Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J47/00—Tubes for determining the presence, intensity, density or energy of radiation or particles
  • H01J47/001—Details
  • H01J47/002—Vessels or containers
  • H01J47/004—Windows permeable to X-rays, gamma-rays, or particles
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
  • G01T7/00—Details of radiation-measuring instruments
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B38/00—Ancillary operations in connection with laminating processes
  • B32B38/10—Removing layers, or parts of layers, mechanically or chemically
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J35/00—X-ray tubes
  • H01J35/02—Details
  • H01J35/16—Vessels; Containers; Shields associated therewith
  • H01J35/18—Windows
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J5/00—Details relating to vessels or to leading-in conductors common to two or more basic types of discharge tubes or lamps
  • H01J5/02—Vessels; Containers; Shields associated therewith; Vacuum locks
  • H01J5/18—Windows permeable to X-rays, gamma-rays, or particles
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/02104—Forming layers
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F30/00—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors
  • H10F30/301—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices being sensitive to very short wavelength, e.g. being sensitive to X-rays, gamma-rays or corpuscular radiation

Definitions

• Radiation measurement devices operate by determining a reaction of a detector device to incoming radiation.
• an x-ray camera may receive x-rays and determine their intensity as a function of location on a two-dimensional charge- coupled device, CCD, array.
• a spectrometer may be configured to determine spectral characteristics of incoming radiation, for example to determine an astrophysical redshift or to identify characteristic emission peaks of elements to analyse elemental composition of a sample.
• Soft x-rays by which it may be meant, for example, x-rays with energy below about 1 keV, providing the radiation to a detector presents with challenges.
• a suitable window may be arranged to admit soft x-rays into the vacuum where a detector may be arranged to analyse the radiation.
• a window would ideally be transparent to the soft x-rays and durable of construction, and impermeable to air to protect a detector unit.
• Transparency may be increased by reducing the thickness of the window.
• beryllium windows have been used, wherein the thinner the window is, the larger a fraction of incoming radiation is admitted through the window.
• the thinner the window is, the likelier it is to break in real-life circumstances.
• the window may be supported with a mechanical grid or it may be sandwiched between supporting structures.
• Supporting structures may take the form of web-like support structures, which partially cover and partially expose the window material. In parts where the window material is exposed by supporting structures, the window is maximally transparent to incoming radiation.
• the window layer is deposited on a non-attached side of one of the silicon wafers
• the window layer is deposited on a non-attached side of the second silicon wafer ⁇ the structure is formed of silicon of the second silicon wafer
• the method further comprises removing the mask, at least partly
• the method further comprises depositing at least one surface layer on a side of the window layer that does not face the structure
• the at least one surface layer comprises an aluminium layer
• the at least one surface layer comprises a graphene layer
• an etch stop layer is provided between the window layer and the second silicon wafer • the etch stop layer is removed at least in part
• a third silicon wafer is provided, attached to the window layer, wherein a second mask is provided on the third silicon wafer, and wherein the third silicon wafer is etched in accordance with the second mask to produce a second structure on the window layer.
• a radiation window structure comprising a continuous window layer on a supporting structure, the supporting structure on a first but not a second side of the window layer, and wherein the window layer is continuously exposed on the second side and wherein the window layer is partially exposed the first side.
• Vario us embodiments of the second aspect may comprise at least one feature from the following bulleted list:
• the window layer is provided with at least one surface layer on the second side
• the at least one surface layer comprises an aluminium layer
• the at least one surface layer comprises a graphene layer
• the window layer is comprised of at least one material from the following list: silicon nitride, A12O3, A1N, SiO2, SiC, TiO2, TiN, metallo-carbo-nitrides, graphene, pyrolytic carbon and polymer
• a method comprising obtaining a first silicon wafer comprising a silicon oxide layer thereon, the silicon oxide layer comprising a cavity, attaching a second silicon wafer on the first silicon wafer, the second silicon wafer having a window layer deposited thereon, the window layer thereby being inserted into the cavity, and etching through the first silicon wafer to expose the window layer, and etching through the second silicon wafer in accordance with a mask, to construct a support structure for the window layer.
• Various embodiments of the third aspect may comprise at least one feature from the following bulleted list: ⁇ the second silicon wafer partly exposes the window layer
• method further comprises depositing a surface layer on a side of the window layer • the surface layer is deposited on a side of the window layer that does not face the support structure
• the surface layer comprises an aluminium layer
• the surface layer comprises a graphene layer.
• Various embodiments of the fourth aspect may comprise at least one feature from the following buUeted list:
• the window layer is comprised of at least one material from the following list: silicon nitride, A1203, A1N, Si02, Ti02, TiN, metallo-carbo-nitrides, graphene, pyrolytic carbon and polymer
• the method further comprises depositing on the second side of the silicon wafer a layer, and patterning the layer into a mask that defines the shape of the supporting structure
• the layer comprises a silicon nitride layer
• FIGURE 1 illustrates an example system capable of being operated with at least some embodiments of the present invention
• FIG. 2A - FIG. 2E illustrate an example manufacturing process in accordance with at least some embodiments of the present invention
• FIG. 3 A - FIG. 3E illustrate a variant of the process of FIGs 2A - 2E.
• FIG. 4A - FIG. 4E illustrate an example manufacturing process in accordance with at least some embodiments of the present invention.
• FIG. 5A - FIG. 5E illustrate an example manufacturing process in accordance with at least some embodiments of the present invention
• FIGURE 6 is a flow graph of a method in accordance with at least some embodiments of the present invention
• FIGURE 7 is a flow graph of a method in accordance with at least some embodiments of the present invention.
• FIGURE 1 illustrates an example system capable of being operated with at least some embodiments of the present invention.
• the illustrated system relates to x-ray fluorescence, to which the present invention is not limited, rather, windows built in accordance with the present invention may find application also more broadly.
• FIGURE 1 irradiates sample 130 with primary x- rays 102 from primary x-ray source 140, stimulating matter comprised in sample 130 to emit, via fluorescence, secondary x-ray radiation 103, spectral characteristics of which are determined, at least partly, in x-ray detector 120.
• X-ray detector 120 comprises a window region 115, which is arranged to admit x-rays into X-ray detector 120.
• Window region 115 is illustrated in an enlarged view 115E at the bottom of FIGURE 1, wherein a gap in the outer housing of analytic device 110 is shown.
• a window layer 117 is disposed, preventing inflow of air from outside analytic device 110 to inside analytic device 110 while allowing x-rays, such as, for example, soft x-rays, to enter analytic device 110, so that these x-rays may be analysed in x-ray detector 120.
• Window layer 117 may be comprised of silicon nitride, for example.
• window layer 117 may be comprised of include A1203, A1N, Si02, SiC, Ti02, silicon nitride, TiN, metallo- carbo-nitrides such as TiAlCN, graphene, pyrolytic carbon and polymers, such as polyimide.
• window region 115 may be disposed in the housing of analytic device 110, rather than at X-ray detector 120.
• Window layer 117 is supported by supporting structure 119 on one side. While illustrated on the inner side facing the inside of X-ray detector 120, supporting structure 119 may, in other embodiments, alternatively be on the outward facing side. Supporting structure 119 may, in some embodiments, be present on one side but not the other side, in other words, supporting structure 119 may be limited to one side of window layer 117. Supporting structure 119 may be comprised of silicon, for example.
• Supporting structure 119 may take a form and shape that is suitable for supporting window layer 117 thereon, to withstand atmospheric pressure, for example, in case the inside of x-ray detector 120 is maintained at tow pressure, or, indeed, vacuum or near-vacuum.
• supporting structure 119 may comprise a square or rectangular layout, or a spider-web shape, to provide support for window layer 117 while not obscuring too much of window layer 117.
• supporting structure 119, attached to window layer 117 will partially obscure and partially expose window layer 117.
• window layer 117 may be completely exposed on a first side and partly exposed on a second side, the supporting structure being on the second side.
• completely exposed, or continuously exposed it is meant window layer 117 is exposed in a manner that an area of window layer 117 in active use is not obstructed by a support structure on the continuously exposed side.
• Window layer 117 may be continuous in nature, by which it is meant the layer is not interrupted, for example, in accordance with the support structure.
• a continuous layer may be planar in the sense that it lies in a single plane.
• Window layer 117 may be thin, in the nanometer range, while extending over an opening which is in the order of a few millimetres, or centimetres, in size.
• Window layer 117 may have, for example on a side not facing support structure 119, at least one supplementary layer.
• supplementary layers include a thin aluminium layer and a graphene layer.
• An aluminium layer may block, at least partly, visible light from entering through window layer 117.
• Graphene on the other hand, may enhance an ability of window layer 117, for example when made of silicon nitride, to prevent gas molecules, such as air, from penetrating through window layer 117.
• supplementary layers may be applied easier and the resulting layers have fewer defects. This provides the beneficial technical effect that the layers function better in their respective purposes.
• Supplementary layers may alternatively be referred to as surface layers.
• FIG. 2E illustrate an example manufacturing process in accordance with at least some embodiments of the present invention.
• the process begins at the situation of FIG. 2A, where a silicon wafer 210 is obtained, comprising at least a first silicon oxide layer 214, and, optionally, a second silicon oxide layer 212.
• first silicon oxide layer 214 has been patterned, by removing part thereof, to leave behind a mask that defines a shape of a supporting structure. The pattern need not penetrate all the way through first silicon oxide layer 214.
• the silicon wafer is also patterned before oxidation, to generate deeper structures.
• a second silicon wafer 220 has been attached on top of the mask layer 214.
• Second silicon wafer 220 has deposited thereon a window layer 222, which may comprise silicon nitride, for example.
• An optional silicon nitride layer 216 may be deposited on the opposite side of first silicon wafer 210. Where present, second silicon oxide layer 212 may be removed to arrive at the situation illustrated in FIG. 2C.
• second silicon wafer 220 may be provided with an oxide layer, which is patterned to form the mask. Then first silicon wafer 210 may be attached onto second silicon wafer 220 to cover the mask. Subsequently, first silicon wafer 210 may be etched, as described below.
• An advantage of providing the mask on second silicon wafer 220 is that attaching errors will have no effect on etching.
• first silicon wafer 210 has been etched to expose mask 214 and, partially, second silicon wafer 220, masked by mask 214.
• etching is continued to partially expose window layer 222 from the side of first silicon wafer 210.
• a supporting structure is constructed of second silicon wafer 220, which supports window layer 222.
• the exposed silicon oxide from mask 214 may be removed.
• the first silicon wafer 210 is provided with mask 214, the second silicon wafer 220 is attached to the first silicon wafer 210 on the first side, leaving mask 214 between these wafers, and then the first silicon wafer 210 and the second silicon wafer 220 are etched from the second side, different from the first side, to partially expose window layer 222.
• the supporting structure is thereby formed of second silicon wafer 220, on the second side of window layer 222.
• a sacrificial etch stop layer for example 1 micrometer of PECVD Si02 or a multilayer structure, may be provided between second silicon wafer 220 and window layer 222, to protect window layer 222, which may be delicate, during chemical and/or mechanical stress during silicon etching phases of the process.
• FIG. 3B corresponds to the situation of FIG. 2B, with the exception that first silicon wafer 210 is partly etched, using mask 214, to facilitate the subsequent etching from the other side.
• the resulting cavities are denoted in FIG. 3B with reference sign 310.
• a second silicon wafer 220 has been attached on top of the mask layer 214.
• Second silicon wafer 220 has deposited thereon a window layer 222, which may comprise silicon nitride, for example.
• An optional silicon nitride layer 216 may be deposited on the opposite side of first silicon wafer 210.
• second silicon oxide layer 212 may be removed to arrive at the situation illustrated in FIG. 2C.
• a quantity of silicon from first silicon wafer 210 remains, covering parts of mask 214. This is due to the cavities 310 created earlier. The remaining silicon is denoted in FIG. 3D with reference sign 320. This silicon may be removed in subsequent phases of the process.
• the first silicon wafer 210 is etched from a first side
• the second silicon wafer 220 is attached to the first silicon wafer 210 on the first side, leaving mask 214 between these wafers, and then the first silicon wafer 210 and the second silicon wafer 220 are etched from the second side, different from the first side, to partially expose window layer 222.
• the supporting structure is thereby formed of second silicon wafer 220, on the second side of window layer 222.
• a second supporting structure may be constructed on the other side of window layer 222. While the second supporting structure may make deposition of a further layer on window layer 222 more difficult, having a supporting structure on both sides of window layer 222 results in superior rigidity for the resulting window structure.
• Such a structure may be constructed as described above in connection with FIGs 2A - 2E or FIGs 3A - 3E, wherein further a third silicon wafer is attached to the other side of window layer 222, the third silicon wafer provided with a silicon oxide layer on top which is patterned to produce a second mask, and subsequently etching to produce the second supporting structure using the second mask and to partially expose window layer 222 also from the top side.
• the other supporting structure may be produced as described above in connection with FIGs 2A - 2E or FIGs 3A - 3E.
• second silicon wafer 420 has been attached to first silicon wafer 410.
• This attaching may be based on oxide only, for example.
• window layer 422 is inserted in the cavity of first silicon oxide layer 414.
• a gap may be left between window layer 422 and the bottom of the cavity.
• a top silicon oxide layer 424 is obtained on top of second silicon wafer 420.
• FIG. 5A - FIG. 5E illustrate an example manufacturing process in accordance with at least some embodiments of the present invention.
• a silicon wafer 510 has been obtained, with a buried silicon oxide layer 516, as well as silicon oxide layers 512 and 514, as illustrated. This may be obtained, for example, by attaching two wafers to each other, such that a silicon oxide layer on one of these wafers is left therein between. Further, silicon wafer 510 has been etched from the bottom side, using buried silicon oxide layer 516 as an etch stop.
• window/mask layers for example silicon nitride, are deposited on both sides. Such layers are illustrated as layers 520 and 522.
• the top mask layer 520 is patterned in the shape of a supporting structure, such as, for example, a supporting grid or web structure.
• a supporting structure such as, for example, a supporting grid or web structure.
• window layer 522 is continuously exposed from the bottom side, a supplementary layer or layers may be deposited thereon, as described above.
• FIGURE 6 is a flow graph of a method in accordance with at least some embodiments of the present invention.
• Phase 610 comprises obtaining a first silicon wafer comprising a mask on a first side.
• Phase 620 comprises attaching a second silicon wafer on the first side of the first silicon wafer.
• phase 630 comprises etching from a second side of the first silicon wafer to partially expose a silicon nitride layer deposited on the second silicon wafer and to leave a structure defined by the mask supporting the silicon nitride layer.
• the silicon nitride layer is deposited on a non attached side of the second silicon wafer, that is, a side not facing the first silicon wafer.
• FIGURE 7 is a flow graph of a method in accordance with at least some embodiments of the present invention.
• Phase 710 comprises obtaining a first silicon wafer comprising a silicon oxide layer thereon, the silicon oxide layer comprising a cavity.
• Phase 720 comprises attaching a second silicon wafer on the first silicon wafer, the second silicon wafer having a silicon nitride layer deposited thereon, the silicon nitride layer thereby being inserted into the cavity.
• phase 730 comprises etching through the first silicon wafer to expose the silicon nitride layer, and etching through the second silicon wafer in accordance with a mask, to construct a support structure for the silicon nitride layer.

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• 2017
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