Waveguide plate and process for its production and microtitre plate
View Patent ↗A waveguide plate and a process for making the waveguide plate with a plate-like glass substrate ( 1 ), carrying a waveguiding layer ( 2 ), with at least one coupling grating on the surface carrying said waveguiding layer ( 2 ), which coupling grating is formed as a grating of lines with a period between 150 nm and 1000 nm, the extension of said grating being at least 5 cm with lines parallel to one another, wherein the coupling angle ( ) varies by not more than 0.1_/cm along a line of said grating and wherein the absolute value of the deviation of the coupling angle ( ) on said waveguide plate, from a predefined desired value, does not exceed 0.5_. The deviation from the average value of the coupling angle does not exceed 0.3_, preferably not 0.15_ on the whole waveguide plate. The waveguide plate is suitable as part of a sensor platform and of an arrangement of sample compartments for chemo-and bioanalytical investigations in order to produce a coupling grating formed as a line grating with a grating period between 100 nm and 2500 nm
1. A process for producing at least one continuous grating structure formed as a line grating with distances of between 100 nm and 2500 nm between consecutive grating lines on a surface portion of a substrate, by covering the surface portion with a photoresist layer,
bringing the surface portion into proximity of a phase mask having a grating structure, with the photoresist layer facing said mask,
exposing the phase mask at an angle which departs from the Littrow angle (θ L ) or from 0° by no more than 10°,
developing the photoresist layer and subjecting the surface portion to an etch process to produce the grating structure,
removing the photoresist layer,
wherein the phase mask has a transparent region with a diffraction grating and with portions of the diffraction grating masked.
2. The process according to claim 1 , wherein the extension of the at least one grating structure is at least 0.5 cm parallel to the lines.
3. The process according to claim 1 , wherein the surface area of at least one grating structure on the phase mask is at least 10 cm 2 .
4. The process according to claim 1 , wherein the exposure of the photoresist layer is to a mercury-vapour lamp.
5. The process according to claim 1 ,
wherein the exposure of the photoresist layer is to an excimer laser or argon laser.
6. The process according to claim 1 ,
wherein the phase mask comprises a transparent substrate and a layer interrupted in a structured way optically inactivating the grating structure.
7. The process according to claim 6 ,
wherein the interrupted layer consists of a nontransparent material.
8. The process according to claim 7 ,
wherein the substrate is a quartz substrate.
9. The process according to claim 1 ,
wherein the side of the phase mask facing the photoresist layer is covered by an antireflection layer.
10. The process according to claim 1 ,
wherein during the exposure of the photoresist layer, the photoresist layer is in vacuum contact with the phase mask.
11. The process according to claim 1 ,
wherein the thickness of the photoresist layer is at most 200 nm.
12. The process according to claim 1 ,
wherein the photoresist layer prior to exposure is covered by a reflection-reducing layer.
13. The process according to claim 1 ,
wherein during the exposure of the photoresist layer, the distance between this layer and the phase mask is between 2 microns and 100 microns.
14. The process according to claim 1 ,
wherein the etch process is reactive ion etching.
15. The process according to claim 1 ,
wherein the material of the substrate essentially is quartz, silicon, thermally oxidised silicon, germanium, silicon-germanium, a III-V compound semiconductor, or lithium niobate.
16. The process according to claim 1 ,
wherein at least one transparent layer having a refractive index different from that of the substrate is applied to the surface portion after applying the grating structure.
17. The process according to claim 16 ,
wherein the grating structure and the transparent layer are formed in such a way that the coupling angle (θ) changes by at most 0.1°/cm along the line and the absolute value of deviation of the coupling angle (θ) from a target value does not exceed 0.5°.
18. The process according to claim 16 ,
wherein the transparent layer is applied by reactive DC magnetron sputtering, in particular pulsed DC sputtering or AC-superimposed DC sputtering.
19. The process according to claim 16 ,
wherein the thickness of the transparent layer is between 50 nm and 5000 nm.
20. The process according to claim 16 ,
wherein the material of the transparent layer is Ta 2 0 5 , Nb 2 0 5 , Ti0 2 , Zr0 2 , A1 2 0 3 , Si0 2 —TiO 2 , Hf0 2 , Y 2 0 3 , SiO x N y , Si 3 N 4 , HfO x N y , AlO x N y , TiO x N y , MgF 2 or CaF 2 .
21. Optical element, produced by the process according to claim 1 .
22. The process according to claim 1 , wherein said angle departs by no more than 5°.
23. The process according to claim 2 , wherein the extension of the at least one grating structure is at least 1 cm parallel to the lines.
24. The process according to claim 7 , wherein the nontransparent material is metal.
25. The process according to claim 24 , wherein the metal is chromium.
26. The process according to claim 14 , wherein the reactive ion etching is with a gas containing at least one of Ar, CHClF 2 , CHF 3 .