Method for producing diamond membranes with structures for use in quantum systems and / or quantum sensors

Abstract

The present invention relates to a method for producing diamond membranes with structures for use in quantum systems and / or quantum sensors, wherein the method comprises: - providing a diamond membrane that comprises a first surface and a second surface; - creating structures in the diamond membrane by applying light from a laser to the first surface of the diamond membrane; and - dry etching the second surface of the diamond membrane to reduce a thickness of the diamond membrane.

Description

[0001] METHOD FOR PRODUCING DIAMOND MEMBRANES WITH STRUCTURES FOR USE IN QUANTUM SYSTEMS AND / OR QUANTUM SENSORS

[0002] The present invention relates to a method for producing diamond membranes with structures for use in quantum systems and / or quantum sensors, a diamond membrane obtained by such method, and a quantum system comprising such a diamond membrane.

[0003] For quantum technologies like quantum computers, quantum network end nodes and quantum sensors, diamond is a very suitable material. Diamond is the hardest material on earth. Therefore, it is very hard to machine diamond, especially into structures like (sub) micrometer-thin membranes, which are crucial for quantum technologies. Diamond has the advantageous characteristic that it can host color centers, which can be used as qubits with promising properties for quantum technologies. Many of these quantum applications require thin devices, for example in the range 0.1-10 micrometer, that can be scalable shaped into platelets of tailored sizes. These platelets may have a side length from a few micrometers to hundreds of micrometers. Diamond membranes can for example be used to incorporate color centers into optical resonators or to create integrated photonic structures like waveguides and photonic crystal cavities.

[0004] Conventionally, the shaping of these diamond devices is performed using a tedious and lengthy process of patterning structures in diamond using advanced lithography techniques and selective reactive ion etching into the diamond. These diamond devices typically have a thickness of more than 30 micrometers.

[0005] A downside of this conventional process is that it is lengthy, labor intensive and that many different machines are needed for obtaining the desired diamond device, such as a machine which can provide a high-resolution electron beam exposure for applying structures on the diamond devices, a spin coater, and a reactive ion etcher for reactive ion etching.

[0006] It is an object for the present disclosure to obviate or at least reduce the abovementioned downsides. In particular, it is an object of the present disclosure to provide an easier production method of diamond devices.

[0007] This object is achieved by a method for producing diamond membranes with structures for use in quantum systems and / or quantum sensors, comprising: providing a diamond membrane that comprises a first surface and a second surface; creating structures in the diamond membrane by applying light from a laser to the first surface of the diamond membrane; and dry etching the second surface of the diamond membrane to reduce a thickness of the diamond membrane.

[0008] An advantage of the method according to the present disclosure is that the method allows to reduce the patterning step into a single fabrication step, namely creating structures by applying light from a laser. This step can also be denoted laser cutting. A further advantage of creating structures by applying light from a laser is that this step can easily be done in-house, but can also be easily outsourced. Compared to the fabrication method according to the prior art where lithography is involved, the method of producing the diamond membranes according to the present disclosure reduces the number of machines that are needed from five machines to two machines. This saves production costs. Additionally, the equipment needed is lower in cost, which in total realizes an equipment investment cost which is approximately a factor of four lower than the production method of the prior art.

[0009] Another advantage of the method is that due to the easier process, the risk of losing or breaking the diamond membrane during handling is reduced. Additionally, or alternatively, the risk of machine downtime is minimized.

[0010] The disclosure relates to, in a first step, providing a diamond membrane. In a second step, structures are created in the diamond membrane by applying laser light from a laser. These structures are created, in, at, or on the first surface. In a third step, the second surface, that is opposite of the first surface, is dry etched. By dry etching the second surface the thickness of the diamond membrane is reduced, such that the diamond membrane acquires a suitable thickness for use in certain quantum systems and / or quantum sensors. The thickness of the diamond membrane must be understood as the thickness from the first surface towards the second surface.

[0011] The method for producing diamond membranes with structures for use in quantum systems and / or quantum sensors can also be a named a method for manufacturing diamond membranes with structures for use in quantum systems and / or quantum sensors.

[0012] In an embodiment the structures comprise 3D-structures formed by the removal of material.

[0013] The material that is removed is the material comprising the diamond membrane. In other words, diamond is removed from the diamond membrane.

[0014] In an embodiment the structures comprise an absence of material below the first surface of the diamond membrane.

[0015] The absence of material below the first surface must be understood as an absence of material in the volume between the first surface and second surface of the diamond membrane. Below is in the present context means located in the volume defined between the first and second surface. It is clear for the skilled person that the volume may be imaginary or real. In one way, the volume can be seen as an infinite volume between the first and second surface of the diamond membrane. In another way, the volume may denote the volume occupied by the diamond membrane. In that case, the volume is delimited by four side walls extending orthogonally to the first and second surface, and each side wall extending orthogonally with respect to adjacent side walls. The volume may define a rectangular cuboid. In an embodiment the method further comprises: arranging, prior to the step of creating structures in the diamond membrane, a protective layer on the first surface of the diamond membrane.

[0016] By arranging the protective layer on the first surface, the first surface is protected from damage by the laser light. In this way, the laser light can still create the desired structures on the diamond membrane, while the protective layer protects the surrounding first surface from being damaged. In this way, graphitization of the first surface can mostly be prevented.

[0017] In an embodiment the protective layer is present on the first surface during the step of creating structures in the diamond membrane.

[0018] By arranging the protective layer on the first surface during the application of laser light, the first surface is protected from damage by the laser light. In this way, the laser light can still create the desired structures on the diamond membrane, while the protective layer protects the surrounding first surface from being damaged. In this way, graphitization of the first surface can mostly be prevented.

[0019] In an embodiment, the method further comprises arranging, prior to and during the step of creating structures in the diamond membrane, a protective layer on the first surface of the diamond membrane.

[0020] In an embodiment the protective layer comprises a polymer, such as polyvinyl alcohol (PVA), and / or metal, such as chromium.

[0021] According to experiments PVA and chromium are suitable materials for the protective layer. The protective layer may be a layer of PVA. The protective layer may be a layer of chromium. The protective layer may be a layer in which PVA and chromium are mixed. The protective layer may comprise a first layer of PVA and a second layer of chromium, wherein the first layer and the second layer together form the protective layer.

[0022] In an embodiment a thickness of the protective layer is in the range of 10 nanometres - 10 micrometres, preferably in the range of 100- nanometres - 5 micrometres, and most preferably in the range of 150 nanometres - 2 micrometres.

[0023] The abovementioned thicknesses of the protective layer provide a sufficient protection of the first surface during the creation of the structures in the first surface.

[0024] In an embodiment the step of dry etching the second surface comprises reactive ion etching (RIE).

[0025] An advantage of reactive ion etching is that material on the second surface of the diamond membrane is removed in a controlled manner. The reactive ion etching may comprise inductively coupled plasma reactive ion etching (ICP RIE).

[0026] In an embodiment the reactive ion etching comprises: creating a plasma that comprises argon, chlorine and / or oxygen; and applying the charged ions of the argon, chlorine and / or oxygen to the second surface of the diamond membrane.

[0027] Experiments have shown that argon, chlorine and / or oxygen provide an effective etching of the second surface. In this way, the thickness of the diamond membrane can effectively be reduced.

[0028] In an embodiment the reactive ion etching comprises: creating a first plasma that comprises argon and / or chlorine; applying the charged ions of the argon and / or chlorine to the second surface of the diamond membrane; creating a second plasma that comprises oxygen; and applying the charged ions of the oxygen to the second surface of the diamond membrane.

[0029] The argon and / or chlorine etching is mainly used to smooth the second surface of the diamond membrane. The oxygen etching is mainly used to reach the desired thickness of the diamond membrane.

[0030] In an embodiment the method further comprises: arranging a mask, for example a mask of fused quartz, on the second surface of the diamond membrane before dry etching the second surface.

[0031] By arranging a mask on the second surface before dry etching part of the second surface is protected from etching by the ions. In this way, part of the second surface keeps its thickness, while the thickness of the part of the second surface that is not protected or covered by the mask is reduced. In this way, a first part of the diamond membrane is thicker than a second part of the diamond membrane. This can provide a sort of frame for handling. This has the advantage that the chance of breaking of the diamond membrane is reduced and / or that the ease of handing the diamond membrane is improved.

[0032] In an embodiment the method further comprises: cleaning the first surface of the diamond membrane by applying a boiling triacid solution to the first surface of the diamond membrane.

[0033] By cleaning the first surface of the diamond any graphitization which has occurred during the creation of the structures can be removed. This improves the characteristics of the diamond membrane for quantum systems and / or quantum sensors.

[0034] In an embodiment the laser is a femtosecond-pulsed laser.

[0035] The femtosecond-pulsed laser can effectively create structures, such as slits or trenches, in, at, or on the diamond membrane.

[0036] In an embodiment the first surface and the second surface of the diamond membrane are oppositely arranged. The first surface and the second surface are preferably substantially planar surfaces that are on opposite sides of the diamond membrane.

[0037] In an embodiment the step of creating structures in the diamond membrane comprises creating trenches and / or slits in the diamond membrane.

[0038] In an embodiment the thickness of the diamond membrane prior to the steps of creating structures and dry etching is in the range of 20-200 micrometres, preferably in the range of 50-100 micrometres, and most preferably in the range of 50-70 micrometres, for example 60 micrometres.

[0039] In an embodiment the thickness of the diamond membrane after the steps of creating structures and dry etching is in the range of 0.05-50 micrometres, preferably in the range of 0.1-20 micrometres, and most preferably in the range of 0.1-10 micrometres, for example 5 micrometres.

[0040] In an embodiment a depth of the structures in the diamond membrane is in the range of 1- 50 micrometres, preferably in the range of 3-20 micrometres, and most preferably in the range of 5-15 micrometres, for example 10 micrometres.

[0041] In an embodiment a spot size of the light from the laser is in the range of 0.1-5 micrometres, preferably in the range of 0.5-2 micrometres, and most preferably is in the range of 0.8- 1.5 micrometres, for example 1 micrometre.

[0042] With the abovementioned spot sizes adequate structures can be manufactured in the diamond membrane.

[0043] In an embodiment the method further comprises: dry etching the first surface of the diamond membrane after the step of creating structures in the diamond membrane.

[0044] By dry etching the first surface of the diamond membrane the first surface of the diamond membrane is smoothened. This improves the working of the structures on the diamond membrane.

[0045] In an embodiment the dry etching comprises reactive ion etching (RIE).

[0046] An advantage of reactive ion etching is that material on the first surface of the diamond membrane is removed in a controlled manner. The reactive ion etching may comprise inductively coupled plasma reactive ion etching (ICP RIE).

[0047] In an embodiment the reactive ion etching comprises: creating a plasma that comprises argon and / or chlorine; applying the charged ions of the argon and / or chlorine to the first of the diamond membrane, and optionally: creating a second plasma that comprises oxygen; and applying the charged ions of the oxygen to the second surface of the diamond membrane. The argon and / or chlorine etching is mainly used to smooth the second surface of the diamond membrane. The oxygen etching is mainly used to reach the desired thickness of the diamond membrane.

[0048] The present disclosure further relates to a diamond membrane obtained by the method according to any one of the foregoing claims.

[0049] The diamond membrane has similar effects and advantages as described for the method.

[0050] The present disclosure further relates to a quantum system comprising a diamond membrane according to the present disclosure.

[0051] The quantum system has similar effects and advantages as described for the method and the diamond membrane.

[0052] Further advantages, features and details are elucidated on the basis of preferred embodiments thereof, wherein reference is made to the accompanying drawings, wherein: figure 1, an example of a diamond membrane; figures 2A-B, different stages of a first example of a diamond membrane during production; figures 3A-C, different stages of a second example of a diamond membrane during production; figure 4, an example of a reactive ion etcher; figure 5, a first example of a method; and figure 6, a second example of a method.

[0053] Diamond membrane 2 (figure 1) comprises first surface 4 and second surface 6. First surface 4 and second surface 6 are oppositely arranged. Between first surface 4 and second surface 6 four side surfaces 8a, 8b, 8c, 8d are arranged. On first surface 4 patterns can be formed. These patterns make diamond membrane 2 suitable for quantum applications, such as quantum systems and / or quantum sensors. Optionally, a colour centre may be arranged in diamond membrane 2. The colour centre can for example be introduced by ion implantation through first surface 4 or second surface 6, after which the ion may form a colour centre. Optionally, the colour centre has to be formed by annealing diamond membrane 2. For example, diamond membrane 2 can be annealed for 6 hours at a temperature of 1100 degrees Celsius. It is clear for the skilled person that any technique of providing a colour centre in diamond membrane 2 may be used in the context of the present disclosure.

[0054] Arranged above diamond membrane 2 is femtosecond-pulsed laser 10. In the illustrated embodiment, laser 10 is an Menlo Systems Bluecut laser that produces pulses of laser light with a wavelength of 515 nanometres, has a repetition rate of 500 kHz, and a duration of 300 femtoseconds, as described in Guo, Y., Hadden, J. P., Gorrini, F., Coccia, G., Bharadwaj, V., Kavatamane, V. K., ... & Bennett, A. J. (2024). Laser-written waveguide-integrated coherent spins in diamond, arXiv preprint arXiv:2403.07850. The laser may have a numerical aperture objective of 1.25. An alternative suitable laser is an Yb:KGW system (Pharos, Light Conversion) with 230 femtosecond pulse duration, uses a 515 nanometres wavelength with a numeral aperture objective of 1.25, as described in Sotillo, B., Bharadwaj, V., Hadden, J. et al. Diamond photonics platform enabled by femtosecond laser writing. Sci Rep 6, 35566 (2016). Laser 10 is configured to creature structures on first surface 4 of diamond membrane 2. It is clear for the skilled person that any laser that has sufficient power to create patterns in first surface 4 of diamond membrane 2 is suitable for the present disclosure.

[0055] On first surface 4 (figure 2A) of diamond membrane 2 protective layer 14 is arranged. In the illustrated embodiment, protective layer 14 comprises pattern 12. In the illustrated embodiment pattern 12 is a trench. However, pattern 12 can be any suitable structure that can be used in quantum systems, such as a nanophotonic waveguide, an optical resonator or a photonic crystal cavity. In the illustrated embodiment protective layer 14 is a polyvinyl alcohol (PVA) layer. A possible way of applying protective layer 14 on first surface 4 of diamond membrane 2 is by spraying. Protective layer 14 is applied before laser 10 creates structures on first surface 4 of diamond membrane 2. In this way, damage to first surface 4 of diamond membrane 2 is reduced. It may be that protective layer 14 reduces the amount of graphite formed by creating structure 12 with laser 10. Diamond membrane 2 has a thickness Ti, which in the illustrated embodiment is 60 micrometers.

[0056] Diamond membrane 2 (figure 2B) is cleaned after creating structure 12 on first surface 4. Structure 12 can be any suitable structure on a diamond membrane that is used in quantum computers, quantum network end nodes and / or quantum sensors, such as a nanophotonic waveguide, an optical resonator or a photonic crystal cavity. In particular, at least first surface 4 of diamond membrane 2 has been cleaned. The cleaning step removes protective layer 14 from first surface 4. Alternatively, or additionally, the cleaning step may remove irregularities caused by the laser cutting. In the illustrated embodiment, first surface 4 has been cleaned by a boiling triacid solution. It is clear for the skilled person that any cleaning method which removes the irregularities caused by the laser cutting is suitable for the present disclosure. After cleaning, pattern 12 remains in first surface 4. Diamond membrane 2 has a thickness Ti, which in the illustrated embodiment is 60 micrometers.

[0057] Diamond membrane 102 (figure 3 A) comprises first surface 104. On first surface 104 pattern 112 is created. Pattern 112 is created by applying laser light from laser 10 on first surface 104. The laser light from laser 10 will cut into first surface 104, thereby creating pattern 112. Before applying the laser light from laser 10 on first surface 104, protective layer 114 was applied on first surface 104. Protective layer 114 in this illustrated embodiment is chromium. It is clear for the skilled person that protective layer 114 could also be the PVA layer as described in figure 2A. Furthermore, combinations of materials are possible for protective layer 114. For example, a mixture between chromium and PVA can be applied to form protective layer 114. In another example, protective layer 114 comprises a plurality of layers each of a different material. It may be possible that a first layer comprises PVA and a second layer comprises chromium, wherein the first and the second layer together form protective layer 114. Diamond membrane 102 has a thickness Ti, which in the illustrated embodiment is 60 micrometers.

[0058] First surface 104 (figure 3B) has been cleaned by a boiling triacid solution. It is clear for the skilled person that any cleaning method which removes the irregularities caused by the laser cutting is suitable for the present disclosure. After cleaning, pattern 112 remains in first surface 104. Diamond membrane 102 has a thickness Ti, which in the illustrated embodiment is 60 micrometers.

[0059] First surface 104 (figure 3C) has been etched. In this illustrated embodiment, first surface 104 has been etched by reactive ion etching. An example of reactive ion etching will be further explained in figure 4. By etching first surface 104, first surface 104 is cleaned and smoothened. In an example first surface 104 may be etched such that a few micrometers of material is removed from first surface 104. After etching, pattern 112 remains in first surface 104. Diamond membrane 2 has a thickness T2, which in the illustrated embodiment is 57 micrometers.

[0060] Reactive ion etcher 120 (figure 4) is based on inductively coupled plasma reactive ion etching (ICP RIE). Reactive ion etcher 120, which may be an Oxford etcher, a Sentech SI 500 etcher or a Unaxis ICP etcher, comprises housing 126. Around upper part of housing 126 coil 122 is arranged. Coil 122 is operatively connected to power generator 124. Power generator 124 is configured to send a radio frequency signal to coil 122, such that coil 122 generates a strong radiofrequency (RF) electromagnetic field. Gas which enters housing 126 through opening 128 is ionized by stripping them of electrons, thereby creating plasma. The plasma exits housing 126 through exit tubes 130 which are connected to pump 132. Pump 132 pumps the gas out of housing 126, such that gas entering through opening 128 is moved towards exit tubes 130. Sample holder 134 is positioned in front of exit tubes 130 and thus inside housing 126. Sample holder 134 holds diamond membrane 104. In this illustrated embodiment, fused quartz mask 136 is arranged on second surface 106 of diamond membrane 102. Plasma that is created above sample holder 134 flows into the direction of sample holder 134 and on diamond membrane 102, thereby etching diamond membrane 102. Any suitable gas for etching can be introduced in housing 126, such as argon, chlorine and / or oxygen.

[0061] It is clear for the skilled person that the reactive ion etching as explained in relation to figure 4 is just one embodiment of the available dry etching techniques that can be used for the present disclosure. Other dry etching techniques are also included in the present disclosure. Diamond membrane 102 has a thickness T2, which in the illustrated embodiment is 57 micrometers. Due to the etching of the ions of the plasma, recesses 137 are created in diamond membrane 2. Thickness T3 of diamond membrane 102 between first surface 104 and recesses 137 is in the illustrated embodiment 5 micrometers. In this way, the material on second surface 106 that surrounds recesses 137 can be seen as a frame for handling diamond membrane 102.

[0062] In an embodiment diamond membrane 102 may be etched without mask 136 present on second surface 106. In that case, whole second surface 106 may be removed such that all of diamond membrane 102 acquires thickness T3 of 5 micrometers.

[0063] In an embodiment according to the present disclosure in step 240 (figure 5) diamond membrane 102 is provided. Diamond membrane 102 comprises first surface 104 and second surface 106. In step 242 structures 112 are creating in diamond membrane 102. Structures 112 may be created by applying light from laser 10 to first surface 104 of diamond membrane 102. In step 244 second surface 106 of diamond membrane 102 is dry etched. By dry etching second surface 106 a thickness of diamond membrane 102 can be reduced. The thickness may be reduced over the whole second surface 106. Alternatively, mask 136 may be arranged on second surface 106 such that only part of second surface 6 is removed. This only partially reduces the thickness of diamond membrane 102.

[0064] In an embodiment according to the present disclosure step 346 (figure 6) comprises arranging protective layer 114 on diamond membrane 102. Protective layer 114 is arranged on first surface 104 of diamond membrane 2. Protective layer 114 may comprise PVA and / or chromium. Step 348 comprises applying laser light on diamond membrane 102 to create structures 114. The laser light may be applied by femtosecond-pulsed laser 10. Structures 114 may be created on first surface 104 of diamond membrane 102. After creating structures 114, diamond membrane 102 may be cleaned in step 350. In an embodiment, cleaning diamond membrane 102 comprises removing protective layer 114 from first surface 104. Step 150 may comprise applying boiling triacid solution on diamond membrane 102, preferably on its first surface 104, such that any imperfections on diamond membrane 104 are removed. Step 352 comprises dry etching first surface 104 of diamond membrane 102. Dry etching first surface 104 may comprise the reactive ion etching of first surface 104, for example with the reactive ion etcher 120 from figure 4. Step 352 may reduce the thickness of diamond membrane 102 by a few millimetres and to smooth first surface 104. Step 354 comprises arranging a mask 136 on diamond membrane 102. Step 354 is optional. Mask 136 preferably is a fused quartz mask. Mask 136 may be arranged on second surface 106 of diamond membrane 102. Step 356 comprises dry etching second surface 106 of diamond membrane 102. Dry etching second surface 106 may comprise the reactive ion etching of first surface 104, for example with the reactive ion etcher 120 from figure 4. Mask 136 protects part of second surface 106 from dry etching. This ensures that the part of second surface 106 that is protected by mask 136 keeps the thickness before the dry etching of step 356. In this way, it can be ensured that diamond membrane 102 does not break during handling of diamond membrane 102. The part of second surface 106 that is not protected by mask 136 is dry etched in step 356, thereby reducing the thickness thereof. The present invention is by no means limited to the above described preferred embodiments thereof. The rights sought are defined by the following clauses within the scope of which many modifications can be envisaged.

Claims

CLAIMS1. Method for producing diamond membranes with structures for use in quantum systems and / or quantum sensors, comprising: providing a diamond membrane that comprises a first surface and a second surface; creating structures in the diamond membrane by applying light from a laser to the first surface of the diamond membrane; and dry etching the second surface of the diamond membrane to reduce a thickness of the diamond membrane.

2. Method according to claim 1, wherein the structures comprise 3D-structures formed by the removal of material.

3. Method according to claim 1 or 2, wherein the structures comprise an absence of material below the first surface of the diamond membrane.

4. Method according to any one of the foregoing claims, further comprising: arranging, prior to the step of creating structures in the diamond membrane, a protective layer on the first surface of the diamond membrane.

5. Method according to any one of the foregoing claims, wherein the protective layer is present on the first surface during the step of creating structures in the diamond membrane.

6. Method according to claim 4 or 5, wherein the protective layer comprises a polymer, such as polyvinyl alcohol (PVA), and / or a metal, such as chromium.

7. Method according to any one of claims 4-6, wherein a thickness of the protective layer is in the range of 10 nanometres - 10 micrometres, preferably in the range of 100 nanometres - 5 micrometres, and most preferably in the range of 150 nanometres - 2 micrometres.

8. Method according to any one of the foregoing claims, wherein the step of creating structures in the diamond membrane comprises creating trenches and / or slits in the diamond membrane.

9. Method according to any one of the foregoing claims, further comprising:dry etching the first surface of the diamond membrane after the step of creating structures in the diamond membrane.

10. Method according to claim 9, wherein the dry etching comprises reactive ion etching (RIE).

11. Method according to claim 10, wherein the reactive ion etching comprises: creating a plasma that comprises argon and / or chlorine; applying the charged ions of the argon and / or chlorine to the first of the diamond membrane; creating a second plasma that comprises oxygen; and applying the charged ions of the oxygen to the second surface of the diamond membrane.

12. Method according to any one of the foregoing claims, wherein the step of dry etching the second surface comprises reactive ion etching (RIE).

13. Method according to claim 12, wherein the reactive ion etching comprises: creating a plasma that comprises argon, chlorine and / or oxygen; and applying the charged ions of the argon, chlorine and / or oxygen to the second surface of the diamond membrane.

14. Method according to claim 12, wherein the reactive ion etching comprises: creating a first plasma that comprises argon and / or chlorine; applying the charged ions of the argon and / or chlorine to the second surface of the diamond membrane; creating a second plasma that comprises oxygen; and applying the charged ions of the oxygen to the second surface of the diamond membrane.

15. Method according to any one of the foregoing claims, further comprising: arranging a mask, for example a mask of fused quartz, on the second surface of the diamond membrane before dry etching the second surface.

16. Method according to any one of the foregoing claims, further comprising:cleaning the first surface of the diamond membrane by applying an inorganic fluid, for example a boiling triacid solution, to the first surface of the diamond membrane.

17. Method according to any one of the foregoing claims, wherein the laser is a femtosecond- pulsed laser.

18. Method according to any one of the foregoing claims, wherein the first surface and the second surface of the diamond membrane are oppositely arranged.

19. Method according to any one of the foregoing claims, wherein the thickness of the diamond membrane prior to the steps of creating structures and dry etching is in the range of 20-200 micrometres, preferably in the range of 50-100 micrometres, and most preferably in the range of 50-70 micrometres, for example 60 micrometres.

20. Method according to any one of the foregoing claims, wherein the thickness of the diamond membrane after the steps of creating structures and dry etching is in the range of 0.05-50 micrometres, preferably in the range of 0.1-20 micrometres, and most preferably in the range of 0.1-10 micrometres, for example 5 micrometres.

21. Method according to any one of the foregoing claims, wherein a depth of the structures in the diamond membrane is in the range of 1-50 micrometres, preferably in the range of 3-20 micrometres, and most preferably in the range of 5-15 micrometres, for example 10 micrometres.

22. Method according to any one of the foregoing claims, wherein a spot size of the light from the laser is in the range of 0.1-5 micrometres, preferably in the range of 0.5-2 micrometres, and most preferably is in the range of 0.8- 1.5 micrometres, for example 1 micrometre.

23. Diamond membrane obtained by the method according to any one of the foregoing claims.

24. Quantum system comprising a diamond membrane according to claim 23.

Images