SUBSTRATE AND METHOD FOR MODIFYING AT LEAST ONE REGION OF A SURFACE OR A PORTION OF A SUBSTRATE
20230102394 · 2023-03-30
Assignee
Inventors
- Clemens Ottermann (Hattersheim, DE)
- Frederick Bachhuber (Mainz, DE)
- Stefan Weidlich (Mainz-Kastel, DE)
Cpc classification
G02B6/1223
PHYSICS
International classification
Abstract
A method for physically modifying at least one of at least one region of a surface of a substrate and at least one portion of the substrate, the substrate comprising a multicomponent glass, the method comprising the steps of: providing an apparatus and the substrate, the apparatus including a radiation source configured for generating a particle beam; feeding the substrate to the apparatus and applying a vacuum; modifying at least one of the at least one region of the surface of the substrate and the at least one portion of the substrate by an exposure to the particle beam.
Claims
1. A method for physically modifying at least one of at least one region of a surface of a substrate and at least one portion of the substrate, the substrate comprising a multicomponent glass, the method comprising the steps of: providing an apparatus and the substrate, the apparatus including a radiation source configured for generating a particle beam; feeding the substrate to the apparatus and applying a vacuum; modifying at least one of the at least one region of the surface of the substrate and the at least one portion of the substrate by an exposure to the particle beam.
2. The method according to claim 1, wherein the substrate comprises a plurality of oxides of at least two different cations, the substrate being an optical glass, an optical ceramic, or a glass-ceramic.
3. The method according to claim 2, wherein the substrate comprises at least one optical crown glass or at least one optical flint glass, selected from the group including at least one of silicon-, boron-, aluminum-, phosphorus-, fluorine-, lanthanum-, titanium-, barium- and niobium-containing crown or flint glasses.
4. The method according to claim 3, wherein the substrate comprises the following constituents (in wt % based on oxide): TABLE-US-00011 Constituent Amount (wt %) SiO.sub.2 0-80 P.sub.2O.sub.5 0-40 Al.sub.2O.sub.3 0-25 B.sub.2O.sub.3 0-55 Li.sub.2O 0-10 Na.sub.2O 0-25 K.sub.2O 0-25 MgO 0-10 CaO 0-30 SrO 0-25 BaO 0-55 ZnO 0-30 La.sub.2O.sub.3 0-55 Gd.sub.2O.sub.3 0-20 Y.sub.2O.sub.3 0-20 ZrO.sub.2 0-20 TiO.sub.2 0-35 Ta.sub.2O.sub.5 0-30 Nb.sub.2O.sub.5 0-55 WO.sub.3 0-10 GeO.sub.2 0-20 Bi.sub.2O.sub.3 0-65 PbO 0-80 F 0-45.
5. The method according to claim 1, wherein a refractive index n.sub.d of the substrate, based on a wavelength of 587.6 nm, is in a range from 1.45 to 2.45, in a range from 1.50 to 2.40, in a range from 1.55 to 2.35, in a range from 1.60 to 2.30, in a range from 1.65 to 2.25, or in a range from 1.70 to 2.20.
6. The method according to claim 1, wherein the substrate has an internal transmission of at least 80%, at least 85%, at least 90%, or at least 95%, measured at a wavelength of 450 nm and a sample thickness of 10 mm.
7. The method according to claim 1, wherein before the step of providing, the substrate is separated off from a monolithic bar or block, the method further comprising the steps of: drilling a cylinder from the monolithic bar or block; separating off the substrate from the cylinder; grinding a plurality of edges of the substrate to a desired wafer diameter; introducing faceting of the plurality of edges; applying a positional mark; fine-working at least one surface of the substrate.
8. The method according to claim 1, wherein the substrate has a thickness of between 0.2 mm and 2 mm, between 0.3 mm and 1 mm, or between 0.4 mm and 0.75 mm, the thickness of the substrate being smaller than a lateral extent of the substrate.
9. The method according to claim 1, wherein the substrate is rotationally symmetrical and has a diameter which is between 0.7 cm and 50 cm or between 3 cm and 45 cm, and corresponds to a diameter of a 2-inch wafer or a 50.8 mm wafer, a 3-inch wafer or a 76.2 mm wafer, a 4-inch wafer or a 100 mm wafer, a 5-inch wafer or a 125 mm wafer, a 6-inch wafer or a 150 mm wafer, a 8-inch wafer or a 200 mm wafer, a 12-inch wafer or a 300 mm wafer, or an 18-inch wafer or a 450 mm wafer.
10. The method according to claim 1, wherein the substrate or a plurality of surfaces delimiting the substrate in a lateral direction fulfill at least one of the following characteristics: Total Thickness Variation (TTV): <=10 μm; Local Slope: <=1 arcmin; Warp: <=100 μm; Bow: −100 μm<=Bow<=100 μm; Roughness: R.sub.q<=10 μm.
11. The method according to claim 1, wherein the substrate comprises a first surface and a second surface opposite thereto, the first surface and the second surface being planar or at least one of the first surface and the second surface being concave or convex.
12. The method according to claim 1, wherein the step of modifying comprises polishing the at least one region of the surface of the substrate or an entire surface of the substrate with the particle beam, the exposure to the particle beam causing an atomization and an ablation of a material from the surface.
13. The method according to claim 12, wherein the substrate comprises at least one modified region which fulfills at least one of the following characteristics: Total Thickness Variation (TTV): <=1 μm, <=0.75 μm, <=0.5 μm, <=0.4 μm, <=0.3 μm, or <=0.2 μm; Local Slope: <=0.3 arcmin, <=0.16 arcmin, <=0.13 arcmin, or <=0.10 arcmin; Warp: <=100 μm, <=70 μm, or <=50 μm; Bow: −50 μm<=Bow<=50 μm; Roughness: R.sub.q<=1 μm, <=100 nm, or <=10 nm.
14. The method according to claim 1, wherein the step of modifying at least one of: reduces an existing thickness difference; and creates a predetermined thickness distribution.
15. The method according to claim 1, wherein the method further includes measuring a thickness distribution or a thickness profile of the substrate before the step of modifying in order to obtain a plurality of specifications for the step of modifying, the measuring taking place by way of at least one method of interferometry or by way of an interferometry of a plurality of planar wavefronts.
16. The method according to claim 1, wherein, before the step of modifying, a supporting layer is applied at least to a plurality of the region of the surface of the substrate or the at least one portion of the substrate that is/are to be modified, the supporting layer being a carbon layer or a graphite layer.
17. The method according to claim 1, wherein the step of modifying comprises generating a microgroove or microgap for subsequent parting.
18. The method according to claim 1, wherein the step of modifying comprises working an edge of the substrate.
19. The method according to claim 1, wherein the step of modifying comprises structuring or introducing a grating or a pattern on the at least one region of the surface of the substrate with the particle beam.
20. The method according to claim 19, wherein the particle beam is a focused ion beam, which, for the step of modifying, is guided by way of a plurality of deflection units over the at least one region of the surface of the substrate or the at least one portion of the substrate.
21. A substrate, comprising: a multicomponent glass, which is produced or configured for being produced by a method for physically modifying at least one of at least one region of a surface of the substrate and at least one portion of the substrate, the method comprising the steps of: providing an apparatus and the substrate, the apparatus including a radiation source configured for generating a particle beam; feeding the substrate to the apparatus and applying a vacuum; modifying at least one of the at least one region of the surface of the substrate and the at least one portion of the substrate by an exposure to the particle beam.
22. The substrate according to claim 21, wherein at least one surface of the substrate possesses a near-surface marginal region having a depth of up to 500 nm, of at least 40 nm to 400 nm, the near-surface marginal region being free or largely free of an accumulation of cerium oxide or potassium.
23. The substrate according to claim 21, wherein at least one surface of the substrate has fewer than 100, fewer than 50, fewer than 20, fewer than 10, fewer than 5, or fewer than 2 scratches in a region of 2 μm x 2 μm, with a respective one of the scratches having: a length in a range from 100 nm to 15,000 nm, from 250 nm to 10,000 nm, from 300 to 5,000 nm, or from 400 to 2,800 nm; a depth of 0.5 to 100 nm, 1 to 50 nm, or 10 to 25 nm; and a width of 0.5 to 50 nm, 1 to 25 nm, and 2 to 10 nm.
24. A method of using a substrate, the method comprising the steps of: providing that the substrate includes a multicomponent glass, wherein the multicomponent glass is produced or configured for being produced by a method for physically modifying at least one of at least one region of a surface of the substrate and at least one portion of the substrate, the method comprising the steps of: providing an apparatus and the substrate, the apparatus including a radiation source configured for generating a particle beam; feeding the substrate to the apparatus and applying a vacuum; modifying at least one of the at least one region of the surface of the substrate and the at least one portion of the substrate by an exposure to the particle beam. using the substrate for at least one application in a field of augmented reality or as a cover for at least one microelectronic system.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0193] The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
[0194]
[0195]
[0196]
[0197] Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrate at least one embodiment of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.
DETAILED DESCRIPTION OF THE INVENTION
[0198] optional In the detailed description below of optional embodiments, identical reference symbols for the sake of clarity designate substantially identical parts in or on these embodiments. For better illustration of the present invention, however, the optional embodiments represented in the figures are not always drawn to scale.
[0199]
[0200] The apparatus 10 is designed for implementing a method for modifying at least a region of a surface and/or a portion of the substrate 20, the substrate 20 including a multicomponent glass. Drawn on a purely illustrative basis in
[0201] The apparatus 10 includes an ion source as radiation source 11, which is used to generate ions. In the exemplary embodiment the assumption is made that these are positively charged ions, more particularly of argon. The particle beam 12 is directed as a focused ion beam in operation onto the substrate 20 mounted in the apparatus 10, and a vacuum is applied, optionally a high vacuum. A corresponding chamber (not represented) is provided for this purpose. In the operation of the apparatus 10, the ions are accelerated in the direction onto the substrate 20. On impingement on the surface 21 of the substrate 20 being worked, there is a transfer of impulse from the ions to the substrate 20, and material is atomized and ablated from the surface 21 by exposure to the particle beam 12. As a result of this, a region of the surface 21 and/or a portion of the substrate 20 are/is modified by exposure to the particle beam 12, and a modified region 22 is produced.
[0202] The particle beam 12 may be guided over a region or portion of the substrate 20 by way of corresponding deflection units (not represented), in order to modify that region or portion accordingly. The deflection units are equipped such that any desired point on the substrate 20 can be reached.
[0203] The apparatus 10 includes suitable computer-assisted devices 14 for controlling the particle beam, allowing the particle beam 12 to be guided over the substrate 20 according to mandatable programs or parameters. This may also take place more than once, in order to ablate more material, for instance or to ablate material to a different depth. The controlling of the particle beam 12 here may relate not only to the guiding of the particle beam 12 over the substrate 20, but also, instead, to the setting of performance parameters of the particle beam, examples being the intensity, the duration, the focusing, or the angle at which the particle beam 12 impinges on the substrate 20 at the corresponding point.
[0204] The substrate 20 here includes a multicomponent glass. This means that the substrate 20 includes at least oxides of at least two different cations.
[0205] In the case of the embodiment depicted, the multicomponent glass is an optical glass. Optical glass in the sense of the invention refers to glasses suitable for optical applications, especially optical crown glasses and flint glasses. These may be selected from the group encompassing silicon-, boron-, aluminum-, phosphorus-, fluorine-, lanthanum-, titanium-, barium- and/or niobium-containing crown or flint glasses.
[0206] Particularly suitable glasses for the substrate 20 are glasses which include the following constituents (in wt % based on oxide):
TABLE-US-00006 Constituent Amount (wt %) SiO.sub.2 0-80 P.sub.2O.sub.5 0-40 Al.sub.2O.sub.3 0-25 B.sub.2O.sub.3 0-55 Li.sub.2O 0-10 Na.sub.2O 0-25 K.sub.2O 0-25 MgO 0-10 CaO 0-30 SrO 0-25 BaO 0-55 ZnO 0-30 La.sub.2O.sub.3 0-55 Gd.sub.2O.sub.3 0-20 Y.sub.2O.sub.3 0-20 ZrO.sub.2 0-20 TiO.sub.2 0-35 Ta.sub.2O.sub.5 0-30 Nb.sub.2O.sub.5 0-55 WO.sub.3 0-10 GeO.sub.2 0-20 Bi.sub.2O.sub.3 0-65 PbO 0-80 F 0-45
[0207] Optional optical glasses for the substrate 20 are glasses which include or consist of the following constituents (in wt % based on oxide):
TABLE-US-00007 SiO.sub.2 0-80 P.sub.2O.sub.5 0-30 Al.sub.2O.sub.3 0-15 B.sub.2O.sub.3 0-55 Li.sub.2O 0-10 Na.sub.2O 0-25 K.sub.2O 0-25 MgO 0-5 CaO 0-30 SrO 0-10 BaO 0-55 ZnO 0-30 La.sub.2O.sub.3 0-55 Gd.sub.2O.sub.3 0-20 Y.sub.2O.sub.3 0-20 ZrO.sub.2 0-20 TiO.sub.2 0-35 Ta.sub.2O.sub.5 0-30 Nb.sub.2O.sub.5 0-55 WO.sub.3 0-10 GeO.sub.2 substantially free from it Bi.sub.2O.sub.3 substantially free from it PbO 0-70 F 0-25
[0208] Optional optical glasses for the substrate 20 are glasses which include or consist of the following constituents (in wt % based on oxide):
TABLE-US-00008 SiO.sub.2 0-80 P.sub.2O.sub.5 0-5 Al.sub.2O.sub.3 0-10 B.sub.2O.sub.3 0-45 Li.sub.2O 0-10 Na.sub.2O 0-20 K.sub.2O 0-20 MgO 0-5 CaO 0-30 SrO 0-10 BaO 0-55 ZnO 0-30 La.sub.2O.sub.3 0-55 Gd.sub.2O.sub.3 0-20 Y.sub.2O.sub.3 0-20 ZrO.sub.2 0-20 TiO.sub.2 0-35 Ta.sub.2O.sub.5 0-30 Nb.sub.2O.sub.5 0-35 WO.sub.3 0-10 GeO.sub.2 substantially free from it Bi.sub.2O.sub.3 substantially free from it PbO substantially free from it F 0-5
[0209] Optional optical glasses for the substrate 20 are glasses which include or consist of the following constituents (in wt % based on oxide):
TABLE-US-00009 SiO.sub.2 0-60 P.sub.2O.sub.5 0-2 Al.sub.2O.sub.3 0-5 B.sub.2O.sub.3 0-45 Li.sub.2O 0-10 Na.sub.2O 0-10 K.sub.2O 0-10 MgO 0-5 CaO 0-30 SrO 0-10 BaO 0-30 ZnO 0-30 La.sub.2O.sub.3 0-55 Gd.sub.2O.sub.3 0-20 Y.sub.2O.sub.3 0-20 ZrO.sub.2 0-15 TiO.sub.2 0-20 Ta.sub.2O.sub.5 0-25 Nb.sub.2O.sub.5 0-20 WO.sub.3 0-5 GeO.sub.2 substantially free from it Bi.sub.2O.sub.3 substantially free from it PbO substantially free from it F substantially free from it
[0210] Optional optical glasses for the substrate 20 are glasses which include or consist of the following constituents (in wt % based on oxide):
TABLE-US-00010 SiO.sub.2 0-15 P.sub.2O.sub.5 substantially free from it Al.sub.2O.sub.3 substantially free from it B.sub.2O.sub.3 0-45 Li.sub.2O substantially free from it Na.sub.2O substantially free from it K.sub.2O substantially free from it MgO substantially free from it CaO 0-15 SrO 0-5 BaO 0-10 ZnO 0-30 La.sub.2O.sub.3 0-55 Gd.sub.2O.sub.3 0-20 Y.sub.2O.sub.3 0-20 ZrO.sub.2 0-10 TiO.sub.2 0-15 Ta.sub.2O.sub.5 0-10 Nb.sub.2O.sub.5 0-15 WO.sub.3 0-5 GeO.sub.2 substantially free from it Bi.sub.2O.sub.3 substantially free from it PbO substantially free from it F substantially free from it
[0211] The glasses may include refining agents, such as Sb.sub.2O.sub.3 and/or As.sub.2O.sub.3, for example, in small amounts, in amounts for example of in each case less than 0.1 wt %, less than 0.03 wt % or less than 0.01 wt %.
[0212] The above glass compositions may optionally include additions of coloring oxides, such as Nd.sub.2O.sub.3, Fe.sub.2O.sub.3, CoO, NiO, V.sub.2O.sub.5, MnO.sub.2, CuO, CeO.sub.2, Cr.sub.2O.sub.3, and/or rare earth oxides, for example, in amounts of—in each case individual or in total—0-15 wt %. Optional variants are free from coloring oxides. Particularly optional optical glasses of the substrate 20 are free from Fe.sub.2O.sub.3.
[0213] The fraction of platinum is optionally especially low, since platinum lowers the transmission of the optical glass to a particular degree. The fraction of platinum is optionally less than 5 ppm, optionally less than 3 ppm, optionally less than 1 ppm, optionally less than 50 ppb, optionally less than 20 ppb.
[0214] In a further, likewise optional embodiment, the multicomponent glass of the substrate 20 is a glass-ceramic. Representing a particularly suitable material for the substrate 20 are zero-expansion LAS glass-ceramics, such as, for example, the glass-ceramic material ZERODUR® from Schott AG, Mainz, Germany.
[0215] In a yet further, likewise optional embodiment, the multicomponent glass is an optical ceramic.
[0216] The substrate 20 here has a refractive index n.sub.d, based on a wavelength of 587.6 nm, in a range from 1.45 to 2.45. The refractive index n.sub.d may optionally be situated, furthermore, in a range from 1.50 to 2.40, optionally in a range from 1.55 to 2.35, optionally in a range from 1.60 to 2.30, optionally in a range from 1.65 to 2.25, optionally in a range from 1.70 to 2.20.
[0217] Moreover, according to one optional embodiment, the substrate 20 has an internal transmission of at least 80%, more particularly at least 85% or at least 90%, very optionally at least 95%, measured at a wavelength of 450 nm and a sample thickness of 10 mm.
[0218] Furthermore, according to another optional embodiment, the substrate 20 is distinguished by a high mechanical resistance or high hardness. The substrate 20 according to the invention optionally has a Knoop hardness H.sub.k of 2 GPa to 10 GPa, optionally of 2.5 GPa to 9.5 GPa, optionally of 3 GPa to 9 GPa, optionally of 3.5 GPa to 8.5 GPa, optionally of 4 to 8 GPa.
[0219] The optical and mechanical properties stated above for the substrate 20 are valid both for the substrate in the original state and for the modified regions 22 or substrates 20 modified accordingly.
[0220] In contrast to methods for the working of silicon wafers, for example, the method of the invention advantageously enables the working of hard, transparent and/or high-index substrates composed of glass, glass-ceramic or optical ceramic.
[0221] In the exemplary embodiment the substrate 20 includes a diffractive optical element, with the method of the invention enabling the modification at least of regions of the surface or portions.
[0222] In certain embodiments the substrates 20 may also include wafers, examples being glass wafers, glass-ceramic wafers or optical-ceramic wafers. In the exemplary embodiment of
[0223] Wafers of these kinds composed of high-transparency, high-index glass, glass-ceramic or optical ceramic may be used very effectively for—for example—imaging optical systems in the field of augmented reality (AR).
[0224]
[0225] The glass wafer 30 is separated from a monolithic bar or block including optical glass. For this purpose, raw materials in accordance with one of the compositions stated above can be melted in a glass-melting facility and, in the form of molten glass, cast into bars or blocks.
[0226] Depending on the material selected for the substrate 20, other production methods are also conceivable and possible—for example, the downdraw method, the overflow fusion method, redrawing, or else floating. In the case of optical ceramics it is also possible, for example, to provide a monocrystalline block, also referred to as an ingot.
[0227] Subsequently the following machining steps may be performed: [0228] drilling an oversize cylinder from the bar or block; [0229] separating off the substrates 20 from the cylinder; [0230] grinding the edges to the desired wafer diameter; [0231] introducing faceting of the edges; [0232] applying a positional mark 24; [0233] optionally fine-working at least one surface of the substrate 20.
[0234] Separation from the cylinder may be accomplished by sawing, using wire saws, for example, with typically an oversize being provided likewise in the thickness.
[0235] The fine working of at least one of the surfaces 21 may be accomplished in one or more refinement steps, including precision polishing or lapping, in order to attain the corresponding properties and to bring the substrate 20 as close as possible to the required specifications.
[0236] In another embodiment no fine-working is carried out after the separating. This has the advantage that the substrate 20 does not need to come into contact with polishing agent if, following singulation, there is only modifying by way of a particle beam.
[0237] The application of a positional mark 24, such as a notch or score, for example, may facilitate subsequent ongoing processing of the substrate 20, when, for example, further components are to be divided off from a substrate 20. The positional mark 24 enables utility regions 23 to be specified in relation to the positional mark 24 or to an orientation point on or in the substrate, even in the case of rotationally symmetric substrates 20. The marking may be applied in or on the substrate 20 by way of a laser beam, for example.
[0238] Utility regions 23 can therefore be defined for subsequent separation of parts such as, for example, the component 31 from the substrate 20, and this may increase the yield, for instance.
[0239]
[0240] Presently it is also possible to forgo subsequent measurements, on the part of an operator carrying out further processing of the substrates, for instance, since the utility regions 23 are identified by measurements and specified and together with the positional mark 24 there is an individualization of the substrate 20 with recording of information about the utility regions 23. This information relates, for instance, to the specific position and extent of the utility regions 23 in relation to the positional mark 24.
[0241] For this purpose, as well as the positional mark 24, the substrate 20 has an identity mark 25, which enables unambiguous identification of the respective substrate. The identity mark 25 enables unambiguous identification of the respective substrate 20.
[0242] The substrate 20 has a thickness of between 0.2 mm and 2 mm, optionally between 0.3 mm and 1 mm, also optionally between 0.4 mm and 0.75 mm. The thickness of the substrate 20 in this case is smaller than the lateral extent of the substrate 20.
[0243] Where separated components 31 are to be modified, this component 31, for example an eyepiece or a precursor of an eyepiece, may already have the desired outer contour. The outer contour in this case may encompass any desired geometrical shape, examples being linear or curved portions or else corners, including, in particular, irregular outer contours. Such components 31 may possess comparatively small dimensions, in a range, for example, starting from about 2 mm×2 mm, with the minimum and maximum sizes being limited by the apparatus 10 and the accommodation facilities or mounts 13.
[0244] In the embodiment of
[0245] The substrate 20 in the exemplary embodiment is provided as a glass wafer 30 for uses in the field of augmented reality. For this purpose, for the substrate 20 or for the surfaces 21 delimiting the substrate 20 in a lateral direction, at least one of the following properties or characteristics is fulfilled: [0246] Total Thickness Variation (TTV): <=10 μm; [0247] Local Slope: <=1 arcmin; [0248] Warp: <=100 μm; [0249] Bow: −100 μm<=Bow<=100 μm; [0250] Roughness: R.sub.q<=10 μm.
[0251] These properties refer accordingly to the substrate 20 or to surfaces 21 of the substrate 20 prior to modifying in accordance with the invention. The above-stated characteristics have proven to be favorable for the modifying, although of course substrates 20 may also be modified that deviate from this in one or more characteristics.
[0252] The substrate 20 is characterized in a lateral direction by a first surface 21 and a second, opposite surface, with these two surfaces 21 being parallel to one another in the exemplary embodiment. It is, however, also possible for at least one surface 21 to be concave or convex. In principle other topologies of the surface 21 are also possible and conceivable. This itself is a major advantage of the invention.
[0253] A surface 21 and/or a portion of a substrate 20 may be modified for various purposes.
[0254] Hence, in one aspect of the invention, the intention through modifying a surface 21 and/or a portion of the substrate 20 is to remove material from the surface, in order, in the region thus modified, to reduce the thickness and/or to improve the surface quality and/or to attain compliance with characteristics in accordance with the mandated specification.
[0255] For this purpose, the surface 21 or a region of the surface 21 or a portion of the substrate is exposed to the particle beam, with the exposure enabling atomization and ablation of material from the surface. This operation is also referred to as polishing or “Trimming”. In
[0256] The thickness of the substrate 20 can be reduced in the modified region 22 in this way, and/or the surface quality can be improved. It is, however, also possible to improve one or all of the aforementioned characteristics of the substrate 20, embracing the Total Thickness Variation, the Local Slope, the Warp, the Bow and/or the Roughness.
[0257] On the basis of the above-stated manifestations of the characteristics, therefore, it is possible to provide a substrate 20 which includes at least one modified region 22, and where at least one of the following characteristics is fulfilled for at least the modified region 22: [0258] Total Thickness Variation (TTV): <=1 μm or <=0.75 μm or <=0.5 μm, optionally <=0.4 μm, more optionally <=0.3 μm, or even <=0.2 μm; [0259] Local Slope: <=0.3 arcmin, <=0.16 arcmin, optionally <=0.13 arcmin, more optionally <=0.10 arcmin; [0260] Warp: <=100 μm, optionally <=70 μm, more optionally <=50 μm; [0261] Bow: −50 μm<=Bow<=50 μm; [0262] Roughness: R.sub.q<=1 μm, optionally <=100 nm, more optionally <=10 nm.
[0263] The area of the modified region in this case may be very small—for example, about 2 mm×2 mm. It may, however, of course also be much larger or else may include the entire surface 21 of the substrate 20. The above-stated characteristics may be based, for example, on a rotationally symmetric substrate 20 with the size of a 6-inch wafer as depicted or of an 8-inch wafer.
[0264] For example, then, according to one embodiment of the invention, the entire surface 21 of the substrate can be modified, in order to reduce the overall thickness, or in order to ablate residues of polishing agent and restore the original optical properties of the substrate 20.
[0265] This may be very advantageous, since residues of polishing agent can penetrate into the surface 21 of the substrate 20 and in some circumstances can alter the optical properties, in terms of the refractive index, for instance. In the field of augmented reality applications in particular, however, even very small deviations in refractive index may result in altered optical properties in subsequent use, and in instances of distortion, for example.
[0266] The substrate 20 in the exemplary embodiment includes two planar or approximately planar surfaces 21. At least one surface 21 may alternatively be convex or concave. The surfaces, however, may of course also have other topologies.
[0267] Through the modifying it is possible, for example, to reduce an existing thickness difference, as for example by 1%, by 5%, or by 10%, by 20% or even more, such as by 30%, for example. This may be useful when the precision polishing as part of the production of the substrate has introduced an unwanted thickness distribution, with the marginal regions, for example, having been ablated to a greater extent than regions of the substrate 20 near the center, and the intention is to produce a maximum uniformity of thickness of the surfaces 21.
[0268] In a further embodiment of the invention, however, it is also possible to impress a particular distribution on the thickness distribution of the substrate 20 by the modifying, or to alter an existing thickness distribution.
[0269] For this purpose, the method of the invention additionally and advantageously includes the measuring of the substrate 20 or of the thickness distribution, or the profile of the thickness distribution, of the substrate 20 prior to the modifying, in order to ascertain the desired characteristics.
[0270] The characteristics obtained can be calibrated against the required specifications, and, from the deviation or difference in the measured characteristics relative to the required characteristics, target mandates can be ascertained for the modifying and can be transmitted to the controller 14 of the apparatus 10 for generating a particle beam 12. In this way, for example, the thickness distribution of the substrate 20 can be measured prior to the modifying and compared with a target profile.
[0271] The method of the invention, particularly in connection with the positional mark 24 of the substrate 20 and with the measurement, affords a further major advantage. Hence, on the basis of the measured characteristics and of a comparison with required specifications, it is possible to ascertain and specify accordingly the possible utility regions 23 on the substrate. Where, for example, individual components 31, for subsequent use as eyepieces, for instance, are to be separated off from the substrate, the yield can be optimized by identifying those utility regions 23 of the substrate 20 that come closest to the eyepiece specification. In this way, the number of components 31 obtainable from a substrate 20 can be optimized, and/or those regions or portions of the substrate which are subsequently modified in accordance with the invention can be specified in a targeted way.
[0272] On the one hand this makes it possible to forgo the cost and inconvenience of modifying, since prior to the modifying it is possible to deliberately select and specify those regions on the surface 21 of the substrate 20 that are to be processed. On the other hand, the yield can also be boosted through the possibility of optimizing the number and size of components to be separated per substrate, as a function of the characteristics ascertained.
[0273] In one embodiment of the invention, prior to the modifying, provision may be made for a supporting layer to be applied at least to those regions of the surface 21 that are to be modified, or at least to the portion of the substrate 20 that is to be modified, in order to avoid possible discharges of the surface. This layer may be a carbon layer or graphite layer, for example.
[0274] The present invention also provides for the modifying to include the production of a microgroove or microgap on the surface of the substrate. This microgroove or microgap may serve as preparation for a later parting, such as in order to separate eyepiece components from the substrate. This microgap 26 may be introduced, for example, along the delimitation, represented by dashes, of the utility regions 23 on the surface 21 of the substrate 20, by way of modifying in accordance with the invention.
[0275] The present invention also provides for the modifying to include the working of an edge 27 of a substrate 20. In this case, material can be ablated from the edge 27 of the substrate 20, in regions in which there are microcracks. The microcracks can enlarge, under mechanical loads, for instance, and can lead to uncontrolled breaking of the substrate. The invention enables the working of edges such that, through ablation of material, the microcracks are ablated as well and an edge 27 is produced which is free or virtually free from microcracks. Given that the microcracks are generally fairly small, ablation in an order of magnitude of just a few 100 μm may significantly increase the fracture resistance.
[0276] In one development of the invention, the intention is to guide the particle beam 12 not only perpendicularly to the surface or the edge, but instead at an angle. In this way the edge as well can be formed in a predetermined angle.
[0277] An angle can also be achieved by exposing regions of the edge 27 to the particle beam 12 for different lengths of time or a different number of times.
[0278] It is also possible to alter the transition from surface to the side wall of the substrate in accordance with a desired topology by the modifying, in order, for example, to produce a rounding or a rounded edge.
[0279] The present invention also provides that the modifying includes the structuring or the introduction of a grating or pattern on at least one region of the surface of the substrate with the particle beam. The grating here may be very fine in form, with depths and widths of the trenches produced in a range of a few micrometers, for instance.
[0280] As is evident to the skilled person, the above-stated embodiments of the modifying of a surface and/or of a portion of a substrate may also be combined with one another.
[0281] Hence it is possible first of all, for example, to specify the utility regions 23 on the surface 21 of the substrate 20 and to modify these regions of the substrate 20 surface 21 in order to comply there with the required specifications. An identity mark 25 can then be introduced. Lastly, in a further procedure, the microgrooves 26 can be introduced in preparation for later singulation. The invention affords the major advantage that there is no need for this purpose to take the substrate 20 out of the apparatus 10.
[0282] This not only reduces the time involved, but may also lead to better quality, as the substrates 20 can react very sensitively to impacts or mechanical effects, and, moreover, removal also carries with it the risk of the substrate 20 being exposed to temperature changes, which especially in the case of very thin substrates can result in unwanted deformation. If the substrate 20 then has to be inserted again and mounted in an apparatus for a further operating step, this process itself may mean that it is no longer possible to comply with specifications.
[0283] In one development of the invention, in the method, a layer may be applied prior to the modifying, optionally a protective layer, such as a photoresist layer or masking layer, for example, in which case regions of the surface or portions of the substrate that are not to be modified may be covered.
[0284] Embraced by the invention as well, in a further aspect of the invention, is a substrate 20, the substrate 20 including a multicomponent glass, and the substrate being produced or producible with a method for modifying at least regions of a surface as set out above.
[0285] A substrate 20 modified in accordance with the invention here satisfies the manifestations set out above, in terms of the material, the optical properties, and the geometrical dimensions.
[0286] A substrate 20 modified in accordance with the invention here includes at least one modified region 22 which fulfills at least one of the following characteristics: [0287] Total Thickness Variation (TTV): <=1 μm or <=0.75 μm or <=0.5 μm, optionally <=0.4 μm, more optionally <=0.3 μm, or even <=0.2 μm; [0288] Local Slope: <=0.3 arcmin, <=0.16 arcmin, optionally <=0.13 arcmin, more optionally <=0.10 arcmin; [0289] Warp: <=100 μm, optionally <=70 μm, more optionally <=50 μm; [0290] Bow: −50 μm<=Bow<=50 μm; [0291] Roughness: R.sub.q<=1 μm, optionally <=100 nm, more optionally <=10 nm.
[0292] At least one of these characteristics may also be valid for the entire surface 21 or the entire substrate 20, if, for example, a surface 21 is modified in its entirety.
[0293] Where only a region of a surface 21 is modified, accordingly, the substrate 20 may possess at least one further, second region which is unmodified and which may fulfill at least one of the following characteristics: [0294] Total Thickness Variation (TTV): <=10 μm; [0295] Local Slope: <=1 arcmin; [0296] Warp: <=100 μm; [0297] Bow: −100 μm<=Bow<=100 μm; [0298] Roughness: R.sub.q<=10 μM.
[0299] The substrate 20 of the invention includes at least one modified region 22 which possesses a near-surface marginal region having a depth of up to 500 nm, optionally of at least 40 nm to 400 nm, this near-surface marginal region being free or largely free from accumulation of cerium oxide.
[0300] In one optional embodiment this near-surface marginal region having a depth of up to 500 nm, optionally of at least 40 nm to 400 nm, is also free or largely free from accumulations of potassium.
[0301] This means that for cerium oxide and/or potassium, the concentration in this near-surface marginal region corresponds to the concentration in the bulk and is not increased.
[0302] The substrate 20 of the invention may further include at least one modified region which may possess a directed arrangement of fine grooves in the nanometer or subnanometer depth range. These grooves may have a length of a few micrometers and be ascertained by way of AFM measurements. This may distinguish modified regions 22 of the substrate 20 from other surfaces of other substrates, such as, for example, unmodified surfaces or surfaces of substrates which have been polished by way of known methods of fine working. As a result of lapping methods, for instance, fine grooves of nanometer or subnanometer depth range of this kind may be formed, having an irregular arrangement, in other words being present with a random distribution over the corresponding region.
[0303] In accordance with the invention a substrate 20 may be provided, the substrate 20 including a multicomponent glass, having at least one surface 22 modified at least regionally or in portions, which has fewer than 100, optionally fewer than 50, optionally fewer than 20, optionally fewer than 10, optionally fewer than 5 and with further option fewer than 2 scratches in a region of 2 μm x 2 μm, where a scratch has: [0304] a length in the range from 100 nm to 15 000 nm, optionally from 250 nm to 10 000 nm, optionally 300 to 5000 nm, and with further option 400 to 2800 nm; [0305] a depth of 0.5 to 100 nm, optionally 1-50 nm, optionally 10-25 nm; and [0306] a width of 0.5 to 50 nm, optionally 1 to 25 nm, and with further option 2 to 10 nm.
[0307] In yet a further aspect the invention relates to the use of a substrate as described above, more particularly for applications in the field of augmented reality, examples being imaging optical systems, or as a cover for microelectronic systems, for example sensors, cameras.
[0308] The particle-beam modifying of at least one region of a surface and/or portion of a substrate in accordance with the invention may also be used for modifying or polishing high-quality wafers, carrier wafers or patterned wafers for applications including wafer level packaging (WLP), including 3D-IC (“three-dimensional integrated circuit”), RF-IC (“radiofrequency integrated circuit”) or camera imaging applications, wafer level optics, pressure sensor packaging, laser diode packaging, camera imaging packaging, wafer level optics packaging or LED packaging, fan-out wafer level packaging (FOWLP), back-grinding applications (lapping and polishing of silicon wafers) or, generally, applications involving very stringent requirements with regard to the geometric properties such as TTV, bow, warp or roughness of the wafers.
[0309] While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.