DE10325459A1 - Creating a high-resolution structure with a substance that can be altered with an optical signal comprises applying the signal so that an intensity minimum excludes a restricted area, e.g. for writing to data storage media - Google Patents

Abstract

Creation of a permanent structure with high spatial resolution comprises providing a substance that can be altered with an optical signal in a writing zone and applying the optical signal so that a local intensity minimum excludes a spatially restricted area of the writing zone from being altered while alteration of the rest of the writing zone reaches saturation. An independent claim is also included for a device with a permanently structurable writing zone comprising a substance that can be altered with an optical signal, where the substance can be repeatedly converted from a state A to a state B, each with different optical properties, and converted back from state B to state A, but only in state A can the substance be permanently changed to another state C with a writing signal.

Description

The The invention relates to a method for spatially high-resolution generation a permanent structure using an optical signal with the features of the preamble of claim 1. Furthermore The invention relates to a device using one of an optical signal permanently structurable writing area according to the preamble of claim 24. The invention can especially when writing to an optical data memory and find application in the formation of microlithographic structures.

The Durability of those generated with the method or with the device Structure should at least for a period much larger than 1 minute and preferably for a period much larger than 1 Day or even more preferred until the desired change or deletion of the Structure be given, so that the generated structure with a larger temporal Distance to their generation is usable.

at a known method according to the preamble of claim 1, in which a device according to the preamble of claim 24 is used there will be a layer of photoresist with the optical signal everywhere there exposed where it changed permanently shall be. The desired structure does not consist of the changed Partial areas of the writing area but from those with the optical Signal deliberately omitted partial areas.

The spatial resolution both imaging and modifying optical processes basically through by the wavelength dependent on the light used Diffraction limit (Abbe'sche Limit).

So is the diffraction limit for all known methods for spatially high-resolution generation a permanent structure using an optical signal The natural Lower limit for the resolution for example when writing data to an optical data memory and therefore for the data density achievable in the data memory or in microlithography. To create ever smaller structures, e.g. B. in a photoresist So far, one has been forced to switch to shorter and shorter wavelengths. Therefore, far-reaching UV light (deep UV) is currently used light), for the The future will be the use of X-ray light. On The problem is that light with a wavelength <250 nm is difficult to focus and the optics to be used become expensive and inefficient.

On Methods are already known in the field of fluorescence microscopy where by using nonlinear relationships between the sharpness of the effective focal spot and the irradiated intensity the diffraction limit when mapping a structure of a sample becomes. Examples are multiphoton absorption in the sample or the generation of higher harmonics of the incident light. Also a saturation of an optically induced transition can be used as a nonlinear relationship, such as with depopulation of the fluorescent state through stimulated emission stimulated emission depletion = STED) or depopulation the ground state depletion (GSD). at these two processes, which in principle achieve molecular resolutions can, becomes a fluorescent dye with which the structure of interest a sample is marked, everywhere where an optical signal has a characteristic limit, i.e. exceeds a saturation limit, placed in an energy state from which no fluorescence (more) he follows. If the spatial Area from which a measurement signal is then registered by a local intensity minimum of the optical signal is determined, which has a zero and generated by interference, for example, are its dimensions and thus the spatial resolution achieved smaller than the diffraction limit. The reason is that the spatial limited sub-area from which the measurement signal is registered, with increasing degree of saturation depopulation of the state involved in fluorescence is concentrated. Exactly the same the edge of a focal spot or strip steeper, which is also to an elevated spatial resolution leads.

On concrete STED method is known from WO 95/21393 A1. at a sample or a fluorescent dye in this method the sample is stimulated to fluorescence by an optical excitation signal. The spatial Part of the suggestion for which is normally the diffraction limit is then reduced, by having an intensity minimum an interference pattern of an optical de-excitation signal is superimposed becomes. Everywhere over there, where the de-excitation signal exceeds a saturation limit the fluorescent dye is at least essentially completely through stimulated emission switched off, i.e. from the previously suggested Energy state again depleted. The remaining spatial Subarea from which subsequently fluorescent light is still emitted spontaneously, only corresponds a reduced area around the zero of the intensity minimum, in which the de-excitation signal was not present or was not present with sufficient intensity.

From The Journal of Biological Chemistry, Vol. 275, No. 84, pages 25879-25882 (2000), a protein is known which is increasingly stimulable to fluorescence in the red region by green light, but which loses its fluorescence properties when irradiated with blue light. This process is reversible. Apparently, the green light switches the protein into a conformational state in which it has the fluorescent property and at the same time stimulates fluorescence, while the blue light switches the protein into a conformational state without the fluorescent properties. The protein is a natural protein found in the sea anemone Anemonia sulcata, whose functions described here can be enhanced by the targeted exchange of an amino acid.

Farther it is from the magazine Nature Vol. 388, pages 355-358, (1997) known to be the green fluorescent protein (English: green-fluorescent protein, GFP) and mutants thereof between two states can be switched one being spectrally different from the other. Both Proteins can can be used as fluorescent markers in living cells.

Out of the publication Nature, Vol. 420, pages 759-760, (2002) are fluorescent molecules known from the family of diarylethenes, who are between one fluorescent and a non-fluorescent state any toggle back and forth. Both states are thermally stable, so the switching process, which is photoisomerization or photocyclization, with comparatively low intensities optical signal can be forced. Molecules under the influence of light change their color, are generally referred to as photochromic molecules.

The The invention has for its object a method according to the preamble of claim 1 to show, in which the diffraction limit at Create permanent structures using an optical one Signal is below. Furthermore, one for such Method suitable device according to the preamble of the claim 24 are shown.

SUMMARY THE INVENTION

The The object of the invention is achieved by a method with the features of claim 1 and a device with the features of Claim 24 solved.

advantageous embodiments of the method and the device are described in the dependent claims, being the subclaims 22 and 23 concern specific applications of the new method and with further advantageous embodiments of the new device also from the dependent ones claims to be deduced to the procedure.

DESCRIPTION THE INVENTION

at The new method is the one specifically omitted from the optical signal Subarea in which no or at least essentially no change of the substance, a local intensity minimum of the optical signal. At the same time, the optical signal is deliberately left out spatial limited portion so that when changing the Substance with the optical part of the saturation is reached. As a result are the dimensions of the section in which the substance passes through the optical signal does not change is smaller than the diffraction limit.

The local intensity minimum of the optical signal is in the new method by interference generated. The term interference is very broad. In this way, two or more light beams are not necessarily superimposed on one another. For example can also the interference effects that occur when focusing a light beam be used.

The saturation when changing the substance with the optical signal is achieved by the optical Signal outside the deliberately omitted spatial limited sub-range with an intensity above a saturation limit is applied, from which the substance is completely or at least essentially completely changed becomes. It is understood that to fall below the diffraction limit the saturation limit not only at the location of the intensity maxima is reached, the intensity minimum in the limited space Subarea are adjacent. Rather, the saturation limit must also be closer to the local one intensity minimum be crossed lying down, to effectively fall below the diffraction limit. This is through an increase the intensity of the optical signal.

The new method can be used to create one-, two- or even three-dimensional structures in the writing area. It goes without saying that the writing area must be designed in accordance with the desired dimensionality of the structure and be provided with the substance. The substance is preferably homogeneously distributed in the writing area or systematically arranged in order to ensure constant conditions over the entire area To worry about writing area.

Around to fully form the structure in the writing area, it is provided that the writing area is targeted with that of the optical signal omitted partial area is scanned. Because the structure too at several spaced apart points, i.e. several spatially limited Subareas that can be generated at the same time can be the writing area also with several specifically omitted from the optical signal Partial areas are scanned simultaneously. So the time is required for the Generation of the respective structure reduced.

There each partial area specifically omitted from the optical signal local intensity minimum of an interference pattern, the scanning can be carried out by shifting a or more interference minima of the optical signal. This shift can be caused by a phase shift of the interfering Rays are caused.

at With the new method, the optical signal can directly be the write signal with which the desired one Structure is created. This is the substance from the group of To select substances that with the optical signal permanently from an initial state in a changed one State changeable are. The areas specifically omitted from the optical signal are then the desired structure with a spatial resolution below the diffraction limit. Falling below the diffraction limit is not only achieved if the structure created has dimensions below the diffraction limit, but also when the transitions to the Structure sharper than specified by the diffraction limit. Specifically, at the embodiment of the new process, in which the optical signal directly as a write signal serves to write data points into an optical memory, which is characterized by special sharpness and feature small dimensions while their distance continues is defined by the diffraction limit.

at a second basic one embodiment The distance between such data points can also be changed using the new method the diffraction limit. For this, the substance from the Group of substances selected those with the optical signal repeated from a first state with first properties can be converted into a second state with second properties and which can be brought back from the second state to the first state are, the substance only in the first state with a write signal is permanently changeable to the other state. That is, here is the optical signal is not yet the write signal, which is additionally applied becomes. Rather, the optical signal is used to move the substance outside to put the deliberately omitted partial area into the state, which is referred to here as the second state and from which none permanent change the substance with the write signal. The only temporary transfer of the Substance with the optical signal from their first state in their second state is in this second embodiment of the new method Prerequisite for this that even with the spacing of the details of the structure created, the diffraction limit can be undercut. The structure is always in one Section changed with the write signal, the smaller dimensions than the diffraction limit. Whether in the area of this area further changes made are not yet determined by this. The first and second Properties of the substance in its first and second states have to not necessarily be "binary", i.e. the changeability the substance with the write signal does not need to be in the first state 100% and 0% in the second state. It is much more sufficient if these properties in relation to the write signal so big Differences show that a clear assignment of the write signal the first state is given, so the substance is essentially is only permanently changed by the write signal in its first state.

In a preferred variant of the second embodiment of the new method is the write signal that additionally is applied to the optical signal, also an optical Signal. In this case, the first and second properties include the substance in its first and second states also different optical properties, with only the first properties the optical Support write signal. The write signal can also be from the invisible area of the electromagnetic spectrum come, for example, from far away Infrared or the microwave range. Likewise, electromagnetic radiation one wavelength smaller than 250 nm can be used as an optical write signal. In each Case remains as an advantage over the state of the art that the write signal does not affect the partial area must be focused on that permanently within the writing area changed should be, because the spatial Definition of the permanently to be changed Subareas are done by the spatial Determination of the second state of the substance using the optical Signal. So the write signal can also be a non-electromagnetic one Signal, for example thermally or chemically.

Substances with two different states with different properties that are suitable for the new method can be selected from the subset of substances, in which the two states with the different properties have different conformational states of a molecule or a group of molecules or different chemical bonds and / or can be converted into one another by photoisomerization or photocyclization. The optical signal can correspondingly a rearrangement of bonds or atom groups, a cis-trans isomerization, a cyclization reaction, a protonation / de-protonation, a spin flip, a change in orientation of molecules or groups of molecules, and / or an electron transfer and / or trigger energy transfer between linked molecules or molecular subunits.

On greater The advantage of the new method is that the two states with the first and second properties of many of the substances in question a much longer one Lifespan as an energy state involved in fluorescence, for example Have dye. In addition, the intensities required to achieve the saturation for example a change in conformation is required relatively low. State changes, where the initial state and / or the final state are relatively long-lived (greater than 100 ns) can with comparatively low intensities of the optical signal become. The more durable the conditions the lower the intensities required.

Prefers are in the second embodiment of the new process substances with a switching signal the second state can be converted into the first state. With the switching signal can then transfer the Target substance with the optical signal in the second state reversed become. The switching signal can be an optical switching signal. It can also be an electrical or thermal signal or a signal from the non-optical part of the electromagnetic Trade spectrum. It is also possible that the substance is spontaneous returns to its first state, i.e. thermally driven at ambient temperature. So it is known that molecules undergoing photo-induced cis-trans isomerization, pure can thermally return to the first state. With a switching signal, that specifically returns the substance to its first state, can usually speed up the process, or at least be better controlled.

Around undesirable Interactions between the different signals in the second embodiment to exclude the new procedure, it is preferred if the permanent change of the substance with the Write signal in the other state neither through the optical signal still undone by the switching signal becomes.

The Switching signal is provided before or if the successful transfer of the Substance in the second state through the optical signal not basically is questioned, along with the optical signal on the Writing area applied.

In particular it is not necessary to switch the switching signal to the sub-areas of the writing area in which the structure is currently is produced. The spatial The new method limits the structure done by the optical signal.

The Write signal used in the second embodiment of the new method also not to be changed Parts of the writing area need to be localized is applied to the sample after or simultaneously with the optical signal. With a simultaneous application it should be noted that no mutual interference may occur.

Even though, as mentioned above, the signals may overlap in time, becomes understanding the second embodiment of the new method when considering the following signal sequences relieved, which repeats itself cyclically. The substance is there themselves in the writing area in their first state. With the optical The substance is signaled in partial areas of the writing area transferred their second state. in this connection is the spatial limited portion omitted by making the substance permanent to be changed should and in which it is still in its first state. The write signal is then used in the partial area Substance permanently changed to its other state. After that, the substance restored to its first state in the writing area. This can be done with the help of the switching signal. Then the cycle starts again from the front at another point in the writing area. At a The optical signal must also be less localized Signal that the substance in its insensitive to the write signal second state transfers the write area cover large areas. With a stronger one localized write signal this is not necessary. Point of time the presence of each signal in the new procedure is determined after reaching certain intensities. So can too periodic modulations of the signals are carried out, to implement the cyclical sequence of the signals.

The substance can be selected from the group of proteins, for example. These include the well-known proteins asCP (asF595) and T70a / A148S / S165V, which have two conformational states with different optical properties, or also the green fluorescent protein (GFP) and mutants derived from it.

The permanent change the substance in the other state can be irreversible or reversible his. If it is reversible, its reversal should not go through the switching signal is still another one of the original change used signals are effected. Rather, repeal of change another signal with different properties may be necessary.

If the other state of the substance in which they are using the new process is permanently transferred for example a changed one optical property from absorption, scattering and polarization comprehensive group or a changed luminescence from fluorescence, phosphorescence, electroluminescence and chemiluminescence comprehensive group, the generated structure of the other Condition can be read out with a test beam.

at Exploiting the opportunities of the present invention, an optical Data storage with particularly high data density are described, which is no longer limited by the diffraction limit. Likewise, micro and Nanostructures with an over the diffraction limit beyond improved resolution become.

The defined in claim 24 new device for performing the second embodiment of the new method can be used and is particularly suitable as an optical data storage.

SUMMARY THE FIGURES

in the The following are the basics of the invention with reference to in the Figures illustrated details further explained and described.

1 symbolically shows two different states of a molecule that can be used as a substance in the second embodiment of the new method.

2 shows an exemplary cyclic sequence of signals in the second embodiment of the new method.

3 shows schematically an arrangement for performing the new method.

DESCRIPTION OF THE FIGURES

1 shows structural formulas and energy states of a molecule that can be in two different states A and B. Out of state A, which is also referred to in the preceding description and in the claims as the first state, the molecule has a write signal 3 permanently changeable to another state not shown here; however, not from state A, which is also referred to in the preceding description and in the claims as the first state. Specifically, the optical write signal transfers 3 the molecule in state A here from an energetic ground state 1 in an energetically excited state 2 , from which it gets permanently into the other state, not shown. The states A and B are two isomers (trans and cis) of a molecule that are photoisomerized by an optical signal 4 from state A to state B and also by an optical switching signal 5 can be converted from state B back into state A. The write signal 3 causes no permanent change in state B for reasons of insufficient photon energy, since the higher energetically excited state here 2 is not reached.

2 shows a preferred cyclic sequence of the signals, that is, the optical signal 4 , of the switching signal 5 and the write signal 3 , In addition to states A and B, the permanently changed state C of the substance under consideration is also shown in sub-figures 2 c) to e). The sequence represented by the sub-figures is: a) The switching signal 4 switches the substance to the writable state A. b) That over at least one local intensity minimum 9 deciding optical signal 5 is on the writing area 7 applies and switches the substance outside the intensity minimum 9 from state A to state B. Due to the saturation of the switching process, the spatial sub-area in which the substance remains in state A is reduced to dimensions that are only dependent on the degree of saturation and the original steepness or width of the intensity minimum. c) The write signal 3 Converts the substance in state A, but not those in state B, permanently to state C. d) The switching signal 4 switches the substance not transferred to state C back to state A. 5) The optical signal 5 is applied again, with the zero 16 of the at least one intensity minimum 9 to another location in the writing area 7 is positioned.

3 shows schematically a possible arrangement for carrying out the invention. Optical rays 10 of the optical signal 5 are through a wavefront deformator 12 deformed so that after passing a dichroic mirror 13 and a lens 14 in the writing area 7 an interference pattern with the zero 16 having intensity minimum 9 form. The optical signal saturates the transition 6 from state A to state B, so that only a subdiffraction region of the substance remains in state A along the reproduced location coordinate X. The write signal 3 that over the dichroic mirror 13 and the lens 4 on the writing area 7 is applied, the substance in state A permanently changes to the other state C.

Claims (25)

Method for spatially high-resolution generation of a permanent structure, a substance that can be changed with an optical signal being provided in a writing area and the optical signal being applied to the writing area in such a way that it deliberately omits a spatially limited partial area in the permanent area a different state of the substance is set than in partial areas of the writing area detected by the optical signal, characterized in that the 5 ) deliberately omitted partial area a local intensity minimum ( 9 ) of the optical signal ( 5 ) and that the optical signal ( 5 ) is applied outside the deliberately omitted, spatially limited partial area in such a way that saturation is achieved when the substance is changed with the optical signal. A method according to claim 1, characterized in that the local intensity minimum ( 9 ) of the optical signal ( 5 ) with a zero ( 16 ) is generated by interference. A method according to claim 1 or 2, characterized in that the optical signal ( 5 ) is applied outside the deliberately omitted, spatially limited sub-area with an intensity above a saturation limit, from which the substance is completely changed by the optical signal. Method according to one of claims 1 to 3, characterized in that by permanently setting a different state of the substance a one-, two- or three-dimensional structure in the writing area ( 7 ) is produced. Method according to one of claims 1 to 4, characterized in that the substance in the writing area ( 7 ) is distributed homogeneously or arranged systematically. Method according to one of claims 1 to 5, characterized in that the writing area ( 7 ) with that of the optical signal ( 5 ) the specifically omitted partial area is scanned. A method according to claim 6, characterized in that the writing area ( 7 ) with several of the optical signal ( 5 ) selectively omitted partial areas are scanned at the same time. Method according to one of claims 1 to 7, characterized in that the substance is selected from the group of substances which with the optical signal ( 5 ) can be permanently changed from an initial state to a changed state. Method according to one of claims 1 to 7, characterized in that the substance is selected from the group of substances which with the optical signal ( 5 ) can be repeatedly transferred from a first state (A) with first properties to a second state (B) with second properties and which can be brought back from the second state (B) to the first state (A), the substance only in the first state (A) with a write signal ( 3 ) is permanently changeable to the other state (C). A method according to claim 9, characterized in that the write signal ( 3 ) an optical write signal ( 3 ) is. A method according to claim 9 or 10, characterized in that that the substance is selected from the subset of substances where the two states (A and B) with different properties different conformational of a molecule or a group of molecules or have different chemical bonds and / or by one Photoisomerization or photocyclization can be converted into one another. Method according to one of claims 9 to 11, characterized in that the substance is selected from the subgroup of substances which with a switching signal ( 4 ) at the second state (B) can be converted into the first state (A). A method according to claim 12, characterized in that the switching signal ( 4 ) an optical switching signal ( 4 ) is. A method according to claim 12 or 13, characterized in that the permanent change of the substance with the write signal ( 3 ) to the other state (c) neither by the optical signal ( 4 ) still by the switching signal ( 5 ) is undone. Method according to one of claims 12 to 14, characterized in that the switching signal ( 4 ) before or at the same time as the optical signal ( 5 ) on the writing area ( 7 ) is applied. Method according to one of claims 12 to 15, characterized in that the switching signal ( 4 ) over the deliberately omitted section and over the optical signal ( 5 ) captured partial areas on the writing area ( 7 ) is applied. Method according to one of claims 9 to 16, characterized in that the write signal ( 3 ) over from the optical signal ( 5 ) captured partial areas and the specifically omitted partial area on the writing area ( 7 ) is applied. Method according to one of claims 9 to 17, characterized in that the write signal ( 3 ) after or simultaneously with the optical signal ( 5 ) on the writing area ( 7 ) is applied. Method according to one of claims 9 to 18, characterized in that that the substance is selected from the group of substances which include proteins. Method according to one of claims 1 to 19, characterized in that that the other state of the substance is a changed optical property from the group comprising absorption, scattering and polarization having. Method according to one of claims 1 to 19, characterized in that that the other state of the substance changes luminescence from the Fluorescence, phosphorescence, electroluminescence and chemiluminescence comprehensive group. Application of a method according to one of claims 1 to 21 for writing into a data memory. Application of a method according to one of claims 1 to 21 for generating micro- or nanolithographic structures. Device with a permanently structurable writing area, in which a substance which can be modified with an optical signal is provided, characterized in that the substance belongs to the group of substances which are associated with the optical signal ( 5 ) can be repeatedly transferred from a first state (A) with first optical properties to a second state (B) with second optical properties and which can be brought back from the second state (B) to the first state (A), the substance only in the first state (A) with a write signal ( 3 ) is permanently changeable to the other state (C). Use of a device according to claim 24 as optical data storage.