Method for manufacturing an element having aluminum nitride and support substrate

Abstract

A method (600) for manufacturing a semiconductor device (100) having at least one exposed film portion is presented, the method (600) comprising the steps of: preparing a semiconductor material (102) having a support substrate (104) with a passivation film (108); applying a film layer (110) on the passivation film (108), wherein the film layer (110) is formed from an aluminum nitride material having an aluminum-to-nitrogen ratio in the range of 1.05 to 1.4; and applying a protective film (114) on the film layer (110). The side of the substrate opposite to the passivation film (108) is covered with a protective film (114), and the method includes: a step (620) of removing a portion of the support substrate (104) using a wet chemical method to obtain a substrate-free region (130) of the passivation film (108); and a step (630) of exposing a portion of the film layer (110) in the substrate-free region (130) using a first dry etching step to etch the passivation film and a second dry etching step to etch the protective film to obtain an exposed film portion (140).

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for manufacturing an element made of aluminum-rich aluminum nitride and having a film portion exposed on both sides according to the main claim.

Background Art

[0002] From the specification of Korean Patent Application Publication No. 1020210084381A, a film made of AlN, BN, or quartz is known. From the specification of Korean Patent Application Publication No. 1020180057813A, a phase shift mask having a metal nitride layer made of, for example, AlN is known. From the specification of Korean Patent Application Publication No. 1020180029384A, a film made of AlN and an element having such a film are known.

[0003] From the specification of German Patent Application Publication No. 102011005249A1, an apparatus for converting mechanical energy into electrical energy and a manufacturing method thereof are known. In that case, a manufacturing method of a curved piezoelectric film is described.

[0004] From JP 2013-160706A, a flow rate detection device on a semiconductor substrate having an exposed sensor region is known.

[0005] In the specification of German Patent Application Publication No. 102022111943B3, a method and a support substrate for manufacturing a semiconductor element are shown, and in that case, a film layer made of AlN is formed.

[0006] Modern semiconductor devices often require high flexibility in terms of material properties, which allows for good control of the light beam, for example, in optical semiconductor devices. In this invention, a semiconductor device can be understood as a device manufactured on a semiconductor substrate, such as a semiconductor wafer, or silicon wafer, as a support substrate. In this case, it is a mechanical and / or optical device, where the semiconductor properties of the substrate may not be important for its function. It may be a mechanical device, an optical device, or a device for the NIR, visible, UV, EUV, or X-ray electromagnetic wave regions. Such semiconductor devices can be manufactured using typical semiconductor industry techniques. However, the problem is that some advantageous material properties may belong to material types that are difficult to process. For example, some materials may have excellent, desirable material properties that are particularly advantageous at interfaces with other materials (such as air), such as high mechanical strength, high thermal conductivity, desirable electrical resistance, desirable modulus of elasticity, and / or a specific refractive index. Aluminum nitride has excellent properties for such applications as a thin-film material. The non-stoichiometric components of aluminum nitride allow for the modification of favorable material properties. However, because this material can be, for example, water-soluble or hydrolyzable, some process steps used in conventional semiconductor manufacturing methods cannot be used to process such materials. [Overview of the project] [Problems that the invention aims to solve]

[0007] Based on this challenge, we present a method that enables improved processing and, consequently, the manufacture of devices having thin, non-stoichiometric aluminum nitride films with improved properties. [Means for solving the problem]

[0008] This problem is solved by the subject matter of the main claim.

[0009] The approach presented herein provides a method for manufacturing a semiconductor device having at least one exposed film portion, the method comprising the following steps: a) A step of preparing a semiconductor material having a support substrate with a passivation film, b) A step of applying a film layer on a passivation coating, wherein the film layer is formed from an aluminum nitride material having an aluminum-to-nitrogen ratio in the range of 1.05 to 1.4. c) A step of applying a protective coating to a film layer, wherein the side of the film layer opposite to the passivation coating is covered by the protective coating. d) A step of removing a portion of the support substrate using a wet chemical method in order to obtain a substrate-free area of ​​the passivation coating, e) The method includes a step of exposing a portion of the film layer in an area without a substrate by using a first dry etching step for etching a passivation film and a second dry etching step for etching a protective film, in order to obtain an exposed film layer portion.

[0010] Advantageously, steps a to e can be performed in the order described. The exposed film layer portion can be exposed on both sides by completely removing the passivation film and protective layer in that portion. When etching the protective film, it is also possible to completely remove the protective film from the entire semiconductor material, or to remove it only partially, especially in the region where the exposed film layer portion is intended.

[0011] It is advantageous to perform a cleaning step with an aqueous cleaning agent, particularly a wet chemical cleaning method, before step e. In particular, the cleaning step can be performed after step d.

[0012] The exposed membrane layer can have a perforated structure, but this is not necessarily required.

[0013] The support substrate can be understood as a conventional substrate, for example, made of silicon. The support substrate may also be a single-crystal silicon wafer. This support substrate may have a passivation film containing silicon nitride or made of such a material.

[0014] A film layer is understood as a coating that has particularly advantageous properties, for example, with respect to its optical and / or mechanical properties, but the coating has materials that are changeable by water, especially hydrolyzable, in terms of its structure and / or composition, or is made of non-stoichiometric aluminum nitride material. For example, if the material comes into contact with water, or if a coating made of this material is damaged or cracked, the mechanical structure of the material may deteriorate. Hydrolysis is understood as the accumulation of water molecules, and in the event of evaporation or vaporization of water, the material may re-precipitation or crystallize. However, during hydrolysis, the material may also be chemically decomposed by contact with water. Aluminum nitride, for example, may be hydrolyzed while producing ammonia near the surface. Therefore, although aluminum nitride is quite resistant to the effects of water as a compact material or thick layer, if it is a thin layer, it can be rapidly destroyed by hydrolysis. In particular, thin layers made of non-stoichiometric aluminum nitride, especially thin layers with an excess of aluminum, are particularly susceptible to the effects of water. On the other hand, an excess of aluminum promotes the desired permanent tensile stress of the film in some applications.

[0015] This approach is based on the recognition that the use of aluminum nitride materials for film layers, particularly those with an aluminum-to-nitrogen ratio in the range of 1.05 to 1.40, exhibits excellent properties in terms of both optical refractive properties and the mechanical stability of film layers manufactured from such materials, especially in the advantageous range of 1.10 to 1.30. Furthermore, the desired mechanical tensile stress can be set reproducibly. To obtain a flat, self-supporting AlN film, the layer stress of the film can be set to a tensile stress of, for example, 100 MPa to 1000 MPa. The aluminum-to-nitrogen ratio can be assumed as the atomic ratio of aluminum atoms to nitrogen atoms, which can also be called the molar ratio. The ratios presented herein significantly improve the flexibility of device design, allowing the device design to be adapted to a wide range of optical applications, and because the film layer has high mechanical stability, it can also be used in robust applications. Furthermore, the failure rate due to mechanical damage of devices manufactured by the approach presented herein is reduced, significantly improving the handling of the support substrate or semiconductor material during processing.

[0016] The solutions presented herein lead to improvements in the mechanical and optical properties, manufacturability, and long-term stability of the elements. Furthermore, especially in the case of self-supporting films, the lifespan of the film layer can be extended by preventing or delaying degradation due to a decrease in the tensile stress of the film, compared to known film layers consisting of stoichiometric AlN films.

[0017] In this specification, a protective coating can be understood as a covering of a film layer. In this case, the protective coating and passivation coating are preferably composed of or contain a material whose structure and / or composition is not altered by water, or which is not altered by water, and which ensures that the film layer is fluidly sealed from around the semiconductor element (e.g., up to the side edge of the wafer). This method ensures that the film layer is not damaged and the semiconductor element is not destroyed during processing or patterning of the support substrate or the area of ​​the semiconductor element. A wet chemical method can be understood as one or more process steps of a wet etching method or a wet cleaning method, in which a liquid etching agent and / or cleaning agent is used to form a pattern on the semiconductor material or to clean the surface of the semiconductor material. A dry etching method can be understood as a process step in which a semiconductor material is patterned by the use of a physical or mechanical removal process or by the use of a gaseous etching agent. Furthermore, the first and second dry etching steps can be performed by the same dry etching method and / or in a single process step, but this is not necessarily required. It is also advantageous to perform the two dry etching steps consecutively from one side of the semiconductor device. Moreover, while it is advantageous to perform the preparation, removal, and exposure steps in the order described above, the first and second dry etching steps can be performed as part of the exposure step, and they can also be performed in any order.

[0018] The approach proposed herein offers the advantage of ensuring that film layers sensitive to etching or cleaning agents used in any of the process steps are not damaged as much as possible by using different etching or cleaning methods at different process stages.

[0019] Advantageously, one embodiment of the approach proposed herein has additional steps. f) A step of applying a cover layer on a protective coating, wherein the protective coating, together with the cover layer, forms a laminate as a protective layer, and the material of the protective coating is different from the material of the cover layer.

[0020] It is advantageous to apply the cover layer after applying the protective coating in step c) and before exposure in step e), and especially before removing a portion of the support substrate in step d).

[0021] In particular, the material of the cover layer may be a reflective material and / or a metal.

[0022] This method may further include steps performed before the second dry etching step, and in particular before the step of removing a portion of the support substrate (step d). g) A step of patterning a protective layer, wherein the protective film is at least partially exposed by removing the cover layer, particularly under the use of an auxiliary mask, using an etching method used in a first or second dry etching method, or another etching method.

[0023] Such embodiments have the advantage of allowing highly flexible patterning of the protective layer by using different materials for multiple coatings of the protective layer, thereby enabling flexible morphologies of the exposed film layer in subsequent process steps. By using a metal for the cover layer, electrical conduction lines can be formed on the surface of the element. By using a reflective material for the cover layer, for example, desired optical properties can be achieved on the finished element, and / or reflective markings can be applied for positioning semiconductor elements or for positioning wafers on which multiple semiconductor elements are arranged.

[0024] To form a self-supporting film, in the patterning step, a part of the support substrate can be removed within the patterned area, thereby forming an area without a substrate. Such an embodiment of the approach proposed herein offers the possibility of preparing a semiconductor material or a semiconductor device using known efficient processing steps so that only a dry etching method can be used in subsequent exposure steps. Thus, by pre-processing the semiconductor material, when the surface of the film layer is already exposed, it can be prevented that the surface is damaged by an etching agent or a cleaning agent that is overly aggressive with respect to the material of the film layer.

[0025] Particularly advantageously, in one embodiment of the approach proposed herein, the patterning step is performed such that the film layer is sealed against wet chemical etching agents or cleaning agents by a passivation coating and at least a part of a protective coating. Such an embodiment has the advantage of reliably protecting the film layer from wet chemical etching agents, thereby preventing damage to the film layer.

[0026] According to a further embodiment of the approach proposed herein, in the exposure step, the passivation coating and at least a part of the protective coating can be removed by a dry etching method. Such an embodiment of the approach proposed herein has the advantage that a dry etching method is already applied when the film layer is first exposed, thereby protecting the film layer as well as possible or patterning it efficiently.

[0027] Particularly finely detailed and application-efficiently formed semiconductor devices can be manufactured when the film layer itself is not only exposed but also patterned. For this purpose, for example, through holes can be provided in the exposed portion of the film layer to realize an electromagnetic radiation attenuator or an optical structure, such as an aperture structure. Such an aperture structure may have through holes with a diameter larger than the design wavelength of the device in order to form a conventional aperture. Therefore, according to one particularly preferred embodiment, in the exposure step, the film layer can be at least partially removed to obtain a perforated exposed film portion. In particular, in this case, the patterned area of ​​the protective coating and / or a resist mask applied on the protective coating and / or cover layer can be used as an etching mask. Such perforations may have holes with a diameter larger than the design wavelength of the device in order to form a conventional aperture. Alternatively, holes with a diameter smaller than the design wavelength of the device may be provided to generate attenuated electromagnetic waves or to function as a short-pass filter. The perforated film portion can serve as a diffraction grating for electromagnetic radiation. In this invention, electromagnetic radiation can be interpreted as X-rays, XUV radiation, UV radiation, visible light, and infrared radiation. The optical function of this element (at the design wavelength) can be provided in each of the above wavelength regions. The tensile stress of the film can prevent undesirable warping of the film.

[0028] Furthermore, such elements can be used as ultrasonic detectors. In this case, the displacement of the membrane can be evaluated, for example, capacitively or optically. For this application, the permanently maintained tensile stress of the membrane may be of particular importance.

[0029] Furthermore, such elements with through-holes in the membrane can be used as effective pressure reducers for gases. The size of the openings can be selected to be small enough to allow Knudsen flow or molecular flow. This allows, for example, the reproducible injection of trace amounts of gas into the gas flow. Such pressure reducers can also be used as test leaks for testing high vacuum equipment.

[0030] Furthermore, according to another embodiment of the approach presented herein, in the patterning step and the exposure step, the film layer, support substrate, protective coating, masking coating, and passivation coating are removed in through-regions laterally adjacent to the patterned region such that no part of the film layer protrudes, forming an opening. Such an embodiment of the approach proposed herein has the advantage that, by the method presented herein, other regions of the semiconductor material where exposed film layers are not required can also be patterned. This method allows for compact patterning of semiconductor materials or semiconductor devices with fewer work steps, thereby reducing manufacturing costs and manufacturing time.

[0031] Furthermore, in one embodiment, it is particularly preferable that in the patterning step, a retaining material is provided to a portion of the passivation film exposed in the through-region, and that in the exposure step after removing the support substrate and the passivation film in the through-region, the retaining material is removed to form an opening. The retaining material can be understood as, for example, a plastic material that can also be used to introduce patterns into different films of a semiconductor material, such as a photoresist. Alternatively, the retaining material may be provided on the surface of a semiconductor material or semiconductor device together with another material. For example, by using such a semiconductor material provided directly to the passivation film, it is possible to prevent flakes or fragments of the film to be removed from falling uncontrollably into the processing space and causing errors in subsequent steps. Rather, such fragments that may be generated by continuously reducing the thickness of the layer to be removed are supported or materially bound by the retaining material, thereby making it possible to completely remove or detach these fragments. In this case, it is advantageous to apply the retaining material to the surface of the passivation film opposite to the substrate in a given through-region.

[0032] In one embodiment of the approach proposed herein, the exposure step can be very flexibly performed to form an opening having a larger diameter than the opening in the film layer of the exposed area. Such embodiments have the advantage that patterns of different dimensions can be introduced into the semiconductor material by a unified method or process, thereby enabling the efficient realization of desired functions in the device.

[0033] Semiconductor devices with particularly advantageous properties can be realized when the following semiconductor materials are prepared in the preparation step: the passivation film and / or masking film comprises at least partially silicon nitride, and / or the film layer comprises at least partially aluminum nitride, germanium oxide, and / or aluminum oxide, and / or the cover layer comprises a metal, particularly chromium, and / or the protective film comprises silicon and / or silicon nitride. This method makes it possible to realize semiconductor devices with designs that are particularly advantageous for optical applications.

[0034] Particularly advantageous, embodiments are available in which, in order to implement various steps of the approach presented herein, the patterning step includes a wet etching method using potassium hydroxide or tetramethylammonium hydroxide as the etching agent, and / or a wet chemical cleaning method, and / or in the exposure step, a dry etching method using a physical dry etching method, a chemical dry etching method, and / or a physicochemical dry etching method is performed.

[0035] In this case, the thickness of the film layer can be between 5 nm and 1000 nm, preferably between 10 nm and 500 nm, particularly preferably between 20 nm and 200 nm, and most preferably between 40 nm and 150 nm. One such embodiment has the advantage that, due to its thin thickness, it can achieve very favorable electromagnetic properties for the film layer or the device having the film layer compared to the prior art. For example, the refractive index of the self-supporting film in the short wavelength range is close to 1, and the absorption coefficient is greater than 0.03. At the same time, this thickness allows for a sufficiently stable film layer when the above stoichiometric ratio is selected (and due to the generation of stress). For this purpose, it is advantageous to set the thickness of the film layer to at least 10 nm, preferably at least 20 nm, and more preferably at least 40 nm. This method greatly expands the usability of the device thus manufactured, because it allows for the design of the device to be expanded to a wide variety of technological fields or to use in various wavelength ranges.

[0036] One embodiment of the approach proposed herein is particularly advantageous when, in the step of applying the film layer, a plasma process is performed, in particular for cleaning the provided film layer, and in particular when the plasma process uses hydrogen and / or oxygen plasma. Such an embodiment has the advantage that the plasma process can obtain a cleaned film layer that has high-quality optical properties while simultaneously retaining mechanical stress that has a very favorable effect on the stability of such an element.

[0037] Furthermore, in one embodiment of the approach proposed herein, it is preferable to supply nitrogen into the process space in which the film layer is provided on the passivation film during the step of applying the film layer. In particular, the amount of nitrogen supplied into the process space is less than the amount of nitrogen required for the production of a stoichiometric film layer. Such an embodiment has the advantage that the ratio of aluminum to nitrogen during the deposition or formation of the film layer can be adjusted with great precision by controlling the supply of nitrogen, thereby enabling a high degree of flexibility in achieving a desired combination of material parameters in the production of the film layer.

[0038] Advantageously, the lateral extent of the film's exposed region is preferably between 50 μm and 5000 μm, particularly between 100 μm and 500 μm.

[0039] The film may be perforated, for example, by a hole pattern with lateral hole spacings between 50 nm and 5000 nm, preferably between 100 nm and 1000 nm. The film can be used, for example, for absorption and / or diffraction of electromagnetic radiation.

[0040] Furthermore, one embodiment of the approach presented herein is advantageous when the non-substrate region of the semiconductor material has an edge, the normal of the edge having an angle of less than 60°, particularly less than 54.7°, with respect to the surface normal of the supporting substrate, and the semiconductor material is a single crystal and the edge is formed by an etching-resistant crystal plane. For example, a silicon wafer having a {100} surface can be used. If the edge is formed by {111} and equivalent crystal planes, the angle is 54.74°.

[0041] These variations of the method can be implemented, for example, in software, in hardware, or in a hybrid form of software and hardware, such as control instructions within a control device or apparatus.

[0042] The approach presented herein further creates an apparatus formed to perform, control, or implement the steps of the modified method presented herein in a corresponding facility. Even with this modified apparatus of the present invention, the underlying problem of the present invention can be solved quickly and efficiently.

[0043] For this purpose, the device comprises at least one arithmetic unit for processing signals or data, at least one storage unit for storing signals or data, at least one interface to a sensor or actuator for reading sensor signals from a sensor or outputting data signals or control signals to an actuator, and / or at least one communication interface for reading or outputting data incorporated into a communication protocol. The arithmetic unit may be, for example, a signal processor, a microcontroller, and the storage unit may be flash memory, EEPROM, or a magnetic storage unit. The communication interface may be configured to read or output data wirelessly and / or wired, and a communication interface capable of reading or outputting data wired may read this data electrically or optically from, for example, a corresponding data transmission line, or output it to a corresponding data transmission line.

[0044] In this specification, "device" can be understood as an electrical device that processes sensor signals and, depending on them, outputs control signals and / or data signals. The device may have an interface that can be formed from hardware and / or software. If formed from hardware, the interface may be, for example, part of a so-called system ASIC that includes various functions of the device. However, the interface may also be a proprietary integrated circuit, or at least partly composed of discrete components. If formed from software, the interface may be, for example, a software module that exists on a microcontroller along with other software modules.

[0045] Furthermore, computer program products or computer programs including program code are also advantageous. The program code can be stored in a machine-readable carrier or storage medium such as semiconductor memory, hard disk memory, or optical memory, and is used for the execution, conversion, and / or control of the steps of the method according to any of the embodiments described above. It is particularly advantageous if the program product or program is executed on a computer or device.

[0046] A further aspect of the present invention is a support substrate for manufacturing at least one element, comprising at least one exposed film portion and a passivation film disposed on a first surface, wherein a film layer is disposed on the passivation film, the film layer being formed from an aluminum nitride material having an aluminum-to-nitrogen ratio in the range of 1.05 to 1.4, the side of the film layer opposite the passivation film being covered by a protective film, the protective film comprising silicon and / or silicon nitride, the protective film together with a cover layer forming a laminate as a protective layer, the material of the protective film being different from the material of the cover layer, the cover layer comprising a metal, and furthermore, an etching mask for wet etching of the substrate is provided on a second surface of the support substrate opposite to the first surface. This support substrate can also be advantageously used in the manufacture of elements.

[0047] Examples of the approach presented herein are shown in the drawings and described in detail below. [Brief explanation of the drawing]

[0048] [Figure 1A] This shows a cross-sectional view of a semiconductor device manufactured according to the first embodiment, at one process step. [Figure 1B] This shows a cross-sectional view of a semiconductor device manufactured according to the first embodiment, at one process step. [Figure 1C] This shows a cross-sectional view of a semiconductor device manufactured according to the first embodiment, at one process step. [Figure 1D] This shows a cross-sectional view of a semiconductor device manufactured according to the first embodiment, at one process step. [Figure 1E] This shows a cross-sectional view of a semiconductor device manufactured according to the first embodiment, at one process step. [Figure 2A] This shows a cross-sectional view of a semiconductor device manufactured according to the second embodiment, at one process step. [Figure 2B] This shows a cross-sectional view of a semiconductor device manufactured according to the second embodiment, at one process step. [Figure 2C] This shows a cross-sectional view of a semiconductor device manufactured according to the second embodiment, at one process step. [Figure 2D] This shows a cross-sectional view of a semiconductor device manufactured according to the second embodiment, at one process step. [Figure 2E] This shows a cross-section of a semiconductor device manufactured according to the second embodiment at one process step. [Figure 2F] This shows a cross-section of a semiconductor device manufactured according to the second embodiment at one process step. [Figure 2G] This shows a cross-sectional view of a semiconductor device manufactured according to the second embodiment, at one process step. [Figure 2H]This shows a cross-sectional view of a semiconductor device manufactured according to the second embodiment, at one process step. [Figure 2I] This shows a cross-sectional view of a semiconductor device manufactured according to the second embodiment, at one process step. [Figure 3] The following are multiple sub-diagrams showing cross-sectional views of a semiconductor device manufactured according to the third embodiment at different process steps. [Figure 4] This shows a schematic cross-sectional view of a stacked structure used as a raw material for semiconductor devices. [Figure 5] This shows a cross-sectional view of a patterned wafer containing semiconductor elements. [Figure 6] A plan view of a patterned aluminum nitride film manufactured by the proposed process flow is shown. [Figure 7] A flowchart of one embodiment of a semiconductor device manufacturing method is shown. [Figure 8] A block diagram of one embodiment of a semiconductor device manufacturing apparatus is shown. [Modes for carrying out the invention]

[0049] In the following description of preferred embodiments of the present invention, elements shown in various figures and having similar functions will be referred to by the same or similar reference symbols, and repeated descriptions of these elements will be omitted.

[0050] Figure 1 consists of several sub-figures, designated as Figures 1A to 1E, each showing a cross-sectional view of a semiconductor device 100 manufactured according to the first embodiment after different process steps.

[0051] Figure 1A first shows a semiconductor material 102 in the form of multiple stacked layers. The semiconductor material 102 includes a support substrate 104, which is manufactured from, for example, silicon, or contains this material. The semiconductor substrate 104 further includes an underside masking film 106 and a passivation film 108, which, for example, each have, or contain, silicon nitride (Si3N4). The masking film 106 and the passivation film 108 can be formed on the support substrate 104 in, for example, the same manufacturing step. A film layer 110 made of aluminum nitride with an aluminum-to-nitrogen ratio in the range of 1.05 to 1.4 is placed on the passivation film 108. A protective film 114 is placed on the film layer 110. This protective film 114 can be made of, for example, silicon, silicon nitride, silicon oxide, and / or metal, or any of these materials. However, it may also be a resist film, such as a photoresist.

[0052] In this embodiment, in the first process step, the masking film 106 is patterned using, for example, a photoresist for exposure and / or a wet etching method, or alternatively, a dry etching method.

[0053] Figure 1B shows a cross-sectional view of the semiconductor device 100 after this process step has been performed.

[0054] According to a first embodiment of the manufacturing of the semiconductor device 100 shown in Figure 1, the following process step involves etching the support substrate 104 using a wet etching method. The wet etching method allows for the formation of inclined sides by appropriately adjusting the crystal structure of the support substrate 104 through openings in the masking film 106 on the support substrate. The formation of such sides is highly advantageous for optical applications, as will be detailed below. Etching is carried out until a passivation film 108, which functions as a stop film for the wet etching method, is exposed on its back surface. This method prevents water-soluble or water-sensitive film layers 110 from being eroded, damaged, or destroyed by the wet etching method. In variations not shown in this embodiment, the sides of the grooves can be etched perpendicular to the masking film, and / or the masking film can be under-etched.

[0055] Figure 1C shows a cross-sectional view of the semiconductor device 100 after this process step has been performed. At this point, a region 130 without substrate is created. In this region 130, the passivation film 108 is exposed on one side, the bottom surface in the figure. Simultaneously, this state of the semiconductor device 100 is the final state in this manufacturing embodiment that allows for processing by the wet etching method. Subsequent steps are performed under dry etching to avoid damage or destruction of the film layer 110 by water molecules.

[0056] In a further step, the first partial step removes the passivation film 108 from the substrate-free region 130, and the second partial step removes the protective film 114. These two partial steps can be performed in any order or simultaneously. Dry etching is used for this removal. Using a wet etching process step would erode and damage the film layer 110 at this stage; therefore, according to the approach presented in this embodiment, only dry etching should be used for processing the semiconductor device 100 from this stage onward. In the first embodiment shown, the passivation film is removed only in the substrate-free region 130 because etching is not possible in other areas where the substrate remains. In the illustrated embodiment, the protective film is partially removed only in the region containing the self-supporting film. For this purpose, the protective film can be selectively etched using an auxiliary mask (not shown).

[0057] Figure 1D shows a cross-sectional view of the semiconductor device 100 after this process step has been performed. The masking film 106 may remain on the device, as shown, but is not required. In the illustrated example, the protective film 114 is partially removed in a selected area slightly larger than the area without substrate 130. In an unillustrated variation, the protective film 114 is removed in the area corresponding to the area without substrate 130. In another unillustrated variation, the protective film 114 is removed in an area smaller than the area without substrate 130.

[0058] Figure 1E shows a cross-sectional view of the semiconductor device 100 in another modification of the first embodiment, where the protective coating has been completely removed. In a further modification of the first embodiment, in a subsequent step, the masking film 106 is further removed and, if necessary, the individual parts of the semiconductor device 100 are separated. Figure 2 shows several sub-views, shown as Figures 2A to 2I, each showing a cross-sectional view of the semiconductor device 100 after different process steps, manufactured according to the second embodiment.

[0059] Figure 2A first shows a semiconductor material 102 in which multiple layers are stacked. The semiconductor material 102 includes a support substrate 104, which is manufactured from or contains silicon, for example. The semiconductor substrate 104 further includes an underside masking film 106 and a passivation film 108, which each have, for example, silicon nitride (Si3N4) or contain this material. The masking film 106 and the passivation film 108 can be formed on the support substrate 104 by, for example, the same manufacturing step. A film layer 110 made of aluminum nitride with an aluminum-to-nitrogen ratio in the range of 1.05 to 1.4 is placed on the passivation film 108. A protective layer 112 is placed on the film layer 110, and this protective layer 112 includes, for example, a protective film 114 and a cover layer 116 placed on the protective film 114. The protective coating 114 has a silicon-based semiconductor material and can be formed as an etching stop coating. The cover layer 116 may be composed of, for example, a reflective material and / or a metal, such as chromium, or a material containing such a material.

[0060] In the initial processing step, for example, a cover layer 116, such as a reflective material, is patterned, and for this patterning, a photoresist is used that is exposed according to the pattern to be introduced into the cover layer 116. For patterning the cover layer 116, a wet etching method, or, as an alternative or addition, a dry etching method, can be used.

[0061] Figure 2B shows a cross-sectional view of the semiconductor device 100 after the above process steps have been performed.

[0062] Next, according to this embodiment, the masking film 106 is patterned. For example, this is also done using an exposure photoresist and / or by a wet etching method, or alternatively by a dry etching method.

[0063] Figure 2C shows a cross-sectional view of the semiconductor device 100 after this process step has been performed.

[0064] In a further process step, a photoresist is used as an etching mask 120 to pattern the semiconductor device 100, for example, to realize patterns of different lattice types. This allows for the patterning of a substrate lattice type 122 and, on the other hand, a film lattice 124 in a different region.

[0065] Figure 2D shows a cross-sectional view of the semiconductor device 100 after this process step has been performed.

[0066] According to the example of the semiconductor device 100 shown in Figure 2, in a further process step, the support substrate 104 is etched using a wet etching method. By using the wet etching method, it is possible to form inclined sides rather than grooves through openings in the masking film 106 within the support substrate, by appropriately adjusting the crystal structure of the support substrate 104. Forming such sides is very advantageous for optical applications, as will be described later. Etching is carried out until a passivation film 108, which functions as a stop layer for the wet etching method, is exposed on the back surface. This method prevents water-soluble or water-sensitive film layers 110 from being eroded, damaged, or destroyed by the wet etching method.

[0067] Figure 2E shows a cross-sectional view of the semiconductor device 100 after this process step has been performed. At the same time, this state of the semiconductor device 100 is the final state in this embodiment of manufacturing that is ready for processing by a wet etching step. Subsequent steps are performed using a dry etching method to avoid damage or destruction of the film layer 110, which is composed of or contains a water-soluble material.

[0068] In the subsequent step, the sacrificial film is removed. In this embodiment, the sacrificial film consists of the portion of the passivation film 108 exposed from the back surface of the support substrate 104, and the portion of the protective film 114 not covered by the etching mask 120 and / or the photoresist as a cover layer 116. For this removal, a dry etching method is used because the film layer 110 is exposed in the patterning region 130 and the through-region 132. If a wet etching step is used in this state, the film layer 110 will also be eroded and damaged. Therefore, according to the approach presented in this embodiment, from this stage onward, only dry etching must be used for processing the semiconductor device 100.

[0069] Figure 2F shows a cross-sectional view of the semiconductor device 100 after this process step has been executed.

[0070] Subsequently, in a further process step, for example, the film layer 110 in the through-region 132 can be removed, thereby forming a wide opening 136 in the semiconductor element 100. Furthermore, in the patterning region 130, the exposed film layer 110 can be removed by the patterned protective layer 112, particularly by the patterned protective coating 114 and the patterned cover layer 116, which can be achieved, for example, by a dry etching method applied from above. This method allows the film layer 110 containing water-soluble or water-sensitive materials to be patterned as needed. At the same time, very fine patterns, such as holes 138, can be realized in the patterning region 130 of the film layer 110, which makes it possible, for example, to form the later-manufactured exposed film layer 110 as a movable element.

[0071] Figure 2G shows a cross-sectional view of the semiconductor device 100 after this process step has been performed.

[0072] Furthermore, in the next step, the areas of the protective layer 112 not covered by the etching mask 120, that is, the uncovered portions of the protective film 114 and the cover layer 116, are etched or removed, thereby forming exposed film portions 140 of the film layer 110. These film portions 140 also include fine patterns, such as through holes 138. In this case, the diameter of these through holes 138 can be made considerably smaller than the openings 236 of the through-hole region 132.

[0073] Figure 2H shows a cross-sectional view of the semiconductor device 100 after this process step has been performed.

[0074] Finally, in a subsequent step, the etching mask 120 is removed or (dry) etched to separate the individual elements of the semiconductor device 100, if necessary.

[0075] Figure 2I shows a cross-sectional view of the semiconductor device 100 after this process step has been performed.

[0076] Therefore, a partial diagram of Figure 2 illustrates an example of a process flow for producing a self-supporting, patterned, non-stoichiometric aluminum nitride film under the use of a sacrificial protective coating and standard CMOS process steps. In all critical steps, sensitive layers such as film layer 110 are protected, thereby enabling the use of wet, and thus cost-effective, process steps.

[0077] The approach presented in this embodiment allows for the production of an ultrathin, self-supporting, and patterned film layer 110 from a coating material sensitive to wet processes. This method efficiently enables the production of self-supporting ultrathin films, which typically require numerous wet chemical process steps, such as lithography and wafer cleaning. For the production of self-supporting films, the entire wafer is usually etched by either dry etching or wet etching. In dry etching methods such as DRIE (deep reactive ion etching), an etching profile nearly perpendicular to the wafer is formed, while in wet etching methods, an inclined etching profile may be formed in the etched grooves. In optical applications, inclined V-shaped sidewalls produced by wet etching are preferred to allow high NA (numerical aperture) electromagnetic radiation to pass through the film without being obstructed by the sidewalls of the wafer holes. When the film is used in hydrodynamic applications, the inclined sidewalls can act as a nozzle or diffuser. However, when the film is formed from aluminum nitride, the use of known wet etching methods is difficult or impossible. On the other hand, the approach presented in this embodiment introduces a process flow that enables the manufacture of almost all self-supporting film materials. Furthermore, a method for manufacturing patterned films is also described.

[0078] The fabrication of self-supporting films is a widely used technique, for example, for MEMS products or optical sensors. Typically, robust materials such as SiN or metals are used as the film material or the material for the film layer 110. However, depending on the application, the use of aluminum nitride is also desirable. This material, at least in thin films, can be hydrolyzed by water, making direct wet process steps impossible. Furthermore, cleaning processes using commonly used water-based cleaning chemicals are also impossible. The method presented in this embodiment allows for the inexpensive wet chemical fabrication of desired components, and may even have inclined substrate etching edges. The fundamental idea of ​​the present invention is various sacrificial layers that protect the sensitive layer of the film layer 110 from the wet environment. This approach makes it possible to pattern films from non-stoichiometric aluminum nitride and, furthermore, to partially impart reflective material suitable for optical or ultrasonic sensor applications. Regarding patterning accuracy, there are no limitations other than the resolution limits of the lithography and etching tools used. In this embodiment, a minimum patterning size of less than 200 nm is shown, which is within the resolution limits of the tools.

[0079] The proposed process is described based on the semiconductor device manufacturing steps shown in the partial diagram of Figure 2. This process includes various standard process steps, such as coating, lithography, cleaning, and wet and dry etching. The use of the proposed process route allows for more wet cleaning steps to be performed, thereby improving the overall quality of surface defects. In particular, it makes it possible to utilize, at least partially, the crucial wet etching step for device manufacturing.

[0080] A key aspect of the proposal presented in this embodiment is the use of protective coatings beneath and above the moisture-sensitive layer (silicon nitride) during all wet process steps. These protective coatings are ultimately removed by etching. The lamination is chosen to allow selective etching of individual layers without etching other masking and / or protective coatings. A further advantage of the proposed approach, or lamination, is that the optical reflectivity can be adjusted by the selected materials and / or layer thicknesses. For example, the introduction of protective coatings makes it possible to reduce the reflectivity to near zero, for example, in the case of green light, or to achieve maximum reflectivity simply by changing the layer thickness.

[0081] In the proposed process flow, the steps between processing stages shown in Figures 1F and 1G present a challenge. When etching the final freestanding layer, if a large hole is created, such as in the area of ​​the through-hole 136, this layer gradually thins. If the remaining layer is too thin (a few nanometers) to remain intact, the film, or in this embodiment, the film layer 110, breaks and curls into a foil (flitter) before the etching process is complete. These fragments may consist of moisture-sensitive materials and act as an undesirable masking film in subsequent processes. For this reason, a further optimized process flow was developed to avoid these foils that may be generated by large openings.

[0082] Figure 3 shows cross-sectional views of a semiconductor device 100 manufactured according to a third embodiment at different process steps, in multiple sub-views. Starting from the processed state of the semiconductor device 100 shown in Figure 2C, in the first intermediate step shown on the right, a shading mask 200 is first used, which is then used by dry etching in the dry etching step to remove the protective film 114 from the through-region 132. This method exposes the film layer 110 in the through-region 132. In the next process step, the exposed film layer 110 is removed by wet etching or dry etching. Then, the procedure shown in Figure 2D is returned, but this time an etching mask 120 is also provided over the exposed upper passivation film 108. In subsequent steps, particularly during the transition between processing states of the semiconductor device 100 shown in Figures 2F and 2G, it is ensured that the upper passivation film 108 (not the film layer 110 of the through-region 132, which has already been removed) does not collapse into a foil that could potentially act as a defective optical mask.

[0083] Therefore, Figure 3 shows an optimized diagram to prevent foil generation from the film layer material. Two new process steps are included to selectively etch the layer in the region of the large film opening 136, i.e., the through-region 132. All other process steps are identical or very similar to the process flow described above in Figure 2.

[0084] Two additional process steps (shown on the right side of Figure 3) are for selectively removing the moisture-sensitive, non-stoichiometric aluminum nitride layer (film layer) 110 located at the large opening. Various etching methods can be used. In this process diagram, a shadow mask is used, for example, to open the buffer layer. All other processes basically correspond to the procedure described above in Figure 2, for example. The only difference is that in the step leading to the semiconductor device shown in Figure 2D, a slightly modified photomask is used as the etching mask 120 to keep the large opening closed with photoresist. This improved process flow makes it possible to replace the critical step of etching with a moisture-sensitive self-supporting layer with a process step of etching against a thick (self-supporting) photoresist 120. This makes it possible to avoid, for example, the generation of foil or flakes consisting of torn ultrathin material during the process.

[0085] Figure 4 is a schematic cross-sectional view showing an embodiment of a support substrate (104) for manufacturing at least one element (100) having at least one exposed film portion. A passivation film (108) is disposed on the first surface of the support substrate (104). A film layer (110) is disposed on the passivation film (108), and this film layer (110) is formed of an aluminum nitride material having an aluminum-to-nitrogen ratio in the range of 1.05 to 1.4. The surface of the film layer (110) opposite to the passivation film (108) is covered with a protective film (114). The protective film (114) contains silicon and / or silicon nitride. The protective film (114), together with a cover layer (116), forms a laminate as a protective layer (112), in which the material of the protective film (114) is different from the material of the cover layer (116). The cover layer (116) contains metal. An etching mask (106) for wet etching the substrate is provided on the second surface of the support substrate, opposite to the first surface.

[0086] In an advantageous particular form of the above embodiment, the masking film 106 and the passivation film 108 can be configured, for example, as etching stop films. For example, they can each include a silicon nitride film with a thickness of 100 nm. In a further advantageous special form of the above embodiment, the film layer 110 can have a thickness of, for example, 50 nm to 150 nm. In a further advantageous special form of the above embodiment, the protective film 114 can have a thickness of, for example, 20 nm to 200 nm. In a further advantageous special form of the above embodiment, the protective film 114 can be formed as stoichiometric silicon nitride Si3N4 or as any non-stoichiometric SixNy, preferably in a silicon excess state. In a further advantageous special form of the above embodiment, the cover layer 116 can be formed, for example, as a chromium metal layer, with a thickness of, for example, 20 nm to 200 nm.

[0087] Figure 5 shows a cross-section of a patterned wafer having a semiconductor element 100, the wafer having reflective markings within a metal coating 116, a large opening 136 that allows access to the back surface of the wafer, and small through-holes 138 as perforations of a freestanding, non-stoichiometric aluminum nitride film 140.

[0088] In this process, the lateral dimensions of the markings patterned on the metal film 116 and the holes 138 patterned on the freestanding portion 140 of the aluminum nitride film 110 are limited only by the resolution limits of the combination of lithography and dry etching tools. Patterning with lateral dimensions of approximately 100 nm can be achieved.

[0089] Figure 6 shows a typical top view observed in a REM (scanning electron microscope) image of a patterned, freestanding AlN film 110, which was manufactured by the proposed process flow. The circles represent holes 136 in the through-region 132 of the non-stoichiometric aluminum nitride film, which form free passages through the film 110 and the wafer 104. Furthermore, there is a substrate-free region 130 where through-holes 138 are drilled in the freestanding, non-stoichiometric aluminum nitride film 140.

[0090] Figure 7 shows a flowchart of a method 600 for manufacturing a semiconductor device having at least one exposed film portion. The method includes a step 610 of preparing a semiconductor material having a support substrate with a passivation film, wherein a film layer formed from an aluminum nitride material is placed on the passivation film, and in this material the ratio of aluminum to nitrogen is in the range of 1.05 to 1.4. The side of the film layer opposite to the passivation film is covered with a protective film. Furthermore, the method 600 includes a step 620 of removing a portion of the support substrate using a wet chemical method to obtain an exposed area of ​​the passivation film in a region of the semiconductor material that is not substrate-based. Finally, the method 600 includes a step 630 of exposing a portion of the film layer in a region that is not substrate-based by using a first dry etching step to etch the passivation film and a second dry etching step to etch the protective film.

[0091] Figure 8 shows a block diagram of apparatus 700 for manufacturing semiconductor devices. Apparatus 700 includes a unit 710 for preparing a semiconductor material having a support substrate with a passivation film. A film layer is placed on this passivation film, and the film layer is formed from an aluminum nitride material with an aluminum-to-nitrogen ratio in the range of 1.05 to 1.4, and the side of the film layer opposite the passivation film is covered with a protective layer. Furthermore, apparatus 700 includes a unit 720 for removing a portion 620 of the support substrate 104 using a wet etching method to obtain a substrate-free region of the semiconductor material. Finally, apparatus 700 includes a unit 730 for exposing a section of the film layer in the substrate-free region using a dry etching method to obtain an exposed film portion.

Claims

1. A method (600) for manufacturing a semiconductor element (100) having at least one exposed film portion, wherein the method (600) comprises the following steps: a) A step (610) of preparing a semiconductor material (102) having a support substrate (104) equipped with a passivation film (108), b) A step of applying a film layer (110) onto the passivation coating (108), wherein the film layer (110) is formed from an aluminum nitride material having an aluminum-to-nitrogen ratio in the range of 1.05 to 1.

4. c) A step of applying a protective coating (114) onto the film layer (110), wherein the surface of the film layer (110) opposite to the passivation coating (108) is covered by the protective coating (114), d) A step (620) to remove a portion of the support substrate (104) using a wet chemical method in order to obtain a substrate-free region (130) of the passivation film (108), e) A method (600) comprising: a first dry etching step for etching the passivation film and a second dry etching step for etching the protective film to expose a portion of the film layer (110) in a region without a substrate (130) in order to obtain an exposed film portion (140).

2. The method according to claim 1 (600), wherein the film layer has a thickness between 10 nm and 500 nm.

3. Furthermore, before step e, especially before step d, and after step c, f) A step of applying a cover layer (116) onto the protective coating (114), wherein the protective coating (114) together with the cover layer (116) forms a laminate as a protective layer (112), and the material of the protective coating (114) is different from the material of the cover layer (116), and in particular the material of the cover layer (116) has a reflective material and / or a metal, Furthermore, the following steps are performed prior to the second dry etching step, in particular prior to the step (620) of removing a portion of the support substrate: g) The method according to claim 1 or 2 (600), comprising the step of patterning the protective layer (112), wherein the protective coating (114) is at least partially exposed by removing the cover layer (116), particularly under the use of an auxiliary mask, using an etching method used in the first or second dry etching method, or another etching method.

4. In the patterning step and the exposure step (630), in the through-region (132) that is laterally adjacent to the region without substrate (130), The method according to claim 3 (600), characterized in that the film layer (110), the support substrate (104), the protective coating (114), and the passivation coating (108) are removed such that an opening (136) is formed through the semiconductor element (100), and in particular, no portion of the film layer (110) protrudes into the opening (136).

5. In the patterning step, in order to avoid contamination due to the peeling off of material residue of the passivation coating to be removed, a retaining material (210) is provided to the portion of the passivation coating (108) that is exposed in the penetrating region (132), and at that time, The method according to claim 4 (600), characterized in that, after removing the support substrate (104) and the passivation coating (108) in the through-portion region (132), the retaining material (210) is removed in the exposure step (630) to form the opening (136).

6. The method according to claim 4 or 5 (600), characterized in that, in the exposure step (630), the opening (136) is formed to have a larger diameter than the opening (138) in the exposed region (140) of the film layer (110).

7. The method according to any one of claims 1 to 6 (600), characterized in that, in the patterning step, a wet etching method is carried out using potassium hydroxide or tetramethylammonium hydroxide as an etching agent as a wet chemical method, and / or, in the exposure step (630), a first and / or second dry etching step is carried out using a physical dry etching method, a chemical dry etching method, and / or a physicochemical dry etching method.

8. The method according to any one of claims 1 to 7 (600), characterized in that a plurality of semiconductor elements are manufactured simultaneously on the support substrate.

9. The method according to any one of claims 1 to 8 (600), characterized in that at least one cleaning step with a water-containing cleaning agent, particularly a wet chemical cleaning process, is provided before the step (630) of exposing a portion of the film layer (110).

10. The method according to any one of claims 1 to 9 (600), characterized in that, in the exposure step (630), the film layer (110) is at least partially removed in order to obtain a perforated exposed film portion (140), and in particular, the resist mask (120) applied on the protective coating (114) and / or the cover layer (116) is used as an etching mask.

11. The method according to any one of claims 1 to 10 (600), characterized in that in the preparation step (610), a semiconductor material (102) having at least partially silicon nitride for the passivation film (108), and / or, in the same step, the cover layer (116) comprises a metal, in particular aluminum, or a transition metal, in particular titanium, nickel, chromium, tantalum, tungsten, and platinum, and / or the protective film (114) comprises silicon, and / or silicon oxide, and / or silicon nitride.

12. The method according to any one of claims 1 to 11 (600), wherein the region (130) of the semiconductor material (102) without the substrate has an edge, and the normal of the edge has an angle of less than 60°, particularly less than 54.7°, with respect to the surface normal of the support substrate, and in particular, the semiconductor material is a single crystal, and the edge is formed by an etching-resistant crystal plane.

13. Apparatus (700), Apparatus (700) configured to perform and / or control the steps (610, 620, 630) of the method (600) according to any one of claims 1 to 11 in corresponding units (710, 720, 730).

14. It is a computer program, A computer program configured to execute and / or control the steps of the method (600) according to any one of claims 1 to 10 when the computer program is executed on a computer unit.

15. A support substrate (104) for manufacturing at least one element (100), It comprises at least one exposed film portion and a passivation film (108) disposed on the first surface, A film layer (110) is placed on the passivation coating (108), The aforementioned film layer (110) is formed from an aluminum nitride material having an aluminum-to-nitrogen ratio in the range of 1.05 to 1.

4. The surface of the film layer (110) opposite to the passivation coating (108) is covered by a protective coating (114). The protective coating (114) comprises silicon and / or silicon nitride. The protective coating (114), together with the cover layer (116), forms a laminate as a protective layer (112). The material of the protective coating (114) is different from the material of the cover layer (116), and the cover layer (116) contains metal. Furthermore, a support substrate (104) is provided with an etching mask (106) for wet etching of the support substrate on a second surface opposite to the first surface of the support substrate.

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