Method and apparatus for the in-situ structured deposition of three-dimensional micro- and / or nanostructures on a substrate

Abstract

A method and a device for the in-situ structured deposition of three-dimensional micro- and / or nanostructures (20) on a substrate (30) by means of ion beam etching through a mask (50) are described, wherein the method (100) comprises: providing the mask (50), which comprises a first layer (51) with at least one channel (60) in which material (62) to be removed is arranged, or at least two layers (51, 52), wherein the first layer (51) comprises at least one channel (60) in which material (62) to be removed is arranged, and a second layer (52) which spans the first layer (51) in the form of a perforated membrane (70); arranging the mask (50) above a substrate (30) to be coated; arranging the mask (50) with the substrate (30) to be coated in an ion beam etching system (40);subsequent creation of a vacuum in the ion beam etching system (40) to cause the ion beam to penetrate the at least one channel (60) under vacuum and for the material physically removed by the ion beam to strike the substrate (30) as coating material (62).

Description

[0001] The present invention relates to a method and a device for the in-situ structured deposition of three-dimensional micro- and / or nanostructures on a substrate.

[0002] In the field of semiconductor / microsystems technology, the fabrication of a structured layer of a defined material on a substrate is a recurring task with a sometimes high degree of complexity, depending on the material. The methods commonly used involve complex process sequences, each requiring specific techniques and equipment.

[0003] Apart from special cases where selective deposition is possible due to chemical compatibility between the substrate and the material to be deposited, a non-selective deposition process in combination with a lithography step is generally used to produce a structured layer. Deposition can be achieved using various methods such as chemical vapor deposition (CVD), atomic layer deposition (ALD), or physical vapor deposition (PVD). However, not every material can be deposited onto a substrate using the same of the aforementioned deposition methods, so individual process parameters and deposition methods are developed, or have been developed, depending on the material properties.

[0004] The preparation for structuring is carried out using lithography. This involves creating a structured mask on the surface of the material, which serves as a template for subsequent processing steps. For example, in so-called lift-off processes, a material is deposited onto a lithographically structured photoresist mask; however, in most cases, a photoresist mask is applied only after a deposition process to serve as a mask in a subsequent etching step.

[0005] After lithography, the photoresist mask structure is transferred to the deposited material via an etching process. In this step, the material is selectively removed from the areas not masked by the photoresist, creating the desired pattern. However, the etching methods used are not universal and vary depending on the material (for example, chlorine chemistry for metals and fluorine chemistry for oxides).

[0006] When three-dimensional structures are to be produced from different materials, the entire process of deposition, lithography, and etching must be repeated multiple times. This repetitive cycle significantly increases the complexity, time, and cost of the manufacturing process, as each material requires its own set of deposition and etching techniques. Furthermore, producing freeform objects using these conventional methods is extremely challenging. Even when processing multiple successive layers, creating complex and irregular shapes remains a major hurdle. The edge and flank angles of the structured materials are largely determined by the interplay between the edge angle of the photoresist and the selectivity between the material being structured and the photoresist during the etching process.Furthermore, the edges of the photoresist at the boundary to the layer to be structured are transferred into this layer, so that the production of continuous, smooth transitions of materials that are intended to function as free-form bodies in a microelectronic component is generally not possible.

[0007] The aforementioned technological hurdles in the production of freeform bodies with smooth structural transitions to the underlying substrate necessitate innovative manufacturing processes. These requirements arise, for example, in the production of microlenses and other optical components.

[0008] Stencil lithography, or deposition using a shadow mask, offers potential solutions to some of the challenges encountered in conventional microsystems engineering methods for producing structured layers.

[0009] In stencil lithography, a shadow mask with structured openings is placed between the deposition source and the substrate. The material is then deposited through these openings, creating the desired pattern on the substrate. This allows for the creation of a precise structure in a single process step, eliminating the need for the deposition, lithography, and etching cycle described earlier. This process eliminates multiple steps, including equipment and expertise, reducing the overall complexity and cost of the manufacturing process. Furthermore, the stencils or shadow masks can be reused for multiple materials. However, individual deposition techniques for each desired material remain necessary. Additionally, the material to be deposited can also be deposited directly onto the masks themselves.During deposition, the openings of the mask can consequently narrow or even become blocked, resulting in uneven or incomplete deposition on the substrate.

[0010] Area-selective deposition (ASD) using chemical vapor deposition (CVD) or atomic layer deposition (ALD) also combines the deposition and structuring of a layer in a single step. However, this process usually requires a predefined structure on the substrate, so several processing steps are necessary before ASD.

[0011] However, neither of the aforementioned methods (stencil lithography and ASD) represent universal deposition processes, are generally not suitable for all materials and require specially designed reactor types.

[0012] One object of the present invention is to provide a method and a device with which, similar to stencil lithography, any materials can be structured and deposited in-situ in a semiconductor manufacturing plant during only one process step.

[0013] This problem is solved by the subject matter of the attached independent claims.

[0014] A method for the in-situ structured deposition of three-dimensional micro- and / or nanostructures onto a substrate using ion beam etching through a mask is proposed. The proposed method comprises providing a mask that includes a first layer with at least one channel in which the material to be removed is arranged, or at least two layers, wherein the first layer includes at least one channel in which the material to be removed is arranged, and a second layer that spans the first layer in the form of a perforated membrane. The second layer is defined by the perforated membrane. The proposed method includes positioning the mask above a substrate to be coated. Furthermore, the method includes positioning the mask and the substrate in an ion beam etching system.Subsequently, a vacuum is created in the ion beam etching system to allow the ion beam to penetrate the at least one channel under vacuum and deposit the material physically ablated by the ion beam onto the substrate as coating material (62). The vacuum is created by operating the ion beam etching system. During this process, the ion beam enters the mask to ablate material from the first layer and then deposit it onto the substrate. Some ions only pass through part of the channel because they collide with the side wall of the mask and the material to be deposited within the channel.

[0015] The proposed method uses an ion beam etching system and a special mask to selectively and locally deposit thin layers or three-dimensional micro / nanostructures of any material onto a substrate in just one process step.

[0016] The proposed method allows for the deposition of defined geometries in a single process step on a single system. The sputtering target and mask, particularly the shadow mask, are integrated into a single device, requiring only one process (ion beam etching) and one system for both different materials and geometries. Consequently, the know-how and equipment required for the method are significantly reduced compared to existing methods, provided the mask is already in place.

[0017] This type of selective deposition can be performed in a conventional ion beam etching system without any structural modifications if the mask is temporarily bonded or attached to the substrate. Alternatively, more precisely defined deposition processes are possible if the mask and substrate wafer are located in two separate holders, the distance between which can be freely adjusted as a process parameter.

[0018] Another aspect of the present invention relates to a mask which is designed to be used for the in-situ deposition of three-dimensional micro- and / or nanostructures on a substrate by means of ion beam etching, wherein the mask comprises: a first plane with at least one channel in which material to be removed is arranged or at least two planes, wherein the first plane comprises at least one channel in which material to be removed is arranged and a second plane which spans the first plane in the form of a perforated membrane.

[0019] Another aspect of the present invention relates to a device for depositing three-dimensional micro- and / or nanostructures onto a substrate by means of ion beam etching through a mask. The proposed device comprises a mask comprising a first layer with at least one channel in which material to be removed is arranged, or comprising at least two layers, wherein the first layer comprises at least one channel in which material to be removed is arranged and a second layer spans the first layer in the form of a perforated membrane. The mask is mounted on or in front of a substrate to be coated, with an ion source of an ion beam etching system arranged at a distance from the mask. The device is configured to direct an ion beam into the mask when the ion beam etching system is operated, in order to remove material from the first layer and deposit it onto the substrate.The device is therefore designed to generate a vacuum in the ion beam etching system in order to cause the ion beam to penetrate the at least one channel under vacuum and for the material physically removed by the ion beam to hit the substrate as coating material.

[0020] The mask serves as both a sputtering target and a shadow mask and consists of two layers: The first layer contains cavities or channels spanned by a perforated membrane – the second layer. The sidewalls of the cavities in the first layer are coated with the material to be deposited. This mask is then attached to the substrate to be coated, and the composite is processed in an ion beam etching system.

[0021] In the proposed method and use of the proposed device, the ion beam strikes the mask under vacuum and physically removes material from the sidewalls. The coating material, present in the gas phase, is then deposited onto the underlying substrate and forms three-dimensional micro- and / or nanostructures in situ.

[0022] Further advantageous embodiments of the present invention are the subject of dependent patent claims.

[0023] Preferred embodiments of the present teaching are described below in connection with the accompanying figures. It is understood that the described embodiments do not limit the scope of the teaching described herein. The figures show: Fig. 1a, b, c a schematic representation of the proposed method using the proposed apparatus in three variations: a) a perforated membrane is facing away from the substrate to be coated, b) a perforated membrane is facing towards the substrate to be coated; and c) a perforated membrane is facing both towards and away from the substrate to be coated; Fig. 2a, b, c Schematic representation of possible ion trajectories in Fig. 2a and schematic representation of the influence of the distance between mask and substrate on the geometry of the deposited structure in Fig. 2b and Fig. 2c; Fig. 3a, b Microscopy images of structures produced using the proposed method. Fig. 3a: Top view under a light microscope. Fig. 3b: Scanning electron microscope oblique view; Fig. 4 Fig. 4a: Light microscopic top view of a structure deposited using the proposed method. Fig. 4b: Light microscopic top view of the channel structure used for this purpose; Fig. 5 a schematic representation of the proposed method using the proposed device, wherein the mask does not include vertical side walls ( Fig. 5a and Fig. 5b); Fig. 6 A schematic view of four further phenomena when using the proposed method; including tilting of the substrate ( Fig. 6a and Fig. 6b) or change in the distance between ion sources and mask ( Fig. 6c); and Fig. 7. A flowchart of the proposed procedure.

[0024] The principle of the teaching disclosed herein will be further clarified below by means of possible embodiments, whereby the detailed description of individual embodiments does not constitute a limitation of the teaching described herein.

[0025] It should be noted that all figures are simplified representations and together form an overall picture of the proposed technical teaching. Each figure shows only one or two effects, if possible, to keep them simple and easy to understand. The figures are not to scale. Neither the representation of the ion beam as parallel arrows nor the representation of the ion source as a point is entirely accurate, but for the sake of simplicity, they are used here as is customary. Taken together, the accompanying figures provide a realistic illustration of the proposed technical teaching.

[0026] Individual aspects of the invention described herein are set forth below. Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6 to Fig. 7 described. In the present application, identical reference numerals refer to identical or equivalent elements, and it is not necessary for all reference numerals to be shown again in all drawings if they are repeated.

[0027] It should be noted that the ion beam and the ion source 42 are depicted in two different ways in the figures. In practice, the ion beams run almost parallel and do not originate from a point source. Nevertheless, in Fig. 6 c) The ion source is represented as a point. In practice, the ion beam is not perfectly parallel, but exhibits a slight beam divergence, causing it to fan out somewhat. This is exaggerated in the figures, which are not to scale, for illustrative purposes.

[0028] Fig. Figure 1 shows schematic representations of the proposed method using the proposed device in three variations. Fig. Figure 1a) shows a perforated membrane 70 facing away from the substrate 30 to be coated, so that an ion beam is modulated before the ion beam hits the coating material 62 and subsequently the substrate 30. Fig. Figure 1b shows a perforated membrane 70 facing the substrate 30 to be coated, such that the coating material 62 is first removed from the side walls 61 of the channel 60 by the ion beam, and the material flow that strikes the substrate 30 to be coated is only subsequently modulated. In an arrangement as shown in Fig. As shown in Figure 1b, the deposition is also influenced by the shape of the openings 72a in the membrane 70. In an arrangement as shown in Figure 1b, the deposition is also influenced by the shape of the openings 72a in the membrane 70. Fig. As shown in Figure 1a, the shape of the openings 72a in the membrane 70 can also influence the deposition. In both cases, the size of the opening, i.e., the opening cross-section, is an important factor with regard to the deposition.

[0029] Fig. 1c shows a combination of the variants from Fig. 1a and Fig. 1b, i.e. Fig. Figure 1c shows two perforated membranes 70, one perforated membrane 70 facing the substrate 30 to be coated and the other perforated membrane facing away from the substrate 30 to be coated. A [missing text] can be produced in Fig. The mask 50 shown in Figure 1c, for example, can be created by connecting two individual masks 50, each of which has only one perforated membrane 70. The perforated membranes 70 are made of Fig. 1c can have perforations that are offset from each other (as in Fig. 1c shown). It is also conceivable that the perforations of the membranes 70 are not offset from each other (not shown).

[0030] The at least one channel 60 can also be configured as a cavity. The channel 60 can therefore also be created by the ion beam, which removes material from the cavity. For example, the channels 60 of the first level and the openings 72a of the second level 52 could be separated from each other by a thin layer. This layer could then be etched by the ion beam in the actual process, so that the channels 60 of the first and second levels 51, 52 are connected. Furthermore, it is conceivable that one or more columns are located within the channel 60 parallel to the side wall 61 of the channel 60, the surface of which also provides material 62 to be removed.

[0031] The Fig. Figures 1a to 1c, 2a to 2c, 5a and 5b, 6a to 6c, schematically show the proposed method 100, wherein Fig. Figure 7 shows a flowchart of the proposed method 100. The proposed method 100 is suitable for the in-situ structured deposition of three-dimensional micro- and / or nanostructures 20 on a substrate 30 by means of ion beam etching through a mask 50, requiring only a single process step. In step 120, the proposed method 100 first comprises providing the mask 50. The mask 50 comprises a first layer 51 with at least one channel 60 in which the material to be removed 62 is arranged. Fig. 1a and Fig. In 1b, two channels 60 are shown, while in the Fig. Figures 1c, 2a to 2c, 5a and 5b, and 6a to 6c each show only one channel 60. "At least one channel 60" can refer to one channel 60, two, or more than two channels 60. The mask 50 can comprise only the first layer 51, which is not shown in the figures. Alternatively, the mask 50 comprises at least two layers 51 and 52, wherein the first layer 51 comprises at least one channel 60 in which material 62 to be removed is arranged, and a second layer 52 spans the first layer 51 in the form of a perforated membrane 70. The second layer is configured as the perforated membrane 70. Fig. 1a, 1b, 2a to 2c, 5a and 5b, 6a to 6c each show a mask 50 with two levels 51, 52. Fig. 1c shows a mask with three levels (51, 52), where the mask is made of Fig. 1c comprises one layer 51 and two layers 52 in the form of perforated membranes 70. It is conceivable that the mask 50 comprises not only two second layers 52 but also two first layers 51. One can be manufactured in Fig. The mask 50 shown in Figure 1c can be created, for example, by connecting two individual masks 50, each of which has only a first layer 51 and a second layer 52. Furthermore, it is conceivable that a perforated membrane 70 is not arranged at an outer end of the mask 50, but rather centrally between the two first layers 51 (not shown in the figures). In step 130, the method 100 comprises arranging the mask 50 above a substrate 30 to be coated, in particular on which three-dimensional micro- and / or nanostructures 20 are to be deposited in situ using the mask 50. In step 140, the method 100 comprises arranging the mask 50 with the substrate 30 to be coated in an ion beam etching system 40. Steps 130 and 140 are carried out sequentially. Finally, the single process step that leads to the in-situ deposition of three-dimensional micro- and / or nanostructures 20 is performed.In step 150, a vacuum is therefore created in the ion beam etching system 40 to cause the ion beam to penetrate the at least one channel 60 under vacuum and to deposit the material physically ablated by the ion beam as coating material 62 onto the substrate 30. In step 150, the operation of the ion beam etching system 40 is therefore intended to cause an ion beam to enter the mask 50 in order to ablate material 62 from the first layer 51 and then deposit it onto the substrate 30 as coating material 62.

[0032] In other words, the side walls 61 of the cavities or channels 61 of the first level 51 are coated with the material 62 to be deposited. This mask 50 is attached to the substrate 30 to be coated, and the composite of mask 50 and substrate 30 is processed in an ion beam etching system 40. Under vacuum, the ion beam strikes the mask 50 and physically removes material from the side walls 61. The coating material 62, which is present in the gas phase, is then deposited on the underlying substrate 20 (see, for example, [reference]). Fig. 2b and Fig. 2c). The openings 72, 72a in the two planes 51, 52 modulate the ion and coating material flow to generate the desired structure 20 on the wafer 30.

[0033] Method 100 comprises generating a vacuum in the ion beam etching system 40 to cause the ion beam to penetrate the at least one channel 60 under vacuum and to strike the substrate 30 with material 62 physically removed by the ion beam. Fig. Figures 1a to 1c indicate the ion beam system 40. However, a person skilled in the art understands that the mask 50 and the substrate 30 to be coated are arranged in the ion beam system 40 to cause the ion beam to penetrate the at least one channel 60 under vacuum and to strike the substrate 30 with material 62 physically removed by the ion beam.

[0034] After removal in the gas phase of the coating material 62, the coating material 62 is deposited on the substrate 30 in the form of three-dimensional micro- and / or nanostructures 20, such as in Fig. 2b and Fig. 2c can be seen. Fig. Figure 3 shows microscopy images of three-dimensional micro- and / or nanostructures 20 deposited using the proposed method. Fig. Figure 3a shows a light microscopic top view of the three-dimensional micro- and / or nanostructures 20. Fig. Figure 3b shows an oblique scanning electron microscope view of the three-dimensional micro- and / or nanostructures 20. The nanostructure 20 consists of Fig. 3b has a diameter of slightly more than 25 µm. The nanostructure 20 consists of Fig. 3b further exhibits the form of a three-dimensional Gaussian distribution. The openings 72a in the membrane 70 were circular and located above a channel 60. In other words, the mask 50 was as in Fig. 1a shown arranged.

[0035] Fig. Figure 4a shows a light microscopic top view of a structure 20 deposited using the proposed method 100. Fig. Figure 4b shows a light microscopic top view of the channel structure used for this purpose, i.e., the channels 60. The channels 60 had a circular cross-section, so that the channels were cylindrical.

[0036] The exact shape of the micro- and / or nanostructures 20 can be adjusted by modulating an ion current of the ion beam and / or by modulating a coating material current of the ablated coating material 62 by means of an opening cross-section 72 of an opening 71 of the at least one channel 60 and / or the number of openings 71 of the at least one channel (60) and / or the opening cross-section 72a of the openings 71a in the perforated membrane 70 and / or the number of openings 71a in the perforated membrane 70. The intensity of the ion current can be influenced by the number of openings 71, 71a in both the first level 51 and the second level 52 and / or by the size of the opening cross-sections 72, 72a in the first and / or the second level 51, 52, which in turn influences the deposited layer on the substrate 30, especially with regard to its shape and size. Fig. 2b and Fig. Figures 2c show two different forms of the deposited three-dimensional micro- and / or nanostructure 20 on the substrate 30.

[0037] Method 100 comprises adjusting the number and / or spacing and / or shape and / or dimensions of the at least one channel 60 in the first plane 51 to deposit at least one three-dimensional structure 20 on the substrate 30. By adjusting the number and / or spacing and / or shape and / or dimensions of the at least one channel 60 in the first plane 51, the material flow of the deposited coating material 62 can be influenced or modulated. Alternatively or additionally, Method 100 comprises influencing the intensity of the ion current. The intensity of the ion current can be determined, for example, based on the number of openings 71a in the perforated membrane 70 or in the perforated membranes 70 and / or based on the opening cross-sections 72a in the perforated membrane 70 or in the perforated membranes 70. In other words, the number, spacing, shape, and dimensions of the cavities orThe channels 61 of the mask planes 51, 52 can be selectively adjusted to create three-dimensional structures 20 on the substrate 30. The number and size of the membrane openings 72a, i.e., the opening cross-sections 72a in the perforated membrane 70, influence the intensity of the ion current through the channel 61 or through the mask 50, and thus the amount of material deposited. The size and arrangement of the channels 61 allow the positions and dimensions of the deposited layer of coating material 62 on the substrate 30 to be coated to be adjusted. The distance between the mask 50 and the substrate 30 allows the contour or surface profile of the deposited layer of coating material 62 to be influenced as a further degree of freedom.

[0038] It should be noted here that the ion current can also be modulated by the ion beam etching system (in relation to the plasma power, the accelerating voltage, etc.) before it reaches mask 50. This means that the ion current for selective deposition cannot be influenced solely by the described process, but also by the setting parameters of the ion beam etching system itself. However, it is well known to those skilled in the art that the intensity and energy of the ion current can also be influenced via process parameters of the ion beam etching system itself, which is why this will not be discussed further here.

[0039] As in Fig. As shown in Figure 1c, the process can include adding at least one further layer 51, 52 to the mask 50, which includes at least one channel 60 like the first layer 51 or is designed in the form of a perforated membrane 70 like the second layer 52. It is conceivable that several first layers 51 and / or several second layers 52 form the mask 50. The first layers 51 and the second layers 52 can be stacked in any order relative to each other. It is conceivable that the channels 60 of two first layers 51 are at least partially offset from each other. Depending on the structure 20 to be produced, the second layer 52 can be omitted or the mask 50 can be supplemented by further layers 51, 52. The order of the layers 51, 52 can also be varied to achieve further design freedom. The material 62 to be deposited, or coating material 62 referred to herein, can also be varied.

[0040] Method 100 can involve varying the sequence of levels 51, 52 during ion beam etching to achieve design freedom. Alternatively or additionally, method 100 can involve varying the material 62 to be deposited in one first or one second level 51, 52, or in the different first levels 51, i.e., those configured like the first level 51, to achieve design freedom.

[0041] Method 100 can perform multilayer deposition of different coating materials 62 during a single deposition process on the substrate 30, coating at least one channel 60 along the channel 60 in reverse order (see, for example, Fig. 2a to 2c), and / or when coating different sections of the at least one channel 60 with the different coating materials 62 (see Fig. 6a, Fig. 6b). For example, the angle of incidence of the ion beam on a side wall 61 could be varied by tilting the mask 50, as shown in Fig. 6a and Fig. 6b, or by varying the distance between the ion source and the mask 50, as shown in Fig. 6c, or by the perforated membrane 70, through which the ion beam enters the channels 60, having geometries that cause the ion beam to be deflected, as shown in Fig. 2a is shown.

[0042] Method 100 can include fabricating the mask using microsystems technology, for example, from Si wafers. Mask 50 can be fabricated using established microsystems technology methods. These methods have already been published in another technical context [1], but can be used to fabricate mask 50 in the proposed technical teaching. Since this is known to those skilled in the art, it will not be discussed further here.

[0043] Method 100 can include arranging the mask 50 on or in front of the substrate 30 using temporary wafer bonds or a mask holder. To position the mask 50 with the substrate 30 to be coated such that the three-dimensional micro- and / or nanostructures 20 can be deposited on the substrate 30 by ion beam etching without the mask 50 slipping relative to the substrate 30, a temporary wafer bond or a mechanical mask holder can be used, in which the mask 50 can be fixed relative to the substrate 30.

[0044] As in Fig. As shown in 2a, the method 100 can comprise deflecting the ion beam by irregularities or by a geometric structure 73 in the perforated membrane 70 towards a side wall 61 of the at least one channel 60. As shown in Fig. As can be seen in Figure 2a, the geometric structure 73 is formed as an inclination in the perforated membrane 70. An opening cross-section 72a in the perforated membrane 70 on the side facing away from the first plane 51 is larger than on the side facing the first plane 51. The geometric structure 73 can have any shape suitable for deflecting the ion beam towards a side wall 61 of the at least one channel 60.

[0045] In the Fig. Figures 1a to 1c, 2a to 2c, 5a and 5b show that coating material 62 is applied to the side walls 61 of the channels 60 along their entire length. This coating material can be removed by ion beam etching. According to the Fig. In 6a to 6c, however, part of the coating material 62 forms part of the side wall 61. The side walls 61 themselves can also serve as coating material 62.

[0046] Method 100 can include influencing the surface profile of the deposited coating material 62 by adjusting the distance between the mask 50 and the substrate 30. In particular, the distance between the mask 50 and the substrate 30 can be mechanically adjusted using the mask holder. Fig. 2b and Fig. Figure 2c shows the influence of the distance between the mask 50 and the substrate 30. Fig. 2b the distance between the mask 50 and the substrate 30 is less than in Fig. 2c. As a final result, the three-dimensional micro- and / or nano-structure 20 deposited on the substrate 30 exhibits a flatter and wider geometry in the direction facing the mask when the distance between the mask 50 and the substrate 30 is greater (see Fig. 2c) than with a smaller distance between the mask 50 and the substrate 30 (cf. with the three-dimensional micro- and / or nano-structure 20 from Fig. 2b).

[0047] Method 100 can comprise adjusting a deposition rate of the coating material 62 on the substrate 30 by adjusting an angle of incidence of the ion beam on a side wall 61 of the at least one channel 60, wherein the angle of incidence is an angle β between a preferred direction 41 of the ion beam and the side wall 61. As, for example, in Fig. 5a and Fig. As can be seen in Figure 5b, the channels can be conically shaped. The angle of the side walls 61 of the conically shaped channel 60 allows the material removal from the channel 60, and thus the deposition rate on the substrate 30 to be coated, to be selectively increased or decreased. Such a conical hole can be created, among other things, in a silicon mask by wet chemical etching. Fig. In 5b, for example, channel 60 is oriented in a funnel shape with respect to the preferred direction 41 of the ion beam. As, for example, in Fig. As can be seen in Figure 2a, the ion beam can be inclined relative to the mask 50 so that it can strike the side wall 61, on which coating material 62 may be arranged and which can be removed by the ion beam, at its preferred direction 41 at an angle of incidence β. The present technical teaching utilizes the effect of partially elastic collisions. This means that the incident ion transfers a portion of its kinetic energy to the atoms / molecules of the wall material, which are then ejected at an angle. This (ejection) angle is close to the angle of incidence, but not necessarily identical. The incident ion, on the other hand, is scattered in any direction (according to conservation of momentum). If the ion beam strikes the coating material at its preferred direction 41, the ion beam is scattered in any direction. Fig. 6a and Fig. As can be seen in Figure 6b, the angle of incidence of the ion beam can be adjusted alternatively or additionally by tilting the substrate 30. The substrate 30, including the mask 50, can be tilted at different angles α1, α2, so that the preferred direction 41 of the ion beam can be aligned with the coating material 62 at different angles of incidence β1, β2.

[0048] It should be noted that the membrane 70 is also slightly etched by the ion beam. However, due to the kinematic component of the ion current, the material removed from the top surface of the membrane 70 tends to move away from the substrate, particularly in a reflection-like manner. Nevertheless, the material of the membrane 70, especially from the side walls of the perforations or openings 72a, can also contribute to the deposition.

[0049] The separation rate for a conical design of channel 60 as in Fig. 5a may be lower than with a cylindrical design of the channel 60. With a conical design of the channel 60 as in Fig. As shown in 5b, the separation rate can be higher than with a cylindrical design of channel 60 (as, for example, in Fig. 1a shown). If the side walls 61 run parallel to the preferred direction 41 of the ion beam (see Fig. 1a), only a few ions, which are not parallel due to the steel divergence, strike the side wall 61. If the side wall 61 is now tilted in the preferred direction 41 of the ion beam (see Fig. 5b), the numerous parallel ions can also collide with the side wall 61 and erode material 62. In the case as in Fig. As shown in 5a, only ions that deviate significantly from the preferred direction 41 or ions deflected by the perforated membrane 70 (or the irregularities or geometric structures contained therein) reach the side wall 61.

[0050] Fig. Figure 6 illustrates four further phenomena. Fig. It can be seen from sections 6a to 6c that the material 62 to be deposited can be defined not only by a coating of the side walls 61, but also by the mask substrate itself. Furthermore, the Fig. Figures 6a to 6c show that different materials can be deposited in a defined sequence using a multilayer mask substrate. Which material of a multilayer mask substrate is deposited at a specific time can be determined by tilting the substrate 30. This is illustrated in Figures 6a and 6b, where α1 > α2. Changing the distance between the mask 50 and the ion source 42 can also be used to control which material is deposited at which time.

[0051] As in Fig. As shown in Figure 6c, the method 100 can involve changing the distance between the mask 50 and the ion source 42 of the ion beam etching system 40 in order to adjust, particularly during ion beam etching, the point in time at which which coating material 62 is deposited on the side wall 61 of the at least one channel 60. Fig. Figure 6c shows that different coating materials 62 are attached to the side wall 61 at different positions. By changing the distance between the ion source 42 and the mask 50, the arrival position of the ion beam on the coating material can be altered, thus making the type of coating material 62 selectable. If the distance between the mask 50 and the ion source 42 is changed during ion beam etching, the point in time at which a specific coating material is first removed and then deposited on the substrate 30 can be determined during the ion beam etching process.

[0052] The proposed method 100 is suitable for both CMOS and post-CMOS fabrication, as the mask 50 can be made from CMOS-compatible materials. Furthermore, no temperatures occur during the deposition process that would preclude its use in post-CMOS process steps.

[0053] The mask 50 serves both as a sputtering target and as a shadow mask. In other words, the material from which the mask 50 is made can already be used as a coating material. As described herein, however, different coating materials 62 can also be introduced into the channels 60 of the mask 50. In particular, the mask 50 consists of two layers: The first layer 51 contains cavities or channels 61, which are spanned by a perforated membrane 70 – the second layer 52.

[0054] In the proposed method 100, the removal of the coating material 62 by ion beam etching can be replaced by vaporization using an electron beam, laser ablation, thermal heating, or the application of electric current. In other words, as an alternative to ion beam etching, the material 62 to be deposited can be removed from the mask using another method. It is also conceivable to modify the mask 50 so that it can be heated as a resistive element to vaporize the surface material. However, a disadvantage of these methods is that the material removed from the mask spreads in all directions by diffusion and would have to be guided to the substrate via a diffusion gradient. The advantage of the directed kinematic component of the atoms / molecules is only realized in combination with an ion beam. Therefore, ion beam etching is preferred.

[0055] A further aspect of the present invention relates to a mask designed for in-situ deposition of three-dimensional micro- and / or nanostructures 20 onto a substrate 30 by means of ion beam etching, wherein the mask 50 comprises: a first layer 51 with at least one channel 60 in which material 62 to be removed is arranged, or at least two layers 51, 52, wherein the first layer 51 comprises at least one channel 60 in which material 62 to be removed is arranged, and a second layer 52 which spans the first layer 51 in the form of a perforated membrane 70. The mask substrate, together with the channels 61, the perforated membrane 70 located above and / or below it, and the material 62 to be deposited on the channel walls 61, i.e., the side walls 62, forms the mask 50 described above.

[0056] The mask 50 described herein not only modulates the material flow to the substrate, but also simultaneously provides the coating material 62. The mask 50 represents a “structured target”.

[0057] The design of the mask 50 allows the material 62 to be deposited onto the substrate 30 in a structured manner, making subsequent structuring using material-specific etching processes merely optional. Depending on the application, the structured layer can function directly as an independent, functional layer within a semiconductor manufacturing process.

[0058] Another aspect of the present invention relates to a device 10 for the in-situ deposition of three-dimensional micro- and / or nanostructures 20 onto a substrate 30 by means of ion beam etching through a mask 50. The device 10 comprises a mask 50, which includes a first layer 51 with at least one channel 60 in which material 62 to be removed is arranged, or at least two layers 51, 52, wherein the first layer 51 includes at least one channel 60 in which material 62 to be removed is arranged and a second layer 52, which spans the first layer 51 in the form of a perforated membrane 70. The mask 50 is mounted on or in front of a substrate 30 to be coated. An ion source 42 can be arranged or is arranged at a distance from the mask.The device 10 is configured to generate a vacuum in the ion beam etching system 40 when the system is operated, in order to cause the ion beam to penetrate the at least one channel 60 under vacuum and to deposit material physically ablated by the ion beam as coating material 62 onto the substrate 30. In other words, the device 10 is configured to guide an ion beam into the mask 50 when the ion beam etching system 40 is operated, in order to ablate material 62 from the first layer 51 and deposit it onto the substrate 30.

[0059] The first level 51 comprises a plurality of channels 60, which extend essentially straight and vertically through the first level 51 to the substrate 30 and / or which have non-vertical side walls 61 along their extent through the first level 51. The channels 60 can be conical, in particular funnel-shaped, or essentially cylindrical. Reference is made to the preceding description of the mask's design, which is not repeated here.

[0060] The coating material 62 is provided by at least one coating of the side wall 61 of the at least one channel 60 and / or by at least one coating of the side wall 61 in the perforated membrane 70 and / or by the mask substrate of the first or second level 51, 52 itself. Using the proposed mask 50 or the proposed device 10, a three-dimensional micro- and / or nanostructure 20 can be deposited onto the substrate 30 by means of ion beam etching. For this purpose, it is possible to arrange different coating materials in the mask 50 in reverse order so that the different coating materials 62 can be deposited onto the substrate 30 in the correct sequence during ion beam etching. Alternatively or additionally, the different coating materials 62 can also be applied at different positions in the at least one channel 61.In other words, multilayer deposition of different materials on the substrate is possible if the cavities or channels 61 of the mask 50 are coated in reverse order. Thus, the process 100 offers the possibility of freeform structuring of virtually any material and its combinations.

[0061] The device 10 is designed to carry out a method 100 described herein.

[0062] The deposition of defined geometries in the technical teaching described herein occurs in a single process step on a single system. The sputtering target and shadow mask are combined in a single device, and only one process (ion beam etching) or system is required for both different materials and different geometries. Consequently, the know-how and equipment required for the application of the proposed method are significantly reduced compared to existing state-of-the-art methods, provided a mask is already in place.

[0063] This type of selective deposition can be performed in a conventional ion beam etching system without any design modifications if the mask 50 is temporarily bonded to the substrate. Alternatively, more precisely defined deposition processes are possible if the mask and substrate wafer are located in two separate holders, the distance between which can be freely adjusted as a process parameter.

[0064] Furthermore, the different levels 51, 52 in the mask 50 enable novel design freedom with regard to the geometry of the structures 20 to be deposited. By simply varying the number of holes in the membrane plane, for example, structures 20 of different heights but the same width can be deposited directly next to each other in the same process. While this is also possible with conventional stencil lithography (see Dynamic Stencil Deposition), it requires additional equipment for moving the mask during deposition. In addition, defined, three-dimensional, continuous freeform surfaces, i.e., micro and / or nanostructures 20, can be selectively produced in a single step.

[0065] The technical teaching described herein offers novel design freedom with regard to the material of the structures to be deposited. The ion beam used (i.e., Ar ions) can etch almost all materials, with only the etch rate varying. Consequently, the selection of the material to be deposited is almost unlimited, as long as the material can be applied to the side walls 61 of the channels 60 of the mask 50. The application of the material 62 to be deposited to the side walls 61 of the mask 50, for example, cannot be achieved exclusively by atomic layer deposition (ALD) or electroplating. Furthermore, it is possible to use a mask substrate made directly from the material 62 to be deposited, or to thermally oxidize the mask substrate before coating.

[0066] Multiple materials can be deposited in a single process step. A multi-layer coating of the mask cavities or channels 61 results in sequential deposition, whereas different coatings of multiple channels 61 lead to the parallel deposition of different materials.

[0067] Unlike conventional stencil lithography, clogging of the mask is impossible, as the ion beam continuously removes any deposited ions in the openings.

[0068] Overall, the proposed method can reduce costs and complexity while increasing flexibility with regard to detachable materials and their geometry on the substrate.

[0069] The technical teaching described herein in the field of coating technology in the context of semiconductor and microsystem technology manufacturing, based on the established stencil lithography process, offers significant advantages in several key areas, leading to a number of simplifications and new possibilities.

[0070] The most remarkable possibility offered by the selective vapor deposition (SCD) method presented here is the ability to create three-dimensional freeform surfaces from a wide range of materials. Conventional methods often struggle to produce complex and irregular shapes, especially when multiple layers are involved. In contrast, this proposed SCD method enables the precise and controlled deposition of three-dimensional structures. This opens up new possibilities for the design and fabrication of microsystems with intricate geometries and flat contours, enabling applications that demand a high degree of customization and functionality.

[0071] The proposed method also offers a more accessible technology compared to conventional methods. Since only one machine is required instead of several specialized devices, the barrier to entry for using this technology is significantly lowered. This improved accessibility allows a wider range of individuals and companies, including smaller businesses and research institutions, to utilize this form of selective vapor deposition and contribute to advancements in microsystems technology. The end user of this process only needs an ion beam etching system, as the mask fabrication can be flexibly outsourced to a supplier.

[0072] One promising application area is optics and photonics. The optimized stencil lithography, or the proposed method, can be used here for the fabrication of optical components, photonic devices, or diffractive elements. For example, microlenses with three-dimensional, smooth, continuous surfaces can be produced in a single process step.

[0073] Beyond optical components, further potential applications can be identified in the field of electrical and mechanical interfaces. The smooth, three-dimensional geometries can offer advantages as 3D electrodes for contacting biological and / or fluidic systems. In another example, smooth, continuous wave crests or fluidic barriers could be deposited on substrates for the production of microfluidics. Smooth edges can reduce turbulence, pressure losses, and erosion in fluidic systems. Further applications can be envisioned in the general field of MEMS manufacturing, as continuous and smooth material transitions, compared to conventionally sharp material edges, can avoid local peaks of mechanical stress, thus opening up new design freedoms.

[0074] These are just a few examples of the possible applications of an improved scraping ion lithography process or the selective vapor deposition presented here. The versatility of the technique makes it suitable for a wide range of industrial and research fields where precise and efficient material structuring is required.

[0075] Although some aspects have been described in connection with a process, it is understood that these aspects also constitute a description of a corresponding apparatus, such that a block or component of the apparatus can also be understood as a corresponding process step or as a feature of a process step. For reasons of redundancy, a complete description of the present invention in the form of apparatus features is omitted here.

[0076] In the preceding detailed description, various features were sometimes grouped together in examples to streamline the disclosure. This type of disclosure should not be interpreted as indicating that the claimed examples have more features than are expressly stated in each claim. Rather, as the following claims reflect, the subject matter may consist of fewer than all the features of a single disclosed example. Consequently, the following claims are hereby incorporated into the detailed description, with each claim potentially representing a separate, independent example.While each claim can stand as a separate example, it should be noted that, although dependent claims refer back to a specific combination with one or more other claims, other examples also include a combination of dependent claims with the subject matter of any other dependent claim, or a combination of any feature with other dependent or independent claims. Such combinations are included unless it is stated that a specific combination is not intended. Furthermore, it is intended that a combination of features of a claim with any other independent claim is also included, even if that claim is not directly dependent on the independent claim. literature

[0077] [1] [Brechmann et al.: CMOS-Compatible Hollow Nanoneedles With Fluidic Connection. Journal of Microelectromechanical Systems 2024. DOI 10.1109 / JMEMS.2024.3376991 and Brechmann et al.: Fabrication and characterization of CMOS-compatible perforated micromembranes for biomedical applications. Current Directions in Biomedical Engineering 2023. DOI 10.1515 / cdbme-2023-1110]. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited non-patent literature

[0000] Brechmann et al.: CMOS-Compatible Hollow Nanoneedles With Fluidic Connection. Journal of Microelectromechanical Systems 2024. DOI 10.1109 / JMEMS.2024.3376991

[0077] Brechmann et al.: Fabrication and characterization of CMOS-compatible perforated micromembranes for biomedical applications. Current Directions in Biomedical Engineering 2023. DOI 10.1515 / cdbme-2023-1110

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