DE102007004043A1 - Process for the production of semiconductor-based optical waveguide structures with special geometrical shapes - Google Patents

Abstract

A multi-stage manufacturing process for waveguide structures is presented. The waveguide structure is subdivided into sections which are produced by means of different etching processes from a monocrystalline component layer. At least one etching process is crystallographic-anisotropic. The method makes it possible to combine the high precision of crystallographic-anisotropic etching processes with the geometric diversity that have geometry produced by other etching processes in terms of their geometry. The edges of the waveguide structure are oriented in the crystal-oriented portion such that the later sidewalls substantially coincide with stable planes of the crystal lattice. As a result, the position of the side walls is defined very precisely and it can be produced with high precision cross-sectional geometries that can not be achieved with conventional, for example, dry chemical processes. Such a method can be used in particular for structuring waveguides in the monocrystalline device layer of SOI wafers. Known crystallographic-anisotropic etching methods can be used in which the {111} planes represent stable crystal planes. As a result, it is possible to produce various cross-sectional geometries which depend both on the crystal orientation of the component layer and on whether and to what extent the etching processes preceding the crystallographic-anisotropic etching process are ...

Description

Field of the invention

The The invention relates to a production method for semiconductor-based optical waveguide structures with special geometric shapes and such an optical waveguide device, and is the field of integrated optics. In particular the invention a method that allows optical waveguide structures with special, well-defined shapes in layers of monocrystalline Structure material. This procedure can be in particular for the production of waveguides in silicon on insulator layers (SOI) use. It is of great importance to the Realization of low-loss optical and electro-optical components on a common substrate with electronic components.

Background of the invention

The Use of light to transmit information provides a number of advantages over purely electrical processes, especially when high data rates are needed and / or great distances are to be overcome. While but increasingly for the transmission of data optical methods are used, the digital processing takes place and storage of information still electronic. A play a major role in this integrated components, the on Base of semiconductors (especially silicon, eg complementary Metal Oxide Semiconductor Technology (CMOS)). There is therefore a great deal of interest, the semiconductor-based electronic information processing and storage and the to combine optical information transmission also technologically and the corresponding components on a common substrate integrate. For this, structuring methods are needed which are capable of compact optical waveguide structures with very accurate defined geometries in semiconductor materials inexpensively to create.

The light guidance in these structures takes place either in regions of high refractive index which are surrounded by materials of lower refractive index (index guide), or else multiple reflections at the dielectric interfaces between regularly arranged media are used, which are used to form a photonic band gap bandgap, PBG) (cf. Joannopoulos, Photonic Crystals: Molding the Flow of Light, Princeton University Press, ISBN: 0-691-03744-2, Jul. 1995) , Often, a combination of both guiding mechanisms is used, for example, by patterning a high refractive index layer so as to have a photonic bandgap in the horizontal direction while having indexing in a vertical direction. For the realization of PBG structures, for example, methods of interest, which can be produced in shape and position very well-defined cavities.

In general, the optical properties of an optical waveguide are determined not only by its core material, but also by the low-refractive cladding or surrounding material surrounding the core. This fact can be used to provide certain sections of a waveguide with desired optical properties by applying suitable cladding materials, regardless of the core material. For index-guided waveguides, the interaction of the guided light with the cladding material can be increased by a special design of the core cross-section, for example by deliberately exploiting the discontinuous exaggeration of the normal component of the electric field at the core-cladding interface (cf. Almeida et al., Guiding and confining light in void nanostructure, Opt. Lett. 29 (11), p. 1211ff, 2004 ). This in turn requires structuring methods that allow specific, well-defined profiles such. B. trench structures or in the propagation direction to produce open cavities. This principle is also interesting for PBG structures in which, for example, open cavities in a high refractive index material are filled with suitable low-index interaction materials.

For the production of optical waveguides in semiconductor materials Wafers that contain at least one single crystal can be used Have layer. Polycrystalline or even amorphous semiconductor materials generally have large absorption losses and / or an insufficient surface quality on. From the monocrystalline layer of the waveguide core or shaped the PBG structure.

Currently are used to pattern optical waveguides in semiconductor materials almost exclusively anisotropic dry chemical etching used. Here are usually reactive ion etching (Reactive Ion Etching, RIE) for use, for special Applications will also use ion beam etching (Ion Beam Etching, IBE) or chemically assisted ion beam etching (Chemically Assisted Ion Beam Etching, CAIBE, or Reactive Ion-Beam Etching, RIBE). These methods allow for appropriate optimization the process parameter involves the production of semiconductor structures vertical or almost vertical side walls.

However, these dry chemical anisotropic etching processes have several disadvantages in structuring optical waveguides the obtained cross-sectional geometries are sensitive to the process parameters which have to be optimally optimized. Slight variations of these parameters directly translate into altered geometry or surface roughness degradation. In addition, it is not or at least insufficiently possible to achieve waveguides or cavities whose side walls differ significantly from the vertical. Although a certain undercut or overcut, and thus for index-guided waveguide, for example, a slightly trapezoidal cross-section can be achieved, but this depends again sensitive to the Ätzparametern. From a trapezoidal shape significantly different, high-precision cross-sectional geometries are virtually impossible to achieve. Furthermore, inaccuracies of the etching mask, in particular rough edges, are transferred directly to the sidewall of the waveguide or the cavity. In addition, when structuring narrow, deep trench structures or open cavities, there is often the problem that the etching rate at the bottom of these trenches or in the interior of the cavities is lower than for areas exposed over a large area. This can lead to the trenches or cavities being etched only incompletely, deviating from the desired profile and / or having roughnesses in the lower areas, which in turn lead to scattering losses. Roughnesses at the bottom of the trench or in the cavity are particularly problematic when used there for the use of Almeida et al. described principle high field strengths prevail in order to exploit the interaction with a deposited there, low refractive index material. Damage to the crystal lattice may also be disadvantageous for some applications, as are caused, for example, by ion bombardment during such a dry chemical etching process.

The achievable surface roughnesses could be drastically reduced for freestanding waveguides by optimizing the etching processes in recent years, but still have a noticeable influence on the waveguide losses and possibly require suitable aftertreatment processes. Such aftertreatment methods for reducing roughnesses in silicon-based waveguides are described, for example, in Lee et al., Fabrication of ultralow loss Si / SiO ₂ waveguides by roughness reduction, Opt. Lett. 26 (23), p. 1888ff, 2001; in US 2002/0031321 A1 and in US 2005/0013575 A1 described. The pre-structured waveguide core is hereby subjected to one or more chemical reaction steps, which lead to a reduction of the scattering losses. These steps may include isotropic or anisotropic etch processes that flatten the surface of the waveguide, or they may be reactions that chemically alter (eg, oxidize) the rough surface and thereby reduce scattering losses. The two methods can also be combined by abrading a previously chemically altered rough surface through a material-selective etching process and leaving behind a smoothed surface.

apart from these aftertreatment methods for reducing roughness freestanding waveguide ribs are wet-chemical etching processes in the manufacture of complex optical waveguides in semiconductor materials only extremely rarely used. For isotropic wet-chemical etching processes, that is, those in which the etching rate is not of the crystal direction depends on the difficult control of the cross-sectional geometry lie: the mask is constantly undercut from the sides, so that the etching rate and etching time are controlled very accurately Need to become.

In the case of anisotropic wet-chemical etching processes, by contrast, the etching rate depends very strongly on the crystal direction. For example, in certain etching liquids in silicon, the etching in the <111> direction takes place much more slowly than in all other directions (cf. Seidel et al., Anisotropic Etching of Crystalline Silicon in Alkaline Solutions, J. Electrochem. Soc. 137 (11), p. 3612ff, 1990 , such as Tabata et al., Anisotropic etching of silicon in TMAH solutions, Sensors and Actuators A34, p. 51ff, 1992 ). These anisotropic wet-chemical etch processes have been used mainly for the production of micromechanical components (MEMS) in silicon. However, in the manufacture of integrated optical waveguides, they have only been used as described in the Lee et al. as in US 2002/0031321 A1 and US 2005/0013575 A1 described - used to reduce the surface roughness of freestanding waveguide ribs. However, these documents only concern the smoothing of pre-structured waveguide cores. In particular, they do not include any methods which make it possible to achieve special cross-sectional geometries or open cavities with high aspect ratios that can not be achieved using conventional methods. In US 2005/0013575 A1 For example, waveguide structures produced by anisotropic wet-chemical etching processes, which have cross-sectional profiles that depend strongly on the direction of the waveguide, are even considered problematic.

Anisotropic wet-chemical etching processes have hitherto at best been used to improve the surface quality of simply cylindrical waveguide structures. In this context, waveguide structures whose direction and their cross-sectional profile do not change along the propagation direction of the light, ie which have the shape of a cylinder in the general sense, are referred to as simply cylindrical. However, the known anisotropic wet-chemical etching methods can not be used for waveguide structures. which do not have a simple-cylindrical shape, so z. For example, those containing curves or tapered sections. This substantial limitation on achievable geometries has heretofore made the use of wet-chemical anisotropic etching processes, despite their numerous advantages, unsuitable for producing complex waveguide structures.

General description of the invention

It is therefore an object of the present invention, a versatile Process to provide, which for the production of a variety of different, even very complex waveguide structures is suitable with differently structured sections and at the same time delivering high-precision results, among others to achieve a higher integration density. Another The object of the invention is the object of the invention is such Manufacturing process for complex waveguide structures to provide the benefits of wet-chemical anisotropic etching Known advantages associated with diversity by other etching techniques manufactured structures in terms of their manufacturable geometry Have structures.

The Process is intended in particular for the production of not simply cylindrical Waveguide structures suitable.

These Structures can be waveguide cores and cavities with exactly defined geometries and high aspect ratios included, and the profiles obtained should be robust slight fluctuations in the process parameters. Furthermore, in certain areas of the structure damages the crystal lattice be reduced to a minimum. The method is also intended in the Be able to prevent inaccuracies of the etching mask, in particular rough side edges, compensate. This is especially for very small optical Structures important, since the lithography process with decreasing Structure size to become more sophisticated and the relative inaccuracies increase. On the other side it should enable complex structures.

The The object of the invention is achieved by the subject matter of the independent Claims solved. Trainings are in defined in the subclaims.

To is a multi-step process according to the invention used in which a waveguide structure in at least two sections is divided, with different etching methods be structured from a single-crystalline device layer, wherein at least an etching process is crystallographic-anisotropic. Under a crystallographic-anisotropic etching process in the following a wet or dry chemical etching process understood, in which the etching rate to a great extent depends on the crystal direction. As a minimum requirement for a crystallographic-anisotropic etching process It should be understood that the etch rates for the different crystal directions in at least two groups having each of the etch rates of the first group is at least a factor of 2 greater than any etch rate the second group. The second group, ie the one with the smaller etching rates, belonging crystal directions are hereinafter referred to as "stable Directions ", which are perpendicular to these directions crystallographic Layers referred to as "stable levels". The stable levels form the sidewalls of the waveguide to be structured and have one through the crystal lattice of the single-crystalline device layer very precise orientation. Ie. the anisotropy of the crystallographic-anisotropic etching process is determined by the crystal lattice of the monocrystalline material.

starting point for structuring according to the invention of optical waveguides is therefore a material system that is made consists of several layers. Of these, at least one layer is monocrystalline and has at least one crystallographic-anisotropic etching process at least one stable level. In the areas of the component layer, the structured by crystallographic-anisotropic etching be, the edges of the waveguide structure parallel to Line of intersection of the stable crystal planes with the plane of the wafer. These sections of the waveguide structure will therefore be described below referred to as "crystal-oriented sections". In all others Areas of the component layer must have the structural edges not necessarily aligned with the direction of the crystal lattice be; these sections of the waveguide structure can, But they do not necessarily have to be crystal-oriented and are therefore hereinafter referred to as "arbitrarily oriented sections" designated.

The Crystal orientation is below using Miller's indices described. Thereby direction vectors become whole by triple Figures given the components of the vector in multiples describe the respective edge length of the unit cell. [ijk] represents a crystal direction and denotes <ijk> the totality of crystal directions, characterized by axis permutations and inversion from [ijk]. Analog (ijk) refers to the [ijk] vertical crystallographic plane, while {ijk} includes the totality of levels, characterized by axis permutations from (ijk).

In an exemplary crystallographic-anisotropic etching process, potassium hydroxide (KOH), ethylenediamine pyrocatechol (EDP) or tetramethylammonium hydroxide (TMAH) is used to etch a single-crystal silicon device layer used. The exact etching rates depend on many parameters - the concentration, the temperature and the degree of freshness of the etching solution, the total area to be etched, etc. Therefore, all etch rates mentioned below are to be understood as rough indications. In particular, at the bottom of cavities or trenches with a high aspect ratio, a reduction in the etching speed may occur, so that a certain overetching must be provided for such structures. Since in the inventive production of optical waveguide structures from the said material systems usually relatively little material must be removed (preferably less than 10 microns, more preferably less than 1 micron), in the present example, the etching rates in the <100> - and <110> Directions preferably less than 2000 nm / min, more preferably less than 100 nm / min. The etch rates for in the <100> and <110> directions are also preferably more than a factor of 5 greater than the etching rate in the <111> direction, more preferably more than a factor of 20. In support of the etch process and To prevent gas bubbles from forming on the surface of the etched material, the etching solution may be agitated or ultrasonicated during the etching process. As etch masks, thin layers of silicon dioxide or silicon nitride can be used. In order to ensure an optimal attack of the etching liquid on the silicon surfaces to be etched, the natural oxide layer is removed - for example by briefly immersing the sample in dilute hydrofluoric acid.

For Potassium hydroxide are preferred concentrations of the KOH solution between 10% and 60% (each weight percent of KOH in solution), and the temperature of the etching solution is preferable between 10 ° C and 80 ° C, more preferably between 20 ° C and 60 ° C. This allows etch rates between 5 nm / min and 1200 nm / min for the <110> directions or between 4 nm / min and 800 nm / min for the <100> directions. The etch rates for the <111> directions are typically smaller by more than a factor of 30 respective etch rate for the <100> directions. In an exemplary experiment, a 340 nm thick <100> oriented device layer was used with a solution with 45% KOH content at 25 ° C in etched through for about 17 minutes, giving an etch rate of about 20 nm / min corresponds. An etching in the <111> direction was in this Experiment not measurable.

Also for ethylenediamine pyrocatechol, the etch rates vary for single crystal silicon strong with the composition. For an exemplary mixture of 133 ml deionized water, 1000 ml of ethylenediamine, 160 g of 1,2-dihydroxybenzene (pyrocatechol) and 6 g Pyrazine are preferred temperatures in the range between 10 ° C. and 80 ° C, and there are etch rates between 26 nm / min and 380 nm / min for the <110> directions or between 11 nm / min and 300 nm / min for <100> directions. The etching rates for the <111> directions are typical more than a factor of 30 smaller than the respective etching rates for the <100> directions.

For aqueous tetramethylammonium hydroxide solutions preferred TMAH concentrations are greater than 5 wt .-%, and preferred temperatures are between 10 ° C. and 80 ° C. This allows etching rates up to 1900 nm / min for the <110> directions or until 1400 nm / min for the <100> directions. Depending on the concentration and the temperature are the etch rates for the <111> directions a factor 20 to 50 smaller than the respective atzrate for the <100> directions. By Extrapolation of the above-mentioned article by Tabata et al. published data can also be seen that the at rates for the <100> directions and the <110> directions are partial differ by more than a factor of 10. For a concentration of TMAH of 40% by weight and a temperature of 30 ° C For example, etch rates of 3-5 nm / min for estimate the <100> directions, whereas the etching in the <110> direction is about 90 nm / min he follows. In this case, the {100} levels can also be used considered as stable levels over the {110} planes become.

at III-V and II-VI compound semiconductors should be noted that different Crystal planes of the same index group extremely different etch rates can have.

For For example, III-V semiconductor depends on the etching rate in the <111> directions strongly depending on whether the respective surface atoms are around Elements of the third or fifth main group. In the former case, the surfaces are commonly referred to as (1 1 1), sometimes also denoted by A {111}, in the latter case with (-1 -1 -1) or sometimes with B {111}. The (1 1 1) surfaces generally have much lower etch rates on as the corresponding (-1 -1 -1) levels.

For III-V semiconductors, a large number of etching liquids are known in the literature, which - depending on the composition - may have a crystallographic anisotropic behavior which, although weaker than that of silicon, is nevertheless sufficient for the inventive production of optical waveguide structures can. For InP, for example, aqueous solutions of hydrochloric acid and nitric acid can be used. Low concentration (<1% by volume) solutions of bromine in methanol can be used for both InP and GaAs. Stable levels are each the (1 1 1) levels, whereas the (-1 -1 -1) levels sometimes have considerably higher etching rates.

For For example, the II-VI semiconductor InSb can be solutions made of nitric acid and hydrogen peroxide.

Further Details on crystallographic-anisotropic etching for silicon, the skilled person will find in the above Articles by Seidel et al. and Tabata et al., which are hereby incorporated by reference Reference be incorporated.

The Structuring of the arbitrarily oriented sections is preferably carried out by etching processes, which is a strongly anisotropic physical Have component, ie z. B. reactive ion etching (Reactive Ion Etching, RIE, or Inductively Coupled Plasma Etching ICP), ion beam etching (IBE) or chemically assisted ion beam etching (Chemically Assisted Ion Beam Etching, CAIBE, or Reactive Ion Beam Etching, RIBE). This typically results in sidewalls, which have a slight inclination inwards or outwards. Arbitrarily oriented portions of the waveguide structure included preferably functional elements whose geometry is not exclusive with the available stable crystal planes can define. These include, for example, waveguides, who change their direction continuously or abruptly, themselves tapering or widening waveguides (so-called taper), Branches, couplers (for example directional couplers, or else multimode interference couplers, MMI), ring resonators, waveguides of varying width and / or height (Waveguide Bragg gratings), waveguides with special structured Surfaces for coupling and coupling in light (lattice coupling) etc.

The In contrast, crystal-oriented sections are preferred for Functional elements used, whose geometry with the stable crystal planes is compatible, and where it is very strong on a high geometric Precision arrives or where special structural geometries should not be achieved by other etching methods are reachable. These include, for example, waveguides with in the direction of propagation strictly homogeneous, polygonal Cross-sectional profiles and / or high aspect ratios. With the method according to the invention can Waveguide structures are created with ribs and trenches, the aspect ratios (ratio of width to height or depth) of significantly more than 5. In addition, structures can be made that have a through the crystal lattice determined in the longitudinal direction very homogeneous Own geometry, even if the etching masks inaccuracies have (for example, rough or irregular side edges).

These In particular, crystal-oriented cross-sectional profiles can also in the direction of propagation extensive trenches or open Have cavities with a high aspect ratio, whose sidewalls represent stable levels and therefore are defined very precisely in their position. Furthermore, can by applying crystallographic-anisotropic etching processes from each other isolated, polyhedral open cavities produced whose sidewalls again represent stable levels and therefore are very well defined in their location. By a suitable arrangement of such cavities can be waveguide structures produce, which have a photonic band gap, and which can therefore be used to guide light.

• (a) Bereitstellen eines mehrschichtigen Substrats mit einer mechanisch stabilen Trägerschicht und zumindest einer einkristallinen Schicht aus einem hochbrechenden Material, die als Bauteilschicht für die nachfolgende Strukturierung der Wellenleiterstruktur dient,
• (b) Unterteilen der einkristallinen Bauteilschicht in zumindest einen ersten Bereich für zumindest einen kristallorientierten oder nicht-kristallorientierten, also beliebig orientierten, ersten Abschnitt der Wellenleiterstruktur und zumindest einen zweiten Bereich für zumindest einen kristallorientierten zweiten Abschnitt der Wellenleiterstruktur,
• (c) Strukturieren der einkristallinen Bauteilschicht in einem ersten Ätzschritt mittels einer zumindest auf dem ersten Bereich der einkristallinen Bauteilschicht aufgebrachten strukturierten Ätzmaske, wobei in dem ersten Ätzschritt zumindest der erste Abschnitt der Wellenleiterstruktur in dem ersten Bereich aus der einkristallinen Bauteilschicht erzeugt wird,
• (d) Strukturieren der einkristallinen Bauteilschicht in einem zweiten Ätzschritt mittels einer zumindest auf dem zweiten Bereich der einkristallinen Bauteilschicht aufgebrachten strukturierten Ätzmaske, wobei in dem zweiten Ätzschritt der zweite Abschnitt der Wellenleiterstruktur in dem zweiten Bereich aus der einkristallinen Bauteilschicht erzeugt wird.

The multi-stage production process can be divided into the following main steps:

• (a) providing a multilayer substrate having a mechanically stable carrier layer and at least one monocrystalline layer of a high refractive index material, which serves as a device layer for the subsequent structuring of the waveguide structure,
• (b) subdividing the monocrystalline device layer into at least one first region for at least one crystal-oriented or non-crystal-oriented, ie arbitrarily oriented, first section of the waveguide structure and at least one second region for at least one crystal-oriented second section of the waveguide structure,
• (c) structuring the monocrystalline device layer in a first etching step by means of a structured etching mask applied to at least the first region of the monocrystalline device layer, wherein in the first etching step at least the first section of the waveguide structure is generated in the first region from the monocrystalline device layer,
• (d) structuring the monocrystalline device layer in a second etching step by means of a structured etching mask applied to at least the second region of the monocrystalline device layer, wherein in the second etching step the second section of the waveguide structure is generated in the second region from the monocrystalline device layer.

In this case, in the second etching step, a crystallographic-anisotropic etching method is used, by means of which second faces of the second section of the waveguide structure are formed in the second region, which are parallel to stable planes of the crystal, ie are crystal-oriented, the edges of the etching mask in the second section are aligned substantially in a predetermined orientation to the crystal lattice. In the case of sufficiently short edge sections, no special consideration must be given to the crystal orientation, since in the case of crystallographic-anisotropic et An undercut of the mask is made to the first fully protected stable crystal plane, and local misalignment of the mask edge is automatically corrected.

in the the first etching step becomes at least one side surface of the first waveguide section is generated so as not to be the crystal-oriented side surfaces of the second section the waveguide structure is parallel.

ever according to structure further embodiments of the method are possible for example, more crystal-oriented or non-crystal oriented sections as well as further etching steps be provided. In particular, the order of the masking and etching steps (c) and (d) not by the enumeration order be limited. For a preferred embodiment can be, for example, the structuring of the crystal-oriented Section (main step (d)) in the following closer Divide the steps you have taken. Depending on the desired structure Steps 2 and 4 are optional.

step 1: In a first step, one or more etch masks generates at least the crystal-oriented portions of the waveguide structure define. The edges of these etching masks run in the crystal-oriented Area substantially parallel to the cutting line of the stable Crystal planes with the plane of the wafer. The etching masks consist of a material that the subsequent treatment steps sufficiently withstood. In a simple In the case, the mask structures can be directly through a lithographic Method (eg photolithography, electron beam lithography, X-ray lithography, etc.) are generated. Possibly. can for the preparation of the etching mask a multi-step process be necessary. Such a method includes, for example the large-area deposition of a suitable mask material, followed by lithographic steps to define structures on the mask material and etching processes for transfer of these structures in the mask material. Other methods of manufacture The mask is based, for example, on lift-off techniques in which Initially, structures are created by lithography. The mask material (eg a metal) then becomes these structures usually deposited under high vacuum. Then be the lithographically generated structures by a suitable solvent removed along with the mask material deposited thereon while the remaining areas are covered by the mask material. Such lithography methods are the expert in principle known.

step 2: In an optional second step, in the not of the mask material covered areas one or more layers of the material system completely or partially removed. This can be done in one or more times done several stages. It can either layers are removed above the monocrystalline layer (s) lie, or the monocrystalline layer / s themselves can be structured in such a way that stable levels are broken, where the crystallographic-anisotropic etching process otherwise heavily delayed or even stopped in step 4 would. This process can be of great importance be for the ultimately achieved form. More details are explained below in connection with the embodiments.

step 3: In a third step, the exposed areas of the single crystal layer (s) of one or more crystallographic anisotropic etch processes exposed, between which possibly covered areas with a mask, Masks away from certain areas or further, possibly not crystallographic-anisotropic etching processes be performed. This preserves the waveguides or the cavities in the region of the monocrystalline layer (s) at least one sidewall, which is a stable plane of the crystal is. The thus generated crystal-oriented parallel to stable planes aligned side walls have a through the crystal lattice exactly given position and possibly inclination, so can an oblique Include angles with the substrate surface, and have an approximately atomically smooth surface. In particular, the edge follows the waveguides or the cavities very precisely the line of intersection of the stable plane with the surface. Inaccuracies in lithography, especially locally misaligned or rough edges of the etching masks, are characterized by the Crystallographic-anisotropic etching automatically compensated. Furthermore, waveguides or cavities can be produced, whose sidewalls have slopes that are dry chemical anisotropic etching alone or not at least would be feasible with much lower precision. In particular, these side walls may consist of several, one be composed of cutting stable levels. more details are below in connection with the embodiments explained.

• i) Strukturierung einer Maske zum Abdecken bestimmter Bereiche.
• ii) Eine von der Oberfläche her erfolgende und mit zunehmender Zeitdauer in die Tiefe vordringende chemische Reaktion.
• iii) Ein materialselektiver Ätzprozess, der beispielsweise Ätzmasken oder bestimmte Schichten entfernt oder dazu dienen kann, die durch ii) erzeugten Reaktionsprodukte zu entfernen.

Step 4: In an optional fourth step, the structures thus obtained are exposed one or more times to one or more of the following processes:

• i) structuring a mask to cover certain areas.
• ii) A chemical reaction taking place from the surface and penetrating with increasing duration.
• iii) A material-selective etching process, which can remove or serve, for example, etching masks or certain layers, which are characterized by ii) to remove generated reaction products.

In order to The geometry of the structure can be decisive Change way, for example, the light-guiding Layer of adjacent layers freed, in sections disassembled and / or certain parts of it are separated. Further Details are below in connection with the embodiments explained. The achievable changes in this step The structural geometry goes well beyond the mere Smooth out a surface.

The Steps 1-4 can be repeated or in another Sequence can be executed as described. For example can be achieved by using Focused Ion Beam (FIB) techniques a single operation, a mask layer and parts of the underlying Structure (component) layers (step 1 and 2) after the Mask layer was applied (step 3).

The Steps 1-4 relate to the preparation of the crystal-oriented ones Sections of the waveguide structure. The structuring of or the arbitrarily oriented sections may be, for example, before step 1 done with a separate etching mask. In this case will be the arbitrarily oriented sections through a protective mask the crystallographic-anisotropic etch in step 3 protected. Alternatively, the etch mask generated in step 1 For example, both the crystal-oriented and the arbitrarily oriented Include sections, and structuring of any oriented Sections are done in step 2 along with pre-structuring the crystal-oriented sections. Also in this case will be the arbitrarily oriented sections through a protective mask the crystallographic-anisotropic etch in step 3 protected. Furthermore, the arbitrarily oriented For example, sections may also be generated after step 4 - in In this case, the crystal-oriented sections with before a protective mask provided.

The structured waveguides or open cavities can then be surrounded or filled with materials which have a smaller refractive index than the material of the component layer and provide desired optical or electro-optical functionalities. Due to the high precision with which the cross-sectional geometry of the waveguides is defined by the crystal lattice, the crystal-oriented sections of the waveguide structure are particularly well suited for this purpose. This is in 1 schematically illustrated. The light-guiding area or waveguide core 2 has at least one sidewall parallel to a stable plane. After structuring, it becomes so through various low-index environmental materials 6 . 7 . 8th . 9 and 10 surrounded, that in the waveguide guided light interacts with these materials. As a result, special optical or electro-optical properties are exploited in at least one of these materials. The drawn shape of the sphere 2 is to be regarded as exemplary, - possible implementation forms are given below as exemplary embodiments. To achieve a strong interaction of the guided light with the surrounding materials, at least one component of the light-guiding region should be 2 have a width which is of the order of the wavelength of the light in the core material 2 or below.

Examples of such filling or surrounding materials 6 - 10 are hydrocarbon compounds (in particular conjugated polymers in crystalline, partially crystalline or amorphous form, polymers with special functional groups (chromophores), liquid crystals), special glasses (especially lead glasses, halide or chalcogenide glasses, tellurium oxide-containing glasses, bismuth oxide-containing glasses) or doped or undoped semiconductor compounds. In addition, these materials may be provided with artificial structures on a size scale below the wavelength of light in that material (eg, nanocrystals, quantum dots, or quantum wires).

The interaction of the guided light with one or more of the fill or surrounding materials 6 - 10 For example, it can be used to absorb, detect, generate or amplify light. It is also possible to use nonlinear optical effects, in particular self-phase modulation (SPM), cross-phase modulation (XPM), the generation of higher harmonics (second / third harmonic generation, SHG / THG). ), Four-wave mixing (FWM) or nonlinear optical absorption such as two-photon absorption (TPA). Furthermore, electro-optical interactions can be exploited. These include in particular the linear electro-optical effect for the construction of modulators, or the utilization of second-order non-linearities for the detection of light (optical rectification). The interactions mentioned can also be used to construct compact optical sensors in which, based on the linear or nonlinear transmission or reflection behavior of a waveguide structure, information about the physical or chemical properties or environmental conditions of all or part of the low refractive filling or surrounding materials is obtained.

The inventive method also makes it possible to produce in the crystal-oriented sections optical waveguide structures whose Oberflä have certain defined by the particular crystallographic level chemical properties. By suitable preparation of these surfaces, for example by the application of receptor molecules, the preferred attachment of certain substances can be achieved and detected on the basis of the transmission behavior of the waveguide. This allows the construction of compact optical sensors.

in the The invention will be described below with reference to exemplary embodiments and explained in more detail with reference to the figures, where the same and similar elements are partly the same Reference numerals are provided and the features of the various embodiments can be combined with each other.

Brief description of the figures

It demonstrate:

1 a schematic representation of a surrounded with interaction materials waveguide core,

2 a plan view of an embodiment of the waveguide structure according to the invention, the three crystal-oriented sections 11a . 11b . 11c and two arbitrarily oriented sections 10a . 10b includes,

3 Cross-sectional views along in 2 illustrated lines P ₁ -P ₂ and P ₃ -P ₄ during the manufacturing process,

4 a plan view of an embodiment of the waveguide structure according to the invention, the two crystal-oriented sections 11a . 11b and two arbitrarily oriented sections 10a . 10b includes,

5 Cross-sectional views along in 4 illustrated lines P ₅ -P ₆ and P ₇ -P ₈ and P ₉ -P ₁₀ during the manufacturing process,

6 Examples according to the invention in the crystal-oriented region of producible cross-sectional geometries in a <100> -oriented component layer with stable {111} planes,

7 Examples of a Cavity Produceable According to the Invention in the Crystal-Orientated Region, in a <100> Oriented Component Layer with Stable {111} Layers ((a) Outline, (b) Side Crack, (c) Floor Plan, (d) Projection),

8th Examples of a Cavity Produceable According to the Invention in the Crystal-Orientated Area in a <100> Oriented Component Layer with Stable {111} Layers ((a) Outline, (b) Side Crack, (c) Floor Plan, (d) Projection),

9 Examples according to the invention in the crystal-oriented region of producible cross-sectional geometries in a <110> -oriented component layer with stable {111} planes,

10 Examples of a Cavity Produceable According to the Invention in a Crystal-Orientated Region in a <110> -oriented Component Layer with Stable {111} -planes ((a) elevation, (b) side elevation, (c) floor plan, (d) projection),

11 Examples according to the invention in the crystal-oriented region of producible cross-sectional geometries in a <111> -oriented component layer with stable {111} planes,

12 Examples of a cavity which can be produced according to the invention in the crystal-oriented region in a <111> -oriented component layer with stable {111} planes ((a) elevation, (b) side elevation, (c) ground plan, (d) projection).

Detailed description the embodiments

The The following exemplary embodiments relate to structural geometries, which can be generated in the crystal-oriented sections. In this case, a component layer of a monocrystalline material based on a diamond or zinc blende structure. This layer is in the crystal-oriented areas with crystallographic-anisotropic etching structured, where the stable lattice planes are {111} planes. The underlying layer and the etching mask is sufficient resistant to the crystallographic-anisotropic etching process.

A prominent example of such a material system is Silicon-on-Insulator (SOI). In a simple case, the layer sequence consists of a silicon substrate 1 as a mechanical support material, a sufficiently thick layer of SiO ₂ (oxide layer or buried oxide, English Buried Oxide, BOX) and an overlying layer 2 made of single-crystal silicon (device layer, DEV). In the figures, the BOX layer is not shown for the sake of simplicity.

If the component layer is then etched with potassium hydroxide solution (KOH), ethylenediamine pyrocatechol (EDP) or tetramethylammonium hydroxide (TMAH), the etching rates with which the crystal is removed in the <111> direction are considerably smaller than the rates at which the removal in <100> or <110> direction takes place. The {111} levels are the stable levels in these methods. As a sufficiently etch-resistant mask material, for example, come Sili ziumverbindungen (SiO _x , SiN _x ) in question. The monocrystalline device layer can be inexpensively formed with various crystal orientations, for example, by a method used by SOITEC under the proprietary name "Smart Cut".

When Crystal orientation of the device layer is hereafter the entirety crystallographic direction <ijk>, which is from the vector perpendicular to the surface of the layer results; the surface itself is then an {ijk} plane. Depending on the crystal orientation and dependent of whether and how structuring is done in step 2 waveguides or PBG structural elements with different geometric shapes can be used produce.

1. combination of functional elements in the crystal-oriented and arbitrarily oriented areas

An important aspect of the present invention relates to the combination of different functional elements in the crystal-oriented and randomly oriented sections of the waveguide structure to be produced. The functional elements of the arbitrarily oriented sections can serve, for example, as supply lines or connections of the functional elements of the crystal-oriented sections. This is in 2 and 4 outlined as an example.

2 shows an example of a waveguide device according to the invention in the form of a Mach-Zehnder interferometer. In the crystal-oriented sections 11a . 11b and 11c has the generally with 30 designated waveguide structure on a single-cylindrical shape. This includes two waveguides 40 . 50 consisting of two optically isolated from each other individual ribs 42 . 44 . 52 . 54 (Section 11a ; respectively. 11c ). Furthermore, the component comprises two mutually spaced double rib waveguides 60 . 70 (Section 11b ), in which the electromagnetic field of the guided light in each case over both ribs 62 . 64 . 72 . 74 and the gap or ditch in between 66 . 76 extends. The double rib waveguide 60 . 70 allow a strong interaction of the guided light with the material in the gap 66 . 76 However, at the same time, they also require a high level of manufacturing precision. This is achieved with the invention. The arbitrarily oriented sections 10a and 10b each contain an MMI coupler in this example 82 . 92 and two waveguide curves each 84 . 86 . 94 . 96 with curved side walls 86a . 86b . 94a . 94b , Thus, the light passes through the elongated and serial waveguide sections 42 . 84 . 60 . 94 . 52 on the one hand and 44 . 86 . 70 . 96 . 54 on the other hand.

The manufacturing process for the in 2 structure shown is in 3 outlined as an example. The left column shows examples of cross sections from the arbitrarily oriented section 10a along the section line P ₁ -P ₂ , the right column the corresponding cross sections of the crystal-oriented section 11b along the section line P ₃ -P ₄ . The component layer 2 is a <110> -oriented device layer, with the longitudinal edges of the waveguides in the sections 11a . 11b and 11c parallel to those in the wafer plane (in 2 parallel to the paper plane and in 3 horizontally and perpendicular to the plane of the paper) lying <112> directions of the crystal lattice. The preparation is carried out according to the above-described steps 1-4, wherein initially on the component layer 2 a structured etching mask 3 which generates the waveguide structure in both the crystal-oriented sections 11a . 11b and 11c as well as in the arbitrarily oriented sections 10a . 10b Are defined. In step 2, only the arbitrarily oriented sections are then patterned, while the crystal-oriented sections still have a protective mask 7 are covered. This is subsequently removed, and on the arbitrarily oriented sections becomes a protective mask 8th applied before in step 3, the structuring of the crystal-oriented portion by means of the crystallographic anisotropic etching process takes place. In the crystal-oriented sections, for example, this results in almost perfectly vertical side walls 72a . 72b . 74a . 74b and precisely defined trenches 76 with a high aspect ratio. If necessary, the aspect ratio, ie the ratio of trench depth to width, can be significantly greater than 5; in the case of some crystallographic anisotropic processes, it can even be significantly greater than 20.

In step 4, the protective mask 8th removed on the arbitrarily oriented sections. In this example, the etch mask remains 3 on the device.

4 shows a further example of the waveguide device according to the invention with a generally with 130 designated waveguide structure with a photonic crystal 132 in the crystal-oriented section 11b , The photonic crystal 132 consists of a plurality of periodically arranged upwardly open cavities 160 which are arranged to form a photonic bandgap in the substrate plane. Such structures can be made according to the invention with very high precision. The arbitrarily oriented sections 10a and 10b contain in this example leads in the form of a taper, called taper 182 with non-crystal-oriented sidewalls 182a . 182b and waveguide curves 194 with side walls 194a . 194b , In the crystal-oriented section 11a The device includes a wide waveguide core 140 its width by means of the tapers 182 to the smaller width of the waveguide core 161 adapted becomes. Within the photonic crystal 132 extends an elongated ditch 76 , So the light gets through the serial waveguide sections 140 . 182 . 161 . 132 . 163 . 194 guided.

The manufacturing process for the in 4 structure shown is in 5 outlined. The left column shows exemplary cross sections from the arbitrarily oriented section 10b along the section line P ₅ -P ₆ , the right column the corresponding cross sections of the crystal-oriented section 11b along the cutting lines P ₇ -P ₈ and P ₉ -P ₁₀ . The component layer 2 is a <100> -oriented device layer, with the edges of the waveguide structure in the sections 11a and 11b are oriented parallel to lying in the wafer plane <110> directions of the crystal lattice. The preparation is carried out according to the steps described above, wherein first an etching mask 3 which defines the waveguide structure in both the crystal-oriented sections and in the arbitrarily-oriented sections. In step 2, the arbitrarily oriented sections are then patterned simultaneously with a pre-structuring of the crystal-oriented sections. Subsequently, on the arbitrarily oriented sections a protective mask 7 applied before in step 3, the further crystallographic anisotropic structuring of the crystal-oriented portion takes place. This is the variety of polyhedron-shaped upwardly open cavities 160 or trenches 76 produced, which have a characteristic, precisely predetermined by the crystal lattice shape. Further details on the form are explained in the following sections. After the crystallographic-anisotropic etching, in the present example the protective and etching masks are removed by a material-selective etching process in step 4.

Further Examples of forms of crystal-oriented structures are given in the next sections for different crystal orientations of the Component layer described.

2. Crystal-oriented structures in <100> -oriented component layers

• a) Wellenleiterabschnitte mit dem in 6a) beispielhaft gezeigten Kernquerschnitt verlaufen parallel zu in der Waferebene liegenden <110>-Richtungen des Kristallgitters. Ihre Querschnittsgeometrie wird durch ein gleichschenkliges Trapez ABCD beschrieben. Die Strecken BC und AD (Seitenwände) liegen in stabilen {111}-Ebenen des Kristallgitters, die Strecken AB bzw. CD (Basis- und Deckfläche) in {100}-Ebenen, die durch die unterliegende Schicht 1 bzw. die Maske 3 vor dem Angriff der Ätzlösung geschützt werden. Für die Trapezwinkel gilt ∠CBA = ∠BAD ≈ 54.74° und ∠ADC = ∠DCB ≈ 125.26°.

6a) to f) show examples of different core cross-sections of index-guided waveguides used in a <100> -oriented device layer for the crystal-oriented waveguide sections 40 . 50 . 60 . 70 can be used.

• a) waveguide sections with the in 6a) The core cross-section shown as an example run parallel to <110> directions of the crystal lattice lying in the wafer plane. Their cross-sectional geometry is described by an isosceles trapezoid ABCD. The distances BC and AD (sidewalls) lie in stable {111} planes of the crystal lattice, the distances AB and CD (base and top surface) in {100} planes, respectively, through the underlying layer 1 and the mask 3 be protected from the attack of the etching solution. For the trapeze angle applies ∠CBA = ∠BAD ≈ 54.74 ° and ∠ADC = ∠DCB ≈ 125.26 °.

The Production of the Crystal-Oriented Section of the Waveguide Structure will be described below with reference to the above-defined steps 1-4 explained:

Step 1: The edges of the etching masks 3 are oriented in the crystal-oriented section substantially parallel to <110> directions of the crystal lattice (perpendicular to the plane of the paper) lying in the wafer plane. In the unmasked areas of the crystal-oriented section lies the monocrystalline component layer 2 free.

Step 2: The following structuring in step 2 at most concerns the arbitrarily oriented sections of the waveguide structure, z. B. 82 . 84 . 86 . 92 . 94 . 96 , which are then provided again with a protective mask.

Step 3: The structure is subsequently etched crystallographically-anisotropically in the crystal-oriented sections. The removal of material comes to a standstill as soon as continuous, stable levels protected on all edges are reached. This leads to the in 6a) shown trapezoidal cross-sectional geometry.

• b) Wellenleiterabschnitte mit dem in 6b) beispielhaft gezeigten Kernquerschnitt verlaufen parallel zu in der Waferebene liegenden <110>-Richtungen des Kristallgitters. Sie weisen einen siebeneckigen Querschnitt ABCDEFG auf. Die Strecken AG, BC, EF und ED (Seitenwände) liegen in stabilen {111}-Ebenen der Bauteilschicht, die Strecken AB, CD und FG (Basis- und Deckfläche) in {100}-Ebenen, die durch die unterliegende Schicht 1 bzw. die Maske 3 vor dem Angriff der Ätzlösung geschützt werden. Für die Winkel gilt ∠BAG = ∠CBA ≈ 54.74°, ∠AGF = ∠GFE = ∠EDC = ∠DCB 125.26° und ∠DEF ≈ 70.52°. Die Herstellung erfolgt wie bei der unter 6a) beschriebenen Struktur.
• c) Wellenleiterabschnitte mit dem in 6c) beispielhaft gezeigten Kernquerschnitt verlaufen ebenfalls parallel in der Waferebene liegenden <110>-Richtungen des Kristallgitters. Ihre Querschnittsgeometrie wird durch ein Sechseck ABCDEF beschrieben. Die Strecken BC, CD, EF und AF (Seitenwände) liegen in stabilen {111}-Ebenen der Bauteilschicht, die Strecken AB und DE (Basis- und Deckfläche) in {100}-Ebenen, die durch die unterliegende Schicht 1 bzw. die Maske 3 vor dem Angriff der Ätzlösung geschützt werden. Für die Trapezwinkel gilt ∠CBA = ∠EDC = ∠FED = ∠BAF ≈ 54.74° und ∠BCD = ∠EFA ≈ 109.47°.

Step 4: By a material-selective etching process, for example, the etching mask 3 be removed. Possibly. Thereafter, a new etching mask is applied and the underlying layer 1 is removed locally by material-selective etching

• b) waveguide sections with the in 6b) The core cross-section shown as an example run parallel to <110> directions of the crystal lattice lying in the wafer plane. They have a heptagonal cross-section ABCDEFG. Lines AG, BC, EF, and ED (sidewalls) are located in stable {111} planes of the device layer, and the distances AB, CD, and FG (base and cap) in {100} planes passing through the underlying layer 1 or the mask 3 be protected from the attack of the etching solution. For the angles ∠BAG = ∠CBA ≈ 54.74 °, ∠AGF = ∠GFE = ∠EDC = ∠DCB 125.26 ° and ∠DEF ≈ 70.52 °. The production takes place as in the under 6a) described structure.
• c) waveguide sections with the in 6c) The core cross-section shown by way of example likewise runs <110> directions of the crystal lattice lying parallel in the wafer plane. Their cross-sectional geometry is described by a hexagon ABCDEF. The routes BC, CD, EF and AF (sidewalls) lie in stable {111} planes of the device layer, while the distances AB and DE (base and top surfaces) are in {100} planes defined by the underlying layer 1 or the mask 3 be protected from the attack of the etching solution. For the trapeze angle applies ∠CBA = ∠EDC = ∠FED = ∠BAF ≈ 54.74 ° and ∠BCD = ∠EFA ≈ 109.47 °.

to Preparation of this structure will be the steps described above 1-4, for example, as follows:

Step 1: The edges of the etching masks 3 are oriented in the crystal-oriented section substantially parallel to <110> directions of the crystal lattice lying in the wafer plane.

Step 2: The monocrystalline material of the device layer 2 is removed in the unmasked areas of the crystal oriented portion. This can be done, for example, by a dry chemical anisotropic etching process. As a result, for example, structures with vertical or slightly outwardly or inwardly inclined side walls, the cross section is generally given by the trapezoid ABDE.

Step 3: The structure is etched crystallographically-anisotropically. The slightly trapezoidal prestructured waveguide in the crystal-oriented section is attacked from the side until stable <111> planes of the crystal lattice are reached. That leads to the in 6c) shown "butterfly-shaped" cross-section. The side walls thus comprise a plurality of superimposed portions, which are in an angle defined by the crystal lattice to each other.

• d) Wellenleiterabschnitte mit dem in 6d) beispielhaft gezeigten Kernquerschnitt verlaufen wieder parallel zu in der Waferebene liegenden <110>-Richtungen des Kristallgitters. Sie ergeben sich aus der in 6c) gezeigten Struktur, indem diese beispielsweise in Schritt 4 zusätzlich einer von der Oberfläche her erfolgenden und mit zunehmender Zeitdauer in die Tiefe vordringenden chemischen Reaktion ausgesetzt wird. Diese Reaktion wandelt das Material der Bauteilschicht in eine die Oberfläche des Kerns bedeckende Schicht 4 der Dicke d um und führt so zur Trennung des ursprünglich einteiligen Wellenleiterkerns 2 in zwei isolierte Teile 2a und 2b. Deren Querschnitte werden durch gleichschenklige Dreiecke GHI bzw. JKL beschrieben. Für die Winkel gilt ∠HGI = ∠IHG = ∠LKJ = ∠JLK ≈ 54.74° und ∠GIH = ∠KJL ≈ 70.53°.
• e) Der in 6e) beispielhaft gezeigte Wellenleiterquerschnitt ergibt sich aus der in 6d) gezeigten Struktur, indem diese beispielsweise in Schritt 4 zusätzlich einem materialselektiven Ätzprozess ausgesetzt wird, der die Oberflächenschicht 4 entfernt. Dadurch wird der obere Teil, der das Dreieck JKL als Querschnitt hat, mechanisch vom Rest abgetrennt, und es verbleibt ein Wellenleiter mit dreieckigem Querschnitt GHI. Für die Winkel gilt ∠HGI = ∠IHG ≈ 54.74° und ∠GIH ≈ 70.53°.
• f) 6f) zeigt Querschnitte weiterer beispielhafter Strukturen, die sich mit dem unter 6c) beschriebenen Verfahren herstellen lassen. Abhängig vom den Größen w_g, h₁ und h₂ ergeben sich beispielsweise benachbarte, jedoch voneinander getrennte Strukturen (6f) links) oder eine zusammenhängende Struktur, die einen in Ausbreitungsrichtung ausgedehnten offenen Hohlraum aufweist (6f) rechts). Die Kristallorientierungen der einzelnen Seitenwände und die Winkel können 6c) und der dazugehörigen Beschreibung entnommen werden. Um eine starke Wechselwirkung des geführten Lichtes mit einem bestimmten Material zu erreichen, kann der entstehende Graben in einem weiteren Schritt mit diesem Material ausgefüllt werden.

Step 4: Through a material-selective etching process, the etching mask 3 be removed. Possibly. In an additional step, an etching mask is applied and the underlying layer 1 locally removed by material selective etching.

• d) waveguide sections with the in 6d) The core cross-section shown by way of example again runs parallel to <110> directions of the crystal lattice lying in the wafer plane. They emerge from the in 6c) In addition, for example, in step 4, it is subjected to a chemical reaction taking place from the surface and penetrating with increasing duration. This reaction converts the material of the device layer into a layer covering the surface of the core 4 the thickness d and thus leads to the separation of the originally one-piece waveguide core 2 in two isolated parts 2a and 2 B , Their cross sections are described by isosceles triangles GHI or JKL. For the angles ∠HGI = ∠IHG = ∠LKJ = ∠JLK ≈ 54.74 ° and ∠GIH = ∠KJL ≈ 70.53 °.
• e) The in 6e) waveguide cross section shown by way of example results from the in 6d) structure shown by, for example, in step 4 is additionally exposed to a material-selective etching process, the surface layer 4 away. Thereby, the upper part having the triangle JKL as a cross section is mechanically separated from the rest, leaving a waveguide having a triangular cross section GHI. For the angles ∠HGI = ∠IHG ≈ 54.74 ° and ∠GIH ≈ 70.53 ° applies.
• f) 6f) shows cross sections of other exemplary structures that are compatible with the 6c) can be produced. Depending on the variables w _g , h ₁ and h ₂ , for example, adjacent but mutually separate structures result ( 6f) left) or a contiguous structure that has an open cavity extending in the propagation direction ( 6f) right). The crystal orientations of the individual sidewalls and the angles can 6c) and the associated description. In order to achieve a strong interaction of the guided light with a certain material, the resulting trench can be filled in a further step with this material.

7 and 8th show examples of different open cavities that can be achieved by analogous transfer of the process steps described for index-guided waveguide in a <100> -oriented device layer.

The in 7 shown open cavity has the shape of a truncated pyramid with a rectangular base. The pyramid is straight and its base is parallel to a {100} plane of the crystal lattice. The side surfaces are {111} planes and enclose with the base an angle of θ ₁ = 54.74 °. Cavities with such forms can be prepared by analogous transfer of the process, which is also used for the production of in 6a) used waveguide cross-section has been used and described there already.

The in 8th shown open cavity has the shape of an octahedron, in which the opposite tips are capped. The fourfold axes of rotation of the (complete) octahedron are perpendicular to <100> planes of the crystal lattice. The side surfaces are {111} planes and enclose with the base an angle of θ ₁ = 54.74 °. Cavities with such forms can be produced, for example, by analogous transfer of the method, which is also used to produce the in 6c) waveguide cross section used verwen det and already described there.

3. Structures in <110> -oriented component layers

9 shows examples of cross-sectional geometries that can be achieved with the method described above for a <110> -oriented device layer in the crystal-oriented section of the waveguide structure.

a), b) The waveguide sections with the in 9a) and b) core cross sections shown by way of example run parallel to <112> directions of the crystal lattice lying in the wafer plane (horizontal and perpendicular to the plane of the drawing). Their cross sections are each described by a rectangle ABCD. The BC and AD sidewalls are located in stable {111} planes of the crystal, the distances AB and CD (base and top surfaces) in a {110} plane through the underlying layer 1 or the mask 3 is protected from the attack of the etching solution. To prepare this structure, the above-described steps 1-4 are carried out, for example, as follows:

Step 1: The edges of the etching masks 3 are oriented in the crystal-oriented section substantially parallel to <112> directions of the crystal lattice lying in the wafer plane.

Step 2: The monocrystalline material 2 in the unmasked areas, all or part of the following may be removed subsequently. This can be done by a dry chemical anisotropic etching process. This creates structures with vertical or slightly outwardly or inwardly inclined side walls.

Step 3: The structure is subsequently etched crystallographically-anisotropically. In the process, material is removed from the side until a stable {111} plane is reached, which passes through the mask from above 3 and from below through the underlying layer 1 is protected. This forms a side wall which is exactly vertical to the substrate or wafer plane. If the sidewalls of the structure created in step 2 were inclined inwardly, the core faces 2 of the resulting waveguide at the end of step 4 has a width which is less than that of the mask 3 so that the etching mask 3 " underestimated ", see 9b) ,

Step 4: Through a material-selective etching process, the etching mask 3 be removed. Possibly. In a further step, an etching mask is applied again and the underlying layer is removed locally by material-selective etching.

• c) waveguide sections with the in 9c) The core cross-section shown by way of example likewise runs parallel to the <112> directions of the crystal lattice lying in the wafer plane. They have a substantially rectangular cross-section ABCD, but in contrast to the structures shown under a) and b) have a base region 5 the height h ₂ , in which the material of the component layer 2 was not completely removed. The distances BC and AD (sidewalls) lie in stable {111} planes of the crystal, the distance CD (top surface) in a {110} plane through the mask 3 is protected from the attack of the etching solution. This structure is produced according to the method described under a, b) with the difference that the crystallographic-anisotropic etching process is terminated in step 3 before the component layer 2 completely etched through. The remaining pedestal 5 For example, it can be used to electrically contact the waveguide core.
• d) waveguide sections with the in 9d) The core cross-section shown as an example again run parallel to the <112> directions of the crystal lattice lying in the wafer plane. They consist of two separate strips of height h, between which there is a trench or gap of width w _g , whereby the ratio h / w _g can assume large values. With the example shown here, aspect ratios of more than 5 or, depending on the method, even more than 20 can be achieved.

Both side walls of the gap are stable planes of the crystal lattice, are perpendicular to the wafer plane and are almost exactly parallel. With dry chemical processes, it would be at least extremely difficult and expensive to achieve trenches with a similarly high ratio of depth to width (h / w _g ) and comparable precision.

• e) Wellenleiterabschnitte mit dem in 9e) gezeigten Kernquerschnitt verlaufen wiederum parallel zu in der Waferebene liegenden <112>-Richtungen des Kristallgitters. Sie bestehen aus zwei voneinander getrennten Streifen der Höhe h₁, zwischen denen ein Spalt der Breite w_g liegt, wobei das Verhältnis h₁/w_g große Werte annehmen kann. Dies Streifen weisen einen im wesentlichen rechteckigen Querschnitt auf, besitzen aber im Gegensatz zu der unter d) beschriebenen Struktur einen äußeren Sockelbereich 5 der Höhe oder Dicke h₂, in dem das Material der Bauteilschicht nicht vollständig entfernt wurde. Die Herstellung ist für die Schritte 1 und 2 mit dem unter a/b) beschriebenen Verfahren identisch. Dann erfolgt ein zweistufiger kristallographisch-anisotroper Ätzprozess, bei dem die Bauteilschicht teilweise ganz, teilweise aber nur bis auf den Sockel der Höhe h₂ entfernt wird. Die Herstellung umfasst dann beispielsweise die folgenden Schritte:

The preparation of this structure is carried out under the 9a / b). The crystal orientations of the individual sidewalls can 9a / b) and the corresponding description.

• e) waveguide sections with the in 9e) shown core cross section in turn run parallel to lying in the wafer plane <112> directions of the crystal lattice. They consist of two separate strips of height h ₁ , between which there is a gap of width w _g , wherein the ratio h ₁ / w _g can assume large values. These strips have a substantially rectangular cross-section, but in contrast to the structure described under d) have an outer base region 5 the height or thickness h ₂ in which the material of the device layer has not been completely removed. The preparation is identical for steps 1 and 2 with the process described under a / b). Then a two-step crystallographic-anisotropic etch Process in which the component layer is partially completely, but only partially removed to the base of the height h ₂ . The manufacture then includes, for example, the following steps:

step 1: see under a / b)

step 2: see under a / b)

Step 3: The structure is subsequently etched crystallographically-anisotropically until only one base of the thickness h ₂ remains of the component layer. Then the base area is partially covered with a mask. In the unprotected areas, in particular in the trenches between the waveguide ribs, the remaining material of the component layer is removed in a further crystallographic-anisotropic etching process. Both sidewalls of the waveguide and the trench are now stable planes of the crystal lattice. They are perpendicular to the wafer plane and are exactly parallel. The remaining pedestal areas 5 can be used to the two parts of the waveguide core 2 to contact electrically.

Step 4: Through a material-selective etching process, the etching masks 3 be removed. Possibly. In a further step, an etching mask is applied again and the underlying layer is removed locally by material-selective etching.

10 shows an example of a spatially-shaped open cavity, which can be produced by analogous transmission of the process steps described for index-guided waveguide in a <110> -oriented device layer. It has the shape of a parallelogram-shaped prism parallel to a {110} plane of the crystal lattice. The parallelogram has two internal angles of θ ₂ = 70.53 °. The faces are {111} planes and are perpendicular to the base. Cavities with such forms can be produced, for example, by analogous transfer of the method, which is also used to produce the in 9a) used waveguide and has already been described there.

4. Structures in <111> -oriented component layers

• a) Wellenleiterabschnitte mit dem in 11a) beispielhaft gezeigten Kernquerschnitt verlaufen parallel zu in der Waferebene liegenden <110>-Richtungen des Kristallgitters. Die Querschnittsgeometrie wird durch ein Parallelogramm ABCD beschrieben. Alle Seitenwände liegen in stabilen {111}-Ebenen des Kristalls. Die konvexen Eckpunkte A, B, C und D werden durch die unterliegende Substratschicht 1 bzw. die Maske 3 vor dem Angriff der Ätzlösung geschützt. Für die Winkel gilt ∠CBA = ∠ADC ≈ 109.47° und ∠BAD = ∠DCB 70.53°.

11 shows examples of cross-sectional geometries that can be achieved with the method claimed here for a <111> -oriented device layer in the crystal-oriented section of the waveguide structure. Since the surface of the component layer itself is a stable plane of the crystal lattice, pre-structuring is carried out in step 2. The geometric properties of the obtained waveguides and the respective manufacturing method will be described below.

• a) waveguide sections with the in 11a) The core cross-section shown as an example run parallel to <110> directions of the crystal lattice lying in the wafer plane. The cross-sectional geometry is described by a parallelogram ABCD. All sidewalls lie in stable {111} planes of the crystal. The convex vertices A, B, C and D are defined by the underlying substrate layer 1 or the mask 3 protected from the attack of the etching solution. For the angles, ∠CBA = ∠ADC ≈ 109.47 ° and ∠BAD = ∠DCB 70.53 °.

For the preparation of this structure, the in section 4 For example, steps 1-4 are performed as follows:

step 1: The edges of the etching masks become crystal-oriented Area parallel to each lying in the wafer plane <110> direction of the crystal lattice oriented.

step 2: The device layer is subsequently in the unmasked areas away. This can be done by a dry or wet chemical anisotropic etching process happen. This creates trapezoidal cross-sections AB'CD 'with vertical, slightly inclined outwards or inwards Sidewalls.

Step 3: The structure is subsequently etched crystallographically-anisotropically. The waveguide rib is removed from the side until a stable {111} plane is reached, which passes through the mask from above 3 and from below through the underlying layer 1 is protected. This is inclined by about 19.47 ° relative to the vertical, and there are the described parallelogram-shaped cross sections. There is an undercut of the etching mask 3 at point D instead.

• b) Wellenleiterabschnitte mit dem in 11b) beispielhaft gezeigten Kernquerschnitt verlaufen parallel zu den in der Waferebene liegenden <110>-Richtungen des Kristallgitters. Sie weisen im wesentlichen den unter a) beschriebenen parallelogrammförmigen Querschnitt ABCD auf, besitzen aber zusätzlich einen Sockelbereich 5 der Höhe h₂, in dem das Material der Bauteilschicht 2 nicht vollständig entfernt wurde. Alle Seitenwände liegen in stabilen {111}-Ebenen des Kristalls; die konvexen Ecken bei D und C werden durch die Maske 3 vor dem Angriff der Ätzlösung geschützt. Die Herstellung dieser Struktur erfolgt weitgehend nach dem unter a) beschriebenen Verfahren mit dem Unterschied, dass in Schritt 2 die Bauteilschicht 2 nicht vollständig entfernt wird, sondern nur bis auf eine Sockelschicht 5 der Dicke h₂. Im Gegensatz zu den in 9c) und e) gezeigten Strukturen ist die Oberfläche dieser Sockelschicht 5 in 11b) selbst eine stabile Kristallebene. Es erfolgt hier also durch den kristallographisch-anisotropen Ätzvorgang kein nennenswerter Abtrag, so dass die Ätzrate und die Ätzzeit weniger kritisch sind. Der Sockel 5 kann beispielsweise dazu genutzt werden, den Wellenleiterkern elektrisch zu kontaktieren.
• c) Wellenleiterabschnitte mit dem in 11c) beispielhaft gezeigten Kernquerschnitt verlaufen wiederum parallel zu den in der Waferebene liegenden <110>-Richtungen des Kristallgitters. Sie bestehen aus zwei voneinander getrennten Streifen der Höhe h, zwischen denen ein Spalt der Breite w_g liegt, wobei das Verhältnis h/w_g große Werte annehmen kann. Beide Seitenwände des Spaltes sind stabile Ebenen des Kristallgitters, sind um ca. 19.47° gegenüber der Vertikalen geneigt und sind exakt parallel. Eine solche Struktur kann mit vergleichbarer Präzision mit trockenchemischen Verfahren nicht erzeugt werden. Die Herstellung dieser Struktur erfolgt nach dem unter a) beschriebenen Verfahren. Die Kristallorientierungen der einzelnen Seitenwände und die Winkel des parallelogrammförmigen Querschnittes können 11a) und der dazugehörigen Beschreibung entnommen werden.
• d) Wellenleiterabschnitte mit dem in 11d) beispielhaft gezeigten Kernquerschnitt verlaufen wiederum parallel zu in der Waferebene liegenden <110>-Richtungen des Kristallgitters. Sie bestehen aus zwei voneinander getrennten Streifen der Höhe h₁, zwischen denen ein Spalt der Breite w_g liegt, wobei das Verhältnis h₂/w_g große Werte annehmen kann. Diese Streifen den unter a) beschriebenen parallelogrammförmigen Querschnitt auf, besitzen aber im Gegensatz zu der unter c) beschriebenen Struktur einen Sockel 5 der Dicke h₂, in dem das Material der Bauteilschicht 2 nicht vollständig entfernt wurde.

Step 4: Through a material-selective etching process, the etching mask 3 be removed. Possibly. In an additional step, an etching mask is applied and the underlying substrate layer 1 locally removed by material selective etching.

• b) waveguide sections with the in 11b) The core cross-section shown by way of example runs parallel to the <110> directions of the crystal lattice lying in the wafer plane. They essentially have the parallelogram-shaped cross-section ABCD described under a), but additionally have a base region 5 the height h ₂ , in which the material of the component layer 2 was not completely removed. All sidewalls lie in stable {111} planes of the crystal; the convex corners at D and C are going through the mask 3 protected from the attack of the etching solution. The preparation of this structure is carried out largely according to the method described under a) the difference is that in step 2 the component layer 2 not completely removed, but only up to a base layer 5 the thickness h ₂ . Unlike the in 9c) and e) shown structures is the surface of this base layer 5 in 11b) even a stable crystal plane. Thus, no appreciable removal takes place here by the crystallographic-anisotropic etching process, so that the etching rate and the etching time are less critical. The base 5 For example, it can be used to electrically contact the waveguide core.
• c) waveguide sections with the in 11c) The core cross-section shown as an example again run parallel to the <110> directions of the crystal lattice lying in the wafer plane. They consist of two separate strips of height h, between which there is a gap of width w _g , whereby the ratio h / w _g can assume large values. Both side walls of the gap are stable planes of the crystal lattice, are inclined at about 19.47 ° to the vertical and are exactly parallel. Such a structure can not be produced with comparable precision by dry chemical methods. The preparation of this structure is carried out according to the method described under a). The crystal orientations of the individual side walls and the angles of the parallelogram-shaped cross section can 11a) and the associated description.
• d) waveguide sections with the in 11d) The core cross-section shown by way of example in turn extend parallel to <110> directions of the crystal lattice lying in the wafer plane. They consist of two separate strips of height h ₁ , between which there is a gap of width w _g , whereby the ratio h ₂ / w _g can assume large values. These strips have the parallelogram-shaped cross-section described under a), but have a base, in contrast to the structure described under c) 5 the thickness h ₂ , in which the material of the component layer 2 was not completely removed.

One exemplary manufacturing process gives way for step 2 from the method described under a):

step 1: see under a)

Step 2: The monocrystalline material in the unmasked areas is partially removed until from the device layer 2 only one base of thickness h _{2 is} left. This can be done by a dry chemical anisotropic etching process. This results in approximately trapezoidal cross sections with vertical, slightly outwardly or inwardly inclined side walls.

Step 3: First, a crystallographic-anisotropic etching process is employed, with two ribs similar to those in FIG 11b) shown structure are generated. Then the pedestal area 5 covered with a mask that leaves the ditch between the waveguide ribs. In the unprotected areas, the residual material of the device layer is formed by a non-crystallographic anisotropic etching process 2 away. Another crystallographic-anisotropic etching finally gives the cross section shown.

Step 4: see under a)
The remaining pedestal areas 5 For example, they can be used to electrically contact the two parts of the waveguide core.

12 FIG. 4 shows an example of an open cavity formed by analogously transferring the process steps described for index-guided waveguides to a <111> -oriented device layer 2 can be produced. The bases of such cavities are three- to six-sided polygons whose internal angle can be about 60 ° and / or about 120 °. The same applies to the top surface. They are both parallel to a {111} plane of the crystal lattice. The side surfaces are {111} planes and enclose angles of θ ₃ = 70.53 ° with the top and bottom surfaces. Cavities with such forms can be produced, for example, by analogous transfer of the method, which is also used to produce the in 11a) used waveguide and has already been described there. Since the surface of the device layer itself is a stable plane of the crystal lattice, in step 2 a dry or wet chemical anisotropic etch step is necessary to pre-mold the cavity. The crystallographic-anisotropic etching process then performs as in 12 indicated to undercut the mask 3 on certain edges.

It is obvious to the person skilled in the art that the embodiments described above are exemplary for <100>, <110> and <111> -oriented component layers and do not claim to be complete. By a suitable variation of the described process steps, further structures can be produced with shapes that are incorporated into the 6 to 12 not shown. As can be seen, the method is particularly suitable for the production of cavities and photonic crystals as such.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• US 2002/0031321 A1 [0008, 0010]
• US 2005/0013575 A1 [0008, 0010, 0010]

Cited non-patent literature

• Joannopoulos, Photonic Crystals: Molding the Flow of Light, Princeton University Press, ISBN: 0-691-03744-2, Jul. 1995) [0003]
• Almeida et al., Guiding and confining light in void nanostructure, Opt. Lett. 29 (11), p. 1211ff, 2004 [0004]
• Seidel et al., Anisotropic Etching of Crystalline Silicon in Alkaline Solutions, J. Electrochem. Soc. 137 (11), p. 3612ff, 1990 [0010]
• Tabata et al., Anisotropic etching of silicon in TMAH solutions, Sensors and Actuators A 34, p. 51 et seq., 1992 [0010]

Claims (59)

Multi-stage process for the production of components with an optical waveguide structure ( 30 . 130 ) of not exclusively simple cylindrical shape and with at least partially precisely defined side surfaces ( 72a . 72b . 74a . 74b using a crystallographic-anisotropic etching method, comprising the following steps: (a) providing a multilayer substrate with a mechanically stable carrier layer ( 1 ) and a monocrystalline layer ( 2 ) of a high refractive index material, wherein the monocrystalline layer ( 2 ) as a component layer for the subsequent structuring of the waveguide structure ( 30 . 130 ), (b) dividing the monocrystalline component layer into at least a first region ( 10a . 10b ) for a crystal-oriented or non-crystal-oriented first section of the waveguide structure ( 30 . 130 ) and at least a second area ( 11a . 11b . 11c ) for a crystal-oriented second section of the waveguide structure ( 30 . 130 ), (c) structuring the monocrystalline component layer ( 2 ) in a first etching step by means of at least on the first region ( 10a . 10b ) of the monocrystalline component layer ( 2 ) applied structured etching mask ( 3 In the first etching step, at least the first section of the waveguide structure in the first region (FIG. 10a . 10b ) from the monocrystalline component layer ( 2 ), (d) structuring the monocrystalline component layer ( 2 ) in a second etching step by means of at least on the second region ( 11a . 11b . 11c ) of the monocrystalline component layer ( 2 ) applied structured etching mask ( 3 In the second etching step, the second section of the waveguide structure in the second region (FIG. 11a . 11b . 11c ) from the monocrystalline component layer ( 2 ), wherein in the second etching step a crystallographic-anisotropic etching method is applied, by means of which in the second area ( 11a . 11b . 11c ) crystal-oriented side surfaces running parallel to stable planes of the crystal ( 72a . 72b . 74a . 74b ) of the second section of the waveguide structure, wherein in the first etching step ( 86a . 86b . 94a . 94b . 182a . 182b . 194a . 194b ) at least one side surface of the first waveguide section is generated such that it does not extend parallel to any of the crystal-oriented side surfaces of the second section of the waveguide structure. Method according to claim 1, characterized in that during the second etching step the first region ( 10a . 10b ) by means of a protective mask ( 8th ) to etch the device layer ( 2 ) in the first area. Method according to claim 2, characterized in that the structured etching mask ( 3 ) is applied for the first and second area in one step and the protective mask ( 8th ) for the first area after the patterned etch mask ( 3 ) and the first area ( 10a . 10b ) including the structured etching mask ( 3 ) in the first region during the second etching step through the protective mask ( 8th ) is etched resistant. Method according to one of the preceding claims, characterized in that during the first etching step the second region ( 11a . 11b . 11c ) by means of a protective mask ( 7 ) to prevent etching of the device layer in the second region. Method according to claim 4, characterized in that the structured etching mask ( 3 ) is applied for the first and second area in one step and the protective mask ( 7 ) for the second area after the patterned etch mask ( 3 ) and the second area ( 11a . 11b . 11c ) including the structured etching mask ( 3 ) in the second region during the first etching step through the protective mask ( 7 ) is etched resistant. Method according to one of the preceding claims, characterized in that at least some of the following steps are carried out in the following order: application of the structured etching mask ( 3 ) in the first and second areas ( 10a . 10b . 11a . 11b . 11c ), subsequently covering the second area ( 11a . 11b . 11c ) with a protective mask ( 7 ), subsequently etching the first region ( 10a . 10b ) by means of the structured etching mask ( 3 ) in the first etching step for producing the first portion of the waveguide structure, the second region being formed by means of the protective mask (FIG. 7 ) etch-resistant, subsequently removing the protective mask ( 7 ) in the second area and covering the first area with a protective mask ( 8th ), followed by crystallographic anisotropic etching of the second region ( 11a . 11b . 11c ) by means of the structured etching mask ( 3 in the second etching step for producing the second section of the waveguide structure, subsequently removing the protective mask ( 8th ) and optionally the structured etching mask ( 3 ). Method according to one of the preceding claims, characterized in that at least some of the following steps are carried out in the following order: application of the structured etching mask ( 3 ) in the first and second areas ( 10a . 10b . 11a . 11b . 11c ), subsequently etching the first and second regions by means of the structured etching mask (US Pat. 3 ) in the first etching step for producing the first portion and for preforming the second portion of the waveguide structure, subsequently covering the first area (FIG. 10a . 10b ) with a protective mask ( 8th ), followed by crystallographic anisotropic etching of the second region ( 11a . 11b . 11c ) with the second etching step for producing the second section of the waveguide structure having at least one side surface ( 72a . 72b . 74a . 74b ) which is crystal-oriented parallel to a stable crystal plane and subsequently removing the protective mask ( 8th ) and optionally the structured etching mask ( 3 ). Method according to one of the preceding claims, characterized in that in the first etching step and the first region ( 10a . 10b ) the waveguide structure in the form of a waveguide core ( 82 . 84 . 86 . 94 . 92 . 96 . 182 . 194 ) as an optical lead or as an optical connection for the second region ( 116 ) is produced. Method according to one of the preceding claims, characterized in that in the second etching step the second portion of the waveguide structure in the form of a cylindrical waveguide core ( 42 . 44 . 52 . 54 . 60 . 70 . 140 ) and formed with a polygonal cross-section, wherein at least one of the side walls (2) produced in the second etching step ( 72a . 72b . 74a . 74b ) of the waveguide core ( 60 . 70 ) parallel to a stable crystal plane of the device layer ( 2 ) runs. Method according to claim 9, characterized in that the first section of the waveguide structure comprises a waveguide core ( 84 . 86 . 94 . 96 . 182 . 194 ), which has a uniform cross-sectional shape in the direction of propagation ( 84 . 86 . 94 . 96 ) generated by the cross-sectional shape of the cylindrical polygonal waveguide core ( 60 . 70 ) in the second section, or in one direction ( 84 . 86 . 94 . 96 ) extending from the direction of the cylindrical waveguide core ( 60 . 70 ) deviates in the second section, or along the propagation direction a curved curve ( 84 . 86 . 94 . 96 . 194 ) or changes its direction stepwise or abruptly, or its cross section in propagation direction continuously ( 182 ), gradually or abruptly changes. Method according to one of the preceding claims, characterized in that the second section of the waveguide structure has an upwardly open trench (FIG. 66 . 76 ), wherein the trench has a polygonal cross-section and at least one side wall ( 72b . 74a ) of the trench parallel to a stable crystal plane of the device layer ( 2 ) runs. A method according to claim 11, characterized in that the second portion of the waveguide structure in the form of a multi-part waveguide core ( 60 . 70 ) having at least a first and a second core strip ( 62 . 64 . 72 . 74 ), wherein the upwardly open trench ( 66 . 76 ) is arranged between the core strips. Method according to one of the preceding claims, characterized in that the second section of the waveguide structure has a plurality of polyhedron-shaped cavities arranged along the propagation direction of the light ( 160 ) in the monocrystalline component layer ( 2 ), wherein at least one side surface of the cavities is parallel to a stable crystal plane of the monocrystalline material. Method according to one of the preceding claims, characterized in that for the first etching step used a non-crystallographic-anisotropic etching process becomes. Method according to one of the preceding claims, characterized in that after the generation of the waveguide structure ( 30 . 130 ) a low-refraction surrounding material around the waveguide structure at least in the second region ( 11a . 11b . 11c ) is applied to the device. Method according to one of the preceding claims, characterized in that after the structuring of the second portion of the waveguide structure, a chemical reaction takes place from the surface and penetrates with increasing duration so that this reaction leads to originally contiguous areas of the material decompose the component layer into isolated subregions, which are separated by the reaction products ( 4 ) are separated from each other. Process according to claim 16, characterized in that the reaction products ( 4 ) are removed by a material-selective etching process and thereby in the material of the monocrystalline component layer isolated portions arise or parts of the material of the monocrystalline component layer are mechanically separated. Method according to claim 16 or 17, characterized that which takes place from the surface and with increasing Depth of time penetrating chemical reaction an oxidation of the single crystal material. Method according to one of the preceding claims, characterized in that the waveguide structure in the second section comprises a single- or multi-part waveguide core and the material of the device layer in at least one the waveguide core adjacent area is not completely removed and there is connected to the waveguide core pedestal area ( 5 ) remains. Method according to one of the preceding claims, characterized in that the monocrystalline component layer a Diamond or zinc blende has. Method according to one of the preceding claims, characterized in that a crystallographic anisotropic etching process is used in which the stable crystal planes {111} planes are. Method according to one of the preceding claims, characterized in that a monocrystalline silicon layer as a component layer ( 2 ) is used. Method according to one of the preceding claims, characterized in that for the crystallographic-anisotropic etching method, a liquid etchant is used which contains OH ^- ions in aqueous solution. Method according to one of the preceding claims, characterized in that a crystallographic <100> direction of the component layer ( 2 ) is oriented perpendicular to the substrate plane. Method according to one of the preceding claims, characterized in that in the second region a waveguide core ( 72a . 72b . 74a . 74b ), whose sidewalls enclose an angle of about 54.74 ° with the plane of the substrate. Method according to one of claims 1 to 23, characterized in that a crystallographic <110> direction of the component layer ( 2 ) is oriented perpendicular to the substrate plane. Method according to one of the preceding claims, characterized in that in the second region a waveguide core ( 60 . 70 ) is structured, whose side walls are perpendicular to the substrate plane. Method according to one of claims 1 to 23, characterized in that a crystallographic <111> direction of the device layer oriented perpendicular to the substrate plane. Method according to one of the preceding claims, characterized in that in the second region a waveguide core ( 60 . 70 ), whose sidewalls enclose an angle of about 70.53 ° with the plane of the substrate. Optical waveguide device with one on a carrier substrate ( 1 ) applied highly refractive waveguide structure ( 30 . 130 ) of monocrystalline material ( 2 ) and of not exclusively simple cylindrical shape with at least partially precisely defined side surfaces ( 72a . 72b . 74a . 74b ), wherein the waveguide structure ( 30 . 130 ) in at least one crystal-oriented or non-crystal-oriented first section ( 10a . 10b ) and a crystal-oriented second section ( 11a . 11b . 11c) is divided and the waveguide structure in the first and second sections along the surface of the carrier substrate ( 1 ) for guiding light through the first and second sections, wherein at least one side surface ( 72a . 72b . 74a . 74b ) of the waveguide structure in the second section ( 11a . 11b . 11c ) is crystal-oriented parallel to a stable crystal plane, and at least one side surface ( 86a . 86b . 94a . 94b . 182a . 182b ) of the waveguide structure in the first section ( 10a . 10b ) to none of the crystal-oriented side surfaces ( 72a . 72b . 74a . 74b ) of the waveguide structure in the second section ( 11a . 11b . 11c ) is parallel. Optical waveguide component according to claim 30, characterized in that the waveguide structure in the first section as an optical lead ( 82 . 84 . 86 . 92 . 94 . 96 . 182 . 194 ) or connection for the second section ( 11a . 11b . 11c ) serves. Optical waveguide component according to one of the preceding claims, characterized in that the waveguide structure ( 30 . 130 ) in the second portion comprises a waveguide core having a cylindrical shape with a polygonal cross-section, wherein at least one of the side walls ( 72a . 72b . 74a . 74b ) of the waveguide core is parallel to a stable crystal plane of the device layer. Optical waveguide device according to claim 31 or 32, characterized in that the waveguide core in the first section ( 10a . 10b ) a different cross-sectional shape than in the second ( 11a . 11b . 11c ) Section or at least piecewise in another direction ( 84 . 86 . 94 . 96 . 194 ) than in the second section or tapers ( 182 ) or the waveguide core in the first section along the propagation of the light a curve ( 84 . 86 . 94 . 96 . 194 ) describes. Optical waveguide component according to one of the preceding claims, characterized in that the side surfaces of the waveguide structure ( 30 . 130 ) in the second section one characterized by the location of the stable crystal planes defined inclination to the substrate surface. Optical waveguide component according to one of the preceding claims, characterized in that the waveguide structure ( 30 . 130 ) is surrounded at least in the second region of low-refractive environment material. Optical waveguide device according to Claim 35, characterized in that the low-index surrounding material is an electro-optical material which is in line with the waveguide structure (10). 30 . 130 ) guided light interacts. Optical waveguide device according to claim 35 or 36, characterized in that the low-refractive environment material special glasses, in particular lead glasses, halide or chalcogenide glasses, tellurium oxide glasses, Bismuth oxide-containing glasses or doped or undoped semiconductor compounds contains. Optical waveguide device according to one of Claims 35 to 37, characterized in that the low-refractive Surrounding material carbon compounds, in particular polymers or Liquid crystals with special optical or electro-optical Features, contains. Optical waveguide device according to one of Claims 35 to 38, characterized in that the low-refractive Surrounding material additional structures on a size scale below the wavelength of light in this material. Optical waveguide device according to one of Claims 35 to 39, characterized in that the low-refractive Environmental material for generation, reinforcement, absorption or detection of light is suitable. Optical waveguide device according to one of Claims 35 to 40, characterized in that the interaction of the light with the surrounding material non-linear optical effects causes. Optical waveguide device according to one of the preceding claims, characterized in that the second section of the waveguide structure ( 30 . 130 ) an upwardly open trench ( 66 . 76 ), wherein the trench has a polygonal cross section and at least one side wall of the trench ( 72b . 74a ) runs parallel to a stable crystal plane of the device layer. An optical waveguide device according to claim 42, characterized in that the second portion of the waveguide structure comprises a multi-part waveguide core ( 60 . 70 ) having at least a first and a second core strip ( 62 . 64 . 72 . 74 ), wherein the upwardly open trench ( 66 . 76 ) are arranged between the core strips. Optical waveguide component according to claim 42 or 43, characterized in that the trench ( 66 . 76 ) is at least partially filled with the surrounding material. Optical waveguide device according to one of the preceding claims, characterized in that the waveguide structure in the second section comprises a waveguide core and the monocrystalline material ( 2 ) is not completely removed in at least one region adjoining the waveguide core and there is one with the waveguide core ( 60 . 70 ) ( 5 ). An optical waveguide device according to claim 45, characterized in that the waveguide core extends over the pedestal region (FIG. 5 ) is electrically contactable. Optical waveguide device according to one of the preceding claims, characterized in that the waveguide structure in the second section (FIG. 11a . 11b . 11c ) comprises a waveguide core and the waveguide core at least in sections has a width which is less than the wavelength of the light to be led in the core material. Optical waveguide component according to one of the preceding claims, characterized in that the second section of the waveguide structure has a plurality of polyhedron-shaped cavities arranged along the propagation direction of the light ( 160 ) in the monocrystalline device layer, wherein at least one side surface of the cavities ( 160 ) runs parallel to a stable crystal plane of the monocrystalline material. Optical waveguide component according to Claim 48, characterized in that the polyhedral cavities ( 160 ) are filled with the low-refractive material. Optical waveguide component according to claim 48 or 49, characterized in that the open cavities ( 160 ) are arranged in the second section so as to generate multiple reflections of the guided light, so as to inhibit the propagation of light of particular wavelengths in those areas. Optical waveguide component according to one of the preceding claims, characterized gekenn records that the monocrystalline material ( 2 ) has a diamond or zinc blende grating. Optical waveguide device according to one of preceding claims, characterized in that the stable crystal planes {111} planes of the crystal are. Optical waveguide component according to one of the preceding claims, characterized in that the monocrystalline material ( 2 ) consists of monocrystalline silicon. Optical waveguide device according to one of preceding claims, characterized in that a crystallographic <100> direction of the monocrystalline Material is oriented perpendicular to the substrate plane. Optical waveguide device according to one of preceding claims, characterized in that the second section of the waveguide structure a waveguide core includes, whose side walls with the substrate plane a Include angles of about 54.74 °. Optical waveguide component according to one of Claims 30 to 53, characterized in that a crystallographic <110> -direction of the monocrystalline material ( 2 ) is oriented perpendicular to the substrate plane. Optical waveguide device according to one of preceding claims, characterized in that the second section of the waveguide structure a waveguide core comprises, whose side walls perpendicular to the substrate plane run. Optical waveguide component according to one of Claims 30 to 53, characterized in that a crystallographic <111> -direction of the monocrystalline material ( 2 ) is oriented perpendicular to the substrate plane. Optical waveguide device according to one of preceding claims, characterized in that in the second region is a waveguide core is structured, the Side walls with the substrate plane at an angle of about 70.53 °.