Method for producing a layer structure and microstructural component
Patent Information
- Application Number
- PCT/EP2026/054702
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-13
- Filing Date
- 2026-02-20
- Publication Date
- 2026-09-17
Smart Images
Figure EP2026054702_17092026_PF_FP_ABST
Abstract
Description
[0001] R. 417648
[0002] - 1 -
[0003] Description
[0004] title
[0005] Method for producing a layered structure and microstructural component
[0006] The invention relates to a method for producing a layered structure according to claim 1. Furthermore, the invention relates to a microstructural component with such a layered structure.
[0007] State of the art
[0008] In DE 102020211 354 A1 a thin-film device with passivation layer is described, which is designed as a hydrogen barrier, for example made of aluminium oxide and is applied by sputtering or an evaporation process.
[0009] Disclosure of the invention
[0010] According to the present invention, a method for producing a layered structure with the features of claim 1 is proposed. This allows the application of a pore-free, dense, and amorphous barrier layer. Diffusion of hydrogen through the barrier layer can be reduced or prevented. The degree of contamination of the barrier layer can be reduced. The number of defects in the barrier layer can be reduced.
[0011] The microstructural component can be a micromechanical, microelectrical, or microelectromechanical component. The microelectromechanical component can be a pressure sensor. The pressure sensor can be a capacitive pressure sensor, in particular an absolute pressure sensor. R. 417648
[0012] - 2 -
[0013] The support layer can be at least partially composed of silicon or another material. The support layer can be a substrate or a layer applied to a substrate.
[0014] The barrier layer can also be called a barrier layer. In addition to the first and second layers, the barrier layer can comprise at least one further layer. The barrier layer can limit or prevent the diffusion of gas, particularly hydrogen, through it. This limits or prevents the transfer of gas, especially hydrogen, from the top to the bottom of the barrier layer.
[0015] The barrier layer can be applied partially or completely to a surface of the substrate. The barrier layer can cover other layers, for example, a layer surrounding the substrate. The barrier layer can be applied directly to the surrounding layer. The barrier layer can consist of more than two layers. Plasma treatment can preferably be performed each time before the application of the next layer.
[0016] Plasma treatment can cause the first layer to be removed. The thickness of the first layer can be reduced by plasma treatment. Layer removal by plasma treatment can preferably be carried out on the previous layer before the next layer is applied.
[0017] The top side is preferably the side of the layer facing away from the support layer.
[0018] The plasma treatment performed between the application of the first and second layers improves the surface quality of the second layer. After plasma treatment, particularly after material removal from the top of the first layer, the first layer can serve as an ideal seed layer for the growth of the second layer. The surface of the first layer after plasma treatment can be smoother and exhibit a more uniform surface energy level. Furthermore, the first layer can be R. 417648
[0019] - 3 -
[0020] exhibit fewer impurities and / or defects, such as pores or crystallization areas, on the surface of the otherwise amorphous material structure.
[0021] The coating process may include a sequence of plasma treatment of the top surface of the uppermost layer, for example the second layer, repeated at least once, and the application of another layer of the coating material or another coating material to the surface of the previous layer treated by the plasma process.
[0022] The individual steps of applying the first layer, plasma treatment and applying the second layer can be carried out in this order.
[0023] Optionally, after the application of the second and / or last layer, additional material can be removed from the top of the second and / or last layer of the barrier layer to remove impurities and / or defects, such as pores or crystallization areas.
[0024] The layer structure can include, at least in some areas, a further layer on the barrier layer, in particular an insulating layer, i.e., an electrically insulating layer. This further layer can be composed, at least partially, of silicon nitride, silicon oxide, metal, metal silicide, metal nitride, metal oxide, silicon oxynitride, and / or silicon carbide. The further layer can be deposited by a chemical vapor deposition process, for example, plasma-enhanced chemical vapor deposition (PECVD), low-pressure chemical vapor deposition (LPCVD), atmospheric pressure chemical vapor deposition (APCVD), and / or atomic layer deposition (ALD), or by a physical vapor deposition process.
[0025] In a preferred embodiment of the invention, it is advantageous if the layer thickness of the first layer, particularly after plasma treatment, is between 2 nm and 100 nm, particularly between 5 nm and 80 nm, and particularly between 35 nm and 75 nm. The layer thickness can be an average layer thickness. R. 417648
[0026] - 4 -
[0027] The thickness of the first layer can be less than, equal to, or greater than the thickness of the second layer.
[0028] The thickness of the first layer may deviate by less than 50%, in particular by less than 20%, from the thickness of the second layer in the fully constructed barrier layer.
[0029] The thickness of the barrier layer, in particular the mean thickness, can be between 10 nm and 500 nm, in particular between 50 nm and 400 nm, in particular between 100 nm and 300 nm, preferably between 150 nm and 250 nm.
[0030] The deposition rate (growth rate), as depositionable (growable) layer thickness per unit of time, of the coating process, in particular for the production of the first layer, the second layer and / or a further layer, can be greater than or equal to 1 nm per minute, preferably greater than or equal to 2 nm per minute, in particular greater than or equal to 5 nm per minute, in particular greater than or equal to 10 nm per minute, in particular greater than or equal to 20 nm per minute, in particular greater than or equal to 30 nm per minute.
[0031] In a preferred embodiment of the invention, it is advantageous if the barrier layer material comprises at least some aluminum oxide and / or silicon nitride. The barrier layer can be composed entirely of this material. This ensures that the barrier function against the gas, particularly hydrogen, is reliably fulfilled. Alternatively or additionally, the barrier material can be composed at least some of aluminum nitride, titanium oxide, titanium nitride, zirconium oxide, and / or silicon carbide.
[0032] In a preferred embodiment of the invention, it is advantageous if the application of the first and second layer layers and the plasma treatment are carried out under a maintained vacuum. This improves the quality of the barrier layer and simplifies and speeds up the manufacturing process. The vacuum supply does not need to be interrupted.
[0033] A preferred embodiment of the invention is advantageous in which the coating process is a physical coating process, in particular R. 417648
[0034] - 5 -
[0035] A physical vapor deposition process is or includes sputtering. The physical coating process may include sputtering. The coating process may include or be a chemical vapor deposition process, for example, plasma-enhanced chemical vapor deposition (PECVD), low-pressure chemical vapor deposition (LPCVD), or atmospheric pressure chemical vapor deposition (APCVD).
[0036] In a preferred embodiment of the invention, the surface roughness of the top surface of the first layer is lower after plasma treatment than before plasma treatment. The surface roughness can be specified as the arithmetic mean roughness value Ra or as the mean roughness depth Rz.
[0037] In a preferred embodiment of the invention, it is advantageous if the plasma treatment comprises the removal of at least the first layer by bombarding the surface with ions of a plasma. The plasma can comprise ions of helium, argon, krypton, nitrogen, oxygen, or a combination of these substances.
[0038] In a specific embodiment of the invention, it is advantageous if the substrate layer, in particular its surface, is cleaned or prepared by plasma cleaning prior to coating. This allows unwanted layers, contaminants, and foreign substances on the substrate layer's surface to be removed before coating. Preferably, the plasma cleaning is performed without interrupting the vacuum immediately before coating the substrate layer's surface. The plasma cleaning can be or comprise a plasma treatment.
[0039] In a preferred embodiment of the invention, the plasma for both plasma cleaning and plasma treatment is provided by a common plasma device. The plasma for both cleaning and treatment can consist of ions of the same gaseous material.
[0040] According to the present invention, a microstructural component with the features of claim 10 is further proposed. The barrier layer can, at least in certain areas, comprise another layer, in particular a R. 417648
[0041] - 6 -
[0042] The material must have an insulating layer, i.e., an electrically insulating layer. The next layer can be composed, at least in part, of silicon nitride, silicon oxide, metal, metal silicate, metal nitride, metal oxide, silicon oxynitride, and / or silicon carbide. This next layer can be applied by chemical vapor deposition, for example, plasma-enhanced chemical vapor deposition (PECVD), low-pressure chemical vapor deposition (LPCVD), atmospheric pressure chemical vapor deposition (APCVD), and / or atomic layer deposition (ALD), or by physical vapor deposition.
[0043] Further advantages and advantageous embodiments of the invention will become apparent from the description of the figures and the illustrations.
[0044] Character description
[0045] The invention is described in detail below with reference to the illustrations. These show, in detail:
[0046] Figure 1: A cross-section of a microstructural component in a special embodiment of the invention.
[0047] Figure 2: A cross-section of a microstructural component in a further special embodiment of the invention.
[0048] Figure 3: A method for producing a layered structure in a special embodiment of the invention.
[0049] Figure 4: A cross-sectional view of a layer structure of a microstructural component in another specific embodiment of the invention for comparison.
[0050] Figure 1 shows a cross-section of a microstructural component in a specific embodiment of the invention. The microstructural component 10 is designed as a capacitive pressure sensor 12 and comprises a polysilicon diaphragm 14 which can be deflected into a cavity 16, in particular a cavern or cavity, depending on the fluid pressure of the area surrounding the diaphragm 14. The pressure sensor 12 is in particular an absolute pressure sensor and the cavity R. 417648
[0051] - 7 -
[0052] 16 is sealed against the environment 18, which has fluid pressure, by openings 20 in the membrane 14 or in the layer structure 22 covering the membrane 14. The layer structure 22 comprises a support layer 24 made of silicon oxide.
[0053] The layer structure 22 further comprises, above, here on the side of the support layer 24 facing away from the cavity 16, at least one electrical insulating layer 26, for example made of silicon nitride, which is applied in particular by plasma-enhanced chemical vapor deposition (PEVCD), for example by the use of silane, and thus represents a source of hydrogen, through which hydrogen atoms can enter the support layer 24 and through it into the cavity 16, increase the internal pressure in the cavity 16 and change the characteristic curve of the pressure sensor 12 and distort the measurement signal of the pressure sensor 12.
[0054] For this reason, the layer structure 22 between the support layer 24 and the insulating layer 26 includes a barrier layer 28 made of, for example, aluminum oxide, which serves in particular as a barrier against penetration, i.e., diffusion of hydrogen atoms from the insulating layer 26 to the support layer 24. The barrier layer 28 is produced by a physical deposition process, in particular by sputtering deposition, before the insulating layer 26 is applied to the support layer 24.
[0055] The barrier layer 28 is, in particular, completely deposited on the support layer 24. The barrier layer 28 is furthermore applied directly to the layer forming the membrane 14.
[0056] Figure 2 shows a cross-section of a microstructural component in a further specific embodiment of the invention. The microstructural component 10 comprises a microelectromechanical component 30 and an ASIC component 32, which is connected to the microelectromechanical component 30. Hydrogen atoms from the multilayer structure 34 of the ASIC component 32 can enter the space 36 formed when the microelectromechanical component 30 and the ASIC component 32 are connected, thereby impairing the sensor performance and sensor characteristics. R. 417648
[0057] - 8 -
[0058] Therefore, side 38 of the ASIC component 32 has a layer structure 22 with a support layer 24 and a barrier layer 28, the barrier layer 28 serving as a barrier against diffusion of hydrogen atoms from the layers above into the space 36.
[0059] Figure 3 shows a manufacturing process in a specific embodiment of the invention. The process for manufacturing a layer structure 40 for a microstructural component 10 comprises providing a support layer 24, for example, made of silicon, in particular polysilicon, or silicon oxide. At least partial coating 42 of the support layer 24 with a multilayer barrier layer 28 that at least limits hydrogen diffusion comprises first applying a first layer 44 of a layer material to the support layer 24 by a coating process 46, preferably physical, in particular sputtering. The layer thickness 48 of the first layer 44 is between 2 nm and 100 nm, in particular 50 nm. The layer material is preferably aluminum oxide and / or silicon nitride. The layer material is preferably applied by physical vapor deposition with sputtering.
[0060] After the first layer 44 is applied, at least one upper surface 52 of the first layer 44, facing away from the substrate 24, undergoes plasma treatment 50. The plasma treatment 50 comprises the removal of the upper surface 52 of the first layer 44 by bombardment with ions in a plasma 54, in particular with argon ions. After the plasma treatment 50, the layer thickness and surface roughness 56 of the first layer 44 are smaller than before the plasma treatment 50, and the surface 56 exhibits fewer defects, foreign atoms, and impurities.
[0061] Following plasma treatment 50, a second layer 58 of the same coating material as the first layer 44 is applied to the top surface 52, i.e., the side facing away from the substrate 24, of the first layer 44 by coating process 46. The smoothed and defect-reduced surface 56 of the first layer 44, created by plasma treatment 50, serves as a starting layer 60, a substrate for the second layer 58. (R. 417648)
[0062] - 9 -
[0063] The surface energy level of the first layer 44 can continue to be distributed more evenly across the surface 56.
[0064] The application of the first and second layer layers 44, 58 and the plasma treatment 50 are carried out, in particular, while maintaining a vacuum. Prior to coating 42, the substrate layer 24 can also be cleaned by plasma cleaning 62. A plasma 63 for plasma cleaning 62 and a plasma 54 for plasma treatment 50, including the plasma for coating 42, are provided by a common plasma device 64.
[0065] Figure 4 shows a cross-sectional view of a layered structure of a microstructural device in a further specific embodiment of the invention for comparison. The layered structure 22 of the microstructural device 10 in Figure 4a) is shown in comparison to a known layered structure 66 according to the prior art. The images were obtained with a transmission electron microscope and, in Figure 4b), show the support layer 24 and the barrier layer 28 conventionally applied to it by sputtering aluminum oxide, with a layer thickness 68 of approximately 200 nm. The defects 70, in particular pores and channels in the upper layer region, and the rough surface 67 of the barrier layer 28 are visible. The formation of pores and channels limits or reduces the barrier effect of the barrier layer 28 against the diffusion of hydrogen atoms through the barrier layer 28.A further increase in the thickness of the barrier layer 28 would not necessarily lead to an increase in the barrier effect.
[0066] In contrast, the barrier layer 28 made of aluminum oxide on the support layer 24 shown in Figure 4 a) has no defects and a smoother and denser surface 67, and can therefore form a reliable barrier against the diffusion of hydrogen atoms. The barrier layer 28 has a layer thickness 68 of approximately 200 nm, with the first layer 44 having a layer thickness of approximately 50 nm and the second layer 58 having a layer thickness 74 of approximately 150 nm.
[0067] Plasma treatment and the resulting removal of the surface layer of the first layer 44 can lead to the formation of pores and R. 417648
[0068] - 10 -
[0069] Impurities, defects, and / or germs that cause problems in the channels are removed, and a thicker, nearly defect-free barrier layer 28 with reliable barrier properties against the diffusion of, for example, hydrogen atoms is produced. By applying several plasma treatments during the production of the barrier layer 28, virtually arbitrarily thick, pore- and defect-free barrier layers 28 made of, for example, aluminum oxide can be advantageously applied.
Claims
R. 417648 - 11 - Patent claims 1. Method for producing (40) a layer structure (22) for a microstructural device (10), comprising the steps Providing a carrier layer (24), Coating (42) of the carrier layer (24) with a multilayer barrier layer (28) that at least limits the diffusion of a gas, comprising the individual steps Applying a first layer (44) of a layer material to the substrate (24) by a coating process (46), plasma treatment (50) on at least one upper surface (52) of the first layer (44) facing away from the substrate (24) and Applying a second layer (58) of the coating material or another layer material to the top (52) of the first layer (44) by the coating process (46).
2. Method for production (40) according to claim 1 , characterized in that the layer thickness (48) of the first layer (44) is between 2 nm and 100 nm.
3. Method for production (40) according to claim 1 or 2, characterized in that the layer material comprises at least partially aluminium oxide and / or silicon nitride.
4. A method for production (40) according to one of the preceding claims, characterized in that the application of the first and second layer layers (44, 58) and the plasma treatment (50) are carried out under a maintained vacuum. R. 417648 - 12 - 5. Method for production (40) according to one of the preceding claims, characterized in that the coating method (46) is a physical vapor deposition.
6. Method for production (40) according to one of the preceding claims, characterized in that the surface roughness of a surface (56) of the top side (52) of the first layer (44) after plasma treatment (50) is smaller than before plasma treatment (50).
7. Method for production (40) according to one of the preceding claims, characterized in that the plasma treatment (50) comprises layer removal of at least the first layer layer (44) by bombarding the top surface (56) with ions of a plasma (54).
8. Method for production (40) according to one of the preceding claims, characterized in that the carrier layer (24) is cleaned by plasma cleaning (62) before coating (42).
9. Method for production (40) according to claim 8, characterized in that the plasma (54) is provided by a common plasma device (64) for both the plasma cleaning (62) and the plasma treatment (50).
10. Microstructural component (10) comprising at least one carrier layer (24) and a barrier layer (28) applied thereto by a manufacturing process (40) according to one of the preceding claims.