Foreignfiling_text P24-015 - 1 - Formulation Field of the invention The present invention relates to a formulation comprising a metal oxide 5 precursor, use of a formulation, method for preparing a formulation, method for preparing a composite, a composite, an optical device and a display device. Background Art 10 Leading edge optical devices typically include optical gratings made from composite materials having a substrate as a support and complex and interlaced patterns thereon, the patterns being made up of different layers or stacks of layers. Usually, the creation of such complex and interlaced patterns demands for structuring processes, which become increasingly 15 challenging with decreasing size of structural dimensions to be prepared. In addition to a wide range of possible uses in various fields of application, such as in spectrometers or in optical storage systems (CD, DVD, etc.), diffractive gratings are the core components of so-called XR devices, 20 usually in the form of glasses. In this context, R stands for the term reality and X denotes different attributes such as, for example, virtual, augmented, mixed and so forth. Hence, diffractive gratings form part of the core of the so-called optical engine in XR devices, specifically in augmented reality and mixed reality glasses. Virtual reality glasses, when built as a head mounted 25 display, are often composed of a conventional liquid crystal (LC) organic light emitting diode (OLED) display being embedded in the device directly in front of the eyes of the user, and thus do not necessarily require diffractive gratings. In contrast, augmented and mixed reality glasses are designed to enable consumers to obtain visual impressions of their environment, at its 30 best as if they would not wear any glasses at all. However, they also make it possible to provide and serve digital information and to also project it into the field of vision of individuals. Additional digital information is gathered
Foreignfiling_text P24-015 - 2 - from recognizing and analyzing the environment, the individual inspects or looks at. To convey and project supporting digital information into the eyes of an individual, the augmented or mixed reality glasses are equipped with an information supply unit, which is coupled to an optical waveguide system 5 that transports the optically coded supporting information through it directly to the lens of the glasses. Here, the information passes a diffractive grating which couples the incident light into the lens and splits it according to its angular information and its spectral bands by diffraction. After incoupling of the light, the lens serves as waveguide enabling transport of the light to and 10 into the pupil of an individual. The location of light incoupling is independent of any preferred position and thus of the implication of technical needs. The direction of traversal of light within the lenses is determined by the diffractive grating diffracting or splitting the light. At certain positions in the lens, a second and a third diffractive grating serves for changing the 15 direction of light traversal and thereby enforcing the light to be projected into pupil of the user. The light traversal in the glasses is accomplished by total internal reflection (TIR) of the light, thus bouncing several times between the glass interfaces until reaching another diffractive grating, which changes the internal TIR direction of the light (see Figure 2). The 20 second and third grating are geometrically aligned in different directions with respect to the first and incoupling grating, e. g. by a certain angular distortion of the longitudinal axis, thus allowing to change the direction of propagation of totally internally reflected light. Needless to say, the lens itself or the material of which lenses are made of shall not be absorbing. 25 Otherwise, the supportive information never reaches the pupil of the user or only with strongly depleted light intensity. The process works regardless of the use of reflection or transmission gratings. Usually, the lenses are equipped with both types of gratings to properly guide the light. It should also be mentioned that there are differences in the optical performance of 30 reflection and transmission gratings, which, however, are of no further interest in the context of the current invention. The basic structure of the gratings is very similar, which is more important at this point.
Foreignfiling_text P24-015 - 3 - Nevertheless, there are different designs and structures such as surface relief (SR) or volume phase holographic (VPH) gratings to achieve waveguide. Both types are very similar in appearance. In the simplest case, 5 the gratings are mounted onto the surface of a waveguiding material, here the lens. The grating itself is composed of an array of fine structures, mostly trenches of a first material type Material 01 with a refractive index RI 01, however, not limited thereto. The geometrical shape of the trenches may be manifold, from rectangular, over V-shaped trenches, U-shaped and there 10 like. The width, including structures with different widths, the geometrical form of the trenches, their pitch as well as their depth, including different depths, are specially designed to influence the diffraction pattern of the incident light to be diffracted. 15 In case of VPH gratings, the trenches or structures of a first material type (Material 01) having a refractive index (RI 01) are filled by a second material type (Material 02) having a refractive index (RI 02), wherein RI 02 is incrementally different from RI 01 (see Figures 1 and 3). For the sake of completeness, it should be mentioned that Material 01 or Material 02 may 20 be composed of a stack of structured layers, each containing a different material composition with different refractive index, stacked on top of each other, thereby forming Material 01 or Material 02 having an effective or graded refractive index RI 01 or RI 02, respectively. Incidentally, the (effective or graded) refractive indices RI 01 and RI 02 depend on the 25 refractive index of the waveguide or the lens from which the glasses are made of. If a glass lens with high refractive index (n03 > 1.46) is used, the (effective or graded) refractive indices of Material 01 and Material 02 are considered to be higher than that of the lens itself, whereby a RI value of 2.0 can be reached and exceeded. Surface relief (SR) gratings may look 30 similar and may also include a second type of material as a filler for the trenches, but the trenches can also be just air. High performance gratings, especially those of VPH-type, may be manufactured using standard
Foreignfiling_text P24-015 - 4 - lithography and deposition techniques known from micro-fabrication such as, for example, the manufacturing of integrated circuits. Such standard techniques typically include physical vapor deposition (PVD) 5 or chemical vapor deposition (CVD) processes and often suffer from incomplete gap filling due to unfavourable deposition and/or layer growth deposition properties including increased deposition and/or growth rates at corners and edges. Such incomplete gap filling results in the formation of voids within the structures to be filled by the PVD- and CVD-materials. In 10 addition to the formation of voids, the surface of the substrate is covered by a PVD and/or CVD layer that is almost as thick as the maximum depth of the deepest structure to be filled by the deposited gap filling material (see Figures 4 and 5). In some applications, however, it may be necessary to expose the surface of the substrate so that it is available for further 15 processing. Consequently, undesired overburden layers from PVD or CVD need to be removed, for example by chemical mechanical planarization (CMP) without harming the original substrate surface underneath. Although CMP is very well established in the process of manufacturing integrated circuits, CMP is a time consuming and costly process and can be seen as a 20 potential economic drawback for mass production of leading-edge optical devices, particularly the mass production of diffractive gratings. It would therefore be desirable to have a solution for an advanced and cost-efficient manufacturing of optical gratings where gap filling does not require CMP (see Figure 6). 25 For that reason, more cost-effective production technology allowing for lower cost of ownership is needed.
Foreignfiling_text P24-015 - 5 - Summary of the invention The inventors newly have found that there are still one or more considerable problems for which improvement is desired, as listed below: expanding the parameter space that allows adjusting the optical parameters 5 / optical properties of an obtained optical layer/composite through the combination of at least two metal precursors, optimizing the solid content in a formulation by improving the solubility of metal precursors, changing/optimizing solvents of a formulation, providing a printable formulation for preparing an optical layer/composite containing a material 10 which provides sufficiently high refractive indices after curing, namely after lower temperature curing providing a formulation for fabricating an optical layer/composite which enables to prepare a dense, crack-less or crack-free optical layer and enables to fill up of cavities, trenches or gaps after curing; providing a formulation for preparing an optical layer/composite containing 15 a metal oxide precursor material of a high refractive index material, which is well dispersed in the formulation; realizing improved layer uniformity of a resulting film, preferably realizing improved layer uniformity of a resulting film by using a formulation containing high solid content of metal oxide precursor(s), simpler and/or cost-efficient method for preparing an optical 20 layer/composite with using the formulation; realizing a more stable formulation, providing suitable formulation for wet printing, namely for spin- coating or ink jetting, realizing continuous inkjet printing. The inventors aimed to solve one or more of the above-mentioned 25 problems. Then, the present inventors have surprisingly found that one or more of the above-described technical problems may be solved by the features as defined in the claims. 30 Namely, it is found a novel formulation, preferably to be used for forming an optical layer comprising a metal oxide, comprising at least a 1st metal oxide
Foreignfiling_text P24-015 - 6 - precursor, a 2nd metal oxide precursor different from the 1st metal oxide precursor, and a solvent, - - wherein said 1st metal oxide precursor is a metal alkoxide or a metal carboxylate containing a metal element selected from the group consisting of group 1 elements of the periodic table, group 4 5 elements, group 5 elements, group 6 elements, group 12 elements, group 14 elements and group 15 elements of the periodic table; - wherein said 2nd metal oxide precursor is a metal halide, metal alkoxide or a metal carboxylate containing a metal element selected from the group consisting of group 1 elements of the periodic table, group 4 elements, 10 group 5 elements, group 6 elements, group 12 elements, group 14 elements and group 15 elements of the periodic table. In another aspect, the present invention also relates to use of the formulation of the present invention for preparing a composite, preferably 15 for preparing a layered composite, more preferably for preparing an optical layer or for filling one or more trenches of a patterned surface or an uneven surface of a substrate. In another aspect, the present invention further relates to a method for 20 preparing a formulation of the present invention, comprising at least, essentially consisting of, or consisting of; following step (A): (A) Mixing a 1st metal oxide precursor, a 2nd metal oxide precursor different from the 1st metal oxide precursor, and a solvent, - wherein said 1st metal oxide precursor is a metal alkoxide or a metal 25 carboxylate containing a metal element selected from the group consisting of group 1 elements of the periodic table, group 4 elements, group 5 elements, group 6 elements, group 12 elements, group 14 elements and group 15 elements of the periodic table; and - wherein said 2nd metal oxide precursor is a metal halide, metal alkoxide or 30 a metal carboxylate containing a metal element selected from the group consisting of group 1 elements of the periodic table, group 4 elements,
Foreignfiling_text P24-015 - 7 - group 5 elements, group 6 elements, group 12 elements, group 14 elements and group 15 elements of the periodic table. In another aspect, the present invention further relates to a method for 5 preparing a composite containing a metal oxide, preferably said metal oxide is selected from metal monoxide, metal dioxide and metal pentoxide, or a combination of these; comprising the following steps (a) and (b): (a) providing the formulation of the present invention onto a surface of a substrate, preferably by wet deposition process, more preferably by spin- 10 coating or an area selective printing, preferably said area selective printing is ink-jetting; and (b) applying a thermal treatment to the formulation provided on the surface of the substrate to convert at least a part of the metal oxide precursor of the formulation to a metal oxide. 15 Preferably said composite being a layered composite, more preferably said layered composite is an optical layer. In another aspect, the present invention further relates to a composite, preferably being a layered composite, preferably said layered composite is 20 an optical layer, obtained or obtainable by the method of the present invention. In another aspect, the present invention further relates to a composite, preferably being a layered composite, preferably said layered composite is 25 an optical layer, derived from the formulation of the present invention. In another aspect, the present invention further relates to an optical device comprising the composite of the present invention, and a substrate comprising a patterned surface or an uneven surface. Preferably a gap or 30 trench of said patterned surface or an uneven surface of the substrate is at least partly filled with said composite.
Foreignfiling_text P24-015 - 8 - Preferably said substrate is a patterned substrate comprising topographical features on the surface thereof. Preferably said composite fills at least a part of a gap of said topographical features, more preferably said composite fills a trench of the patterned substrate. 5 In another aspect, the present invention further relates to a display device comprising at least one functional medium configured to direct and modulate a light or configured to emit light; and the composite of the present invention. 10 Technical effects of the invention The present invention may provide one or more of following effects; expanding the parameter space that allows adjusting the optical parameters / optical properties of an obtained optical layer/composite through the 15 combination of at least two metal precursors, optimizing the solid content in a formulation by improving the solubility of metal precursors, changing/optimizing solvents of a formulation, providing a printable formulation for preparing an optical layer/composite containing a material which provides sufficiently high refractive indices after curing, namely after 20 lower temperature curing providing a formulation for fabricating an optical layer/composite which enables to prepare a dense, crack-less or crack-free optical layer and enables to fill up of cavities, trenches or gaps after curing; providing a formulation for preparing an optical layer/composite containing a metal oxide precursor material of a high refractive index material, which is 25 well dispersed in the formulation; realizing improved layer uniformity of a resulting film, preferably realizing improved layer uniformity of a resulting film by using a formulation containing high solid content of metal oxide precursor(s), simpler and/or cost-efficient method for preparing an optical layer/composite with using the formulation; realizing a more stable 30 formulation, providing suitable formulation for wet printing, namely for spin- coating or ink jetting, realizing continuous inkjet printing.
Foreignfiling_text P24-015 - 9 - Preferred embodiments of the present invention are described hereinafter and in the dependent claims. Brief description of the figures 5 Fig.1: Schematic cross-sectional view of a VPH grating with a Material 01 and a Material 02, wherein the refractive index IR 01 of Material 01 is incrementally different to the refractive index IR 02 of Material 02. Fig.2: Schematic cross-sectional view of a VPH grating enabling light diffraction (transmissive case) including propagation of diffracted light within 10 waveguide (e.g. lens) by total internal reflection. Fig.3: Schematic cross-sectional view of a VPH grating providing gaps (trenches) to be filled with a high refractive index material (Material 02), wherein the refractive index of Material 02 is incrementally different form the refractive index of Material 01 flanking the gaps (trenches). 15 Fig.4: Schematic representation of PVD- or CVD-mediated gap filling process and removal of undesired overburden. Fig.5: Schematic representation of PVD- or CVD-mediated gap filling process creating and leaving voids within gaps and deposited layers. Fig.6: Schematic representation of gap filling process using formulations 20 containing inventive metal complex or formulations thereof being converted to metal oxides. Fig.7a: a SEM image of Sample 1 (Formulation 1, 150°C/5min, 150nm trench width) Fig.7b: a SEM image of Sample 4 (Formulation 1, 150°C/5min, 100nm 25 trench width). List of reference signs 1. Material 02 with RI 02 2. Material 01 with RI 01 30 3. Substrate (e.g. glass) 4. Diffraction of incident light represented by broad arrow 5. Total internal reflection of light (TIR)
Foreignfiling_text P24-015 - 10 - 6. Waveguide 7. Structured layer stack with gaps (trenches) 8. Substrate (e.g. glass or silicon) 9. Overburden of material (e.g. high refractive index material or high etch 5 resistant material) 10. Material (e.g. high refractive index material or high etch resistant material) providing gap fill 11. Voids 12. Formulation (e.g. ink) of high refractive index material (e.g. metal oxide 10 precursor) 13. High refractive index material (e.g. metal oxide) providing gap fill with optional concave geometry 14. Overburden layer (optional) 15. Energy 15 Definition of the terms In the context of the present invention, the term “formulation medium” or the plural term “formulation media” as used herein, denote one or more compounds serving as a solvent, suspending agent, carrier and/or matrix 20 for the metal oxide precursor compound and any other component included in the formulation. Formulation media are generally inert compounds that do not react with said metal oxide precursor compounds and said other components. Formulation media may be liquid compounds, solid compounds or mixtures thereof. Typically, formulation media are organic 25 compounds. The term “surfactant” as used herein, refers to an additive that reduces the surface tension of a given formulation. 30 The term “wetting and dispersion agent” as used herein, refers to an additive that increases the spreading and filling properties of a given
Foreignfiling_text P24-015 - 11 - formulation. In this way, the tendency of the molecules to adhere to each other is reduced. The term “adhesion promoter” as used herein, refers to an additive that 5 increases the adhesion of a given formulation. The term “polymer matrix” as used herein, refers to an additive that acts as a macromolecular matrix for one or more components of a given formulation. 10 The term “optical device” as used herein, relates to a device containing one or more optical components for forming a light beam including, but not limited to, gratings, lenses, prisms, mirrors, optical windows, filters, polarizing optics, UV and IR optics, and optical coatings. Preferred optical 15 devices in the context of the present invention are augmented reality (AR) glasses and/or virtual reality (VR) glasses. The term “display device” as used herein, is a kind of an optical device configured to output/present information in visual or tactile form. Examples 20 are Liquid crystal display (LCD), Light emitting diode display (LED display), organic light emitting display (OLED), micro-LED display, quantum dot display (QLED), AR/VR display, plasma (PDP) display, electroluminescent (ELD) display. 25 Detailed description of the invention The present invention relates to a formulation, preferably to be used for for forming an optical layer comprising a metal oxide, comprising at least, essentially consisting of, or consisting of; a 1st metal oxide precursor, a 2nd metal oxide precursor different from the 30 1st metal oxide precursor, and a solvent, - wherein said 1st metal oxide precursor is a metal alkoxide or a metal carboxylate containing a metal element selected from the group consisting
Foreignfiling_text P24-015 - 12 - of group 1 elements of the periodic table, group 4 elements, group 5 elements, group 6 elements, group 12 elements, group 14 elements and group 15 elements of the periodic table; - wherein said 2nd metal oxide precursor is a metal halide, metal alkoxide or 5 a metal carboxylate containing a metal element selected from the group consisting of group 1 elements of the periodic table, group 4 elements, group 5 elements, group 6 elements, group 12 elements, group 14 elements and group 15 elements of the periodic table. 10 - 1st Metal oxide precursor According to the present invention, said 1st metal oxide precursor is a metal alkoxide or a metal carboxylate containing a metal element selected from the group consisting of group 1 elements of the periodic table, group 4 elements, group 5 elements, group 6 elements, group 12 elements, group 15 14 elements and group 15 elements of the periodic table. As said 1st metal oxide precursor, a publicly known metal oxide precursor material that is metal alkoxide or a metal carboxylate containing a metal element selected from the group consisting of group 1 elements of the 20 periodic table, group 4 elements, group 5 elements, group 6 elements, group 12 elements, group 14 elements and group 15 elements of the periodic table, can be used. In a preferred embodiment, the 1st metal oxide precursor is a metal alkoxide 25 represented by any one of the following chemical formulae (I) to (VI); Ma1O1Ra1 - (I) Ma2O2(Ra1Ra2) - (II) Ma3O3(Ra1Ra2Ra3) - (III) 30 Ma4O4(Ra1Ra2Ra3Ra4) - (IV) Ma5O5(Ra1Ra2Ra3Ra4Ra5) - (V) Ma6O6(Ra1Ra2Ra3Ra4Ra5Ra6) - (VI)
Foreignfiling_text P24-015 - 13 - wherein Ma1 is a monovalent alkali metal, preferably Ma1 is K, Na or Li; Ma2 is a divalent metal, preferably Ma2 is selected from Zn or Sn; 5 Ma3 is a trivalent metal, preferably Ma3 is Bi; Ma4 is a quadrivalent metal selected from Zr, Ti or Hf; Ma5 is a pentavalent metal selected from V, Nb or Ta; Ma6 is Mo or W; and Ra1, Ra2, Ra3, Ra4, Ra5 and Ra6 are each independently selected from a 10 straight-chain alkyl group having 1 to 25 carbon atoms, preferably 1 to 15 carbon atoms, more preferably 1 to 10 carbon atoms; a branched or cyclic alkyl group having 3-25 carbon atoms, preferably 3 to 15 carbon atoms, more preferably 3 to 10 carbon atoms; an aryl group having 3 to 25 carbon atoms, preferably from 3 to 15 carbon atoms, more preferably 3 to 10 15 carbon atoms; a straight chain alkyl-cycloalkyl group having 4 to 25 carbon atoms, preferably 4 to 15 carbon atoms; branched chain alkyl-cycloalkyl group having carbon atoms 6 to 25 carbon atoms, preferably 6 to 15 carbon atoms; a straight chain alkyl-aryl group having 4 to 25 carbon atoms, preferably 4 to 15 carbon atoms; branched chain alkyl-aryl group having 6 20 to 25 carbon atoms, preferably 6 to 15 carbon atoms; where one or more non-adjacent CH2 groups and/or one or more adjacent CH2 groups of the above-mentioned groups may be replaced by oxygen atom, and where one or more H atoms maybe replaced by D; where each of groups may be substituted by one or more groups Rax; 25 Rax is at each occurrence, identically or differently, a straight chain alkyl or alkoxy group having 1 to 15 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms; a branched or cyclic alkyl or alkoxy group having 3 to 15 carbon atoms, preferably 3 to 10 carbon atoms, more 30 preferably 3 to 5 carbon atoms; a straight-chain alkenyl or alkynyl group having 2 to 15 carbon atoms, preferably 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms; a branched alkenyl group or alkynyl group
Foreignfiling_text P24-015 - 14 - having 3 to 15 carbon atoms, preferably 3 to 10 carbon atoms, more preferably 3 to 5 carbon atoms; an aromatic or heteroaromatic ring system having 5 to 15 aromatic ring atoms, preferably 5 to 10 aromatic ring atoms; where in each of the above-mentioned groups, one or more H atoms may 5 be replaced by D and where two or more adjacent substituents Ra here may optionally form a mono- or polycyclic, aliphatic ring system with one another. Examples of 1st metal alkoxide is K alkoxide, Na alkoxide, Li alkoxide, Zn 10 alkoxide, Sn alkoxide, Bi alkoxide, Zr alkoxide, Ti alkoxide, Hf alkoxide, V alkoxide, Nb alkoxide, Ta alkoxide, Mo alkoxide, W alkoxide or a combination of any of these. Preferably said alkoxide is butoxide, ethoxide, iso-propoxide or methoxide, more preferably it is ethoxide, methoxide or iso-propoxide. 15 More preferably, said 1st metal alkoxide is selected from potassium ethoxide, potassium methoxide, sodium ethoxide, sodium methoxide, lithium ethoxide, lithium methoxide, zinc ethoxide, zinc methoxide, tin ethoxide, tin methoxide, bismuth ethoxide, bismuth methoxide, zirconium 20 ethoxide, zirconium methoxide, titanium ethoxide, titanium methoxide, hafnium ethoxide, hafnium methoxide, vanadium ethoxide, vanadium methoxide, niobium methoxide, niobium ethoxide (Nb(OEt)5), tantalum methoxide, tantalum ethoxide, molybdenum methoxide, molybdenum ethoxide, tungsten methoxide, tungsten ethoxide or any combination of any 25 of them. - 2nd Metal oxide precursor According to the present invention, said 2nd metal oxide precursor is a metal halide, metal alkoxide or a metal carboxylate containing a metal element 30 selected from the group consisting of group 1 elements of the periodic table, group 4 elements, group 5 elements, group 6 elements, group 12 elements, group 14 elements and group 15 elements of the periodic table.
Foreignfiling_text P24-015 - 15 - In a preferred embodiment, said 2nd metal oxide precursor is a metal alkoxide represented by any one of the following chemical formulae (I’) to (VI’), or a metal halide of any one of chemical formulae (VII) to (XII); 5 Ma1’O1Ra1’ - (I’) Ma2’O2(Ra1’Ra2’) - (II’) Ma3’O3(Ra1’Ra2’Ra3’) - (III’) Ma4’O4(Ra1’Ra2’Ra3’Ra4’) - (IV’) 10 Ma5’O5(Ra1’Ra2’Ra3’Ra4’Ra5’) - (V’) Ma6’O6(Ra1’Ra2’Ra3’Ra4’Ra5’Ra6’) - (VI’) wherein Ma1’ is a monovalent alkali metal, preferably Ma1’ is K, Na or Li; 15 Ma2’ is a divalent metal, preferably Ma2’ is selected from Zn or Sn; Ma3’ is a trivalent metal, preferably Ma3’ is Bi; Ma4’ is a quadrivalent metal selected from Zr, Ti or Hf; Ma5’ is a pentavalent metal selected from V, Nb or Ta; Ma6’ is Mo or W; and 20 Ra1’, Ra2’, Ra3’, Ra4’, Ra5’ and Ra6’ are each independently selected from a straight-chain alkyl group having 1 to 25 carbon atoms, preferably 1 to 15 carbon atoms, more preferably 1 to 10 carbon atoms; a branched or cyclic alkyl group having 3-25 carbon atoms, preferably 3 to 15 carbon atoms, more preferably 3 to 10 carbon atoms; an aryl group having 3 to 25 carbon 25 atoms, preferably from 3 to 15 carbon atoms, more preferably 3 to 10 carbon atoms; a straight chain alkyl-cycloalkyl group having 4 to 25 carbon atoms, preferably 4 to 15 carbon atoms; branched chain alkyl-cycloalkyl group having carbon atoms 6 to 25 carbon atoms, preferably 6 to 15 carbon atoms; a straight chain alkyl-aryl group having 4 to 25 carbon atoms, 30 preferably 4 to 15 carbon atoms; branched chain alkyl-aryl group having 6 to 25 carbon atoms, preferably 6 to 15 carbon atoms;
Foreignfiling_text P24-015 - 16 - where one or more non-adjacent CH2 groups and/or one or more adjacent CH2 groups of the above-mentioned groups may be replaced by oxygen atom, and where one or more H atoms may be replaced by D; where each of groups may be substituted by one or more groups Rax; 5 Rax is at each occurrence, identically or differently, a straight chain alkyl or alkoxy group having 1 to 15 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms; a branched or cyclic alkyl or alkoxy group having 3 to 15 carbon atoms, preferably 3 to 10 carbon atoms, more 10 preferably 3 to 5 carbon atoms; a straight-chain alkenyl or alkynyl group having 2 to 15 carbon atoms, preferably 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms; a branched alkenyl group or alkynyl group having 3 to 15 carbon atoms, preferably 3 to 10 carbon atoms, more preferably 3 to 5 carbon atoms; an aromatic or heteroaromatic ring system 15 having 5 to 15 aromatic ring atoms, preferably 5 to 10 aromatic ring atoms; where in each of the above-mentioned groups, one or more H atoms may be replaced by D and where two or more adjacent substituents Ra here may optionally form a mono- or polycyclic, aliphatic ring system with one another; 20 Mb1Xb1 - (VII) Mb2Xb22 - (VIII) Mb3Xb33 - (IX) Mb4Xb44 - (X) 25 Mb5Xb55 - (XI) Mb6Xb66 - (XII) wherein Mb1 is a monovalent alkali metal, preferably Mb1 is K, Na or Li; Mb2 is a divalent metal, preferably Mb2 is selected from Zn or Sn; 30 Mb3 is a trivalent metal, preferably Mb3 is Bi; Mb4 is a quadrivalent metal selected from Zr, Ti or Hf; Mb5 is a pentavalent metal selected from V, Nb or Ta;
Foreignfiling_text P24-015 - 17 - Mb6 is Mo or W; and Xb1, Xb2, Xb3, Xb4, Xb5, Xb6 are each independently a halogen, preferably Xb1, Xb2, Xb3, Xb4, Xb5, Xb6 are each independently selected from F, Cl, Br, I, more preferably Xb1, Xb2, Xb3, Xb4, Xb5, Xb6 are Cl. 5 Even more preferably, said 2nd metal oxide precursor is a metal halide represented by any one of chemical formulae (VII) to (XII). In a preferred embodiment of the present invention, the weight ratio of the 2nd metal oxide precursor to the 1st metal oxide precursor is in the range 10 from 0.01 to 99. Preferably in the range from 0.1 to 10, more preferably from 0.5 to 5. As said 2nd metal oxide precursor, a below described publicly known metal oxide precursor can be used preferably. Such metal oxide precursor is 15 selected from a metal halide, metal alkoxide or a metal carboxylate containing a metal element selected from the group consisting of group 1 elements of the periodic table, group 4 elements, group 5 elements, group 6 elements, group 12 elements, group 14 elements and group 15 elements of the periodic table. 20 Examples of 2nd metal halide is Sn halides, W halides, Ta halides, Sn halides, Zr halides, Zn halides, Bi halides, Mo halides, Ti halides, V halides, Hf halides or a combination of any of these. 25 More preferably, said 2nd metal halide precursor is selected from ZnCl2, SnCl2, BiCl3, ZrCl4, TiCl4, HfCl4, TaCl5, NbCl5, VCl5, WCl6, MoCl6 or a combination of any of these. According to the present invention, the total content of all metal oxide 30 precursors in the formulation is in the range from 0.1 w% to 50 w% based on the total mass of the formulation, preferably it is from 1wt.% to 30wt.%, more preferably from 5 to 20wt.%.
Foreignfiling_text P24-015 - 18 - It is believed that the above-mentioned total amount of the metal halide precursors based on the total amount of formulation is suitable to realize an improved gap filling or fabricating a thin layer placed directly onto a 5 patterned surface or directly onto an uneven surface of a substrate / under layer. -Solvent According to the present invention, the formulation of the present invention 10 contains a solvent. In a preferred embodiment of the present invention, the solvent is an organic solvent. Preferably said organic solvent is selected from one or more members of the group consisting of alcohols, glycols, ethers, ketones, 15 esters, hydrocarbons, aromatic hydrocarbons, amides and sulfones. More preferably said organic solvent is selected from one or more members of the group consisting of ethylene glycol monoalkyl ethers, preferably it is ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether and/or ethylene glycol monobutyl ether; 20 diethylene glycol dialkyl ethers, preferably it is diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether and/or diethylene glycol dibutyl ether; propylene glycol monoalkyl ethers, preferably it is propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether and/or propylene glycol monopropyl ether; ethylene 25 glycol alkyl ether acetates, preferably it is methyl cellosolve acetate and/or ethyl cellosolve acetate; propylene glycol alkyl ether acetates, preferably it is propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether acetate and/or propylene glycol monopropyl ether acetate; ketones, preferably it is methyl ethyl ketone, 30 acetone, methyl amyl ketone, methyl isobutyl ketone and/or cyclohexanone; alcohols, preferably it is ethanol, propanol, 1,3-dimethoxy-2-propanol, butanol, hexanol, cyclo hexanol, ethylene glycol, propylene glycol,
Foreignfiling_text P24-015 - 19 - triethylene glycol, glycerin, pentanols, preferably it is 1-pentanol, 2-pentnol, 3-pentanol, 3-ethyl-3-pentanol, 2,4-dimethyl-3-pentanol; esters, preferably it is ethyl 3-ethoxypropionate, methyl 3-methoxypropionate and/or ethyl lactate; and cyclic esters, preferably it is gamma-butyro-lactone; 5 preferably said solvent is selected from propylene glycol alkyl ether acetates, ethylene glycol monoalkyl ethers, propylene glycol and propylene glycol monoalkyl ethers, 1-pentanol, 2-pentnol, 3-pentanol, 3-ethyl-3- pentanol, 2,4-dimethyl-3-pentanol 1,3-dimethoxy-2-propanol or a mixture of any one of them. 10 It is believed that the printing, especially ink jetting of structures is considered as a highly cost-efficient production step. Spin-coating is a convenient method and is preferable to form a uniform thin layer. Thus, suitable solvents of the formulation for spin-coating/inkjet printing the 15 structures or filling up of cavities and structures, is described here. After printing, deposition and fill up of structures, at least a part of the material as the metal halide precursor needs to become converted into the respective metal oxides by any known means know to the persons skilled in 20 the art (thermally, photochemically, etc.). - Water According to the present invention, the formulation contains water, and the stoichiometric amount of water is in the range from 100 to 400 mol% based 25 on the total amount of metal oxide precursor, preferably the stoichiometric amount of water based on the total amount of the metal oxide precursor is in the range from 150 to 300 mol%, even more preferably from 180 to 270 mol%. 30 -Additives
Foreignfiling_text P24-015 - 20 - In some embodiments of the present invention, the formulation may optionally comprise one or more additives selected from surfactants, wetting and dispersion agents, adhesion promoters, and polymer matrices. Or, in some embodiments, the formulation of the present invention does not 5 comprise any additives. In a preferred embodiment of the present invention, the formulation is an ink formulation being suitable for inkjet printing. Typical requirements for ink formulations are surface tensions in the range from 20 mN/m to 30 mN/m 10 and viscosities in the range from 5 mPa·s to 30 mPa·s. -Use In another aspect, the present invention also relates to use of the formulation of the present invention for preparing a composite, preferably 15 for preparing a layered composite, more preferably for preparing an optical layer or for filling one or more trenches of a patterned surface or an uneven surface of a substrate. -Method for preparing a formulation 20 In another aspect, the present invention also relates to a method for preparing a formulation of the present invention, containing at least, essentially consisting of or consisting of, the following steps; following step (A): (A) Mixing a 1st metal oxide precursor, a 2nd metal oxide precursor different 25 from the 1st metal oxide precursor, and a solvent, - wherein said 1st metal oxide precursor is a metal alkoxide or a metal carboxylate containing a metal element selected from the group consisting of group 1 elements of the periodic table, group 4 elements, group 5 elements, group 6 elements, group 12 elements, group 14 elements and 30 group 15 elements of the periodic table; and - wherein said 2nd metal oxide precursor is a metal halide, metal alkoxide or a metal carboxylate containing a metal element selected from the group
Foreignfiling_text P24-015 - 21 - consisting of group 1 elements of the periodic table, group 4 elements, group 5 elements, group 6 elements, group 12 elements, group 14 elements and group 15 elements of the periodic table. 5 -Method for preparing a composite containing a metal oxide In another aspect, the present invention also relates to a method for preparing a composite containing a metal oxide, preferably said metal oxide is selected from metal monoxide, metal dioxide or metal pentoxide, or a combination of these; comprising at least the following steps (a) and (b): 10 (a) providing the formulation of the present invention onto a surface of a substrate or a surface of an under layer placed on a substrate, preferably by wet deposition process, more preferably by spin-coating or ink-jetting, even more preferably by ink-jetting; and (b) applying a thermal treatment to the formulation provided on the surface 15 of the substrate or on the surface of the underlayer placed on the substrate to convert at least a part of the metal oxide precursor of the formulation to a metal oxide. Preferably said composite being a layered composite, more preferably said layered composite is an optical layer. 20 -Step (a) According to the present invention, said formulation may preferably be provided onto a surface of a substrate or a surface of an underlayer by wet deposition process. Said wet deposition process is drop casting, coating, or 25 printing. A more preferred coating method is spin-coating, spray coating, slit coating, or slot-die coating. A more preferred printing method is flexo printing, gravure printing, inkjet printing, EHD printing, offset printing, or screen printing. Furthermore, preferred printing method is spray coating and inkjet printing and the most preferred one is inkjet printing. 30 Thus, in a preferred embodiment, the formulation is applied onto a surface of a substrate or a surface of an underlayer by spin-coating or ink-jetting in
Foreignfiling_text P24-015 - 22 - step (a). From a viewpoint of cost effectiveness, ink-jetting can preferably be used. In a preferred embodiment of the present invention, the formulation 5 provided in step (a) of the method is an ink formulation being suitable for inkjet printing. Typical requirements for ink formulations are surface tensions in the range from 20 mN/m to 30 mN/m and viscosities in the range from 5 mPa·s to 30 mPa·s. 10 Depending on the specific problem to be solved, the formulation needs to be deposited either as a homogeneous, dense and thin layer covering the entire surface of the substrate or the entire surface of an underlayer by a coating method or the formulation needs to be deposited locally in a structured manner, thus requiring for a printing method. Both, coating and 15 printing methods require formulations to be formulated in an adequate manner to comply with the physico-chemical needs of the respective coating and printing method as well as to comply with certain needs regarding the surface of the substrate to be coated or printed. 20 In a preferred embodiment of the method of the present invention, the surface of the substrate is pre-treated by a surface cleaning process. Preferred surface cleaning processes are silicon wafer cleaning processes such as described in W. Kern, The Evolution of Silicon Wafer Cleaning Technology, J. Electrochem. Soc., Vol.137, 6, 1990, 1887-1892 and in 25 New Process Technologies for Microelectronics, RCA Review 1970, 31, 2, 185-454. Such silicon wafer cleaning processes include wet cleaning process involving cleaning solvents (e.g., isopropanol (IPA)); wet etching processes involving hydrogen peroxide solutions (e.g., piranha solution, SC1, and SC2), choline solutions, or HF solutions; dry etching processes 30 involving chemical vapor etching, UV/ozone treatments or glow discharge techniques (e.g., O2 plasma etching); and mechanical processes involving brush scrubbing, fluid jet or ultrasonic techniques (sonification). The surface
Foreignfiling_text P24-015 - 23 - of the substrate can also be pre-treated by salinization or an atomic layer deposition (ALD) process. The pre-treatment of the surface of the substrate serves to modify the hydrophobicity/hydrophilicity of the surface. This can improve the adhesion and filling characteristics of the optical metal oxide 5 layer on the surface of the substrate. In a more preferred embodiment, a wet cleaning process involving cleaning solvents (e.g., isopropanol (IPA)) is combined with one or more of a wet etching process involving hydrogen peroxide solutions (e.g., piranha 10 solution, SC1, and SC2), choline solutions, or HF solutions; dry etching process involving chemical vapor etching, UV/ozone treatments or glow discharge techniques (e.g., O2 plasma etching); and mechanical process involving brush scrubbing, fluid jet or ultrasonic techniques (sonification). 15 In a most preferred embodiment, a wet cleaning process involving cleaning solvents (e.g., isopropanol (IPA)) is combined with a mechanical process involving brush scrubbing, fluid jet or ultrasonic techniques (sonification) and with a wet etching process involving hydrogen peroxide solutions (e.g., piranha solution, SC1, and SC2), choline solutions, or HF solutions; 20 Thus, in a preferable embodiment, in step (a), the formulation is applied to a surface of a substrate or to a surface of an underlayer by spin-coating or ink-jetting. 25 In a preferable embodiment, the formulation is at least partly converted on the surface of the substrate or the surface of an underlayer to a composite, wherein said composite contains a metal oxide, preferably selected from metal monoxide, metal dioxide and/or metal pentoxide; and a metal oxide precursor. 30 In a preferable embodiment, the substrate is a patterned substrate comprising topographical features on the surface thereof. Said patterned
Foreignfiling_text P24-015 - 24 - structure of the substrate can be an underlayer placed over the substrate (e.g., an underlayer of a semiconducting device). -Step (b) 5 It is believed that the formulation is at least partly converted in step (b) on the surface of the substrate or on the surface of the underlayer to a metal oxide to form a composite by exposure to thermal treatment. Said composite is preferably a layered composite. And said solvent is usually removed in step (b). 10 Preferred thermal treatment includes exposure to elevated temperature from 50 to 600 °C, preferably it is from 80 to 500°C, more preferably from 100 to 300°C. It is believed that applying a higher temperature such as in the range from 100 - 600°C, preferably 125-450°C, more preferably from 15 150-250 °C can realize an improved gap fill. It is preferred to use the formulation containing a lower amount of the metal oxide precursor based on the total amount of the formulation in step (a) to realize an improved gap filing, for examples, in the range from 0.1 to 30wt% 20 based on the total amount of the formulation, more preferably in the range from 1 to 20wt%, even more preferably from 5 to 15wt% based on the total amount of the formulation; and applying a higher temperature in step (b) such as in the range from 100 - 600°C, preferably 125-450°C, more preferably from 150-250°C to realize an improved gap fill. 25 Thermal treatment method in Step (b) is not limited to any specific thermal treatment methods or times. Depending on the type of substrate and formulation, a person skilled in the art can determine suitable thermal treatment methods. 30 In some embodiments of the method for preparing an optical metal oxide layer according to the present invention, a pre-baking step can be applied
Foreignfiling_text P24-015 - 25 - before step (b) after step (a) to remove the solvent of the formulation. The formulation can also be partly converted on the surface of the substrate to an optical metal oxide layer by pre-baking (soft baking) at a temperature from 40 to 150 °C, preferably from 50 to 120 °C, more preferably from 60 to 5 100 °C; then, baking of step (b) (hard baking, sintering or annealing) at a temperature from 100 to 600 °C, preferably from 125 to 450 °C, more preferably from 150 to 255 °C is applied. Pre-baking (soft baking) serves the purpose to remove volatile and low 10 boiling components such as, e.g., volatile and low boiling formulation media or additives from the drop casted, coated or printed films. Pre-baking is preferably carried out for a period of 1 to 60 minutes. After pre-baking, layers of substrate adhering films of metal oxide precursor or metal oxide precursor mixtures are obtained. The films may still comprise residual 15 formulation media or additives. In an alternative preferred embodiment of the method for preparing an optical metal oxide layer according to the present invention, pre-baking is omitted so that the formulation is converted in step (b) on the surface of the 20 substrate or on the surface of the under layer to an optical metal oxide layer directly. Baking (hard baking, sintering or annealing) serves the purpose to convert the metal oxide precursor or metal oxide precursor mixture layers on the 25 substrate into a metal oxide layer. Moreover, the final properties of the metal oxide layer may be adjusted by the baking treatment. Baking is preferably carried out at the time in the range from 1 to 60min, preferably 2 to 20 min, more preferably 3 to 10min. 30 Said Pre-baking and baking (step (b)) may be carried out under ambient atmosphere or atmospheres with increased oxygen content to decompose unwanted organic components, which can lead to a lower activation energy
Foreignfiling_text P24-015 - 26 - when the composite is formed and is believed to improve the physical- chemical properties of the resulting layered composite material. In a preferred embodiment of the method of present invention, the substrate 5 or the underlayer is patterned comprising topographical features on the surface thereof, and the layered composite, preferably it is an optical layer, forms a coating layer covering the surface of the substrate and filling said topographical features. As a result, the topographical features are filled and levelled by said composition. 10 Preferred topographical features include, for example, gaps, grooves, trenches and vias. Topographical features may be distributed uniformly or non-uniformly over the surface of the substrate. Preferably, they are arranged as an array or grating on the surface of the substrate. It is 15 preferred that the topographical features have different lengths, widths, diameters as well as different aspect ratios. It is preferred that said topographical features have an aspect ratio of 1:20 to 20:1, more preferably 1:10 to 10:1. The aspect ratio is defined as width of structure to its height (or depth). From the viewpoint of dimension, the depth of the topographical 20 features is preferably in the range from 10 nm to 10 µm, more preferably 50 nm to 5 µm, and most preferably 100 nm to 1 µm. It is also preferred that the topographical features are inclined at a certain angle, such as an angle from 10 to 80°, preferably from 20 to 60°, more 25 preferably from 30 to 50°, most preferably about 40°. Such inclined topographical features are also referred to as slanted or blazed topographical features. It may be also necessary to fill topographical features locally with optical 30 metal oxide layer, either completely or to a certain level, but not to cover adjacent surfaces of the substrate, where no topographical features to be filled are available.
Foreignfiling_text P24-015 - 27 - The substrate is preferably a substrate of an optical device. Preferred substrates are made of inorganic or organic base materials, preferably inorganic base materials. Preferred inorganic base materials contain 5 materials selected from the list consisting of ceramics, glass, fused silica, sapphire, silicon, silicon nitride, quartz, and transparent polymers or resins. The geometry of the substrate is not specifically limited, however, preferred are sheets or wafers. 10 In step (a) of the method, the formulation is applied onto a surface of a substrate or a surface of an underlayer, wherein said surface may be either a surface of a base material of the substrate or a surface of a layer of a material being different from the base material of the substrate, wherein such layer has been formed prior to applying said formulation. 15 In this way, sequences of different layers (layer stacks) can be formed on top of one another. Such layer stacks may be also structured, wherein such structures typically have dimensions on the nanometer scale, at least with respect to diameter, width and/or aspect ratio. 20 Thus, in a preferable embodiment, in step (b), the formulation is at least partly converted on the surface of the substrate to a composite, preferably it is being of a layered composite, by baking it at a temperature from 50 to 400 °C, preferably it is from 80 to 350°C, more preferably from 100 to 25 300°C. In a preferred embodiment of the present invention, said thermal treatment of step (b) is applied at the time in the range from 1 to 60min, preferably 2 to 20 min, more preferably 3 to 10min. 30 In some embodiments, the formulation is at least partly converted on the surface of the substrate to a composite during the thermal treatment
Foreignfiling_text P24-015 - 28 - process of step (b), wherein said composite contains a metal oxide, preferably selected from metal monoxide, dioxide and/or pentoxide; and a metal alkoxide. 5 - Composite In another aspect, the present invention relates to a composite, preferably being a layered composite, preferably said layered composite is an optical layer, derived from the formulation of the present invention. 10 In another aspect, the present invention relates to a composite, preferably being a layered composite, preferably said layered composite is an optical layer, obtained or obtainable by the method of the present invention. In a preferred embodiment of the present invention, the composite 15 comprises at least a metal oxide derived from the 1st and the 2nd metal oxide precursors of the formulation and a 1st and/or a 2nd metal oxide precursor(s) as a non-converted part of the formulation used in step (a) of the method. 20 Thus, in some embodiments of the present invention, the composite comprises, essentially consisting of or consisting of: at least a 1st metal oxide precursor, and a metal oxide derived from said 1st metal oxide precursor, wherein said 1st metal oxide precursor is selected from a metal alkoxide or a metal carboxylate, containing a metal element selected from 25 the group consisting of group 1 elements of the periodic table, group 4 elements, group 5 elements, group 6 elements, group 12 elements, group 14 elements and group 15 elements of the periodic table, and optionally said composite contains a 2nd metal oxide precursor different from the 1st metal oxide precursor, selected from a metal halide, metal alkoxide or a 30 metal carboxylate containing a metal element selected from the group consisting of group 1 elements of the periodic table, group 4 elements,
Foreignfiling_text P24-015 - 29 - group 5 elements, group 6 elements, group 12 elements, group 14 elements and group 15 elements of the periodic table. The details of the metal halide precursor is indicated in the section of 1st 5 metal oxide precursor and 2nd metal oxide precursor above. - Optical device The present invention relates to an optical device comprising the composite of the present invention, and a substrate comprising a patterned surface or 10 an uneven surface having a gap or trench. Preferably a gap or trench of said patterned surface or an uneven surface of the substrate is at least partly filled with said composite. Preferably said substrate is a patterned substrate comprising topographical features on the surface thereof. Preferably said composite fills at least a part of a gap of said topographical 15 features, more preferably said composite fills a trench of the patterned substrate. - Display device Finally, the present invention relates to a display device comprising at least 20 one functional medium configured to modulate a light or configured to emit light; and the composite, or an optical device of the present invention. Examples of said display device is selected from a liquid crystal display (LCD), light emitting diode display (LED display), organic light emitting 25 display (OLED), micro-LED display, quantum dot display (QLED), AR/VR display, plasma (PDP) display and an electroluminescent (ELD) display. The present invention is further illustrated by the examples following herein- after which shall in no way be construed as limiting. The skilled person will 30 acknowledge that various modifications, additions and alternations may be made to the invention without departing from the spirit and scope of the invention as defined in the appended claims.
Foreignfiling_text P24-015 - 30 - Examples - Analytics and measurement methods Ellipsometry is used to determine layer thickness (nm), refractive index (n) 5 (RI) and absorption index (k) of a metal oxide layer. Measurements are performed using an ellipsometer M2000 from J. A. Woolam and three different angles of incidence (65°, 70 ° and 75°). The measurement data is analyzed with software CompleteEase from J. A. Woolam, assuming either full or almost nearly complete transparent behavior above a wavelength of 10 600 nm (at 560nm) and applying B-spline fitting for obtaining refractive indices (n) as well as absorption indices (k). The optical constants are averaged from three to four measured samples each of them providing a different layer thickness either after soft bake or after hard bake or after combined soft and subsequent hard bake. 15 Usually, quartz and/or silicon wafers, both 2 inch in diameter, are used throughout all coating experiments where flat and non-structured carriers for metal oxides are required (e. g. spectroscopic and ellipsometry measurements). 20 SEM images are recorded using either a Mira 3 LMU from Tescan or Sigma 300VP from Carl Zeiss or Supra 35 from Carl Zeiss. Substrate coating, usually wafers, is done using a spin coater (LabSpin 150i) from Suess. The spin coating process using planar substrates is as 25 follows: deposition of 0.5 ml of the coating onto static quartz wafers followed by a spinning interval of 30 seconds at a given spin speed where the acceleration to reach the final spin speed is set to 500 rpm/s². Different layers and coating thicknesses are achieved using either different spin speeds or different coating formulations having different concentrations of 30 the metal oxide precursor or mixtures of different metal oxide precursors. After spin coating, the coated substrates are subjected to thermal cure on a conventional lab hotplate. Usually, however not limited hereto, the coated
Foreignfiling_text P24-015 - 31 - layers are baked at 100 °C to 200 °C for between 1 to 10 minutes. Layer baking is performed using high temperature hotplates from Harry Gestigkeit allowing for reaching temperatures of up to 600 °C. Afore-mentioned conditions and parameters apply to all following experimental examples 5 unless other conditions are explicitly mentioned elsewhere. As an alternative film preparation technique, inkjet printing can be used. The formulations can be filled into single-use cartridges (Dimatix Materials Cartridge with a nominal drop weight of 10 pL) and may be printed using a 10 laboratory scale inkjet printing equipment (Dimatix Materials Printer DMP- 2850 or a Pixdro LP50). The temperature of the printhead and the substrate holder can be set to 30°C. Squares of approximately two by two cm are printed with varying resolutions to obtain different film thicknesses. After printing, the substrates are thermally dried and hardbaked. 15 All substrates, unless otherwise noted, were cleaned by immersion in 2- propanol and ultrasonication for ten minutes; successively immersion in deionized water and ultrasonication for ten minutes and drying on a hot plate at 100°C for 10 minutes. Afterwards the substrates were treated in an 20 oxygen plasma oven (450 watt, 5 minutes). Structured substrates, usually silicon wafers, are used as square-shaped dies with edge lengths of 1.5 cm to 2 cm. The wafer dies are cut and cleaved from a parent wafer, typically having a diameter of 12 inch. The 25 structures are created and arranged in a layer stack composed of SiO2/SiNx deposited onto the wafer surface. Dimensions of the structures (e. g. cross- section width and length of trenches) referred to the architecture of Sematech mask 854. Usually, however not limited hereto, the cross- sectional cleaves perpendicular to trench arrays providing a width of 40 nm 30 to 50 nm are used as trench structures of primary interest to investigate their filling behavior by the wet-chemically coated metal oxide precursors and/or metal oxides received upon thermal conversion of the said metal
Foreignfiling_text P24-015 - 32 - oxide precursors. Besides to aforementioned, cross-sections of arrays of trenches having widths of 100 nm and 150 nm are used to investigate trench filling by metal oxides, too. 5 Structured wafer dies are, unless otherwise mentioned, coated by spin coating. For that purpose, the coating formulation, typically a volume between 0.15 ml to 0.5 ml per die, is pipetted and casted onto wafer’s surface. The formulation is allowed to spread and settle on the surface for one minute followed by a step of distributing and spreading of the 10 formulation over the entire surface of the wafer die at 500 rpm for 30 seconds, followed by a final spin-off step at 2,000 rpm for further 60 seconds. The acceleration of the spin speed is set to 500 rpm/s². The soft bake and hard conditions of structured wafer dies is chosen similar or identical to those already mentioned for flat substrates. 15 All chemicals for synthesis described are purchased from Sigma Aldrich and used without further purification, unless differently mentioned elsewhere.98 % anhydrous SnCl2 is used for the experiments described successively. 20 Working example 1: Preparation of formulation 1 Formulation 1: Nb(OEt)5 (4.15wt%), SnCl22H2O (5wt%) nominal solid content dissolved in 90wt% PGME is made. A clear, transparent and colorless solution is achieved which became filtered using 0.2 µm syringe 25 filter to remove any kind of particles and other suspended materials. Working examples 2 to 8: Preparation of formulations 2 to 8 Formulations 2-8: Formulations 2 to 8 are made in the same manner as disclosed in working example 1 above except for that the materials 30 mentioned in table 1 is used with the described amount instead of the materials used in working example 1.
Foreignfiling_text P24-015 - 33 - Table 1: 5 10 Material 1: 1st metal oxide precursor Material 2: 2nd metal oxide precursor 15 Molar ratio: Material 1: Material 2 Solvent ratio = Solvent 1 : Solvent 2 As disclosed in table 1, Formulations 2 to 8 contain two different solvents (Solvent 1 and Solvent 2) while Formulation 1 contains only 1 solvent. 20 It is said that obtaining a good solubility with high solid content of metal oxide precursor, such as Nb containing metal oxide precursor, in a formulation is challenging. The results show that by using two different solvents, improved solubility of high solid content of metal oxide precursor(s) in a formulation may be realized. 25 Working examples 9: forming a layer Sample 1 (a layer made from Formulation 1, baking temperature 150°C/5min) is prepared by the following process. Formulation 1 from working example 1 (W.E.1) is spin coated with 2,000 30 rpm onto an O2 plasma pretreated Si3N4/Si substrate having 150nm width trenches on the surface. Then the coated layer is baked at 150°C for 5min. Finally, Sample 1 is obtained.
Foreignfiling_text P24-015 - 34 - Working examples 10: forming layers Sample 2 (a layer made from Formulation 1, baking temperature 200°C/5min) and Sample 3 (a layer made from Formulation 1, baking 5 temperature 250°C/5min) are made in the same manner as described in working example 9 above except for that the different baking temperature conditions (200°C/5min for Sample 2, 250°C/5min for Sample 3) are applied. 10 Working examples 11: RI value measurement and observation of Gap filing property Obtained samples 1 to 3 are measured with the ellipsometry and following refractive index values (RI values) are obtained. 15 As indicated above, obtained RI values are exceptionally high, especially given the lower baking temperatures. It is considered as important for AR/VR devices or other applications obtaining such high RI value layer 20 without applying high (>250°C) baking temperature. In this experiment, even at 200°C and at 150°C baking, high RI value are obtained. Working examples 12: forming layers & observation of gap filing property Sample 4 (a layer made from Formulation 1, baking temperature 25 150°C/5min, 100nm trench width) is obtained in the same manner as described in working example 9 except for that “an O2 plasma pretreated Si3N4/Si substrate having 100nm width trenches on the surface” is used. In the same manner, Sample 5 (a layer made from Formulation 1, baking temperature 200°C/5min, 100nm trench width), Sample 6((a layer made 30 from Formulation 1, baking temperature 250°C/5min, 100nm trench width) are obtained.
Foreignfiling_text P24-015 - 35 - Gap filing property of the Formulation 1 for an O2 plasma pretreated Si3N4/Si substrate having 100nm width trenches on the surface, is also highly positive and shows good results. Fig.7a is a SEM image of Sample 1 (Formulation 1, 150°C/5min, 150nm 5 trench width) and Fig.7b is a SEM image of Sample 4 (Formulation 1, 150°C/5min, 100nm trench width). Working examples 13: forming layers & RI value measurement Sample 7 (a layer made from Formulation 2, baking temperature 10 150°C/5min), Sample 8 (a layer made from Formulation 2, baking temperature 200°C/5min), Sample 9 (a layer made from Formulation 2, baking temperature 250°C/5min), Sample 10 (a layer made from Formulation 3, baking temperature 150°C/5min), Sample 11 (a layer made from Formulation 3, baking temperature 200°C/5min), Sample 12 (a layer 15 made from Formulation 3, baking temperature 250°C/5min), Sample 13 (a layer made from Formulation 4, baking temperature 150°C/5min), Sample 14 (a layer made from Formulation 4, baking temperature 200°C/5min), Sample 15 (a layer made from Formulation 4, baking temperature 250°C/5min), Sample 16 (a layer made from Formulation 5, baking 20 temperature 150°C/5min), Sample 17 (a layer made from Formulation 5, baking temperature 200°C/5min), Sample 18 (a layer made from Formulation 5, baking temperature 250°C/5min), Sample 19 (a layer made from Formulation 6, baking temperature 150°C/5min), Sample 20 (a layer made from Formulation 6, baking temperature 200°C/5min), Sample 21 (a 25 layer made from Formulation 6, baking temperature 250°C/5min), Sample 22 (a layer made from Formulation 7, baking temperature 150°C/5min), Sample 23 (a layer made from Formulation 7, baking temperature 200°C/5min), Sample 24 (a layer made from Formulation 7, baking temperature 250°C/5min), Sample 25 (a layer made from Formulation 8, 30 baking temperature 150°C/5min), Sample 26 (a layer made from Formulation 8, baking temperature 200°C/5min) and Sample 27 (a layer made from Formulation 8, baking temperature 250°C/5min) are made in the
Foreignfiling_text P24-015 - 36 - same manner as described in working example 9 above except for that the different baking temperature conditions and formulations as mentioned in table 2 are used. Table 2: 5 10 15 20 25 As indicated in Table 2, obtained RI values are exceptionally high, especially given the lower baking temperatures. It is considered as important for AR/VR devices or other applications obtaining such high RI value layer without applying high (>250°C) baking temperature. In this experiment, even at 200°C and at 150°C baking, high RI value are 30 obtained. Working examples 14: forming layers & layer uniformity analysis
Foreignfiling_text P24-015 - 37 - Sample 28 (a layer made from Formulation 5, baking temperature 100°C/5min) is prepared by the following process. Formulation 5 from working example 5 (W.E.5) is spin coated with 2,000 rpm onto an O2 plasma pretreated plane quartz wafer. Then the coated 5 layer is baked at 150°C for 5min. Finally, Sample 1 is obtained. Then, Samples 29 to 39 are fabricated in the same manner as described on Sample 28 except for that different baking conditions and formulation as described in Table 3 are used. 10 15 20 The results show that formulation containing two different solvents realize 25 improved layer uniformity and also lower optical absorption in visible light wavelength range. 30