VACUUM-TIGHT ELECTRICAL FEEDTHROUGH

Abstract

Vacuum-tight electrical feedthrough 10, comprising an electrically insulating insulator element 2 having a through-opening 23, having a first boundary surface 21 adjacent to the through-opening, and having a second boundary surface 22 also adjacent to the through-opening and opposite to the first boundary surface, and an electrically conductive conductor element 1 which extends through the through-opening 23 and which is connected to the insulator element 2 in a vacuum-tight manner along a circumferential line of the conductor element 1,

wherein the insulator element 2 is transmissive to electromagnetic radiation 25 in an optical wavelength range, and

wherein the first boundary surface 21 and/or the second 22 boundary surface is formed as a curved surface, in particular as a convex or concave surface.

The invention further relates to a vacuum pressure sensor having the vacuum-tight electrical feedthrough and a method for measuring a radiation intensity of electromagnetic radiation.

Claims

1. Vacuum-tight electrical feedthrough (10), comprising an electrically insulating insulator element (2) having a through-opening (23), having a first boundary surface (21) adjacent to the through-opening, and having a second boundary surface (22) also adjacent to the through-opening and opposite to the first boundary surface, and an electrically conductive conductor element (1) which extends through the through-opening (23) and which is connected in a vacuum-tight manner to the insulator element (2) along a circumferential line of the conductor element (1), wherein the insulator element (2) is transmissive to electromagnetic radiation (25′, 25″, hν) in an optical wavelength range, and wherein the first (21) and/or the second (22) boundary surface is formed as a curved surface, in particular as a convex or concave surface.

2. Electrical feedthrough (10) according to claim 1, further comprising a metallic frame (4) which is connected in a vacuum-tight manner to the insulator element (2) along a circumferential line of the insulator element separating the first and second boundary surfaces.

3. Electrical feedthrough (10) according to one of claim 1 or 2, wherein the conductor element (1) extends along an axis, and wherein the first boundary surface (21) has a first region and the second boundary surface (22) has a second region, wherein the first and second regions are in the form of first and second surfaces of revolution with the axis as a common axis of revolution.

4. Electrical feedthrough (10) according to one of claims 1 to 3, wherein the conductor element (1) is of rod-shaped design having a first rod end (11) projecting further beyond the first boundary surface (21) than a second rod end (12) projects beyond the second boundary surface (22).

5. Electrical feedthrough (19) according to claim 4, wherein the insulator element (2) forms an imaging lens which images at least a first object point in the region between the first boundary surface (21) and the first rod end (11) onto a first image point that is further from the first boundary surface than the second rod end (12).

6. Electrical feedthrough (10) according to claim 5, wherein the insulator element (2) is a plano-convex lens having a central through-opening (23).

7. Electrical feedthrough (10) according to one of claims 1 to 6, wherein the insulator element (2) is made of sapphire.

8. Electrical feedthrough (10) according to one of claims 1 to 7, wherein a fused glass ring (3) forms a vacuum-tight connection between conductor element (1) and insulator element (2).

9. Vacuum pressure sensor (30) having an electrical feedthrough (10) according to one of claims 1 to 8.

10. Vacuum pressure sensor (30) according to claim 9, wherein the vacuum pressure sensor is formed as a cold cathode vacuum meter and wherein the conductor element (1) forms the anode of the cold cathode vacuum meter.

11. Vacuum pressure sensor (30) according to claim 10, wherein the first boundary surface (21) faces a plasma region of the vacuum pressure sensor, and wherein an optical sensor (7) is arranged on the side of the second boundary surface (22) such that electromagnetic radiation (25) of the mentioned optical wavelength range can propagate from the plasma region through the insulator element (2) to the optical sensor (7).

12. Vacuum pressure sensor (30) according to claim 11, comprising an electrical feedthrough (10) according to claim 5, wherein the first object point is located in the plasma region (26) of the vacuum pressure sensor, and wherein the optical sensor (7) is arranged at the first image point.

13. Vacuum pressure sensor (30) according to claim 11 or 12, wherein the plasma region is restricted by a magnet assembly (6) to an end of the anode remote from the insulator element (2).

14. Vacuum pressure sensor (30) according to one of claims 9 to 13, wherein the conductor element (1) has an electrically insulating coating in a region near the insulator element (2).

15. Method for measuring a radiation intensity of electromagnetic radiation in an optical wavelength range, wherein the method comprises the steps of: a) providing a vacuum apparatus having an electrical feedthrough (10) according to one of claims 1 to 8; b) supplying electrical energy through the conductor element (1) into a vacuum region of the vacuum apparatus to ignite and maintain a plasma in the vacuum region; c) measuring the radiation intensity of electromagnetic radiation emitted from the plasma by means of an optical sensor (7); wherein the electromagnetic radiation radiates from the plasma through the insulator element (2) onto the optical sensor (7).

Description

[0048] Exemplary embodiments of the present invention are explained in further detail below with reference to figures, wherein:

[0049] FIG. 1 schematically shows in a simplified manner a cross-section through a vacuum-tight electrical feedthrough according to the invention;

[0050] FIG. 2 shows in the subfigures FIG. 2.a) to 2.d) cross-sections through embodiments of the electrical feedthrough;

[0051] FIG. 3 shows a cross-section through an embodiment of the vacuum pressure sensor;

[0052] FIG. 4 shows in subfigure 4.a) a cross-section through an embodiment of the vacuum pressure sensor together with a bundle of beams of electromagnetic radiation and their impingement on an image plane; in FIG. 4.b) in a top view of the image plane the distribution of radiation impinging on the image plane.

[0053] FIG. 1 shows a cross-section through a vacuum-tight electrical feedthrough 10 according to the invention. An electrically conductive conductor element 1 passes through a through-opening 23 of an insulator element 2. The conductor element shown has the shape of a rod having a first rod end 11 and a second rod end 12. There is a vacuum-tight connection between conductor element 1 and insulator element 2, which is symbolized in cross-section by filled circles. The vacuum-tight connection extends along a circumferential line around the conductor element and is intersected at two points in the plane of this cross-sectional view. On two opposite sides of the insulator element, a first boundary surface 21 of the insulator element and a second boundary surface 22 of the insulator element are adjacent to the through-opening. Exemplary electromagnetic radiation paths 25′, 25″ are shown with dashed line arrows. The exemplary radiation paths 25′, 25″ pass through the insulator element, which is transmissive in an optical wavelength range, and change direction at the first 21 and second 22 boundary surfaces. The two radiation paths shown strike the insulator element parallel to each other and parallel to the direction of the feedthrough axis, i.e., parallel to the longitudinal extension of the conductor element. After passing through the insulator element, the two radiation paths converge, illustrating the focusing effect of the electrical feedthrough according to the invention. In the embodiment shown, the first boundary surface is a curved surface, with an outer region being concave in shape and a central region being convex in shape. The second boundary surface is flat in the case shown.

[0054] FIGS. 2.a) to 2.d) show variants of possible combinations of curvature types of the first and second boundary surfaces in cross-section. FIG. 2.a) shows a plano-convex arrangement, FIG. 2.b) shows a bi-convex arrangement, FIG. 2.c) shows a concave-convex arrangement and FIG. 2.d) shows an arrangement with a completely planar first boundary surface and a second boundary surface which is planar in the region around conductor elements 1, 1′ which have been passed through, wherein a central region between the conductor elements is of convex design. Variant 2.d) illustrates an embodiment with more than one conductor element. The cross-section extends through the conductor element 1 and also through another conductor element 1′ having the same characteristics as the conductor element 1 already discussed. FIGS. 2.a) to 2.c) show feedthroughs in which the conductor element passes centrally through the insulator element. These cross-sections may be, for example, the cross-sections of an electrical feedthrough of rotationally symmetrical construction. Although not illustrated with a graphic element, the feedthroughs shown in FIG. 2 and the following figures are designed to be vacuum-tight.

[0055] FIG. 3 shows a cross-section of a vacuum pressure sensor according to the invention. This is a vacuum pressure sensor which is designed as a cold cathode vacuum meter. The conductor element 1 forms the anode of the cold cathode vacuum meter. Conductor element 1 and insulator element 2 form an electrical feedthrough according to the invention, by means of which electrical energy can be supplied from a voltage source 5 to a plasma region 26, the position of which is indicated by the dashed line, within the pressure sensor. A magnet assembly 6 ensures that moving charged particles (electrons, ions) in the plasma region move along a curved path. Electromagnetic radiation (hv), which is characteristic of the state of the plasma, passes through the insulator element 2, which is transmissive at least in one optical wavelength range, to an optical sensor 7. Due to the curved boundary surfaces of the insulator element, the radiation is bundled and arrives at the optical sensor 7 with increased intensity. The optical sensor 7 can be a simple radiation sensor, e.g. a light sensor, but it can also be a more complex optical sensor, e.g. a spectrometer. In the arrangement shown, the outer wall of the vacuum pressure sensor forms the cathode of the cold cathode vacuum meter. It is also electrically connected to the voltage source 5. The side of the vacuum pressure sensor leading to the vacuum system is labeled “Vacuum System” without any details of the vacuum system being illustrated. It is understood that this side of the vacuum pressure sensor is connected to the vacuum system in a vacuum-tight manner. In the embodiment shown, the electrical feedthrough comprises a metallic frame 4. By means of one fused glass ring 3 each, the conductor element 1 is connected to the insulator element 2 in a vacuum-tight manner and the insulator element 2 is connected to the metallic ring 4 in a vacuum-tight manner. The metallic ring 4 is welded to the cathode, which is cylindrical in the embodiment shown and is also made of a metal.

[0056] For example, the insulator element of the electrical feedthrough can be designed as a plano-convex lens as shown here, wherein the first boundary surface has a spherical curvature with a radius of curvature R in sections. An arrangement with a spectrometer, which is arranged for example at a distance d=10 mm from the planar second boundary surface on the side facing away from the vacuum, will be combined for example with a radius of curvature R=8.5 mm of the first boundary surface in order to obtain a high radiation intensity at the optical sensor 7 if the refractive index of the insulator element corresponds to the refractive index of sapphire, in particular if the insulator element is made of sapphire. An insulator element that is flat on one side has the advantage that the orientation of the insulator element can be controlled very precisely during the manufacturing process of the electrical feedthrough. This has the advantage that the position of a focal point can be precisely controlled by simple means, resulting in high reproducibility of the position of the focal point.

[0057] Two beam paths of electromagnetic radiation 25′, 25″, which emanate from the plasma region 26 and are focused by the insulator element 2, which is transmissive to the radiation, towards the optical sensor 7, are shown. The wavelength electromagnetic radiation hν lies in the optical wavelength range. Pole shoes 27 guide the magnetic field of the magnet assembly 6 in such a way that the plasma region 26 is restricted to a region of the anode which is remote from the insulator element 2. The anode is formed by the conductor element 1. The cathode 28 of the vacuum pressure sensor is arranged in a cylindrical shape around the central anode in the section shown. The area of the cathode shown in dashed lines can form a transition to the vacuum system in any geometry, but in a vacuum-tight manner. The direction to the vacuum system is indicated by an arrow. The vacuum system may be a vacuum system, for example a vacuum system for depositing thin films on substrates and/or for processing semiconductor wafers.

[0058] FIG. 4 shows a cross-section through a vacuum pressure sensor according to the invention with a bundle of beams of electromagnetic radiation and their impingement on an image plane 29 as can be seen from a simulation of the beam paths. A plurality of different beams originating in an area around the anode and impinging on the insulator element are focused on the image plane. In this case, the approximately circular area on which the rays impinge on the image plane is smaller than the area on which the same plurality of rays impinge on the insulator element. This means that the radiation intensity in the circular area on the image plane is higher than the radiation intensity on that boundary surface of the insulator element which faces the vacuum side of the pressure sensor. An optical sensor, such as is present in one embodiment of the pressure sensor, can be arranged with its sensitive area where the circular area on the image plane can be seen. As can be read from the millimeter scale on the x and y axes (x [mm], y [mm]) in the image plane, the beams can be focused on a circular area approximately 0.5 mm in diameter. For the simulation shown, the geometry parameters were used as described in FIG. 3, i.e. in particular R=8.5 mm and d=10 mm, together with the refractive index of sapphire for the insulator element 2.

LIST OF REFERENCE SIGNS

[0059] 1 Conductor element [0060] 1′ Further conductor element [0061] 2 Insulator element [0062] 3 Fusion glass ring [0063] 4 Metallic frame (welding ring) [0064] 5 Voltage source [0065] 6 Magnet assembly [0066] 7 Optical sensor [0067] 10 Electrical feedthrough [0068] 11 First rod end [0069] 12 Second rod end [0070] 21 First boundary surface [0071] 22 Second boundary surface [0072] 23 Through-opening [0073] 24 Vacuum-tight connection [0074] 25′, 25″, hν Electromagnetic radiation [0075] 26 Plasma region [0076] 27 Pole shoe [0077] 28 Cathode [0078] 29 Image plane [0079] 30 Vacuum pressure sensor [0080] N, S North pole, south pole of the magnet assembly [0081] U Electrical voltage [0082] Vacuum side Side to which vacuum is applied during operation