Netherlands B.V.Imprint lithographyUS7648641Jun 17, 2005Jan 19, 2010Hitachi Global Storage Technologies Netherlands B.V.Method and apparatus for creating a topographically patterned substrateUS7676088Dec 23, 2004Mar 9, 2010Asml Netherlands B.V.Imprint lithographyUS7686970Dec 30, 2004Mar 30, 2010Asml Netherlands B.V.Imprint lithographyUS7692771May 27, 2005Apr 6, 2010Asml Netherlands B.V.Imprint lithographyUS7698999Mar 1, 2005Apr 20, 2010Asml Netherlands B.V.Printing apparatus and device manufacturing methodUS7708924Jul 21, 2005May 4, 2010Asml Netherlands B.V.Imprint lithographyUS7730834Mar 4, 2004Jun 8, 2010Asml Netherlands B.V.Printing apparatus and device manufacturing methodUS7762186Apr 19, 2005Jul 27, 2010Asml Netherlands B.V.Imprint lithographyUS7854877Aug 14, 2007Dec 21, 2010Asml Netherlands B.V.Lithography meandering orderUS7878791Mar 1, 2006Feb 1, 2011Asml Netherlands B.V.Imprint lithographyUS7906059Mar 16, 2009Mar 15, 2011Asml Netherlands B.V.Imprint lithographyUS7922474Feb 17, 2005Apr 12, 2011Asml Netherlands B.V.Imprint lithographyUS7931844Sep 23, 2008Apr 26, 2011Asml Netherlands B.V.Imprint lithographyUS8011915Mar 1, 2006Sep 6, 2011Asml Netherlands B.V.Imprint lithographyUS8015939Jun 30, 2006Sep 13, 2011Asml Netherlands B.V.Imprintable medium dispenserUS8100684Feb 24, 2009Jan 24, 2012Asml Netherlands B.V.Imprint lithographyUS8131078Nov 10, 2009Mar 6, 2012Asml Netherlands B.V.Imprint lithographyUS8144309Sep 5, 2007Mar 27, 2012Asml Netherlands B.V.Imprint lithographyUS8241550Oct 6, 2009Aug 14, 2012Asml Netherlands B.V.Imprint lithographyUS8318253Jun 30, 2006Nov 27, 2012Asml Netherlands B.V.Imprint lithographyUS8323541Feb 22, 2012Dec 4, 2012Asml Netherlands B.V.Imprint lithographyUS8349238Jun 17, 2010Jan 8, 2013Asml Netherlands B.V.Imprint lithographyUS8486485Jul 29, 2011Jul 16, 2013Asml Netherlands B.V.Method of dispensing imprintable mediumUS8571318Feb 8, 2012Oct 29, 2013Asml Netherlands B.V.Imprint lithographyUS8753557Dec 20, 2011Jun 17, 2014Asml Netherlands B.V.Imprint lithographyClassifications U.S. Classification428/212, 216/41, 257/E21.034International ClassificationH01L21/027, B82B1/00, G03F7/20, G03F7/004, G03F7/095, H01L21/033, G03F7/26, B81B1/00Cooperative ClassificationG03F7/095, H01L21/0331European ClassificationG03F7/095, H01L21/033BLegal EventsDateCodeEventDescriptionOct 21, 2013FPAYFee paymentYear of fee payment: 8Oct 24, 2009FPAYFee paymentYear of fee payment: 4Jan 21, 2003ASAssignmentOwner name: OBDUCAT AKTIEBOLAG, SWEDENFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:HEIDARI, BATAK;REEL/FRAME:013683/0752Effective date: 20021016RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services