METHOD FOR INTEGRALLY BONDING A GLASS ELEMENT TO A SUPPORT ELEMENT, AND OPTICAL DEVICE

Abstract

A method of integrally bonding a glass element to a support element, the method comprising a step of inserting at least one contact element into a contact recess in a surface of the support element. In addition, the method comprises a step of placing the glass element on a portion of the contact element which portion protrudes beyond the surface, and a step of locally heating the contact element in order to connect the glass element to the support element via the contact element. The method also comprises a step of coating at least a part of the contact recess with a separating layer prior to the step of insertion.

Claims

1. A method of integrally bonding a glass element to a carrier element, the method comprising: inserting at least one contact element into a contact recess in a surface of the carrier element; placing the glass element on a portion of the contact element projecting above the surface; local heating of the contact element in order to connect the glass element to the carrier element via the contact element; and coating at least a part of the contact recess with a separating layer prior to the step of insertion.

2. The method according to claim 1, comprising a step of molding the contact recess prior to the step of insertion.

3. The method according to claim 1, wherein the separating layer is designed from silicon (Si) or germanium (Ge) or a refractory metal or an oxide of said substances or a refractory metal silicide.

4. The method according to claim 1, comprising a step of heating the contact element to connect the contact element to the carrier element, wherein the step of heating is performed after the step of insertion.

5. The method according to claim 4, wherein in the step of heating the portion of the contact element protruding above the surface is widened as a collar and/or formed as a rounded cap protruding in the direction of the glass plate normal.

6. The method according to claim 1, comprising a step of reducing a thickness of the portion prior to the step of placing, for leveling a surface of the portion.

7. The method according to claim 1, wherein in the step of insertion, the contact element is inserted using a reactive welding process.

8. The method according to claim 1, wherein in the step of locally heating the contact element is heated using a laser beam.

9. The method according to claim 1, wherein in the step of insertion the contact element is shaped cylindrical or spherical or partially spherical or ellipsoidal or toroidal.

10. The method according to claim 1, wherein in the step of local heating, the glass element and the support element are joined to produce an optical device.

11. The method according to claim 1, comprising a step of providing the carrier element in the form of a ceramic element and/or the glass element in the form of an ultra low expansion glass and/or the contact element in the form of a borosilicate cat glass element.

12. The method according to claim 1, wherein in the step of insertion, a plurality of contact elements are inserted into a plurality of contact recesses in the surface of the carrier element, wherein the plurality of contact recesses are arranged on a line.

13. The method according to claim 1, wherein in the step of local heating, a pressing force is exerted on the glass element to press the glass element against the contact element.

14. An optical device having a carrier element consisting of silicon carbide (SiC) or diamond or a mixture of silicon and silicon carbide (Si/SiC) and having a contact recess, particularly a reaction-bonded, silicon infiltrated silicon carbide material, or of boron carbide (B.sub.4C) or of silicon infiltrated boron carbide (Si/B.sub.4C) or of AlN and a glass element, wherein the carrier element and the glass element are firmly connected to one another using a contact element formed from a glass and inserted into the contact recess, wherein the contact recess is coated with a separating layer.

15. The optical device according to claim 14, comprising an optical sensor apparatus for detecting lengths and/or geometric positions.

Description

[0023] Exemplary embodiments of the approach presented here are shown in the drawings and explained in more detail in the following description. Shown are:

[0024] FIG. 1 shows an exemplary embodiment of a method of integrally bonding a glass element to a carrier element;

[0025] FIG. 2 shows an exemplary embodiment of a method of integrally bonding a glass element to a carrier element;

[0026] FIG. 3 shows a schematic diagram of an exemplary embodiment of a carrier element with an inserted contact element;

[0027] FIG. 4 shows a schematic diagram of an exemplary embodiment of a carrier element with an inserted contact element;

[0028] FIG. 5 shows a schematic diagram of an exemplary embodiment of a carrier element with an inserted contact element;

[0029] FIG. 6 shows a schematic diagram of an exemplary embodiment of a carrier element with an attached glass element;

[0030] FIG. 7 shows a schematic diagram of an exemplary embodiment of a carrier element with an attached glass element;

[0031] FIG. 8 shows a schematic diagram of an exemplary embodiment of an optical device; and

[0032] FIG. 9 shows a schematic top view of an exemplary embodiment of a carrier element with an arrangement of a plurality of contact recesses.

[0033] In the following description of advantageous exemplary embodiments of the present invention, the same or similar reference characters are used for the elements that are shown in various figures and having a similar effect, wherein a repeated description of these elements is dispensed with.

[0034] FIG. 1 shows a flowchart of an exemplary embodiment of a method 100 of integrally bonding a glass element to a carrier element. By way of example only, the carrier element is a ceramic carrier made of silicon-filtered silicon carbide (Si/SiC) and the glass element is a glass plate made of so-called ultra-low expansion glass. The Si/SiC can have a coefficient of thermal expansion of only 4 ppm/K between room temperature and 1000? C., for example. The method 100 comprises a step 105 of inserting at least one contact element into a contact recess in a surface of the carrier element. In this exemplary embodiment, the contact element is only inserted using a reactive welding process. In a modification of the exemplary embodiment, an oven process can be used. Furthermore, the method 100 comprises a step 110 of placing the glass element on a portion of the contact element projecting above the surface of the carrier element, wherein only exemplarily the glass plate is aligned parallel to the surface of the carrier element and brought into mechanical contact with the contact element. This results in an air gap between the surface of the carrier element and the glass element. In the following step 115 of local heating, the contact element is heated in order to connect the glass element to the carrier element via the contact element. In this exemplary embodiment, the mechanical connection of the glass element and the contact element is only realized by means of spot welding by means of a laser beam, which indirectly creates a connection between the glass element and the carrier element. The laser beam used here is only set to short pulses for a duration of 10 nanoseconds, for example, in order to heat the contact element and the glass element locally. The use of short pulses makes it possible to heat only very locally and not, as in regular welding or soldering or adhesive tempering, to heat the entire component. In this exemplary embodiment, the glass element and the carrier element are connected in the local heating step in order to produce an optical device.

[0035] FIG. 2 shows a flowchart of an exemplary embodiment of a method 100 of integrally bonding a glass element to a carrier element. The method 100 illustrated herein is the same or similar to the method described in the preceding figure, except that method 100 illustrated herein comprises additional optional steps.

[0036] In one exemplary embodiment, the method 100 has a step 200 of providing the carrier element in the form of a ceramic element and the glass element in the form of an ultra low expansion glass and the contact element in the form of a borosilicate cat glass element. The contact element is made of borosilicate glass and the carrier element is made of Si/SiC ceramic. In this exemplary embodiment, the borosilicate glass has a different coefficient of thermal expansion between welding temperature and room temperature than the Si/SiC carrier element. For example, the coefficient of thermal expansion of the borosilicate glass is 3.25 ppm/K between room temperature and 300? C. and that of the Si/SiC is 4.0 ppm/K. In this exemplary embodiment, the contact element has relatively small dimensions so that the thermal expansion difference does not lead to the contact element tearing off the carrier element during cooling.

[0037] In one exemplary embodiment, the step 200 of providing is followed by a step 205 of forming the contact recess. The contact recess is only inserted into the carrier element by means of a bore, for example, and is matched to the dimensions of the contact element.

[0038] In one exemplary embodiment, the contact recess is subsequently coated with a separating layer in step 210 of the coating process. In this exemplary embodiment, the separating layer, which can also be referred to as a barrier layer, is designed with silicon in order to chemically separate the carrier element from the contact element. In another exemplary embodiment, the separating layer may, for example, additionally or alternatively have germanium (Ge) or a refractory metal or an oxide of said fabrics and additionally or alternatively a refractory metal silicide. In this exemplary embodiment, step 210 of coating is followed by step 105 of insertion of the contact element into the coated contact recess of the carrier element. In one exemplary embodiment, a plurality of contact recesses can also be formed in the surface of the carrier element in the forming step, into which a plurality of contact elements can be inserted in the insertion step. In this case, the plurality of contact recesses can be arranged in a line. For example, the plurality of contact recesses can be arranged in the form of a line seam along a closed curve, such as a circle, or along a rectangular shape.

[0039] In one exemplary embodiment, the step 105 of insertion is followed by a step 215 of heating the contact element in order to connect the contact element to the carrier element. For example, the contact element and optionally also the carrier element are heated to a connection temperature that enables a material-locking connection between the contact element and the carrier element. By way of example only, the heating step 215 is performed as a furnace process using a normal melting furnace. In another exemplary embodiment, heating can be performed using a vacuum furnace or by means of a laser beam. In this exemplary embodiment, a portion of the contact element protruding above the surface of the carrier element is expanded as a collar by heating, in which it is merely melted by way of example. Subsequently, the component is cooled in this exemplary embodiment in order to permanently connect the contact element to the carrier element. Since the borosilicate glass element and the Si/SiC ceramic element in this exemplary embodiment have different thermal expansion coefficients, the step 215 of heating, including cooling to only a room temperature of, for example, 20? C., can nevertheless be performed with substantially low mechanical stress by using contact elements of small dimensions. In another exemplary embodiment, mechanical stresses or unevenness can be caused by soldering. During soldering, for example, the totality of the component can be heated to the soldering temperature. When cooling to room temperature, the joining position can be fixed at the solidification temperature of the solder, so that if the expansion coefficients of the soldered parts differ, a thermally induced stress is created by the cooling, which can lead to bending of the surface. The effect is equivalent to bonding, wherein the solidification temperature of the solder can correspond to the glass transition temperature of the adhesive.

[0040] In one exemplary embodiment, in the method 100 shown here, the heating step 215 is followed by a reducing step 220. For example, only one thickness of the portion of the cooled contact element protruding above the surface of the carrier element is ground and polished, resulting in a flat surface of the contact element. This removes any remaining deformation of the surface of the contact element. In an exemplary embodiment with a plurality of contact elements, the surfaces of several existing contact elements can also be leveled into a common plane. A flatness of less than 1 ?m is only achieved as an example. The glass element is placed on this flat surface facing away from the carrier element in the following step 110.

[0041] This is followed by step 115 of local heating to connect the glass element to the carrier element via the contact element. Thereby, in this exemplary embodiment, the step 115 of localized heating is performed using a laser beam. Here, the laser beam is only guided over the surface of the contact element, for example, in order to securely connect the contact element to the glass element. At the same time, in this step 115 of local heating, a pressure force is exerted on the glass element in order to press the glass element against the contact element. The pressure force can be exerted over the entire surface, for example by placing another glass element on the glass element, or only locally in the area of the contact element(s). In this exemplary embodiment, the glass element has a lower coefficient of thermal expansion than the carrier element, although this does not lead to any mechanical stress due to the point-shaped connection between the glass element and the carrier element, which is only created by local heating.

[0042] FIG. 3 shows a schematic diagram of an exemplary embodiment of a carrier element 300 with an inserted contact element 305. By way of example only, the carrier element is an element made of Si/SiC ceramic and the contact element 305 is a cylindrical element made of borosilicate glass, which can also be referred to as a glass solder. In another exemplary embodiment, the contact element can also be spherical or partially spherical or ellipsoidal or toroidal in shape. In this exemplary embodiment, the cylindrical contact element 305 is adapted to the shape of the contact recess 310 in which the contact element 305 is inserted. In this exemplary embodiment, the contact recess 310 is coated with a separating layer 315 in order to chemically separate the contact element 305 from the carrier element 300. In this exemplary embodiment, the carrier element 300 also comprises a further contact recess 320 which is coated with a further separating layer 325 and in which a further contact element 330 is inserted. The further contact element 330 is designed to be equivalent to the contact element 305.

[0043] FIG. 4A and FIG. 4B show a schematic diagram of an exemplary embodiment of a carrier element 300 with an inserted contact element 305. The carrier element 300 and the contact element 305 shown here correspond to or are similar to the carrier element and contact element described in the preceding FIG. 3. Different possible shapes of the contact element are illustrated in FIGS. 4A and 4B. In both FIGS. 4A and 4B, the carrier element 300 also comprises in this exemplary embodiment, in addition to the contact element 305 arranged in the contact recess 310, a further contact element 330 arranged in a further contact recess 320. The contact element 305 as well as the further contact element 330 are shown in the figure shown here after a step of heating. In FIG. 4A, due to the heating in this exemplary embodiment, a portion 405 of the contact element 305 projecting above the surface 400 of the carrier element 300 is widened as a collar and connected to the surface 400 by a material bond. Accordingly, a further portion 410 of the further contact element 330 is also widened and connected to the surface 400 by a material bond. In FIG. 4B, on the other hand, both the portion 405 of the contact element 305 and the further portion 410 of the further contact element 330 are shaped as a rounded cap. In other words, in the exemplary embodiment shown here, the two dowels are fused and firmly connected to the carrier element 300.

[0044] FIG. 5 shows a schematic diagram of an exemplary embodiment of a carrier element 300 with an inserted contact element 305. The carrier element 300 and the contact element 305 shown here correspond to or are similar to the carrier element and contact element described in the preceding FIGS. 3 and 4, wherein the carrier element 305 also has a further contact element 330 in addition to the contact element 305 in this exemplary embodiment. In the representation shown here, the contact element 305 and the further contact element 330 are shown after a step of reducing as described in the previous FIG. 2. Accordingly, the portion 405 of the contact element 305 as well as the further portion 410 of the further contact element 330 is flattened in order to optimize the receptacle of the glass element.

[0045] FIG. 6 shows a schematic diagram of an exemplary embodiment of a carrier element 300 with an attached glass element 600. The carrier element 300 shown here corresponds to or is similar to the carrier element described in the preceding FIGS. 3, 4 and 5. Contact elements 305, 330 are arranged in the carrier element 300, which were melted in a previous step of heating and leveled in a step of reducing. In the representation shown here, a glass element 600 is placed on the portions 405, 410 of the contact elements 305, 330 projecting above the surface 400 of the carrier element 300. The glass element 600, which may also be referred to as a glass chip or glass plate, is merely an example of a so-called ultra low expansion glass, which has a coefficient of expansion that differs from the coefficient of expansion of the carrier element 300. The glass element is aligned parallel to the surface 400 of the carrier element 300. The thickness of the portions 405, 410 results in an air gap 605 between the carrier element 300 and the glass element 600.

[0046] FIG. 7 shows a schematic diagram of an exemplary embodiment of a carrier element 300 with an attached glass element 600. The carrier element 300 and the glass element 600 shown here correspond to or are similar to the carrier element and glass element described in the preceding FIG. 6. Here, the carrier element 300, the contact elements 305, 330 and the glass element 600 are represented during a step of local heating. The portions 405, 410 act as a joining surface for attaching the glass element 600. A laser beam 700 is directed through the glass element 600 onto the other contact element 330 in order to heat it locally. Accordingly, the contact element 305 is heated with another laser beam or subsequently by means of the realigned laser beam 700. By heating the contact elements 305, 330 connected to the carrier element 300, the glass element 600 can be indirectly connected to the carrier element 300, wherein the air gap 605 remains between the carrier element 300 and the glass element 600. During local heating, the glass element 600 is pressed onto the contact elements 305, 330 in accordance with an exemplary embodiment.

[0047] FIG. 8 shows a schematic top view of an exemplary embodiment of optical device 800. In this exemplary embodiment, the optical device 800 comprises a carrier element 300 that is the same or similar to the carrier element described in the preceding FIGS. 3, 4, 5, 6 and 7. The carrier element 300 of the device 800 is materially connected to a glass element 600 by means of a method as described in the preceding FIGS. 1 and 2. In this exemplary embodiment, a sensor apparatus 805 is arranged on the glass element 600, which is merely an example of position markers for determining a geometric position. By way of example only, the optical device 800 is an xy encoder.

[0048] FIG. 9 shows a schematic top view of an exemplary embodiment of a carrier element 300 with an arrangement 900 of a plurality of contact recesses 310. The carrier element 300 shown here corresponds to or is similar to the carrier element described in the preceding FIGS. 3, 4, 5, 6, 7 and 8 and has a plurality of contact recesses, all of which are similar to the contact recess described in the preceding FIGS. 3, 4 and 6. In this exemplary embodiment, the arrangement 900 comprises more than twenty, exemplary 26 contact recesses 310 and is only exemplary rectangular in shape. In another exemplary embodiment, for example, twenty or more contact recesses 310 may be arranged along a plurality of rings. For example, an inner ring can have a diameter of 20 mm, a middle ring a diameter of 40 mm and an outer ring a diameter of 60 mm.