Glasses for local index modification by ion exchange and devices comprising the same

Abstract

The invention provides a glass or a glass substrate with constituent phases which enable the introduction of waveguides by ion exchange, wherein the thermal expansion coefficient is advantageously at most 8ppm / K, especially from 2.5ppm / K to 8ppm / K. The glass therefore is especially suitable for the combination with semiconductor devices or substrates, e.g. for the production of an electronic or optoelectronic devices.

Description

[0001] Glasses for Local Index Modification by Ion Exchange and Devices comprising the same

[0002] The invention refers to glasses which combine suitability for local index modification by ion exchange with a thermal expansion, advantageously matching to that of semiconductor materials such as silicon, i.e. a comparatively low thermal expansion coefficient (CTE), and devices incorporating those glasses, especially devices comprising the glass and a semiconductor element.

[0003] State of the Art

[0004] If a glass is suitable for ion exchange, this feature is usually exploited not for index modification but for chemical prestressing, i.e., the glass, in most cases a glass sheet, is furnished with surface layers characterized by strong compressive stress and an interior layer with a mild tensile stress. Such glass products are less sensitive to mechanical impact.

[0005] The most common glasses for that purpose have a high sodium content, which is partially or completely replaced with potassium ions in the surface during prestressing. As the potassium ions are bigger than the sodium ions, their space requirement is bigger than the one of the latter. As a consequence, they try to stretch the material. This causes tensile stress in the interior layer where the sodium ions have not been replaced with potassium ions. The interior layer strikes back and brings the surface layers under compressive stress, as desired. As the ion exchange is carried out at high temperatures, yet at temperatures significantly below the glass transition range, only a small part of these stresses relax during the process so that a glass sheet with permanent compressive stress at the surface results. As both the suitability for ion exchange and the thermal expansion coefficient have the tendency to rise with rising sodium content, such glasses usually have high coefficients of thermal expansion. This is advantageous for the meltability because the temperature range, at which the viscosity of the glass is low enough for melting and hot forming, inversely scales with the thermal expansion. It is disadvantageous for combing with semiconductor materials the thermal expansion coefficients of which are usually significantly lower.

[0006] To give an example. US 2013 / 0165312 A1 describes cover glasses for semiconductor applications, which are suitable for ion exchange and characterized by a high content of alkaline as well as alkaline earth oxides as well as a very high thermal expansion, 9 - 18 ppm / K according to claim 1 . Compare with thermal coefficient of silicon which is about 3 ppm / K in the range 20 - 300°C.

[0007] Object

[0008] In the state of the art, there is a lack of glasses that combine suitability for local index modification by ion exchange with an advantageous thermal expansion and a working point that is well suited for production. In addition, it should be possible to manufacture the glasses using modem flat glass production methods.

[0009] The goal of the invention is to provide glass substrates, which are suitable for the following process: the negative pattern of a structured protective layer on top of the substrate is transferred into the latter by ion exchange. By selecting suitable ions for the ion exchange, the refractive index of the glass is increased in the lines defined by said pattern. These lines are supposed to serve as waveguide cores.

[0010] The object is solved by the subject-matter of this description and the patent claims. Advantageous embodiments can be derived from the dependent claims. Description of the invention

[0011] The object is solved by a specific combination of stoichiometric glasses, i.e. glasses which exist in the same stoichiometry also as crystals and whose properties can be assumed to be very similar for both glass and crystal because of the identical topology of the assemblies - as verified in the literature in many examples by NMR measurements or the like. For this purpose, such stoichiometric glasses are selected whose mixture makes a behavior in the sense of a solution of the object according to the invention attainable. In this application, these stoichiometric glasses are also referred to as "constituent phases".

[0012] It is not a new concept to describe glasses on the basis of the constituent phases to be assigned to them. By specifying the constituent phases, conclusions can be drawn about the chemical structure of a glass (see Conradt R: "Chemical structure, medium range order, and crystalline reference state of multicomponent oxide liquids and glasses", in Journal of Non-Crystalline Solids, Volumes 345-346, 15 October 2004, Pages 16-23).

[0013] In one aspect, the invention relates to a glass having the following combination of constituent phases:

[0014] Table 1

[0015] The composition is chosen with regard to the phases constituting the glass within the limits described herein. The phases constituting the glass are, of course, not present as such in the glass product in crystalline, but amorphous form. This does not mean, however, that the constituent phases have completely different building units in the amorphous state than in the crystalline state. As stated above, the topology of the building units is comparable, e.g., the coordination of the cations involved with surrounding oxygen atoms or the interatomic distance resulting from the coordination and the strength of the bond between these cations and surrounding oxygen atoms. Therefore, many properties of the glass of the invention can be well described on the basis of the constituent phases, in particular to illustrate the inventive achievement and the problems overcome by the invention.

[0016] Of course, the glass can be produced not only by using the corresponding crystals, but also by using the usual glass raw materials, as long as only the stoichiometric ratios allow the formation of the corresponding building blocks of the constituent phases. Suitability for local index modification by ion exchange (sodium for silver)

[0017] The suitability for local index modification by exchanging sodium ions for silver ions is made sure by a significant fraction of building units which contain highly mobile sodium ions in the glasses according to the invention.

[0018] Coefficient of thermal expansion according to ISO 7991

[0019] Surprisingly, the position of the thermal expansion coefficient (CTE) according to ISO 7991 in the target range can also be represented with the aid of a very simple calculation rule. This is obtained via the average bond strength.

[0020] It is known in the art that the coefficient of thermal expansion for metals, for example, is inversely proportional to the binding energy (or to the "depth of the interatomic potential wells").

[0021] In an abstract picture of oxidic glasses, the cations are placed in a potential well formed by the surrounding oxygen atoms and the depth of the potential well is assumed to be the sum of the bond strengths of the various single bonds to the surrounding oxygen atoms, i.e. the entire interaction energy is concentrated in potential wells with the cations in the center and the oxygen atoms in the periphery.

[0022] Thus, the reverse case needs no longer be considered; it would also be more difficult to analyze, since an oxygen atom can be located between several different types of cations, which conversely cannot occur in purely oxide glasses. These values are tabulated, e.g. in DE 10 2014 119 594 A1 :

[0023] Table 2

[0024] The values for Zr, Nb, and Zn are not from DE 10 2014 119 594 A1 , but are calculated using exactly the same method described there from the values given in Standard Thermodynamic Values at 25°C, retrieved from the literature.

[0025] From the composition of a glass of the constituent phases given above, the numbers of different cations contained in the respective phases, and the potential well depths per cation tabulated above, a mean potential well depth Epotcan can be calculated:

[0026] Where m is the number of cation types occurring in each constituent phase (the numerical value of m depends on the constituent phase), Epotj is the potential well depth tabulated above for the j-th cation type, and Zj is the number of cations of the j-th type in the i-th constituent phase. The sums over j are tabulated below:

[0027] Table 3

[0028] This average bond strength is inversely proportional to the coefficient of thermal expansion, as is the case for metals. Evaluation of a number of different glasses, including commercial glasses such as Borofloat33, Borofloat40, AF45, AF32 leads to the following formula:

[0029] Since the bond strength is inversely proportional to the melting point, an inverse proportionality also applies between the melting point and the coefficient of expansion. Since the melting point is not precisely defined for non-stoichiometric glasses, only a tendential relationship applies between a typical temperature for the melting and hotforming range, e.g., the working point, at which the viscosity is 104dPa s, and the coefficient of expansion. However, via this tendential relationship makes it clear that the combination of low coefficient of thermal expansion and an upper limit for the working point is challenging, especially if the glass is simultaneously supposed to have a high sodium fraction, which favours a low working point but does not favour a low coefficient of thermal expansion.

[0030] With respect to the interferometric effects, coupling of neighbouring structures etc. the thermal expansion coefficient of the glass should be made small, preferably as close as possible to the one of silicon in order to suppress any negative effect caused by an expansion mismatch. Therefore, the thermal expansion coefficient (CTE) of the glass is preferred to be at most 8 ppm / K, more preferably at most 7.5 ppm / K, more preferably at most 7 ppm / K, more preferably at most 6.75 ppm / K, more preferably at most 6.5 ppm / K, more preferably at most 6.25 ppm / K, more preferably at most 6.0 ppm / K, more preferably at most 5.75 ppm / K, more preferably at most 5.5 ppm / K, more preferably at most 5.25 ppm / K, more preferably at most 5.0 ppm / K, more preferably at most 4.75 ppm / K, more preferably at most 4.5 ppm / K, more preferably at most 4.25 ppm / K, more preferably at most 4.0 ppm / K, more preferably at most 3.75 ppm / K, more preferably at most 3.5 ppm / K. In some embodiments, the CTE is at least 2.50 ppm / K, at least 2.75 ppm / K, at least 3.00 ppm / K, at least 3.25 ppm / K, or at least 3.50 ppm / K. This refers to the value CTE, which can be calculated using formula (2) for glasses of this invention.

[0031] In order to identify an optimum trade-off between the above three properties, a highly precise calculation tool for the working point is required. Viscosity curve, especially working point (WP)

[0032] Surprisingly, a mixing rule can also be given for viscosity of glass, with which the viscosity is calculated from the viscosities of the constituent phases.

[0033] The starting point is the Adam-Gibbs relationship in its formulation for viscosity (see C.A. Angell, Structural Instability and Relaxation in Liquid and Glassy Phases near the fragile liquid limit, Journal of Non-Crystalline Solids 102 (1988) 205-221):: qo is a prefactor. Q is a constant. Sc(T) is the configurational entropy, which according to Hodge is calculated from the configurational fraction ACP(T) of the specific heat (“excess specific heat”) under the assumption ACP(T) = D / T by (see C.A. Angell, loc. cit. , and the literature cited there):

[0034] TK is the Kauzmann temperature, which according to C.A. Angell, loc. cit., is identified with the Vogel-Fulcher-Tammann temperature To. Thus, the Adam-Gibbs relation can be transformed into the Vogel-Fulcher-Tamman equation (VFT equation):

[0035] A, B, To are the parameters of the VFT equation, which are determined by fit to a measurement curve.

[0036] With the assumptions of Angell and Hodge, Adam-Gibbs and VFT correspond to each other. Thus, the parameters qo and D / Q, which are in the Adam-Gibbs relationship, can be calculated from the VFT parameters A, B, To.

[0037] 7]0= IO71dPa ■ s (6a)

[0038] £=Z (6b) Q ~ B From the relationships between Adam-Gibbs and VFT, a mixing rule can be derived that can be used to calculate the VFT parameters of a glass from the VFT parameters of the constituent phases known from measurements.

[0039] The first approach is:

[0040] It is used here that the entropy is an additive quantity and is summed over all constituent phases. The mixture entropy is neglected according to Conradt, loc. cit.

[0041] Vi is the fraction of the i-th constituent phase in atom% rather than in mol%; the fact that atom%s have to be used here follows from the derivation of the Adam- Gibbs equation.

[0042] If in addition, one assumes that Q has one and the same value for all constituent phases as well as the glass formed by mixing them, one can calculate:

[0043] The values for Di or Di / Q refer to the individual constituent phases and are obtained from their VFT parameters A, Bi, To,i according to (6). The sum over “i” is from 1 to n, as above.

[0044] With B and To, two of the three VFT parameters of the glass formed by mixing the constituent phases are known. For the determination of A, it is made use of that the VFT equation approaches an Arrhenius relationship q = 10A+B / Tat high temperatures, and there are several literature references to an approximately linear relationship between A and B for an Arrhenius-conforming viscosity. This leads to the formula:

[0045] "vi" again refers to atomic percentages. The sum over “i” is from 1 to n, as above.

[0046] For the calculation of the VFT parameters of a glass expressed as a mixture of the constituent phases forming the basic system of the invention, the VFT parameters of these phases are required. These are:

[0047] Table 4

[0048] The VFT parameters of silica were obtained by adaptation to the publicly available measurement data. All other VFT parameters were determined in the accredited measuring laboratories of Schott AG in Mainz on specially prepared test samples.

[0049] If A, B, To are known from the formulas (8) - (9), the working point WP is calculated by transforming (5) according to: and the annealing point AP according to:

[0050] For example, mixing the constituent phases SiO2 and B2O3 in a molar ratio of 9 : 1 or 0.9 : 0.1 which is equivalent to an atomic ratio of 9*3 / (9*3+1 *5) : 1 *5 / (9*3+1 *5) (note that SiO2 has 3 atoms whereas B2O3 has 5 atoms), we first obtain according to equation (6b) Dsio2 / Q = (273.2-240.131 )726018.9 = 0.00127 and DB203 / Q = (273.2+149.859) / 1650.5 = 0.25632. From this, the mixture is calculated according to equation (8a) D / Q = (9*3*Dsio2 / Q +1 *5*DB2O3 / Q) / (9*3+1 *5) = 0.04112. From this, the To value of the mixture is calculated according to equation (8b) To =

[0051] 0.04112 / ((9*3 / 26018.9+1 *5 / 1650.5)7(9*3+1 *5)) = 323.533 K, i.e. 50.333°C. According to equation (8c), the B value of the mixture is calculated as 323.533K / 0.04112 = 7868.03K. According to equation (9), A = (9*3*(-6.01651 )726018.9+1 *5*(-

[0052] 0.0871546)71650.04) / ((9*3+1 *5)77868.03) = -1.6. This gives the working point WP as (7868. 03 / 5.6+323.533) K = 1728.54 K, i.e. 1455.34 °C, and the annealing point AP to (7868.03 / 5.6+323.533) K = 862.439 K, i.e. 589.239 °C. With respect to flat glass production, e.g., by drawing, the working point is preferably at most 1400°C, more preferably at most 1390°C, more preferably at most 1380°C, more preferably at most 1370°C, more preferably at most 1360°C, more preferably at most 1350°C, more preferably at most 1340°C, more preferably at most 1330°C, more preferably at most 1320°C, more preferably at most 1310°C, more preferably at most 1300°C, more preferably at most 1290°C, more preferably at most 1280°C, more preferably at most 1270°C, more preferably at most 1260°C, more preferably at most 1250°C.

[0053] Selection of constituent phases

[0054] The selection of constituent phases has been with respect to ion exchangeability, expansion coefficient and working point. By the latter expression, the temperature is addressed where the viscosity value is 104dP s, a typical viscosity for the melting and hot forming range. In the following, the role of the individual constituent phases is discussed in detail.

[0055] Albite

[0056] Glassy albite is one of the constituent phases according to the invention. Albite is a tectosilicate consisting of SiCM- und AICM-tetrahedra with sodium ions which may move in the resulting framework, thus giving rise to a high sodium diffusivity, see Geochimica et Cosmochimica Acta, 1963, Vol. 27, pages 107-120. Therefore, a certain albite fraction is preferred in the glasses according to the invention which is favourable for their ion exchangeability.

[0057] The high working point of molten albite (1567°C), however, is disadvantageous for the glasses according to the invention which makes it necessary to combine albite with other constituent phases.

[0058] There is also another reason to limit the content of Albite together with the one of all other Aluminium-containing phases. Al3+is a small ion of high valence. Under normal conditions, such an ion will be tightly bonded to the neighbouring oxygen atoms by Coulomb interaction. In the acid resistance test, however, the glass surface will be exposed to strong hydrochloric acid. Hydronium ions will penetrate and form an electric double layer together with Chlorid ions sticking to the surface. The resulting electric field will compensate the Coulomb interaction with the neighbouring oxygen ions so that Al3+will become mobile. Due to its small size, it will quickly leave the glass thus enhancing corrosion. (Note that the Aluminium ion is the smallest ion that may be found under such circumstances. Si4+and B3+do not exist, not even in an extremely acidic environment.) So, a high amount of Aluminium - counting the Aluminium from all Aluminium-containing constituent phases - is unfavourable for acid resistance.

[0059] One mole of albite is understood to be one mole of (Na2O Al2O3-6SiO2) / 8.

[0060] Orthoklas

[0061] Glassy Orthoklas is the potassium analogon of albite and another constituent phase according to the invention. As glass compositions which include both sodium and at least a small fraction of potassium are less sensitive to devitrification, a small amount of othoklas may be added to the composition. Concerning thermal expansion (7.6 ppm / K) and working point (1712°C), however, Orthoklas is even more disadvantageous than albite.

[0062] One mole of Orthoklas is understood to be one mole of (K2O Al2O3-6SiO2) / 8.

[0063] Reedmergnerite

[0064] Reedmergnerite is the boron-analogon of Albite. Glassy Reedmergnerite is another constituent phase according to the invention. As glassy Albite, the glass essentially consists of tetrahedra, this time SiO4- and BO4-tetrahedra, with sodium in the interspaces. Due to the higher bonding energy of the B-O-bond compared to the Al- O-bond, however, a closer-meshed structure results. As a consequence, the activation enthalpy of the sodium motion is higher in Reedmergnerite than in Albite. This is usually not favourable for ion motion. There is a big advantage, however, coming with comparatively low working point (1002°C). Mixing a certain fraction of Reedmergnerite to Albite and Orthoklas will lower the working point in a favourable way.

[0065] Concerning the thermal expansion (6.7 ppm / K), there is not a big difference between Albite and Orthoklas on one side and Reedmergnerite on the other.

[0066] One mole of Reedmergnerite is understood to be one mole of (Na2O B2O3-6SiO2) / 8.

[0067] Vlasovite

[0068] Vlasovite is a both sodium and zirconium-containing mineral which is known for the weak fixation and therefore high mobility of the sodium ions in the structure. Therefore, glassy Vlasovite is also chosen as constituent phase.

[0069] Due to the dense packing of the zirconium ion and its environment, vlasovite provides hardly any space for a penetrating hydroxyl ion, which has an extremely advantageous effect on the alkali resistance. It is not so advantageous with regard to hydrolytic and acid resistance. (Zr+4is a small ion of high valence, which according to the above-mentioned considerations, which are also experimentally confirmed with Vlasovite, is unfavorable for acid resistance), so that it is sensibly combined with other phases. Also because of the fact that Zirconium increases the devitrification sensitivity of a glass, the Vlasovite fraction shall be limited in the glasses according to the invention.

[0070] The working point is 1269°C which far below the one of Albite.

[0071] One mole of vlasovite is understood to be one mole of (Na2O ZrO2-4SiO2) / 6.

[0072] Disodium-Zinco-Silicate

[0073] Like Albite, Disodium-Zinco-Silicate consists of tetrahedra, this time this time SiO4- and ZnO4-tetrahedra, with Sodium ions in the interspaces. With respect to the structural similarity to Albite, see K.-F. Hesse, F. Liebau, H. Bohm, Disodium Zin- cosilieate, Na2ZnSi30s, Acta Cryst. 33 (1977), pages 1333-1337, it is similarity suitable for ion exchange, see EP0027736B1 also. With respect to this and with respect to low working point of 902°C, sodium-zinc-silicate is excellently suited as a constituent phase for the glasses according to the invention

[0074] In contrast to albite, Disodium-Zinco-Silicate has only one intermediate ion, which also has only the valence "2". Both are advantageous for acid resistance. Intermediate ions of high valence such as aluminum ("3") have a small ionic radius, which makes them very mobile and allows them to leave the glass network quickly in the acid resistance test, and are replaced by many (in the case of aluminum again "3") hydronium ions in the acid resistance test, which greatly weakens the network. The opposite is true for alkaline resistance. Due to the weaker bonding energy between Zinc and Oxygen, the network is more easily dissolved by penetrating hydroxyl ions at the Albite network.

[0075] According to the invention, one mole of sodium zinc silicate is understood to be one mole of (Na2O ZnO 3SiO2) / 5.

[0076] Potassium-Niobium-Silicate

[0077] Potassium-niobium-silicate is an alternative to Orthoklas as potassium source which is introduced in the glass to suppress devitrification, particularly because of its very low working point of 1039°C.

[0078] It is also a phase which, like vlasovite, offers little space for a penetrating hydroxyl ion due to the dense packing of the niobium ion and its environment, which has an advantageous effect on the alkali resistance, even if the effect is not as pronounced as with vlasovite. On the other hand, it is somewhat more advantageous in terms of acid resistance. Nb+5, like Zr+4, is a small ion of high valence, but it aggregates with hydroxyl groups (Nb(OH)4+) even at very low pH values. One mole of potassium-niobium-silicate is understood to mean one mole of (K2O Nb2O5-4SiO2) / 6.

[0079] All the above phases have in common that they contain alkaline ions which have an increasing effect on thermal axpansion, see table 2 above. This effect is less pronounced if thephases contain alkaline earths. Therefore, further constituent phases will be introduced below which contain alkaline earths rather than alkalines.

[0080] Cordierite

[0081] One mole of cordierite is understood to mean one mole of (2MgO-2AI2O3-5SiO2) / 9.

[0082] Anorthite

[0083] One mole of Anorthite is understood to mean one mole of (CaO AI2O3-2SiO2) / 4.

[0084] SiO2

[0085] To begin with, SiO2is suitable to push down the coefficient of expansion and thus, on balance, to desired values.

[0086] With regard to the annealing point (1128°C) and the working point (2357°C), it is unsuitable as an easily meltable basic system for the glasses according to the invention, only as an admixture.

[0087] B2Q3

[0088] To begin with, B2O3 is suitable to push down the coefficient of expansion and thus, on balance, to desired values.

[0089] Diboron trioxide forms boroxol rings as a constituent phase, which have a favourable effect on the mechanical properties.

[0090] There is another reason to introduce diboron trioxide as a constituent phase in the glass. This shifts the boron / sodium ratio to higher values, which lowers sodium and boron evaporation during melting and hot forming. In view of the above-mentioned hygroscopy alone, diboron trioxide is unsuitable as a basic system for the glasses according to the invention, only as an admixture.

[0091] Further components

[0092] In addition to the components already mentioned, the glass may contain further constituents, referred to herein as "balance". The proportion of balance in the glass according to the invention is preferably at most 5 mol-%, so as not to disturb the glass properties set by careful selection of suitable base glasses. In particularly preferred embodiments, the proportion of balance in the glass is at most 3 mol%, more preferably at most 2 mol% or at most 1 mol% or at most 0.5 mol%. The balance contains in particular oxides which are not contained in the base glasses mentioned herein. Thus, the balance in particular does not contain SiC>2, B2O3, AI2O3, ZrO2, Nb2Os, ZnO, MgO, CaO, Na2O or K2O.

[0093] According to the invention, additions of further simple oxides of so-called "intermediates", i.e. oxides which stand between the network formers such as SiO2 and the network converters such as Na2O, are optionally used as the balance. Although these oxides do not form glasses on their own, they can be incorporated into the network in the aforementioned percentage range. Thus, the balance may contain, in particular, oxides such as TiO2. Ta2Os also belongs to the "intermediates", as can be calculated using the ionic radii.

[0094] When this description states that the glasses are free of a component or constituent phase or do not contain a certain component or constituent phase, it is meant that this component or constituent phase may be present at most as an impurity in the glasses. This means that it is not added in substantial amounts. According to the invention, non-substantial amounts are amounts of less than 500 ppm (molar), preferably less than 300 ppm (molar), particularly preferably less than 100 ppm (molar), even more preferably less than 50 ppm (molar), and most preferably less than 10 ppm (molar). Preferably, the glasses of the present invention are free of lead, arsenic, antimony, and / or cadmium. The total Sodium fraction as being provided by the above Sodium-containing constituent phases is preferably no less than 5mol%, more preferably no less than 5.5mol%, more preferably no less than 6mol%, more preferably no less than

[0095] 6.5mol%, more preferably no less than 7mol%, more preferably no less than

[0096] 7.5mol%, more preferably no less than 8mol%, more preferably no less than

[0097] 8.5mol%, more preferably no less than 9mol%, more preferably no less than

[0098] 9.5mol%, more preferably no less than 10mol%, more preferably no less than 10.5mol%, more preferably no less than 11 mol%, more preferably no less than

[0099] 11 ,5mol%, more preferably no less than 12mol%, more preferably no less than

[0100] 12.5mol%, more preferably no less than 13mol%, more preferably no less than

[0101] 13.5mol%, more preferably no less than 14mol%, more preferably no less than

[0102] 14.5mol%, more preferably no less than 15mol%.

[0103] Other Glass Properties

[0104] The glass according to this invention will preferably be provided as sheet or endless sheet, with a medium thickness of 30pm to 3mm.

[0105] Production

[0106] Also, according to the invention is a method for producing a glass of the present invention, comprising the steps of:

[0107] - Melting the glass raw materials,

[0108] - optionally forming a glass article, in particular a glass sheet, from the molten glass

[0109] - Cooling of the glass.

[0110] Forming the glass may comprise a drawing process or a floating process or an overflow fusion process. Cooling may involve active cooling using a coolant, such as a cooling fluid, or passive cooling. Uses and glass articles

[0111] According to the invention, the glass may be used as substrate glass in an electronic and / or optoelectronic device. It is especially suitable to inscribe waveguides by fs-laser inscription into the glass substrate and / or to mount semiconductor elements on it, including the coupling to semiconductor devices and / or substrates.

[0112] For example, a corresponding glass has a thermal expansion coefficient CTE that is at most 7ppm / K or which ranges especially from 2.5ppm / K to 7ppm / K and wherein preferably the working point is at most 1400°C.

[0113] Another beneficial embodiment foresees that the Sodium fraction is at least 5.0 mol%. Especially, the Sodium fraction is calculated by a matrix represented by aforesaid table 7 of this description.

[0114] The invention also covers a substrate comprising the glass described above, wherein the glass contains an inscribed waveguide and / or wherein the substrate is mounted to a semiconductor device, or the semiconductor device is mounted to a substrate areas comprising the aforesaid glass.

[0115] The invention relates to an electronic or optoelectronic device as well which comprises the glass or the substrate described above.

[0116] Advantageously, the electronic or optoelectronic device according to the invention comprises a semiconductor device or substrate which has a CTE from 2.6 to 3.4 ppm / K and preferably the glass has a CTE from 2.5 to 3.6 ppm / K.

[0117] The method of inscribing a waveguide into a substrate, comprising the steps of providing a fs-laser source and directing a focused laser beam from said fs-laser source onto the substrate, whereas the substrate is selected from a glass described above, is also subject to the invention. Examples

[0118] For comparison with the prior art, we first give a conversion matrix for the mutual conversion of both compositional data.

[0119] The composition in constituent phases is given in the following normalized form for the purpose of conversion:

[0120] Table 5

[0121] The conversion of these compositions into a composition statement in mol% with respect to the following simple oxides ... Table 6

[0122] ... is carried out with the aid of the matrix given here. The composition in mol% with respect to the constituent phases is multiplied as a column vector from the right to the matrix:

[0123] Table 7: Matrix

[0124] As a result of the multiplication of the column vector to the matrix, the composition of the glass in mole percent with respect to simple oxides is obtained.

[0125] Our first example is a glass with the composition:

[0126] Example 1a

[0127]

[0128] Applying the matrix from table 7 gives:

[0129] Example 1 b

[0130] The properties are: 1. The thermal expansion coefficient calculated according to (2) amounts to 5.03 ppm / K.

[0131] 2. The working point calculated according to (10) amounts to 1268°C.

[0132] Our second example is a glass with the composition:

[0133] Example 2a

[0134] Applying the matrix from table 7 results in:

[0135] Example 2b

[0136] The properties are:

[0137] 1. The thermal expansion coefficient calculated according to (2) amounts to 5.04 ppm / K.

[0138] 2. The working point calculated according to (10) amounts to 1267°C.

[0139] Our third example is a glass with the composition:

[0140] Example 3a

[0141] Applying the matrix from table 7 gives:

[0142] Example 3b

[0143] The properties are:

[0144] 1. The thermal expansion coefficient calculated according to (2) amounts to 5.03 ppm / K.

[0145] 2. The working point calculated according to (10) amounts to 1280°C.

[0146] Our fourth example is a glass with the composition:

[0147] Example 4a

[0148] Applying the matrix from table 7 gives:

[0149] Example 4b

[0150] The properties are:

[0151] 1. The thermal expansion coefficient calculated according to (2) amounts to 4.40 ppm / K.

[0152] 2. The working point calculated according to (10) amounts to 1280°C.

[0153] Our fifth example is a glass with the composition:

[0154] Example 5a

[0155] Applying the matrix from table 7 gives:

[0156] Example 5b

[0157] The properties are:

[0158] 1. The thermal expansion coefficient calculated according to (2) amounts to 4.57 ppm / K.

[0159] 2. The working point calculated according to (10) amounts to 1241 °C. Our sixth example is a glass with the composition:

[0160] Example 6a

[0161] The properties are:

[0162] 1. The thermal expansion coefficient calculated according to (2) amounts to 4.60 ppm / K.

[0163] 2. The working point calculated according to (10) amounts to 1254°C.

[0164] Our seventh example is a glass with the composition:

[0165] Example 7a

[0166] Applying the matrix from table 7 gives:

[0167] Example 7b

[0168] The properties are:

[0169] 1. The thermal expansion coefficient calculated according to (2) amounts to 6.03 ppm / K.

[0170] 2. The working point calculated according to (10) amounts to 1230°C.

[0171] Our eighth example is a glass with the composition:

[0172] Example 8a

[0173] Applying the matrix from table 7 gives:

[0174] Example 8b

[0175] The properties are:

[0176] 1. The thermal expansion coefficient calculated according to (2) amounts to 5.89 ppm / K.

[0177] 2. The working point calculated according to (10) amounts to 1270°C. The invention described herein provides the advantage that it provides a glass which fulfills two requirements, first a waveguide can be introduced by ion exchange. Secondly, the glass described herein has a comparably low CTE, so it can be adapted or even matched to the CTE of semiconductor substrate materials, such as silicon. A further advantage is, that the glass can be rationally produced by industrial melting processes.

Claims

Patent Claims1 . Glass comprising the following constituent phases (in mol%):

2. Glass according to claim 1 , wherein the thermal expansion coefficient is at most 8ppm / K, especially from 2.5 ppm / K to 8 ppm / K, and wherein preferably the working point is at most 1400°C.

3. Glass according to at least one of the preceding claims, wherein the Sodium fraction is at least 5.0 mol%.

4. Glass according to claim 3, wherein the Sodium fraction is calculated by a matrix represented by table 7 of the description.

5. Substrate comprising the glass according to at least one of the preceding claims, wherein the glass contains an inscribed waveguide and / or wherein the substrate is mounted to a semiconductor device or substrate at least in an areas comprising the glass.

6. Electronic or optoelectronic device comprising the glass or the substrate according to at least one of the preceding claims.

7. Electronic or optoelectronic device according to claim 6, wherein the semiconductor device or substrate has a CTE from 2.6 to 3.4 ppm / K and preferably the glass has a CTE from 2.5 to 3.6 ppm / K.

8. Method of inscribing a waveguide into a substrate, comprising the steps of providing a fs-laser source and directing a focused laser beam from said fs-laser source onto the substrate, whereas the substrate is selected from a glass according to at least one of the claims 1 to 4.

9. Method of manufacturing an electronic or optoelectronic device, comprising the steps of mounting a semiconductor element to an element comprising the glass according to at least one of the claims 1 to 4.

10. Method of manufacturing an electronic or optoelectronic device comprising a semiconductor element and a glass substrate, comprising the steps of determining the CTE of the semiconductor element, then selecting the CTE of glass of the glass substrate by selecting a composition range of the glass according to at least one of the claims 1 to 4.

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